From: Qing Zhang <[email protected]>
Use perf framework to manage hardware instruction and data breakpoints.
LoongArch defines hardware watchpoint functions for instruction fetch
and load/store operations, after the software configures hardware watchpoints
for instruction fetch and load/store operations. The processor hardware will
monitor the access address of the instruction fetch and load/store operation,
and will trigger the exception of the watchpoint when it meets the conditions
set by the watchpoint.
The hardware monitoring points for instruction fetching and load/store operations
each have a register for the overall configuration of all monitoring points,
a register for recording the status of all monitoring points, and four registers
required for configuration of each watchpoint individually.
Watchpoint related control status register chapters:
https://github.com/loongson/LoongArch-Documentation/releases/download/2022.08.12/
LoongArch-Vol1-v1.02-CN.pdf
Initial version has the following limitations:
- userspace debug is not yet enabled: work on ptrace/gdb is in progress
- no support for virtualization
Despite missing userspace debug, initial implementation can be tested: e.g.
see samples/hw_breakpoint and register_wide_hw_breakpoint.
TODO:
- Add Kernel tools that use hardware breakpoints: Kgdb, Ptrace
- Add hardware breakpoints/watchpoints for gdb
Signed-off-by: Qing Zhang <[email protected]>
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 12571eedc488..69199812fe74 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -99,6 +99,7 @@ config LOONGARCH
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER
select HAVE_GENERIC_VDSO
+ select HAVE_HW_BREAKPOINT if PERF_EVENTS
select HAVE_IOREMAP_PROT
select HAVE_IRQ_EXIT_ON_IRQ_STACK
select HAVE_IRQ_TIME_ACCOUNTING
diff --git a/arch/loongarch/include/asm/hw_breakpoint.h b/arch/loongarch/include/asm/hw_breakpoint.h
new file mode 100644
index 000000000000..a57caf117960
--- /dev/null
+++ b/arch/loongarch/include/asm/hw_breakpoint.h
@@ -0,0 +1,140 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+#ifndef __ASM_HW_BREAKPOINT_H
+#define __ASM_HW_BREAKPOINT_H
+
+#include <asm/loongarch.h>
+
+#ifdef __KERNEL__
+
+/* Breakpoint */
+#define LOONGARCH_BREAKPOINT_EXECUTE (0 << 0)
+
+/* Watchpoints */
+#define LOONGARCH_BREAKPOINT_LOAD (1 << 0)
+#define LOONGARCH_BREAKPOINT_STORE (1 << 1)
+
+struct arch_hw_breakpoint_ctrl {
+ u32 __reserved : 28,
+ type : 2,
+ len : 2;
+};
+
+struct arch_hw_breakpoint {
+ u64 address;
+ u64 mask;
+ struct arch_hw_breakpoint_ctrl ctrl;
+};
+
+/* Lengths */
+#define LOONGARCH_BREAKPOINT_LEN_1 0b11
+#define LOONGARCH_BREAKPOINT_LEN_2 0b10
+#define LOONGARCH_BREAKPOINT_LEN_4 0b01
+#define LOONGARCH_BREAKPOINT_LEN_8 0b00
+
+/*
+ * Limits.
+ * Changing these will require modifications to the register accessors.
+ */
+#define LOONGARCH_MAX_BRP 8
+#define LOONGARCH_MAX_WRP 8
+
+/* Virtual debug register bases. */
+#define CSR_CFG_ADDR 0
+#define CSR_CFG_MASK (CSR_CFG_ADDR + LOONGARCH_MAX_BRP)
+#define CSR_CFG_CTRL (CSR_CFG_MASK + LOONGARCH_MAX_BRP)
+#define CSR_CFG_ASID (CSR_CFG_CTRL + LOONGARCH_MAX_WRP)
+
+/* Debug register names. */
+#define LOONGARCH_CSR_NAME_ADDR ADDR
+#define LOONGARCH_CSR_NAME_MASK MASK
+#define LOONGARCH_CSR_NAME_CTRL CTRL
+#define LOONGARCH_CSR_NAME_ASID ASID
+
+/* Accessor macros for the debug registers. */
+#define LOONGARCH_CSR_READ(N, REG, T, VAL) \
+do { \
+ if (T == 0) \
+ VAL = csr_read64(LOONGARCH_CSR_##IB##N##REG); \
+ else \
+ VAL = csr_read64(LOONGARCH_CSR_##DB##N##REG); \
+} while (0)
+
+#define LOONGARCH_CSR_WRITE(N, REG, T, VAL) \
+do { \
+ if (T == 0) \
+ csr_write64(VAL, LOONGARCH_CSR_##IB##N##REG); \
+ else \
+ csr_write64(VAL, LOONGARCH_CSR_##DB##N##REG); \
+} while (0)
+
+static inline u32 encode_ctrl_reg(struct arch_hw_breakpoint_ctrl ctrl)
+{
+ u32 val = (ctrl.len << 2) | ctrl.type;
+
+ return val;
+}
+
+static inline void decode_ctrl_reg(u32 reg, struct arch_hw_breakpoint_ctrl *ctrl)
+{
+ ctrl->type = reg & 0x3;
+ reg >>= 2;
+ ctrl->len = reg & 0x3;
+}
+
+struct task_struct;
+struct notifier_block;
+struct perf_event_attr;
+struct perf_event;
+
+extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
+ int *gen_len, int *gen_type, int *offset);
+extern int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw);
+extern int hw_breakpoint_arch_parse(struct perf_event *bp,
+ const struct perf_event_attr *attr,
+ struct arch_hw_breakpoint *hw);
+extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
+ unsigned long val, void *data);
+
+extern int arch_install_hw_breakpoint(struct perf_event *bp);
+extern void arch_uninstall_hw_breakpoint(struct perf_event *bp);
+extern void hw_breakpoint_pmu_read(struct perf_event *bp);
+extern int hw_breakpoint_slots(int type);
+
+int breakpoint_handler(struct pt_regs *regs);
+int watchpoint_handler(struct pt_regs *regs);
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+extern void hw_breakpoint_thread_switch(struct task_struct *next);
+extern void ptrace_hw_copy_thread(struct task_struct *task);
+#else
+static inline void hw_breakpoint_thread_switch(struct task_struct *next)
+{
+}
+static inline void ptrace_hw_copy_thread(struct task_struct *task)
+{
+}
+#endif
+
+/* Determine number of BRP registers available. */
+static inline int get_num_brps(void)
+{
+ unsigned int ibcn;
+
+ ibcn = csr_read64(LOONGARCH_CSR_FWPC) & 0x3f;
+ return ibcn;
+}
+
+/* Determine number of WRP registers available. */
+static inline int get_num_wrps(void)
+{
+ unsigned int dbcn;
+
+ dbcn = csr_read64(LOONGARCH_CSR_MWPC) & 0x3f;
+ return dbcn;
+}
+
+#endif /* __KERNEL__ */
+#endif /* __ASM_BREAKPOINT_H */
diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
index 7f8d57a61c8b..e9aed583a064 100644
--- a/arch/loongarch/include/asm/loongarch.h
+++ b/arch/loongarch/include/asm/loongarch.h
@@ -970,42 +970,42 @@ static __always_inline void iocsr_write64(u64 val, u32 reg)
#define LOONGARCH_CSR_DB0ADDR 0x310 /* data breakpoint 0 address */
#define LOONGARCH_CSR_DB0MASK 0x311 /* data breakpoint 0 mask */
-#define LOONGARCH_CSR_DB0CTL 0x312 /* data breakpoint 0 control */
+#define LOONGARCH_CSR_DB0CTRL 0x312 /* data breakpoint 0 control */
#define LOONGARCH_CSR_DB0ASID 0x313 /* data breakpoint 0 asid */
#define LOONGARCH_CSR_DB1ADDR 0x318 /* data breakpoint 1 address */
#define LOONGARCH_CSR_DB1MASK 0x319 /* data breakpoint 1 mask */
-#define LOONGARCH_CSR_DB1CTL 0x31a /* data breakpoint 1 control */
+#define LOONGARCH_CSR_DB1CTRL 0x31a /* data breakpoint 1 control */
#define LOONGARCH_CSR_DB1ASID 0x31b /* data breakpoint 1 asid */
#define LOONGARCH_CSR_DB2ADDR 0x320 /* data breakpoint 2 address */
#define LOONGARCH_CSR_DB2MASK 0x321 /* data breakpoint 2 mask */
-#define LOONGARCH_CSR_DB2CTL 0x322 /* data breakpoint 2 control */
+#define LOONGARCH_CSR_DB2CTRL 0x322 /* data breakpoint 2 control */
#define LOONGARCH_CSR_DB2ASID 0x323 /* data breakpoint 2 asid */
#define LOONGARCH_CSR_DB3ADDR 0x328 /* data breakpoint 3 address */
#define LOONGARCH_CSR_DB3MASK 0x329 /* data breakpoint 3 mask */
-#define LOONGARCH_CSR_DB3CTL 0x32a /* data breakpoint 3 control */
+#define LOONGARCH_CSR_DB3CTRL 0x32a /* data breakpoint 3 control */
#define LOONGARCH_CSR_DB3ASID 0x32b /* data breakpoint 3 asid */
#define LOONGARCH_CSR_DB4ADDR 0x330 /* data breakpoint 4 address */
#define LOONGARCH_CSR_DB4MASK 0x331 /* data breakpoint 4 maks */
-#define LOONGARCH_CSR_DB4CTL 0x332 /* data breakpoint 4 control */
+#define LOONGARCH_CSR_DB4CTRL 0x332 /* data breakpoint 4 control */
#define LOONGARCH_CSR_DB4ASID 0x333 /* data breakpoint 4 asid */
#define LOONGARCH_CSR_DB5ADDR 0x338 /* data breakpoint 5 address */
#define LOONGARCH_CSR_DB5MASK 0x339 /* data breakpoint 5 mask */
-#define LOONGARCH_CSR_DB5CTL 0x33a /* data breakpoint 5 control */
+#define LOONGARCH_CSR_DB5CTRL 0x33a /* data breakpoint 5 control */
#define LOONGARCH_CSR_DB5ASID 0x33b /* data breakpoint 5 asid */
#define LOONGARCH_CSR_DB6ADDR 0x340 /* data breakpoint 6 address */
#define LOONGARCH_CSR_DB6MASK 0x341 /* data breakpoint 6 mask */
-#define LOONGARCH_CSR_DB6CTL 0x342 /* data breakpoint 6 control */
+#define LOONGARCH_CSR_DB6CTRL 0x342 /* data breakpoint 6 control */
#define LOONGARCH_CSR_DB6ASID 0x343 /* data breakpoint 6 asid */
#define LOONGARCH_CSR_DB7ADDR 0x348 /* data breakpoint 7 address */
#define LOONGARCH_CSR_DB7MASK 0x349 /* data breakpoint 7 mask */
-#define LOONGARCH_CSR_DB7CTL 0x34a /* data breakpoint 7 control */
+#define LOONGARCH_CSR_DB7CTRL 0x34a /* data breakpoint 7 control */
#define LOONGARCH_CSR_DB7ASID 0x34b /* data breakpoint 7 asid */
#define LOONGARCH_CSR_FWPC 0x380 /* instruction breakpoint config */
@@ -1013,42 +1013,42 @@ static __always_inline void iocsr_write64(u64 val, u32 reg)
#define LOONGARCH_CSR_IB0ADDR 0x390 /* inst breakpoint 0 address */
#define LOONGARCH_CSR_IB0MASK 0x391 /* inst breakpoint 0 mask */
-#define LOONGARCH_CSR_IB0CTL 0x392 /* inst breakpoint 0 control */
+#define LOONGARCH_CSR_IB0CTRL 0x392 /* inst breakpoint 0 control */
#define LOONGARCH_CSR_IB0ASID 0x393 /* inst breakpoint 0 asid */
#define LOONGARCH_CSR_IB1ADDR 0x398 /* inst breakpoint 1 address */
#define LOONGARCH_CSR_IB1MASK 0x399 /* inst breakpoint 1 mask */
-#define LOONGARCH_CSR_IB1CTL 0x39a /* inst breakpoint 1 control */
+#define LOONGARCH_CSR_IB1CTRL 0x39a /* inst breakpoint 1 control */
#define LOONGARCH_CSR_IB1ASID 0x39b /* inst breakpoint 1 asid */
#define LOONGARCH_CSR_IB2ADDR 0x3a0 /* inst breakpoint 2 address */
#define LOONGARCH_CSR_IB2MASK 0x3a1 /* inst breakpoint 2 mask */
-#define LOONGARCH_CSR_IB2CTL 0x3a2 /* inst breakpoint 2 control */
+#define LOONGARCH_CSR_IB2CTRL 0x3a2 /* inst breakpoint 2 control */
#define LOONGARCH_CSR_IB2ASID 0x3a3 /* inst breakpoint 2 asid */
#define LOONGARCH_CSR_IB3ADDR 0x3a8 /* inst breakpoint 3 address */
#define LOONGARCH_CSR_IB3MASK 0x3a9 /* breakpoint 3 mask */
-#define LOONGARCH_CSR_IB3CTL 0x3aa /* inst breakpoint 3 control */
+#define LOONGARCH_CSR_IB3CTRL 0x3aa /* inst breakpoint 3 control */
#define LOONGARCH_CSR_IB3ASID 0x3ab /* inst breakpoint 3 asid */
#define LOONGARCH_CSR_IB4ADDR 0x3b0 /* inst breakpoint 4 address */
#define LOONGARCH_CSR_IB4MASK 0x3b1 /* inst breakpoint 4 mask */
-#define LOONGARCH_CSR_IB4CTL 0x3b2 /* inst breakpoint 4 control */
+#define LOONGARCH_CSR_IB4CTRL 0x3b2 /* inst breakpoint 4 control */
#define LOONGARCH_CSR_IB4ASID 0x3b3 /* inst breakpoint 4 asid */
#define LOONGARCH_CSR_IB5ADDR 0x3b8 /* inst breakpoint 5 address */
#define LOONGARCH_CSR_IB5MASK 0x3b9 /* inst breakpoint 5 mask */
-#define LOONGARCH_CSR_IB5CTL 0x3ba /* inst breakpoint 5 control */
+#define LOONGARCH_CSR_IB5CTRL 0x3ba /* inst breakpoint 5 control */
#define LOONGARCH_CSR_IB5ASID 0x3bb /* inst breakpoint 5 asid */
#define LOONGARCH_CSR_IB6ADDR 0x3c0 /* inst breakpoint 6 address */
#define LOONGARCH_CSR_IB6MASK 0x3c1 /* inst breakpoint 6 mask */
-#define LOONGARCH_CSR_IB6CTL 0x3c2 /* inst breakpoint 6 control */
+#define LOONGARCH_CSR_IB6CTRL 0x3c2 /* inst breakpoint 6 control */
#define LOONGARCH_CSR_IB6ASID 0x3c3 /* inst breakpoint 6 asid */
#define LOONGARCH_CSR_IB7ADDR 0x3c8 /* inst breakpoint 7 address */
#define LOONGARCH_CSR_IB7MASK 0x3c9 /* inst breakpoint 7 mask */
-#define LOONGARCH_CSR_IB7CTL 0x3ca /* inst breakpoint 7 control */
+#define LOONGARCH_CSR_IB7CTRL 0x3ca /* inst breakpoint 7 control */
#define LOONGARCH_CSR_IB7ASID 0x3cb /* inst breakpoint 7 asid */
#define LOONGARCH_CSR_DEBUG 0x500 /* debug config */
diff --git a/arch/loongarch/include/asm/processor.h b/arch/loongarch/include/asm/processor.h
index 7184f1dc61f2..f6ee920122d6 100644
--- a/arch/loongarch/include/asm/processor.h
+++ b/arch/loongarch/include/asm/processor.h
@@ -11,6 +11,7 @@
#include <asm/cpu.h>
#include <asm/cpu-info.h>
+#include <asm/hw_breakpoint.h>
#include <asm/loongarch.h>
#include <asm/vdso/processor.h>
#include <uapi/asm/ptrace.h>
@@ -131,6 +132,9 @@ struct thread_struct {
* they are conditionally copied at fork().
*/
struct loongarch_fpu fpu FPU_ALIGN;
+ /* Hardware breakpoints pinned to this task. */
+ struct perf_event *hbp_break[LOONGARCH_MAX_BRP];
+ struct perf_event *hbp_watch[LOONGARCH_MAX_WRP];
};
#define thread_saved_ra(tsk) (tsk->thread.sched_ra)
@@ -172,6 +176,8 @@ struct thread_struct {
.fcc = 0, \
.fpr = {{{0,},},}, \
}, \
+ .hbp_break = {0}, \
+ .hbp_watch = {0}, \
}
struct task_struct;
@@ -184,10 +190,6 @@ extern unsigned long boot_option_idle_override;
*/
extern void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp);
-static inline void flush_thread(void)
-{
-}
-
unsigned long __get_wchan(struct task_struct *p);
#define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
diff --git a/arch/loongarch/include/asm/switch_to.h b/arch/loongarch/include/asm/switch_to.h
index 43a5ab162d38..24e3094bebab 100644
--- a/arch/loongarch/include/asm/switch_to.h
+++ b/arch/loongarch/include/asm/switch_to.h
@@ -34,6 +34,7 @@ extern asmlinkage struct task_struct *__switch_to(struct task_struct *prev,
#define switch_to(prev, next, last) \
do { \
lose_fpu_inatomic(1, prev); \
+ hw_breakpoint_thread_switch(next); \
(last) = __switch_to(prev, next, task_thread_info(next), \
__builtin_return_address(0), __builtin_frame_address(0)); \
} while (0)
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 7ca65195f7f8..b3aca7f2296e 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
+obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
obj-$(CONFIG_KPROBES) += kprobes.o kprobes_trampoline.o
diff --git a/arch/loongarch/kernel/hw_breakpoint.c b/arch/loongarch/kernel/hw_breakpoint.c
new file mode 100644
index 000000000000..16f38ceec321
--- /dev/null
+++ b/arch/loongarch/kernel/hw_breakpoint.c
@@ -0,0 +1,461 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+#define pr_fmt(fmt) "hw-breakpoint: " fmt
+
+#include <linux/hw_breakpoint.h>
+#include <linux/kprobes.h>
+#include <linux/perf_event.h>
+
+#include <asm/hw_breakpoint.h>
+
+/* Breakpoint currently in use for each BRP. */
+static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[LOONGARCH_MAX_BRP]);
+
+/* Watchpoint currently in use for each WRP. */
+static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[LOONGARCH_MAX_WRP]);
+
+/* Number of BRP/WRP registers on this CPU. */
+static int core_num_brps;
+static int core_num_wrps;
+
+int hw_breakpoint_slots(int type)
+{
+ /*
+ * We can be called early, so don't rely on
+ * our static variables being initialised.
+ */
+ switch (type) {
+ case TYPE_INST:
+ return get_num_brps();
+ case TYPE_DATA:
+ return get_num_wrps();
+ default:
+ pr_warn("unknown slot type: %d\n", type);
+ return 0;
+ }
+}
+
+#define READ_WB_REG_CASE(OFF, N, REG, T, VAL) \
+ case (OFF + N): \
+ LOONGARCH_CSR_READ(N, REG, T, VAL); \
+ break
+
+#define WRITE_WB_REG_CASE(OFF, N, REG, T, VAL) \
+ case (OFF + N): \
+ LOONGARCH_CSR_WRITE(N, REG, T, VAL); \
+ break
+
+#define GEN_READ_WB_REG_CASES(OFF, REG, T, VAL) \
+ READ_WB_REG_CASE(OFF, 0, REG, T, VAL); \
+ READ_WB_REG_CASE(OFF, 1, REG, T, VAL); \
+ READ_WB_REG_CASE(OFF, 2, REG, T, VAL); \
+ READ_WB_REG_CASE(OFF, 3, REG, T, VAL); \
+ READ_WB_REG_CASE(OFF, 4, REG, T, VAL); \
+ READ_WB_REG_CASE(OFF, 5, REG, T, VAL); \
+ READ_WB_REG_CASE(OFF, 6, REG, T, VAL); \
+ READ_WB_REG_CASE(OFF, 7, REG, T, VAL);
+
+#define GEN_WRITE_WB_REG_CASES(OFF, REG, T, VAL) \
+ WRITE_WB_REG_CASE(OFF, 0, REG, T, VAL); \
+ WRITE_WB_REG_CASE(OFF, 1, REG, T, VAL); \
+ WRITE_WB_REG_CASE(OFF, 2, REG, T, VAL); \
+ WRITE_WB_REG_CASE(OFF, 3, REG, T, VAL); \
+ WRITE_WB_REG_CASE(OFF, 4, REG, T, VAL); \
+ WRITE_WB_REG_CASE(OFF, 5, REG, T, VAL); \
+ WRITE_WB_REG_CASE(OFF, 6, REG, T, VAL); \
+ WRITE_WB_REG_CASE(OFF, 7, REG, T, VAL);
+
+static u64 read_wb_reg(int reg, int n, int t)
+{
+ u64 val = 0;
+
+ switch (reg + n) {
+ GEN_READ_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
+ GEN_READ_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
+ GEN_READ_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
+ GEN_READ_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
+ default:
+ pr_warn("attempt to read from unknown breakpoint register %d\n", n);
+ }
+
+ return val;
+}
+NOKPROBE_SYMBOL(read_wb_reg);
+
+static void write_wb_reg(int reg, int n, int t, u64 val)
+{
+ switch (reg + n) {
+ GEN_WRITE_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
+ GEN_WRITE_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
+ GEN_WRITE_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
+ GEN_WRITE_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
+ default:
+ pr_warn("attempt to write to unknown breakpoint register %d\n", n);
+ }
+}
+NOKPROBE_SYMBOL(write_wb_reg);
+
+enum hw_breakpoint_ops {
+ HW_BREAKPOINT_INSTALL,
+ HW_BREAKPOINT_UNINSTALL,
+};
+
+/**
+ * hw_breakpoint_slot_setup - Find and setup a perf slot according to
+ * operations
+ *
+ * @slots: pointer to array of slots
+ * @max_slots: max number of slots
+ * @bp: perf_event to setup
+ * @ops: operation to be carried out on the slot
+ *
+ * Return:
+ * slot index on success
+ * -ENOSPC if no slot is available/matches
+ * -EINVAL on wrong operations parameter
+ */
+static int hw_breakpoint_slot_setup(struct perf_event **slots, int max_slots,
+ struct perf_event *bp,
+ enum hw_breakpoint_ops ops)
+{
+ int i;
+ struct perf_event **slot;
+
+ for (i = 0; i < max_slots; ++i) {
+ slot = &slots[i];
+ switch (ops) {
+ case HW_BREAKPOINT_INSTALL:
+ if (!*slot) {
+ *slot = bp;
+ return i;
+ }
+ break;
+ case HW_BREAKPOINT_UNINSTALL:
+ if (*slot == bp) {
+ *slot = NULL;
+ return i;
+ }
+ break;
+ default:
+ pr_warn_once("Unhandled hw breakpoint ops %d\n", ops);
+ return -EINVAL;
+ }
+ }
+ return -ENOSPC;
+}
+
+/*
+ * Unregister breakpoints from this task and reset the pointers in
+ * the thread_struct.
+ */
+void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
+{
+}
+
+void ptrace_hw_copy_thread(struct task_struct *tsk)
+{
+ memset(&tsk->thread.hbp_break, 0, sizeof(tsk->thread.hbp_break));
+ memset(&tsk->thread.hbp_watch, 0, sizeof(tsk->thread.hbp_watch));
+}
+
+static int hw_breakpoint_control(struct perf_event *bp,
+ enum hw_breakpoint_ops ops)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ struct perf_event **slots;
+ int i, max_slots, enable;
+ u32 ctrl;
+ struct pt_regs *regs = task_pt_regs(current);
+
+ if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
+ /* Breakpoint */
+ slots = this_cpu_ptr(bp_on_reg);
+ max_slots = core_num_brps;
+ } else {
+ /* Watchpoint */
+ slots = this_cpu_ptr(wp_on_reg);
+ max_slots = core_num_wrps;
+ }
+
+ i = hw_breakpoint_slot_setup(slots, max_slots, bp, ops);
+
+ if (WARN_ONCE(i < 0, "Can't find any breakpoint slot"))
+ return i;
+
+ switch (ops) {
+ case HW_BREAKPOINT_INSTALL:
+ /* Set the FWPnCFG/MWPnCFG 1~3 register. */
+ write_wb_reg(CSR_CFG_ADDR, i, 0, info->address);
+ write_wb_reg(CSR_CFG_ADDR, i, 1, info->address);
+ if (info->mask) {
+ write_wb_reg(CSR_CFG_MASK, i, 0, info->mask);
+ write_wb_reg(CSR_CFG_MASK, i, 1, info->mask);
+ }
+ write_wb_reg(CSR_CFG_ASID, i, 0, 0);
+ write_wb_reg(CSR_CFG_ASID, i, 1, 0);
+ ctrl = encode_ctrl_reg(info->ctrl);
+ if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE)
+ write_wb_reg(CSR_CFG_CTRL, i, 0, ctrl | 0x1e);
+ else
+ write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl | 0x1e | 1 << 8 | 1 << 9);
+
+ enable = csr_read64(LOONGARCH_CSR_CRMD);
+ csr_write64(1 << 9 | enable, LOONGARCH_CSR_CRMD);
+ break;
+ case HW_BREAKPOINT_UNINSTALL:
+ /* Reset the FWPnCFG/MWPnCFG 1~3 register. */
+ write_wb_reg(CSR_CFG_ADDR, i, 0, 0);
+ write_wb_reg(CSR_CFG_ADDR, i, 1, 0);
+ write_wb_reg(CSR_CFG_MASK, i, 0, 0);
+ write_wb_reg(CSR_CFG_MASK, i, 1, 0);
+ write_wb_reg(CSR_CFG_CTRL, i, 0, 0);
+ write_wb_reg(CSR_CFG_CTRL, i, 1, 0);
+ write_wb_reg(CSR_CFG_ASID, i, 0, 0);
+ write_wb_reg(CSR_CFG_ASID, i, 1, 0);
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * Install a perf counter breakpoint.
+ */
+int arch_install_hw_breakpoint(struct perf_event *bp)
+{
+ return hw_breakpoint_control(bp, HW_BREAKPOINT_INSTALL);
+}
+
+void arch_uninstall_hw_breakpoint(struct perf_event *bp)
+{
+ hw_breakpoint_control(bp, HW_BREAKPOINT_UNINSTALL);
+}
+
+static int get_hbp_len(u8 hbp_len)
+{
+ unsigned int len_in_bytes = 0;
+
+ switch (hbp_len) {
+ case LOONGARCH_BREAKPOINT_LEN_1:
+ len_in_bytes = 1;
+ break;
+ case LOONGARCH_BREAKPOINT_LEN_2:
+ len_in_bytes = 2;
+ break;
+ case LOONGARCH_BREAKPOINT_LEN_4:
+ len_in_bytes = 4;
+ break;
+ case LOONGARCH_BREAKPOINT_LEN_8:
+ len_in_bytes = 8;
+ break;
+ }
+
+ return len_in_bytes;
+}
+
+/*
+ * Check whether bp virtual address is in kernel space.
+ */
+int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw)
+{
+ unsigned int len;
+ unsigned long va;
+
+ va = hw->address;
+ len = get_hbp_len(hw->ctrl.len);
+
+ return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
+}
+
+/*
+ * Construct an arch_hw_breakpoint from a perf_event.
+ */
+static int arch_build_bp_info(struct perf_event *bp,
+ const struct perf_event_attr *attr,
+ struct arch_hw_breakpoint *hw)
+{
+ /* Type */
+ switch (attr->bp_type) {
+ case HW_BREAKPOINT_X:
+ hw->ctrl.type = LOONGARCH_BREAKPOINT_EXECUTE;
+ break;
+ case HW_BREAKPOINT_R:
+ hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD;
+ break;
+ case HW_BREAKPOINT_W:
+ hw->ctrl.type = LOONGARCH_BREAKPOINT_STORE;
+ break;
+ case HW_BREAKPOINT_RW:
+ hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD | LOONGARCH_BREAKPOINT_STORE;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /* Len */
+ switch (attr->bp_len) {
+ case HW_BREAKPOINT_LEN_1:
+ hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_1;
+ break;
+ case HW_BREAKPOINT_LEN_2:
+ hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_2;
+ break;
+ case HW_BREAKPOINT_LEN_4:
+ hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_4;
+ break;
+ case HW_BREAKPOINT_LEN_8:
+ hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_8;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /* Address */
+ hw->address = attr->bp_addr;
+
+ return 0;
+}
+
+/*
+ * Validate the arch-specific HW Breakpoint register settings.
+ */
+int hw_breakpoint_arch_parse(struct perf_event *bp,
+ const struct perf_event_attr *attr,
+ struct arch_hw_breakpoint *hw)
+{
+ int ret;
+ u64 alignment_mask, offset;
+
+ /* Build the arch_hw_breakpoint. */
+ ret = arch_build_bp_info(bp, attr, hw);
+ if (ret)
+ return ret;
+
+ if (hw->ctrl.type != LOONGARCH_BREAKPOINT_EXECUTE)
+ alignment_mask = 0x7;
+ offset = hw->address & alignment_mask;
+
+ hw->address &= ~alignment_mask;
+ hw->ctrl.len <<= offset;
+
+ return 0;
+}
+
+#define PRMD_WE (1UL<<3) /*prmd watch enable, restore to crmd when eret*/
+static void update_bp_registers(struct pt_regs *regs, int enable)
+{
+ int i, max_slots;
+ u32 ctrl;
+ struct perf_event **slots;
+
+ if (csr_read64(LOONGARCH_CSR_FWPS) & 0xff) {
+ slots = this_cpu_ptr(bp_on_reg);
+ max_slots = core_num_brps;
+
+ } else if (csr_read64(LOONGARCH_CSR_MWPS) & 0xff) {
+ slots = this_cpu_ptr(wp_on_reg);
+ max_slots = core_num_wrps;
+ } else {
+ return;
+ }
+
+ for (i = 0; i < max_slots; ++i) {
+ if (!slots[i])
+ continue;
+
+ ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
+ if (enable) {
+ ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
+ ctrl |= 0x1 << 8;
+ ctrl |= 0x1 << 9;
+ write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
+ regs->csr_prmd |= PRMD_WE;
+ } else {
+ ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
+ ctrl &= ~0x1 << 8;
+ ctrl &= ~0x1 << 9;
+ write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
+ regs->csr_prmd &= ~PRMD_WE;
+ }
+ }
+}
+NOKPROBE_SYMBOL(update_bp_registers);
+
+/*
+ * Debug exception handlers.
+ */
+int breakpoint_handler(struct pt_regs *regs)
+{
+ int i;
+ u64 addr;
+ struct perf_event *bp, **slots;
+
+ slots = this_cpu_ptr(bp_on_reg);
+
+ for (i = 0; i < core_num_brps; ++i) {
+ bp = slots[i];
+ if (bp == NULL)
+ continue;
+ perf_bp_event(bp, regs);
+ }
+ update_bp_registers(regs, 0);
+
+ return 0;
+}
+NOKPROBE_SYMBOL(breakpoint_handler);
+
+int watchpoint_handler(struct pt_regs *regs)
+{
+ int i;
+ struct perf_event *wp, **slots;
+
+ slots = this_cpu_ptr(wp_on_reg);
+
+ for (i = 0; i < core_num_wrps; ++i) {
+ wp = slots[i];
+ if (wp == NULL)
+ continue;
+ perf_bp_event(wp, regs);
+ }
+ update_bp_registers(regs, 0);
+
+ return 0;
+}
+NOKPROBE_SYMBOL(watchpoint_handler);
+
+/*
+ * One-time initialisation.
+ */
+static int __init arch_hw_breakpoint_init(void)
+{
+ core_num_brps = get_num_brps();
+ core_num_wrps = get_num_wrps();
+
+ pr_info("found %d breakpoint and %d watchpoint registers.\n",
+ core_num_brps, core_num_wrps);
+ return 0;
+}
+arch_initcall(arch_hw_breakpoint_init);
+
+void hw_breakpoint_thread_switch(struct task_struct *next)
+{
+ struct pt_regs *regs = task_pt_regs(next);
+
+ /* Update breakpoints/watchpoints. */
+ update_bp_registers(regs, 1);
+}
+
+void hw_breakpoint_pmu_read(struct perf_event *bp)
+{
+}
+
+/*
+ * Dummy function to register with die_notifier.
+ */
+int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
+ unsigned long val, void *data)
+{
+ return NOTIFY_DONE;
+}
diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c
index 27c8cacbce01..f78574562329 100644
--- a/arch/loongarch/kernel/process.c
+++ b/arch/loongarch/kernel/process.c
@@ -37,6 +37,7 @@
#include <asm/cpu.h>
#include <asm/elf.h>
#include <asm/fpu.h>
+#include <linux/hw_breakpoint.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/irq_regs.h>
@@ -100,6 +101,11 @@ void exit_thread(struct task_struct *tsk)
{
}
+void flush_thread(void)
+{
+ flush_ptrace_hw_breakpoint(current);
+}
+
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
/*
@@ -186,6 +192,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
if (clone_flags & CLONE_SETTLS)
childregs->regs[2] = tls;
+ ptrace_hw_copy_thread(p);
+
out:
clear_tsk_thread_flag(p, TIF_USEDFPU);
clear_tsk_thread_flag(p, TIF_USEDSIMD);
diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index 4d9f77565703..d59cf93a4c31 100644
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -45,6 +45,7 @@
#include <asm/tlb.h>
#include <asm/types.h>
#include <asm/unwind.h>
+#include <asm/hw_breakpoint.h>
#include "access-helper.h"
@@ -514,7 +515,19 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs)
asmlinkage void noinstr do_watch(struct pt_regs *regs)
{
- pr_warn("Hardware watch point handler not implemented!\n");
+ enum ctx_state prev_state;
+
+ prev_state = exception_enter();
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+ if (breakpoint_handler(regs))
+ return;
+ if (watchpoint_handler(regs))
+ return;
+#endif
+ force_sig(SIGTRAP);
+ exception_exit(prev_state);
+ return;
}
asmlinkage void noinstr do_ri(struct pt_regs *regs)
--
2.36.0
Hi, Qing,
As it is a big patch with RFC title, I'll provide some style idea firstly.
On 2022-12-13 17:10, qing zhang wrote:
> From: Qing Zhang <[email protected]>
>
> Use perf framework to manage hardware instruction and data breakpoints.
> LoongArch defines hardware watchpoint functions for instruction fetch
> and load/store operations, after the software configures hardware watchpoints
> for instruction fetch and load/store operations. The processor hardware will
> monitor the access address of the instruction fetch and load/store operation,
> and will trigger the exception of the watchpoint when it meets the conditions
> set by the watchpoint.
>
> The hardware monitoring points for instruction fetching and load/store operations
> each have a register for the overall configuration of all monitoring points,
> a register for recording the status of all monitoring points, and four registers
> required for configuration of each watchpoint individually.
>
> Watchpoint related control status register chapters:
> https://github.com/loongson/LoongArch-Documentation/releases/download/2022.08.12/
> LoongArch-Vol1-v1.02-CN.pdf
>
> Initial version has the following limitations:
> - userspace debug is not yet enabled: work on ptrace/gdb is in progress
> - no support for virtualization
>
> Despite missing userspace debug, initial implementation can be tested: e.g.
> see samples/hw_breakpoint and register_wide_hw_breakpoint.
>
> TODO:
> - Add Kernel tools that use hardware breakpoints: Kgdb, Ptrace
> - Add hardware breakpoints/watchpoints for gdb
>
> Signed-off-by: Qing Zhang <[email protected]>
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index 12571eedc488..69199812fe74 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -99,6 +99,7 @@ config LOONGARCH
> select HAVE_FUNCTION_GRAPH_TRACER
> select HAVE_FUNCTION_TRACER
> select HAVE_GENERIC_VDSO
> + select HAVE_HW_BREAKPOINT if PERF_EVENTS
> select HAVE_IOREMAP_PROT
> select HAVE_IRQ_EXIT_ON_IRQ_STACK
> select HAVE_IRQ_TIME_ACCOUNTING
> diff --git a/arch/loongarch/include/asm/hw_breakpoint.h b/arch/loongarch/include/asm/hw_breakpoint.h
> new file mode 100644
> index 000000000000..a57caf117960
> --- /dev/null
> +++ b/arch/loongarch/include/asm/hw_breakpoint.h
> @@ -0,0 +1,140 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +#ifndef __ASM_HW_BREAKPOINT_H
> +#define __ASM_HW_BREAKPOINT_H
> +
> +#include <asm/loongarch.h>
> +
> +#ifdef __KERNEL__
> +
> +/* Breakpoint */
> +#define LOONGARCH_BREAKPOINT_EXECUTE (0 << 0)
> +
> +/* Watchpoints */
> +#define LOONGARCH_BREAKPOINT_LOAD (1 << 0)
> +#define LOONGARCH_BREAKPOINT_STORE (1 << 1)
> +
> +struct arch_hw_breakpoint_ctrl {
> + u32 __reserved : 28,
> + type : 2,
> + len : 2;
> +};
It looks strange...
> +
> +struct arch_hw_breakpoint {
> + u64 address;
> + u64 mask;
> + struct arch_hw_breakpoint_ctrl ctrl;
> +};
> +
> +/* Lengths */
> +#define LOONGARCH_BREAKPOINT_LEN_1 0b11
> +#define LOONGARCH_BREAKPOINT_LEN_2 0b10
> +#define LOONGARCH_BREAKPOINT_LEN_4 0b01
> +#define LOONGARCH_BREAKPOINT_LEN_8 0b00
> +
> +/*
> + * Limits.
> + * Changing these will require modifications to the register accessors.
> + */
> +#define LOONGARCH_MAX_BRP 8
> +#define LOONGARCH_MAX_WRP 8
> +
> +/* Virtual debug register bases. */
> +#define CSR_CFG_ADDR 0
> +#define CSR_CFG_MASK (CSR_CFG_ADDR + LOONGARCH_MAX_BRP)
> +#define CSR_CFG_CTRL (CSR_CFG_MASK + LOONGARCH_MAX_BRP)
> +#define CSR_CFG_ASID (CSR_CFG_CTRL + LOONGARCH_MAX_WRP)
> +
> +/* Debug register names. */
> +#define LOONGARCH_CSR_NAME_ADDR ADDR
> +#define LOONGARCH_CSR_NAME_MASK MASK
> +#define LOONGARCH_CSR_NAME_CTRL CTRL
> +#define LOONGARCH_CSR_NAME_ASID ASID
> +
> +/* Accessor macros for the debug registers. */
> +#define LOONGARCH_CSR_READ(N, REG, T, VAL) \
> +do { \
> + if (T == 0) \
> + VAL = csr_read64(LOONGARCH_CSR_##IB##N##REG); \
> + else \
> + VAL = csr_read64(LOONGARCH_CSR_##DB##N##REG); \
> +} while (0)
> +
> +#define LOONGARCH_CSR_WRITE(N, REG, T, VAL) \
> +do { \
> + if (T == 0) \
> + csr_write64(VAL, LOONGARCH_CSR_##IB##N##REG); \
> + else \
> + csr_write64(VAL, LOONGARCH_CSR_##DB##N##REG); \
> +} while (0)
The LOONGARCH_CSR_{READ, WRITE} are generic. As they are used locally, I
think it's better to change their name.
> +
> +static inline u32 encode_ctrl_reg(struct arch_hw_breakpoint_ctrl ctrl)
> +{
> + u32 val = (ctrl.len << 2) | ctrl.type;
> +
> + return val;
> +}
> +
> +static inline void decode_ctrl_reg(u32 reg, struct arch_hw_breakpoint_ctrl *ctrl)
> +{
> + ctrl->type = reg & 0x3;
> + reg >>= 2;
> + ctrl->len = reg & 0x3;
> +}
Actually it is no need "& 0x3", but it is also OK and clear. How about
support macros like HW_MASK_{TYPE, LEN}, HW_SHFIT_{TYPE, LEN}?
> +
> +struct task_struct;
> +struct notifier_block;
> +struct perf_event_attr;
> +struct perf_event;
> +
> +extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
> + int *gen_len, int *gen_type, int *offset);
> +extern int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw);
> +extern int hw_breakpoint_arch_parse(struct perf_event *bp,
> + const struct perf_event_attr *attr,
> + struct arch_hw_breakpoint *hw);
> +extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
> + unsigned long val, void *data);
> +
> +extern int arch_install_hw_breakpoint(struct perf_event *bp);
> +extern void arch_uninstall_hw_breakpoint(struct perf_event *bp);
> +extern void hw_breakpoint_pmu_read(struct perf_event *bp);
> +extern int hw_breakpoint_slots(int type);
> +
> +int breakpoint_handler(struct pt_regs *regs);
> +int watchpoint_handler(struct pt_regs *regs);
> +
> +#ifdef CONFIG_HAVE_HW_BREAKPOINT
> +extern void hw_breakpoint_thread_switch(struct task_struct *next);
> +extern void ptrace_hw_copy_thread(struct task_struct *task);
> +#else
> +static inline void hw_breakpoint_thread_switch(struct task_struct *next)
> +{
> +}
> +static inline void ptrace_hw_copy_thread(struct task_struct *task)
> +{
> +}
> +#endif
> +
> +/* Determine number of BRP registers available. */
> +static inline int get_num_brps(void)
> +{
> + unsigned int ibcn;
> +
> + ibcn = csr_read64(LOONGARCH_CSR_FWPC) & 0x3f;
And give mask macro here, too, for readability improvement.
> + return ibcn;
> +}
> +
> +/* Determine number of WRP registers available. */
> +static inline int get_num_wrps(void)
> +{
> + unsigned int dbcn;
> +
> + dbcn = csr_read64(LOONGARCH_CSR_MWPC) & 0x3f;
> + return dbcn;
> +}
> +
> +#endif /* __KERNEL__ */
> +#endif /* __ASM_BREAKPOINT_H */
> diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
> index 7f8d57a61c8b..e9aed583a064 100644
> --- a/arch/loongarch/include/asm/loongarch.h
> +++ b/arch/loongarch/include/asm/loongarch.h
> @@ -970,42 +970,42 @@ static __always_inline void iocsr_write64(u64 val, u32 reg)
>
> #define LOONGARCH_CSR_DB0ADDR 0x310 /* data breakpoint 0 address */
> #define LOONGARCH_CSR_DB0MASK 0x311 /* data breakpoint 0 mask */
> -#define LOONGARCH_CSR_DB0CTL 0x312 /* data breakpoint 0 control */
> +#define LOONGARCH_CSR_DB0CTRL 0x312 /* data breakpoint 0 control */
> #define LOONGARCH_CSR_DB0ASID 0x313 /* data breakpoint 0 asid */
>
> #define LOONGARCH_CSR_DB1ADDR 0x318 /* data breakpoint 1 address */
> #define LOONGARCH_CSR_DB1MASK 0x319 /* data breakpoint 1 mask */
> -#define LOONGARCH_CSR_DB1CTL 0x31a /* data breakpoint 1 control */
> +#define LOONGARCH_CSR_DB1CTRL 0x31a /* data breakpoint 1 control */
> #define LOONGARCH_CSR_DB1ASID 0x31b /* data breakpoint 1 asid */
>
> #define LOONGARCH_CSR_DB2ADDR 0x320 /* data breakpoint 2 address */
> #define LOONGARCH_CSR_DB2MASK 0x321 /* data breakpoint 2 mask */
> -#define LOONGARCH_CSR_DB2CTL 0x322 /* data breakpoint 2 control */
> +#define LOONGARCH_CSR_DB2CTRL 0x322 /* data breakpoint 2 control */
> #define LOONGARCH_CSR_DB2ASID 0x323 /* data breakpoint 2 asid */
>
> #define LOONGARCH_CSR_DB3ADDR 0x328 /* data breakpoint 3 address */
> #define LOONGARCH_CSR_DB3MASK 0x329 /* data breakpoint 3 mask */
> -#define LOONGARCH_CSR_DB3CTL 0x32a /* data breakpoint 3 control */
> +#define LOONGARCH_CSR_DB3CTRL 0x32a /* data breakpoint 3 control */
> #define LOONGARCH_CSR_DB3ASID 0x32b /* data breakpoint 3 asid */
>
> #define LOONGARCH_CSR_DB4ADDR 0x330 /* data breakpoint 4 address */
> #define LOONGARCH_CSR_DB4MASK 0x331 /* data breakpoint 4 maks */
> -#define LOONGARCH_CSR_DB4CTL 0x332 /* data breakpoint 4 control */
> +#define LOONGARCH_CSR_DB4CTRL 0x332 /* data breakpoint 4 control */
> #define LOONGARCH_CSR_DB4ASID 0x333 /* data breakpoint 4 asid */
>
> #define LOONGARCH_CSR_DB5ADDR 0x338 /* data breakpoint 5 address */
> #define LOONGARCH_CSR_DB5MASK 0x339 /* data breakpoint 5 mask */
> -#define LOONGARCH_CSR_DB5CTL 0x33a /* data breakpoint 5 control */
> +#define LOONGARCH_CSR_DB5CTRL 0x33a /* data breakpoint 5 control */
> #define LOONGARCH_CSR_DB5ASID 0x33b /* data breakpoint 5 asid */
>
> #define LOONGARCH_CSR_DB6ADDR 0x340 /* data breakpoint 6 address */
> #define LOONGARCH_CSR_DB6MASK 0x341 /* data breakpoint 6 mask */
> -#define LOONGARCH_CSR_DB6CTL 0x342 /* data breakpoint 6 control */
> +#define LOONGARCH_CSR_DB6CTRL 0x342 /* data breakpoint 6 control */
> #define LOONGARCH_CSR_DB6ASID 0x343 /* data breakpoint 6 asid */
>
> #define LOONGARCH_CSR_DB7ADDR 0x348 /* data breakpoint 7 address */
> #define LOONGARCH_CSR_DB7MASK 0x349 /* data breakpoint 7 mask */
> -#define LOONGARCH_CSR_DB7CTL 0x34a /* data breakpoint 7 control */
> +#define LOONGARCH_CSR_DB7CTRL 0x34a /* data breakpoint 7 control */
> #define LOONGARCH_CSR_DB7ASID 0x34b /* data breakpoint 7 asid */
>
> #define LOONGARCH_CSR_FWPC 0x380 /* instruction breakpoint config */
> @@ -1013,42 +1013,42 @@ static __always_inline void iocsr_write64(u64 val, u32 reg)
>
> #define LOONGARCH_CSR_IB0ADDR 0x390 /* inst breakpoint 0 address */
> #define LOONGARCH_CSR_IB0MASK 0x391 /* inst breakpoint 0 mask */
> -#define LOONGARCH_CSR_IB0CTL 0x392 /* inst breakpoint 0 control */
> +#define LOONGARCH_CSR_IB0CTRL 0x392 /* inst breakpoint 0 control */
> #define LOONGARCH_CSR_IB0ASID 0x393 /* inst breakpoint 0 asid */
>
> #define LOONGARCH_CSR_IB1ADDR 0x398 /* inst breakpoint 1 address */
> #define LOONGARCH_CSR_IB1MASK 0x399 /* inst breakpoint 1 mask */
> -#define LOONGARCH_CSR_IB1CTL 0x39a /* inst breakpoint 1 control */
> +#define LOONGARCH_CSR_IB1CTRL 0x39a /* inst breakpoint 1 control */
> #define LOONGARCH_CSR_IB1ASID 0x39b /* inst breakpoint 1 asid */
>
> #define LOONGARCH_CSR_IB2ADDR 0x3a0 /* inst breakpoint 2 address */
> #define LOONGARCH_CSR_IB2MASK 0x3a1 /* inst breakpoint 2 mask */
> -#define LOONGARCH_CSR_IB2CTL 0x3a2 /* inst breakpoint 2 control */
> +#define LOONGARCH_CSR_IB2CTRL 0x3a2 /* inst breakpoint 2 control */
> #define LOONGARCH_CSR_IB2ASID 0x3a3 /* inst breakpoint 2 asid */
>
> #define LOONGARCH_CSR_IB3ADDR 0x3a8 /* inst breakpoint 3 address */
> #define LOONGARCH_CSR_IB3MASK 0x3a9 /* breakpoint 3 mask */
> -#define LOONGARCH_CSR_IB3CTL 0x3aa /* inst breakpoint 3 control */
> +#define LOONGARCH_CSR_IB3CTRL 0x3aa /* inst breakpoint 3 control */
> #define LOONGARCH_CSR_IB3ASID 0x3ab /* inst breakpoint 3 asid */
>
> #define LOONGARCH_CSR_IB4ADDR 0x3b0 /* inst breakpoint 4 address */
> #define LOONGARCH_CSR_IB4MASK 0x3b1 /* inst breakpoint 4 mask */
> -#define LOONGARCH_CSR_IB4CTL 0x3b2 /* inst breakpoint 4 control */
> +#define LOONGARCH_CSR_IB4CTRL 0x3b2 /* inst breakpoint 4 control */
> #define LOONGARCH_CSR_IB4ASID 0x3b3 /* inst breakpoint 4 asid */
>
> #define LOONGARCH_CSR_IB5ADDR 0x3b8 /* inst breakpoint 5 address */
> #define LOONGARCH_CSR_IB5MASK 0x3b9 /* inst breakpoint 5 mask */
> -#define LOONGARCH_CSR_IB5CTL 0x3ba /* inst breakpoint 5 control */
> +#define LOONGARCH_CSR_IB5CTRL 0x3ba /* inst breakpoint 5 control */
> #define LOONGARCH_CSR_IB5ASID 0x3bb /* inst breakpoint 5 asid */
>
> #define LOONGARCH_CSR_IB6ADDR 0x3c0 /* inst breakpoint 6 address */
> #define LOONGARCH_CSR_IB6MASK 0x3c1 /* inst breakpoint 6 mask */
> -#define LOONGARCH_CSR_IB6CTL 0x3c2 /* inst breakpoint 6 control */
> +#define LOONGARCH_CSR_IB6CTRL 0x3c2 /* inst breakpoint 6 control */
> #define LOONGARCH_CSR_IB6ASID 0x3c3 /* inst breakpoint 6 asid */
>
> #define LOONGARCH_CSR_IB7ADDR 0x3c8 /* inst breakpoint 7 address */
> #define LOONGARCH_CSR_IB7MASK 0x3c9 /* inst breakpoint 7 mask */
> -#define LOONGARCH_CSR_IB7CTL 0x3ca /* inst breakpoint 7 control */
> +#define LOONGARCH_CSR_IB7CTRL 0x3ca /* inst breakpoint 7 control */
> #define LOONGARCH_CSR_IB7ASID 0x3cb /* inst breakpoint 7 asid */
>
> #define LOONGARCH_CSR_DEBUG 0x500 /* debug config */
> diff --git a/arch/loongarch/include/asm/processor.h b/arch/loongarch/include/asm/processor.h
> index 7184f1dc61f2..f6ee920122d6 100644
> --- a/arch/loongarch/include/asm/processor.h
> +++ b/arch/loongarch/include/asm/processor.h
> @@ -11,6 +11,7 @@
>
> #include <asm/cpu.h>
> #include <asm/cpu-info.h>
> +#include <asm/hw_breakpoint.h>
> #include <asm/loongarch.h>
> #include <asm/vdso/processor.h>
> #include <uapi/asm/ptrace.h>
> @@ -131,6 +132,9 @@ struct thread_struct {
> * they are conditionally copied at fork().
> */
> struct loongarch_fpu fpu FPU_ALIGN;
> + /* Hardware breakpoints pinned to this task. */
> + struct perf_event *hbp_break[LOONGARCH_MAX_BRP];
> + struct perf_event *hbp_watch[LOONGARCH_MAX_WRP];
> };
>
> #define thread_saved_ra(tsk) (tsk->thread.sched_ra)
> @@ -172,6 +176,8 @@ struct thread_struct {
> .fcc = 0, \
> .fpr = {{{0,},},}, \
> }, \
> + .hbp_break = {0}, \
> + .hbp_watch = {0}, \
> }
>
> struct task_struct;
> @@ -184,10 +190,6 @@ extern unsigned long boot_option_idle_override;
> */
> extern void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp);
>
> -static inline void flush_thread(void)
> -{
> -}
> -
> unsigned long __get_wchan(struct task_struct *p);
>
> #define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
> diff --git a/arch/loongarch/include/asm/switch_to.h b/arch/loongarch/include/asm/switch_to.h
> index 43a5ab162d38..24e3094bebab 100644
> --- a/arch/loongarch/include/asm/switch_to.h
> +++ b/arch/loongarch/include/asm/switch_to.h
> @@ -34,6 +34,7 @@ extern asmlinkage struct task_struct *__switch_to(struct task_struct *prev,
> #define switch_to(prev, next, last) \
> do { \
> lose_fpu_inatomic(1, prev); \
> + hw_breakpoint_thread_switch(next); \
> (last) = __switch_to(prev, next, task_thread_info(next), \
> __builtin_return_address(0), __builtin_frame_address(0)); \
> } while (0)
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> index 7ca65195f7f8..b3aca7f2296e 100644
> --- a/arch/loongarch/kernel/Makefile
> +++ b/arch/loongarch/kernel/Makefile
> @@ -46,6 +46,7 @@ obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
> obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
>
> obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
> +obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
>
> obj-$(CONFIG_KPROBES) += kprobes.o kprobes_trampoline.o
>
> diff --git a/arch/loongarch/kernel/hw_breakpoint.c b/arch/loongarch/kernel/hw_breakpoint.c
> new file mode 100644
> index 000000000000..16f38ceec321
> --- /dev/null
> +++ b/arch/loongarch/kernel/hw_breakpoint.c
> @@ -0,0 +1,461 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +#define pr_fmt(fmt) "hw-breakpoint: " fmt
> +
> +#include <linux/hw_breakpoint.h>
> +#include <linux/kprobes.h>
> +#include <linux/perf_event.h>
> +
> +#include <asm/hw_breakpoint.h>
> +
> +/* Breakpoint currently in use for each BRP. */
> +static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[LOONGARCH_MAX_BRP]);
> +
> +/* Watchpoint currently in use for each WRP. */
> +static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[LOONGARCH_MAX_WRP]);
> +
> +/* Number of BRP/WRP registers on this CPU. */
> +static int core_num_brps;
> +static int core_num_wrps;
> +
> +int hw_breakpoint_slots(int type)
> +{
> + /*
> + * We can be called early, so don't rely on
> + * our static variables being initialised.
> + */
> + switch (type) {
> + case TYPE_INST:
> + return get_num_brps();
> + case TYPE_DATA:
> + return get_num_wrps();
> + default:
> + pr_warn("unknown slot type: %d\n", type);
> + return 0;
> + }
> +}
> +
> +#define READ_WB_REG_CASE(OFF, N, REG, T, VAL) \
> + case (OFF + N): \
> + LOONGARCH_CSR_READ(N, REG, T, VAL); \
> + break
> +
> +#define WRITE_WB_REG_CASE(OFF, N, REG, T, VAL) \
> + case (OFF + N): \
> + LOONGARCH_CSR_WRITE(N, REG, T, VAL); \
> + break
> +
> +#define GEN_READ_WB_REG_CASES(OFF, REG, T, VAL) \
> + READ_WB_REG_CASE(OFF, 0, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 1, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 2, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 3, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 4, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 5, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 6, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 7, REG, T, VAL);
> +
> +#define GEN_WRITE_WB_REG_CASES(OFF, REG, T, VAL) \
> + WRITE_WB_REG_CASE(OFF, 0, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 1, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 2, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 3, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 4, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 5, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 6, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 7, REG, T, VAL);
> +
> +static u64 read_wb_reg(int reg, int n, int t)
> +{
> + u64 val = 0;
> +
> + switch (reg + n) {
> + GEN_READ_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
> + GEN_READ_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
> + GEN_READ_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
> + GEN_READ_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
> + default:
> + pr_warn("attempt to read from unknown breakpoint register %d\n", n);
> + }
> +
> + return val;
> +}
> +NOKPROBE_SYMBOL(read_wb_reg);
> +
> +static void write_wb_reg(int reg, int n, int t, u64 val)
> +{
> + switch (reg + n) {
> + GEN_WRITE_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
> + GEN_WRITE_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
> + GEN_WRITE_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
> + GEN_WRITE_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
> + default:
> + pr_warn("attempt to write to unknown breakpoint register %d\n", n);
> + }
> +}
> +NOKPROBE_SYMBOL(write_wb_reg);
> +
> +enum hw_breakpoint_ops {
> + HW_BREAKPOINT_INSTALL,
> + HW_BREAKPOINT_UNINSTALL,
> +};
> +
> +/**
> + * hw_breakpoint_slot_setup - Find and setup a perf slot according to
> + * operations
> + *
> + * @slots: pointer to array of slots
> + * @max_slots: max number of slots
> + * @bp: perf_event to setup
> + * @ops: operation to be carried out on the slot
> + *
> + * Return:
> + * slot index on success
> + * -ENOSPC if no slot is available/matches
> + * -EINVAL on wrong operations parameter
> + */
> +static int hw_breakpoint_slot_setup(struct perf_event **slots, int max_slots,
> + struct perf_event *bp,
> + enum hw_breakpoint_ops ops)
> +{
> + int i;
> + struct perf_event **slot;
> +
> + for (i = 0; i < max_slots; ++i) {
> + slot = &slots[i];
> + switch (ops) {
> + case HW_BREAKPOINT_INSTALL:
> + if (!*slot) {
> + *slot = bp;
> + return i;
> + }
> + break;
> + case HW_BREAKPOINT_UNINSTALL:
> + if (*slot == bp) {
> + *slot = NULL;
> + return i;
> + }
> + break;
> + default:
> + pr_warn_once("Unhandled hw breakpoint ops %d\n", ops);
> + return -EINVAL;
> + }
> + }
> + return -ENOSPC;
> +}
> +
> +/*
> + * Unregister breakpoints from this task and reset the pointers in
> + * the thread_struct.
> + */
> +void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
> +{
> +}
> +
> +void ptrace_hw_copy_thread(struct task_struct *tsk)
> +{
> + memset(&tsk->thread.hbp_break, 0, sizeof(tsk->thread.hbp_break));
> + memset(&tsk->thread.hbp_watch, 0, sizeof(tsk->thread.hbp_watch));
> +}
> +
> +static int hw_breakpoint_control(struct perf_event *bp,
> + enum hw_breakpoint_ops ops)
> +{
> + struct arch_hw_breakpoint *info = counter_arch_bp(bp);
> + struct perf_event **slots;
> + int i, max_slots, enable;
> + u32 ctrl;
> + struct pt_regs *regs = task_pt_regs(current);
> +
> + if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
> + /* Breakpoint */
> + slots = this_cpu_ptr(bp_on_reg);
> + max_slots = core_num_brps;
> + } else {
> + /* Watchpoint */
> + slots = this_cpu_ptr(wp_on_reg);
> + max_slots = core_num_wrps;
> + }
> +
> + i = hw_breakpoint_slot_setup(slots, max_slots, bp, ops);
> +
> + if (WARN_ONCE(i < 0, "Can't find any breakpoint slot"))
> + return i;
> +
> + switch (ops) {
> + case HW_BREAKPOINT_INSTALL:
> + /* Set the FWPnCFG/MWPnCFG 1~3 register. */
> + write_wb_reg(CSR_CFG_ADDR, i, 0, info->address);
> + write_wb_reg(CSR_CFG_ADDR, i, 1, info->address);
> + if (info->mask) {
> + write_wb_reg(CSR_CFG_MASK, i, 0, info->mask);
> + write_wb_reg(CSR_CFG_MASK, i, 1, info->mask);
> + }
> + write_wb_reg(CSR_CFG_ASID, i, 0, 0);
> + write_wb_reg(CSR_CFG_ASID, i, 1, 0);
> + ctrl = encode_ctrl_reg(info->ctrl);
> + if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE)
> + write_wb_reg(CSR_CFG_CTRL, i, 0, ctrl | 0x1e);
> + else
> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl | 0x1e | 1 << 8 | 1 << 9);
> +
> + enable = csr_read64(LOONGARCH_CSR_CRMD);
> + csr_write64(1 << 9 | enable, LOONGARCH_CSR_CRMD);
> + break;
> + case HW_BREAKPOINT_UNINSTALL:
> + /* Reset the FWPnCFG/MWPnCFG 1~3 register. */
> + write_wb_reg(CSR_CFG_ADDR, i, 0, 0);
> + write_wb_reg(CSR_CFG_ADDR, i, 1, 0);
> + write_wb_reg(CSR_CFG_MASK, i, 0, 0);
> + write_wb_reg(CSR_CFG_MASK, i, 1, 0);
> + write_wb_reg(CSR_CFG_CTRL, i, 0, 0);
> + write_wb_reg(CSR_CFG_CTRL, i, 1, 0);
> + write_wb_reg(CSR_CFG_ASID, i, 0, 0);
> + write_wb_reg(CSR_CFG_ASID, i, 1, 0);
> + break;
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * Install a perf counter breakpoint.
> + */
> +int arch_install_hw_breakpoint(struct perf_event *bp)
> +{
> + return hw_breakpoint_control(bp, HW_BREAKPOINT_INSTALL);
> +}
> +
> +void arch_uninstall_hw_breakpoint(struct perf_event *bp)
> +{
> + hw_breakpoint_control(bp, HW_BREAKPOINT_UNINSTALL);
> +}
> +
> +static int get_hbp_len(u8 hbp_len)
An array for simplify.
> +{
> + unsigned int len_in_bytes = 0;
> +
> + switch (hbp_len) {
> + case LOONGARCH_BREAKPOINT_LEN_1:
> + len_in_bytes = 1;
> + break;
> + case LOONGARCH_BREAKPOINT_LEN_2:
> + len_in_bytes = 2;
> + break;
> + case LOONGARCH_BREAKPOINT_LEN_4:
> + len_in_bytes = 4;
> + break;
> + case LOONGARCH_BREAKPOINT_LEN_8:
> + len_in_bytes = 8;
> + break;
> + }
> +
> + return len_in_bytes;
> +}
> +
> +/*
> + * Check whether bp virtual address is in kernel space.
> + */
> +int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw)
> +{
> + unsigned int len;
> + unsigned long va;
> +
> + va = hw->address;
> + len = get_hbp_len(hw->ctrl.len);
> +
> + return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
> +}
> +
> +/*
> + * Construct an arch_hw_breakpoint from a perf_event.
> + */
> +static int arch_build_bp_info(struct perf_event *bp,
> + const struct perf_event_attr *attr,
> + struct arch_hw_breakpoint *hw)
> +{
> + /* Type */
> + switch (attr->bp_type) {
> + case HW_BREAKPOINT_X:
> + hw->ctrl.type = LOONGARCH_BREAKPOINT_EXECUTE;
> + break;
> + case HW_BREAKPOINT_R:
> + hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD;
> + break;
> + case HW_BREAKPOINT_W:
> + hw->ctrl.type = LOONGARCH_BREAKPOINT_STORE;
> + break;
> + case HW_BREAKPOINT_RW:
> + hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD | LOONGARCH_BREAKPOINT_STORE;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + /* Len */
> + switch (attr->bp_len) {
> + case HW_BREAKPOINT_LEN_1:
> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_1;
> + break;
> + case HW_BREAKPOINT_LEN_2:
> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_2;
> + break;
> + case HW_BREAKPOINT_LEN_4:
> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_4;
> + break;
> + case HW_BREAKPOINT_LEN_8:
> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_8;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + /* Address */
> + hw->address = attr->bp_addr;
> +
> + return 0;
> +}
> +
> +/*
> + * Validate the arch-specific HW Breakpoint register settings.
> + */
> +int hw_breakpoint_arch_parse(struct perf_event *bp,
> + const struct perf_event_attr *attr,
> + struct arch_hw_breakpoint *hw)
> +{
> + int ret;
> + u64 alignment_mask, offset;
> +
> + /* Build the arch_hw_breakpoint. */
> + ret = arch_build_bp_info(bp, attr, hw);
> + if (ret)
> + return ret;
> +
> + if (hw->ctrl.type != LOONGARCH_BREAKPOINT_EXECUTE)
> + alignment_mask = 0x7;
> + offset = hw->address & alignment_mask;
> +
> + hw->address &= ~alignment_mask;
> + hw->ctrl.len <<= offset;
> +
> + return 0;
> +}
> +
> +#define PRMD_WE (1UL<<3) /*prmd watch enable, restore to crmd when eret*/
> +static void update_bp_registers(struct pt_regs *regs, int enable)
Use macro in this function for ...
> +{
> + int i, max_slots;
> + u32 ctrl;
> + struct perf_event **slots;
> +
> + if (csr_read64(LOONGARCH_CSR_FWPS) & 0xff) {
> + slots = this_cpu_ptr(bp_on_reg);
> + max_slots = core_num_brps;
> +
> + } else if (csr_read64(LOONGARCH_CSR_MWPS) & 0xff) {
> + slots = this_cpu_ptr(wp_on_reg);
> + max_slots = core_num_wrps;
> + } else {
> + return;
> + }
> +
> + for (i = 0; i < max_slots; ++i) {
> + if (!slots[i])
> + continue;
> +
> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
> + if (enable) {
> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
> + ctrl |= 0x1 << 8;
> + ctrl |= 0x1 << 9;
> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
> + regs->csr_prmd |= PRMD_WE;
> + } else {
> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
> + ctrl &= ~0x1 << 8;
> + ctrl &= ~0x1 << 9;
> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
> + regs->csr_prmd &= ~PRMD_WE;
> + }
> + }
> +}
> +NOKPROBE_SYMBOL(update_bp_registers);
> +
> +/*
> + * Debug exception handlers.
> + */
> +int breakpoint_handler(struct pt_regs *regs)
> +{
> + int i;
> + u64 addr;
> + struct perf_event *bp, **slots;
> +
> + slots = this_cpu_ptr(bp_on_reg);
> +
> + for (i = 0; i < core_num_brps; ++i) {
> + bp = slots[i];
> + if (bp == NULL)
> + continue;
> + perf_bp_event(bp, regs);
> + }
> + update_bp_registers(regs, 0);
> +
> + return 0;
> +}
> +NOKPROBE_SYMBOL(breakpoint_handler);
> +
> +int watchpoint_handler(struct pt_regs *regs)
> +{
> + int i;
> + struct perf_event *wp, **slots;
> +
> + slots = this_cpu_ptr(wp_on_reg);
> +
> + for (i = 0; i < core_num_wrps; ++i) {
> + wp = slots[i];
> + if (wp == NULL)
> + continue;
> + perf_bp_event(wp, regs);
> + }
> + update_bp_registers(regs, 0);
> +
> + return 0;
> +}
> +NOKPROBE_SYMBOL(watchpoint_handler);
> +
> +/*
> + * One-time initialisation.
> + */
> +static int __init arch_hw_breakpoint_init(void)
> +{
> + core_num_brps = get_num_brps();
> + core_num_wrps = get_num_wrps();
> +
> + pr_info("found %d breakpoint and %d watchpoint registers.\n",
> + core_num_brps, core_num_wrps);
> + return 0;
> +}
> +arch_initcall(arch_hw_breakpoint_init);
> +
> +void hw_breakpoint_thread_switch(struct task_struct *next)
> +{
> + struct pt_regs *regs = task_pt_regs(next);
> +
> + /* Update breakpoints/watchpoints. */
> + update_bp_registers(regs, 1);
> +}
> +
> +void hw_breakpoint_pmu_read(struct perf_event *bp)
> +{
> +}
> +
> +/*
> + * Dummy function to register with die_notifier.
> + */
> +int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
> + unsigned long val, void *data)
> +{
> + return NOTIFY_DONE;
> +}
> diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c
> index 27c8cacbce01..f78574562329 100644
> --- a/arch/loongarch/kernel/process.c
> +++ b/arch/loongarch/kernel/process.c
> @@ -37,6 +37,7 @@
> #include <asm/cpu.h>
> #include <asm/elf.h>
> #include <asm/fpu.h>
> +#include <linux/hw_breakpoint.h>
...
> #include <asm/io.h>
> #include <asm/irq.h>
> #include <asm/irq_regs.h>
> @@ -100,6 +101,11 @@ void exit_thread(struct task_struct *tsk)
> {
> }
>
> +void flush_thread(void)
> +{
> + flush_ptrace_hw_breakpoint(current);
> +}
> +
> int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
> {
> /*
> @@ -186,6 +192,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
> if (clone_flags & CLONE_SETTLS)
> childregs->regs[2] = tls;
>
> + ptrace_hw_copy_thread(p);
> +
> out:
> clear_tsk_thread_flag(p, TIF_USEDFPU);
> clear_tsk_thread_flag(p, TIF_USEDSIMD);
> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
> index 4d9f77565703..d59cf93a4c31 100644
> --- a/arch/loongarch/kernel/traps.c
> +++ b/arch/loongarch/kernel/traps.c
> @@ -45,6 +45,7 @@
> #include <asm/tlb.h>
> #include <asm/types.h>
> #include <asm/unwind.h>
> +#include <asm/hw_breakpoint.h>
>
> #include "access-helper.h"
>
> @@ -514,7 +515,19 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs)
>
> asmlinkage void noinstr do_watch(struct pt_regs *regs)
> {
> - pr_warn("Hardware watch point handler not implemented!\n");
> + enum ctx_state prev_state;
> +
> + prev_state = exception_enter();
> +
> +#ifdef CONFIG_HAVE_HW_BREAKPOINT
> + if (breakpoint_handler(regs))
> + return;
> + if (watchpoint_handler(regs))
> + return;
> +#endif
> + force_sig(SIGTRAP);
> + exception_exit(prev_state);
> + return;
> }
>
> asmlinkage void noinstr do_ri(struct pt_regs *regs)
Thanks,
jinyang
Hi, Jinyang
On 2022/12/13 下午7:55, Jinyang He wrote:
> Hi, Qing,
>
>
> As it is a big patch with RFC title, I'll provide some style idea firstly.
>
>
> On 2022-12-13 17:10, qing zhang wrote:
>> From: Qing Zhang <[email protected]>
>>
>> Use perf framework to manage hardware instruction and data breakpoints.
>> LoongArch defines hardware watchpoint functions for instruction fetch
>> and load/store operations, after the software configures hardware
>> watchpoints
>> for instruction fetch and load/store operations. The processor
>> hardware will
>> monitor the access address of the instruction fetch and load/store
>> operation,
>> and will trigger the exception of the watchpoint when it meets the
>> conditions
>> set by the watchpoint.
>>
>> The hardware monitoring points for instruction fetching and load/store
>> operations
>> each have a register for the overall configuration of all monitoring
>> points,
>> a register for recording the status of all monitoring points, and four
>> registers
>> required for configuration of each watchpoint individually.
>>
>> Watchpoint related control status register chapters:
>> https://github.com/loongson/LoongArch-Documentation/releases/download/2022.08.12/
>>
>> LoongArch-Vol1-v1.02-CN.pdf
>>
>> Initial version has the following limitations:
>> - userspace debug is not yet enabled: work on ptrace/gdb is in progress
>> - no support for virtualization
>>
>> Despite missing userspace debug, initial implementation can be tested:
>> e.g.
>> see samples/hw_breakpoint and register_wide_hw_breakpoint.
>>
>> TODO:
>> - Add Kernel tools that use hardware breakpoints: Kgdb, Ptrace
>> - Add hardware breakpoints/watchpoints for gdb
>>
>> Signed-off-by: Qing Zhang <[email protected]>
>>
>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
>> index 12571eedc488..69199812fe74 100644
>> --- a/arch/loongarch/Kconfig
>> +++ b/arch/loongarch/Kconfig
>> @@ -99,6 +99,7 @@ config LOONGARCH
>> select HAVE_FUNCTION_GRAPH_TRACER
>> select HAVE_FUNCTION_TRACER
>> select HAVE_GENERIC_VDSO
>> + select HAVE_HW_BREAKPOINT if PERF_EVENTS
>> select HAVE_IOREMAP_PROT
>> select HAVE_IRQ_EXIT_ON_IRQ_STACK
>> select HAVE_IRQ_TIME_ACCOUNTING
>> diff --git a/arch/loongarch/include/asm/hw_breakpoint.h
>> b/arch/loongarch/include/asm/hw_breakpoint.h
>> new file mode 100644
>> index 000000000000..a57caf117960
>> --- /dev/null
>> +++ b/arch/loongarch/include/asm/hw_breakpoint.h
>> @@ -0,0 +1,140 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>> + */
>> +#ifndef __ASM_HW_BREAKPOINT_H
>> +#define __ASM_HW_BREAKPOINT_H
>> +
>> +#include <asm/loongarch.h>
>> +
>> +#ifdef __KERNEL__
>> +
>> +/* Breakpoint */
>> +#define LOONGARCH_BREAKPOINT_EXECUTE (0 << 0)
>> +
>> +/* Watchpoints */
>> +#define LOONGARCH_BREAKPOINT_LOAD (1 << 0)
>> +#define LOONGARCH_BREAKPOINT_STORE (1 << 1)
>> +
>> +struct arch_hw_breakpoint_ctrl {
>> + u32 __reserved : 28,
>> + type : 2,
>> + len : 2;
>> +};
> It looks strange...
>> +
>> +struct arch_hw_breakpoint {
>> + u64 address;
>> + u64 mask;
>> + struct arch_hw_breakpoint_ctrl ctrl;
>> +};
>> +
>> +/* Lengths */
>> +#define LOONGARCH_BREAKPOINT_LEN_1 0b11
>> +#define LOONGARCH_BREAKPOINT_LEN_2 0b10
>> +#define LOONGARCH_BREAKPOINT_LEN_4 0b01
>> +#define LOONGARCH_BREAKPOINT_LEN_8 0b00
>> +
>> +/*
>> + * Limits.
>> + * Changing these will require modifications to the register accessors.
>> + */
>> +#define LOONGARCH_MAX_BRP 8
>> +#define LOONGARCH_MAX_WRP 8
>> +
>> +/* Virtual debug register bases. */
>> +#define CSR_CFG_ADDR 0
>> +#define CSR_CFG_MASK (CSR_CFG_ADDR + LOONGARCH_MAX_BRP)
>> +#define CSR_CFG_CTRL (CSR_CFG_MASK + LOONGARCH_MAX_BRP)
>> +#define CSR_CFG_ASID (CSR_CFG_CTRL + LOONGARCH_MAX_WRP)
>> +
>> +/* Debug register names. */
>> +#define LOONGARCH_CSR_NAME_ADDR ADDR
>> +#define LOONGARCH_CSR_NAME_MASK MASK
>> +#define LOONGARCH_CSR_NAME_CTRL CTRL
>> +#define LOONGARCH_CSR_NAME_ASID ASID
>> +
>> +/* Accessor macros for the debug registers. */
>> +#define LOONGARCH_CSR_READ(N, REG, T, VAL) \
>> +do { \
>> + if (T == 0) \
>> + VAL = csr_read64(LOONGARCH_CSR_##IB##N##REG); \
>> + else \
>> + VAL = csr_read64(LOONGARCH_CSR_##DB##N##REG); \
>> +} while (0)
>> +
>> +#define LOONGARCH_CSR_WRITE(N, REG, T, VAL) \
>> +do { \
>> + if (T == 0) \
>> + csr_write64(VAL, LOONGARCH_CSR_##IB##N##REG); \
>> + else \
>> + csr_write64(VAL, LOONGARCH_CSR_##DB##N##REG); \
>> +} while (0)
> The LOONGARCH_CSR_{READ, WRITE} are generic. As they are used locally, I
> think it's better to change their name.
>> +
>> +static inline u32 encode_ctrl_reg(struct arch_hw_breakpoint_ctrl ctrl)
>> +{
>> + u32 val = (ctrl.len << 2) | ctrl.type;
>> +
>> + return val;
>> +}
>> +
>> +static inline void decode_ctrl_reg(u32 reg, struct
>> arch_hw_breakpoint_ctrl *ctrl)
>> +{
>> + ctrl->type = reg & 0x3;
>> + reg >>= 2;
>> + ctrl->len = reg & 0x3;
>> +}
> Actually it is no need "& 0x3", but it is also OK and clear. How about
> support macros like HW_MASK_{TYPE, LEN}, HW_SHFIT_{TYPE, LEN}?
>> +
>> +struct task_struct;
>> +struct notifier_block;
>> +struct perf_event_attr;
>> +struct perf_event;
>> +
>> +extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
>> + int *gen_len, int *gen_type, int *offset);
>> +extern int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw);
>> +extern int hw_breakpoint_arch_parse(struct perf_event *bp,
>> + const struct perf_event_attr *attr,
>> + struct arch_hw_breakpoint *hw);
>> +extern int hw_breakpoint_exceptions_notify(struct notifier_block
>> *unused,
>> + unsigned long val, void *data);
>> +
>> +extern int arch_install_hw_breakpoint(struct perf_event *bp);
>> +extern void arch_uninstall_hw_breakpoint(struct perf_event *bp);
>> +extern void hw_breakpoint_pmu_read(struct perf_event *bp);
>> +extern int hw_breakpoint_slots(int type);
>> +
>> +int breakpoint_handler(struct pt_regs *regs);
>> +int watchpoint_handler(struct pt_regs *regs);
>> +
>> +#ifdef CONFIG_HAVE_HW_BREAKPOINT
>> +extern void hw_breakpoint_thread_switch(struct task_struct *next);
>> +extern void ptrace_hw_copy_thread(struct task_struct *task);
>> +#else
>> +static inline void hw_breakpoint_thread_switch(struct task_struct *next)
>> +{
>> +}
>> +static inline void ptrace_hw_copy_thread(struct task_struct *task)
>> +{
>> +}
>> +#endif
>> +
>> +/* Determine number of BRP registers available. */
>> +static inline int get_num_brps(void)
>> +{
>> + unsigned int ibcn;
>> +
>> + ibcn = csr_read64(LOONGARCH_CSR_FWPC) & 0x3f;
> And give mask macro here, too, for readability improvement.
>> + return ibcn;
>> +}
>> +
>> +/* Determine number of WRP registers available. */
>> +static inline int get_num_wrps(void)
>> +{
>> + unsigned int dbcn;
>> +
>> + dbcn = csr_read64(LOONGARCH_CSR_MWPC) & 0x3f;
>> + return dbcn;
>> +}
>> +
>> +#endif /* __KERNEL__ */
>> +#endif /* __ASM_BREAKPOINT_H */
>> diff --git a/arch/loongarch/include/asm/loongarch.h
>> b/arch/loongarch/include/asm/loongarch.h
>> index 7f8d57a61c8b..e9aed583a064 100644
>> --- a/arch/loongarch/include/asm/loongarch.h
>> +++ b/arch/loongarch/include/asm/loongarch.h
>> @@ -970,42 +970,42 @@ static __always_inline void iocsr_write64(u64
>> val, u32 reg)
>> #define LOONGARCH_CSR_DB0ADDR 0x310 /* data breakpoint 0
>> address */
>> #define LOONGARCH_CSR_DB0MASK 0x311 /* data breakpoint 0
>> mask */
>> -#define LOONGARCH_CSR_DB0CTL 0x312 /* data breakpoint 0
>> control */
>> +#define LOONGARCH_CSR_DB0CTRL 0x312 /* data breakpoint 0
>> control */
>> #define LOONGARCH_CSR_DB0ASID 0x313 /* data breakpoint 0
>> asid */
>> #define LOONGARCH_CSR_DB1ADDR 0x318 /* data breakpoint 1
>> address */
>> #define LOONGARCH_CSR_DB1MASK 0x319 /* data breakpoint 1
>> mask */
>> -#define LOONGARCH_CSR_DB1CTL 0x31a /* data breakpoint 1
>> control */
>> +#define LOONGARCH_CSR_DB1CTRL 0x31a /* data breakpoint 1
>> control */
>> #define LOONGARCH_CSR_DB1ASID 0x31b /* data breakpoint 1
>> asid */
>> #define LOONGARCH_CSR_DB2ADDR 0x320 /* data breakpoint 2
>> address */
>> #define LOONGARCH_CSR_DB2MASK 0x321 /* data breakpoint 2
>> mask */
>> -#define LOONGARCH_CSR_DB2CTL 0x322 /* data breakpoint 2
>> control */
>> +#define LOONGARCH_CSR_DB2CTRL 0x322 /* data breakpoint 2
>> control */
>> #define LOONGARCH_CSR_DB2ASID 0x323 /* data breakpoint 2
>> asid */
>> #define LOONGARCH_CSR_DB3ADDR 0x328 /* data breakpoint 3
>> address */
>> #define LOONGARCH_CSR_DB3MASK 0x329 /* data breakpoint 3
>> mask */
>> -#define LOONGARCH_CSR_DB3CTL 0x32a /* data breakpoint 3
>> control */
>> +#define LOONGARCH_CSR_DB3CTRL 0x32a /* data breakpoint 3
>> control */
>> #define LOONGARCH_CSR_DB3ASID 0x32b /* data breakpoint 3
>> asid */
>> #define LOONGARCH_CSR_DB4ADDR 0x330 /* data breakpoint 4
>> address */
>> #define LOONGARCH_CSR_DB4MASK 0x331 /* data breakpoint 4
>> maks */
>> -#define LOONGARCH_CSR_DB4CTL 0x332 /* data breakpoint 4
>> control */
>> +#define LOONGARCH_CSR_DB4CTRL 0x332 /* data breakpoint 4
>> control */
>> #define LOONGARCH_CSR_DB4ASID 0x333 /* data breakpoint 4
>> asid */
>> #define LOONGARCH_CSR_DB5ADDR 0x338 /* data breakpoint 5
>> address */
>> #define LOONGARCH_CSR_DB5MASK 0x339 /* data breakpoint 5
>> mask */
>> -#define LOONGARCH_CSR_DB5CTL 0x33a /* data breakpoint 5
>> control */
>> +#define LOONGARCH_CSR_DB5CTRL 0x33a /* data breakpoint 5
>> control */
>> #define LOONGARCH_CSR_DB5ASID 0x33b /* data breakpoint 5
>> asid */
>> #define LOONGARCH_CSR_DB6ADDR 0x340 /* data breakpoint 6
>> address */
>> #define LOONGARCH_CSR_DB6MASK 0x341 /* data breakpoint 6
>> mask */
>> -#define LOONGARCH_CSR_DB6CTL 0x342 /* data breakpoint 6
>> control */
>> +#define LOONGARCH_CSR_DB6CTRL 0x342 /* data breakpoint 6
>> control */
>> #define LOONGARCH_CSR_DB6ASID 0x343 /* data breakpoint 6
>> asid */
>> #define LOONGARCH_CSR_DB7ADDR 0x348 /* data breakpoint 7
>> address */
>> #define LOONGARCH_CSR_DB7MASK 0x349 /* data breakpoint 7
>> mask */
>> -#define LOONGARCH_CSR_DB7CTL 0x34a /* data breakpoint 7
>> control */
>> +#define LOONGARCH_CSR_DB7CTRL 0x34a /* data breakpoint 7
>> control */
>> #define LOONGARCH_CSR_DB7ASID 0x34b /* data breakpoint 7
>> asid */
>> #define LOONGARCH_CSR_FWPC 0x380 /* instruction breakpoint
>> config */
>> @@ -1013,42 +1013,42 @@ static __always_inline void iocsr_write64(u64
>> val, u32 reg)
>> #define LOONGARCH_CSR_IB0ADDR 0x390 /* inst breakpoint 0
>> address */
>> #define LOONGARCH_CSR_IB0MASK 0x391 /* inst breakpoint 0
>> mask */
>> -#define LOONGARCH_CSR_IB0CTL 0x392 /* inst breakpoint 0
>> control */
>> +#define LOONGARCH_CSR_IB0CTRL 0x392 /* inst breakpoint 0
>> control */
>> #define LOONGARCH_CSR_IB0ASID 0x393 /* inst breakpoint 0
>> asid */
>> #define LOONGARCH_CSR_IB1ADDR 0x398 /* inst breakpoint 1
>> address */
>> #define LOONGARCH_CSR_IB1MASK 0x399 /* inst breakpoint 1
>> mask */
>> -#define LOONGARCH_CSR_IB1CTL 0x39a /* inst breakpoint 1
>> control */
>> +#define LOONGARCH_CSR_IB1CTRL 0x39a /* inst breakpoint 1
>> control */
>> #define LOONGARCH_CSR_IB1ASID 0x39b /* inst breakpoint 1
>> asid */
>> #define LOONGARCH_CSR_IB2ADDR 0x3a0 /* inst breakpoint 2
>> address */
>> #define LOONGARCH_CSR_IB2MASK 0x3a1 /* inst breakpoint 2
>> mask */
>> -#define LOONGARCH_CSR_IB2CTL 0x3a2 /* inst breakpoint 2
>> control */
>> +#define LOONGARCH_CSR_IB2CTRL 0x3a2 /* inst breakpoint 2
>> control */
>> #define LOONGARCH_CSR_IB2ASID 0x3a3 /* inst breakpoint 2
>> asid */
>> #define LOONGARCH_CSR_IB3ADDR 0x3a8 /* inst breakpoint 3
>> address */
>> #define LOONGARCH_CSR_IB3MASK 0x3a9 /* breakpoint 3 mask */
>> -#define LOONGARCH_CSR_IB3CTL 0x3aa /* inst breakpoint 3
>> control */
>> +#define LOONGARCH_CSR_IB3CTRL 0x3aa /* inst breakpoint 3
>> control */
>> #define LOONGARCH_CSR_IB3ASID 0x3ab /* inst breakpoint 3
>> asid */
>> #define LOONGARCH_CSR_IB4ADDR 0x3b0 /* inst breakpoint 4
>> address */
>> #define LOONGARCH_CSR_IB4MASK 0x3b1 /* inst breakpoint 4
>> mask */
>> -#define LOONGARCH_CSR_IB4CTL 0x3b2 /* inst breakpoint 4
>> control */
>> +#define LOONGARCH_CSR_IB4CTRL 0x3b2 /* inst breakpoint 4
>> control */
>> #define LOONGARCH_CSR_IB4ASID 0x3b3 /* inst breakpoint 4
>> asid */
>> #define LOONGARCH_CSR_IB5ADDR 0x3b8 /* inst breakpoint 5
>> address */
>> #define LOONGARCH_CSR_IB5MASK 0x3b9 /* inst breakpoint 5
>> mask */
>> -#define LOONGARCH_CSR_IB5CTL 0x3ba /* inst breakpoint 5
>> control */
>> +#define LOONGARCH_CSR_IB5CTRL 0x3ba /* inst breakpoint 5
>> control */
>> #define LOONGARCH_CSR_IB5ASID 0x3bb /* inst breakpoint 5
>> asid */
>> #define LOONGARCH_CSR_IB6ADDR 0x3c0 /* inst breakpoint 6
>> address */
>> #define LOONGARCH_CSR_IB6MASK 0x3c1 /* inst breakpoint 6
>> mask */
>> -#define LOONGARCH_CSR_IB6CTL 0x3c2 /* inst breakpoint 6
>> control */
>> +#define LOONGARCH_CSR_IB6CTRL 0x3c2 /* inst breakpoint 6
>> control */
>> #define LOONGARCH_CSR_IB6ASID 0x3c3 /* inst breakpoint 6
>> asid */
>> #define LOONGARCH_CSR_IB7ADDR 0x3c8 /* inst breakpoint 7
>> address */
>> #define LOONGARCH_CSR_IB7MASK 0x3c9 /* inst breakpoint 7
>> mask */
>> -#define LOONGARCH_CSR_IB7CTL 0x3ca /* inst breakpoint 7
>> control */
>> +#define LOONGARCH_CSR_IB7CTRL 0x3ca /* inst breakpoint 7
>> control */
>> #define LOONGARCH_CSR_IB7ASID 0x3cb /* inst breakpoint 7
>> asid */
>> #define LOONGARCH_CSR_DEBUG 0x500 /* debug config */
>> diff --git a/arch/loongarch/include/asm/processor.h
>> b/arch/loongarch/include/asm/processor.h
>> index 7184f1dc61f2..f6ee920122d6 100644
>> --- a/arch/loongarch/include/asm/processor.h
>> +++ b/arch/loongarch/include/asm/processor.h
>> @@ -11,6 +11,7 @@
>> #include <asm/cpu.h>
>> #include <asm/cpu-info.h>
>> +#include <asm/hw_breakpoint.h>
>> #include <asm/loongarch.h>
>> #include <asm/vdso/processor.h>
>> #include <uapi/asm/ptrace.h>
>> @@ -131,6 +132,9 @@ struct thread_struct {
>> * they are conditionally copied at fork().
>> */
>> struct loongarch_fpu fpu FPU_ALIGN;
>> + /* Hardware breakpoints pinned to this task. */
>> + struct perf_event *hbp_break[LOONGARCH_MAX_BRP];
>> + struct perf_event *hbp_watch[LOONGARCH_MAX_WRP];
>> };
>> #define thread_saved_ra(tsk) (tsk->thread.sched_ra)
>> @@ -172,6 +176,8 @@ struct thread_struct {
>> .fcc = 0, \
>> .fpr = {{{0,},},}, \
>> }, \
>> + .hbp_break = {0}, \
>> + .hbp_watch = {0}, \
>> }
>> struct task_struct;
>> @@ -184,10 +190,6 @@ extern unsigned long
>> boot_option_idle_override;
>> */
>> extern void start_thread(struct pt_regs *regs, unsigned long pc,
>> unsigned long sp);
>> -static inline void flush_thread(void)
>> -{
>> -}
>> -
>> unsigned long __get_wchan(struct task_struct *p);
>> #define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
>> diff --git a/arch/loongarch/include/asm/switch_to.h
>> b/arch/loongarch/include/asm/switch_to.h
>> index 43a5ab162d38..24e3094bebab 100644
>> --- a/arch/loongarch/include/asm/switch_to.h
>> +++ b/arch/loongarch/include/asm/switch_to.h
>> @@ -34,6 +34,7 @@ extern asmlinkage struct task_struct
>> *__switch_to(struct task_struct *prev,
>> #define switch_to(prev, next, last) \
>> do { \
>> lose_fpu_inatomic(1, prev); \
>> + hw_breakpoint_thread_switch(next); \
>> (last) = __switch_to(prev, next, task_thread_info(next), \
>> __builtin_return_address(0), __builtin_frame_address(0)); \
>> } while (0)
>> diff --git a/arch/loongarch/kernel/Makefile
>> b/arch/loongarch/kernel/Makefile
>> index 7ca65195f7f8..b3aca7f2296e 100644
>> --- a/arch/loongarch/kernel/Makefile
>> +++ b/arch/loongarch/kernel/Makefile
>> @@ -46,6 +46,7 @@ obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
>> obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
>> obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
>> +obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
>> obj-$(CONFIG_KPROBES) += kprobes.o kprobes_trampoline.o
>> diff --git a/arch/loongarch/kernel/hw_breakpoint.c
>> b/arch/loongarch/kernel/hw_breakpoint.c
>> new file mode 100644
>> index 000000000000..16f38ceec321
>> --- /dev/null
>> +++ b/arch/loongarch/kernel/hw_breakpoint.c
>> @@ -0,0 +1,461 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>> + */
>> +#define pr_fmt(fmt) "hw-breakpoint: " fmt
>> +
>> +#include <linux/hw_breakpoint.h>
>> +#include <linux/kprobes.h>
>> +#include <linux/perf_event.h>
>> +
>> +#include <asm/hw_breakpoint.h>
>> +
>> +/* Breakpoint currently in use for each BRP. */
>> +static DEFINE_PER_CPU(struct perf_event *,
>> bp_on_reg[LOONGARCH_MAX_BRP]);
>> +
>> +/* Watchpoint currently in use for each WRP. */
>> +static DEFINE_PER_CPU(struct perf_event *,
>> wp_on_reg[LOONGARCH_MAX_WRP]);
>> +
>> +/* Number of BRP/WRP registers on this CPU. */
>> +static int core_num_brps;
>> +static int core_num_wrps;
>> +
>> +int hw_breakpoint_slots(int type)
>> +{
>> + /*
>> + * We can be called early, so don't rely on
>> + * our static variables being initialised.
>> + */
>> + switch (type) {
>> + case TYPE_INST:
>> + return get_num_brps();
>> + case TYPE_DATA:
>> + return get_num_wrps();
>> + default:
>> + pr_warn("unknown slot type: %d\n", type);
>> + return 0;
>> + }
>> +}
>> +
>> +#define READ_WB_REG_CASE(OFF, N, REG, T, VAL) \
>> + case (OFF + N): \
>> + LOONGARCH_CSR_READ(N, REG, T, VAL); \
>> + break
>> +
>> +#define WRITE_WB_REG_CASE(OFF, N, REG, T, VAL) \
>> + case (OFF + N): \
>> + LOONGARCH_CSR_WRITE(N, REG, T, VAL); \
>> + break
>> +
>> +#define GEN_READ_WB_REG_CASES(OFF, REG, T, VAL) \
>> + READ_WB_REG_CASE(OFF, 0, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 1, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 2, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 3, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 4, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 5, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 6, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 7, REG, T, VAL);
>> +
>> +#define GEN_WRITE_WB_REG_CASES(OFF, REG, T, VAL) \
>> + WRITE_WB_REG_CASE(OFF, 0, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 1, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 2, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 3, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 4, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 5, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 6, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 7, REG, T, VAL);
>> +
>> +static u64 read_wb_reg(int reg, int n, int t)
>> +{
>> + u64 val = 0;
>> +
>> + switch (reg + n) {
>> + GEN_READ_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
>> + GEN_READ_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
>> + GEN_READ_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
>> + GEN_READ_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
>> + default:
>> + pr_warn("attempt to read from unknown breakpoint register
>> %d\n", n);
>> + }
>> +
>> + return val;
>> +}
>> +NOKPROBE_SYMBOL(read_wb_reg);
>> +
>> +static void write_wb_reg(int reg, int n, int t, u64 val)
>> +{
>> + switch (reg + n) {
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
>> + default:
>> + pr_warn("attempt to write to unknown breakpoint register
>> %d\n", n);
>> + }
>> +}
>> +NOKPROBE_SYMBOL(write_wb_reg);
>> +
>> +enum hw_breakpoint_ops {
>> + HW_BREAKPOINT_INSTALL,
>> + HW_BREAKPOINT_UNINSTALL,
>> +};
>> +
>> +/**
>> + * hw_breakpoint_slot_setup - Find and setup a perf slot according to
>> + * operations
>> + *
>> + * @slots: pointer to array of slots
>> + * @max_slots: max number of slots
>> + * @bp: perf_event to setup
>> + * @ops: operation to be carried out on the slot
>> + *
>> + * Return:
>> + * slot index on success
>> + * -ENOSPC if no slot is available/matches
>> + * -EINVAL on wrong operations parameter
>> + */
>> +static int hw_breakpoint_slot_setup(struct perf_event **slots, int
>> max_slots,
>> + struct perf_event *bp,
>> + enum hw_breakpoint_ops ops)
>> +{
>> + int i;
>> + struct perf_event **slot;
>> +
>> + for (i = 0; i < max_slots; ++i) {
>> + slot = &slots[i];
>> + switch (ops) {
>> + case HW_BREAKPOINT_INSTALL:
>> + if (!*slot) {
>> + *slot = bp;
>> + return i;
>> + }
>> + break;
>> + case HW_BREAKPOINT_UNINSTALL:
>> + if (*slot == bp) {
>> + *slot = NULL;
>> + return i;
>> + }
>> + break;
>> + default:
>> + pr_warn_once("Unhandled hw breakpoint ops %d\n", ops);
>> + return -EINVAL;
>> + }
>> + }
>> + return -ENOSPC;
>> +}
>> +
>> +/*
>> + * Unregister breakpoints from this task and reset the pointers in
>> + * the thread_struct.
>> + */
>> +void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
>> +{
>> +}
>> +
>> +void ptrace_hw_copy_thread(struct task_struct *tsk)
>> +{
>> + memset(&tsk->thread.hbp_break, 0, sizeof(tsk->thread.hbp_break));
>> + memset(&tsk->thread.hbp_watch, 0, sizeof(tsk->thread.hbp_watch));
>> +}
>> +
>> +static int hw_breakpoint_control(struct perf_event *bp,
>> + enum hw_breakpoint_ops ops)
>> +{
>> + struct arch_hw_breakpoint *info = counter_arch_bp(bp);
>> + struct perf_event **slots;
>> + int i, max_slots, enable;
>> + u32 ctrl;
>> + struct pt_regs *regs = task_pt_regs(current);
>> +
>> + if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
>> + /* Breakpoint */
>> + slots = this_cpu_ptr(bp_on_reg);
>> + max_slots = core_num_brps;
>> + } else {
>> + /* Watchpoint */
>> + slots = this_cpu_ptr(wp_on_reg);
>> + max_slots = core_num_wrps;
>> + }
>> +
>> + i = hw_breakpoint_slot_setup(slots, max_slots, bp, ops);
>> +
>> + if (WARN_ONCE(i < 0, "Can't find any breakpoint slot"))
>> + return i;
>> +
>> + switch (ops) {
>> + case HW_BREAKPOINT_INSTALL:
>> + /* Set the FWPnCFG/MWPnCFG 1~3 register. */
>> + write_wb_reg(CSR_CFG_ADDR, i, 0, info->address);
>> + write_wb_reg(CSR_CFG_ADDR, i, 1, info->address);
>> + if (info->mask) {
>> + write_wb_reg(CSR_CFG_MASK, i, 0, info->mask);
>> + write_wb_reg(CSR_CFG_MASK, i, 1, info->mask);
>> + }
>> + write_wb_reg(CSR_CFG_ASID, i, 0, 0);
>> + write_wb_reg(CSR_CFG_ASID, i, 1, 0);
>> + ctrl = encode_ctrl_reg(info->ctrl);
>> + if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE)
>> + write_wb_reg(CSR_CFG_CTRL, i, 0, ctrl | 0x1e);
>> + else
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl | 0x1e | 1 << 8 |
>> 1 << 9);
>> +
>> + enable = csr_read64(LOONGARCH_CSR_CRMD);
>> + csr_write64(1 << 9 | enable, LOONGARCH_CSR_CRMD);
>> + break;
>> + case HW_BREAKPOINT_UNINSTALL:
>> + /* Reset the FWPnCFG/MWPnCFG 1~3 register. */
>> + write_wb_reg(CSR_CFG_ADDR, i, 0, 0);
>> + write_wb_reg(CSR_CFG_ADDR, i, 1, 0);
>> + write_wb_reg(CSR_CFG_MASK, i, 0, 0);
>> + write_wb_reg(CSR_CFG_MASK, i, 1, 0);
>> + write_wb_reg(CSR_CFG_CTRL, i, 0, 0);
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, 0);
>> + write_wb_reg(CSR_CFG_ASID, i, 0, 0);
>> + write_wb_reg(CSR_CFG_ASID, i, 1, 0);
>> + break;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +/*
>> + * Install a perf counter breakpoint.
>> + */
>> +int arch_install_hw_breakpoint(struct perf_event *bp)
>> +{
>> + return hw_breakpoint_control(bp, HW_BREAKPOINT_INSTALL);
>> +}
>> +
>> +void arch_uninstall_hw_breakpoint(struct perf_event *bp)
>> +{
>> + hw_breakpoint_control(bp, HW_BREAKPOINT_UNINSTALL);
>> +}
>> +
>> +static int get_hbp_len(u8 hbp_len)
> An array for simplify.
>> +{
>> + unsigned int len_in_bytes = 0;
>> +
>> + switch (hbp_len) {
>> + case LOONGARCH_BREAKPOINT_LEN_1:
>> + len_in_bytes = 1;
>> + break;
>> + case LOONGARCH_BREAKPOINT_LEN_2:
>> + len_in_bytes = 2;
>> + break;
>> + case LOONGARCH_BREAKPOINT_LEN_4:
>> + len_in_bytes = 4;
>> + break;
>> + case LOONGARCH_BREAKPOINT_LEN_8:
>> + len_in_bytes = 8;
>> + break;
>> + }
>> +
>> + return len_in_bytes;
>> +}
>> +
>> +/*
>> + * Check whether bp virtual address is in kernel space.
>> + */
>> +int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw)
>> +{
>> + unsigned int len;
>> + unsigned long va;
>> +
>> + va = hw->address;
>> + len = get_hbp_len(hw->ctrl.len);
>> +
>> + return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
>> +}
>> +
>> +/*
>> + * Construct an arch_hw_breakpoint from a perf_event.
>> + */
>> +static int arch_build_bp_info(struct perf_event *bp,
>> + const struct perf_event_attr *attr,
>> + struct arch_hw_breakpoint *hw)
>> +{
>> + /* Type */
>> + switch (attr->bp_type) {
>> + case HW_BREAKPOINT_X:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_EXECUTE;
>> + break;
>> + case HW_BREAKPOINT_R:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD;
>> + break;
>> + case HW_BREAKPOINT_W:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_STORE;
>> + break;
>> + case HW_BREAKPOINT_RW:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD |
>> LOONGARCH_BREAKPOINT_STORE;
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + /* Len */
>> + switch (attr->bp_len) {
>> + case HW_BREAKPOINT_LEN_1:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_1;
>> + break;
>> + case HW_BREAKPOINT_LEN_2:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_2;
>> + break;
>> + case HW_BREAKPOINT_LEN_4:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_4;
>> + break;
>> + case HW_BREAKPOINT_LEN_8:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_8;
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + /* Address */
>> + hw->address = attr->bp_addr;
>> +
>> + return 0;
>> +}
>> +
>> +/*
>> + * Validate the arch-specific HW Breakpoint register settings.
>> + */
>> +int hw_breakpoint_arch_parse(struct perf_event *bp,
>> + const struct perf_event_attr *attr,
>> + struct arch_hw_breakpoint *hw)
>> +{
>> + int ret;
>> + u64 alignment_mask, offset;
>> +
>> + /* Build the arch_hw_breakpoint. */
>> + ret = arch_build_bp_info(bp, attr, hw);
>> + if (ret)
>> + return ret;
>> +
>> + if (hw->ctrl.type != LOONGARCH_BREAKPOINT_EXECUTE)
>> + alignment_mask = 0x7;
>> + offset = hw->address & alignment_mask;
>> +
>> + hw->address &= ~alignment_mask;
>> + hw->ctrl.len <<= offset;
>> +
>> + return 0;
>> +}
>> +
>> +#define PRMD_WE (1UL<<3) /*prmd watch enable, restore to crmd when
>> eret*/
>> +static void update_bp_registers(struct pt_regs *regs, int enable)
> Use macro in this function for ...
>> +{
>> + int i, max_slots;
>> + u32 ctrl;
>> + struct perf_event **slots;
>> +
>> + if (csr_read64(LOONGARCH_CSR_FWPS) & 0xff) {
>> + slots = this_cpu_ptr(bp_on_reg);
>> + max_slots = core_num_brps;
>> +
>> + } else if (csr_read64(LOONGARCH_CSR_MWPS) & 0xff) {
>> + slots = this_cpu_ptr(wp_on_reg);
>> + max_slots = core_num_wrps;
>> + } else {
>> + return;
>> + }
>> +
>> + for (i = 0; i < max_slots; ++i) {
>> + if (!slots[i])
>> + continue;
>> +
>> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
>> + if (enable) {
>> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
>> + ctrl |= 0x1 << 8;
>> + ctrl |= 0x1 << 9;
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
>> + regs->csr_prmd |= PRMD_WE;
>> + } else {
>> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
>> + ctrl &= ~0x1 << 8;
>> + ctrl &= ~0x1 << 9;
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
>> + regs->csr_prmd &= ~PRMD_WE;
>> + }
>> + }
>> +}
>> +NOKPROBE_SYMBOL(update_bp_registers);
>> +
>> +/*
>> + * Debug exception handlers.
>> + */
>> +int breakpoint_handler(struct pt_regs *regs)
>> +{
>> + int i;
>> + u64 addr;
>> + struct perf_event *bp, **slots;
>> +
>> + slots = this_cpu_ptr(bp_on_reg);
>> +
>> + for (i = 0; i < core_num_brps; ++i) {
>> + bp = slots[i];
>> + if (bp == NULL)
>> + continue;
>> + perf_bp_event(bp, regs);
>> + }
>> + update_bp_registers(regs, 0);
>> +
>> + return 0;
>> +}
>> +NOKPROBE_SYMBOL(breakpoint_handler);
>> +
>> +int watchpoint_handler(struct pt_regs *regs)
>> +{
>> + int i;
>> + struct perf_event *wp, **slots;
>> +
>> + slots = this_cpu_ptr(wp_on_reg);
>> +
>> + for (i = 0; i < core_num_wrps; ++i) {
>> + wp = slots[i];
>> + if (wp == NULL)
>> + continue;
>> + perf_bp_event(wp, regs);
>> + }
>> + update_bp_registers(regs, 0);
>> +
>> + return 0;
>> +}
>> +NOKPROBE_SYMBOL(watchpoint_handler);
>> +
>> +/*
>> + * One-time initialisation.
>> + */
>> +static int __init arch_hw_breakpoint_init(void)
>> +{
>> + core_num_brps = get_num_brps();
>> + core_num_wrps = get_num_wrps();
>> +
>> + pr_info("found %d breakpoint and %d watchpoint registers.\n",
>> + core_num_brps, core_num_wrps);
>> + return 0;
>> +}
>> +arch_initcall(arch_hw_breakpoint_init);
>> +
>> +void hw_breakpoint_thread_switch(struct task_struct *next)
>> +{
>> + struct pt_regs *regs = task_pt_regs(next);
>> +
>> + /* Update breakpoints/watchpoints. */
>> + update_bp_registers(regs, 1);
>> +}
>> +
>> +void hw_breakpoint_pmu_read(struct perf_event *bp)
>> +{
>> +}
>> +
>> +/*
>> + * Dummy function to register with die_notifier.
>> + */
>> +int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
>> + unsigned long val, void *data)
>> +{
>> + return NOTIFY_DONE;
>> +}
>> diff --git a/arch/loongarch/kernel/process.c
>> b/arch/loongarch/kernel/process.c
>> index 27c8cacbce01..f78574562329 100644
>> --- a/arch/loongarch/kernel/process.c
>> +++ b/arch/loongarch/kernel/process.c
>> @@ -37,6 +37,7 @@
>> #include <asm/cpu.h>
>> #include <asm/elf.h>
>> #include <asm/fpu.h>
>> +#include <linux/hw_breakpoint.h>
> ...
>> #include <asm/io.h>
>> #include <asm/irq.h>
>> #include <asm/irq_regs.h>
>> @@ -100,6 +101,11 @@ void exit_thread(struct task_struct *tsk)
>> {
>> }
>> +void flush_thread(void)
>> +{
>> + flush_ptrace_hw_breakpoint(current);
>> +}
>> +
>> int arch_dup_task_struct(struct task_struct *dst, struct task_struct
>> *src)
>> {
>> /*
>> @@ -186,6 +192,8 @@ int copy_thread(struct task_struct *p, const
>> struct kernel_clone_args *args)
>> if (clone_flags & CLONE_SETTLS)
>> childregs->regs[2] = tls;
>> + ptrace_hw_copy_thread(p);
>> +
>> out:
>> clear_tsk_thread_flag(p, TIF_USEDFPU);
>> clear_tsk_thread_flag(p, TIF_USEDSIMD);
>> diff --git a/arch/loongarch/kernel/traps.c
>> b/arch/loongarch/kernel/traps.c
>> index 4d9f77565703..d59cf93a4c31 100644
>> --- a/arch/loongarch/kernel/traps.c
>> +++ b/arch/loongarch/kernel/traps.c
>> @@ -45,6 +45,7 @@
>> #include <asm/tlb.h>
>> #include <asm/types.h>
>> #include <asm/unwind.h>
>> +#include <asm/hw_breakpoint.h>
>> #include "access-helper.h"
>> @@ -514,7 +515,19 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs)
>> asmlinkage void noinstr do_watch(struct pt_regs *regs)
>> {
>> - pr_warn("Hardware watch point handler not implemented!\n");
>> + enum ctx_state prev_state;
>> +
>> + prev_state = exception_enter();
>> +
>> +#ifdef CONFIG_HAVE_HW_BREAKPOINT
>> + if (breakpoint_handler(regs))
>> + return;
>> + if (watchpoint_handler(regs))
>> + return;
>> +#endif
>> + force_sig(SIGTRAP);
>> + exception_exit(prev_state);
>> + return;
>> }
>> asmlinkage void noinstr do_ri(struct pt_regs *regs)
Thanks for your suggestions, they are useful, I'll make some more
details to improve.
Thanks,
-Qing
>
> Thanks,
>
> jinyang
Hi, Qing
On 12/13/2022 05:10 PM, qing zhang wrote:
> From: Qing Zhang <[email protected]>
>
> Use perf framework to manage hardware instruction and data breakpoints.
> LoongArch defines hardware watchpoint functions for instruction fetch
> and load/store operations, after the software configures hardware watchpoints
> for instruction fetch and load/store operations. The processor hardware will
> monitor the access address of the instruction fetch and load/store operation,
> and will trigger the exception of the watchpoint when it meets the conditions
> set by the watchpoint.
>
> The hardware monitoring points for instruction fetching and load/store operations
> each have a register for the overall configuration of all monitoring points,
> a register for recording the status of all monitoring points, and four registers
> required for configuration of each watchpoint individually.
>
> Watchpoint related control status register chapters:
> https://github.com/loongson/LoongArch-Documentation/releases/download/2022.08.12/
> LoongArch-Vol1-v1.02-CN.pdf
>
> Initial version has the following limitations:
> - userspace debug is not yet enabled: work on ptrace/gdb is in progress
> - no support for virtualization
>
> Despite missing userspace debug, initial implementation can be tested: e.g.
> see samples/hw_breakpoint and register_wide_hw_breakpoint.
Perhaps the existing test phenomenon should be exported to give an
intuitive sense of this feature.
Thanks,
Youling.
>
> TODO:
> - Add Kernel tools that use hardware breakpoints: Kgdb, Ptrace
> - Add hardware breakpoints/watchpoints for gdb
>
> Signed-off-by: Qing Zhang <[email protected]>
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index 12571eedc488..69199812fe74 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -99,6 +99,7 @@ config LOONGARCH
> select HAVE_FUNCTION_GRAPH_TRACER
> select HAVE_FUNCTION_TRACER
> select HAVE_GENERIC_VDSO
> + select HAVE_HW_BREAKPOINT if PERF_EVENTS
> select HAVE_IOREMAP_PROT
> select HAVE_IRQ_EXIT_ON_IRQ_STACK
> select HAVE_IRQ_TIME_ACCOUNTING
> diff --git a/arch/loongarch/include/asm/hw_breakpoint.h b/arch/loongarch/include/asm/hw_breakpoint.h
> new file mode 100644
> index 000000000000..a57caf117960
> --- /dev/null
> +++ b/arch/loongarch/include/asm/hw_breakpoint.h
> @@ -0,0 +1,140 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +#ifndef __ASM_HW_BREAKPOINT_H
> +#define __ASM_HW_BREAKPOINT_H
> +
> +#include <asm/loongarch.h>
> +
> +#ifdef __KERNEL__
> +
> +/* Breakpoint */
> +#define LOONGARCH_BREAKPOINT_EXECUTE (0 << 0)
> +
> +/* Watchpoints */
> +#define LOONGARCH_BREAKPOINT_LOAD (1 << 0)
> +#define LOONGARCH_BREAKPOINT_STORE (1 << 1)
> +
> +struct arch_hw_breakpoint_ctrl {
> + u32 __reserved : 28,
> + type : 2,
> + len : 2;
> +};
> +
> +struct arch_hw_breakpoint {
> + u64 address;
> + u64 mask;
> + struct arch_hw_breakpoint_ctrl ctrl;
> +};
> +
> +/* Lengths */
> +#define LOONGARCH_BREAKPOINT_LEN_1 0b11
> +#define LOONGARCH_BREAKPOINT_LEN_2 0b10
> +#define LOONGARCH_BREAKPOINT_LEN_4 0b01
> +#define LOONGARCH_BREAKPOINT_LEN_8 0b00
> +
> +/*
> + * Limits.
> + * Changing these will require modifications to the register accessors.
> + */
> +#define LOONGARCH_MAX_BRP 8
> +#define LOONGARCH_MAX_WRP 8
> +
> +/* Virtual debug register bases. */
> +#define CSR_CFG_ADDR 0
> +#define CSR_CFG_MASK (CSR_CFG_ADDR + LOONGARCH_MAX_BRP)
> +#define CSR_CFG_CTRL (CSR_CFG_MASK + LOONGARCH_MAX_BRP)
> +#define CSR_CFG_ASID (CSR_CFG_CTRL + LOONGARCH_MAX_WRP)
> +
> +/* Debug register names. */
> +#define LOONGARCH_CSR_NAME_ADDR ADDR
> +#define LOONGARCH_CSR_NAME_MASK MASK
> +#define LOONGARCH_CSR_NAME_CTRL CTRL
> +#define LOONGARCH_CSR_NAME_ASID ASID
> +
> +/* Accessor macros for the debug registers. */
> +#define LOONGARCH_CSR_READ(N, REG, T, VAL) \
> +do { \
> + if (T == 0) \
> + VAL = csr_read64(LOONGARCH_CSR_##IB##N##REG); \
> + else \
> + VAL = csr_read64(LOONGARCH_CSR_##DB##N##REG); \
> +} while (0)
> +
> +#define LOONGARCH_CSR_WRITE(N, REG, T, VAL) \
> +do { \
> + if (T == 0) \
> + csr_write64(VAL, LOONGARCH_CSR_##IB##N##REG); \
> + else \
> + csr_write64(VAL, LOONGARCH_CSR_##DB##N##REG); \
> +} while (0)
> +
> +static inline u32 encode_ctrl_reg(struct arch_hw_breakpoint_ctrl ctrl)
> +{
> + u32 val = (ctrl.len << 2) | ctrl.type;
> +
> + return val;
> +}
> +
> +static inline void decode_ctrl_reg(u32 reg, struct arch_hw_breakpoint_ctrl *ctrl)
> +{
> + ctrl->type = reg & 0x3;
> + reg >>= 2;
> + ctrl->len = reg & 0x3;
> +}
> +
> +struct task_struct;
> +struct notifier_block;
> +struct perf_event_attr;
> +struct perf_event;
> +
> +extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
> + int *gen_len, int *gen_type, int *offset);
> +extern int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw);
> +extern int hw_breakpoint_arch_parse(struct perf_event *bp,
> + const struct perf_event_attr *attr,
> + struct arch_hw_breakpoint *hw);
> +extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
> + unsigned long val, void *data);
> +
> +extern int arch_install_hw_breakpoint(struct perf_event *bp);
> +extern void arch_uninstall_hw_breakpoint(struct perf_event *bp);
> +extern void hw_breakpoint_pmu_read(struct perf_event *bp);
> +extern int hw_breakpoint_slots(int type);
> +
> +int breakpoint_handler(struct pt_regs *regs);
> +int watchpoint_handler(struct pt_regs *regs);
> +
> +#ifdef CONFIG_HAVE_HW_BREAKPOINT
> +extern void hw_breakpoint_thread_switch(struct task_struct *next);
> +extern void ptrace_hw_copy_thread(struct task_struct *task);
> +#else
> +static inline void hw_breakpoint_thread_switch(struct task_struct *next)
> +{
> +}
> +static inline void ptrace_hw_copy_thread(struct task_struct *task)
> +{
> +}
> +#endif
> +
> +/* Determine number of BRP registers available. */
> +static inline int get_num_brps(void)
> +{
> + unsigned int ibcn;
> +
> + ibcn = csr_read64(LOONGARCH_CSR_FWPC) & 0x3f;
> + return ibcn;
> +}
> +
> +/* Determine number of WRP registers available. */
> +static inline int get_num_wrps(void)
> +{
> + unsigned int dbcn;
> +
> + dbcn = csr_read64(LOONGARCH_CSR_MWPC) & 0x3f;
> + return dbcn;
> +}
> +
> +#endif /* __KERNEL__ */
> +#endif /* __ASM_BREAKPOINT_H */
> diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
> index 7f8d57a61c8b..e9aed583a064 100644
> --- a/arch/loongarch/include/asm/loongarch.h
> +++ b/arch/loongarch/include/asm/loongarch.h
> @@ -970,42 +970,42 @@ static __always_inline void iocsr_write64(u64 val, u32 reg)
>
> #define LOONGARCH_CSR_DB0ADDR 0x310 /* data breakpoint 0 address */
> #define LOONGARCH_CSR_DB0MASK 0x311 /* data breakpoint 0 mask */
> -#define LOONGARCH_CSR_DB0CTL 0x312 /* data breakpoint 0 control */
> +#define LOONGARCH_CSR_DB0CTRL 0x312 /* data breakpoint 0 control */
> #define LOONGARCH_CSR_DB0ASID 0x313 /* data breakpoint 0 asid */
>
> #define LOONGARCH_CSR_DB1ADDR 0x318 /* data breakpoint 1 address */
> #define LOONGARCH_CSR_DB1MASK 0x319 /* data breakpoint 1 mask */
> -#define LOONGARCH_CSR_DB1CTL 0x31a /* data breakpoint 1 control */
> +#define LOONGARCH_CSR_DB1CTRL 0x31a /* data breakpoint 1 control */
> #define LOONGARCH_CSR_DB1ASID 0x31b /* data breakpoint 1 asid */
>
> #define LOONGARCH_CSR_DB2ADDR 0x320 /* data breakpoint 2 address */
> #define LOONGARCH_CSR_DB2MASK 0x321 /* data breakpoint 2 mask */
> -#define LOONGARCH_CSR_DB2CTL 0x322 /* data breakpoint 2 control */
> +#define LOONGARCH_CSR_DB2CTRL 0x322 /* data breakpoint 2 control */
> #define LOONGARCH_CSR_DB2ASID 0x323 /* data breakpoint 2 asid */
>
> #define LOONGARCH_CSR_DB3ADDR 0x328 /* data breakpoint 3 address */
> #define LOONGARCH_CSR_DB3MASK 0x329 /* data breakpoint 3 mask */
> -#define LOONGARCH_CSR_DB3CTL 0x32a /* data breakpoint 3 control */
> +#define LOONGARCH_CSR_DB3CTRL 0x32a /* data breakpoint 3 control */
> #define LOONGARCH_CSR_DB3ASID 0x32b /* data breakpoint 3 asid */
>
> #define LOONGARCH_CSR_DB4ADDR 0x330 /* data breakpoint 4 address */
> #define LOONGARCH_CSR_DB4MASK 0x331 /* data breakpoint 4 maks */
> -#define LOONGARCH_CSR_DB4CTL 0x332 /* data breakpoint 4 control */
> +#define LOONGARCH_CSR_DB4CTRL 0x332 /* data breakpoint 4 control */
> #define LOONGARCH_CSR_DB4ASID 0x333 /* data breakpoint 4 asid */
>
> #define LOONGARCH_CSR_DB5ADDR 0x338 /* data breakpoint 5 address */
> #define LOONGARCH_CSR_DB5MASK 0x339 /* data breakpoint 5 mask */
> -#define LOONGARCH_CSR_DB5CTL 0x33a /* data breakpoint 5 control */
> +#define LOONGARCH_CSR_DB5CTRL 0x33a /* data breakpoint 5 control */
> #define LOONGARCH_CSR_DB5ASID 0x33b /* data breakpoint 5 asid */
>
> #define LOONGARCH_CSR_DB6ADDR 0x340 /* data breakpoint 6 address */
> #define LOONGARCH_CSR_DB6MASK 0x341 /* data breakpoint 6 mask */
> -#define LOONGARCH_CSR_DB6CTL 0x342 /* data breakpoint 6 control */
> +#define LOONGARCH_CSR_DB6CTRL 0x342 /* data breakpoint 6 control */
> #define LOONGARCH_CSR_DB6ASID 0x343 /* data breakpoint 6 asid */
>
> #define LOONGARCH_CSR_DB7ADDR 0x348 /* data breakpoint 7 address */
> #define LOONGARCH_CSR_DB7MASK 0x349 /* data breakpoint 7 mask */
> -#define LOONGARCH_CSR_DB7CTL 0x34a /* data breakpoint 7 control */
> +#define LOONGARCH_CSR_DB7CTRL 0x34a /* data breakpoint 7 control */
> #define LOONGARCH_CSR_DB7ASID 0x34b /* data breakpoint 7 asid */
>
> #define LOONGARCH_CSR_FWPC 0x380 /* instruction breakpoint config */
> @@ -1013,42 +1013,42 @@ static __always_inline void iocsr_write64(u64 val, u32 reg)
>
> #define LOONGARCH_CSR_IB0ADDR 0x390 /* inst breakpoint 0 address */
> #define LOONGARCH_CSR_IB0MASK 0x391 /* inst breakpoint 0 mask */
> -#define LOONGARCH_CSR_IB0CTL 0x392 /* inst breakpoint 0 control */
> +#define LOONGARCH_CSR_IB0CTRL 0x392 /* inst breakpoint 0 control */
> #define LOONGARCH_CSR_IB0ASID 0x393 /* inst breakpoint 0 asid */
>
> #define LOONGARCH_CSR_IB1ADDR 0x398 /* inst breakpoint 1 address */
> #define LOONGARCH_CSR_IB1MASK 0x399 /* inst breakpoint 1 mask */
> -#define LOONGARCH_CSR_IB1CTL 0x39a /* inst breakpoint 1 control */
> +#define LOONGARCH_CSR_IB1CTRL 0x39a /* inst breakpoint 1 control */
> #define LOONGARCH_CSR_IB1ASID 0x39b /* inst breakpoint 1 asid */
>
> #define LOONGARCH_CSR_IB2ADDR 0x3a0 /* inst breakpoint 2 address */
> #define LOONGARCH_CSR_IB2MASK 0x3a1 /* inst breakpoint 2 mask */
> -#define LOONGARCH_CSR_IB2CTL 0x3a2 /* inst breakpoint 2 control */
> +#define LOONGARCH_CSR_IB2CTRL 0x3a2 /* inst breakpoint 2 control */
> #define LOONGARCH_CSR_IB2ASID 0x3a3 /* inst breakpoint 2 asid */
>
> #define LOONGARCH_CSR_IB3ADDR 0x3a8 /* inst breakpoint 3 address */
> #define LOONGARCH_CSR_IB3MASK 0x3a9 /* breakpoint 3 mask */
> -#define LOONGARCH_CSR_IB3CTL 0x3aa /* inst breakpoint 3 control */
> +#define LOONGARCH_CSR_IB3CTRL 0x3aa /* inst breakpoint 3 control */
> #define LOONGARCH_CSR_IB3ASID 0x3ab /* inst breakpoint 3 asid */
>
> #define LOONGARCH_CSR_IB4ADDR 0x3b0 /* inst breakpoint 4 address */
> #define LOONGARCH_CSR_IB4MASK 0x3b1 /* inst breakpoint 4 mask */
> -#define LOONGARCH_CSR_IB4CTL 0x3b2 /* inst breakpoint 4 control */
> +#define LOONGARCH_CSR_IB4CTRL 0x3b2 /* inst breakpoint 4 control */
> #define LOONGARCH_CSR_IB4ASID 0x3b3 /* inst breakpoint 4 asid */
>
> #define LOONGARCH_CSR_IB5ADDR 0x3b8 /* inst breakpoint 5 address */
> #define LOONGARCH_CSR_IB5MASK 0x3b9 /* inst breakpoint 5 mask */
> -#define LOONGARCH_CSR_IB5CTL 0x3ba /* inst breakpoint 5 control */
> +#define LOONGARCH_CSR_IB5CTRL 0x3ba /* inst breakpoint 5 control */
> #define LOONGARCH_CSR_IB5ASID 0x3bb /* inst breakpoint 5 asid */
>
> #define LOONGARCH_CSR_IB6ADDR 0x3c0 /* inst breakpoint 6 address */
> #define LOONGARCH_CSR_IB6MASK 0x3c1 /* inst breakpoint 6 mask */
> -#define LOONGARCH_CSR_IB6CTL 0x3c2 /* inst breakpoint 6 control */
> +#define LOONGARCH_CSR_IB6CTRL 0x3c2 /* inst breakpoint 6 control */
> #define LOONGARCH_CSR_IB6ASID 0x3c3 /* inst breakpoint 6 asid */
>
> #define LOONGARCH_CSR_IB7ADDR 0x3c8 /* inst breakpoint 7 address */
> #define LOONGARCH_CSR_IB7MASK 0x3c9 /* inst breakpoint 7 mask */
> -#define LOONGARCH_CSR_IB7CTL 0x3ca /* inst breakpoint 7 control */
> +#define LOONGARCH_CSR_IB7CTRL 0x3ca /* inst breakpoint 7 control */
> #define LOONGARCH_CSR_IB7ASID 0x3cb /* inst breakpoint 7 asid */
>
> #define LOONGARCH_CSR_DEBUG 0x500 /* debug config */
> diff --git a/arch/loongarch/include/asm/processor.h b/arch/loongarch/include/asm/processor.h
> index 7184f1dc61f2..f6ee920122d6 100644
> --- a/arch/loongarch/include/asm/processor.h
> +++ b/arch/loongarch/include/asm/processor.h
> @@ -11,6 +11,7 @@
>
> #include <asm/cpu.h>
> #include <asm/cpu-info.h>
> +#include <asm/hw_breakpoint.h>
> #include <asm/loongarch.h>
> #include <asm/vdso/processor.h>
> #include <uapi/asm/ptrace.h>
> @@ -131,6 +132,9 @@ struct thread_struct {
> * they are conditionally copied at fork().
> */
> struct loongarch_fpu fpu FPU_ALIGN;
> + /* Hardware breakpoints pinned to this task. */
> + struct perf_event *hbp_break[LOONGARCH_MAX_BRP];
> + struct perf_event *hbp_watch[LOONGARCH_MAX_WRP];
> };
>
> #define thread_saved_ra(tsk) (tsk->thread.sched_ra)
> @@ -172,6 +176,8 @@ struct thread_struct {
> .fcc = 0, \
> .fpr = {{{0,},},}, \
> }, \
> + .hbp_break = {0}, \
> + .hbp_watch = {0}, \
> }
>
> struct task_struct;
> @@ -184,10 +190,6 @@ extern unsigned long boot_option_idle_override;
> */
> extern void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp);
>
> -static inline void flush_thread(void)
> -{
> -}
> -
> unsigned long __get_wchan(struct task_struct *p);
>
> #define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
> diff --git a/arch/loongarch/include/asm/switch_to.h b/arch/loongarch/include/asm/switch_to.h
> index 43a5ab162d38..24e3094bebab 100644
> --- a/arch/loongarch/include/asm/switch_to.h
> +++ b/arch/loongarch/include/asm/switch_to.h
> @@ -34,6 +34,7 @@ extern asmlinkage struct task_struct *__switch_to(struct task_struct *prev,
> #define switch_to(prev, next, last) \
> do { \
> lose_fpu_inatomic(1, prev); \
> + hw_breakpoint_thread_switch(next); \
> (last) = __switch_to(prev, next, task_thread_info(next), \
> __builtin_return_address(0), __builtin_frame_address(0)); \
> } while (0)
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> index 7ca65195f7f8..b3aca7f2296e 100644
> --- a/arch/loongarch/kernel/Makefile
> +++ b/arch/loongarch/kernel/Makefile
> @@ -46,6 +46,7 @@ obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
> obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
>
> obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
> +obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
>
> obj-$(CONFIG_KPROBES) += kprobes.o kprobes_trampoline.o
>
> diff --git a/arch/loongarch/kernel/hw_breakpoint.c b/arch/loongarch/kernel/hw_breakpoint.c
> new file mode 100644
> index 000000000000..16f38ceec321
> --- /dev/null
> +++ b/arch/loongarch/kernel/hw_breakpoint.c
> @@ -0,0 +1,461 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +#define pr_fmt(fmt) "hw-breakpoint: " fmt
> +
> +#include <linux/hw_breakpoint.h>
> +#include <linux/kprobes.h>
> +#include <linux/perf_event.h>
> +
> +#include <asm/hw_breakpoint.h>
> +
> +/* Breakpoint currently in use for each BRP. */
> +static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[LOONGARCH_MAX_BRP]);
> +
> +/* Watchpoint currently in use for each WRP. */
> +static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[LOONGARCH_MAX_WRP]);
> +
> +/* Number of BRP/WRP registers on this CPU. */
> +static int core_num_brps;
> +static int core_num_wrps;
> +
> +int hw_breakpoint_slots(int type)
> +{
> + /*
> + * We can be called early, so don't rely on
> + * our static variables being initialised.
> + */
> + switch (type) {
> + case TYPE_INST:
> + return get_num_brps();
> + case TYPE_DATA:
> + return get_num_wrps();
> + default:
> + pr_warn("unknown slot type: %d\n", type);
> + return 0;
> + }
> +}
> +
> +#define READ_WB_REG_CASE(OFF, N, REG, T, VAL) \
> + case (OFF + N): \
> + LOONGARCH_CSR_READ(N, REG, T, VAL); \
> + break
> +
> +#define WRITE_WB_REG_CASE(OFF, N, REG, T, VAL) \
> + case (OFF + N): \
> + LOONGARCH_CSR_WRITE(N, REG, T, VAL); \
> + break
> +
> +#define GEN_READ_WB_REG_CASES(OFF, REG, T, VAL) \
> + READ_WB_REG_CASE(OFF, 0, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 1, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 2, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 3, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 4, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 5, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 6, REG, T, VAL); \
> + READ_WB_REG_CASE(OFF, 7, REG, T, VAL);
> +
> +#define GEN_WRITE_WB_REG_CASES(OFF, REG, T, VAL) \
> + WRITE_WB_REG_CASE(OFF, 0, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 1, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 2, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 3, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 4, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 5, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 6, REG, T, VAL); \
> + WRITE_WB_REG_CASE(OFF, 7, REG, T, VAL);
> +
> +static u64 read_wb_reg(int reg, int n, int t)
> +{
> + u64 val = 0;
> +
> + switch (reg + n) {
> + GEN_READ_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
> + GEN_READ_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
> + GEN_READ_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
> + GEN_READ_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
> + default:
> + pr_warn("attempt to read from unknown breakpoint register %d\n", n);
> + }
> +
> + return val;
> +}
> +NOKPROBE_SYMBOL(read_wb_reg);
> +
> +static void write_wb_reg(int reg, int n, int t, u64 val)
> +{
> + switch (reg + n) {
> + GEN_WRITE_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
> + GEN_WRITE_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
> + GEN_WRITE_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
> + GEN_WRITE_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
> + default:
> + pr_warn("attempt to write to unknown breakpoint register %d\n", n);
> + }
> +}
> +NOKPROBE_SYMBOL(write_wb_reg);
> +
> +enum hw_breakpoint_ops {
> + HW_BREAKPOINT_INSTALL,
> + HW_BREAKPOINT_UNINSTALL,
> +};
> +
> +/**
> + * hw_breakpoint_slot_setup - Find and setup a perf slot according to
> + * operations
> + *
> + * @slots: pointer to array of slots
> + * @max_slots: max number of slots
> + * @bp: perf_event to setup
> + * @ops: operation to be carried out on the slot
> + *
> + * Return:
> + * slot index on success
> + * -ENOSPC if no slot is available/matches
> + * -EINVAL on wrong operations parameter
> + */
> +static int hw_breakpoint_slot_setup(struct perf_event **slots, int max_slots,
> + struct perf_event *bp,
> + enum hw_breakpoint_ops ops)
> +{
> + int i;
> + struct perf_event **slot;
> +
> + for (i = 0; i < max_slots; ++i) {
> + slot = &slots[i];
> + switch (ops) {
> + case HW_BREAKPOINT_INSTALL:
> + if (!*slot) {
> + *slot = bp;
> + return i;
> + }
> + break;
> + case HW_BREAKPOINT_UNINSTALL:
> + if (*slot == bp) {
> + *slot = NULL;
> + return i;
> + }
> + break;
> + default:
> + pr_warn_once("Unhandled hw breakpoint ops %d\n", ops);
> + return -EINVAL;
> + }
> + }
> + return -ENOSPC;
> +}
> +
> +/*
> + * Unregister breakpoints from this task and reset the pointers in
> + * the thread_struct.
> + */
> +void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
> +{
> +}
> +
> +void ptrace_hw_copy_thread(struct task_struct *tsk)
> +{
> + memset(&tsk->thread.hbp_break, 0, sizeof(tsk->thread.hbp_break));
> + memset(&tsk->thread.hbp_watch, 0, sizeof(tsk->thread.hbp_watch));
> +}
> +
> +static int hw_breakpoint_control(struct perf_event *bp,
> + enum hw_breakpoint_ops ops)
> +{
> + struct arch_hw_breakpoint *info = counter_arch_bp(bp);
> + struct perf_event **slots;
> + int i, max_slots, enable;
> + u32 ctrl;
> + struct pt_regs *regs = task_pt_regs(current);
> +
> + if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
> + /* Breakpoint */
> + slots = this_cpu_ptr(bp_on_reg);
> + max_slots = core_num_brps;
> + } else {
> + /* Watchpoint */
> + slots = this_cpu_ptr(wp_on_reg);
> + max_slots = core_num_wrps;
> + }
> +
> + i = hw_breakpoint_slot_setup(slots, max_slots, bp, ops);
> +
> + if (WARN_ONCE(i < 0, "Can't find any breakpoint slot"))
> + return i;
> +
> + switch (ops) {
> + case HW_BREAKPOINT_INSTALL:
> + /* Set the FWPnCFG/MWPnCFG 1~3 register. */
> + write_wb_reg(CSR_CFG_ADDR, i, 0, info->address);
> + write_wb_reg(CSR_CFG_ADDR, i, 1, info->address);
> + if (info->mask) {
> + write_wb_reg(CSR_CFG_MASK, i, 0, info->mask);
> + write_wb_reg(CSR_CFG_MASK, i, 1, info->mask);
> + }
> + write_wb_reg(CSR_CFG_ASID, i, 0, 0);
> + write_wb_reg(CSR_CFG_ASID, i, 1, 0);
> + ctrl = encode_ctrl_reg(info->ctrl);
> + if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE)
> + write_wb_reg(CSR_CFG_CTRL, i, 0, ctrl | 0x1e);
> + else
> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl | 0x1e | 1 << 8 | 1 << 9);
> +
> + enable = csr_read64(LOONGARCH_CSR_CRMD);
> + csr_write64(1 << 9 | enable, LOONGARCH_CSR_CRMD);
> + break;
> + case HW_BREAKPOINT_UNINSTALL:
> + /* Reset the FWPnCFG/MWPnCFG 1~3 register. */
> + write_wb_reg(CSR_CFG_ADDR, i, 0, 0);
> + write_wb_reg(CSR_CFG_ADDR, i, 1, 0);
> + write_wb_reg(CSR_CFG_MASK, i, 0, 0);
> + write_wb_reg(CSR_CFG_MASK, i, 1, 0);
> + write_wb_reg(CSR_CFG_CTRL, i, 0, 0);
> + write_wb_reg(CSR_CFG_CTRL, i, 1, 0);
> + write_wb_reg(CSR_CFG_ASID, i, 0, 0);
> + write_wb_reg(CSR_CFG_ASID, i, 1, 0);
> + break;
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * Install a perf counter breakpoint.
> + */
> +int arch_install_hw_breakpoint(struct perf_event *bp)
> +{
> + return hw_breakpoint_control(bp, HW_BREAKPOINT_INSTALL);
> +}
> +
> +void arch_uninstall_hw_breakpoint(struct perf_event *bp)
> +{
> + hw_breakpoint_control(bp, HW_BREAKPOINT_UNINSTALL);
> +}
> +
> +static int get_hbp_len(u8 hbp_len)
> +{
> + unsigned int len_in_bytes = 0;
> +
> + switch (hbp_len) {
> + case LOONGARCH_BREAKPOINT_LEN_1:
> + len_in_bytes = 1;
> + break;
> + case LOONGARCH_BREAKPOINT_LEN_2:
> + len_in_bytes = 2;
> + break;
> + case LOONGARCH_BREAKPOINT_LEN_4:
> + len_in_bytes = 4;
> + break;
> + case LOONGARCH_BREAKPOINT_LEN_8:
> + len_in_bytes = 8;
> + break;
> + }
> +
> + return len_in_bytes;
> +}
> +
> +/*
> + * Check whether bp virtual address is in kernel space.
> + */
> +int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw)
> +{
> + unsigned int len;
> + unsigned long va;
> +
> + va = hw->address;
> + len = get_hbp_len(hw->ctrl.len);
> +
> + return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
> +}
> +
> +/*
> + * Construct an arch_hw_breakpoint from a perf_event.
> + */
> +static int arch_build_bp_info(struct perf_event *bp,
> + const struct perf_event_attr *attr,
> + struct arch_hw_breakpoint *hw)
> +{
> + /* Type */
> + switch (attr->bp_type) {
> + case HW_BREAKPOINT_X:
> + hw->ctrl.type = LOONGARCH_BREAKPOINT_EXECUTE;
> + break;
> + case HW_BREAKPOINT_R:
> + hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD;
> + break;
> + case HW_BREAKPOINT_W:
> + hw->ctrl.type = LOONGARCH_BREAKPOINT_STORE;
> + break;
> + case HW_BREAKPOINT_RW:
> + hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD | LOONGARCH_BREAKPOINT_STORE;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + /* Len */
> + switch (attr->bp_len) {
> + case HW_BREAKPOINT_LEN_1:
> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_1;
> + break;
> + case HW_BREAKPOINT_LEN_2:
> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_2;
> + break;
> + case HW_BREAKPOINT_LEN_4:
> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_4;
> + break;
> + case HW_BREAKPOINT_LEN_8:
> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_8;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + /* Address */
> + hw->address = attr->bp_addr;
> +
> + return 0;
> +}
> +
> +/*
> + * Validate the arch-specific HW Breakpoint register settings.
> + */
> +int hw_breakpoint_arch_parse(struct perf_event *bp,
> + const struct perf_event_attr *attr,
> + struct arch_hw_breakpoint *hw)
> +{
> + int ret;
> + u64 alignment_mask, offset;
> +
> + /* Build the arch_hw_breakpoint. */
> + ret = arch_build_bp_info(bp, attr, hw);
> + if (ret)
> + return ret;
> +
> + if (hw->ctrl.type != LOONGARCH_BREAKPOINT_EXECUTE)
> + alignment_mask = 0x7;
> + offset = hw->address & alignment_mask;
> +
> + hw->address &= ~alignment_mask;
> + hw->ctrl.len <<= offset;
> +
> + return 0;
> +}
> +
> +#define PRMD_WE (1UL<<3) /*prmd watch enable, restore to crmd when eret*/
> +static void update_bp_registers(struct pt_regs *regs, int enable)
> +{
> + int i, max_slots;
> + u32 ctrl;
> + struct perf_event **slots;
> +
> + if (csr_read64(LOONGARCH_CSR_FWPS) & 0xff) {
> + slots = this_cpu_ptr(bp_on_reg);
> + max_slots = core_num_brps;
> +
> + } else if (csr_read64(LOONGARCH_CSR_MWPS) & 0xff) {
> + slots = this_cpu_ptr(wp_on_reg);
> + max_slots = core_num_wrps;
> + } else {
> + return;
> + }
> +
> + for (i = 0; i < max_slots; ++i) {
> + if (!slots[i])
> + continue;
> +
> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
> + if (enable) {
> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
> + ctrl |= 0x1 << 8;
> + ctrl |= 0x1 << 9;
> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
> + regs->csr_prmd |= PRMD_WE;
> + } else {
> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
> + ctrl &= ~0x1 << 8;
> + ctrl &= ~0x1 << 9;
> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
> + regs->csr_prmd &= ~PRMD_WE;
> + }
> + }
> +}
> +NOKPROBE_SYMBOL(update_bp_registers);
> +
> +/*
> + * Debug exception handlers.
> + */
> +int breakpoint_handler(struct pt_regs *regs)
> +{
> + int i;
> + u64 addr;
> + struct perf_event *bp, **slots;
> +
> + slots = this_cpu_ptr(bp_on_reg);
> +
> + for (i = 0; i < core_num_brps; ++i) {
> + bp = slots[i];
> + if (bp == NULL)
> + continue;
> + perf_bp_event(bp, regs);
> + }
> + update_bp_registers(regs, 0);
> +
> + return 0;
> +}
> +NOKPROBE_SYMBOL(breakpoint_handler);
> +
> +int watchpoint_handler(struct pt_regs *regs)
> +{
> + int i;
> + struct perf_event *wp, **slots;
> +
> + slots = this_cpu_ptr(wp_on_reg);
> +
> + for (i = 0; i < core_num_wrps; ++i) {
> + wp = slots[i];
> + if (wp == NULL)
> + continue;
> + perf_bp_event(wp, regs);
> + }
> + update_bp_registers(regs, 0);
> +
> + return 0;
> +}
> +NOKPROBE_SYMBOL(watchpoint_handler);
> +
> +/*
> + * One-time initialisation.
> + */
> +static int __init arch_hw_breakpoint_init(void)
> +{
> + core_num_brps = get_num_brps();
> + core_num_wrps = get_num_wrps();
> +
> + pr_info("found %d breakpoint and %d watchpoint registers.\n",
> + core_num_brps, core_num_wrps);
> + return 0;
> +}
> +arch_initcall(arch_hw_breakpoint_init);
> +
> +void hw_breakpoint_thread_switch(struct task_struct *next)
> +{
> + struct pt_regs *regs = task_pt_regs(next);
> +
> + /* Update breakpoints/watchpoints. */
> + update_bp_registers(regs, 1);
> +}
> +
> +void hw_breakpoint_pmu_read(struct perf_event *bp)
> +{
> +}
> +
> +/*
> + * Dummy function to register with die_notifier.
> + */
> +int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
> + unsigned long val, void *data)
> +{
> + return NOTIFY_DONE;
> +}
> diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c
> index 27c8cacbce01..f78574562329 100644
> --- a/arch/loongarch/kernel/process.c
> +++ b/arch/loongarch/kernel/process.c
> @@ -37,6 +37,7 @@
> #include <asm/cpu.h>
> #include <asm/elf.h>
> #include <asm/fpu.h>
> +#include <linux/hw_breakpoint.h>
> #include <asm/io.h>
> #include <asm/irq.h>
> #include <asm/irq_regs.h>
> @@ -100,6 +101,11 @@ void exit_thread(struct task_struct *tsk)
> {
> }
>
> +void flush_thread(void)
> +{
> + flush_ptrace_hw_breakpoint(current);
> +}
> +
> int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
> {
> /*
> @@ -186,6 +192,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
> if (clone_flags & CLONE_SETTLS)
> childregs->regs[2] = tls;
>
> + ptrace_hw_copy_thread(p);
> +
> out:
> clear_tsk_thread_flag(p, TIF_USEDFPU);
> clear_tsk_thread_flag(p, TIF_USEDSIMD);
> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
> index 4d9f77565703..d59cf93a4c31 100644
> --- a/arch/loongarch/kernel/traps.c
> +++ b/arch/loongarch/kernel/traps.c
> @@ -45,6 +45,7 @@
> #include <asm/tlb.h>
> #include <asm/types.h>
> #include <asm/unwind.h>
> +#include <asm/hw_breakpoint.h>
>
> #include "access-helper.h"
>
> @@ -514,7 +515,19 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs)
>
> asmlinkage void noinstr do_watch(struct pt_regs *regs)
> {
> - pr_warn("Hardware watch point handler not implemented!\n");
> + enum ctx_state prev_state;
> +
> + prev_state = exception_enter();
> +
> +#ifdef CONFIG_HAVE_HW_BREAKPOINT
> + if (breakpoint_handler(regs))
> + return;
> + if (watchpoint_handler(regs))
> + return;
> +#endif
> + force_sig(SIGTRAP);
> + exception_exit(prev_state);
> + return;
> }
>
> asmlinkage void noinstr do_ri(struct pt_regs *regs)
>
Hi, Youling
On 2022/12/19 上午11:03, Youling Tang wrote:
> Hi, Qing
>
> On 12/13/2022 05:10 PM, qing zhang wrote:
>> From: Qing Zhang <[email protected]>
>>
>> Use perf framework to manage hardware instruction and data breakpoints.
>> LoongArch defines hardware watchpoint functions for instruction fetch
>> and load/store operations, after the software configures hardware
>> watchpoints
>> for instruction fetch and load/store operations. The processor
>> hardware will
>> monitor the access address of the instruction fetch and load/store
>> operation,
>> and will trigger the exception of the watchpoint when it meets the
>> conditions
>> set by the watchpoint.
>>
>> The hardware monitoring points for instruction fetching and load/store
>> operations
>> each have a register for the overall configuration of all monitoring
>> points,
>> a register for recording the status of all monitoring points, and four
>> registers
>> required for configuration of each watchpoint individually.
>>
>> Watchpoint related control status register chapters:
>> https://github.com/loongson/LoongArch-Documentation/releases/download/2022.08.12/
>>
>> LoongArch-Vol1-v1.02-CN.pdf
>>
>> Initial version has the following limitations:
>> - userspace debug is not yet enabled: work on ptrace/gdb is in progress
>> - no support for virtualization
>>
>> Despite missing userspace debug, initial implementation can be tested:
>> e.g.
>> see samples/hw_breakpoint and register_wide_hw_breakpoint.
>
> Perhaps the existing test phenomenon should be exported to give an
> intuitive sense of this feature.
>
Well, I'll add more detailed output in the next edition.
Thank,
-Qing
> Thanks,
> Youling.
>
>>
>> TODO:
>> - Add Kernel tools that use hardware breakpoints: Kgdb, Ptrace
>> - Add hardware breakpoints/watchpoints for gdb
>>
>> Signed-off-by: Qing Zhang <[email protected]>
>>
>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
>> index 12571eedc488..69199812fe74 100644
>> --- a/arch/loongarch/Kconfig
>> +++ b/arch/loongarch/Kconfig
>> @@ -99,6 +99,7 @@ config LOONGARCH
>> select HAVE_FUNCTION_GRAPH_TRACER
>> select HAVE_FUNCTION_TRACER
>> select HAVE_GENERIC_VDSO
>> + select HAVE_HW_BREAKPOINT if PERF_EVENTS
>> select HAVE_IOREMAP_PROT
>> select HAVE_IRQ_EXIT_ON_IRQ_STACK
>> select HAVE_IRQ_TIME_ACCOUNTING
>> diff --git a/arch/loongarch/include/asm/hw_breakpoint.h
>> b/arch/loongarch/include/asm/hw_breakpoint.h
>> new file mode 100644
>> index 000000000000..a57caf117960
>> --- /dev/null
>> +++ b/arch/loongarch/include/asm/hw_breakpoint.h
>> @@ -0,0 +1,140 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>> + */
>> +#ifndef __ASM_HW_BREAKPOINT_H
>> +#define __ASM_HW_BREAKPOINT_H
>> +
>> +#include <asm/loongarch.h>
>> +
>> +#ifdef __KERNEL__
>> +
>> +/* Breakpoint */
>> +#define LOONGARCH_BREAKPOINT_EXECUTE (0 << 0)
>> +
>> +/* Watchpoints */
>> +#define LOONGARCH_BREAKPOINT_LOAD (1 << 0)
>> +#define LOONGARCH_BREAKPOINT_STORE (1 << 1)
>> +
>> +struct arch_hw_breakpoint_ctrl {
>> + u32 __reserved : 28,
>> + type : 2,
>> + len : 2;
>> +};
>> +
>> +struct arch_hw_breakpoint {
>> + u64 address;
>> + u64 mask;
>> + struct arch_hw_breakpoint_ctrl ctrl;
>> +};
>> +
>> +/* Lengths */
>> +#define LOONGARCH_BREAKPOINT_LEN_1 0b11
>> +#define LOONGARCH_BREAKPOINT_LEN_2 0b10
>> +#define LOONGARCH_BREAKPOINT_LEN_4 0b01
>> +#define LOONGARCH_BREAKPOINT_LEN_8 0b00
>> +
>> +/*
>> + * Limits.
>> + * Changing these will require modifications to the register accessors.
>> + */
>> +#define LOONGARCH_MAX_BRP 8
>> +#define LOONGARCH_MAX_WRP 8
>> +
>> +/* Virtual debug register bases. */
>> +#define CSR_CFG_ADDR 0
>> +#define CSR_CFG_MASK (CSR_CFG_ADDR + LOONGARCH_MAX_BRP)
>> +#define CSR_CFG_CTRL (CSR_CFG_MASK + LOONGARCH_MAX_BRP)
>> +#define CSR_CFG_ASID (CSR_CFG_CTRL + LOONGARCH_MAX_WRP)
>> +
>> +/* Debug register names. */
>> +#define LOONGARCH_CSR_NAME_ADDR ADDR
>> +#define LOONGARCH_CSR_NAME_MASK MASK
>> +#define LOONGARCH_CSR_NAME_CTRL CTRL
>> +#define LOONGARCH_CSR_NAME_ASID ASID
>> +
>> +/* Accessor macros for the debug registers. */
>> +#define LOONGARCH_CSR_READ(N, REG, T, VAL) \
>> +do { \
>> + if (T == 0) \
>> + VAL = csr_read64(LOONGARCH_CSR_##IB##N##REG); \
>> + else \
>> + VAL = csr_read64(LOONGARCH_CSR_##DB##N##REG); \
>> +} while (0)
>> +
>> +#define LOONGARCH_CSR_WRITE(N, REG, T, VAL) \
>> +do { \
>> + if (T == 0) \
>> + csr_write64(VAL, LOONGARCH_CSR_##IB##N##REG); \
>> + else \
>> + csr_write64(VAL, LOONGARCH_CSR_##DB##N##REG); \
>> +} while (0)
>> +
>> +static inline u32 encode_ctrl_reg(struct arch_hw_breakpoint_ctrl ctrl)
>> +{
>> + u32 val = (ctrl.len << 2) | ctrl.type;
>> +
>> + return val;
>> +}
>> +
>> +static inline void decode_ctrl_reg(u32 reg, struct
>> arch_hw_breakpoint_ctrl *ctrl)
>> +{
>> + ctrl->type = reg & 0x3;
>> + reg >>= 2;
>> + ctrl->len = reg & 0x3;
>> +}
>> +
>> +struct task_struct;
>> +struct notifier_block;
>> +struct perf_event_attr;
>> +struct perf_event;
>> +
>> +extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
>> + int *gen_len, int *gen_type, int *offset);
>> +extern int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw);
>> +extern int hw_breakpoint_arch_parse(struct perf_event *bp,
>> + const struct perf_event_attr *attr,
>> + struct arch_hw_breakpoint *hw);
>> +extern int hw_breakpoint_exceptions_notify(struct notifier_block
>> *unused,
>> + unsigned long val, void *data);
>> +
>> +extern int arch_install_hw_breakpoint(struct perf_event *bp);
>> +extern void arch_uninstall_hw_breakpoint(struct perf_event *bp);
>> +extern void hw_breakpoint_pmu_read(struct perf_event *bp);
>> +extern int hw_breakpoint_slots(int type);
>> +
>> +int breakpoint_handler(struct pt_regs *regs);
>> +int watchpoint_handler(struct pt_regs *regs);
>> +
>> +#ifdef CONFIG_HAVE_HW_BREAKPOINT
>> +extern void hw_breakpoint_thread_switch(struct task_struct *next);
>> +extern void ptrace_hw_copy_thread(struct task_struct *task);
>> +#else
>> +static inline void hw_breakpoint_thread_switch(struct task_struct *next)
>> +{
>> +}
>> +static inline void ptrace_hw_copy_thread(struct task_struct *task)
>> +{
>> +}
>> +#endif
>> +
>> +/* Determine number of BRP registers available. */
>> +static inline int get_num_brps(void)
>> +{
>> + unsigned int ibcn;
>> +
>> + ibcn = csr_read64(LOONGARCH_CSR_FWPC) & 0x3f;
>> + return ibcn;
>> +}
>> +
>> +/* Determine number of WRP registers available. */
>> +static inline int get_num_wrps(void)
>> +{
>> + unsigned int dbcn;
>> +
>> + dbcn = csr_read64(LOONGARCH_CSR_MWPC) & 0x3f;
>> + return dbcn;
>> +}
>> +
>> +#endif /* __KERNEL__ */
>> +#endif /* __ASM_BREAKPOINT_H */
>> diff --git a/arch/loongarch/include/asm/loongarch.h
>> b/arch/loongarch/include/asm/loongarch.h
>> index 7f8d57a61c8b..e9aed583a064 100644
>> --- a/arch/loongarch/include/asm/loongarch.h
>> +++ b/arch/loongarch/include/asm/loongarch.h
>> @@ -970,42 +970,42 @@ static __always_inline void iocsr_write64(u64
>> val, u32 reg)
>>
>> #define LOONGARCH_CSR_DB0ADDR 0x310 /* data breakpoint 0
>> address */
>> #define LOONGARCH_CSR_DB0MASK 0x311 /* data breakpoint 0
>> mask */
>> -#define LOONGARCH_CSR_DB0CTL 0x312 /* data breakpoint 0
>> control */
>> +#define LOONGARCH_CSR_DB0CTRL 0x312 /* data breakpoint 0
>> control */
>> #define LOONGARCH_CSR_DB0ASID 0x313 /* data breakpoint 0
>> asid */
>>
>> #define LOONGARCH_CSR_DB1ADDR 0x318 /* data breakpoint 1
>> address */
>> #define LOONGARCH_CSR_DB1MASK 0x319 /* data breakpoint 1
>> mask */
>> -#define LOONGARCH_CSR_DB1CTL 0x31a /* data breakpoint 1
>> control */
>> +#define LOONGARCH_CSR_DB1CTRL 0x31a /* data breakpoint 1
>> control */
>> #define LOONGARCH_CSR_DB1ASID 0x31b /* data breakpoint 1
>> asid */
>>
>> #define LOONGARCH_CSR_DB2ADDR 0x320 /* data breakpoint 2
>> address */
>> #define LOONGARCH_CSR_DB2MASK 0x321 /* data breakpoint 2
>> mask */
>> -#define LOONGARCH_CSR_DB2CTL 0x322 /* data breakpoint 2
>> control */
>> +#define LOONGARCH_CSR_DB2CTRL 0x322 /* data breakpoint 2
>> control */
>> #define LOONGARCH_CSR_DB2ASID 0x323 /* data breakpoint 2
>> asid */
>>
>> #define LOONGARCH_CSR_DB3ADDR 0x328 /* data breakpoint 3
>> address */
>> #define LOONGARCH_CSR_DB3MASK 0x329 /* data breakpoint 3
>> mask */
>> -#define LOONGARCH_CSR_DB3CTL 0x32a /* data breakpoint 3
>> control */
>> +#define LOONGARCH_CSR_DB3CTRL 0x32a /* data breakpoint 3
>> control */
>> #define LOONGARCH_CSR_DB3ASID 0x32b /* data breakpoint 3
>> asid */
>>
>> #define LOONGARCH_CSR_DB4ADDR 0x330 /* data breakpoint 4
>> address */
>> #define LOONGARCH_CSR_DB4MASK 0x331 /* data breakpoint 4
>> maks */
>> -#define LOONGARCH_CSR_DB4CTL 0x332 /* data breakpoint 4
>> control */
>> +#define LOONGARCH_CSR_DB4CTRL 0x332 /* data breakpoint 4
>> control */
>> #define LOONGARCH_CSR_DB4ASID 0x333 /* data breakpoint 4
>> asid */
>>
>> #define LOONGARCH_CSR_DB5ADDR 0x338 /* data breakpoint 5
>> address */
>> #define LOONGARCH_CSR_DB5MASK 0x339 /* data breakpoint 5
>> mask */
>> -#define LOONGARCH_CSR_DB5CTL 0x33a /* data breakpoint 5
>> control */
>> +#define LOONGARCH_CSR_DB5CTRL 0x33a /* data breakpoint 5
>> control */
>> #define LOONGARCH_CSR_DB5ASID 0x33b /* data breakpoint 5
>> asid */
>>
>> #define LOONGARCH_CSR_DB6ADDR 0x340 /* data breakpoint 6
>> address */
>> #define LOONGARCH_CSR_DB6MASK 0x341 /* data breakpoint 6
>> mask */
>> -#define LOONGARCH_CSR_DB6CTL 0x342 /* data breakpoint 6
>> control */
>> +#define LOONGARCH_CSR_DB6CTRL 0x342 /* data breakpoint 6
>> control */
>> #define LOONGARCH_CSR_DB6ASID 0x343 /* data breakpoint 6
>> asid */
>>
>> #define LOONGARCH_CSR_DB7ADDR 0x348 /* data breakpoint 7
>> address */
>> #define LOONGARCH_CSR_DB7MASK 0x349 /* data breakpoint 7
>> mask */
>> -#define LOONGARCH_CSR_DB7CTL 0x34a /* data breakpoint 7
>> control */
>> +#define LOONGARCH_CSR_DB7CTRL 0x34a /* data breakpoint 7
>> control */
>> #define LOONGARCH_CSR_DB7ASID 0x34b /* data breakpoint 7
>> asid */
>>
>> #define LOONGARCH_CSR_FWPC 0x380 /* instruction breakpoint
>> config */
>> @@ -1013,42 +1013,42 @@ static __always_inline void iocsr_write64(u64
>> val, u32 reg)
>>
>> #define LOONGARCH_CSR_IB0ADDR 0x390 /* inst breakpoint 0
>> address */
>> #define LOONGARCH_CSR_IB0MASK 0x391 /* inst breakpoint 0
>> mask */
>> -#define LOONGARCH_CSR_IB0CTL 0x392 /* inst breakpoint 0
>> control */
>> +#define LOONGARCH_CSR_IB0CTRL 0x392 /* inst breakpoint 0
>> control */
>> #define LOONGARCH_CSR_IB0ASID 0x393 /* inst breakpoint 0
>> asid */
>>
>> #define LOONGARCH_CSR_IB1ADDR 0x398 /* inst breakpoint 1
>> address */
>> #define LOONGARCH_CSR_IB1MASK 0x399 /* inst breakpoint 1
>> mask */
>> -#define LOONGARCH_CSR_IB1CTL 0x39a /* inst breakpoint 1
>> control */
>> +#define LOONGARCH_CSR_IB1CTRL 0x39a /* inst breakpoint 1
>> control */
>> #define LOONGARCH_CSR_IB1ASID 0x39b /* inst breakpoint 1
>> asid */
>>
>> #define LOONGARCH_CSR_IB2ADDR 0x3a0 /* inst breakpoint 2
>> address */
>> #define LOONGARCH_CSR_IB2MASK 0x3a1 /* inst breakpoint 2
>> mask */
>> -#define LOONGARCH_CSR_IB2CTL 0x3a2 /* inst breakpoint 2
>> control */
>> +#define LOONGARCH_CSR_IB2CTRL 0x3a2 /* inst breakpoint 2
>> control */
>> #define LOONGARCH_CSR_IB2ASID 0x3a3 /* inst breakpoint 2
>> asid */
>>
>> #define LOONGARCH_CSR_IB3ADDR 0x3a8 /* inst breakpoint 3
>> address */
>> #define LOONGARCH_CSR_IB3MASK 0x3a9 /* breakpoint 3 mask */
>> -#define LOONGARCH_CSR_IB3CTL 0x3aa /* inst breakpoint 3
>> control */
>> +#define LOONGARCH_CSR_IB3CTRL 0x3aa /* inst breakpoint 3
>> control */
>> #define LOONGARCH_CSR_IB3ASID 0x3ab /* inst breakpoint 3
>> asid */
>>
>> #define LOONGARCH_CSR_IB4ADDR 0x3b0 /* inst breakpoint 4
>> address */
>> #define LOONGARCH_CSR_IB4MASK 0x3b1 /* inst breakpoint 4
>> mask */
>> -#define LOONGARCH_CSR_IB4CTL 0x3b2 /* inst breakpoint 4
>> control */
>> +#define LOONGARCH_CSR_IB4CTRL 0x3b2 /* inst breakpoint 4
>> control */
>> #define LOONGARCH_CSR_IB4ASID 0x3b3 /* inst breakpoint 4
>> asid */
>>
>> #define LOONGARCH_CSR_IB5ADDR 0x3b8 /* inst breakpoint 5
>> address */
>> #define LOONGARCH_CSR_IB5MASK 0x3b9 /* inst breakpoint 5
>> mask */
>> -#define LOONGARCH_CSR_IB5CTL 0x3ba /* inst breakpoint 5
>> control */
>> +#define LOONGARCH_CSR_IB5CTRL 0x3ba /* inst breakpoint 5
>> control */
>> #define LOONGARCH_CSR_IB5ASID 0x3bb /* inst breakpoint 5
>> asid */
>>
>> #define LOONGARCH_CSR_IB6ADDR 0x3c0 /* inst breakpoint 6
>> address */
>> #define LOONGARCH_CSR_IB6MASK 0x3c1 /* inst breakpoint 6
>> mask */
>> -#define LOONGARCH_CSR_IB6CTL 0x3c2 /* inst breakpoint 6
>> control */
>> +#define LOONGARCH_CSR_IB6CTRL 0x3c2 /* inst breakpoint 6
>> control */
>> #define LOONGARCH_CSR_IB6ASID 0x3c3 /* inst breakpoint 6
>> asid */
>>
>> #define LOONGARCH_CSR_IB7ADDR 0x3c8 /* inst breakpoint 7
>> address */
>> #define LOONGARCH_CSR_IB7MASK 0x3c9 /* inst breakpoint 7
>> mask */
>> -#define LOONGARCH_CSR_IB7CTL 0x3ca /* inst breakpoint 7
>> control */
>> +#define LOONGARCH_CSR_IB7CTRL 0x3ca /* inst breakpoint 7
>> control */
>> #define LOONGARCH_CSR_IB7ASID 0x3cb /* inst breakpoint 7
>> asid */
>>
>> #define LOONGARCH_CSR_DEBUG 0x500 /* debug config */
>> diff --git a/arch/loongarch/include/asm/processor.h
>> b/arch/loongarch/include/asm/processor.h
>> index 7184f1dc61f2..f6ee920122d6 100644
>> --- a/arch/loongarch/include/asm/processor.h
>> +++ b/arch/loongarch/include/asm/processor.h
>> @@ -11,6 +11,7 @@
>>
>> #include <asm/cpu.h>
>> #include <asm/cpu-info.h>
>> +#include <asm/hw_breakpoint.h>
>> #include <asm/loongarch.h>
>> #include <asm/vdso/processor.h>
>> #include <uapi/asm/ptrace.h>
>> @@ -131,6 +132,9 @@ struct thread_struct {
>> * they are conditionally copied at fork().
>> */
>> struct loongarch_fpu fpu FPU_ALIGN;
>> + /* Hardware breakpoints pinned to this task. */
>> + struct perf_event *hbp_break[LOONGARCH_MAX_BRP];
>> + struct perf_event *hbp_watch[LOONGARCH_MAX_WRP];
>> };
>>
>> #define thread_saved_ra(tsk) (tsk->thread.sched_ra)
>> @@ -172,6 +176,8 @@ struct thread_struct {
>> .fcc = 0, \
>> .fpr = {{{0,},},}, \
>> }, \
>> + .hbp_break = {0}, \
>> + .hbp_watch = {0}, \
>> }
>>
>> struct task_struct;
>> @@ -184,10 +190,6 @@ extern unsigned long
>> boot_option_idle_override;
>> */
>> extern void start_thread(struct pt_regs *regs, unsigned long pc,
>> unsigned long sp);
>>
>> -static inline void flush_thread(void)
>> -{
>> -}
>> -
>> unsigned long __get_wchan(struct task_struct *p);
>>
>> #define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
>> diff --git a/arch/loongarch/include/asm/switch_to.h
>> b/arch/loongarch/include/asm/switch_to.h
>> index 43a5ab162d38..24e3094bebab 100644
>> --- a/arch/loongarch/include/asm/switch_to.h
>> +++ b/arch/loongarch/include/asm/switch_to.h
>> @@ -34,6 +34,7 @@ extern asmlinkage struct task_struct
>> *__switch_to(struct task_struct *prev,
>> #define switch_to(prev, next, last) \
>> do { \
>> lose_fpu_inatomic(1, prev); \
>> + hw_breakpoint_thread_switch(next); \
>> (last) = __switch_to(prev, next, task_thread_info(next), \
>> __builtin_return_address(0), __builtin_frame_address(0)); \
>> } while (0)
>> diff --git a/arch/loongarch/kernel/Makefile
>> b/arch/loongarch/kernel/Makefile
>> index 7ca65195f7f8..b3aca7f2296e 100644
>> --- a/arch/loongarch/kernel/Makefile
>> +++ b/arch/loongarch/kernel/Makefile
>> @@ -46,6 +46,7 @@ obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
>> obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
>>
>> obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
>> +obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
>>
>> obj-$(CONFIG_KPROBES) += kprobes.o kprobes_trampoline.o
>>
>> diff --git a/arch/loongarch/kernel/hw_breakpoint.c
>> b/arch/loongarch/kernel/hw_breakpoint.c
>> new file mode 100644
>> index 000000000000..16f38ceec321
>> --- /dev/null
>> +++ b/arch/loongarch/kernel/hw_breakpoint.c
>> @@ -0,0 +1,461 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>> + */
>> +#define pr_fmt(fmt) "hw-breakpoint: " fmt
>> +
>> +#include <linux/hw_breakpoint.h>
>> +#include <linux/kprobes.h>
>> +#include <linux/perf_event.h>
>> +
>> +#include <asm/hw_breakpoint.h>
>> +
>> +/* Breakpoint currently in use for each BRP. */
>> +static DEFINE_PER_CPU(struct perf_event *,
>> bp_on_reg[LOONGARCH_MAX_BRP]);
>> +
>> +/* Watchpoint currently in use for each WRP. */
>> +static DEFINE_PER_CPU(struct perf_event *,
>> wp_on_reg[LOONGARCH_MAX_WRP]);
>> +
>> +/* Number of BRP/WRP registers on this CPU. */
>> +static int core_num_brps;
>> +static int core_num_wrps;
>> +
>> +int hw_breakpoint_slots(int type)
>> +{
>> + /*
>> + * We can be called early, so don't rely on
>> + * our static variables being initialised.
>> + */
>> + switch (type) {
>> + case TYPE_INST:
>> + return get_num_brps();
>> + case TYPE_DATA:
>> + return get_num_wrps();
>> + default:
>> + pr_warn("unknown slot type: %d\n", type);
>> + return 0;
>> + }
>> +}
>> +
>> +#define READ_WB_REG_CASE(OFF, N, REG, T, VAL) \
>> + case (OFF + N): \
>> + LOONGARCH_CSR_READ(N, REG, T, VAL); \
>> + break
>> +
>> +#define WRITE_WB_REG_CASE(OFF, N, REG, T, VAL) \
>> + case (OFF + N): \
>> + LOONGARCH_CSR_WRITE(N, REG, T, VAL); \
>> + break
>> +
>> +#define GEN_READ_WB_REG_CASES(OFF, REG, T, VAL) \
>> + READ_WB_REG_CASE(OFF, 0, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 1, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 2, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 3, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 4, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 5, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 6, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 7, REG, T, VAL);
>> +
>> +#define GEN_WRITE_WB_REG_CASES(OFF, REG, T, VAL) \
>> + WRITE_WB_REG_CASE(OFF, 0, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 1, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 2, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 3, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 4, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 5, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 6, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 7, REG, T, VAL);
>> +
>> +static u64 read_wb_reg(int reg, int n, int t)
>> +{
>> + u64 val = 0;
>> +
>> + switch (reg + n) {
>> + GEN_READ_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
>> + GEN_READ_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
>> + GEN_READ_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
>> + GEN_READ_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
>> + default:
>> + pr_warn("attempt to read from unknown breakpoint register
>> %d\n", n);
>> + }
>> +
>> + return val;
>> +}
>> +NOKPROBE_SYMBOL(read_wb_reg);
>> +
>> +static void write_wb_reg(int reg, int n, int t, u64 val)
>> +{
>> + switch (reg + n) {
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
>> + default:
>> + pr_warn("attempt to write to unknown breakpoint register
>> %d\n", n);
>> + }
>> +}
>> +NOKPROBE_SYMBOL(write_wb_reg);
>> +
>> +enum hw_breakpoint_ops {
>> + HW_BREAKPOINT_INSTALL,
>> + HW_BREAKPOINT_UNINSTALL,
>> +};
>> +
>> +/**
>> + * hw_breakpoint_slot_setup - Find and setup a perf slot according to
>> + * operations
>> + *
>> + * @slots: pointer to array of slots
>> + * @max_slots: max number of slots
>> + * @bp: perf_event to setup
>> + * @ops: operation to be carried out on the slot
>> + *
>> + * Return:
>> + * slot index on success
>> + * -ENOSPC if no slot is available/matches
>> + * -EINVAL on wrong operations parameter
>> + */
>> +static int hw_breakpoint_slot_setup(struct perf_event **slots, int
>> max_slots,
>> + struct perf_event *bp,
>> + enum hw_breakpoint_ops ops)
>> +{
>> + int i;
>> + struct perf_event **slot;
>> +
>> + for (i = 0; i < max_slots; ++i) {
>> + slot = &slots[i];
>> + switch (ops) {
>> + case HW_BREAKPOINT_INSTALL:
>> + if (!*slot) {
>> + *slot = bp;
>> + return i;
>> + }
>> + break;
>> + case HW_BREAKPOINT_UNINSTALL:
>> + if (*slot == bp) {
>> + *slot = NULL;
>> + return i;
>> + }
>> + break;
>> + default:
>> + pr_warn_once("Unhandled hw breakpoint ops %d\n", ops);
>> + return -EINVAL;
>> + }
>> + }
>> + return -ENOSPC;
>> +}
>> +
>> +/*
>> + * Unregister breakpoints from this task and reset the pointers in
>> + * the thread_struct.
>> + */
>> +void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
>> +{
>> +}
>> +
>> +void ptrace_hw_copy_thread(struct task_struct *tsk)
>> +{
>> + memset(&tsk->thread.hbp_break, 0, sizeof(tsk->thread.hbp_break));
>> + memset(&tsk->thread.hbp_watch, 0, sizeof(tsk->thread.hbp_watch));
>> +}
>> +
>> +static int hw_breakpoint_control(struct perf_event *bp,
>> + enum hw_breakpoint_ops ops)
>> +{
>> + struct arch_hw_breakpoint *info = counter_arch_bp(bp);
>> + struct perf_event **slots;
>> + int i, max_slots, enable;
>> + u32 ctrl;
>> + struct pt_regs *regs = task_pt_regs(current);
>> +
>> + if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
>> + /* Breakpoint */
>> + slots = this_cpu_ptr(bp_on_reg);
>> + max_slots = core_num_brps;
>> + } else {
>> + /* Watchpoint */
>> + slots = this_cpu_ptr(wp_on_reg);
>> + max_slots = core_num_wrps;
>> + }
>> +
>> + i = hw_breakpoint_slot_setup(slots, max_slots, bp, ops);
>> +
>> + if (WARN_ONCE(i < 0, "Can't find any breakpoint slot"))
>> + return i;
>> +
>> + switch (ops) {
>> + case HW_BREAKPOINT_INSTALL:
>> + /* Set the FWPnCFG/MWPnCFG 1~3 register. */
>> + write_wb_reg(CSR_CFG_ADDR, i, 0, info->address);
>> + write_wb_reg(CSR_CFG_ADDR, i, 1, info->address);
>> + if (info->mask) {
>> + write_wb_reg(CSR_CFG_MASK, i, 0, info->mask);
>> + write_wb_reg(CSR_CFG_MASK, i, 1, info->mask);
>> + }
>> + write_wb_reg(CSR_CFG_ASID, i, 0, 0);
>> + write_wb_reg(CSR_CFG_ASID, i, 1, 0);
>> + ctrl = encode_ctrl_reg(info->ctrl);
>> + if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE)
>> + write_wb_reg(CSR_CFG_CTRL, i, 0, ctrl | 0x1e);
>> + else
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl | 0x1e | 1 << 8 |
>> 1 << 9);
>> +
>> + enable = csr_read64(LOONGARCH_CSR_CRMD);
>> + csr_write64(1 << 9 | enable, LOONGARCH_CSR_CRMD);
>> + break;
>> + case HW_BREAKPOINT_UNINSTALL:
>> + /* Reset the FWPnCFG/MWPnCFG 1~3 register. */
>> + write_wb_reg(CSR_CFG_ADDR, i, 0, 0);
>> + write_wb_reg(CSR_CFG_ADDR, i, 1, 0);
>> + write_wb_reg(CSR_CFG_MASK, i, 0, 0);
>> + write_wb_reg(CSR_CFG_MASK, i, 1, 0);
>> + write_wb_reg(CSR_CFG_CTRL, i, 0, 0);
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, 0);
>> + write_wb_reg(CSR_CFG_ASID, i, 0, 0);
>> + write_wb_reg(CSR_CFG_ASID, i, 1, 0);
>> + break;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +/*
>> + * Install a perf counter breakpoint.
>> + */
>> +int arch_install_hw_breakpoint(struct perf_event *bp)
>> +{
>> + return hw_breakpoint_control(bp, HW_BREAKPOINT_INSTALL);
>> +}
>> +
>> +void arch_uninstall_hw_breakpoint(struct perf_event *bp)
>> +{
>> + hw_breakpoint_control(bp, HW_BREAKPOINT_UNINSTALL);
>> +}
>> +
>> +static int get_hbp_len(u8 hbp_len)
>> +{
>> + unsigned int len_in_bytes = 0;
>> +
>> + switch (hbp_len) {
>> + case LOONGARCH_BREAKPOINT_LEN_1:
>> + len_in_bytes = 1;
>> + break;
>> + case LOONGARCH_BREAKPOINT_LEN_2:
>> + len_in_bytes = 2;
>> + break;
>> + case LOONGARCH_BREAKPOINT_LEN_4:
>> + len_in_bytes = 4;
>> + break;
>> + case LOONGARCH_BREAKPOINT_LEN_8:
>> + len_in_bytes = 8;
>> + break;
>> + }
>> +
>> + return len_in_bytes;
>> +}
>> +
>> +/*
>> + * Check whether bp virtual address is in kernel space.
>> + */
>> +int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw)
>> +{
>> + unsigned int len;
>> + unsigned long va;
>> +
>> + va = hw->address;
>> + len = get_hbp_len(hw->ctrl.len);
>> +
>> + return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
>> +}
>> +
>> +/*
>> + * Construct an arch_hw_breakpoint from a perf_event.
>> + */
>> +static int arch_build_bp_info(struct perf_event *bp,
>> + const struct perf_event_attr *attr,
>> + struct arch_hw_breakpoint *hw)
>> +{
>> + /* Type */
>> + switch (attr->bp_type) {
>> + case HW_BREAKPOINT_X:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_EXECUTE;
>> + break;
>> + case HW_BREAKPOINT_R:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD;
>> + break;
>> + case HW_BREAKPOINT_W:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_STORE;
>> + break;
>> + case HW_BREAKPOINT_RW:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD |
>> LOONGARCH_BREAKPOINT_STORE;
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + /* Len */
>> + switch (attr->bp_len) {
>> + case HW_BREAKPOINT_LEN_1:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_1;
>> + break;
>> + case HW_BREAKPOINT_LEN_2:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_2;
>> + break;
>> + case HW_BREAKPOINT_LEN_4:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_4;
>> + break;
>> + case HW_BREAKPOINT_LEN_8:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_8;
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + /* Address */
>> + hw->address = attr->bp_addr;
>> +
>> + return 0;
>> +}
>> +
>> +/*
>> + * Validate the arch-specific HW Breakpoint register settings.
>> + */
>> +int hw_breakpoint_arch_parse(struct perf_event *bp,
>> + const struct perf_event_attr *attr,
>> + struct arch_hw_breakpoint *hw)
>> +{
>> + int ret;
>> + u64 alignment_mask, offset;
>> +
>> + /* Build the arch_hw_breakpoint. */
>> + ret = arch_build_bp_info(bp, attr, hw);
>> + if (ret)
>> + return ret;
>> +
>> + if (hw->ctrl.type != LOONGARCH_BREAKPOINT_EXECUTE)
>> + alignment_mask = 0x7;
>> + offset = hw->address & alignment_mask;
>> +
>> + hw->address &= ~alignment_mask;
>> + hw->ctrl.len <<= offset;
>> +
>> + return 0;
>> +}
>> +
>> +#define PRMD_WE (1UL<<3) /*prmd watch enable, restore to crmd when
>> eret*/
>> +static void update_bp_registers(struct pt_regs *regs, int enable)
>> +{
>> + int i, max_slots;
>> + u32 ctrl;
>> + struct perf_event **slots;
>> +
>> + if (csr_read64(LOONGARCH_CSR_FWPS) & 0xff) {
>> + slots = this_cpu_ptr(bp_on_reg);
>> + max_slots = core_num_brps;
>> +
>> + } else if (csr_read64(LOONGARCH_CSR_MWPS) & 0xff) {
>> + slots = this_cpu_ptr(wp_on_reg);
>> + max_slots = core_num_wrps;
>> + } else {
>> + return;
>> + }
>> +
>> + for (i = 0; i < max_slots; ++i) {
>> + if (!slots[i])
>> + continue;
>> +
>> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
>> + if (enable) {
>> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
>> + ctrl |= 0x1 << 8;
>> + ctrl |= 0x1 << 9;
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
>> + regs->csr_prmd |= PRMD_WE;
>> + } else {
>> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
>> + ctrl &= ~0x1 << 8;
>> + ctrl &= ~0x1 << 9;
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
>> + regs->csr_prmd &= ~PRMD_WE;
>> + }
>> + }
>> +}
>> +NOKPROBE_SYMBOL(update_bp_registers);
>> +
>> +/*
>> + * Debug exception handlers.
>> + */
>> +int breakpoint_handler(struct pt_regs *regs)
>> +{
>> + int i;
>> + u64 addr;
>> + struct perf_event *bp, **slots;
>> +
>> + slots = this_cpu_ptr(bp_on_reg);
>> +
>> + for (i = 0; i < core_num_brps; ++i) {
>> + bp = slots[i];
>> + if (bp == NULL)
>> + continue;
>> + perf_bp_event(bp, regs);
>> + }
>> + update_bp_registers(regs, 0);
>> +
>> + return 0;
>> +}
>> +NOKPROBE_SYMBOL(breakpoint_handler);
>> +
>> +int watchpoint_handler(struct pt_regs *regs)
>> +{
>> + int i;
>> + struct perf_event *wp, **slots;
>> +
>> + slots = this_cpu_ptr(wp_on_reg);
>> +
>> + for (i = 0; i < core_num_wrps; ++i) {
>> + wp = slots[i];
>> + if (wp == NULL)
>> + continue;
>> + perf_bp_event(wp, regs);
>> + }
>> + update_bp_registers(regs, 0);
>> +
>> + return 0;
>> +}
>> +NOKPROBE_SYMBOL(watchpoint_handler);
>> +
>> +/*
>> + * One-time initialisation.
>> + */
>> +static int __init arch_hw_breakpoint_init(void)
>> +{
>> + core_num_brps = get_num_brps();
>> + core_num_wrps = get_num_wrps();
>> +
>> + pr_info("found %d breakpoint and %d watchpoint registers.\n",
>> + core_num_brps, core_num_wrps);
>> + return 0;
>> +}
>> +arch_initcall(arch_hw_breakpoint_init);
>> +
>> +void hw_breakpoint_thread_switch(struct task_struct *next)
>> +{
>> + struct pt_regs *regs = task_pt_regs(next);
>> +
>> + /* Update breakpoints/watchpoints. */
>> + update_bp_registers(regs, 1);
>> +}
>> +
>> +void hw_breakpoint_pmu_read(struct perf_event *bp)
>> +{
>> +}
>> +
>> +/*
>> + * Dummy function to register with die_notifier.
>> + */
>> +int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
>> + unsigned long val, void *data)
>> +{
>> + return NOTIFY_DONE;
>> +}
>> diff --git a/arch/loongarch/kernel/process.c
>> b/arch/loongarch/kernel/process.c
>> index 27c8cacbce01..f78574562329 100644
>> --- a/arch/loongarch/kernel/process.c
>> +++ b/arch/loongarch/kernel/process.c
>> @@ -37,6 +37,7 @@
>> #include <asm/cpu.h>
>> #include <asm/elf.h>
>> #include <asm/fpu.h>
>> +#include <linux/hw_breakpoint.h>
>> #include <asm/io.h>
>> #include <asm/irq.h>
>> #include <asm/irq_regs.h>
>> @@ -100,6 +101,11 @@ void exit_thread(struct task_struct *tsk)
>> {
>> }
>>
>> +void flush_thread(void)
>> +{
>> + flush_ptrace_hw_breakpoint(current);
>> +}
>> +
>> int arch_dup_task_struct(struct task_struct *dst, struct task_struct
>> *src)
>> {
>> /*
>> @@ -186,6 +192,8 @@ int copy_thread(struct task_struct *p, const
>> struct kernel_clone_args *args)
>> if (clone_flags & CLONE_SETTLS)
>> childregs->regs[2] = tls;
>>
>> + ptrace_hw_copy_thread(p);
>> +
>> out:
>> clear_tsk_thread_flag(p, TIF_USEDFPU);
>> clear_tsk_thread_flag(p, TIF_USEDSIMD);
>> diff --git a/arch/loongarch/kernel/traps.c
>> b/arch/loongarch/kernel/traps.c
>> index 4d9f77565703..d59cf93a4c31 100644
>> --- a/arch/loongarch/kernel/traps.c
>> +++ b/arch/loongarch/kernel/traps.c
>> @@ -45,6 +45,7 @@
>> #include <asm/tlb.h>
>> #include <asm/types.h>
>> #include <asm/unwind.h>
>> +#include <asm/hw_breakpoint.h>
>>
>> #include "access-helper.h"
>>
>> @@ -514,7 +515,19 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs)
>>
>> asmlinkage void noinstr do_watch(struct pt_regs *regs)
>> {
>> - pr_warn("Hardware watch point handler not implemented!\n");
>> + enum ctx_state prev_state;
>> +
>> + prev_state = exception_enter();
>> +
>> +#ifdef CONFIG_HAVE_HW_BREAKPOINT
>> + if (breakpoint_handler(regs))
>> + return;
>> + if (watchpoint_handler(regs))
>> + return;
>> +#endif
>> + force_sig(SIGTRAP);
>> + exception_exit(prev_state);
>> + return;
>> }
>>
>> asmlinkage void noinstr do_ri(struct pt_regs *regs)
>>