Hey all,
Just wanted to try to revive Anton's KDB FIQ patches
which have been sent out a number of times since last October
and have gotten almost no response at all.
I've simply updated them to apply to Linus' current HEAD,
and figured I'd send them out again to try to spur some
interest.
Any feedback would be appreciated!
thanks
-john
Short description of the KDB/FIQ debugger:
The FIQ debugger is a facility that can be used to debug situations when
the kernel stuck in uninterruptable sections, e.g. the kernel infinitely
loops or deadlocked in an interrupt or with interrupts disabled. On some
development boards there is even a special NMI button, which is very
useful for debugging weird kernel hangs.
And FIQ is basically an NMI, it has a higher priority than IRQs, and upon
IRQ exception FIQs are not disabled. It is still possible to disable FIQs
(as well as some "NMIs" on other architectures), but via special means.
Old changelogs and a full rationale for these patches can be found here:
v1-v5, rationale: http://lkml.org/lkml/2012/9/10/2
v6: http://lkml.org/lkml/2012/9/10/2
v7: http://lkml.org/lkml/2012/9/13/367
v8: http://lkml.org/lkml/2012/9/19/525
v9: http://lkml.org/lkml/2012/9/24/538
Cc: Anton Vorontsov <[email protected]>
Cc: Russell King <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Jason Wessel <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: [email protected]
Cc: [email protected]
Anton Vorontsov (3):
ARM: Move some macros from entry-armv to entry-header
ARM: Add KGDB/KDB FIQ debugger generic code
ARM: versatile: Make able to use UART ports for KGDB FIQ debugger
arch/arm/Kconfig | 19 +++++
arch/arm/include/asm/kgdb.h | 7 ++
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/entry-armv.S | 169 +-----------------------------------
arch/arm/kernel/entry-header.S | 171 +++++++++++++++++++++++++++++++++++++
arch/arm/kernel/kgdb_fiq.c | 118 +++++++++++++++++++++++++
arch/arm/kernel/kgdb_fiq_entry.S | 87 +++++++++++++++++++
arch/arm/mach-versatile/Makefile | 1 +
arch/arm/mach-versatile/kgdb_fiq.c | 55 ++++++++++++
9 files changed, 460 insertions(+), 168 deletions(-)
create mode 100644 arch/arm/kernel/kgdb_fiq.c
create mode 100644 arch/arm/kernel/kgdb_fiq_entry.S
create mode 100644 arch/arm/mach-versatile/kgdb_fiq.c
--
1.8.1.2
From: Anton Vorontsov <[email protected]>
If enabled, kernel will able to enter KGDB upon serial line activity on
UART ports.
Note that even with this patch and CONFIG_KGDB_FIQ is enabled, you still
need to pass kgdb_fiq.enable=1 kernel command line option, otherwise UART
will behave in a normal way.
By default UART0 is used, but this can be changed via kgdb_fiq.uart_num
kernel command line option.
Cc: Anton Vorontsov <[email protected]>
Cc: Russell King <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Jason Wessel <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Anton Vorontsov <[email protected]>
Signed-off-by: John Stultz <[email protected]>
---
arch/arm/Kconfig | 1 +
arch/arm/mach-versatile/Makefile | 1 +
arch/arm/mach-versatile/kgdb_fiq.c | 55 ++++++++++++++++++++++++++++++++++++++
3 files changed, 57 insertions(+)
create mode 100644 arch/arm/mach-versatile/kgdb_fiq.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 66a9076..9909af3 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -364,6 +364,7 @@ config ARCH_VERSATILE
select PLAT_VERSATILE_CLCD
select PLAT_VERSATILE_CLOCK
select VERSATILE_FPGA_IRQ
+ select ARCH_MIGHT_HAVE_KGDB_FIQ
help
This enables support for ARM Ltd Versatile board.
diff --git a/arch/arm/mach-versatile/Makefile b/arch/arm/mach-versatile/Makefile
index 81fa3fe..bfd761f 100644
--- a/arch/arm/mach-versatile/Makefile
+++ b/arch/arm/mach-versatile/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_ARCH_VERSATILE_PB) += versatile_pb.o
obj-$(CONFIG_MACH_VERSATILE_AB) += versatile_ab.o
obj-$(CONFIG_MACH_VERSATILE_DT) += versatile_dt.o
obj-$(CONFIG_PCI) += pci.o
+obj-$(CONFIG_KGDB_FIQ) += kgdb_fiq.o
diff --git a/arch/arm/mach-versatile/kgdb_fiq.c b/arch/arm/mach-versatile/kgdb_fiq.c
new file mode 100644
index 0000000..dd92e40
--- /dev/null
+++ b/arch/arm/mach-versatile/kgdb_fiq.c
@@ -0,0 +1,55 @@
+/*
+ * KGDB FIQ board support
+ *
+ * Copyright 2012 Linaro Ltd.
+ * Anton Vorontsov <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kgdb.h>
+#include <mach/hardware.h>
+#include <mach/platform.h>
+#include <asm/hardware/vic.h>
+
+static void *kgdb_irq_base;
+
+static int kgdb_irq;
+module_param_named(uart_num, kgdb_irq, int, 0600);
+MODULE_PARM_DESC(uart_num, "UART<number> port to use for KGDB FIQ");
+
+static void kgdb_fiq_select(bool on)
+{
+ void __iomem *sel = kgdb_irq_base + VIC_INT_SELECT;
+ u32 msk = 1 << kgdb_irq;
+ u32 val;
+
+ pr_debug("rerouting VIC vector %d to %s\n", kgdb_irq,
+ on ? "FIQ" : "IRQ");
+
+ val = readl(sel);
+ val &= ~msk;
+ if (on)
+ val |= msk;
+ writel(val, sel);
+}
+
+static bool kgdb_is_fiq_rised(void)
+{
+ return readl(kgdb_irq_base + VIC_FIQ_STATUS) & (1 << kgdb_irq);
+}
+
+static int __init kgdb_fiq_init(void)
+{
+ kgdb_irq_base = __io_address(VERSATILE_VIC_BASE);
+ kgdb_irq += INT_UARTINT0;
+ WARN_ON(kgdb_irq > INT_UARTINT2);
+
+ return kgdb_register_fiq(kgdb_fiq_select, kgdb_is_fiq_rised);
+}
+console_initcall(kgdb_fiq_init);
--
1.8.1.2
From: Anton Vorontsov <[email protected]>
The FIQ debugger may be used to debug situations when the kernel stuck
in uninterruptable sections, e.g. the kernel infinitely loops or
deadlocked in an interrupt or with interrupts disabled.
By default KGDB FIQ is disabled in runtime, but can be enabled with
kgdb_fiq.enable=1 kernel command line option.
Cc: Anton Vorontsov <[email protected]>
Cc: Russell King <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Jason Wessel <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Anton Vorontsov <[email protected]>
Signed-off-by: John Stultz <[email protected]>
---
arch/arm/Kconfig | 18 ++++++
arch/arm/include/asm/kgdb.h | 7 +++
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/kgdb_fiq.c | 118 +++++++++++++++++++++++++++++++++++++++
arch/arm/kernel/kgdb_fiq_entry.S | 87 +++++++++++++++++++++++++++++
5 files changed, 231 insertions(+)
create mode 100644 arch/arm/kernel/kgdb_fiq.c
create mode 100644 arch/arm/kernel/kgdb_fiq_entry.S
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 1e31dac..66a9076 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -203,6 +203,24 @@ config GENERIC_ISA_DMA
config FIQ
bool
+config ARCH_MIGHT_HAVE_KGDB_FIQ
+ bool
+
+config KGDB_FIQ
+ bool "KGDB/KDB FIQ debugger"
+ depends on KGDB_KDB && ARCH_MIGHT_HAVE_KGDB_FIQ && !THUMB2_KERNEL
+ select FIQ
+ help
+ The FIQ debugger may be used to debug situations when the
+ kernel stuck in uninterruptable sections, e.g. the kernel
+ infinitely loops or deadlocked in an interrupt or with
+ interrupts disabled.
+
+ By default KGDB FIQ is disabled in runtime, but can be
+ enabled with kgdb_fiq.enable=1 kernel command line option.
+
+ If unsure, say N.
+
config NEED_RET_TO_USER
bool
diff --git a/arch/arm/include/asm/kgdb.h b/arch/arm/include/asm/kgdb.h
index 48066ce..75019984 100644
--- a/arch/arm/include/asm/kgdb.h
+++ b/arch/arm/include/asm/kgdb.h
@@ -11,6 +11,8 @@
#define __ARM_KGDB_H__
#include <linux/ptrace.h>
+#include <linux/linkage.h>
+#include <asm/exception.h>
/*
* GDB assumes that we're a user process being debugged, so
@@ -47,6 +49,11 @@ static inline void arch_kgdb_breakpoint(void)
extern void kgdb_handle_bus_error(void);
extern int kgdb_fault_expected;
+extern char kgdb_fiq_handler;
+extern char kgdb_fiq_handler_end;
+asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs);
+extern int __init kgdb_register_fiq(void (*mach_kgdb_enable_fiq)(bool on),
+ bool (*mach_is_kgdb_fiq)(void));
#endif /* !__ASSEMBLY__ */
/*
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 5f3338e..863d266 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -56,6 +56,7 @@ endif
obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o
obj-$(CONFIG_ARM_THUMBEE) += thumbee.o
obj-$(CONFIG_KGDB) += kgdb.o
+obj-$(CONFIG_KGDB_FIQ) += kgdb_fiq_entry.o kgdb_fiq.o
obj-$(CONFIG_ARM_UNWIND) += unwind.o
obj-$(CONFIG_HAVE_TCM) += tcm.o
obj-$(CONFIG_OF) += devtree.o
diff --git a/arch/arm/kernel/kgdb_fiq.c b/arch/arm/kernel/kgdb_fiq.c
new file mode 100644
index 0000000..bede9be
--- /dev/null
+++ b/arch/arm/kernel/kgdb_fiq.c
@@ -0,0 +1,118 @@
+/*
+ * KGDB FIQ
+ *
+ * Copyright 2010 Google, Inc.
+ * Arve Hjønnevåg <[email protected]>
+ * Colin Cross <[email protected]>
+ * Copyright 2012 Linaro Ltd.
+ * Anton Vorontsov <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/hardirq.h>
+#include <linux/atomic.h>
+#include <linux/kdb.h>
+#include <linux/kgdb.h>
+#include <asm/fiq.h>
+#include <asm/exception.h>
+
+static int kgdb_fiq_enabled;
+module_param_named(enable, kgdb_fiq_enabled, int, 0600);
+MODULE_PARM_DESC(enable, "set to 1 to enable FIQ KGDB");
+
+static bool (*is_kgdb_fiq)(void);
+static void (*kgdb_enable_fiq)(bool on);
+
+asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs)
+{
+ if (!is_kgdb_fiq())
+ return;
+ if (!kgdb_nmi_poll_knock())
+ return;
+
+ nmi_enter();
+ kgdb_handle_exception(1, 0, 0, regs);
+ nmi_exit();
+}
+
+static struct fiq_handler kgdb_fiq_desc = {
+ .name = "kgdb",
+};
+
+static long kgdb_fiq_setup_stack(void *info)
+{
+ struct pt_regs regs;
+
+ regs.ARM_sp = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER) +
+ THREAD_START_SP;
+ WARN_ON(!regs.ARM_sp);
+
+ set_fiq_regs(®s);
+ return 0;
+}
+
+/**
+ * kgdb_fiq_enable_nmi - Manage NMI-triggered entry to KGDB
+ * @on: Flag to either enable or disable an NMI
+ *
+ * This function manages NMIs that usually cause KGDB to enter. That is, not
+ * all NMIs should be enabled or disabled, but only those that issue
+ * kgdb_handle_exception().
+ *
+ * The call counts disable requests, and thus allows to nest disables. But
+ * trying to enable already enabled NMI is an error.
+ */
+static void kgdb_fiq_enable_nmi(bool on)
+{
+ static atomic_t cnt;
+ int ret;
+
+ ret = atomic_add_return(on ? 1 : -1, &cnt);
+ if (ret > 1 && on) {
+ /*
+ * There should be only one instance that calls this function
+ * in "enable, disable" order. All other users must call
+ * disable first, then enable. If not, something is wrong.
+ */
+ WARN_ON(1);
+ return;
+ }
+
+ kgdb_enable_fiq(ret > 0);
+}
+
+int __init kgdb_register_fiq(void (*mach_kgdb_enable_fiq)(bool on),
+ bool (*mach_is_kgdb_fiq)(void))
+{
+ int err;
+ int cpu;
+
+ if (!kgdb_fiq_enabled)
+ return -ENODEV;
+
+ kgdb_enable_fiq = mach_kgdb_enable_fiq;
+ is_kgdb_fiq = mach_is_kgdb_fiq;
+
+ err = claim_fiq(&kgdb_fiq_desc);
+ if (err) {
+ pr_warn("%s: unable to claim fiq", __func__);
+ return err;
+ }
+
+ for_each_possible_cpu(cpu)
+ work_on_cpu(cpu, kgdb_fiq_setup_stack, NULL);
+
+ set_fiq_handler(&kgdb_fiq_handler,
+ &kgdb_fiq_handler_end - &kgdb_fiq_handler);
+
+ arch_kgdb_ops.enable_nmi = kgdb_fiq_enable_nmi;
+ return 0;
+}
diff --git a/arch/arm/kernel/kgdb_fiq_entry.S b/arch/arm/kernel/kgdb_fiq_entry.S
new file mode 100644
index 0000000..d6becca
--- /dev/null
+++ b/arch/arm/kernel/kgdb_fiq_entry.S
@@ -0,0 +1,87 @@
+/*
+ * KGDB FIQ entry
+ *
+ * Copyright 1996,1997,1998 Russell King.
+ * Copyright 2012 Linaro Ltd.
+ * Anton Vorontsov <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/memory.h>
+#include <asm/unwind.h>
+#include "entry-header.S"
+
+ .text
+
+@ This is needed for usr_entry/alignment_trap
+.LCcralign:
+ .long cr_alignment
+.LCdohandle:
+ .long kgdb_fiq_do_handle
+
+ .macro fiq_handler
+ ldr r1, =.LCdohandle
+ mov r0, sp
+ adr lr, BSYM(9997f)
+ ldr pc, [r1]
+9997:
+ .endm
+
+ .align 5
+__fiq_svc:
+ svc_entry
+ fiq_handler
+ mov r0, sp
+ ldmib r0, {r1 - r14}
+ msr cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT
+ add r8, r0, #S_PC
+ ldr r9, [r0, #S_PSR]
+ msr spsr_cxsf, r9
+ ldr r0, [r0, #S_R0]
+ ldmia r8, {pc}^
+
+ UNWIND(.fnend )
+ENDPROC(__fiq_svc)
+ .ltorg
+
+ .align 5
+__fiq_usr:
+ usr_entry
+ kuser_cmpxchg_check
+ fiq_handler
+ get_thread_info tsk
+ mov why, #0
+ b ret_to_user_from_irq
+ UNWIND(.fnend )
+ENDPROC(__fiq_usr)
+ .ltorg
+
+ .global kgdb_fiq_handler
+kgdb_fiq_handler:
+
+ vector_stub fiq, FIQ_MODE, 4
+
+ .long __fiq_usr @ 0 (USR_26 / USR_32)
+ .long __fiq_svc @ 1 (FIQ_26 / FIQ_32)
+ .long __fiq_svc @ 2 (IRQ_26 / IRQ_32)
+ .long __fiq_svc @ 3 (SVC_26 / SVC_32)
+ .long __fiq_svc @ 4
+ .long __fiq_svc @ 5
+ .long __fiq_svc @ 6
+ .long __fiq_svc @ 7
+ .long __fiq_svc @ 8
+ .long __fiq_svc @ 9
+ .long __fiq_svc @ a
+ .long __fiq_svc @ b
+ .long __fiq_svc @ c
+ .long __fiq_svc @ d
+ .long __fiq_svc @ e
+ .long __fiq_svc @ f
+
+ .global kgdb_fiq_handler_end
+kgdb_fiq_handler_end:
--
1.8.1.2
From: Anton Vorontsov <[email protected]>
Just move the macros into header file as we would want to use them for
KGDB FIQ entry code.
The following macros were moved:
- svc_entry
- usr_entry
- kuser_cmpxchg_check
- vector_stub
To make kuser_cmpxchg_check actually work across different files, we
also have to make kuser_cmpxchg64_fixup global.
Cc: Anton Vorontsov <[email protected]>
Cc: Russell King <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Jason Wessel <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Anton Vorontsov <[email protected]>
Signed-off-by: John Stultz <[email protected]>
---
arch/arm/kernel/entry-armv.S | 169 +---------------------------------------
arch/arm/kernel/entry-header.S | 171 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 172 insertions(+), 168 deletions(-)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 582b405..35b19cd 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -136,57 +136,6 @@ common_invalid:
b bad_mode
ENDPROC(__und_invalid)
-/*
- * SVC mode handlers
- */
-
-#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5)
-#define SPFIX(code...) code
-#else
-#define SPFIX(code...)
-#endif
-
- .macro svc_entry, stack_hole=0
- UNWIND(.fnstart )
- UNWIND(.save {r0 - pc} )
- sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4)
-#ifdef CONFIG_THUMB2_KERNEL
- SPFIX( str r0, [sp] ) @ temporarily saved
- SPFIX( mov r0, sp )
- SPFIX( tst r0, #4 ) @ test original stack alignment
- SPFIX( ldr r0, [sp] ) @ restored
-#else
- SPFIX( tst sp, #4 )
-#endif
- SPFIX( subeq sp, sp, #4 )
- stmia sp, {r1 - r12}
-
- ldmia r0, {r3 - r5}
- add r7, sp, #S_SP - 4 @ here for interlock avoidance
- mov r6, #-1 @ "" "" "" ""
- add r2, sp, #(S_FRAME_SIZE + \stack_hole - 4)
- SPFIX( addeq r2, r2, #4 )
- str r3, [sp, #-4]! @ save the "real" r0 copied
- @ from the exception stack
-
- mov r3, lr
-
- @
- @ We are now ready to fill in the remaining blanks on the stack:
- @
- @ r2 - sp_svc
- @ r3 - lr_svc
- @ r4 - lr_<exception>, already fixed up for correct return/restart
- @ r5 - spsr_<exception>
- @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
- @
- stmia r7, {r2 - r6}
-
-#ifdef CONFIG_TRACE_IRQFLAGS
- bl trace_hardirqs_off
-#endif
- .endm
-
.align 5
__dabt_svc:
svc_entry
@@ -305,72 +254,7 @@ ENDPROC(__pabt_svc)
/*
* User mode handlers
- *
- * EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE
*/
-
-#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7)
-#error "sizeof(struct pt_regs) must be a multiple of 8"
-#endif
-
- .macro usr_entry
- UNWIND(.fnstart )
- UNWIND(.cantunwind ) @ don't unwind the user space
- sub sp, sp, #S_FRAME_SIZE
- ARM( stmib sp, {r1 - r12} )
- THUMB( stmia sp, {r0 - r12} )
-
- ldmia r0, {r3 - r5}
- add r0, sp, #S_PC @ here for interlock avoidance
- mov r6, #-1 @ "" "" "" ""
-
- str r3, [sp] @ save the "real" r0 copied
- @ from the exception stack
-
- @
- @ We are now ready to fill in the remaining blanks on the stack:
- @
- @ r4 - lr_<exception>, already fixed up for correct return/restart
- @ r5 - spsr_<exception>
- @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
- @
- @ Also, separately save sp_usr and lr_usr
- @
- stmia r0, {r4 - r6}
- ARM( stmdb r0, {sp, lr}^ )
- THUMB( store_user_sp_lr r0, r1, S_SP - S_PC )
-
- @
- @ Enable the alignment trap while in kernel mode
- @
- alignment_trap r0
-
- @
- @ Clear FP to mark the first stack frame
- @
- zero_fp
-
-#ifdef CONFIG_IRQSOFF_TRACER
- bl trace_hardirqs_off
-#endif
- ct_user_exit save = 0
- .endm
-
- .macro kuser_cmpxchg_check
-#if !defined(CONFIG_CPU_32v6K) && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
-#ifndef CONFIG_MMU
-#warning "NPTL on non MMU needs fixing"
-#else
- @ Make sure our user space atomic helper is restarted
- @ if it was interrupted in a critical region. Here we
- @ perform a quick test inline since it should be false
- @ 99.9999% of the time. The rest is done out of line.
- cmp r4, #TASK_SIZE
- blhs kuser_cmpxchg64_fixup
-#endif
-#endif
- .endm
-
.align 5
__dabt_usr:
usr_entry
@@ -803,6 +687,7 @@ __kuser_cmpxchg64: @ 0xffff0f60
ldmfd sp!, {r4, r5, r6, pc}
.text
+ .global kuser_cmpxchg64_fixup
kuser_cmpxchg64_fixup:
@ Called from kuser_cmpxchg_fixup.
@ r4 = address of interrupted insn (must be preserved).
@@ -933,58 +818,6 @@ __kuser_helper_end:
THUMB( .thumb )
-/*
- * Vector stubs.
- *
- * This code is copied to 0xffff0200 so we can use branches in the
- * vectors, rather than ldr's. Note that this code must not
- * exceed 0x300 bytes.
- *
- * Common stub entry macro:
- * Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC
- *
- * SP points to a minimal amount of processor-private memory, the address
- * of which is copied into r0 for the mode specific abort handler.
- */
- .macro vector_stub, name, mode, correction=0
- .align 5
-
-vector_\name:
- .if \correction
- sub lr, lr, #\correction
- .endif
-
- @
- @ Save r0, lr_<exception> (parent PC) and spsr_<exception>
- @ (parent CPSR)
- @
- stmia sp, {r0, lr} @ save r0, lr
- mrs lr, spsr
- str lr, [sp, #8] @ save spsr
-
- @
- @ Prepare for SVC32 mode. IRQs remain disabled.
- @
- mrs r0, cpsr
- eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE)
- msr spsr_cxsf, r0
-
- @
- @ the branch table must immediately follow this code
- @
- and lr, lr, #0x0f
- THUMB( adr r0, 1f )
- THUMB( ldr lr, [r0, lr, lsl #2] )
- mov r0, sp
- ARM( ldr lr, [pc, lr, lsl #2] )
- movs pc, lr @ branch to handler in SVC mode
-ENDPROC(vector_\name)
-
- .align 2
- @ handler addresses follow this label
-1:
- .endm
-
.globl __stubs_start
__stubs_start:
/*
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 160f337..41de38b 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -73,6 +73,109 @@
msr cpsr_c, \rtemp @ switch back to the SVC mode
.endm
+/*
+ * Vector stubs.
+ *
+ * This code is copied to 0xffff0200 so we can use branches in the
+ * vectors, rather than ldr's. Note that this code must not
+ * exceed 0x300 bytes.
+ *
+ * Common stub entry macro:
+ * Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC
+ *
+ * SP points to a minimal amount of processor-private memory, the address
+ * of which is copied into r0 for the mode specific abort handler.
+ */
+ .macro vector_stub, name, mode, correction=0
+ .align 5
+
+vector_\name:
+ .if \correction
+ sub lr, lr, #\correction
+ .endif
+
+ @
+ @ Save r0, lr_<exception> (parent PC) and spsr_<exception>
+ @ (parent CPSR)
+ @
+ stmia sp, {r0, lr} @ save r0, lr
+ mrs lr, spsr
+ str lr, [sp, #8] @ save spsr
+
+ @
+ @ Prepare for SVC32 mode. IRQs remain disabled.
+ @
+ mrs r0, cpsr
+ eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE)
+ msr spsr_cxsf, r0
+
+ @
+ @ the branch table must immediately follow this code
+ @
+ and lr, lr, #0x0f
+ THUMB( adr r0, 1f )
+ THUMB( ldr lr, [r0, lr, lsl #2] )
+ mov r0, sp
+ ARM( ldr lr, [pc, lr, lsl #2] )
+ movs pc, lr @ branch to handler in SVC mode
+ENDPROC(vector_\name)
+
+ .align 2
+ @ handler addresses follow this label
+1:
+ .endm
+
+/*
+ * SVC mode handlers
+ */
+
+#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5)
+#define SPFIX(code...) code
+#else
+#define SPFIX(code...)
+#endif
+
+ .macro svc_entry, stack_hole=0
+ UNWIND(.fnstart )
+ UNWIND(.save {r0 - pc} )
+ sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4)
+#ifdef CONFIG_THUMB2_KERNEL
+ SPFIX( str r0, [sp] ) @ temporarily saved
+ SPFIX( mov r0, sp )
+ SPFIX( tst r0, #4 ) @ test original stack alignment
+ SPFIX( ldr r0, [sp] ) @ restored
+#else
+ SPFIX( tst sp, #4 )
+#endif
+ SPFIX( subeq sp, sp, #4 )
+ stmia sp, {r1 - r12}
+
+ ldmia r0, {r3 - r5}
+ add r7, sp, #S_SP - 4 @ here for interlock avoidance
+ mov r6, #-1 @ "" "" "" ""
+ add r2, sp, #(S_FRAME_SIZE + \stack_hole - 4)
+ SPFIX( addeq r2, r2, #4 )
+ str r3, [sp, #-4]! @ save the "real" r0 copied
+ @ from the exception stack
+
+ mov r3, lr
+
+ @
+ @ We are now ready to fill in the remaining blanks on the stack:
+ @
+ @ r2 - sp_svc
+ @ r3 - lr_svc
+ @ r4 - lr_<exception>, already fixed up for correct return/restart
+ @ r5 - spsr_<exception>
+ @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
+ @
+ stmia r7, {r2 - r6}
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+ bl trace_hardirqs_off
+#endif
+ .endm
+
#ifndef CONFIG_THUMB2_KERNEL
.macro svc_exit, rpsr, irq = 0
.if \irq != 0
@@ -226,6 +329,74 @@
.endm
/*
+ * User mode handlers
+ *
+ * EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE
+ */
+
+#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7)
+#error "sizeof(struct pt_regs) must be a multiple of 8"
+#endif
+
+ .macro usr_entry
+ UNWIND(.fnstart )
+ UNWIND(.cantunwind ) @ don't unwind the user space
+ sub sp, sp, #S_FRAME_SIZE
+ ARM( stmib sp, {r1 - r12} )
+ THUMB( stmia sp, {r0 - r12} )
+
+ ldmia r0, {r3 - r5}
+ add r0, sp, #S_PC @ here for interlock avoidance
+ mov r6, #-1 @ "" "" "" ""
+
+ str r3, [sp] @ save the "real" r0 copied
+ @ from the exception stack
+
+ @
+ @ We are now ready to fill in the remaining blanks on the stack:
+ @
+ @ r4 - lr_<exception>, already fixed up for correct return/restart
+ @ r5 - spsr_<exception>
+ @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
+ @
+ @ Also, separately save sp_usr and lr_usr
+ @
+ stmia r0, {r4 - r6}
+ ARM( stmdb r0, {sp, lr}^ )
+ THUMB( store_user_sp_lr r0, r1, S_SP - S_PC )
+
+ @
+ @ Enable the alignment trap while in kernel mode
+ @
+ alignment_trap r0
+
+ @
+ @ Clear FP to mark the first stack frame
+ @
+ zero_fp
+
+#ifdef CONFIG_IRQSOFF_TRACER
+ bl trace_hardirqs_off
+#endif
+ ct_user_exit save = 0
+ .endm
+
+ .macro kuser_cmpxchg_check
+#if !defined(CONFIG_CPU_32v6K) && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
+#ifndef CONFIG_MMU
+#warning "NPTL on non MMU needs fixing"
+#else
+ @ Make sure our user space atomic helper is restarted
+ @ if it was interrupted in a critical region. Here we
+ @ perform a quick test inline since it should be false
+ @ 99.9999% of the time. The rest is done out of line.
+ cmp r4, #TASK_SIZE
+ blhs kuser_cmpxchg64_fixup
+#endif
+#endif
+ .endm
+
+/*
* These are the registers used in the syscall handler, and allow us to
* have in theory up to 7 arguments to a function - r0 to r6.
*
--
1.8.1.2
Dear John Stultz,
On Thu, 9 May 2013 17:10:51 -0700, John Stultz wrote:
> +static void kgdb_fiq_select(bool on)
> +{
> + void __iomem *sel = kgdb_irq_base + VIC_INT_SELECT;
> + u32 msk = 1 << kgdb_irq;
> + u32 val;
> +
> + pr_debug("rerouting VIC vector %d to %s\n", kgdb_irq,
> + on ? "FIQ" : "IRQ");
> +
> + val = readl(sel);
> + val &= ~msk;
> + if (on)
> + val |= msk;
> + writel(val, sel);
> +}
> +
> +static bool kgdb_is_fiq_rised(void)
Shouldn't this function be kgdb_is_fiq_raised() ?
> +{
> + return readl(kgdb_irq_base + VIC_FIQ_STATUS) & (1 << kgdb_irq);
> +}
> +
> +static int __init kgdb_fiq_init(void)
> +{
> + kgdb_irq_base = __io_address(VERSATILE_VIC_BASE);
> + kgdb_irq += INT_UARTINT0;
> + WARN_ON(kgdb_irq > INT_UARTINT2);
> +
> + return kgdb_register_fiq(kgdb_fiq_select, kgdb_is_fiq_rised);
> +}
> +console_initcall(kgdb_fiq_init);
Also, this code that uses hardcoded addresses and IRQ numbers doesn't
seem to play really well with the DT. I was considering toying around
with this thing on the mach-mvebu platform, but don't have those
hardcoded addresses and IRQs, and the register offsets of the IRQ
controller driver are not exposed in an header file. Shouldn't IRQ
controller driver be exposing a the fiq_select() functionality instead?
Like a new flag for irq_chip->irq_set_type(), or a completely new hook
irq_chip->irq_set_mode() or something like that?
Best regards,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
Thanks a lot for the review, Thomas!
On Fri, May 10, 2013 at 04:17:10PM +0200, Thomas Petazzoni wrote:
[...]
> > +{
> > + return readl(kgdb_irq_base + VIC_FIQ_STATUS) & (1 << kgdb_irq);
> > +}
> > +
> > +static int __init kgdb_fiq_init(void)
> > +{
> > + kgdb_irq_base = __io_address(VERSATILE_VIC_BASE);
> > + kgdb_irq += INT_UARTINT0;
> > + WARN_ON(kgdb_irq > INT_UARTINT2);
> > +
> > + return kgdb_register_fiq(kgdb_fiq_select, kgdb_is_fiq_rised);
> > +}
> > +console_initcall(kgdb_fiq_init);
>
> Also, this code that uses hardcoded addresses and IRQ numbers doesn't
> seem to play really well with the DT. I was considering toying around
> with this thing on the mach-mvebu platform, but don't have those
> hardcoded addresses and IRQs, and the register offsets of the IRQ
> controller driver are not exposed in an header file. Shouldn't IRQ
> controller driver be exposing a the fiq_select() functionality instead?
> Like a new flag for irq_chip->irq_set_type(), or a completely new hook
> irq_chip->irq_set_mode() or something like that?
FIQs are very specific to the platform, and I doubt that anyone will be
happy in exposing this kind of knowledge to the generic subsystem.
Moreover, Russell King once said that we should better detach IRQ stuff
from FIQs altogether. Thing is, FIQs are not going through the generic IRQ
code flow, so there is actually very little point in managing them thru
the generic IRQ subsystem.
What seems more plausible is making a "FIQ subsystem", and register each
IRQ controller that can redirect its sources to FIQ with that new
subsystem. But the "subsystem" isn't there, and even doing some cleanups
in this core stuff takes forever to review/make decision. :) Plus, writing
it for this small thing seems like a bit of overhead.
And if you take a closer look at this patch, it actually does not use IRQ
numbers with the IRQ subsystem. Instead, it bypasses the whole thing and
writes to the VIC registers directly.
So, for your case (if you want to use FIQ debugger on your board), I would
suggest doing the same. At least until we figure out how to do these ten
lines of board-specific code better (ideas/hints are welcome! :)
Thanks!
Anton