This series mainly updates the ARM stack trace code to use the newer and
simpler arch_stack_walk() interface (see patches 3 and 4). Two issues
were fixed before that (see patches 1 and 2).
v3 RESEND notes:
Rebase to v6.0-rc1.
It's been a month since I sent the v3. Linus told me I needed to add the
patch to Russell's patch tracker myself, rebase to v6.0-rc1 before that.
Thanks Linus for the tip!
Since commit af6f23b88e95 ("ARM/dma-mapping: use the generic versions of
dma_to_phys/phys_to_dma by default") and commit ae626eb97376
("ARM/dma-mapping: use dma-direct unconditionally") modified
arch/arm/Kconfig, there is a minor conflict with patch 4 when rebase.
v3: https://lore.kernel.org/lkml/[email protected]/
- According to the discussion with Linus and Russell in v1:
- Add a comment about "regs[1]" in patch 2, and remove the
unnecessary ternary operator in the initialization of
"frame->ex_frame".
- Remove the patch "ARM: stacktrace: Allow stack trace saving for
non-current tasks", and keep the check for not being able to
unwind non-current tasks (including tasks running on other CPUs)
when CONFIG_SMP=y in patch 4.
- Rebase to linux-5.19-rc8.
v2: https://lore.kernel.org/lkml/[email protected]/
- As suggested by Mark, the commit logs for patch 4 and 5 were
refined for easy review.
v1: https://lore.kernel.org/lkml/[email protected]/
Li Huafei (4):
ARM: stacktrace: Skip frame pointer boundary check for
call_with_stack()
ARM: stacktrace: Avoid duplicate saving of exception PC value
ARM: stacktrace: Make stack walk callback consistent with generic code
ARM: stacktrace: Convert stacktrace to generic ARCH_STACKWALK
arch/arm/Kconfig | 1 +
arch/arm/include/asm/stacktrace.h | 8 +-
arch/arm/kernel/perf_callchain.c | 9 +-
arch/arm/kernel/return_address.c | 9 +-
arch/arm/kernel/stacktrace.c | 191 ++++++++++++++----------------
arch/arm/lib/call_with_stack.S | 2 +
6 files changed, 110 insertions(+), 110 deletions(-)
--
2.17.1
As with the generic arch_stack_walk() code the ARM stack walk code takes
a callback that is called per stack frame. Currently the ARM code always
passes a struct stackframe to the callback and the generic code just
passes the pc, however none of the users ever reference anything in the
struct other than the pc value. The ARM code also uses a return type of
int while the generic code uses a return type of bool though in both
cases the return value is a boolean value and the sense is inverted
between the two.
In order to reduce code duplication when ARM is converted to use
arch_stack_walk() change the signature and return sense of the ARM
specific callback to match that of the generic code.
Signed-off-by: Li Huafei <[email protected]>
Reviewed-by: Mark Brown <[email protected]>
Reviewed-by: Linus Waleij <[email protected]>
---
arch/arm/include/asm/stacktrace.h | 2 +-
arch/arm/kernel/perf_callchain.c | 9 ++++-----
arch/arm/kernel/return_address.c | 8 ++++----
arch/arm/kernel/stacktrace.c | 13 ++++++-------
4 files changed, 15 insertions(+), 17 deletions(-)
diff --git a/arch/arm/include/asm/stacktrace.h b/arch/arm/include/asm/stacktrace.h
index 39be2d1aa27b..7269d1e13449 100644
--- a/arch/arm/include/asm/stacktrace.h
+++ b/arch/arm/include/asm/stacktrace.h
@@ -44,7 +44,7 @@ void arm_get_current_stackframe(struct pt_regs *regs, struct stackframe *frame)
extern int unwind_frame(struct stackframe *frame);
extern void walk_stackframe(struct stackframe *frame,
- int (*fn)(struct stackframe *, void *), void *data);
+ bool (*fn)(void *, unsigned long), void *data);
extern void dump_mem(const char *lvl, const char *str, unsigned long bottom,
unsigned long top);
diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c
index bc6b246ab55e..7147edbe56c6 100644
--- a/arch/arm/kernel/perf_callchain.c
+++ b/arch/arm/kernel/perf_callchain.c
@@ -81,13 +81,12 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
* whist unwinding the stackframe and is like a subroutine return so we use
* the PC.
*/
-static int
-callchain_trace(struct stackframe *fr,
- void *data)
+static bool
+callchain_trace(void *data, unsigned long pc)
{
struct perf_callchain_entry_ctx *entry = data;
- perf_callchain_store(entry, fr->pc);
- return 0;
+ perf_callchain_store(entry, pc);
+ return true;
}
void
diff --git a/arch/arm/kernel/return_address.c b/arch/arm/kernel/return_address.c
index 38f1ea9c724d..ac15db66df4c 100644
--- a/arch/arm/kernel/return_address.c
+++ b/arch/arm/kernel/return_address.c
@@ -16,17 +16,17 @@ struct return_address_data {
void *addr;
};
-static int save_return_addr(struct stackframe *frame, void *d)
+static bool save_return_addr(void *d, unsigned long pc)
{
struct return_address_data *data = d;
if (!data->level) {
- data->addr = (void *)frame->pc;
+ data->addr = (void *)pc;
- return 1;
+ return false;
} else {
--data->level;
- return 0;
+ return true;
}
}
diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index 85443b5d1922..d05968bc7812 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -127,12 +127,12 @@ int notrace unwind_frame(struct stackframe *frame)
#endif
void notrace walk_stackframe(struct stackframe *frame,
- int (*fn)(struct stackframe *, void *), void *data)
+ bool (*fn)(void *, unsigned long), void *data)
{
while (1) {
int ret;
- if (fn(frame, data))
+ if (!fn(data, frame->pc))
break;
ret = unwind_frame(frame);
if (ret < 0)
@@ -148,21 +148,20 @@ struct stack_trace_data {
unsigned int skip;
};
-static int save_trace(struct stackframe *frame, void *d)
+static bool save_trace(void *d, unsigned long addr)
{
struct stack_trace_data *data = d;
struct stack_trace *trace = data->trace;
- unsigned long addr = frame->pc;
if (data->no_sched_functions && in_sched_functions(addr))
- return 0;
+ return true;
if (data->skip) {
data->skip--;
- return 0;
+ return true;
}
trace->entries[trace->nr_entries++] = addr;
- return trace->nr_entries >= trace->max_entries;
+ return trace->nr_entries < trace->max_entries;
}
/* This must be noinline to so that our skip calculation works correctly */
--
2.17.1
Because an exception stack frame is not created in the exception entry,
save_trace() does special handling for the exception PC, but this is
only needed when CONFIG_FRAME_POINTER_UNWIND=y. When
CONFIG_ARM_UNWIND=y, unwind annotations have been added to the exception
entry and save_trace() will repeatedly save the exception PC:
[0x7f000090] hrtimer_hander+0x8/0x10 [hrtimer]
[0x8019ec50] __hrtimer_run_queues+0x18c/0x394
[0x8019f760] hrtimer_run_queues+0xbc/0xd0
[0x8019def0] update_process_times+0x34/0x80
[0x801ad2a4] tick_periodic+0x48/0xd0
[0x801ad3dc] tick_handle_periodic+0x1c/0x7c
[0x8010f2e0] twd_handler+0x30/0x40
[0x80177620] handle_percpu_devid_irq+0xa0/0x23c
[0x801718d0] generic_handle_domain_irq+0x24/0x34
[0x80502d28] gic_handle_irq+0x74/0x88
[0x8085817c] generic_handle_arch_irq+0x58/0x78
[0x80100ba8] __irq_svc+0x88/0xc8
[0x80108114] arch_cpu_idle+0x38/0x3c
[0x80108114] arch_cpu_idle+0x38/0x3c <==== duplicate saved exception PC
[0x80861bf8] default_idle_call+0x38/0x130
[0x8015d5cc] do_idle+0x150/0x214
[0x8015d978] cpu_startup_entry+0x18/0x1c
[0x808589c0] rest_init+0xd8/0xdc
[0x80c00a44] arch_post_acpi_subsys_init+0x0/0x8
We can move the special handling of the exception PC in save_trace() to
the unwind_frame() of the frame pointer unwinder.
Signed-off-by: Li Huafei <[email protected]>
Reviewed-by: Linus Waleij <[email protected]>
---
arch/arm/include/asm/stacktrace.h | 6 +++++
arch/arm/kernel/return_address.c | 1 +
arch/arm/kernel/stacktrace.c | 44 +++++++++++++++++++++----------
3 files changed, 37 insertions(+), 14 deletions(-)
diff --git a/arch/arm/include/asm/stacktrace.h b/arch/arm/include/asm/stacktrace.h
index 3e78f921b8b2..39be2d1aa27b 100644
--- a/arch/arm/include/asm/stacktrace.h
+++ b/arch/arm/include/asm/stacktrace.h
@@ -21,6 +21,9 @@ struct stackframe {
struct llist_node *kr_cur;
struct task_struct *tsk;
#endif
+#ifdef CONFIG_UNWINDER_FRAME_POINTER
+ bool ex_frame;
+#endif
};
static __always_inline
@@ -34,6 +37,9 @@ void arm_get_current_stackframe(struct pt_regs *regs, struct stackframe *frame)
frame->kr_cur = NULL;
frame->tsk = current;
#endif
+#ifdef CONFIG_UNWINDER_FRAME_POINTER
+ frame->ex_frame = in_entry_text(frame->pc);
+#endif
}
extern int unwind_frame(struct stackframe *frame);
diff --git a/arch/arm/kernel/return_address.c b/arch/arm/kernel/return_address.c
index 8aac1e10b117..38f1ea9c724d 100644
--- a/arch/arm/kernel/return_address.c
+++ b/arch/arm/kernel/return_address.c
@@ -47,6 +47,7 @@ void *return_address(unsigned int level)
frame.kr_cur = NULL;
frame.tsk = current;
#endif
+ frame.ex_frame = false;
walk_stackframe(&frame, save_return_addr, &data);
diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index af87040b0353..85443b5d1922 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -82,6 +82,27 @@ int notrace unwind_frame(struct stackframe *frame)
if (frame_pointer_check(frame))
return -EINVAL;
+ /*
+ * When we unwind through an exception stack, include the saved PC
+ * value into the stack trace.
+ */
+ if (frame->ex_frame) {
+ struct pt_regs *regs = (struct pt_regs *)frame->sp;
+
+ /*
+ * We check that 'regs + sizeof(struct pt_regs)' (that is,
+ * ®s[1]) does not exceed the bottom of the stack to avoid
+ * accessing data outside the task's stack. This may happen
+ * when frame->ex_frame is a false positive.
+ */
+ if ((unsigned long)®s[1] > ALIGN(frame->sp, THREAD_SIZE))
+ return -EINVAL;
+
+ frame->pc = regs->ARM_pc;
+ frame->ex_frame = false;
+ return 0;
+ }
+
/* restore the registers from the stack frame */
#ifdef CONFIG_CC_IS_CLANG
frame->sp = frame->fp;
@@ -98,6 +119,9 @@ int notrace unwind_frame(struct stackframe *frame)
(void *)frame->fp, &frame->kr_cur);
#endif
+ if (in_entry_text(frame->pc))
+ frame->ex_frame = true;
+
return 0;
}
#endif
@@ -128,7 +152,6 @@ static int save_trace(struct stackframe *frame, void *d)
{
struct stack_trace_data *data = d;
struct stack_trace *trace = data->trace;
- struct pt_regs *regs;
unsigned long addr = frame->pc;
if (data->no_sched_functions && in_sched_functions(addr))
@@ -139,19 +162,6 @@ static int save_trace(struct stackframe *frame, void *d)
}
trace->entries[trace->nr_entries++] = addr;
-
- if (trace->nr_entries >= trace->max_entries)
- return 1;
-
- if (!in_entry_text(frame->pc))
- return 0;
-
- regs = (struct pt_regs *)frame->sp;
- if ((unsigned long)®s[1] > ALIGN(frame->sp, THREAD_SIZE))
- return 0;
-
- trace->entries[trace->nr_entries++] = regs->ARM_pc;
-
return trace->nr_entries >= trace->max_entries;
}
@@ -193,6 +203,9 @@ static noinline void __save_stack_trace(struct task_struct *tsk,
frame.kr_cur = NULL;
frame.tsk = tsk;
#endif
+#ifdef CONFIG_UNWINDER_FRAME_POINTER
+ frame.ex_frame = false;
+#endif
walk_stackframe(&frame, save_trace, &data);
}
@@ -214,6 +227,9 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
frame.kr_cur = NULL;
frame.tsk = current;
#endif
+#ifdef CONFIG_UNWINDER_FRAME_POINTER
+ frame.ex_frame = in_entry_text(frame.pc);
+#endif
walk_stackframe(&frame, save_trace, &data);
}
--
2.17.1