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authorLi Huafei <lihuafei1@huawei.com>2022-08-26 11:08:46 +0300
committerRussell King (Oracle) <rmk+kernel@armlinux.org.uk>2022-10-04 13:09:47 +0300
commit752ec621ef5c30777958cc5eb5f1cf394f7733f4 (patch)
tree949dee0e8a6519bfc707229fe6c7dccde1b548e8 /arch
parent5854e4d8530e6ed4c2532a71a6b0474e199d44dd (diff)
downloadlinux-752ec621ef5c30777958cc5eb5f1cf394f7733f4.tar.xz
ARM: 9234/1: stacktrace: Avoid duplicate saving of exception PC value
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 <lihuafei1@huawei.com> Reviewed-by: Linus Waleij <linus.walleij@linaro.org> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/include/asm/stacktrace.h6
-rw-r--r--arch/arm/kernel/return_address.c1
-rw-r--r--arch/arm/kernel/stacktrace.c44
3 files changed, 37 insertions, 14 deletions
diff --git a/arch/arm/include/asm/stacktrace.h b/arch/arm/include/asm/stacktrace.h
index dd19a46f781a..36b2ff44fcbb 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 @@ here:
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,
+ * &regs[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)&regs[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)&regs[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 @@ here:
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);
}