path: root/arch/riscv
diff options
authorChen Huang <>2021-04-29 07:03:48 +0000
committerPalmer Dabbelt <>2021-05-22 18:59:20 -0700
commiteac2f3059e02382d91f8c887462083841d6ea2a3 (patch)
treeb2a5e92f2ee0853bd578038c348efaea5a825cb6 /arch/riscv
parent6efb943b8616ec53a5e444193dccf1af9ad627b5 (diff)
riscv: stacktrace: fix the riscv stacktrace when CONFIG_FRAME_POINTER enabled
As [1] and [2] said, the arch_stack_walk should not to trace itself, or it will leave the trace unexpectedly when called. The example is when we do "cat /sys/kernel/debug/page_owner", all pages' stack is the same. arch_stack_walk+0x18/0x20 stack_trace_save+0x40/0x60 register_dummy_stack+0x24/0x5e init_page_owner+0x2e So we use __builtin_frame_address(1) as the first frame to be walked. And mark the arch_stack_walk() noinline. We found that pr_cont will affact pages' stack whose task state is RUNNING when testing "echo t > /proc/sysrq-trigger". So move the place of pr_cont and mark the function dump_backtrace() noinline. Also we move the case when task == NULL into else branch, and test for it in "echo c > /proc/sysrq-trigger". [1] [2] Signed-off-by: Chen Huang <> Fixes: 5d8544e2d007 ("RISC-V: Generic library routines and assembly") Cc: Signed-off-by: Palmer Dabbelt <>
Diffstat (limited to 'arch/riscv')
1 files changed, 7 insertions, 7 deletions
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index 2b3e0cb90d78..bde85fc53357 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -27,10 +27,10 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
fp = frame_pointer(regs);
sp = user_stack_pointer(regs);
pc = instruction_pointer(regs);
- } else if (task == NULL || task == current) {
- fp = (unsigned long)__builtin_frame_address(0);
- sp = sp_in_global;
- pc = (unsigned long)walk_stackframe;
+ } else if (task == current) {
+ fp = (unsigned long)__builtin_frame_address(1);
+ sp = (unsigned long)__builtin_frame_address(0);
+ pc = (unsigned long)__builtin_return_address(0);
} else {
/* task blocked in __switch_to */
fp = task->thread.s[0];
@@ -106,15 +106,15 @@ static bool print_trace_address(void *arg, unsigned long pc)
return true;
-void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
+noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
const char *loglvl)
- pr_cont("%sCall Trace:\n", loglvl);
walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
+ pr_cont("%sCall Trace:\n", loglvl);
dump_backtrace(NULL, task, loglvl);
@@ -139,7 +139,7 @@ unsigned long get_wchan(struct task_struct *task)
-void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
+noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
struct task_struct *task, struct pt_regs *regs)
walk_stackframe(task, regs, consume_entry, cookie);