From: "Madhavan T. Venkataraman" <madvenka@xxxxxxxxxxxxxxxxxxx>
Currently, arch_stack_walk() calls start_backtrace() and walk_stackframe()
separately. There is no need to do that. Instead, call start_backtrace()
from within walk_stackframe(). In other words, walk_stackframe() is the only
unwind function a consumer needs to call.
Currently, the only consumer is arch_stack_walk(). In the future,
arch_stack_walk_reliable() will be another consumer.
Currently, there is a check for a NULL task in unwind_frame(). It is not
needed since all current consumers pass a non-NULL task.
Use struct stackframe only within the unwind functions.
Signed-off-by: Madhavan T. Venkataraman <madvenka@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/stacktrace.c | 41 ++++++++++++++++++----------------
1 file changed, 22 insertions(+), 19 deletions(-)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 0fb58fed54cb..7217c4f63ef7 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -69,9 +69,6 @@ static int notrace unwind_frame(struct task_struct *tsk,
unsigned long fp = frame->fp;
struct stack_info info;
- if (!tsk)
- tsk = current;
-
/* Final frame; nothing to unwind */
if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)
return -ENOENT;
@@ -143,15 +140,19 @@ static int notrace unwind_frame(struct task_struct *tsk,
NOKPROBE_SYMBOL(unwind_frame);
static void notrace walk_stackframe(struct task_struct *tsk,
- struct stackframe *frame,
+ unsigned long fp, unsigned long pc,
bool (*fn)(void *, unsigned long), void *data)
{
+ struct stackframe frame;
+
+ start_backtrace(&frame, fp, pc);
+
while (1) {
int ret;
- if (!fn(data, frame->pc))
+ if (!fn(data, frame.pc))
break;
- ret = unwind_frame(tsk, frame);
+ ret = unwind_frame(tsk, &frame);
if (ret < 0)
break;
}
@@ -195,17 +196,19 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
void *cookie, struct task_struct *task,
struct pt_regs *regs)
{
- struct stackframe frame;
-
- if (regs)
- start_backtrace(&frame, regs->regs[29], regs->pc);
- else if (task == current)
- start_backtrace(&frame,
- (unsigned long)__builtin_frame_address(1),
- (unsigned long)__builtin_return_address(0));
- else
- start_backtrace(&frame, thread_saved_fp(task),
- thread_saved_pc(task));
-
- walk_stackframe(task, &frame, consume_entry, cookie);
+ unsigned long fp, pc;
+
+ if (regs) {
+ fp = regs->regs[29];
+ pc = regs->pc;
+ } else if (task == current) {
+ /* Skip arch_stack_walk() in the stack trace. */
+ fp = (unsigned long)__builtin_frame_address(1);
+ pc = (unsigned long)__builtin_return_address(0);
+ } else {
+ /* Caller guarantees that the task is not running. */
+ fp = thread_saved_fp(task);
+ pc = thread_saved_pc(task);
+ }
+ walk_stackframe(task, fp, pc, consume_entry, cookie);
}
--
2.25.1
