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[Backport v3.7-branch] arch: riscv: stacktrace: fix output without ra on the stack top #76755

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[Backport v3.7-branch] arch: riscv: stacktrace: fix output without ra on the stack top #76755

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58 changes: 46 additions & 12 deletions arch/riscv/core/stacktrace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -90,7 +90,10 @@ static bool in_stack_bound(uintptr_t addr, const struct k_thread *const thread,
static bool in_fatal_stack_bound(uintptr_t addr, const struct k_thread *const thread,
const struct arch_esf *esf)
{
if (!IS_ALIGNED(addr, sizeof(uintptr_t))) {
const uintptr_t align =
COND_CODE_1(CONFIG_FRAME_POINTER, (ARCH_STACK_PTR_ALIGN), (sizeof(uintptr_t)));

if (!IS_ALIGNED(addr, align)) {
return false;
}

Expand Down Expand Up @@ -134,22 +137,53 @@ static void walk_stackframe(stack_trace_callback_fn cb, void *cookie, const stru
ra = csf->ra;
}

for (int i = 0; (i < MAX_STACK_FRAMES) && vrfy(fp, thread, esf) && (fp > last_fp);) {
if (in_text_region(ra)) {
if (!cb(cookie, ra)) {
break;
}
/*
* Increment the iterator only if `ra` is within the text region to get the
* most out of it
*/
i++;
for (int i = 0; (i < MAX_STACK_FRAMES) && vrfy(fp, thread, esf) && (fp > last_fp); i++) {
if (in_text_region(ra) && !cb(cookie, ra)) {
break;
}
last_fp = fp;

/* Unwind to the previous frame */
frame = (struct stackframe *)fp - 1;
ra = frame->ra;

if ((i == 0) && (esf != NULL)) {
/* Print `esf->ra` if we are at the top of the stack */
if (in_text_region(esf->ra) && !cb(cookie, esf->ra)) {
break;
}
/**
* For the first stack frame, the `ra` is not stored in the frame if the
* preempted function doesn't call any other function, we can observe:
*
* .-------------.
* frame[0]->fp ---> | frame[0] fp |
* :-------------:
* frame[0]->ra ---> | frame[1] fp |
* | frame[1] ra |
* :~~~~~~~~~~~~~:
* | frame[N] fp |
*
* Instead of:
*
* .-------------.
* frame[0]->fp ---> | frame[0] fp |
* frame[0]->ra ---> | frame[1] ra |
* :-------------:
* | frame[1] fp |
* | frame[1] ra |
* :~~~~~~~~~~~~~:
* | frame[N] fp |
*
* Check if `frame->ra` actually points to a `fp`, and adjust accordingly
*/
if (vrfy(frame->ra, thread, esf)) {
fp = frame->ra;
frame = (struct stackframe *)fp;
}
}

fp = frame->fp;
ra = frame->ra;
}
}
#else /* !CONFIG_FRAME_POINTER */
Expand Down