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Rewrite how we read link register

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This commit is contained in:
Gregory LEOCADIE
2025-03-25 14:16:03 +01:00
parent 6eb27584fd
commit 4c341da1d2
2 changed files with 7 additions and 12 deletions
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7
src/aarch64/Gtrace.c
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@@ -412,7 +412,7 @@ tdep_trace (unw_cursor_t *cursor, void **buffer, int *size)
struct cursor *c = (struct cursor *) cursor;
struct dwarf_cursor *d = &c->dwarf;
unw_trace_cache_t *cache;
unw_word_t fp, sp, pc, cfa, lr;
unw_word_t fp, sp, pc, cfa, lr = 0;
int maxdepth = 0;
int depth = 0;
int ret;
@@ -433,11 +433,6 @@ tdep_trace (unw_cursor_t *cursor, void **buffer, int *size)
ACCESS_MEM_FAST(ret, 0, d, DWARF_GET_LOC(d->loc[UNW_AARCH64_X29]), fp);
assert(ret == 0);
/* In case of unwinding from ucontext_t, we can look at the link
register value. */
ACCESS_MEM_FAST(ret, 0, d, DWARF_GET_LOC(d->loc[UNW_AARCH64_X30]), lr);
assert(ret == 0);
/* Get frame cache. */
if (unlikely(! (cache = trace_cache_get())))
{

12
src/arm/Gtrace.c
View File

@@ -424,11 +424,6 @@ tdep_trace (unw_cursor_t *cursor, void **buffer, int *size)
ACCESS_MEM_FAST(ret, 0, d, DWARF_GET_LOC(d->loc[UNW_ARM_R7]), r7);
assert(ret == 0);
/* In case of unwinding from ucontext_t, we can look at the link
register value. On ARM, the register R14 acts as the link register */
ACCESS_MEM_FAST(ret, 0, d, DWARF_GET_LOC(d->loc[UNW_ARM_R14]), lr);
assert(ret == 0);
/* Get frame cache. */
if (unlikely(! (cache = trace_cache_get())))
{
@@ -488,8 +483,13 @@ tdep_trace (unw_cursor_t *cursor, void **buffer, int *size)
/* Advance standard traceable frame. */
cfa = (f->cfa_reg_sp ? sp : r7) + f->cfa_reg_offset;
if (likely(f->lr_cfa_offset != -1))
{
ACCESS_MEM_FAST(ret, c->validate, d, cfa + f->lr_cfa_offset, pc);
else if (lr != 0)
}
// lr might have been set by the previous frame (sigreturn)
// but we might get here directly (uwn_backtrace2 for ex) and lr was not set.
// In that case, try reading from the Link Register (X30)
else if (lr != 0 || dwarf_get (d, d->loc[UNW_ARM_R14], &lr) >= 0)
{
/* Use the saved link register as the new pc. */
Debug(4, "use link register value 0x%lx as the new pc\n", lr);