diff options
| author | Jiri Olsa <jolsa@kernel.org> | 2026-01-26 22:18:32 +0100 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2026-01-30 13:40:08 -0800 |
| commit | 8bc11700e0d23d4fdb7d8d5a73b2e95de427cabc (patch) | |
| tree | 7af86da6987989782fc1535c7edca5449cf86c71 /arch | |
| parent | cd77618c418254b827f2a807b4c27b97088fdb52 (diff) | |
x86/fgraph: Fix return_to_handler regs.rsp value
The previous change (Fixes commit) messed up the rsp register value,
which is wrong because it's already adjusted with FRAME_SIZE, we need
the original rsp value.
This change does not affect fprobe current kernel unwind, the !perf_hw_regs
path perf_callchain_kernel:
if (perf_hw_regs(regs)) {
if (perf_callchain_store(entry, regs->ip))
return;
unwind_start(&state, current, regs, NULL);
} else {
unwind_start(&state, current, NULL, (void *)regs->sp);
}
which uses pt_regs.sp as first_frame boundary (FRAME_SIZE shift makes
no difference, unwind stil stops at the right frame).
This change fixes the other path when we want to unwind directly from
pt_regs sp/fp/ip state, which is coming in following change.
Fixes: 20a0bc10272f ("x86/fgraph,bpf: Fix stack ORC unwind from kprobe_multi return probe")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/bpf/20260126211837.472802-2-jolsa@kernel.org
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/ftrace_64.S | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S index a132608265f6..62c1c93aa1c6 100644 --- a/arch/x86/kernel/ftrace_64.S +++ b/arch/x86/kernel/ftrace_64.S @@ -364,6 +364,9 @@ SYM_CODE_START(return_to_handler) UNWIND_HINT_UNDEFINED ANNOTATE_NOENDBR + /* Store original rsp for pt_regs.sp value. */ + movq %rsp, %rdi + /* Restore return_to_handler value that got eaten by previous ret instruction. */ subq $8, %rsp UNWIND_HINT_FUNC @@ -374,7 +377,7 @@ SYM_CODE_START(return_to_handler) movq %rax, RAX(%rsp) movq %rdx, RDX(%rsp) movq %rbp, RBP(%rsp) - movq %rsp, RSP(%rsp) + movq %rdi, RSP(%rsp) movq %rsp, %rdi call ftrace_return_to_handler |