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| author | Jiri Olsa <jolsa@kernel.org> | 2025-11-05 00:54:03 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2025-11-06 04:05:19 +0300 |
| commit | 20a0bc10272fa17a44fc857c31574a8306f60d20 (patch) | |
| tree | 8d74704270a5258a2a5300a6df39ba6c98212877 /include/linux | |
| parent | 6d08340d1e354787d6c65a8c3cdd4d41ffb8a5ed (diff) | |
| download | linux-20a0bc10272fa17a44fc857c31574a8306f60d20.tar.xz | |
x86/fgraph,bpf: Fix stack ORC unwind from kprobe_multi return probe
Currently we don't get stack trace via ORC unwinder on top of fgraph exit
handler. We can see that when generating stacktrace from kretprobe_multi
bpf program which is based on fprobe/fgraph.
The reason is that the ORC unwind code won't get pass the return_to_handler
callback installed by fgraph return probe machinery.
Solving this by creating stack frame in return_to_handler expected by
ftrace_graph_ret_addr function to recover original return address and
continue with the unwind.
Also updating the pt_regs data with cs/flags/rsp which are needed for
successful stack retrieval from ebpf bpf_get_stackid helper.
- in get_perf_callchain we check user_mode(regs) so CS has to be set
- in perf_callchain_kernel we call perf_hw_regs(regs), so EFLAGS/FIXED
has to be unset
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20251104215405.168643-3-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/ftrace.h | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 7ded7df6e9b5..07f8c309e432 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -193,6 +193,10 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs #if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) || \ defined(CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS) +#ifndef arch_ftrace_partial_regs +#define arch_ftrace_partial_regs(regs) do {} while (0) +#endif + static __always_inline struct pt_regs * ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs) { @@ -202,7 +206,11 @@ ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs) * Since arch_ftrace_get_regs() will check some members and may return * NULL, we can not use it. */ - return &arch_ftrace_regs(fregs)->regs; + regs = &arch_ftrace_regs(fregs)->regs; + + /* Allow arch specific updates to regs. */ + arch_ftrace_partial_regs(regs); + return regs; } #endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS */ |