From: "Steven Rostedt (Google)" rostedt@goodmis.org

After someone reported a bug report with a failed modification due to the expected value not matching what was found, it came to my attention that the ftrace_expected is no longer set when that happens. This makes for debugging the issue a bit more difficult.

Set ftrace_expected to the expected code before calling ftrace_bug, so that it shows what was expected and why it failed.

Link: https://lore.kernel.org/all/CA+wXwBQ-VhK+hpBtYtyZP-NiX4g8fqRRWithFOHQW-0coQ3... Link: https://lore.kernel.org/linux-trace-kernel/20221209105247.01d4e51d@gandalf.l...

Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Andrew Morton akpm@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: "x86@kernel.org" x86@kernel.org Cc: Borislav Petkov bp@alien8.de Cc: Ingo Molnar mingo@kernel.org Cc: stable@vger.kernel.org Fixes: 768ae4406a5c ("x86/ftrace: Use text_poke()") Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org --- arch/x86/kernel/ftrace.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index bd165004776d..e07234ec7e23 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -217,7 +217,9 @@ void ftrace_replace_code(int enable)

ret = ftrace_verify_code(rec->ip, old); if (ret) { + ftrace_expected = old; ftrace_bug(ret, rec); + ftrace_expected = NULL; return; } }