From: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> commit fd3dc56253acbe9c641a66d312d8393cd55eb04c upstream. 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-0coQ3vLg@xxxxxxxxxxxxxx/ Link: https://lore.kernel.org/linux-trace-kernel/20221209105247.01d4e51d@xxxxxxxxxxxxxxxxxx Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: "x86@xxxxxxxxxx" <x86@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Fixes: 768ae4406a5c ("x86/ftrace: Use text_poke()") Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/ftrace.c | 2 ++ 1 file changed, 2 insertions(+) --- 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; } }
