From: "Steven Rostedt (Google)" rostedt@goodmis.org
When a ftrace_bug happens (where ftrace fails to modify a location) it is helpful to have what was at that location as well as what was expected to be there.
But with the conversion to text_poke() the variable that assigns the expected for debugging was dropped. Unfortunately, I noticed this when I needed it. Add it back.
Link: https://lkml.kernel.org/r/20220726101851.069d2e70@gandalf.local.home
Cc: "x86@kernel.org" x86@kernel.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@kernel.org Cc: Borislav Petkov bp@alien8.de Cc: "H. Peter Anvin" hpa@zytor.com Cc: Andrew Morton akpm@linux-foundation.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 | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 5b4efc927d80..f5cdb5f675b3 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -91,6 +91,7 @@ static int ftrace_verify_code(unsigned long ip, const char *old_code)
/* Make sure it is what we expect it to be */ if (memcmp(cur_code, old_code, MCOUNT_INSN_SIZE) != 0) { + ftrace_expected = old_code; WARN_ON(1); return -EINVAL; }