From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Date: Fri, 9 Dec 2022 10:52:47 -0500
Subject: ftrace/x86: Add back ftrace_expected for ftrace bug reports
Git-commit: fd3dc56253acbe9c641a66d312d8393cd55eb04c
Patch-mainline: v6.2-rc1
References: git-fixes
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@mail.gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20221209105247.01d4e51d@gandalf.local.home
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>
Acked-by: Petr Pavlu <petr.pavlu@suse.com>
---
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;
}
}