ftrace/x86: Add back ftrace_expected for ftrace bug reports

Commit Message

Steven Rostedt Dec. 9, 2022, 3:52 p.m. UTC

From: "Steven Rostedt (Google)" <[e-mail]>

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/[e-mail]/

Cc: [e-mail]
Fixes: 768ae4406a5c ("x86/ftrace: Use text_poke()")
Signed-off-by: Steven Rostedt (Google) <[e-mail]>
---
 arch/x86/kernel/ftrace.c | 2 ++
 1 file changed, 2 insertions(+)

Patch

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;
 		}
 	}