ftrace/x86: Add back ftrace_expected assignment

commit ac6c1b2ca77e722a1e5d651f12f437f2f237e658 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 74c2f88..ceab282 100644 (file)
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -93,6 +93,7 @@ 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;
        }