From: Steven Rostedt (Google) <rostedt@goodmis.org>
Date: Tue, 26 Jul 2022 14:18:51 +0000 (-0400)
Subject: ftrace/x86: Add back ftrace_expected assignment
X-Git-Tag: baikal/mips/sdk5.9~99
X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=04955c3581a3a471422ae239933d51bd6e58a8ea;p=kernel.git

ftrace/x86: Add back ftrace_expected assignment

commit bbadcedb9e5c2d62aa5f35202d03810a1dba6a99 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: cdfebad7bc9b ("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 74c2f88a43d0c..ceab282775461 100644
--- 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;
 	}