This is a note to let you know that I've just added the patch titled
Revert "x86/ftrace: Use alternative RET encoding"
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
revert-x86-ftrace-use-alternative-ret-encoding.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6669394b61f141a351399013cfde5bd0a0fcb3fb Mon Sep 17 00:00:00 2001
From: "Borislav Petkov (AMD)" <bp@xxxxxxxxx>
Date: Thu, 22 Feb 2024 13:46:09 +0100
Subject: Revert "x86/ftrace: Use alternative RET encoding"
From: "Borislav Petkov (AMD)" <bp@xxxxxxxxx>
This reverts commit 3eb602ad6a94a76941f93173131a71ad36fa1324.
Revert the backport of upstream commit
1f001e9da6bb ("x86/ftrace: Use alternative RET encoding")
in favor of a proper backport after backporting the commit which adds
__text_gen_insn().
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/ftrace.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -311,7 +311,7 @@ union ftrace_op_code_union {
} __attribute__((packed));
};
-#define RET_SIZE (IS_ENABLED(CONFIG_RETPOLINE) ? 5 : 1 + IS_ENABLED(CONFIG_SLS))
+#define RET_SIZE 1 + IS_ENABLED(CONFIG_SLS)
static unsigned long
create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
@@ -367,12 +367,7 @@ create_trampoline(struct ftrace_ops *ops
goto fail;
ip = trampoline + size;
-
- /* The trampoline ends with ret(q) */
- if (cpu_feature_enabled(X86_FEATURE_RETHUNK))
- memcpy(ip, text_gen_insn(JMP32_INSN_OPCODE, ip, &__x86_return_thunk), JMP32_INSN_SIZE);
- else
- memcpy(ip, retq, sizeof(retq));
+ memcpy(ip, retq, RET_SIZE);
/* No need to test direct calls on created trampolines */
if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
Patches currently in stable-queue which might be from bp@xxxxxxxxx are
queue-5.15/revert-x86-alternative-make-custom-return-thunk-unconditional.patch
queue-5.15/revert-x86-ftrace-use-alternative-ret-encoding.patch
queue-5.15/x86-ftrace-use-alternative-ret-encoding.patch
queue-5.15/x86-text-patching-make-text_gen_insn-play-nice-with-annotate_noendbr.patch
queue-5.15/x86-alternative-make-custom-return-thunk-unconditional.patch
queue-5.15/x86-returnthunk-allow-different-return-thunks.patch
queue-5.15/x86-ibt-paravirt-use-text_gen_insn-for-paravirt_patch.patch
