This is a note to let you know that I've just added the patch titled
x86/ftrace: Use alternative RET encoding
to the 5.10-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:
x86-ftrace-use-alternative-ret-encoding.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b5f525de67aa9b129b7b93492642c53f85e12d82 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Tue, 14 Jun 2022 23:15:40 +0200
Subject: x86/ftrace: Use alternative RET encoding
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Upstream commit: 1f001e9da6bbf482311e45e48f53c2bd2179e59c
Use the return thunk in ftrace trampolines, if needed.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/ftrace.c | 7 +++++--
1 file changed, 5 insertions(+), 2 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 1 + IS_ENABLED(CONFIG_SLS)
+#define RET_SIZE (IS_ENABLED(CONFIG_RETPOLINE) ? 5 : 1 + IS_ENABLED(CONFIG_SLS))
static unsigned long
create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
@@ -367,7 +367,10 @@ create_trampoline(struct ftrace_ops *ops
goto fail;
ip = trampoline + size;
- memcpy(ip, retq, RET_SIZE);
+ if (cpu_feature_enabled(X86_FEATURE_RETHUNK))
+ __text_gen_insn(ip, JMP32_INSN_OPCODE, ip, &__x86_return_thunk, JMP32_INSN_SIZE);
+ else
+ memcpy(ip, retq, sizeof(retq));
/* 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 peterz@xxxxxxxxxxxxx are
queue-5.10/x86-ftrace-use-alternative-ret-encoding.patch
queue-5.10/x86-uaccess-implement-macros-for-cmpxchg-on-user-add.patch
queue-5.10/x86-text-patching-make-text_gen_insn-play-nice-with-annotate_noendbr.patch
queue-5.10/x86-alternative-make-custom-return-thunk-unconditional.patch
queue-5.10/task_stack-x86-cea-force-inline-stack-helpers.patch
queue-5.10/x86-returnthunk-allow-different-return-thunks.patch
queue-5.10/x86-ibt-paravirt-use-text_gen_insn-for-paravirt_patch.patch
queue-5.10/sched-rt-fix-sysctl_sched_rr_timeslice-intial-value.patch
queue-5.10/sched-rt-sysctl_sched_rr_timeslice-show-default-timeslice-after-reset.patch
