This is a note to let you know that I've just added the patch titled x86/static_call: Serialize __static_call_fixup() properly 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: x86-static_call-serialize-__static_call_fixup-properly.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 c27c753ea6fd1237f4f96abf8b623d7bab505513 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Date: Tue, 12 Jul 2022 14:01:06 +0200 Subject: x86/static_call: Serialize __static_call_fixup() properly From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> commit c27c753ea6fd1237f4f96abf8b623d7bab505513 upstream. __static_call_fixup() invokes __static_call_transform() without holding text_mutex, which causes lockdep to complain in text_poke_bp(). Adding the proper locking cures that, but as this is either used during early boot or during module finalizing, it's not required to use text_poke_bp(). Add an argument to __static_call_transform() which tells it to use text_poke_early() for it. Fixes: ee88d363d156 ("x86,static_call: Use alternative RET encoding") Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/static_call.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/arch/x86/kernel/static_call.c +++ b/arch/x86/kernel/static_call.c @@ -25,7 +25,8 @@ static const u8 xor5rax[] = { 0x2e, 0x2e static const u8 retinsn[] = { RET_INSN_OPCODE, 0xcc, 0xcc, 0xcc, 0xcc }; -static void __ref __static_call_transform(void *insn, enum insn_type type, void *func) +static void __ref __static_call_transform(void *insn, enum insn_type type, + void *func, bool modinit) { const void *emulate = NULL; int size = CALL_INSN_SIZE; @@ -60,7 +61,7 @@ static void __ref __static_call_transfor if (memcmp(insn, code, size) == 0) return; - if (unlikely(system_state == SYSTEM_BOOTING)) + if (system_state == SYSTEM_BOOTING || modinit) return text_poke_early(insn, code, size); text_poke_bp(insn, code, size, emulate); @@ -108,12 +109,12 @@ void arch_static_call_transform(void *si if (tramp) { __static_call_validate(tramp, true); - __static_call_transform(tramp, __sc_insn(!func, true), func); + __static_call_transform(tramp, __sc_insn(!func, true), func, false); } if (IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE) && site) { __static_call_validate(site, tail); - __static_call_transform(site, __sc_insn(!func, tail), func); + __static_call_transform(site, __sc_insn(!func, tail), func, false); } mutex_unlock(&text_mutex); @@ -139,8 +140,10 @@ bool __static_call_fixup(void *tramp, u8 return false; } + mutex_lock(&text_mutex); if (op == RET_INSN_OPCODE || dest == &__x86_return_thunk) - __static_call_transform(tramp, RET, NULL); + __static_call_transform(tramp, RET, NULL, true); + mutex_unlock(&text_mutex); return true; } Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are queue-5.15/x86-static_call-serialize-__static_call_fixup-properly.patch