Re: [PATCH RFC x86/asm] Make serialize __always_inline

On January 18, 2025 10:13:38 AM PST, "Paul E. McKenney" <[email protected]> wrote:
>Recent mainline has been getting objtool complaints:
>
>vmlinux.o: warning: objtool: __static_call_update_early+0x33: call to serialize() leaves .noinstr.text section
>
>Bisection converged to a nonsensical commit, and reverting that commit
>did not get rid of the complaints.
>
>So fix this by inspection, marking serialize() __always_inline to match
>the call from sync_core().
>
>This silences the objtool complaint, but of course might not be the
>proper patch.
>
>Signed-off-by: Paul E. McKenney <[email protected]>
>Cc: Thomas Gleixner <[email protected]>
>Cc: Ingo Molnar <[email protected]>
>Cc: Borislav Petkov <[email protected]>
>Cc: Dave Hansen <[email protected]>
>Cc: "H. Peter Anvin" <[email protected]>
>Cc: Josh Poimboeuf <[email protected]>
>Cc: Peter Zijlstra <[email protected]>
>Cc: Nathan Chancellor <[email protected]>
>Cc: <[email protected]>
>Cc: <[email protected]>
>
>diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
>index aec6e2d3aa1d5..98bfc097389c4 100644
>--- a/arch/x86/include/asm/special_insns.h
>+++ b/arch/x86/include/asm/special_insns.h
>@@ -217,7 +217,7 @@ static inline int write_user_shstk_64(u64 __user *addr, u64 val)
> 
> #define nop() asm volatile ("nop")
> 
>-static inline void serialize(void)
>+static __always_inline void serialize(void)
> {
> 	/* Instruction opcode for SERIALIZE; supported in binutils >= 2.35. */
> 	asm volatile(".byte 0xf, 0x1, 0xe8" ::: "memory");

It absolutely is the right thing!

Reviewed-by: H. Peter Anvin (Intel) <[email protected]>