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

On Sat, Jan 18, 2025 at 10:41:29AM -0800, H. Peter Anvin wrote:
> 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]>

Glad I got it right, even if I did show up late.  ;-)

Regardless, thank you for looking it over!

							Thanx, Paul