linux-kernel - [PATCH] x86/mce: Always inline old MCA stubs

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Date:   Wed, 22 Feb 2023 20:10:54 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86/mce: Always inline old MCA stubs

From: "Borislav Petkov (AMD)" <bp@...en8.de>

The stubs for the ancient MCA support (CONFIG_X86_ANCIENT_MCE) are
normally optimized away on 64-bit builds. However, an allmodconfig one
causes the compiler to add sanitizer calls gunk into them and they exist
as constprop calls. Which objtool then complains about:

  vmlinux.o: warning: objtool: do_machine_check+0xad8: call to \
    pentium_machine_check.constprop.0() leaves .noinstr.text section

due to them missing noinstr. One could tag them "noinstr" but what
should really happen is, they should be forcefully inlined so that all
that gunk gets optimized away and the warning doesn't even have a chance
to fire.

Do so.

No functional changes.

Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
---
 arch/x86/kernel/cpu/mce/internal.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/internal.h b/arch/x86/kernel/cpu/mce/internal.h
index 91a415553c27..d2412ce2d312 100644
--- a/arch/x86/kernel/cpu/mce/internal.h
+++ b/arch/x86/kernel/cpu/mce/internal.h
@@ -244,11 +244,11 @@ noinstr void pentium_machine_check(struct pt_regs *regs);
 noinstr void winchip_machine_check(struct pt_regs *regs);
 static inline void enable_p5_mce(void) { mce_p5_enabled = 1; }
 #else
-static inline void intel_p5_mcheck_init(struct cpuinfo_x86 *c) {}
-static inline void winchip_mcheck_init(struct cpuinfo_x86 *c) {}
-static inline void enable_p5_mce(void) {}
-static inline void pentium_machine_check(struct pt_regs *regs) {}
-static inline void winchip_machine_check(struct pt_regs *regs) {}
+static __always_inline void intel_p5_mcheck_init(struct cpuinfo_x86 *c) {}
+static __always_inline void winchip_mcheck_init(struct cpuinfo_x86 *c) {}
+static __always_inline void enable_p5_mce(void) {}
+static __always_inline void pentium_machine_check(struct pt_regs *regs) {}
+static __always_inline void winchip_machine_check(struct pt_regs *regs) {}
 #endif
 
 noinstr u64 mce_rdmsrl(u32 msr);
-- 
2.35.1