linux-kernel - [PATCH 2/3] x86/ptrace: Always inline v8086

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Message-Id: <20220204083015.17317-3-bp@alien8.de>
Date:   Fri,  4 Feb 2022 09:30:14 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Tony Luck <tony.luck@...el.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Marco Elver <elver@...gle.com>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/3] x86/ptrace: Always inline v8086_mode() for instrumentation

From: Borislav Petkov <bp@...e.de>

Instrumentation glue like KASAN causes the following warning:

  vmlinux.o: warning: objtool: mce_gather_info()+0x5f: call to v8086_mode.constprop.0() leaves .noinstr.text section

due to gcc creating a function call for that oneliner. Force-inline it
and even save some vmlinux bytes (.config is close to an allmodconfig):

     text    data     bss     dec     hex filename
  209431677       208257651       34411048        452100376       1af28118	vmlinux.before
  209431519       208257615       34411048        452100182       1af28056	vmlinux.after

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/include/asm/ptrace.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 703663175a5a..4357e0f2cd5f 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -137,7 +137,7 @@ static __always_inline int user_mode(struct pt_regs *regs)
 #endif
 }
 
-static inline int v8086_mode(struct pt_regs *regs)
+static __always_inline int v8086_mode(struct pt_regs *regs)
 {
 #ifdef CONFIG_X86_32
 	return (regs->flags & X86_VM_MASK);
-- 
2.29.2