linux-kernel - [PATCH 13/46] x86/preempt, lto: Mark preempt_schedule_*thunk() as _

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Date:   Mon, 14 Nov 2022 12:43:11 +0100
From:   "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Andi Kleen <andi@...stfloor.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Martin Liska <mliska@...e.cz>, Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 13/46] x86/preempt, lto: Mark preempt_schedule_*thunk() as __visible

From: Andi Kleen <andi@...stfloor.org>

Symbols referenced from assembler (either directly or e.f. from
DEFINE_STATIC_KEY()) need to be global and visible in gcc LTO because
they could end up in a different object file than the assembler. This
can lead to linker errors without this patch.

So mark preempt_schedule_thunk() and preempt_schedule_notrace_thunk() as
__visible.

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Signed-off-by: Andi Kleen <andi@...stfloor.org>
Signed-off-by: Martin Liska <mliska@...e.cz>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 arch/x86/include/asm/preempt.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
index 5f6daea1ee24..c76ec881b23c 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -106,13 +106,13 @@ static __always_inline bool should_resched(int preempt_offset)
 #ifdef CONFIG_PREEMPTION
 
 extern asmlinkage void preempt_schedule(void);
-extern asmlinkage void preempt_schedule_thunk(void);
+extern __visible asmlinkage void preempt_schedule_thunk(void);
 
 #define preempt_schedule_dynamic_enabled	preempt_schedule_thunk
 #define preempt_schedule_dynamic_disabled	NULL
 
 extern asmlinkage void preempt_schedule_notrace(void);
-extern asmlinkage void preempt_schedule_notrace_thunk(void);
+extern __visible asmlinkage void preempt_schedule_notrace_thunk(void);
 
 #define preempt_schedule_notrace_dynamic_enabled	preempt_schedule_notrace_thunk
 #define preempt_schedule_notrace_dynamic_disabled	NULL
-- 
2.38.1