linux-kernel - [tip:x86/asm] x86/asm: Mark all top level asm statements as .text

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Message-ID: <tip-c03e27506a564ec7db1b179e7464835901f49751@git.kernel.org>
Date:   Fri, 19 Apr 2019 08:52:06 -0700
From:   tip-bot for Andi Kleen <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mingo@...nel.org, hpa@...or.com, tglx@...utronix.de,
        ak@...ux.intel.com, linux-kernel@...r.kernel.org
Subject: [tip:x86/asm] x86/asm: Mark all top level asm statements as .text

Commit-ID:  c03e27506a564ec7db1b179e7464835901f49751
Gitweb:     https://git.kernel.org/tip/c03e27506a564ec7db1b179e7464835901f49751
Author:     Andi Kleen <ak@...ux.intel.com>
AuthorDate: Fri, 29 Mar 2019 17:47:35 -0700
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 19 Apr 2019 17:46:55 +0200

x86/asm: Mark all top level asm statements as .text

With gcc toplevel assembler statements that do not mark themselves as .text
may end up in other sections. This causes LTO boot crashes because various
assembler statements ended up in the middle of the initcall section. It's
also a latent problem without LTO, although it's currently not known to
cause any real problems.

According to the gcc team it's expected behavior.

Always mark all the top level assembler statements as text so that they
switch to the right section.

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/20190330004743.29541-1-andi@firstfloor.org

---
 arch/x86/kernel/cpu/amd.c      | 3 ++-
 arch/x86/kernel/kprobes/core.c | 1 +
 arch/x86/lib/error-inject.c    | 1 +
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 01004bfb1a1b..1bcb489e07e7 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -83,7 +83,8 @@ static inline int wrmsrl_amd_safe(unsigned msr, unsigned long long val)
  */
 
 extern __visible void vide(void);
-__asm__(".globl vide\n"
+__asm__(".text\n"
+	".globl vide\n"
 	".type vide, @function\n"
 	".align 4\n"
 	"vide: ret\n");
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index a034cb808e7e..31ab91c9c4e9 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -715,6 +715,7 @@ NOKPROBE_SYMBOL(kprobe_int3_handler);
  * calls trampoline_handler() runs, which calls the kretprobe's handler.
  */
 asm(
+	".text\n"
 	".global kretprobe_trampoline\n"
 	".type kretprobe_trampoline, @function\n"
 	"kretprobe_trampoline:\n"
diff --git a/arch/x86/lib/error-inject.c b/arch/x86/lib/error-inject.c
index 3cdf06128d13..be5b5fb1598b 100644
--- a/arch/x86/lib/error-inject.c
+++ b/arch/x86/lib/error-inject.c
@@ -6,6 +6,7 @@
 asmlinkage void just_return_func(void);
 
 asm(
+	".text\n"
 	".type just_return_func, @function\n"
 	".globl just_return_func\n"
 	"just_return_func:\n"