linux-kernel - [PATCH] x86: fix section mismatch on load_ucode

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Message-ID: <1371654926-11729-1-git-send-email-paul.gortmaker@windriver.com>
Date:	Wed, 19 Jun 2013 11:15:26 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	<x86@...nel.org>
CC:	<linux-kernel@...r.kernel.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, stable <stable@...r.kernel.org>
Subject: [PATCH] x86: fix section mismatch on load_ucode_ap

We are in the process of removing all the __cpuinit annotations.
While working on making that change, an existing problem was
made evident:

  WARNING: arch/x86/kernel/built-in.o(.text+0x198f2): Section mismatch
  in reference from the function cpu_init() to the function
  .init.text:load_ucode_ap()   The function cpu_init() references
  the function __init load_ucode_ap().  This is often because cpu_init
  lacks a __init annotation or the annotation of load_ucode_ap is wrong.

This now appears because in my working tree, cpu_init() is no longer
tagged as __cpuinit, and so the audit picks up the mismatch.  The 2nd
hypothesis from the audit is the correct one, as there was an incorrect
__init tag on the prototype in the header (but __cpuinit was used on
the function itself.)

The audit is telling us that the prototype's __init annotation took
effect and the function did land in the .init.text section.  Checking
with objdump on a mainline tree that still has __cpuinit shows that
the __cpuinit on the function takes precedence over the __init on the
prototype, but that won't be true once we make __cpuinit a no-op.

Even though we are removing __cpuinit, we temporarily align both
the function and the prototype on __cpuinit so that the changeset
can be applied to stable trees  if desired.

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: stable <stable@...r.kernel.org> # 3.9+
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 arch/x86/include/asm/microcode.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h
index 6825e2e..6bc3985 100644
--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -60,11 +60,11 @@ static inline void __exit exit_amd_microcode(void) {}
 #ifdef CONFIG_MICROCODE_EARLY
 #define MAX_UCODE_COUNT 128
 extern void __init load_ucode_bsp(void);
-extern __init void load_ucode_ap(void);
+extern void __cpuinit load_ucode_ap(void);
 extern int __init save_microcode_in_initrd(void);
 #else
 static inline void __init load_ucode_bsp(void) {}
-static inline __init void load_ucode_ap(void) {}
+static inline void __cpuinit load_ucode_ap(void) {}
 static inline int __init save_microcode_in_initrd(void)
 {
 	return 0;
-- 
1.8.1.2

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