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Message-ID: <20130620003654.GB15693@windriver.com>
Date: Wed, 19 Jun 2013 20:36:54 -0400
From: Paul Gortmaker <paul.gortmaker@...driver.com>
To: Yinghai Lu <yinghai@...nel.org>
CC: Ingo Molnar <mingo@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
Ingo Molnar <mingo@...hat.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...ux.intel.com>,
"linux-tip-commits@...r.kernel.org"
<linux-tip-commits@...r.kernel.org>
Subject: Re: [tip:x86/urgent] x86: Fix section mismatch on load_ucode_ap
[Re: [tip:x86/urgent] x86: Fix section mismatch on load_ucode_ap] On 19/06/2013 (Wed 17:02) Yinghai Lu wrote:
> On Wed, Jun 19, 2013 at 3:03 PM, tip-bot for Paul Gortmaker
> <tipbot@...or.com> wrote:
> > Commit-ID: 949785996ec2250fa958fc3a924e5186e9a8fa2c
> > Gitweb: http://git.kernel.org/tip/949785996ec2250fa958fc3a924e5186e9a8fa2c
> > Author: Paul Gortmaker <paul.gortmaker@...driver.com>
> > AuthorDate: Wed, 19 Jun 2013 11:15:26 -0400
> > Committer: H. Peter Anvin <hpa@...ux.intel.com>
> > CommitDate: Wed, 19 Jun 2013 14:43:59 -0700
> >
> > 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.
> >
> > [ hpa: build fix only, no object code change ]
> >
> > 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>
> > Link: http://lkml.kernel.org/r/1371654926-11729-1-git-send-email-paul.gortmaker@windriver.com
> > Signed-off-by: H. Peter Anvin <hpa@...ux.intel.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);
>
> why not just dropping __init in header file?
Why? Because then the mis-match remains, and the next person along who
cares about understanding what it really means, has to repeat the same
research that I did in order to understand what was really happening
(or in this case, not happening). Why do that? That doesn't make sense.
Paul.
--
>
>
> > 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;
> > --
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