linux-kernel - Re: [PATCH v12 1/5] x86/boot: Add get_acpi_rsdp() to parse RSDP in cmdline from KEXEC

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Message-ID: <20181207032001.GA27206@localhost.localdomain>
Date:   Fri, 7 Dec 2018 11:20:01 +0800
From:   Chao Fan <fanc.fnst@...fujitsu.com>
To:     Baoquan He <bhe@...hat.com>
CC:     Masayoshi Mizuma <msys.mizuma@...il.com>, <bp@...en8.de>,
        <mingo@...hat.com>, <linux-kernel@...r.kernel.org>,
        <x86@...nel.org>, <tglx@...utronix.de>, <hpa@...or.com>,
        <keescook@...omium.org>, <indou.takao@...fujitsu.com>,
        <caoj.fnst@...fujitsu.com>
Subject: Re: [PATCH v12 1/5] x86/boot: Add get_acpi_rsdp() to parse RSDP in
 cmdline from KEXEC

On Fri, Dec 07, 2018 at 10:50:21AM +0800, Baoquan He wrote:
>On 12/07/18 at 10:10am, Baoquan He wrote:
>> Hi,
>> 
>> On 11/29/18 at 04:10pm, Masayoshi Mizuma wrote:
>> > > diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
>> > > index 8dd1d5ccae58..e51713fe3add 100644
>> > > --- a/arch/x86/boot/compressed/misc.c
>> > > +++ b/arch/x86/boot/compressed/misc.c
>> > > @@ -12,6 +12,7 @@
>> > >   * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
>> > >   */
>> > >  
>> > > +#define BOOT_CTYPE_H
>> > >  #include "misc.h"
>> > >  #include "error.h"
>> > >  #include "pgtable.h"
>> > > @@ -426,3 +427,7 @@ void fortify_panic(const char *name)
>> > >  {
>> > >  	error("detected buffer overflow");
>> > >  }
>> > > +
>> > > +#ifdef BOOT_STRING
>> > > +#include "../../../../lib/kstrtox.c"
>> > > +#endif
>> > > diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
>> > > index a1d5918765f3..809c31effa4b 100644
>> > > --- a/arch/x86/boot/compressed/misc.h
>> > > +++ b/arch/x86/boot/compressed/misc.h
>> > > @@ -116,3 +116,7 @@ static inline void console_init(void)
>> > >  void set_sev_encryption_mask(void);
>> > >  
>> > >  #endif
>> > > +
>> > > +/* acpitb.c */
>> > > +#define BOOT_STRING
>> > > +extern int kstrtoull(const char *s, unsigned int base, unsigned long long *res);
>> > > diff --git a/lib/kstrtox.c b/lib/kstrtox.c
>> > > index 1006bf70bf74..a0ac1b2257b8 100644
>> > > --- a/lib/kstrtox.c
>> > > +++ b/lib/kstrtox.c
>> > > @@ -126,6 +126,9 @@ int kstrtoull(const char *s, unsigned int base, unsigned long long *res)
>> > >  }
>> > >  EXPORT_SYMBOL(kstrtoull);
>> > >  
>> > > +/* Make compressed period code be able to use kstrtoull(). */
>> > > +#ifndef BOOT_STRING
>> > 
>> > I got the following build error.
>> > 
>> > ]$ make arch/x86/boot/compressed/misc.o
>> >   CALL    scripts/checksyscalls.sh
>> >   DESCEND  objtool
>> >   CC      arch/x86/boot/compressed/misc.o
>> > ld: -r and -pie may not be used together
>> > make[1]: *** [scripts/Makefile.build:294: arch/x86/boot/compressed/misc.o] Error 1
>> > make: *** [Makefile:1715: arch/x86/boot/compressed/misc.o] Error 2
>> 
>> I have met this issue when change code in boot/compressed/kaslr.c.
>> 
>> I remember Ingo merged my patch and found this build error. Since if 
>> CONFIG_MODULES=n EXPORT_SYMBOL is defined as empty in
>> include/linux/export.h, that's why you can only meet it only if
>> CONFIG_MODULES=y.
>> 
>> I remember I just muted it with below code, please check commit
>> d52e7d5a95.
>> 
>> +#define _LINUX_EXPORT_H
>> +#define EXPORT_SYMBOL(sym)
>
>I made below change, it passed. My another question is why you need
>include "lib/kstrtox.c" into misc.c. Does it make sense if you plan to
>use it to replace simple_strtoull() in arch/x86/boot/string.c ?
>
>diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
>index e51713fe3add..777e807756e8 100644
>--- a/arch/x86/boot/compressed/misc.c
>+++ b/arch/x86/boot/compressed/misc.c
>@@ -13,6 +13,8 @@
>  */
> 
> #define BOOT_CTYPE_H
>+#define __DISABLE_EXPORTS
>+
> #include "misc.h"
> #include "error.h"
> #include "pgtable.h"
>
>I just tried to include it into boot/string.c, there's no any problem.

Thanks for your help, I think it's better to include it into
boot/string.c.

Thanks,
Chao Fan
>
>Thanks
>Baoquan
>
>