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: <20181207025021.GJ17340@MiWiFi-R3L-srv>
Date:   Fri, 7 Dec 2018 10:50:21 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Masayoshi Mizuma <msys.mizuma@...il.com>,
        Chao Fan <fanc.fnst@...fujitsu.com>, bp@...en8.de,
        mingo@...hat.com
Cc:     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 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
Baoquan