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Re: gdb chokes on core from 64-bit kernel (patch)

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: gdb chokes on core from 64-bit kernel (patch)
From: Andrew Sharp <andy.sharp@onstor.com>
Date: Thu, 15 Nov 2007 11:40:14 -0800
Cc: "linux-mips@linux-mips.org" <linux-mips@linux-mips.org>
In-reply-to: <20071109090757.GA12469@linux-mips.org>
Organization: Onstor
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20071108140322.7bf03aa9@ripper.onstor.net> <20071109090757.GA12469@linux-mips.org>
Sender: linux-mips-bounce@linux-mips.org
On Fri, 9 Nov 2007 09:07:57 +0000 Ralf Baechle <ralf@linux-mips.org>
wrote:

> On Thu, Nov 08, 2007 at 02:03:22PM -0800, Andrew Sharp wrote:
> 
> > The gdb from debian etch (6.4.90-debian) doesn't like core files
> > produced by 64-bit kernel it seems.  I've got this patch which seems
> > to do the job, but I'm unclear on what other implications it might
> > have, if any.
> 
> > diff --git a/arch/mips/kernel/binfmt_elfo32.c
> > b/arch/mips/kernel/binfmt_elfo32.c index 993f7ec..58533dc 100644
> > --- a/arch/mips/kernel/binfmt_elfo32.c
> > +++ b/arch/mips/kernel/binfmt_elfo32.c
> > @@ -54,9 +54,13 @@ typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
> >  
> >  #include <asm/processor.h>
> >  #include <linux/module.h>
> > -#include <linux/elfcore.h>
> >  #include <linux/compat.h>
> >  
> > +void elf32_core_copy_regs(elf_gregset_t grp, struct pt_regs *regs);
> > +#undef ELF_CORE_COPY_REGS
> > +#define ELF_CORE_COPY_REGS(_dest,_regs)
> > elf32_core_copy_regs(_dest,_regs); +#include <linux/elfcore.h>
> > +
> >  #define elf_prstatus elf_prstatus32
> >  struct elf_prstatus32
> >  {
> > @@ -109,9 +113,6 @@ jiffies_to_compat_timeval(unsigned long
> > jiffies, struct comp value->tv_usec = rem / NSEC_PER_USEC;
> >  }
> >  
> > -#undef ELF_CORE_COPY_REGS
> > -#define ELF_CORE_COPY_REGS(_dest,_regs)
> > elf32_core_copy_regs(_dest,_regs); -
> >  void elf32_core_copy_regs(elf_gregset_t grp, struct pt_regs *regs)
> >  {
> >         int i;
> 
> Looks like it's a larger change than needed.

Which change?  Both files?

> > diff --git a/include/asm-mips/reg.h b/include/asm-mips/reg.h
> > index 634b55d..b44b308 100644
> > --- a/include/asm-mips/reg.h
> > +++ b/include/asm-mips/reg.h
> > @@ -12,7 +12,7 @@
> >  #ifndef __ASM_MIPS_REG_H
> >  #define __ASM_MIPS_REG_H
> >  
> > -
> > +#define WANT_COMPAT_REG_H
> >  #if defined(CONFIG_32BIT) || defined(WANT_COMPAT_REG_H)
> >  
> >  #define EF_R0                  6
> > @@ -69,7 +69,7 @@
> >  
> >  #endif
> >  
> > -#ifdef CONFIG_64BIT
> > +#if defined(CONFIG_64BIT) && !defined(WANT_COMPAT_REG_H)
> >  
> >  #define EF_R0                   0
> >  #define EF_R1                   1
> 
> This change breaks the native 64-bit and N32 ptrace and core dumpers.
> 
> I suggest something more minimal like the below patch.  Does that one
> do the trick for you?
> 
>   Ralf
> 
> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
> 
>  arch/mips/kernel/ptrace32.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/mips/kernel/ptrace32.c b/arch/mips/kernel/ptrace32.c
> index 76818be..44109fb 100644
> --- a/arch/mips/kernel/ptrace32.c
> +++ b/arch/mips/kernel/ptrace32.c
> @@ -14,6 +14,9 @@
>   * At this time Linux/MIPS64 only supports syscall tracing, even for
> 32-bit
>   * binaries.
>   */
> +
> +#define WANT_COMPAT_REG_H
> +
>  #include <linux/compiler.h>
>  #include <linux/kernel.h>
>  #include <linux/sched.h>

Without the change to reg.h, this change causes a bunch of
  warning: "EF_R0" redefined
type messages when compiling ptrace32.c.  I tried a combination of mine
and yours, well, really mine except I moved the define for
WANT_COMPAT_REG_H to ptrace32.c, and that did not produce an comprehensible
core file.

Any suggestions?

Cheers,

a


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