linux-kernel - Re: [PATCH v4 2/2] mips: Differentiate between 32 and 64 bit ELF header

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Message-ID: <20160211153009.GG11091@linux-mips.org>
Date:	Thu, 11 Feb 2016 16:30:09 +0100
From:	Ralf Baechle <ralf@...ux-mips.org>
To:	"Maciej W. Rozycki" <macro@...tec.com>
Cc:	Daniel Wagner <daniel.wagner@...-carit.de>,
	linux-kernel@...r.kernel.org, linux-mips@...ux-mips.org
Subject: Re: [PATCH v4 2/2] mips: Differentiate between 32 and 64 bit ELF
 header

On Thu, Feb 11, 2016 at 02:58:55PM +0000, Maciej W. Rozycki wrote:
> Date:   Thu, 11 Feb 2016 14:58:55 +0000
> From: "Maciej W. Rozycki" <macro@...tec.com>
> To: Ralf Baechle <ralf@...ux-mips.org>
> CC: Daniel Wagner <daniel.wagner@...-carit.de>,
>  linux-kernel@...r.kernel.org, linux-mips@...ux-mips.org
> Subject: Re: [PATCH v4 2/2] mips: Differentiate between 32 and 64 bit ELF
>  header
> Content-Type: text/plain; charset="ISO-8859-7"
> 
> On Thu, 11 Feb 2016, Maciej W. Rozycki wrote:
> 
> > > > Signed-off-by: Daniel Wagner <daniel.wagner@...-carit.de>
> > > > Suggested-by: Maciej W. Rozycki <macro@...tec.com>
> > > > Reviewed-by: Maciej W. Rozycki <macro@...tec.com>
> > > > Reported-by: Fengguang Wu <fengguang.wu@...el.com>
> > > 
> > > Thanks, applied.
> > > 
> > > I'm getting a less spectacular warning from gcc 5.2:
> > > 
> > >   CC      fs/proc/vmcore.o
> > > fs/proc/vmcore.c: In function ‘parse_crash_elf64_headers’:
> > > fs/proc/vmcore.c:939:47: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
> > 
> >  Yes, the temporaries still need to have their pointed types changed, to 
> > `Elf32_Ehdr' and `Elf64_Ehdr' respectively, as in the original change.
> > 
> >  I had it mentioned in a WIP version of my review (stating that it would 
> > verify that the correct type is used by the caller), but then deleted that 
> > part inadvertently, sigh.
> 
>  Hold on, I was right in dropping it actually.
> 
>  With your v4 change in place all `parse_crash_elf64_headers' is supposed 
> to call is `mips_elf_check_machine' and that doesn't make any 
> intialisations, it just dereferences the pointer passed once.  This error 
> does not make any sense to me and line 939 isn't even in 
> `parse_crash_elf64_headers', which starts at line 999, it's in 
> `process_ptload_program_headers_elf32'.
> 
>  So Ralf, what tree are you using that is off from LMO/Linus by 60 lines?

That was 3.16, the oldest version affected.  But I'm getting the same
messages with different line numbers on more recent kernels including
the master branch.

  Ralf