Re: [PATCH] Fix output of LD_SHOW_AUXV=1.

[Carlos O'Donell <carlos@redhat.com>]

On 3/12/19 11:06 AM, Stefan Liebler wrote:
> commit 988376a08d6d36ea321203b9c039db4b266609ae
> Author: Stefan Liebler <stli@linux.ibm.com>
> Date:   Fri Mar 8 11:18:53 2019 +0100
> 
>     Fix output of LD_SHOW_AUXV=1.
>     
>     Starting with commit 1616d034b61622836d3a36af53dcfca7624c844e
>     the output was corrupted on some platforms as _dl_procinfo
>     was called for every auxv entry and on some architectures like s390
>     all entries were represented as "AT_HWCAP".
>     
>     This patch is removing the condition and let _dl_procinfo decide if
>     an entry is printed in a platform specific or generic way.
>     This patch also adjusts all _dl_procinfo implementations which assumed
>     that they are only called for AT_HWCAP or AT_HWCAP2. They are now just
>     returning a non-zero-value for entries which are not handled platform
>     specifc.
>     
>     ChangeLog:
>     
>             * elf/dl-sysdep.c (_dl_show_auxv): Remove condition and always
>             call _dl_procinfo.
>             * sysdeps/unix/sysv/linux/s390/dl-procinfo.h (_dl_procinfo):
>             Ignore types other than AT_HWCAP.
>             * sysdeps/sparc/dl-procinfo.h (_dl_procinfo): Likewise.
>             * sysdeps/unix/sysv/linux/i386/dl-procinfo.h (_dl_procinfo):
>             Likewise.

Thanks for the cleanup, this makes it really clear how this is intended to work.

OK for master if you...
- Fix ARM and POWERPC backend _dl_procinfo to remove "/* This should not happen.  */"
  comment in dl-procinfo.c. It *does* happen now because we pass all options to
  the machine version first.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

> diff --git a/elf/dl-sysdep.c b/elf/dl-sysdep.c
> index 5f6c679a3f..5d19b100b2 100644
> --- a/elf/dl-sysdep.c
> +++ b/elf/dl-sysdep.c
> @@ -328,14 +328,9 @@ _dl_show_auxv (void)
>        assert (AT_NULL == 0);
>        assert (AT_IGNORE == 1);
>  
> -      if (av->a_type == AT_HWCAP || av->a_type == AT_HWCAP2
> -	  || AT_L1I_CACHEGEOMETRY || AT_L1D_CACHEGEOMETRY
> -	  || AT_L2_CACHEGEOMETRY || AT_L3_CACHEGEOMETRY)
> -	{
> -	  /* These are handled in a special way per platform.  */
> -	  if (_dl_procinfo (av->a_type, av->a_un.a_val) == 0)
> -	    continue;
> -	}
> +      /* Some entries are handled in a special way per platform.  */
> +      if (_dl_procinfo (av->a_type, av->a_un.a_val) == 0)
> +	continue;

OK.

OK. ARM backend returns -1 with default handling.

OK. POWERPC backend return -1 with default handling.

>  
>        if (idx < sizeof (auxvars) / sizeof (auxvars[0])
>  	  && auxvars[idx].form != unknown)
> diff --git a/sysdeps/sparc/dl-procinfo.h b/sysdeps/sparc/dl-procinfo.h
> index 282b8c5117..cc2687e99b 100644
> --- a/sysdeps/sparc/dl-procinfo.h
> +++ b/sysdeps/sparc/dl-procinfo.h
> @@ -32,7 +32,7 @@ _dl_procinfo (unsigned int type, unsigned long int word)
>    int i;
>  
>    /* Fallback to unknown output mechanism.  */
> -  if (type == AT_HWCAP2)
> +  if (type != AT_HWCAP)

OK.

>      return -1;
>  
>    _dl_printf ("AT_HWCAP:   ");
> diff --git a/sysdeps/unix/sysv/linux/i386/dl-procinfo.h b/sysdeps/unix/sysv/linux/i386/dl-procinfo.h
> index 22b43431bc..3aef14c6c1 100644
> --- a/sysdeps/unix/sysv/linux/i386/dl-procinfo.h
> +++ b/sysdeps/unix/sysv/linux/i386/dl-procinfo.h
> @@ -31,7 +31,7 @@ _dl_procinfo (unsigned int type, unsigned long int word)
>    int i;
>  
>    /* Fallback to unknown output mechanism.  */
> -  if (type == AT_HWCAP2)
> +  if (type != AT_HWCAP)

OK.

>      return -1;
>  
>    _dl_printf ("AT_HWCAP:   ");
> diff --git a/sysdeps/unix/sysv/linux/s390/dl-procinfo.h b/sysdeps/unix/sysv/linux/s390/dl-procinfo.h
> index 19329a335b..16739fd6cd 100644
> --- a/sysdeps/unix/sysv/linux/s390/dl-procinfo.h
> +++ b/sysdeps/unix/sysv/linux/s390/dl-procinfo.h
> @@ -33,7 +33,7 @@ _dl_procinfo (unsigned int type, unsigned long int word)
>    int i;
>  
>    /* Fallback to unknown output mechanism.  */
> -  if (type == AT_HWCAP2)
> +  if (type != AT_HWCAP)

OK.

>      return -1;
>  
>    _dl_printf ("AT_HWCAP:   ");


-- 
Cheers,
Carlos.