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Re: [PATCH] PowerPC64 ELFv2 ABI 5/6: LD_AUDIT interface changes
- From: Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>
- To: libc-alpha at sourceware dot org
- Cc: Ulrich Weigand <Ulrich dot Weigand at de dot ibm dot com>
- Date: Thu, 21 Nov 2013 11:18:59 -0200
- Subject: Re: [PATCH] PowerPC64 ELFv2 ABI 5/6: LD_AUDIT interface changes
- Authentication-results: sourceware.org; auth=none
- References: <201311122123 dot rACLN7QR019575 at d06av02 dot portsmouth dot uk dot ibm dot com>
Hi Uli,
On 12-11-2013 19:23, Ulrich Weigand wrote:
> Hello,
>
> the ELFv2 ABI changes the calling convention by passing and returning
> structures in registers in more cases than the old ABI:
> http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01145.html
> http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01147.html
>
> For the most part, this does not affect glibc, since glibc assembler
> files do not use structure parameters / return values. However, one
> place is affected: the LD_AUDIT interface provides a structure to
> the audit routine that contains all registers holding function
> argument and return values for the intercepted PLT call.
>
> Since the new ABI now sometimes uses registers to return values
> that were never used for this purpose in the old ABI, this structure
> has to be extended. To force audit routines to be modified for the
> new ABI if necessary, the patch defines v2 variants of the la_ppc64
> types and routines.
This patch is ok, thanks!
>
> In addition, the patch contains two unrelated changes to the
> PLT trampoline routines: it fixes a bug where FPR return values
> were stored in the wrong place, and it removes the unnecessary
> save/restore of CR.
Is this bug user visible? Do we have a bug report for this?