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Date: Thu, 08 May 2014 10:45:24 +0200
From: Alexander Graf <agraf@suse.de>
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Subject: Re: [Qemu-devel] [PATCH 1/3] linux-user: Handle ELFv2 PPC64
	binaries in user mode.
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To: =?UTF-8?B?IkRvdWcgS3dhbiAo6Zec5oyv5b63KSI=?= <dougkwan@google.com>
Cc: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>, riku.voipio@iki.fi, "qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>, QEMU Developers <qemu-devel@nongnu.org>

On 05/08/2014 10:43 AM, Doug Kwan (=E9=97=9C=E6=8C=AF=E5=BE=B7) wrote:
> Hi
>
>
> On Thu, May 8, 2014 at 1:36 AM, Alexander Graf <agraf@suse.de=20
> <mailto:agraf@suse.de>> wrote:      3
>
>
>     Please write bitmasks in hex.
>
> Will fix.
>
>         +
>           /* PowerPC relocations defined by the ABIs */
>           #define R_PPC_NONE            0
>           #define R_PPC_ADDR32          1       /* 32bit absolute
>         address */
>         diff --git a/linux-user/elfload.c b/linux-user/elfload.c
>         index 995f999..b96d64a 100644
>         --- a/linux-user/elfload.c
>         +++ b/linux-user/elfload.c
>         @@ -777,12 +777,18 @@ static uint32_t get_elf_hwcap(void)
>                   NEW_AUX_ENT(AT_IGNOREPPC, AT_IGNOREPPC);    \
>               } while (0)
>           +static inline uint32_t get_ppc64_abi(struct image_info *info=
p);
>         +
>           static inline void init_thread(struct target_pt_regs *_regs,
>         struct image_info *infop)
>           {
>               _regs->gpr[1] =3D infop->start_stack;
>           #if defined(TARGET_PPC64) && !defined(TARGET_ABI32)
>         -    _regs->gpr[2] =3D ldq_raw(infop->entry + 8) + infop->load_=
bias;
>         -    infop->entry =3D ldq_raw(infop->entry) + infop->load_bias;
>         +    if (get_ppc64_abi(infop) < 2) {
>         +      _regs->gpr[2] =3D ldq_raw(infop->entry + 8) +
>         infop->load_bias;
>         +      infop->entry =3D ldq_raw(infop->entry) + infop->load_bia=
s;
>         +    } else {
>         +      _regs->gpr[12] =3D infop->entry;  /* r12 set to global
>         entry address */
>
>
>     Uli, is this correct? Also, why don't w need to adjust for the
>     load_bias with ELFv2 anymore?
>
> No.  This is a bug.  It was not caught by testing because load_bias is=20
> 0 I guess.
>
>
>         +    }
>           #endif
>               _regs->nip =3D infop->entry;
>           }
>         @@ -1152,6 +1158,13 @@ static inline void init_thread(struct
>         target_pt_regs *regs, struct image_info *i
>             #include "elf.h"
>           +#ifdef TARGET_PPC
>         +static inline uint32_t get_ppc64_abi(struct image_info *infop)
>         +{
>         +  return infop->elf_flags & EF_PPC64_ABI;
>         +}
>         +#endif
>
>
>     I'm not sure this is more readable than doing it inline ... :).
>
>
> This is done so because the elf header is not yet included before the=20
> callee.  To eliminate this I need to move the include before ppc's=20
> init_thread.  Is that okay?

Ah, I see. I don't have strong feelings either way. Riku, what would you=20
prefer?


Alex