Le 15/03/2020 à 16:52, Vincent Fazio a écrit :
> From: Vincent Fazio <vfa...@gmail.com>
>
> In ELFv2, function pointers are entry points and are in host endianness.
"host endianness" is misleading here. "target endianness" is better.
>
> Previously, the signal handler would be swapped if the target CPU was a
> different endianness than the host. This would cause a SIGSEGV when
> attempting to translate the opcode pointed to by the swapped address.
This is correct.
> Thread 1 "qemu-ppc64" received signal SIGSEGV, Segmentation fault.
> 0x00000000600a9257 in ldl_he_p (ptr=0x4c2c061000000000) at
> qemu/include/qemu/bswap.h:351
> 351 __builtin_memcpy(&r, ptr, sizeof(r));
>
> #0 0x00000000600a9257 in ldl_he_p (ptr=0x4c2c061000000000) at
> qemu/include/qemu/bswap.h:351
> #1 0x00000000600a92fe in ldl_be_p (ptr=0x4c2c061000000000) at
> qemu/include/qemu/bswap.h:449
> #2 0x00000000600c0790 in translator_ldl_swap at
> qemu/include/exec/translator.h:201
> #3 0x000000006011c1ab in ppc_tr_translate_insn at
> qemu/target/ppc/translate.c:7856
> #4 0x000000006005ae70 in translator_loop at qemu/accel/tcg/translator.c:102
>
> Now, no swap is performed and execution continues properly.
>
> Signed-off-by: Vincent Fazio <vfa...@gmail.com>
> ---
> linux-user/ppc/signal.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/linux-user/ppc/signal.c b/linux-user/ppc/signal.c
> index 5b82af6cb6..c7f6455170 100644
> --- a/linux-user/ppc/signal.c
> +++ b/linux-user/ppc/signal.c
> @@ -567,9 +567,13 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
> env->nip = tswapl(handler->entry);
> env->gpr[2] = tswapl(handler->toc);
> } else {
> - /* ELFv2 PPC64 function pointers are entry points, but R12
> - * must also be set */
> - env->nip = tswapl((target_ulong) ka->_sa_handler);
> + /*
> + * ELFv2 PPC64 function pointers are entry points and are in host
> + * endianness so should not to be swapped.
"target endianness"
> + *
> + * Note: R12 must also be set.
> + */
> + env->nip = (target_ulong) ka->_sa_handler;
The cast is not needed: nip and _sa_handler are abi_ulong.
> env->gpr[12] = env->nip;
> }
> #else
>
If you repost with the fix I've reported above you can add my:
Reviewed-by: Laurent Vivier <laur...@vivier.eu>
Thanks,
Laurent
