| Message ID | 20200319133244.8818-1-vfazio@xes-inc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3,1/1] target/ppc: don't byte swap ELFv2 signal handler | expand |
On Thu, Mar 19, 2020 at 08:32:44AM -0500, Vincent Fazio wrote: > From: Vincent Fazio <vfazio@gmail.com> > > Previously, the signal handler would be byte swapped if the target and > host CPU used different endianness. This would cause a SIGSEGV when > attempting to translate the opcode pointed to by the swapped address. > > 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 > > The signal handler will be byte swapped as a result of the __get_user() > call in sigaction() if it is necessary, no additional swap is required. > > Signed-off-by: Vincent Fazio <vfazio@gmail.com> > Reviewed-by: Laurent Vivier <laurent@vivier.eu> > Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Applied to ppc-for-5.0, thanks. > --- > Changes since v2: > - Explain why the swap is not necessary > > Changes since v1: > - Drop host/target endianness callouts > - Drop unnecessary pointer cast > - Clarify commit message > > linux-user/ppc/signal.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/linux-user/ppc/signal.c b/linux-user/ppc/signal.c > index 5b82af6cb6..b8613c5e1b 100644 > --- a/linux-user/ppc/signal.c > +++ b/linux-user/ppc/signal.c > @@ -567,10 +567,8 @@ 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); > - env->gpr[12] = env->nip; > + /* ELFv2 PPC64 function pointers are entry points. R12 must also be set. */ > + env->gpr[12] = env->nip = ka->_sa_handler; > } > #else > env->nip = (target_ulong) ka->_sa_handler;
diff --git a/linux-user/ppc/signal.c b/linux-user/ppc/signal.c index 5b82af6cb6..b8613c5e1b 100644 --- a/linux-user/ppc/signal.c +++ b/linux-user/ppc/signal.c @@ -567,10 +567,8 @@ 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); - env->gpr[12] = env->nip; + /* ELFv2 PPC64 function pointers are entry points. R12 must also be set. */ + env->gpr[12] = env->nip = ka->_sa_handler; } #else env->nip = (target_ulong) ka->_sa_handler;