From feb39b62288cb780561ca83b84ca82dceb3cedb9 Mon Sep 17 00:00:00 2001 From: Vincent Fazio Date: Thu, 19 Mar 2020 08:32:44 -0500 Subject: [PATCH] target/ppc: don't byte swap ELFv2 signal handler 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 Reviewed-by: Laurent Vivier Reviewed-by: Richard Henderson Message-Id: <20200319133244.8818-1-vfazio@xes-inc.com> Signed-off-by: David Gibson --- 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 0c4e7ba54caf..ecd99736b7e0 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;