From 75da499733696889453b3fda9ae0f0f5c28fcd6b Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Tue, 23 Mar 2021 12:43:39 -0600 Subject: [PATCH] linux-user/ppc: Fix msr updates for signal handling In save_user_regs, there are two bugs where we OR in a bit number instead of the bit, clobbering the low bits of MSR. However: The MSR_VR and MSR_SPE bits control the availability of the insns. If the bits were not already set in MSR, then any attempt to access those registers would result in SIGILL. For linux-user, we always initialize MSR to the capabilities of the cpu. We *could* add checks vs MSR where we currently check insn_flags and insn_flags2, but we know they match. Also, there's a stray cut-and-paste comment in restore. Then, do not force little-endian binaries into big-endian mode. Finally, use ppc_store_msr for the update to affect hflags. Which is the reason none of these bugs were previously noticed. Signed-off-by: Richard Henderson Message-Id: <20210323184340.619757-10-richard.henderson@linaro.org> Signed-off-by: David Gibson --- linux-user/ppc/cpu_loop.c | 5 +++-- linux-user/ppc/signal.c | 23 +++++++++++------------ 2 files changed, 14 insertions(+), 14 deletions(-) diff --git a/linux-user/ppc/cpu_loop.c b/linux-user/ppc/cpu_loop.c index df71e15a25..4a0f6c8dc2 100644 --- a/linux-user/ppc/cpu_loop.c +++ b/linux-user/ppc/cpu_loop.c @@ -492,11 +492,12 @@ void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs) #if defined(TARGET_PPC64) int flag = (env->insns_flags2 & PPC2_BOOKE206) ? MSR_CM : MSR_SF; #if defined(TARGET_ABI32) - env->msr &= ~((target_ulong)1 << flag); + ppc_store_msr(env, env->msr & ~((target_ulong)1 << flag)); #else - env->msr |= (target_ulong)1 << flag; + ppc_store_msr(env, env->msr | (target_ulong)1 << flag); #endif #endif + env->nip = regs->nip; for(i = 0; i < 32; i++) { env->gpr[i] = regs->gpr[i]; diff --git a/linux-user/ppc/signal.c b/linux-user/ppc/signal.c index b78613f7c8..bad38f8ed9 100644 --- a/linux-user/ppc/signal.c +++ b/linux-user/ppc/signal.c @@ -261,9 +261,6 @@ static void save_user_regs(CPUPPCState *env, struct target_mcontext *frame) __put_user(avr->u64[PPC_VEC_HI], &vreg->u64[0]); __put_user(avr->u64[PPC_VEC_LO], &vreg->u64[1]); } - /* Set MSR_VR in the saved MSR value to indicate that - frame->mc_vregs contains valid data. */ - msr |= MSR_VR; #if defined(TARGET_PPC64) vrsave = (uint32_t *)&frame->mc_vregs.altivec[33]; /* 64-bit needs to put a pointer to the vectors in the frame */ @@ -300,9 +297,6 @@ static void save_user_regs(CPUPPCState *env, struct target_mcontext *frame) for (i = 0; i < ARRAY_SIZE(env->gprh); i++) { __put_user(env->gprh[i], &frame->mc_vregs.spe[i]); } - /* Set MSR_SPE in the saved MSR value to indicate that - frame->mc_vregs contains valid data. */ - msr |= MSR_SPE; __put_user(env->spe_fscr, &frame->mc_vregs.spe[32]); } #endif @@ -354,8 +348,10 @@ static void restore_user_regs(CPUPPCState *env, __get_user(msr, &frame->mc_gregs[TARGET_PT_MSR]); /* If doing signal return, restore the previous little-endian mode. */ - if (sig) - env->msr = (env->msr & ~(1ull << MSR_LE)) | (msr & (1ull << MSR_LE)); + if (sig) { + ppc_store_msr(env, ((env->msr & ~(1ull << MSR_LE)) | + (msr & (1ull << MSR_LE)))); + } /* Restore Altivec registers if necessary. */ if (env->insns_flags & PPC_ALTIVEC) { @@ -376,8 +372,6 @@ static void restore_user_regs(CPUPPCState *env, __get_user(avr->u64[PPC_VEC_HI], &vreg->u64[0]); __get_user(avr->u64[PPC_VEC_LO], &vreg->u64[1]); } - /* Set MSR_VEC in the saved MSR value to indicate that - frame->mc_vregs contains valid data. */ #if defined(TARGET_PPC64) vrsave = (uint32_t *)&v_regs[33]; #else @@ -468,7 +462,7 @@ void setup_frame(int sig, struct target_sigaction *ka, env->nip = (target_ulong) ka->_sa_handler; /* Signal handlers are entered in big-endian mode. */ - env->msr &= ~(1ull << MSR_LE); + ppc_store_msr(env, env->msr & ~(1ull << MSR_LE)); unlock_user_struct(frame, frame_addr, 1); return; @@ -563,8 +557,13 @@ void setup_rt_frame(int sig, struct target_sigaction *ka, env->nip = (target_ulong) ka->_sa_handler; #endif +#ifdef TARGET_WORDS_BIGENDIAN /* Signal handlers are entered in big-endian mode. */ - env->msr &= ~(1ull << MSR_LE); + ppc_store_msr(env, env->msr & ~(1ull << MSR_LE)); +#else + /* Signal handlers are entered in little-endian mode. */ + ppc_store_msr(env, env->msr | (1ull << MSR_LE)); +#endif unlock_user_struct(rt_sf, rt_sf_addr, 1); return;