From 0284b03ba3f47da53b6b46293a3d586c08829f7e Mon Sep 17 00:00:00 2001 From: Timothy E Baldwin Date: Thu, 12 May 2016 18:47:30 +0100 Subject: linux-user: Support for restarting system calls for x86 targets Update the x86 main loop and sigreturn code: * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn * set all guest CPU state within signal.c code rather than passing it back out as the "return code" from do_sigreturn() * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication that the main loop should not touch EAX Signed-off-by: Timothy Edward Baldwin Message-id: 1441497448-32489-5-git-send-email-T.E.Baldwin99@members.leeds.ac.uk Reviewed-by: Peter Maydell [PMM: Commit message tweaks; drop TARGET_USE_ERESTARTSYS define] Signed-off-by: Peter Maydell Signed-off-by: Riku Voipio --- linux-user/main.c | 47 +++++++++++++++++++++++++++++------------------ linux-user/signal.c | 15 +++++++-------- linux-user/syscall.c | 2 -- 3 files changed, 36 insertions(+), 28 deletions(-) diff --git a/linux-user/main.c b/linux-user/main.c index 95ed11d..da5a033 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -285,6 +285,7 @@ void cpu_loop(CPUX86State *env) CPUState *cs = CPU(x86_env_get_cpu(env)); int trapnr; abi_ulong pc; + abi_ulong ret; target_siginfo_t info; for(;;) { @@ -294,28 +295,38 @@ void cpu_loop(CPUX86State *env) switch(trapnr) { case 0x80: /* linux syscall from int $0x80 */ - env->regs[R_EAX] = do_syscall(env, - env->regs[R_EAX], - env->regs[R_EBX], - env->regs[R_ECX], - env->regs[R_EDX], - env->regs[R_ESI], - env->regs[R_EDI], - env->regs[R_EBP], - 0, 0); + ret = do_syscall(env, + env->regs[R_EAX], + env->regs[R_EBX], + env->regs[R_ECX], + env->regs[R_EDX], + env->regs[R_ESI], + env->regs[R_EDI], + env->regs[R_EBP], + 0, 0); + if (ret == -TARGET_ERESTARTSYS) { + env->eip -= 2; + } else if (ret != -TARGET_QEMU_ESIGRETURN) { + env->regs[R_EAX] = ret; + } break; #ifndef TARGET_ABI32 case EXCP_SYSCALL: /* linux syscall from syscall instruction */ - env->regs[R_EAX] = do_syscall(env, - env->regs[R_EAX], - env->regs[R_EDI], - env->regs[R_ESI], - env->regs[R_EDX], - env->regs[10], - env->regs[8], - env->regs[9], - 0, 0); + ret = do_syscall(env, + env->regs[R_EAX], + env->regs[R_EDI], + env->regs[R_ESI], + env->regs[R_EDX], + env->regs[10], + env->regs[8], + env->regs[9], + 0, 0); + if (ret == -TARGET_ERESTARTSYS) { + env->eip -= 2; + } else if (ret != -TARGET_QEMU_ESIGRETURN) { + env->regs[R_EAX] = ret; + } break; #endif case EXCP0B_NOSEG: diff --git a/linux-user/signal.c b/linux-user/signal.c index 04c21d0..11ddd05 100644 --- a/linux-user/signal.c +++ b/linux-user/signal.c @@ -1024,7 +1024,7 @@ give_sigsegv: } static int -restore_sigcontext(CPUX86State *env, struct target_sigcontext *sc, int *peax) +restore_sigcontext(CPUX86State *env, struct target_sigcontext *sc) { unsigned int err = 0; abi_ulong fpstate_addr; @@ -1042,6 +1042,7 @@ restore_sigcontext(CPUX86State *env, struct target_sigcontext *sc, int *peax) env->regs[R_EBX] = tswapl(sc->ebx); env->regs[R_EDX] = tswapl(sc->edx); env->regs[R_ECX] = tswapl(sc->ecx); + env->regs[R_EAX] = tswapl(sc->eax); env->eip = tswapl(sc->eip); cpu_x86_load_seg(env, R_CS, lduw_p(&sc->cs) | 3); @@ -1059,7 +1060,6 @@ restore_sigcontext(CPUX86State *env, struct target_sigcontext *sc, int *peax) cpu_x86_frstor(env, fpstate_addr, 1); } - *peax = tswapl(sc->eax); return err; badframe: return 1; @@ -1071,7 +1071,7 @@ long do_sigreturn(CPUX86State *env) abi_ulong frame_addr = env->regs[R_ESP] - 8; target_sigset_t target_set; sigset_t set; - int eax, i; + int i; trace_user_do_sigreturn(env, frame_addr); if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) @@ -1086,10 +1086,10 @@ long do_sigreturn(CPUX86State *env) do_sigprocmask(SIG_SETMASK, &set, NULL); /* restore registers */ - if (restore_sigcontext(env, &frame->sc, &eax)) + if (restore_sigcontext(env, &frame->sc)) goto badframe; unlock_user_struct(frame, frame_addr, 0); - return eax; + return -TARGET_QEMU_ESIGRETURN; badframe: unlock_user_struct(frame, frame_addr, 0); @@ -1102,7 +1102,6 @@ long do_rt_sigreturn(CPUX86State *env) abi_ulong frame_addr; struct rt_sigframe *frame; sigset_t set; - int eax; frame_addr = env->regs[R_ESP] - 4; trace_user_do_rt_sigreturn(env, frame_addr); @@ -1111,7 +1110,7 @@ long do_rt_sigreturn(CPUX86State *env) target_to_host_sigset(&set, &frame->uc.tuc_sigmask); do_sigprocmask(SIG_SETMASK, &set, NULL); - if (restore_sigcontext(env, &frame->uc.tuc_mcontext, &eax)) { + if (restore_sigcontext(env, &frame->uc.tuc_mcontext)) { goto badframe; } @@ -1121,7 +1120,7 @@ long do_rt_sigreturn(CPUX86State *env) } unlock_user_struct(frame, frame_addr, 0); - return eax; + return -TARGET_QEMU_ESIGRETURN; badframe: unlock_user_struct(frame, frame_addr, 0); diff --git a/linux-user/syscall.c b/linux-user/syscall.c index f4c2e19..a4a1af7 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -6940,12 +6940,10 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, break; #ifdef TARGET_NR_sigreturn case TARGET_NR_sigreturn: - /* NOTE: ret is eax, so not transcoding must be done */ ret = do_sigreturn(cpu_env); break; #endif case TARGET_NR_rt_sigreturn: - /* NOTE: ret is eax, so not transcoding must be done */ ret = do_rt_sigreturn(cpu_env); break; case TARGET_NR_sethostname: -- cgit v1.1