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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 <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-5-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: Commit message tweaks; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
This commit is contained in:
Timothy E Baldwin 2016-05-12 18:47:30 +01:00 committed by Riku Voipio
parent 499b5d176a
commit 0284b03ba3
3 changed files with 36 additions and 28 deletions
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47
linux-user/main.c
View File

@ -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:

15
linux-user/signal.c
View File

@ -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);

2
linux-user/syscall.c
View File

@ -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: