linux-user: Support for restarting system calls for OpenRISC targets

Update the OpenRISC main loop code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state

(We don't implement sigreturn on this target so there is no
code there to update.)

Signed-off-by: Timothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-31-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: tweak commit message; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>

diff --git a/linux-user/main.c b/linux-user/main.c
index 9e6448a..6a0be7d 100644 (file)
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -2724,6 +2724,7 @@ void cpu_loop(CPUOpenRISCState *env)
 {
     CPUState *cs = CPU(openrisc_env_get_cpu(env));
     int trapnr, gdbsig;
+    abi_long ret;
 
     for (;;) {
         cpu_exec_start(cs);
@@ -2769,14 +2770,19 @@ void cpu_loop(CPUOpenRISCState *env)
             break;
         case EXCP_SYSCALL:
             env->pc += 4;   /* 0xc00; */
-            env->gpr[11] = do_syscall(env,
-                                      env->gpr[11], /* return value       */
-                                      env->gpr[3],  /* r3 - r7 are params */
-                                      env->gpr[4],
-                                      env->gpr[5],
-                                      env->gpr[6],
-                                      env->gpr[7],
-                                      env->gpr[8], 0, 0);
+            ret = do_syscall(env,
+                             env->gpr[11], /* return value       */
+                             env->gpr[3],  /* r3 - r7 are params */
+                             env->gpr[4],
+                             env->gpr[5],
+                             env->gpr[6],
+                             env->gpr[7],
+                             env->gpr[8], 0, 0);
+            if (ret == -TARGET_ERESTARTSYS) {
+                env->pc -= 4;
+            } else if (ret != -TARGET_QEMU_ESIGRETURN) {
+                env->gpr[11] = ret;
+            }
             break;
         case EXCP_FPE:
             qemu_log_mask(CPU_LOG_INT, "\nFloating point error\n");

diff --git a/linux-user/openrisc/target_signal.h b/linux-user/openrisc/target_signal.h
index 964aed6..f600501 100644 (file)
--- a/linux-user/openrisc/target_signal.h
+++ b/linux-user/openrisc/target_signal.h
@@ -23,4 +23,5 @@ static inline abi_ulong get_sp_from_cpustate(CPUOpenRISCState *state)
     return state->gpr[1];
 }
 
+
 #endif /* TARGET_SIGNAL_H */