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

Update the MIPS main loop code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn

(We already handle TARGET_QEMU_ESIGRETURN.)
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-7-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: tweak commit message; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

linux-user/main.c

@@ -2528,6 +2528,10 @@ done_syscall:
                              env->active_tc.gpr[8], env->active_tc.gpr[9],
                              env->active_tc.gpr[10], env->active_tc.gpr[11]);
 # endif /* O32 */
+            if (ret == -TARGET_ERESTARTSYS) {
+                env->active_tc.PC -= 4;
+                break;
+            }
             if (ret == -TARGET_QEMU_ESIGRETURN) {
                 /* Returning from a successful sigreturn syscall.
                    Avoid clobbering register state.  */

linux-user/mips/target_signal.h

@@ -26,4 +26,5 @@ static inline abi_ulong get_sp_from_cpustate(CPUMIPSState *state)
     return state->active_tc.gpr[29];
 }
 
+
 #endif /* TARGET_SIGNAL_H */

linux-user/mips64/target_signal.h

@@ -26,4 +26,5 @@ static inline abi_ulong get_sp_from_cpustate(CPUMIPSState *state)
     return state->active_tc.gpr[29];
 }
 
+
 #endif /* TARGET_SIGNAL_H */