linux-user: Support for restarting system calls for UniCore32 targets

Update the UniCore32 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 support signals on this target so there is no sigreturn code
to update.)

Signed-off-by: Timothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-30-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 cc7f2aa..9e6448a 100644 (file)
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -1171,7 +1171,7 @@ void cpu_loop(CPUUniCore32State *env)
                             cpu_set_tls(env, env->regs[0]);
                             env->regs[0] = 0;
                     } else {
-                        env->regs[0] = do_syscall(env,
+                        abi_long ret = do_syscall(env,
                                                   n,
                                                   env->regs[0],
                                                   env->regs[1],
@@ -1180,6 +1180,11 @@ void cpu_loop(CPUUniCore32State *env)
                                                   env->regs[4],
                                                   env->regs[5],
                                                   0, 0);
+                        if (ret == -TARGET_ERESTARTSYS) {
+                            env->regs[31] -= 4;
+                        } else if (ret != -TARGET_QEMU_ESIGRETURN) {
+                            env->regs[0] = ret;
+                        }
                     }
                 } else {
                     goto error;