linux-user/sh4: Implement setup_sigtramp

Create and record the two signal trampolines.
Use them when the guest does not use SA_RESTORER.

Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210929130553.121567-23-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

2 files changed, 24 insertions, 18 deletions

diff --git a/linux-user/sh4/signal.c b/linux-user/sh4/signal.c
index d70d744..faa869f 100644
--- a/linux-user/sh4/signal.c
+++ b/linux-user/sh4/signal.c
@@ -52,7 +52,6 @@ struct target_sigframe
 {
     struct target_sigcontext sc;
     target_ulong extramask[TARGET_NSIG_WORDS-1];
-    uint16_t retcode[3];
 };
 
 
@@ -68,7 +67,6 @@ struct target_rt_sigframe
 {
     struct target_siginfo info;
     struct target_ucontext uc;
-    uint16_t retcode[3];
 };
 
 
@@ -190,15 +188,9 @@ void setup_frame(int sig, struct target_sigaction *ka,
     /* Set up to return from userspace.  If provided, use a stub
        already in userspace.  */
     if (ka->sa_flags & TARGET_SA_RESTORER) {
-        regs->pr = (unsigned long) ka->sa_restorer;
+        regs->pr = ka->sa_restorer;
     } else {
-        /* Generate return code (system call to sigreturn) */
-        abi_ulong retcode_addr = frame_addr +
-                                 offsetof(struct target_sigframe, retcode);
-        __put_user(MOVW(2), &frame->retcode[0]);
-        __put_user(TRAP_NOARG, &frame->retcode[1]);
-        __put_user((TARGET_NR_sigreturn), &frame->retcode[2]);
-        regs->pr = (unsigned long) retcode_addr;
+        regs->pr = default_sigreturn;
     }
 
     /* Set up registers for signal handler */
@@ -248,15 +240,9 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
     /* Set up to return from userspace.  If provided, use a stub
        already in userspace.  */
     if (ka->sa_flags & TARGET_SA_RESTORER) {
-        regs->pr = (unsigned long) ka->sa_restorer;
+        regs->pr = ka->sa_restorer;
     } else {
-        /* Generate return code (system call to sigreturn) */
-        abi_ulong retcode_addr = frame_addr +
-                                 offsetof(struct target_rt_sigframe, retcode);
-        __put_user(MOVW(2), &frame->retcode[0]);
-        __put_user(TRAP_NOARG, &frame->retcode[1]);
-        __put_user((TARGET_NR_rt_sigreturn), &frame->retcode[2]);
-        regs->pr = (unsigned long) retcode_addr;
+        regs->pr = default_rt_sigreturn;
     }
 
     /* Set up registers for signal handler */
@@ -334,3 +320,21 @@ badframe:
     force_sig(TARGET_SIGSEGV);
     return -TARGET_QEMU_ESIGRETURN;
 }
+
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    uint16_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 2 * 6, 0);
+    assert(tramp != NULL);
+
+    default_sigreturn = sigtramp_page;
+    __put_user(MOVW(2), &tramp[0]);
+    __put_user(TRAP_NOARG, &tramp[1]);
+    __put_user(TARGET_NR_sigreturn, &tramp[2]);
+
+    default_rt_sigreturn = sigtramp_page + 6;
+    __put_user(MOVW(2), &tramp[3]);
+    __put_user(TRAP_NOARG, &tramp[4]);
+    __put_user(TARGET_NR_rt_sigreturn, &tramp[5]);
+
+    unlock_user(tramp, sigtramp_page, 2 * 6);
+}
diff --git a/linux-user/sh4/target_signal.h b/linux-user/sh4/target_signal.h
index d7309b7..04069cb 100644
--- a/linux-user/sh4/target_signal.h
+++ b/linux-user/sh4/target_signal.h
@@ -22,4 +22,6 @@ typedef struct target_sigaltstack {
 #include "../generic/signal.h"
 
 #define TARGET_ARCH_HAS_SETUP_FRAME
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
+
 #endif /* SH4_TARGET_SIGNAL_H */