linux-user/alpha: Implement setup_sigtramp

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

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210929130553.121567-7-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

1 files changed, 20 insertions, 14 deletions

diff --git a/linux-user/alpha/signal.c b/linux-user/alpha/signal.c
index 3a820f6..bbe3dd1 100644
--- a/linux-user/alpha/signal.c
+++ b/linux-user/alpha/signal.c
@@ -55,13 +55,11 @@ struct target_ucontext {
 
 struct target_sigframe {
     struct target_sigcontext sc;
-    unsigned int retcode[3];
 };
 
 struct target_rt_sigframe {
     target_siginfo_t info;
     struct target_ucontext uc;
-    unsigned int retcode[3];
 };
 
 #define INSN_MOV_R30_R16        0x47fe0410
@@ -142,12 +140,7 @@ void setup_frame(int sig, struct target_sigaction *ka,
     if (ka->ka_restorer) {
         r26 = ka->ka_restorer;
     } else {
-        __put_user(INSN_MOV_R30_R16, &frame->retcode[0]);
-        __put_user(INSN_LDI_R0 + TARGET_NR_sigreturn,
-                   &frame->retcode[1]);
-        __put_user(INSN_CALLSYS, &frame->retcode[2]);
-        /* imb() */
-        r26 = frame_addr + offsetof(struct target_sigframe, retcode);
+        r26 = default_sigreturn;
     }
 
     unlock_user_struct(frame, frame_addr, 1);
@@ -196,12 +189,7 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
     if (ka->ka_restorer) {
         r26 = ka->ka_restorer;
     } else {
-        __put_user(INSN_MOV_R30_R16, &frame->retcode[0]);
-        __put_user(INSN_LDI_R0 + TARGET_NR_rt_sigreturn,
-                   &frame->retcode[1]);
-        __put_user(INSN_CALLSYS, &frame->retcode[2]);
-        /* imb(); */
-        r26 = frame_addr + offsetof(struct target_rt_sigframe, retcode);
+        r26 = default_rt_sigreturn;
     }
 
     if (err) {
@@ -269,3 +257,21 @@ badframe:
     force_sig(TARGET_SIGSEGV);
     return -TARGET_QEMU_ESIGRETURN;
 }
+
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 6 * 4, 0);
+    assert(tramp != NULL);
+
+    default_sigreturn = sigtramp_page;
+    __put_user(INSN_MOV_R30_R16, &tramp[0]);
+    __put_user(INSN_LDI_R0 + TARGET_NR_sigreturn, &tramp[1]);
+    __put_user(INSN_CALLSYS, &tramp[2]);
+
+    default_rt_sigreturn = sigtramp_page + 3 * 4;
+    __put_user(INSN_MOV_R30_R16, &tramp[3]);
+    __put_user(INSN_LDI_R0 + TARGET_NR_rt_sigreturn, &tramp[4]);
+    __put_user(INSN_CALLSYS, &tramp[5]);
+
+    unlock_user(tramp, sigtramp_page, 6 * 4);
+}