[PULL 12/26] linux-user/m68k: Implement setup_sigtramp

[Laurent Vivier <laurent@vivier.eu>]

From: Richard Henderson <richard.henderson@linaro.org>

Create and record the two signal trampolines.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210929130553.121567-13-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/m68k/signal.c        | 47 +++++++++++++++------------------
 linux-user/m68k/target_signal.h |  2 ++
 2 files changed, 24 insertions(+), 25 deletions(-)

diff --git a/linux-user/m68k/signal.c b/linux-user/m68k/signal.c
index 4f8eb6f727e4..ec33482e1403 100644
--- a/linux-user/m68k/signal.c
+++ b/linux-user/m68k/signal.c
@@ -39,7 +39,6 @@ struct target_sigframe
     int sig;
     int code;
     abi_ulong psc;
-    char retcode[8];
     abi_ulong extramask[TARGET_NSIG_WORDS-1];
     struct target_sigcontext sc;
 };
@@ -76,7 +75,6 @@ struct target_rt_sigframe
     int sig;
     abi_ulong pinfo;
     abi_ulong puc;
-    char retcode[8];
     struct target_siginfo info;
     struct target_ucontext uc;
 };
@@ -130,7 +128,6 @@ void setup_frame(int sig, struct target_sigaction *ka,
 {
     struct target_sigframe *frame;
     abi_ulong frame_addr;
-    abi_ulong retcode_addr;
     abi_ulong sc_addr;
     int i;
 
@@ -152,16 +149,7 @@ void setup_frame(int sig, struct target_sigaction *ka,
     }
 
     /* Set up to return from userspace.  */
-
-    retcode_addr = frame_addr + offsetof(struct target_sigframe, retcode);
-    __put_user(retcode_addr, &frame->pretcode);
-
-    /* moveq #,d0; trap #0 */
-
-    __put_user(0x70004e40 + (TARGET_NR_sigreturn << 16),
-               (uint32_t *)(frame->retcode));
-
-    /* Set up to return from userspace */
+    __put_user(default_sigreturn, &frame->pretcode);
 
     env->aregs[7] = frame_addr;
     env->pc = ka->_sa_handler;
@@ -288,7 +276,6 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
 {
     struct target_rt_sigframe *frame;
     abi_ulong frame_addr;
-    abi_ulong retcode_addr;
     abi_ulong info_addr;
     abi_ulong uc_addr;
     int err = 0;
@@ -325,17 +312,7 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
     }
 
     /* Set up to return from userspace.  */
-
-    retcode_addr = frame_addr + offsetof(struct target_sigframe, retcode);
-    __put_user(retcode_addr, &frame->pretcode);
-
-    /* moveq #,d0; notb d0; trap #0 */
-
-    __put_user(0x70004600 + ((TARGET_NR_rt_sigreturn ^ 0xff) << 16),
-               (uint32_t *)(frame->retcode + 0));
-    __put_user(0x4e40, (uint16_t *)(frame->retcode + 4));
-
-    /* Set up to return from userspace */
+    __put_user(default_rt_sigreturn, &frame->pretcode);
 
     env->aregs[7] = frame_addr;
     env->pc = ka->_sa_handler;
@@ -411,3 +388,23 @@ badframe:
     force_sig(TARGET_SIGSEGV);
     return -TARGET_QEMU_ESIGRETURN;
 }
+
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    void *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 4 + 6, 0);
+    assert(tramp != NULL);
+
+    default_sigreturn = sigtramp_page;
+
+    /* moveq #,d0; trap #0 */
+    __put_user(0x70004e40 + (TARGET_NR_sigreturn << 16), (uint32_t *)tramp);
+
+    default_rt_sigreturn = sigtramp_page + 4;
+
+    /* moveq #,d0; notb d0; trap #0 */
+    __put_user(0x70004600 + ((TARGET_NR_rt_sigreturn ^ 0xff) << 16),
+               (uint32_t *)(tramp + 4));
+    __put_user(0x4e40, (uint16_t *)(tramp + 8));
+
+    unlock_user(tramp, sigtramp_page, 4 + 6);
+}
diff --git a/linux-user/m68k/target_signal.h b/linux-user/m68k/target_signal.h
index d096544ef842..94157bf1f48d 100644
--- a/linux-user/m68k/target_signal.h
+++ b/linux-user/m68k/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 /* M68K_TARGET_SIGNAL_H */
-- 
2.31.1