[PULL 23/26] linux-user/sparc: Implement setup_sigtramp

[Laurent Vivier <laurent@vivier.eu>]

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

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

Acked-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210929130553.121567-24-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/sparc/signal.c        | 40 +++++++++++++++++++++-----------
 linux-user/sparc/target_signal.h |  4 ++++
 2 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/linux-user/sparc/signal.c b/linux-user/sparc/signal.c
index 3bc023d281a7..23e1e761de42 100644
--- a/linux-user/sparc/signal.c
+++ b/linux-user/sparc/signal.c
@@ -242,6 +242,12 @@ static void restore_fpu(struct target_siginfo_fpu *fpu, CPUSPARCState *env)
 }
 
 #ifdef TARGET_ARCH_HAS_SETUP_FRAME
+static void install_sigtramp(uint32_t *tramp, int syscall)
+{
+    __put_user(0x82102000u + syscall, &tramp[0]); /* mov syscall, %g1 */
+    __put_user(0x91d02010u, &tramp[1]);           /* t 0x10 */
+}
+
 void setup_frame(int sig, struct target_sigaction *ka,
                  target_sigset_t *set, CPUSPARCState *env)
 {
@@ -291,13 +297,9 @@ void setup_frame(int sig, struct target_sigaction *ka,
     if (ka->ka_restorer) {
         env->regwptr[WREG_O7] = ka->ka_restorer;
     } else {
-        env->regwptr[WREG_O7] = sf_addr +
-                offsetof(struct target_signal_frame, insns) - 2 * 4;
-
-        /* mov __NR_sigreturn, %g1 */
-        __put_user(0x821020d8u, &sf->insns[0]);
-        /* t 0x10 */
-        __put_user(0x91d02010u, &sf->insns[1]);
+        /* Not used, but retain for ABI compatibility. */
+        install_sigtramp(sf->insns, TARGET_NR_sigreturn);
+        env->regwptr[WREG_O7] = default_sigreturn;
     }
     unlock_user(sf, sf_addr, sf_size);
 }
@@ -358,13 +360,9 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
     if (ka->ka_restorer) {
         env->regwptr[WREG_O7] = ka->ka_restorer;
     } else {
-        env->regwptr[WREG_O7] =
-            sf_addr + offsetof(struct target_rt_signal_frame, insns) - 2 * 4;
-
-        /* mov __NR_rt_sigreturn, %g1 */
-        __put_user(0x82102065u, &sf->insns[0]);
-        /* t 0x10 */
-        __put_user(0x91d02010u, &sf->insns[1]);
+        /* Not used, but retain for ABI compatibility. */
+        install_sigtramp(sf->insns, TARGET_NR_rt_sigreturn);
+        env->regwptr[WREG_O7] = default_rt_sigreturn;
     }
 #else
     env->regwptr[WREG_O7] = ka->ka_restorer;
@@ -775,4 +773,18 @@ do_sigsegv:
     unlock_user_struct(ucp, ucp_addr, 1);
     force_sig(TARGET_SIGSEGV);
 }
+#else
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 2 * 8, 0);
+    assert(tramp != NULL);
+
+    default_sigreturn = sigtramp_page;
+    install_sigtramp(tramp, TARGET_NR_sigreturn);
+
+    default_rt_sigreturn = sigtramp_page + 8;
+    install_sigtramp(tramp + 2, TARGET_NR_rt_sigreturn);
+
+    unlock_user(tramp, sigtramp_page, 2 * 8);
+}
 #endif
diff --git a/linux-user/sparc/target_signal.h b/linux-user/sparc/target_signal.h
index 34f9a1251909..e661ddd6ab3c 100644
--- a/linux-user/sparc/target_signal.h
+++ b/linux-user/sparc/target_signal.h
@@ -69,6 +69,10 @@ typedef struct target_sigaltstack {
 
 #ifdef TARGET_ABI32
 #define TARGET_ARCH_HAS_SETUP_FRAME
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
+#else
+/* For sparc64, use of KA_RESTORER is mandatory. */
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 0
 #endif
 
 /* bit-flags */
-- 
2.31.1