[PATCH v2 02/23] linux-user/aarch64: Implement setup_sigtramp

[Richard Henderson]

Create and record the rt signal trampoline.
Use it when the guest does not use SA_RESTORER.

Cc: qemu-arm@nongnu.org
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/aarch64/target_signal.h |  2 ++
 linux-user/aarch64/signal.c        | 28 ++++++++++++++++++----------
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/linux-user/aarch64/target_signal.h 
b/linux-user/aarch64/target_signal.h
index 18013e1b23..7580d99403 100644
--- a/linux-user/aarch64/target_signal.h
+++ b/linux-user/aarch64/target_signal.h
@@ -25,4 +25,6 @@ typedef struct target_sigaltstack {
 #define TARGET_SEGV_MTESERR  9  /* Synchronous ARM MTE exception */
 
 #define TARGET_ARCH_HAS_SETUP_FRAME
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
+
 #endif /* AARCH64_TARGET_SIGNAL_H */
diff --git a/linux-user/aarch64/signal.c b/linux-user/aarch64/signal.c
index 662bcd1c4e..65b84eb04e 100644
--- a/linux-user/aarch64/signal.c
+++ b/linux-user/aarch64/signal.c
@@ -108,7 +108,6 @@ struct target_rt_sigframe {
 struct target_rt_frame_record {
     uint64_t fp;
     uint64_t lr;
-    uint32_t tramp[2];
 };
 
 static void target_setup_general_frame(struct target_rt_sigframe *sf,
@@ -495,15 +494,7 @@ static void target_setup_frame(int usig, struct 
target_sigaction *ka,
     if (ka->sa_flags & TARGET_SA_RESTORER) {
         return_addr = ka->sa_restorer;
     } else {
-        /*
-         * mov x8,#__NR_rt_sigreturn; svc #0
-         * Since these are instructions they need to be put as little-endian
-         * regardless of target default or current CPU endianness.
-         */
-        __put_user_e(0xd2801168, &fr->tramp[0], le);
-        __put_user_e(0xd4000001, &fr->tramp[1], le);
-        return_addr = frame_addr + fr_ofs
-            + offsetof(struct target_rt_frame_record, tramp);
+        return_addr = default_rt_sigreturn;
     }
     env->xregs[0] = usig;
     env->xregs[29] = frame_addr + fr_ofs;
@@ -576,3 +567,20 @@ long do_sigreturn(CPUARMState *env)
 {
     return do_rt_sigreturn(env);
 }
+
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 8, 0);
+    assert(tramp != NULL);
+
+    /*
+     * mov x8,#__NR_rt_sigreturn; svc #0
+     * Since these are instructions they need to be put as little-endian
+     * regardless of target default or current CPU endianness.
+     */
+    __put_user_e(0xd2801168, &tramp[0], le);
+    __put_user_e(0xd4000001, &tramp[1], le);
+
+    default_rt_sigreturn = sigtramp_page;
+    unlock_user(tramp, sigtramp_page, 8);
+}
-- 
2.25.1