linux-user/mips: Implement setup_sigtramp

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: <20210929130553.121567-16-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

3 files changed, 27 insertions, 10 deletions

diff --git a/linux-user/mips/signal.c b/linux-user/mips/signal.c
index 6407277..8f79e40 100644
--- a/linux-user/mips/signal.c
+++ b/linux-user/mips/signal.c
@@ -209,8 +209,6 @@ void setup_frame(int sig, struct target_sigaction * ka,
         goto give_sigsegv;
     }
 
-    install_sigtramp(frame->sf_code, TARGET_NR_sigreturn);
-
     setup_sigcontext(regs, &frame->sf_sc);
 
     for(i = 0; i < TARGET_NSIG_WORDS; i++) {
@@ -231,7 +229,7 @@ void setup_frame(int sig, struct target_sigaction * ka,
     regs->active_tc.gpr[ 5] = 0;
     regs->active_tc.gpr[ 6] = frame_addr + offsetof(struct sigframe, sf_sc);
     regs->active_tc.gpr[29] = frame_addr;
-    regs->active_tc.gpr[31] = frame_addr + offsetof(struct sigframe, sf_code);
+    regs->active_tc.gpr[31] = default_sigreturn;
     /* The original kernel code sets CP0_EPC to the handler
     * since it returns to userland using eret
     * we cannot do this here, and we must set PC directly */
@@ -305,8 +303,6 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
         goto give_sigsegv;
     }
 
-    install_sigtramp(frame->rs_code, TARGET_NR_rt_sigreturn);
-
     tswap_siginfo(&frame->rs_info, info);
 
     __put_user(0, &frame->rs_uc.tuc_flags);
@@ -335,11 +331,13 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
     env->active_tc.gpr[ 6] = frame_addr
                              + offsetof(struct target_rt_sigframe, rs_uc);
     env->active_tc.gpr[29] = frame_addr;
-    env->active_tc.gpr[31] = frame_addr
-                             + offsetof(struct target_rt_sigframe, rs_code);
-    /* The original kernel code sets CP0_EPC to the handler
-    * since it returns to userland using eret
-    * we cannot do this here, and we must set PC directly */
+    env->active_tc.gpr[31] = default_rt_sigreturn;
+
+    /*
+     * The original kernel code sets CP0_EPC to the handler
+     * since it returns to userland using eret
+     * we cannot do this here, and we must set PC directly
+     */
     env->active_tc.PC = env->active_tc.gpr[25] = ka->_sa_handler;
     mips_set_hflags_isa_mode_from_pc(env);
     unlock_user_struct(frame, frame_addr, 1);
@@ -379,3 +377,19 @@ 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, 2 * 8, 0);
+    assert(tramp != NULL);
+
+#ifdef TARGET_ARCH_HAS_SETUP_FRAME
+    default_sigreturn = sigtramp_page;
+    install_sigtramp(tramp, TARGET_NR_sigreturn);
+#endif
+
+    default_rt_sigreturn = sigtramp_page + 8;
+    install_sigtramp(tramp + 2, TARGET_NR_rt_sigreturn);
+
+    unlock_user(tramp, sigtramp_page, 2 * 8);
+}
diff --git a/linux-user/mips/target_signal.h b/linux-user/mips/target_signal.h
index d521765..780a4dd 100644
--- a/linux-user/mips/target_signal.h
+++ b/linux-user/mips/target_signal.h
@@ -73,6 +73,7 @@ typedef struct target_sigaltstack {
 /* compare linux/arch/mips/kernel/signal.c:setup_frame() */
 #define TARGET_ARCH_HAS_SETUP_FRAME
 #endif
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
 
 /* bit-flags */
 #define TARGET_SS_AUTODISARM (1U << 31) /* disable sas during sighandling */
diff --git a/linux-user/mips64/target_signal.h b/linux-user/mips64/target_signal.h
index d857c55..275e9b7 100644
--- a/linux-user/mips64/target_signal.h
+++ b/linux-user/mips64/target_signal.h
@@ -76,4 +76,6 @@ typedef struct target_sigaltstack {
 /* compare linux/arch/mips/kernel/signal.c:setup_frame() */
 #define TARGET_ARCH_HAS_SETUP_FRAME
 #endif
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
+
 #endif /* MIPS64_TARGET_SIGNAL_H */