[PATCH v2 17/23] linux-user/ppc: Implement setup_sigtramp

From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: qemu-ppc@nongnu.org, alex.bennee@linaro.org, laurent@vivier.eu
Subject: [PATCH v2 17/23] linux-user/ppc: Implement setup_sigtramp
Date: Fri, 18 Jun 2021 12:29:45 -0700	[thread overview]
Message-ID: <20210618192951.125651-18-richard.henderson@linaro.org> (raw)
In-Reply-To: <20210618192951.125651-1-richard.henderson@linaro.org>

Create and record the two signal trampolines.

Cc: qemu-ppc@nongnu.org
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/ppc/target_signal.h |  2 ++
 linux-user/ppc/signal.c        | 34 ++++++++++++++++++----------------
 2 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/linux-user/ppc/target_signal.h b/linux-user/ppc/target_signal.h
index 72fcdd9bfa..82184ab8f2 100644
--- a/linux-user/ppc/target_signal.h
+++ b/linux-user/ppc/target_signal.h
@@ -24,4 +24,6 @@ typedef struct target_sigaltstack {
 #if !defined(TARGET_PPC64)
 #define TARGET_ARCH_HAS_SETUP_FRAME
 #endif
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
+
 #endif /* PPC_TARGET_SIGNAL_H */
diff --git a/linux-user/ppc/signal.c b/linux-user/ppc/signal.c
index edfad28a37..4ae35aaf6d 100644
--- a/linux-user/ppc/signal.c
+++ b/linux-user/ppc/signal.c
@@ -202,9 +202,6 @@ struct target_func_ptr {
 
 #endif
 
-/* We use the mc_pad field for the signal return trampoline.  */
-#define tramp mc_pad
-
 /* See arch/powerpc/kernel/signal.c.  */
 static target_ulong get_sigframe(struct target_sigaction *ka,
                                  CPUPPCState *env,
@@ -437,12 +434,7 @@ void setup_frame(int sig, struct target_sigaction *ka,
     /* Save user regs.  */
     save_user_regs(env, &frame->mctx);
 
-    /* Construct the trampoline code on the stack. */
-    encode_trampoline(TARGET_NR_sigreturn, (uint32_t *)&frame->mctx.tramp);
-
-    /* The kernel checks for the presence of a VDSO here.  We don't
-       emulate a vdso, so use a sigreturn system call.  */
-    env->lr = (target_ulong) h2g(frame->mctx.tramp);
+    env->lr = default_sigreturn;
 
     /* Turn off all fp exceptions.  */
     env->fpscr = 0;
@@ -478,7 +470,6 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
                     target_sigset_t *set, CPUPPCState *env)
 {
     struct target_rt_sigframe *rt_sf;
-    uint32_t *trampptr = 0;
     struct target_mcontext *mctx = 0;
     target_ulong rt_sf_addr, newsp = 0;
     int i, err = 0;
@@ -508,22 +499,17 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
 
 #if defined(TARGET_PPC64)
     mctx = &rt_sf->uc.tuc_sigcontext.mcontext;
-    trampptr = &rt_sf->trampoline[0];
 
     sc = &rt_sf->uc.tuc_sigcontext;
     __put_user(h2g(mctx), &sc->regs);
     __put_user(sig, &sc->signal);
 #else
     mctx = &rt_sf->uc.tuc_mcontext;
-    trampptr = (uint32_t *)&rt_sf->uc.tuc_mcontext.tramp;
 #endif
 
     save_user_regs(env, mctx);
-    encode_trampoline(TARGET_NR_rt_sigreturn, trampptr);
 
-    /* The kernel checks for the presence of a VDSO here.  We don't
-       emulate a vdso, so use a sigreturn system call.  */
-    env->lr = (target_ulong) h2g(trampptr);
+    env->lr = default_rt_sigreturn;
 
     /* Turn off all fp exceptions.  */
     env->fpscr = 0;
@@ -721,3 +707,19 @@ abi_long do_swapcontext(CPUArchState *env, abi_ulong uold_ctx,
 
     return 0;
 }
+
+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;
+    encode_trampoline(TARGET_NR_sigreturn, tramp + 0);
+#endif
+
+    default_rt_sigreturn = sigtramp_page + 8;
+    encode_trampoline(TARGET_NR_rt_sigreturn, tramp + 2);
+
+    unlock_user(tramp, sigtramp_page, 2 * 8);
+}
-- 
2.25.1


