Use the kernel's sa_restorer for aarch64.
gdb was happy with what we had, but libgcc and libunwind weren't.
libgcc is happy with the kernel's restorer (because of the extra nop),
though libunwind looks like it's going to need code changes regardless.
We could make our restorer more like the kernel's one, but why bother
when we can just let the kernel supply the canonical one?
Bug: 17436734
Change-Id: I330fa5e68f23b1cf8133aa552896657b0b873ed3
diff --git a/libc/arch-arm64/arm64.mk b/libc/arch-arm64/arm64.mk
index 91cd9fb..eb65cfd 100644
--- a/libc/arch-arm64/arm64.mk
+++ b/libc/arch-arm64/arm64.mk
@@ -29,7 +29,6 @@
libc_bionic_src_files_arm64 := \
arch-arm64/bionic/__bionic_clone.S \
arch-arm64/bionic/_exit_with_stack_teardown.S \
- arch-arm64/bionic/__restore_rt.S \
arch-arm64/bionic/_setjmp.S \
arch-arm64/bionic/setjmp.S \
arch-arm64/bionic/__set_tls.c \
diff --git a/libc/arch-arm64/bionic/__restore_rt.S b/libc/arch-arm64/bionic/__restore_rt.S
deleted file mode 100644
index 9506490..0000000
--- a/libc/arch-arm64/bionic/__restore_rt.S
+++ /dev/null
@@ -1,35 +0,0 @@
-/*
- * Copyright (C) 2013 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * * Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#include <private/bionic_asm.h>
-
-// This function must have exactly this instruction sequence for gdb and libunwind.
-ENTRY_PRIVATE(__restore_rt)
- mov x8, __NR_rt_sigreturn
- svc #0
-END(__restore_rt)
diff --git a/libc/bionic/sigaction.cpp b/libc/bionic/sigaction.cpp
index 920303b..0633748 100644
--- a/libc/bionic/sigaction.cpp
+++ b/libc/bionic/sigaction.cpp
@@ -31,27 +31,30 @@
extern "C" void __restore_rt(void);
extern "C" void __restore(void);
-#if __LP64__
+#if defined(__LP64__)
+
extern "C" int __rt_sigaction(int, const struct __kernel_sigaction*, struct __kernel_sigaction*, size_t);
-#else
-extern "C" int __sigaction(int, const struct sigaction*, struct sigaction*);
-#endif
int sigaction(int signal, const struct sigaction* bionic_new_action, struct sigaction* bionic_old_action) {
-#if __LP64__
__kernel_sigaction kernel_new_action;
if (bionic_new_action != NULL) {
kernel_new_action.sa_flags = bionic_new_action->sa_flags;
kernel_new_action.sa_handler = bionic_new_action->sa_handler;
kernel_new_action.sa_mask = bionic_new_action->sa_mask;
-#ifdef SA_RESTORER
+#if defined(SA_RESTORER)
kernel_new_action.sa_restorer = bionic_new_action->sa_restorer;
-
+#if defined(__aarch64__)
+ // arm64 has sa_restorer, but unwinding works best if you just let the
+ // kernel supply the default restorer from [vdso]. gdb doesn't care, but
+ // libgcc needs the nop that the kernel includes before the actual code.
+ // (We could add that ourselves, but why bother?)
+#else
if (!(kernel_new_action.sa_flags & SA_RESTORER)) {
kernel_new_action.sa_flags |= SA_RESTORER;
kernel_new_action.sa_restorer = &__restore_rt;
}
#endif
+#endif
}
__kernel_sigaction kernel_old_action;
@@ -64,21 +67,27 @@
bionic_old_action->sa_flags = kernel_old_action.sa_flags;
bionic_old_action->sa_handler = kernel_old_action.sa_handler;
bionic_old_action->sa_mask = kernel_old_action.sa_mask;
-#ifdef SA_RESTORER
+#if defined(SA_RESTORER)
bionic_old_action->sa_restorer = kernel_old_action.sa_restorer;
#endif
}
return result;
+}
+
#else
- // The 32-bit ABI is broken. struct sigaction includes a too-small sigset_t.
- // TODO: if we also had correct struct sigaction definitions available, we could copy in and out.
+
+extern "C" int __sigaction(int, const struct sigaction*, struct sigaction*);
+
+int sigaction(int signal, const struct sigaction* bionic_new_action, struct sigaction* bionic_old_action) {
+ // The 32-bit ABI is broken. struct sigaction includes a too-small sigset_t,
+ // so we have to use sigaction(2) rather than rt_sigaction(2).
struct sigaction kernel_new_action;
if (bionic_new_action != NULL) {
kernel_new_action.sa_flags = bionic_new_action->sa_flags;
kernel_new_action.sa_handler = bionic_new_action->sa_handler;
kernel_new_action.sa_mask = bionic_new_action->sa_mask;
-#ifdef SA_RESTORER
+#if defined(SA_RESTORER)
kernel_new_action.sa_restorer = bionic_new_action->sa_restorer;
if (!(kernel_new_action.sa_flags & SA_RESTORER)) {
@@ -88,5 +97,6 @@
#endif
}
return __sigaction(signal, (bionic_new_action != NULL) ? &kernel_new_action : NULL, bionic_old_action);
-#endif
}
+
+#endif
