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
(cherry picked from commit 1cff9a89645a8f362a9ce19c7f9544e98c1fd9e7)
Change-Id: Ie13d73fd97395e1979a67c2294e036a97c50000d
diff --git a/libc/bionic/sigaction.cpp b/libc/bionic/sigaction.cpp
index 8ba4e2a..9038bd5 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;
@@ -64,7 +67,7 @@
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;
if (bionic_old_action->sa_restorer == &__rt_sigreturn) {
@@ -74,15 +77,21 @@
}
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)) {
@@ -92,5 +101,6 @@
#endif
}
return __sigaction(signal, (bionic_new_action != NULL) ? &kernel_new_action : NULL, bionic_old_action);
-#endif
}
+
+#endif