Fix signal trampolines.
* LP32 should use sa_restorer too. gdb expects this, and future (>= 3.15) x86
kernels will apparently stop supporting the case where SA_RESTORER isn't
set.
* gdb and libunwind care about the exact instruction sequences, so we need to
modify the code slightly in a few cases to match what they're looking for.
* gdb also cares about the exact function names (for some architectures),
so we need to use __restore and __restore_rt rather than __sigreturn and
__rt_sigreturn.
* It's possible that we don't have a VDSO; dl_iterate_phdr shouldn't assume
that getauxval(AT_SYSINFO_EHDR) will return a non-null pointer.
This fixes unwinding through a signal handler in gdb for all architectures.
It doesn't fix libunwind for arm and arm64. I'll keep investigating that...
Bug: 17436734
Change-Id: Ic1ea1184db6655c5d96180dc07bcc09628e647cb
diff --git a/libc/arch-arm64/arm64.mk b/libc/arch-arm64/arm64.mk
index 6c4f6a6..91cd9fb 100644
--- a/libc/arch-arm64/arm64.mk
+++ b/libc/arch-arm64/arm64.mk
@@ -29,7 +29,7 @@
libc_bionic_src_files_arm64 := \
arch-arm64/bionic/__bionic_clone.S \
arch-arm64/bionic/_exit_with_stack_teardown.S \
- arch-arm64/bionic/__rt_sigreturn.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/__rt_sigreturn.S b/libc/arch-arm64/bionic/__restore_rt.S
similarity index 89%
rename from libc/arch-arm64/bionic/__rt_sigreturn.S
rename to libc/arch-arm64/bionic/__restore_rt.S
index 8fb6f0c..9506490 100644
--- a/libc/arch-arm64/bionic/__rt_sigreturn.S
+++ b/libc/arch-arm64/bionic/__restore_rt.S
@@ -28,7 +28,8 @@
#include <private/bionic_asm.h>
-ENTRY_PRIVATE(__rt_sigreturn)
- mov x8, __NR_rt_sigreturn
- svc #0
-END(__rt_sigreturn)
+// 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)