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-x86/bionic/__restore.S b/libc/arch-x86/bionic/__restore.S
new file mode 100644
index 0000000..755c3f8
--- /dev/null
+++ b/libc/arch-x86/bionic/__restore.S
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2014 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.
+// This function must have exactly this name for gdb.
+ENTRY(__restore)
+ popl %eax
+ movl $__NR_sigreturn, %eax
+ int $0x80
+END(__restore)
diff --git a/libc/arch-x86/bionic/__restore_rt.S b/libc/arch-x86/bionic/__restore_rt.S
new file mode 100644
index 0000000..0cd8081
--- /dev/null
+++ b/libc/arch-x86/bionic/__restore_rt.S
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2014 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.
+// This function must have exactly this name for gdb.
+ENTRY(__restore_rt)
+ movl $__NR_rt_sigreturn, %eax
+ int $0x80
+END(__restore_rt)
diff --git a/libc/arch-x86/x86.mk b/libc/arch-x86/x86.mk
index a141548..f45eb65 100644
--- a/libc/arch-x86/x86.mk
+++ b/libc/arch-x86/x86.mk
@@ -25,6 +25,8 @@
libc_bionic_src_files_x86 += \
arch-x86/bionic/__bionic_clone.S \
arch-x86/bionic/_exit_with_stack_teardown.S \
+ arch-x86/bionic/__restore_rt.S \
+ arch-x86/bionic/__restore.S \
arch-x86/bionic/_setjmp.S \
arch-x86/bionic/setjmp.S \
arch-x86/bionic/__set_tls.c \