From 8f8308c974169d7b9909db361e14cd257d47b2a7 Mon Sep 17 00:00:00 2001
From: Christopher Ferris <cferris@google.com>
Date: Wed, 30 Sep 2015 15:32:15 -0700
Subject: [PATCH] Add a no dwarf version of assembler macros.

For the __release and __release_rt functions, the previous macros
would add a dwarf cfi entry for the function with no values. This works
with libunwind since it always tries the arm unwind information first.

This change removes those entries by creating a no dwarf version of the
assembler macro.

Change-Id: Ib93e42fff5a79b8d770eab0071fdee7d2afa988d
---
 libc/arch-arm/bionic/__restore.S | 12 +++++++-----
 libc/private/bionic_asm.h        | 17 ++++++++++++++---
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/libc/arch-arm/bionic/__restore.S b/libc/arch-arm/bionic/__restore.S
index 98981256b..8c1e41d53 100644
--- a/libc/arch-arm/bionic/__restore.S
+++ b/libc/arch-arm/bionic/__restore.S
@@ -34,7 +34,9 @@
 // __restore_rt (but covered by the .fnstart/.fnend) so that although they're
 // not inside the functions from objdump's point of view, an unwinder that
 // blindly looks at the previous instruction (but is then smart enough to check
-// the DWARF information to find out where it landed) gets the right answer.
+// the unwind information to find out where it landed) gets the right answer.
+// Make sure not to have both DWARF and ARM unwind information, so only
+// use the ARM unwind information.
 
 // We need to place .fnstart ourselves (but we may as well keep the free .fnend).
 #undef __bionic_asm_custom_entry
@@ -44,18 +46,18 @@
   .save {r0-r15}
   .pad #32
   nop
-ENTRY_PRIVATE(__restore)
+ENTRY_PRIVATE_NO_DWARF(__restore)
   // This function must have exactly this instruction sequence.
   mov r7, #__NR_sigreturn
   swi #0
-END(__restore)
+END_NO_DWARF(__restore)
 
   .fnstart
   .save {r0-r15}
   .pad #160
   nop
-ENTRY_PRIVATE(__restore_rt)
+ENTRY_PRIVATE_NO_DWARF(__restore_rt)
   // This function must have exactly this instruction sequence.
   mov r7, #__NR_rt_sigreturn
   swi #0
-END(__restore_rt)
+END_NO_DWARF(__restore_rt)
diff --git a/libc/private/bionic_asm.h b/libc/private/bionic_asm.h
index 5fca222c4..e2084d438 100644
--- a/libc/private/bionic_asm.h
+++ b/libc/private/bionic_asm.h
@@ -38,25 +38,36 @@
 
 #include <machine/asm.h>
 
-#define ENTRY(f) \
+#define ENTRY_NO_DWARF(f) \
     .text; \
     .globl f; \
     .align __bionic_asm_align; \
     .type f, __bionic_asm_function_type; \
     f: \
     __bionic_asm_custom_entry(f); \
+
+#define ENTRY(f) \
+    ENTRY_NO_DWARF(f) \
     .cfi_startproc \
 
+#define END_NO_DWARF(f) \
+    .size f, .-f; \
+    __bionic_asm_custom_end(f) \
+
 #define END(f) \
     .cfi_endproc; \
-    .size f, .-f; \
-    __bionic_asm_custom_end(f) \
+    END_NO_DWARF(f) \
 
 /* Like ENTRY, but with hidden visibility. */
 #define ENTRY_PRIVATE(f) \
     ENTRY(f); \
     .hidden f \
 
+/* Like ENTRY_NO_DWARF, but with hidden visibility. */
+#define ENTRY_PRIVATE_NO_DWARF(f) \
+    ENTRY_NO_DWARF(f); \
+    .hidden f \
+
 #define ALIAS_SYMBOL(alias, original) \
     .globl alias; \
     .equ alias, original