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Fix 32-bit arm unwinding through signal frames.

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gdb was already okay; libgcc and libunwind need a little extra help.

Bug: 17436734

(cherry picked from commit 148dff3ec6)

Change-Id: I2cc997017acc57c930284af5264f353656b98c7b
This commit is contained in:
Elliott Hughes 2014-09-16 13:57:39 -07:00
parent 7dc2b7b30d
commit 5054e1a121
3 changed files with 27 additions and 37 deletions
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1
libc/arch-arm/arm.mk
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@ -55,7 +55,6 @@ libc_bionic_src_files_arm += \
arch-arm/bionic/_exit_with_stack_teardown.S \
arch-arm/bionic/libgcc_compat.c \
arch-arm/bionic/memcmp.S \
arch-arm/bionic/__restore_rt.S \
arch-arm/bionic/__restore.S \
arch-arm/bionic/_setjmp.S \
arch-arm/bionic/setjmp.S \

28
libc/arch-arm/bionic/__restore.S
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@ -28,8 +28,34 @@
#include <private/bionic_asm.h>
// This function must have exactly this instruction sequence for gdb and libunwind.
// gdb is smart enough to unwind through signal frames with just the regular
// CFI information but libgcc and libunwind both need extra help. We do this
// by using .fnstart/.fnend and inserting a nop before both __restore and
// __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.
// We need to place .fnstart ourselves (but we may as well keep the free .fnend).
#undef __bionic_asm_custom_entry
#define __bionic_asm_custom_entry(f)
.fnstart
.save {r0-r15}
.pad #32
nop
ENTRY_PRIVATE(__restore)
// This function must have exactly this instruction sequence.
mov r7, #__NR_sigreturn
swi #0
END(__restore)
.fnstart
.save {r0-r15}
.pad #160
nop
ENTRY_PRIVATE(__restore_rt)
// This function must have exactly this instruction sequence.
mov r7, #__NR_rt_sigreturn
swi #0
END(__restore_rt)

35
libc/arch-arm/bionic/__restore_rt.S
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@ -1,35 +0,0 @@
/*
* 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.
ENTRY_PRIVATE(__restore_rt)
mov r7, #__NR_rt_sigreturn
swi #0
END(__restore_rt)