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Add custom getcontext() implementation for Android.

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This adds a minimalistic implementation of getcontext()
for Android/ARM and Android/x86. The provided code is
in assembly and only implements the bare minimum required
by Breakpad to get the current processor state.

Note that:

- The FPU state is not saved to the ucontext_t on ARM.
  (that's actually the main difference with a normal
   getcontext() implementation).

  This is normal. On Linux/ARM, such state must be
  obtained with PTRACE_GETVFPREGS instead. This will
  be implemented in a future patch.

- On x86, only the 'regular' FPU state is saved, to
  mimic the GLibc/i386 implementation. The state of
  SSE/SSE2/etc registers is not part of the upstream
  getcontext() implementation.
Review URL: https://breakpad.appspot.com/444002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1024 4c0a9323-5329-0410-9bdc-e9ce6186880e
This commit is contained in:
digit@chromium.org 2012-08-31 18:38:29 +00:00
parent fa064e215b
commit 7e3c538af1
12 changed files with 1354 additions and 95 deletions
Download patch file Download diff file Expand all files Collapse all files

12
src/client/linux/handler/exception_handler.cc
View file

@ -324,16 +324,11 @@ bool ExceptionHandler::HandleSignal(int sig, siginfo_t* info, void* uc) {
// This is a public interface to HandleSignal that allows the client to
// generate a crash dump. This function may run in a compromised context.
bool ExceptionHandler::SimulateSignalDelivery(int sig) {
#ifdef __ANDROID__
// Android doesn't provide getcontext().
return false;
#else
siginfo_t siginfo;
my_memset(&siginfo, 0, sizeof(siginfo_t));
struct ucontext context;
getcontext(&context);
return HandleSignal(sig, &siginfo, &context);
#endif
}
// This function may run in a compromised context: see the top of the file.
@ -457,7 +452,6 @@ bool ExceptionHandler::WriteMinidump(const string& dump_path,
}
bool ExceptionHandler::WriteMinidump() {
#if !defined(__ARM_EABI__) && !defined(__ANDROID__)
if (!IsOutOfProcess() && !minidump_descriptor_.IsFD()) {
// Update the path of the minidump so that this can be called multiple times
// and new files are created for each minidump. This is done before the
@ -478,14 +472,14 @@ bool ExceptionHandler::WriteMinidump() {
int getcontext_result = getcontext(&context.context);
if (getcontext_result)
return false;
#if !defined(__ARM_EABI__)
// FPU state is not part of ARM EABI ucontext_t.
memcpy(&context.float_state, context.context.uc_mcontext.fpregs,
sizeof(context.float_state));
#endif
context.tid = sys_gettid();
return GenerateDump(&context);
#else
return false;
#endif // !defined(__ARM_EABI__) && !defined(__ANDROID__)
}
void ExceptionHandler::AddMappingInfo(const string& name,

145
src/common/android/breakpad_getcontext.S Normal file
View file

@ -0,0 +1,145 @@
// Copyright (c) 2012, Google Inc.
// 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.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// 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.
// A minimalistic implementation of getcontext() to be used by
// Google Breakpad on Android.
#include "common/android/ucontext_constants.h"
/* int getcontext (ucontext_t *ucp) */
#ifdef __arm__
.text
.global breakpad_getcontext
.hidden breakpad_getcontext
.type breakpad_getcontext, #function
.align 0
.fnstart
breakpad_getcontext:
/* First, save r4-r11 */
add r1, r0, #(MCONTEXT_GREGS_OFFSET + 4*4)
stm r1, {r4-r11}
/* r12 is a scratch register, don't save it */
/* Save sp and lr explicitely. */
/* - sp can't be stored with stmia in Thumb-2 */
/* - STM instructions that store sp and pc are deprecated in ARM */
str sp, [r0, #(MCONTEXT_GREGS_OFFSET + 13*4)]
str lr, [r0, #(MCONTEXT_GREGS_OFFSET + 14*4)]
/* Save the caller's address in 'pc' */
str lr, [r0, #(MCONTEXT_GREGS_OFFSET + 15*4)]
/* Save ucontext_t* pointer accross next call */
mov r4, r0
/* Call sigprocmask(SIG_BLOCK, NULL, &(ucontext->uc_sigmask)) */
mov r0, #0 /* SIG_BLOCK */
mov r1, #0 /* NULL */
add r2, r4, #UCONTEXT_SIGMASK_OFFSET
bl sigprocmask(PLT)
/* Intentionally do not save the FPU state here. This is because on
* Linux/ARM, one should instead use ptrace(PTRACE_GETFPREGS) or
* ptrace(PTRACE_GETVFPREGS) to get it.
*
* Note that a real implementation of getcontext() would need to save
* this here to allow setcontext()/swapcontext() to work correctly.
*/
/* Restore the values of r4 and lr */
mov r0, r4
ldr lr, [r0, #(MCONTEXT_GREGS_OFFSET + 14*4)]
ldr r4, [r0, #(MCONTEXT_GREGS_OFFSET + 4*4)]
/* Return 0 */
mov r0, #0
bx lr
.fnend
.size breakpad_getcontext, . - breakpad_getcontext
#elif defined(__i386__)
.text
.global breakpad_getcontext
.hidden breakpad_getcontext
.align 4
.type breakpad_getcontext, @function
breakpad_getcontext:
movl 4(%esp), %eax /* eax = uc */
/* Save register values */
movl %ecx, MCONTEXT_ECX_OFFSET(%eax)
movl %edx, MCONTEXT_EDX_OFFSET(%eax)
movl %ebx, MCONTEXT_EBX_OFFSET(%eax)
movl %edi, MCONTEXT_EDI_OFFSET(%eax)
movl %esi, MCONTEXT_ESI_OFFSET(%eax)
movl %ebp, MCONTEXT_EBP_OFFSET(%eax)
movl (%esp), %edx /* return address */
lea 4(%esp), %ecx /* exclude return address from stack */
mov %edx, MCONTEXT_EIP_OFFSET(%eax)
mov %ecx, MCONTEXT_ESP_OFFSET(%eax)
xorl %ecx, %ecx
movw %fs, %cx
mov %ecx, MCONTEXT_FS_OFFSET(%eax)
movl $0, MCONTEXT_EAX_OFFSET(%eax)
/* Save floating point state to fpregstate, then update
* the fpregs pointer to point to it */
leal UCONTEXT_FPREGS_MEM_OFFSET(%eax), %ecx
fnstenv (%ecx)
fldenv (%ecx)
mov %ecx, UCONTEXT_FPREGS_OFFSET(%eax)
/* Save signal mask: sigprocmask(SIGBLOCK, NULL, &uc->uc_sigmask) */
leal UCONTEXT_SIGMASK_OFFSET(%eax), %edx
xorl %ecx, %ecx
push %edx /* &uc->uc_sigmask */
push %ecx /* NULL */
push %ecx /* SIGBLOCK == 0 on i386 */
call sigprocmask@PLT
addl $12, %esp
movl $0, %eax
ret
.size breakpad_getcontext, . - breakpad_getcontext
#else
#error "This file has not been ported for your CPU!"
#endif

76
src/common/android/breakpad_getcontext_unittest.cc Normal file
View file

@ -0,0 +1,76 @@
// Copyright (c) 2012, Google Inc.
// 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.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// 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 <sys/ucontext.h>
#include "breakpad_googletest_includes.h"
#include "common/android/ucontext_constants.h"
TEST(AndroidUContext, GRegsOffset) {
#ifdef __arm__
// There is no gregs[] array on ARM, so compare to the offset of
// first register fields, since they're stored in order.
ASSERT_EQ(MCONTEXT_GREGS_OFFSET, offsetof(ucontext_t,uc_mcontext.arm_r0));
#elif defined(__i386__)
ASSERT_EQ(MCONTEXT_GREGS_OFFSET, offsetof(ucontext_t,uc_mcontext.gregs));
#define CHECK_REG(x) \
ASSERT_EQ(MCONTEXT_##x##_OFFSET, \
offsetof(ucontext_t,uc_mcontext.gregs[REG_##x]))
CHECK_REG(GS);
CHECK_REG(FS);
CHECK_REG(ES);
CHECK_REG(DS);
CHECK_REG(EDI);
CHECK_REG(ESI);
CHECK_REG(EBP);
CHECK_REG(ESP);
CHECK_REG(EBX);
CHECK_REG(EDX);
CHECK_REG(ECX);
CHECK_REG(EAX);
CHECK_REG(TRAPNO);
CHECK_REG(ERR);
CHECK_REG(EIP);
CHECK_REG(CS);
CHECK_REG(EFL);
CHECK_REG(UESP);
CHECK_REG(SS);
ASSERT_EQ(UCONTEXT_FPREGS_OFFSET, offsetof(ucontext_t,uc_mcontext.fpregs));
ASSERT_EQ(UCONTEXT_FPREGS_MEM_OFFSET,
offsetof(ucontext_t,__fpregs_mem));
#else
ASSERT_EQ(MCONTEXT_GREGS_OFFSET, offsetof(ucontext_t,uc_mcontext.gregs));
#endif
}
TEST(AndroidUContext, SigmakOffset) {
ASSERT_EQ(UCONTEXT_SIGMASK_OFFSET, offsetof(ucontext_t,uc_sigmask));
}

14
src/common/android/include/sys/ucontext.h
View file

@ -50,11 +50,15 @@ extern "C" {
#include <asm/sigcontext.h>
typedef struct sigcontext mcontext_t;
// The ARM kernel uses a 64-bit signal mask.
typedef uint32_t kernel_sigmask_t[2];
typedef struct ucontext {
uint32_t uc_flags;
struct ucontext* uc_link;
stack_t uc_stack;
mcontext_t uc_mcontext;
kernel_sigmask_t uc_sigmask;
// Other fields are not used by Google Breakpad. Don't define them.
} ucontext_t;
@ -110,12 +114,16 @@ enum {
REG_SS,
};
// The i386 kernel uses a 64-bit signal mask.
typedef uint32_t kernel_sigmask_t[2];
typedef struct ucontext {
uint32_t uc_flags;
struct ucontext* uc_link;
stack_t uc_stack;
mcontext_t uc_mcontext;
// Other fields are not used by Google Breakpad. Don't define them.
kernel_sigmask_t uc_sigmask;
struct _libc_fpstate __fpregs_mem;
} ucontext_t;
#elif defined(__mips__)
@ -142,11 +150,15 @@ typedef struct {
uint32_t lo3;
} mcontext_t;
// The MIPS kernel uses a 128-bit signal mask.
typedef uint32_t kernel_sigmask_t[4];
typedef struct ucontext {
uint32_t uc_flags;
struct ucontext* uc_link;
stack_t uc_stack;
mcontext_t uc_mcontext;
kernel_sigmask_t uc_sigmask;
// Other fields are not used by Google Breakpad. Don't define them.
} ucontext_t;

25
src/common/android/include/ucontext.h
View file

@ -30,12 +30,27 @@
#ifndef GOOGLE_BREAKPAD_COMMON_ANDROID_INCLUDE_UCONTEXT_H
#define GOOGLE_BREAKPAD_COMMON_ANDROID_INCLUDE_UCONTEXT_H
#include <sys/cdefs.h>
#ifdef __BIONIC_UCONTEXT_H
#include <ucontext.h>
#else
#include <sys/ucontext.h>
// TODO: Provide a portable implementation of getcontext() then
// update ExceptionHandler::WriteMinidump() in
// src/client/linux/handler/exception_handler.cc to use it.
//
// extern int getcontext(ucontext_t* ucp);
#ifdef __cplusplus
extern "C" {
#endif // __cplusplus
// Provided by src/android/common/breakpad_getcontext.S
int breakpad_getcontext(ucontext_t* ucp);
#define getcontext(x) breakpad_getcontext(x)
#ifdef __cplusplus
} // extern "C"
#endif // __cplusplus
#endif // __BIONIC_UCONTEXT_H
#endif // GOOGLE_BREAKPAD_COMMON_ANDROID_INCLUDE_UCONTEXT_H

85
src/common/android/ucontext_constants.h Normal file
View file

@ -0,0 +1,85 @@
// Copyright (c) 2012, Google Inc.
// 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.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// 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.
// This header can be included either from a C, C++ or Assembly file.
// Its purpose is to contain constants that must match the offsets of
// various fields in ucontext_t.
//
// They should match the definitions from
// src/common/android/include/sys/ucontext.h
//
// Used by src/common/android/breakpad_getcontext.S
// Tested by src/common/android/testing/breakpad_getcontext_unittest.cc
#ifndef GOOGLEBREAKPAD_COMMON_ANDROID_UCONTEXT_CONSTANTS_H
#define GOOGLEBREAKPAD_COMMON_ANDROID_UCONTEXT_CONSTANTS_H
#if defined(__arm__)
#define MCONTEXT_GREGS_OFFSET 32
#define UCONTEXT_SIGMASK_OFFSET 104
#elif defined(__i386__)
#define MCONTEXT_GREGS_OFFSET 20
#define MCONTEXT_GS_OFFSET (MCONTEXT_GREGS_OFFSET + 0*4)
#define MCONTEXT_FS_OFFSET (MCONTEXT_GREGS_OFFSET + 1*4)
#define MCONTEXT_ES_OFFSET (MCONTEXT_GREGS_OFFSET + 2*4)
#define MCONTEXT_DS_OFFSET (MCONTEXT_GREGS_OFFSET + 3*4)
#define MCONTEXT_EDI_OFFSET (MCONTEXT_GREGS_OFFSET + 4*4)
#define MCONTEXT_ESI_OFFSET (MCONTEXT_GREGS_OFFSET + 5*4)
#define MCONTEXT_EBP_OFFSET (MCONTEXT_GREGS_OFFSET + 6*4)
#define MCONTEXT_ESP_OFFSET (MCONTEXT_GREGS_OFFSET + 7*4)
#define MCONTEXT_EBX_OFFSET (MCONTEXT_GREGS_OFFSET + 8*4)
#define MCONTEXT_EDX_OFFSET (MCONTEXT_GREGS_OFFSET + 9*4)
#define MCONTEXT_ECX_OFFSET (MCONTEXT_GREGS_OFFSET + 10*4)
#define MCONTEXT_EAX_OFFSET (MCONTEXT_GREGS_OFFSET + 11*4)
#define MCONTEXT_TRAPNO_OFFSET (MCONTEXT_GREGS_OFFSET + 12*4)
#define MCONTEXT_ERR_OFFSET (MCONTEXT_GREGS_OFFSET + 13*4)
#define MCONTEXT_EIP_OFFSET (MCONTEXT_GREGS_OFFSET + 14*4)
#define MCONTEXT_CS_OFFSET (MCONTEXT_GREGS_OFFSET + 15*4)
#define MCONTEXT_EFL_OFFSET (MCONTEXT_GREGS_OFFSET + 16*4)
#define MCONTEXT_UESP_OFFSET (MCONTEXT_GREGS_OFFSET + 17*4)
#define MCONTEXT_SS_OFFSET (MCONTEXT_GREGS_OFFSET + 18*4)
#define UCONTEXT_SIGMASK_OFFSET 108
#define UCONTEXT_FPREGS_OFFSET 96
#define UCONTEXT_FPREGS_MEM_OFFSET 116
#elif defined(__mips__)
#define MCONTEXT_GREGS_OFFSET 0
#define UCONTEXT_SIGMASK_OFFSET 0
#else
#error "This header has not been ported for your CPU"
#endif
#endif // GOOGLEBREAKPAD_COMMON_ANDROID_UCONTEXT_CONSTANTS_H