From 7e3c538af1bdee7f5a4c04e11715488f1d4efd15 Mon Sep 17 00:00:00 2001 From: "digit@chromium.org" Date: Fri, 31 Aug 2012 18:38:29 +0000 Subject: Add custom getcontext() implementation for Android. 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 --- src/common/android/breakpad_getcontext.S | 145 +++++++++++++++++++++++++++++++ 1 file changed, 145 insertions(+) create mode 100644 src/common/android/breakpad_getcontext.S (limited to 'src/common/android/breakpad_getcontext.S') diff --git a/src/common/android/breakpad_getcontext.S b/src/common/android/breakpad_getcontext.S new file mode 100644 index 00000000..13ccd46b --- /dev/null +++ b/src/common/android/breakpad_getcontext.S @@ -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 -- cgit v1.2.1