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 // 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