michael@0: // Copyright (c) 2012, Google Inc.
michael@0: // All rights reserved.
michael@0: //
michael@0: // Redistribution and use in source and binary forms, with or without
michael@0: // modification, are permitted provided that the following conditions are
michael@0: // met:
michael@0: //
michael@0: //     * Redistributions of source code must retain the above copyright
michael@0: // notice, this list of conditions and the following disclaimer.
michael@0: //     * Redistributions in binary form must reproduce the above
michael@0: // copyright notice, this list of conditions and the following disclaimer
michael@0: // in the documentation and/or other materials provided with the
michael@0: // distribution.
michael@0: //     * Neither the name of Google Inc. nor the names of its
michael@0: // contributors may be used to endorse or promote products derived from
michael@0: // this software without specific prior written permission.
michael@0: //
michael@0: // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0: // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
michael@0: // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
michael@0: // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
michael@0: // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
michael@0: // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
michael@0: // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
michael@0: // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0: // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
michael@0: // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0: 
michael@0: // A minimalistic implementation of getcontext() to be used by
michael@0: // Google Breakpad on Android.
michael@0: 
michael@0: #include "common/android/ucontext_constants.h"
michael@0: 
michael@0: /* int getcontext (ucontext_t *ucp) */
michael@0: 
michael@0: #ifdef __arm__
michael@0: 
michael@0:   .text
michael@0:   .global breakpad_getcontext
michael@0:   .hidden breakpad_getcontext
michael@0:   .type breakpad_getcontext, #function
michael@0:   .align 0
michael@0:   .fnstart
michael@0: breakpad_getcontext:
michael@0: 
michael@0:   /* First, save r4-r11 */
michael@0:   add   r1, r0, #(MCONTEXT_GREGS_OFFSET + 4*4)
michael@0:   stm   r1, {r4-r11}
michael@0: 
michael@0:   /* r12 is a scratch register, don't save it */
michael@0: 
michael@0:   /* Save sp and lr explicitely. */
michael@0:   /* - sp can't be stored with stmia in Thumb-2 */
michael@0:   /* - STM instructions that store sp and pc are deprecated in ARM */
michael@0:   str   sp, [r0, #(MCONTEXT_GREGS_OFFSET + 13*4)]
michael@0:   str   lr, [r0, #(MCONTEXT_GREGS_OFFSET + 14*4)]
michael@0: 
michael@0:   /* Save the caller's address in 'pc' */
michael@0:   str   lr, [r0, #(MCONTEXT_GREGS_OFFSET + 15*4)]
michael@0: 
michael@0:   /* Save ucontext_t* pointer accross next call */
michael@0:   mov   r4, r0
michael@0: 
michael@0:   /* Call sigprocmask(SIG_BLOCK, NULL, &(ucontext->uc_sigmask)) */
michael@0:   mov   r0, #0  /* SIG_BLOCK */
michael@0:   mov   r1, #0  /* NULL */
michael@0:   add   r2, r4, #UCONTEXT_SIGMASK_OFFSET
michael@0:   bl    sigprocmask(PLT)
michael@0: 
michael@0:   /* Intentionally do not save the FPU state here. This is because on
michael@0:    * Linux/ARM, one should instead use ptrace(PTRACE_GETFPREGS) or
michael@0:    * ptrace(PTRACE_GETVFPREGS) to get it.
michael@0:    *
michael@0:    * Note that a real implementation of getcontext() would need to save
michael@0:    * this here to allow setcontext()/swapcontext() to work correctly.
michael@0:    */
michael@0: 
michael@0:   /* Restore the values of r4 and lr */
michael@0:   mov   r0, r4
michael@0:   ldr   lr, [r0, #(MCONTEXT_GREGS_OFFSET + 14*4)]
michael@0:   ldr   r4, [r0, #(MCONTEXT_GREGS_OFFSET +  4*4)]
michael@0: 
michael@0:   /* Return 0 */
michael@0:   mov   r0, #0
michael@0:   bx    lr
michael@0: 
michael@0:   .fnend
michael@0:   .size breakpad_getcontext, . - breakpad_getcontext
michael@0: 
michael@0: #elif defined(__i386__)
michael@0: 
michael@0:   .text
michael@0:   .global breakpad_getcontext
michael@0:   .hidden breakpad_getcontext
michael@0:   .align 4
michael@0:   .type breakpad_getcontext, @function
michael@0: 
michael@0: breakpad_getcontext:
michael@0: 
michael@0:   movl 4(%esp), %eax   /* eax = uc */
michael@0: 
michael@0:   /* Save register values */
michael@0:   movl %ecx, MCONTEXT_ECX_OFFSET(%eax)
michael@0:   movl %edx, MCONTEXT_EDX_OFFSET(%eax)
michael@0:   movl %ebx, MCONTEXT_EBX_OFFSET(%eax)
michael@0:   movl %edi, MCONTEXT_EDI_OFFSET(%eax)
michael@0:   movl %esi, MCONTEXT_ESI_OFFSET(%eax)
michael@0:   movl %ebp, MCONTEXT_EBP_OFFSET(%eax)
michael@0: 
michael@0:   movl (%esp), %edx   /* return address */
michael@0:   lea  4(%esp), %ecx  /* exclude return address from stack */
michael@0:   mov  %edx, MCONTEXT_EIP_OFFSET(%eax)
michael@0:   mov  %ecx, MCONTEXT_ESP_OFFSET(%eax)
michael@0: 
michael@0:   xorl %ecx, %ecx
michael@0:   movw %fs, %cx
michael@0:   mov  %ecx, MCONTEXT_FS_OFFSET(%eax)
michael@0: 
michael@0:   movl $0, MCONTEXT_EAX_OFFSET(%eax)
michael@0: 
michael@0:   /* Save floating point state to fpregstate, then update
michael@0:    * the fpregs pointer to point to it */
michael@0:   leal UCONTEXT_FPREGS_MEM_OFFSET(%eax), %ecx
michael@0:   fnstenv (%ecx)
michael@0:   fldenv  (%ecx)
michael@0:   mov %ecx, UCONTEXT_FPREGS_OFFSET(%eax)
michael@0: 
michael@0:   /* Save signal mask: sigprocmask(SIGBLOCK, NULL, &uc->uc_sigmask) */
michael@0:   leal UCONTEXT_SIGMASK_OFFSET(%eax), %edx
michael@0:   xorl %ecx, %ecx
michael@0:   push %edx   /* &uc->uc_sigmask */
michael@0:   push %ecx   /* NULL */
michael@0:   push %ecx   /* SIGBLOCK == 0 on i386 */
michael@0:   call sigprocmask@PLT
michael@0:   addl $12, %esp
michael@0: 
michael@0:   movl $0, %eax
michael@0:   ret
michael@0: 
michael@0:   .size breakpad_getcontext, . - breakpad_getcontext
michael@0: 
michael@0: #else
michael@0: #error "This file has not been ported for your CPU!"
michael@0: #endif