1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <private/bionic_asm.h> 30 31 // gdb is smart enough to unwind through signal frames with just the regular 32 // CFI information but libgcc and libunwind both need extra help. We do this 33 // by using .fnstart/.fnend and inserting a nop before both __restore and 34 // __restore_rt (but covered by the .fnstart/.fnend) so that although they're 35 // not inside the functions from objdump's point of view, an unwinder that 36 // blindly looks at the previous instruction (but is then smart enough to check 37 // the unwind information to find out where it landed) gets the right answer. 38 // Make sure not to have both DWARF and ARM unwind information, so only 39 // use the ARM unwind information. 40 41 // We need to place .fnstart ourselves (but we may as well keep the free .fnend). 42 #undef __bionic_asm_custom_entry 43 #define __bionic_asm_custom_entry(f) 44 45 .fnstart 46 .save {r0-r15} 47 .pad #32 48 nop 49 ENTRY_PRIVATE_NO_DWARF(__restore) 50 // This function must have exactly this instruction sequence. 51 mov r7, #__NR_sigreturn 52 swi #0 53 END_NO_DWARF(__restore) 54 55 .fnstart 56 .save {r0-r15} 57 .pad #160 58 nop 59 ENTRY_PRIVATE_NO_DWARF(__restore_rt) 60 // This function must have exactly this instruction sequence. 61 mov r7, #__NR_rt_sigreturn 62 swi #0 63 END_NO_DWARF(__restore_rt) 64
