52 lines
2.7 KiB
ArmAsm
52 lines
2.7 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/macros.h"
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#include "libc/notice.inc"
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#include "libc/sysv/consts/auxv.h"
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.source __FILE__
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/ Canary for -fstack-protector.
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/
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/ This global is referenced by synthetic code generated by GCC.
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/ The -mstack-protector-guard=global flag might need to be passed.
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/
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/ @note this value is protected by piro
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.initbss 301,_init___stack_chk_guard
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__stack_chk_guard:
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.quad 0
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.endobj __stack_chk_guard,globl
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.previous
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.init.start 301,_init___stack_chk_guard
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mov kStartTsc(%rip),%rax
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mov AT_RANDOM,%edx # modern linux provides this
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test %edx,%edx
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jz 1f
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pushpop -16,%rcx
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0: add $16,%rcx # ax ^= di[1][0] if di[0]=AT_RANDOM
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cmpq $0,(%r15,%rcx) # %r15 is qword(*auxv)[2]
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jz 1f # @see libc/crt/crt.S
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cmp %rdx,(%r15,%rcx)
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jne 0b
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mov 8(%r15,%rcx),%rcx
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xor (%rcx),%rax
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1: stosq
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.init.end 301,_init___stack_chk_guard
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