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59 lines
3.3 KiB
C
59 lines
3.3 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/calls.h"
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#include "libc/macros.internal.h"
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#include "libc/runtime/runtime.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/prot.h"
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#include "third_party/xed/x86.h"
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/**
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* Returns lengths of x86 ops in binary.
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*
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* The first decoded instruction is at `_ereal`. Lengths can be 1 to 15
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* bytes. Each byte in the return value is in that range, and the array
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* is NUL terminated. The returned memory is memoized, since this costs
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* some time. For example, for a 10mb Python binary, it takes 20 millis
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* so the basic idea is is you can use this output multiple times which
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* is a faster way to iterate over the binary than calling Xed.
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*
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* @return nul-terminated length array on success, or null
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*/
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privileged unsigned char *GetInstructionLengths(void) {
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static bool once;
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int i, n, err, len, rem;
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static unsigned char *res;
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struct XedDecodedInst xedd;
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unsigned char *p, *mem, *code;
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if (!once) {
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if ((mem = mmap(0, ROUNDUP(__privileged_addr - _ereal + 1, FRAMESIZE),
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PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1,
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0)) != MAP_FAILED) {
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for (p = mem, code = _ereal; code < __privileged_addr; code += len) {
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rem = __privileged_addr - code;
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xed_decoded_inst_zero_set_mode(&xedd, XED_MACHINE_MODE_LONG_64);
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err = xed_instruction_length_decode(&xedd, code, rem);
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*p++ = len = !err ? xedd.length : 1;
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}
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res = mem;
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}
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once = true;
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}
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return res;
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}
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