mirror of
https://github.com/jart/cosmopolitan.git
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82 lines
3.3 KiB
C
82 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/struct/sigaction.h"
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#include "libc/calls/struct/siginfo.h"
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#include "libc/calls/ucontext.h"
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#include "libc/runtime/runtime.h"
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#include "libc/stdio/stdio.h"
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#include "libc/sysv/consts/auxv.h"
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#include "libc/sysv/consts/sa.h"
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#include "libc/sysv/consts/sig.h"
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#include "third_party/xed/x86.h"
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#define OUTPATH "vdso.elf"
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volatile bool finished;
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void OnSegmentationFault(int sig, siginfo_t *si, void *vctx) {
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struct XedDecodedInst xedd;
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ucontext_t *ctx = vctx;
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xed_decoded_inst_zero_set_mode(&xedd, XED_MACHINE_MODE_LONG_64);
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xed_instruction_length_decode(&xedd, (void *)ctx->uc_mcontext.rip, 15);
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ctx->uc_mcontext.rip += xedd.length;
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finished = true;
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}
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int main(int argc, char *argv[]) {
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FILE *f;
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int byte;
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volatile unsigned char *vdso, *p;
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vdso = (unsigned char *)getauxval(AT_SYSINFO_EHDR);
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if (vdso) {
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fprintf(stderr, "vdso found at address %p\n", vdso);
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} else {
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fprintf(stderr, "error: AT_SYSINFO_EHDR was not in auxiliary values\n");
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return 1;
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}
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f = fopen(OUTPATH, "wb");
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if (!f) {
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fprintf(stderr, "error: fopen(%`'s) failed\n", OUTPATH);
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return 1;
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}
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struct sigaction sa = {
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.sa_sigaction = OnSegmentationFault,
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.sa_flags = SA_SIGINFO,
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};
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sigaction(SIGSEGV, &sa, 0);
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sigaction(SIGBUS, &sa, 0);
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p = vdso;
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for (;;) {
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byte = *p++;
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if (!finished) {
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fputc(byte, f);
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} else {
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break;
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}
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}
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fclose(f);
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fprintf(stderr, "%zu bytes dumped to %s\n", p - vdso, OUTPATH);
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return 0;
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}
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