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https://github.com/jart/cosmopolitan.git
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1422e96b4e
There's a new program named ape/ape-m1.c which will be used to build an embeddable binary that can load ape and elf executables. The support is mostly working so far, but still chasing down ABI issues.
121 lines
5.6 KiB
C
121 lines
5.6 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 "ape/sections.internal.h"
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#include "libc/dce.h"
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#include "libc/intrin/bits.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/runtime/internal.h"
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#include "libc/runtime/morph.h"
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#include "libc/thread/tls.h"
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typedef char xmm_t __attribute__((__vector_size__(16), __aligned__(1)));
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privileged void __morph_tls(void) {
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#ifdef __x86_64__
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// We need to rewrite SysV _Thread_local code. You MUST use the
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// -mno-tls-direct-seg-refs flag which generates code like this
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//
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// 64 48 8b 0R4 25 00 00 00 00 mov %fs:0,%R
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// 64 48 03 0R4 25 00 00 00 00 add %fs:0,%R
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//
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// Which on Mac we can replace with this:
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//
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// 65 48 8b 0R4 25 30 00 00 00 mov %gs:0x30,%R
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//
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// Since we have no idea where the TLS instructions exist in the
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// binary, we need to disassemble the whole program image. This'll
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// potentially take a few milliseconds for some larger programs.
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//
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// We check `_tls_content` which is generated by the linker script
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// since it lets us determine ahead of time if _Thread_local vars
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// have actually been linked into this program.
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if (IsWindows() || IsXnu()) {
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int n;
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uint64_t w;
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sigset_t mask;
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unsigned m, dis;
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unsigned char *p;
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__morph_begin(&mask);
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if (IsXnu()) {
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// Apple is quite straightforward to patch. We basically
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// just change the segment register, and the linear slot
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// address 0x30 was promised to us, according to Go team
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// https://github.com/golang/go/issues/23617
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dis = 0x30;
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} else {
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// MSVC __declspec(thread) generates binary code for this
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// %gs:0x1480 abi. So long as TlsAlloc() isn't called >64
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// times we should be good.
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dis = 0x1480 + __tls_index * 8;
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}
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// iterate over modifiable code looking for 9 byte instruction
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// this would take 30 ms using xed to enable tls on python.com
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for (p = _ereal; p + 9 <= __privileged_start; p += n) {
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// use sse to zoom zoom to fs register prefixes
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// that way it'll take 1 ms to morph python.com
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while (p + 9 + 16 <= __privileged_start) {
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if ((m = __builtin_ia32_pmovmskb128(
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*(xmm_t *)p == (xmm_t){0144, 0144, 0144, 0144, 0144, 0144,
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0144, 0144, 0144, 0144, 0144, 0144,
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0144, 0144, 0144, 0144}))) {
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m = __builtin_ctzll(m);
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p += m;
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break;
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} else {
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p += 16;
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}
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}
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// we're checking for the following expression:
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// 0144 == p[0] && // %fs
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// 0110 == (p[1] & 0373) && // rex.w (and ignore rex.r)
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// (0213 == p[2] || // mov reg/mem → reg (word-sized)
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// 0003 == p[2]) && // add reg/mem → reg (word-sized)
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// 0004 == (p[3] & 0307) && // mod/rm (4,reg,0) means sib → reg
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// 0045 == p[4] && // sib (5,4,0) → (rbp,rsp,0) → disp32
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// 0000 == p[5] && // displacement (von Neumann endian)
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// 0000 == p[6] && // displacement
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// 0000 == p[7] && // displacement
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// 0000 == p[8] // displacement
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w = READ64LE(p) & READ64LE("\377\373\377\307\377\377\377\377");
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if ((w == READ64LE("\144\110\213\004\045\000\000\000") ||
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w == READ64LE("\144\110\003\004\045\000\000\000")) &&
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!p[8]) {
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// now change the code
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p[0] = 0145; // change %fs to %gs
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p[5] = (dis & 0x000000ff) >> 000; // displacement
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p[6] = (dis & 0x0000ff00) >> 010; // displacement
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p[7] = (dis & 0x00ff0000) >> 020; // displacement
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p[8] = (dis & 0xff000000) >> 030; // displacement
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// advance to the next instruction
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n = 9;
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} else {
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n = 1;
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}
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}
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__morph_end(&mask);
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}
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#endif
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}
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