/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│ │vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│ ╞══════════════════════════════════════════════════════════════════════════════╡ │ Copyright 2020 Justine Alexandra Roberts Tunney │ │ │ │ Permission to use, copy, modify, and/or distribute this software for │ │ any purpose with or without fee is hereby granted, provided that the │ │ above copyright notice and this permission notice appear in all copies. │ │ │ │ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │ │ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │ │ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │ │ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │ │ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │ │ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │ │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │ │ PERFORMANCE OF THIS SOFTWARE. │ ╚─────────────────────────────────────────────────────────────────────────────*/ #include "libc/macros.h" #include "libc/nexgen32e/bsf.h" #include "libc/str/str.h" #include "third_party/xed/x86.h" #include "tool/build/lib/address.h" #include "tool/build/lib/endian.h" #include "tool/build/lib/machine.h" #include "tool/build/lib/memory.h" #include "tool/build/lib/stats.h" #include "tool/build/lib/throw.h" static bool IsOpcodeEqual(struct XedDecodedInst *xedd, uint8_t *a) { uint64_t w; if (xedd->length) { if (xedd->length <= 7) { w = Read64(a) ^ Read64(xedd->bytes); return !w || bsfl(w) >= (xedd->length << 3); } else { return memcmp(a, xedd->bytes, xedd->length) == 0; } } else { return false; } } static void DecodeInstruction(struct Machine *m, uint8_t *p, unsigned n) { struct XedDecodedInst xedd[1]; xed_decoded_inst_zero_set_mode(xedd, m->mode); if (!xed_instruction_length_decode(xedd, p, n)) { memcpy(m->xedd, xedd, sizeof(m->icache[0])); } else { HaltMachine(m, kMachineDecodeError); } } static noinline void LoadInstructionSlow(struct Machine *m, uint64_t ip) { unsigned i; uint8_t *addr; uint8_t copy[15], *toil; i = 0x1000 - (ip & 0xfff); addr = ResolveAddress(m, ip); if ((toil = FindReal(m, ip + i))) { memcpy(copy, addr, i); memcpy(copy + i, toil, 15 - i); DecodeInstruction(m, copy, 15); } else { DecodeInstruction(m, addr, i); } } void LoadInstruction(struct Machine *m) { uint64_t ip; unsigned key; uint8_t *addr; ip = Read64(m->cs) + MaskAddress(m->mode & 3, m->ip); key = ip & (ARRAYLEN(m->icache) - 1); m->xedd = (struct XedDecodedInst *)m->icache[key]; if ((ip & 0xfff) < 0x1000 - 15) { if (ip - (ip & 0xfff) == m->codevirt && m->codehost) { addr = m->codehost + (ip & 0xfff); } else { m->codevirt = ip - (ip & 0xfff); m->codehost = ResolveAddress(m, m->codevirt); addr = m->codehost + (ip & 0xfff); } if (!IsOpcodeEqual(m->xedd, addr)) { DecodeInstruction(m, addr, 15); } } else { LoadInstructionSlow(m, ip); } }