91 lines
3.8 KiB
C
91 lines
3.8 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 2020 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/macros.h"
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#include "libc/nexgen32e/bsf.h"
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#include "libc/str/str.h"
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#include "third_party/xed/x86.h"
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#include "tool/build/lib/address.h"
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#include "tool/build/lib/endian.h"
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#include "tool/build/lib/machine.h"
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#include "tool/build/lib/memory.h"
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#include "tool/build/lib/stats.h"
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#include "tool/build/lib/throw.h"
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static bool IsOpcodeEqual(struct XedDecodedInst *xedd, uint8_t *a) {
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uint64_t w;
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if (xedd->length) {
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if (xedd->length <= 7) {
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w = Read64(a) ^ Read64(xedd->bytes);
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return !w || bsfl(w) >= (xedd->length << 3);
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} else {
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return memcmp(a, xedd->bytes, xedd->length) == 0;
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}
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} else {
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return false;
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}
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}
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static void DecodeInstruction(struct Machine *m, uint8_t *p, unsigned n) {
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struct XedDecodedInst xedd[1];
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xed_decoded_inst_zero_set_mode(xedd, m->mode);
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if (!xed_instruction_length_decode(xedd, p, n)) {
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memcpy(m->xedd, xedd, sizeof(m->icache[0]));
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} else {
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HaltMachine(m, kMachineDecodeError);
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}
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}
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static noinline void LoadInstructionSlow(struct Machine *m, uint64_t ip) {
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unsigned i;
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uint8_t *addr;
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uint8_t copy[15], *toil;
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i = 0x1000 - (ip & 0xfff);
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addr = ResolveAddress(m, ip);
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if ((toil = FindReal(m, ip + i))) {
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memcpy(copy, addr, i);
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memcpy(copy + i, toil, 15 - i);
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DecodeInstruction(m, copy, 15);
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} else {
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DecodeInstruction(m, addr, i);
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}
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}
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void LoadInstruction(struct Machine *m) {
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uint64_t ip;
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unsigned key;
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uint8_t *addr;
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ip = Read64(m->cs) + MaskAddress(m->mode & 3, m->ip);
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key = ip & (ARRAYLEN(m->icache) - 1);
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m->xedd = (struct XedDecodedInst *)m->icache[key];
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if ((ip & 0xfff) < 0x1000 - 15) {
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if (ip - (ip & 0xfff) == m->codevirt && m->codehost) {
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addr = m->codehost + (ip & 0xfff);
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} else {
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m->codevirt = ip - (ip & 0xfff);
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m->codehost = ResolveAddress(m, m->codevirt);
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addr = m->codehost + (ip & 0xfff);
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}
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if (!IsOpcodeEqual(m->xedd, addr)) {
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DecodeInstruction(m, addr, 15);
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}
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} else {
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LoadInstructionSlow(m, ip);
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}
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}
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