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Add x86_64-linux-gnu emulator
I wanted a tiny scriptable meltdown proof way to run userspace programs and visualize how program execution impacts memory. It helps to explain how things like Actually Portable Executable works. It can show you how the GCC generated code is going about manipulating matrices and more. I didn't feel fully comfortable with Qemu and Bochs because I'm not smart enough to understand them. I wanted something like gVisor but with much stronger levels of assurances. I wanted a single binary that'll run, on all major operating systems with an embedded GPL barrier ZIP filesystem that is tiny enough to transpile to JavaScript and run in browsers too. https://justine.storage.googleapis.com/emulator625.mp4
This commit is contained in:
Justine Tunney
parent
467504308a
commit
f4f4caab0e
1052 changed files with 65667 additions and 7825 deletions
241
tool/build/lib/memory.c
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241
tool/build/lib/memory.c
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/*-*- 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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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/log/check.h"
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#include "libc/macros.h"
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#include "libc/mem/mem.h"
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#include "libc/str/str.h"
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#include "libc/x/x.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/pml4t.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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void SetReadAddr(struct Machine *m, int64_t addr, uint32_t size) {
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m->readaddr = addr;
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m->readsize = size;
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}
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void SetWriteAddr(struct Machine *m, int64_t addr, uint32_t size) {
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m->writeaddr = addr;
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m->writesize = size;
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}
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void *FindReal(struct Machine *m, int64_t v) {
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uint64_t *p;
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unsigned skew;
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unsigned char i;
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skew = v & 0xfff;
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v &= -0x1000;
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for (i = 0; i < ARRAYLEN(m->tlb); ++i) {
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if (m->tlb[i].v == v && m->tlb[i].r) {
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return (char *)m->tlb[i].r + skew;
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}
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}
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for (p = m->cr3, i = 39; i >= 12; i -= 9) {
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if (IsValidPage(p[(v >> i) & 511])) {
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p = UnmaskPageAddr(p[(v >> i) & 511]);
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} else {
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return NULL;
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}
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}
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m->tlbindex = (m->tlbindex + 1) & (ARRAYLEN(m->tlb) - 1);
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m->tlb[m->tlbindex] = m->tlb[0];
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m->tlb[0].r = p;
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m->tlb[0].v = ROUNDDOWN(v, 0x1000);
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DCHECK_NOTNULL(p);
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return (char *)p + skew;
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}
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void *ResolveAddress(struct Machine *m, int64_t v) {
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void *r;
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if ((r = FindReal(m, v))) return r;
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ThrowSegmentationFault(m, v);
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}
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void VirtualSet(struct Machine *m, int64_t v, char c, uint64_t n) {
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char *p;
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uint64_t k;
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k = 0x1000 - (v & 0xfff);
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while (n) {
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k = MIN(k, n);
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p = ResolveAddress(m, v);
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memset(p, c, k);
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n -= k;
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v += k;
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k = 0x1000;
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}
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}
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void VirtualCopy(struct Machine *m, int64_t v, char *r, uint64_t n, bool d) {
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char *p;
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uint64_t k;
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k = 0x1000 - (v & 0xfff);
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while (n) {
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k = MIN(k, n);
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p = ResolveAddress(m, v);
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if (d) {
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memcpy(r, p, k);
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} else {
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memcpy(p, r, k);
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}
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n -= k;
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r += k;
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v += k;
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k = 0x1000;
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}
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}
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void VirtualSend(struct Machine *m, void *dst, int64_t src, uint64_t n) {
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VirtualCopy(m, src, dst, n, true);
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}
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void VirtualRecv(struct Machine *m, int64_t dst, void *src, uint64_t n) {
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VirtualCopy(m, dst, src, n, false);
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}
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void *ReserveAddress(struct Machine *m, int64_t v, size_t n) {
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void *r;
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DCHECK_LE(n, sizeof(m->stash));
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if ((v & 0xfff) + n <= 0x1000) return ResolveAddress(m, v);
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m->stashaddr = v;
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m->stashsize = n;
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r = m->stash;
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VirtualSend(m, r, v, n);
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return r;
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}
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void *AccessRam(struct Machine *m, int64_t v, size_t n, void *p[2],
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uint8_t tmp[n], bool copy) {
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unsigned k;
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uint8_t *a, *b;
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DCHECK_LE(n, 0x1000);
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if ((v & 0xfff) + n <= 0x1000) return ResolveAddress(m, v);
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k = 0x1000;
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k -= v & 0xfff;
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DCHECK_LE(k, 0x1000);
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a = ResolveAddress(m, v);
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b = ResolveAddress(m, v + k);
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if (copy) {
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memcpy(tmp, a, k);
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memcpy(tmp + k, b, n - k);
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}
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p[0] = a;
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p[1] = b;
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return tmp;
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}
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void *Load(struct Machine *m, int64_t v, size_t n, uint8_t b[n]) {
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void *p[2];
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SetReadAddr(m, v, n);
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return AccessRam(m, v, n, p, b, true);
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}
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void *BeginStore(struct Machine *m, int64_t v, size_t n, void *p[2],
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uint8_t b[n]) {
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SetWriteAddr(m, v, n);
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return AccessRam(m, v, n, p, b, false);
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}
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void *BeginStoreNp(struct Machine *m, int64_t v, size_t n, void *p[2],
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uint8_t b[n]) {
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if (!v) return NULL;
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return BeginStore(m, v, n, p, b);
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}
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void *BeginLoadStore(struct Machine *m, int64_t v, size_t n, void *p[2],
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uint8_t b[n]) {
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SetWriteAddr(m, v, n);
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return AccessRam(m, v, n, p, b, true);
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}
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void EndStore(struct Machine *m, int64_t v, size_t n, void *p[2],
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uint8_t b[n]) {
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uint8_t *a;
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unsigned k;
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DCHECK_LE(n, 0x1000);
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if ((v & 0xfff) + n <= 0x1000) return;
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k = 0x1000;
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k -= v & 0xfff;
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DCHECK_GT(k, n);
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DCHECK_NOTNULL(p[0]);
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DCHECK_NOTNULL(p[1]);
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memcpy(p[0], b, k);
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memcpy(p[1], b + k, n - k);
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}
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void EndStoreNp(struct Machine *m, int64_t v, size_t n, void *p[2],
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uint8_t b[n]) {
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if (v) EndStore(m, v, n, p, b);
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}
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void *LoadStr(struct Machine *m, int64_t addr) {
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size_t have;
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char *copy, *page, *p;
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have = 0x1000 - (addr & 0xfff);
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if (!addr) return NULL;
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if (!(page = FindReal(m, addr))) return NULL;
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if ((p = memchr(page, '\0', have))) {
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SetReadAddr(m, addr, p - page);
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return page;
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}
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CHECK_LT(m->freelist.i, ARRAYLEN(m->freelist.p));
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if (!(copy = malloc(have + 0x1000))) return NULL;
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memcpy(copy, page, have);
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for (;;) {
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if (!(page = FindReal(m, addr + have))) break;
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if ((p = memccpy(copy + have, page, '\0', 0x1000))) {
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SetReadAddr(m, addr, have + (p - (copy + have)));
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return (m->freelist.p[m->freelist.i++] = copy);
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}
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have += 0x1000;
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if (!(p = realloc(copy, have + 0x1000))) break;
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copy = p;
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}
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free(copy);
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return NULL;
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}
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void *LoadBuf(struct Machine *m, int64_t addr, size_t size) {
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char *buf, *copy;
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size_t have, need;
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have = 0x1000 - (addr & 0xfff);
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if (!addr) return NULL;
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if (!(buf = FindReal(m, addr))) return NULL;
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if (size > have) {
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CHECK_LT(m->freelist.i, ARRAYLEN(m->freelist.p));
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if (!(copy = malloc(size))) return NULL;
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memcpy(copy, buf, have);
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do {
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need = MIN(0x1000, size - have);
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if ((buf = FindReal(m, addr + have))) {
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memcpy(copy + have, buf, need);
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have += need;
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} else {
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free(copy);
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return NULL;
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}
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} while (have < size);
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}
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SetReadAddr(m, addr, size);
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return buf;
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}
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