/*-*- 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/assert.h" #include "libc/bits/likely.h" #include "libc/bits/weaken.h" #include "libc/calls/calls.h" #include "libc/calls/internal.h" #include "libc/calls/strace.internal.h" #include "libc/dce.h" #include "libc/errno.h" #include "libc/intrin/asan.internal.h" #include "libc/intrin/asancodes.h" #include "libc/intrin/describeflags.internal.h" #include "libc/intrin/kprintf.h" #include "libc/intrin/spinlock.h" #include "libc/limits.h" #include "libc/log/backtrace.internal.h" #include "libc/log/libfatal.internal.h" #include "libc/log/log.h" #include "libc/macros.internal.h" #include "libc/nt/process.h" #include "libc/nt/runtime.h" #include "libc/nt/struct/processmemorycounters.h" #include "libc/rand/rand.h" #include "libc/runtime/directmap.internal.h" #include "libc/runtime/internal.h" #include "libc/runtime/memtrack.internal.h" #include "libc/runtime/runtime.h" #include "libc/str/str.h" #include "libc/sysv/consts/map.h" #include "libc/sysv/consts/o.h" #include "libc/sysv/consts/prot.h" #include "libc/sysv/errfuns.h" #define MAP_ANONYMOUS_linux 0x00000020 #define MAP_ANONYMOUS_openbsd 0x00001000 #define MAP_GROWSDOWN_linux 0x00000100 #define MAP_STACK_freebsd 0x00000400 #define MAP_STACK_openbsd 0x00004000 #define IP(X) (intptr_t)(X) #define VIP(X) (void *)IP(X) #define ALIGNED(p) (!(IP(p) & (FRAMESIZE - 1))) #define ADDR(x) ((int64_t)((uint64_t)(x) << 32) >> 16) #define SHADE(x) (((intptr_t)(x) >> 3) + 0x7fff8000) #define FRAME(x) ((int)((intptr_t)(x) >> 16)) static wontreturn void OnUnrecoverableMmapError(const char *s) { if (weaken(__die)) weaken(__die)(); STRACE("%s %m", s); __restorewintty(); _Exit(199); } noasan static bool IsMapped(char *p, size_t n) { return OverlapsImageSpace(p, n) || IsMemtracked(FRAME(p), FRAME(p + (n - 1))); } noasan static bool NeedAutomap(char *p, size_t n) { return !p || OverlapsArenaSpace(p, n) || OverlapsShadowSpace(p, n) || IsMapped(p, n); } noasan static bool ChooseMemoryInterval(int x, int n, int *res) { int i; if (_mmi.i) { i = FindMemoryInterval(&_mmi, x); if (i < _mmi.i) { if (x + n < _mmi.p[i].x) { *res = x; return true; } while (++i < _mmi.i) { if (_mmi.p[i].x - _mmi.p[i - 1].y > n) { *res = _mmi.p[i - 1].y + 1; return true; } } } if (INT_MAX - _mmi.p[i - 1].y >= n) { *res = _mmi.p[i - 1].y + 1; return true; } return false; } else { *res = x; return true; } } noasan static bool Automap(int n, int *res) { *res = -1; if (ChooseMemoryInterval(FRAME(kAutomapStart), n, res)) { assert(*res >= FRAME(kAutomapStart)); if (*res + n <= FRAME(kAutomapStart + (kAutomapStart - 1))) { return true; } else { STRACE("mmap(%.12p, %p) ENOMEM (automap interval exhausted)", ADDR(*res), ADDR(n + 1)); return false; } } else { STRACE("mmap(%.12p, %p) ENOMEM (automap failed)", ADDR(*res), ADDR(n + 1)); return false; } } noasan static size_t GetMemtrackSize(struct MemoryIntervals *mm) { size_t i, n; for (n = i = 0; i < mm->i; ++i) { n += ((size_t)(mm->p[i].y - mm->p[i].x) + 1) << 16; } return n; } static noasan void *FinishMemory(void *addr, size_t size, int prot, int flags, int fd, int64_t off, int f, int x, int n, struct DirectMap dm) { if (!IsWindows() && (flags & MAP_FIXED)) { if (UntrackMemoryIntervals(addr, size)) { OnUnrecoverableMmapError("FIXED UNTRACK FAILED"); } } if (TrackMemoryInterval(&_mmi, x, x + (n - 1), dm.maphandle, prot, flags, false, false, off, size)) { if (sys_munmap(addr, n) == -1) { OnUnrecoverableMmapError("TRACK MUNMAP FAILED"); } return MAP_FAILED; } if (weaken(__asan_map_shadow) && !OverlapsShadowSpace(addr, size)) { weaken(__asan_map_shadow)((intptr_t)addr, size); } return addr; } static noasan void *MapMemory(void *addr, size_t size, int prot, int flags, int fd, int64_t off, int f, int x, int n) { struct DirectMap dm; dm = sys_mmap(addr, size, prot, f, fd, off); if (UNLIKELY(dm.addr == MAP_FAILED)) { if (IsWindows() && (flags & MAP_FIXED)) { OnUnrecoverableMmapError( "can't recover from MAP_FIXED errors on Windows"); } return MAP_FAILED; } if (UNLIKELY(dm.addr != addr)) { OnUnrecoverableMmapError("KERNEL DIDN'T RESPECT MAP_FIXED"); } return FinishMemory(addr, size, prot, flags, fd, off, f, x, n, dm); } /** * Maps memory from system, one frame at a time. * * This is useful on Windows since it allows us to partially unmap or * punch holes into existing mappings. */ static textwindows dontinline noasan void *MapMemories(char *addr, size_t size, int prot, int flags, int fd, int64_t off, int f, int x, int n) { size_t i, m; int64_t oi, sz; struct DirectMap dm; bool iscow, readonlyfile; m = (size_t)(n - 1) << 16; assert(m < size); assert(m + FRAMESIZE >= size); oi = fd == -1 ? 0 : off + m; sz = size - m; dm = sys_mmap(addr + m, sz, prot, f, fd, oi); if (dm.addr == MAP_FAILED) return MAP_FAILED; iscow = (flags & MAP_TYPE) != MAP_SHARED && fd != -1; readonlyfile = (flags & MAP_TYPE) == MAP_SHARED && fd != -1 && (g_fds.p[fd].flags & O_ACCMODE) == O_RDONLY; if (TrackMemoryInterval(&_mmi, x + (n - 1), x + (n - 1), dm.maphandle, prot, flags, readonlyfile, iscow, oi, sz) == -1) { OnUnrecoverableMmapError("MapMemories unrecoverable #1"); } for (i = 0; i < m; i += FRAMESIZE) { oi = fd == -1 ? 0 : off + i; sz = FRAMESIZE; dm = sys_mmap(addr + i, sz, prot, f, fd, oi); if (dm.addr == MAP_FAILED || TrackMemoryInterval(&_mmi, x + i / FRAMESIZE, x + i / FRAMESIZE, dm.maphandle, prot, flags, readonlyfile, iscow, oi, sz) == -1) { OnUnrecoverableMmapError("MapMemories unrecoverable #2"); } } if (weaken(__asan_map_shadow) && !OverlapsShadowSpace(addr, size)) { weaken(__asan_map_shadow)((intptr_t)addr, size); } return addr; } static noasan inline void *Mmap(void *addr, size_t size, int prot, int flags, int fd, int64_t off) { #if defined(SYSDEBUG) && (_KERNTRACE || _NTTRACE) if (IsWindows()) { STRACE("mmap(%p, %'zu, %s, %s, %d, %'ld) → ...", addr, size, DescribeProtFlags(prot), DescribeMapFlags(flags), fd, off); } #endif char *p = addr; bool needguard; struct DirectMap dm; size_t virtualused, virtualneed; int a, b, i, f, m, n, x; if (UNLIKELY(!size)) { STRACE("size=0"); return VIP(einval()); } if (UNLIKELY(!IsLegalSize(size))) { STRACE("size isn't 48-bit"); return VIP(einval()); } if (UNLIKELY(!IsLegalPointer(p))) { STRACE("p isn't 48-bit"); return VIP(einval()); } if (UNLIKELY(!ALIGNED(p))) { STRACE("p isn't 64kb aligned"); return VIP(einval()); } if (UNLIKELY(fd < -1)) { STRACE("mmap(%.12p, %'zu, fd=%d) EBADF", p, size, fd); return VIP(ebadf()); } if (UNLIKELY(!((fd != -1) ^ !!(flags & MAP_ANONYMOUS)))) { STRACE("fd anonymous mismatch"); return VIP(einval()); } if (UNLIKELY(!(!!(flags & MAP_PRIVATE) ^ !!(flags & MAP_SHARED)))) { STRACE("MAP_SHARED ^ MAP_PRIVATE"); return VIP(einval()); } if (UNLIKELY(off < 0)) { STRACE("neg off"); return VIP(einval()); } if (UNLIKELY(INT64_MAX - size < off)) { STRACE("too large"); return VIP(einval()); } if (UNLIKELY(!ALIGNED(off))) { STRACE("p isn't 64kb aligned"); return VIP(einval()); } if ((flags & MAP_FIXED_NOREPLACE) && IsMapped(p, size)) { #ifdef SYSDEBUG if (OverlapsImageSpace(p, size)) { STRACE("overlaps image"); } else { STRACE("overlaps existing"); } #endif return VIP(efault()); } if (__isfdkind(fd, kFdZip)) { STRACE("fd is zipos handle"); return VIP(einval()); } if (__virtualmax < LONG_MAX && (__builtin_add_overflow((virtualused = GetMemtrackSize(&_mmi)), size, &virtualneed) || virtualneed > __virtualmax)) { STRACE("%'zu size + %'zu inuse exceeds virtual memory limit %'zu", size, virtualused, __virtualmax); return VIP(enomem()); } if (fd == -1) { size = ROUNDUP(size, FRAMESIZE); if (IsWindows()) { prot |= PROT_WRITE; /* kludge */ } } n = (int)(size >> 16) + !!(size & (FRAMESIZE - 1)); assert(n > 0); f = (flags & ~MAP_FIXED_NOREPLACE) | MAP_FIXED; if (flags & MAP_FIXED) { x = FRAME(p); if (IsWindows()) { if (UntrackMemoryIntervals(p, size)) { OnUnrecoverableMmapError("FIXED UNTRACK FAILED"); } } } else if (!NeedAutomap(p, size)) { x = FRAME(p); } else if (!Automap(n, &x)) { STRACE("AUTOMAP OUT OF MEMORY D:"); return VIP(enomem()); } needguard = false; p = (char *)ADDR(x); if ((f & MAP_TYPE) == MAP_STACK) { if (~f & MAP_ANONYMOUS) { STRACE("MAP_STACK must be anonymous"); return VIP(einval()); } f &= ~MAP_TYPE; f |= MAP_PRIVATE; if (IsOpenbsd()) { // openbsd:dubstack // on openbsd this is less about scalability of threads, and more // about defining the legal intervals for the RSP register. sadly // openbsd doesn't let us create a new fixed stack mapping. but.. // openbsd does allow us to overwrite existing fixed mappings, to // authorize its usage as a stack. if (sys_mmap(p, size, prot, f, fd, off).addr == MAP_FAILED) { return MAP_FAILED; } f |= MAP_STACK_openbsd; needguard = true; } else if (IsLinux()) { // by default MAP_GROWSDOWN will auto-allocate 10mb of pages. it's // supposed to stop growing if an adjacent allocation exists, to // prevent your stacks from overlapping on each other. we're not // able to easily assume a mapping beneath this one exists. even // if we could, the linux kernel requires for muh security reasons // that stacks be at least 1mb away from each other, so it's not // possible to avoid this call if our goal is to have 60kb stacks // with 4kb guards like a sane multithreaded production system. // however this 1mb behavior oddly enough is smart enough to not // apply if the mapping is a manually-created guard page. if ((dm = sys_mmap(p + size - PAGESIZE, PAGESIZE, prot, f | MAP_GROWSDOWN_linux, fd, off)) .addr == MAP_FAILED) { return MAP_FAILED; } sys_mmap(p, PAGESIZE, PROT_NONE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); dm.addr = p; return FinishMemory(p, size, prot, flags, fd, off, f, x, n, dm); } else { if (IsFreebsd()) { f |= MAP_STACK_freebsd; } needguard = true; } } if (!IsWindows()) { p = MapMemory(p, size, prot, flags, fd, off, f, x, n); } else { p = MapMemories(p, size, prot, flags, fd, off, f, x, n); } if (p != MAP_FAILED) { if (needguard) { if (IsWindows()) _spunlock(&_mmi.lock); mprotect(p, PAGESIZE, PROT_NONE); if (IsAsan()) { __repstosb((void *)(((intptr_t)p >> 3) + 0x7fff8000), kAsanStackOverflow, PAGESIZE / 8); } if (IsWindows()) _spinlock(&_mmi.lock); } } return p; } /** * Beseeches system for page-table entries, e.g. * * char *m; * m = mmap(NULL, FRAMESIZE, PROT_READ | PROT_WRITE, * MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); * munmap(m, FRAMESIZE); * * @param addr should be 0 to let your memory manager choose address; * unless MAP_FIXED or MAP_FIXED_NOREPLACE are specified in flags * in which case this function will do precicely as you ask, even * if p=0 (in which you need -fno-delete-null-pointer-checks); it * needs to be 64kb aligned because it's a wise choice that sadly * needs to be made mandatory because of Windows although you can * use __sys_mmap() to circumvent it on System Five in which case * runtime support services, e.g. asan memory safety, could break * @param size must be >0 and needn't be a multiple of FRAMESIZE, but * will be rounded up to FRAMESIZE automatically if MAP_ANONYMOUS * is specified * @param prot can have PROT_READ/PROT_WRITE/PROT_EXEC/PROT_NONE/etc. * @param flags should have one of the following masked by `MAP_TYPE` * - `MAP_FILE` in which case `fd != -1` should be the case * - `MAP_PRIVATE` for copy-on-write behavior of writeable pages * - `MAP_SHARED` to create shared memory between processes * - `MAP_STACK` to create a grows-down alloc, where a guard page * is automatically protected at the bottom: FreeBSD's behavior * is polyfilled across platforms; uses MAP_GROWSDOWN on Linux * too for extra oomph (do not use MAP_GROWSDOWN!) and this is * completely mandatory on OpenBSD but helps perf elsewhere if * you need to create 10,000 threads. This flag is the reason * why `STACK_FRAME_UNLIMITED` toil is important, because this * only allocates a 4096-byte guard page, thus we need the GCC * compile-time checks to ensure some char[8192] vars will not * create an undetectable overflow into another thread's stack * Your `flags` may optionally bitwise or any of the following: * - `MAP_FIXED` in which case `addr` becomes more than a hint * - `MAP_FIXED_NOREPLACE` to protect existing maps (Linux-only) * - `MAP_ANONYMOUS` in which case `fd == -1` should be the case * - `MAP_CONCEAL` is FreeBSD/NetBSD/OpenBSD-only * - `MAP_NORESERVE` is Linux/XNU/NetBSD-only * - `MAP_LOCKED` is Linux-only * - `MAP_POPULATE` is Linux-only * - `MAP_NONBLOCK` is Linux-only * @param fd is an open()'d file descriptor, whose contents shall be * made available w/ automatic reading at the chosen address and * must be -1 if MAP_ANONYMOUS is specified * @param off specifies absolute byte index of fd's file for mapping, * should be zero if MAP_ANONYMOUS is specified, and sadly needs * to be 64kb aligned too * @return virtual base address of new mapping, or MAP_FAILED w/ errno */ noasan void *mmap(void *addr, size_t size, int prot, int flags, int fd, int64_t off) { void *res; _spinlock(&_mmi.lock); res = Mmap(addr, size, prot, flags, fd, off); _spunlock(&_mmi.lock); STRACE("mmap(%p, %'zu, %s, %s, %d, %'ld) → %p% m", addr, size, DescribeProtFlags(prot), DescribeMapFlags(flags), fd, off, res); return res; }