/* * mmap support for qemu * * Copyright (c) 2003 Fabrice Bellard * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see <http://www.gnu.org/licenses/>. */ #include <stdlib.h> #include <stdio.h> #include <stdarg.h> #include <string.h> #include <unistd.h> #include <errno.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/mman.h> #include <linux/mman.h> #include <linux/unistd.h> #include "qemu.h" #include "qemu-common.h" //#define DEBUG_MMAP #if defined(CONFIG_USE_NPTL) static pthread_mutex_t mmap_mutex = PTHREAD_MUTEX_INITIALIZER; static __thread int mmap_lock_count; void mmap_lock(void) { if (mmap_lock_count++ == 0) { pthread_mutex_lock(&mmap_mutex); } } void mmap_unlock(void) { if (--mmap_lock_count == 0) { pthread_mutex_unlock(&mmap_mutex); } } /* Grab lock to make sure things are in a consistent state after fork(). */ void mmap_fork_start(void) { if (mmap_lock_count) abort(); pthread_mutex_lock(&mmap_mutex); } void mmap_fork_end(int child) { if (child) pthread_mutex_init(&mmap_mutex, NULL); else pthread_mutex_unlock(&mmap_mutex); } #else /* We aren't threadsafe to start with, so no need to worry about locking. */ void mmap_lock(void) { } void mmap_unlock(void) { } #endif /* NOTE: all the constants are the HOST ones, but addresses are target. */ int target_mprotect(abi_ulong start, abi_ulong len, int prot) { abi_ulong end, host_start, host_end, addr; int prot1, ret; #ifdef DEBUG_MMAP printf("mprotect: start=0x" TARGET_ABI_FMT_lx "len=0x" TARGET_ABI_FMT_lx " prot=%c%c%c\n", start, len, prot & PROT_READ ? 'r' : '-', prot & PROT_WRITE ? 'w' : '-', prot & PROT_EXEC ? 'x' : '-'); #endif if ((start & ~TARGET_PAGE_MASK) != 0) return -EINVAL; len = TARGET_PAGE_ALIGN(len); end = start + len; if (end < start) return -EINVAL; prot &= PROT_READ | PROT_WRITE | PROT_EXEC; if (len == 0) return 0; mmap_lock(); host_start = start & qemu_host_page_mask; host_end = HOST_PAGE_ALIGN(end); if (start > host_start) { /* handle host page containing start */ prot1 = prot; for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) { prot1 |= page_get_flags(addr); } if (host_end == host_start + qemu_host_page_size) { for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { prot1 |= page_get_flags(addr); } end = host_end; } ret = mprotect(g2h(host_start), qemu_host_page_size, prot1 & PAGE_BITS); if (ret != 0) goto error; host_start += qemu_host_page_size; } if (end < host_end) { prot1 = prot; for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { prot1 |= page_get_flags(addr); } ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size, prot1 & PAGE_BITS); if (ret != 0) goto error; host_end -= qemu_host_page_size; } /* handle the pages in the middle */ if (host_start < host_end) { ret = mprotect(g2h(host_start), host_end - host_start, prot); if (ret != 0) goto error; } page_set_flags(start, start + len, prot | PAGE_VALID); mmap_unlock(); return 0; error: mmap_unlock(); return ret; } /* map an incomplete host page */ static int mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong end, int prot, int flags, int fd, abi_ulong offset) { abi_ulong real_end, addr; void *host_start; int prot1, prot_new; real_end = real_start + qemu_host_page_size; host_start = g2h(real_start); /* get the protection of the target pages outside the mapping */ prot1 = 0; for(addr = real_start; addr < real_end; addr++) { if (addr < start || addr >= end) prot1 |= page_get_flags(addr); } if (prot1 == 0) { /* no page was there, so we allocate one */ void *p = mmap(host_start, qemu_host_page_size, prot, flags | MAP_ANONYMOUS, -1, 0); if (p == MAP_FAILED) return -1; prot1 = prot; } prot1 &= PAGE_BITS; prot_new = prot | prot1; if (!(flags & MAP_ANONYMOUS)) { /* msync() won't work here, so we return an error if write is possible while it is a shared mapping */ if ((flags & MAP_TYPE) == MAP_SHARED && (prot & PROT_WRITE)) return -1; /* adjust protection to be able to read */ if (!(prot1 & PROT_WRITE)) mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE); /* read the corresponding file data */ if (pread(fd, g2h(start), end - start, offset) == -1) return -1; /* put final protection */ if (prot_new != (prot1 | PROT_WRITE)) mprotect(host_start, qemu_host_page_size, prot_new); } else { /* just update the protection */ if (prot_new != prot1) { mprotect(host_start, qemu_host_page_size, prot_new); } } return 0; } #if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64 # define TASK_UNMAPPED_BASE (1ul << 38) #elif defined(__CYGWIN__) /* Cygwin doesn't have a whole lot of address space. */ # define TASK_UNMAPPED_BASE 0x18000000 #else # define TASK_UNMAPPED_BASE 0x40000000 #endif abi_ulong mmap_next_start = TASK_UNMAPPED_BASE; unsigned long last_brk; #ifdef CONFIG_USE_GUEST_BASE /* Subroutine of mmap_find_vma, used when we have pre-allocated a chunk of guest address space. */ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size) { abi_ulong addr; abi_ulong end_addr; int prot; int looped = 0; if (size > RESERVED_VA) { return (abi_ulong)-1; } size = HOST_PAGE_ALIGN(size); end_addr = start + size; if (end_addr > RESERVED_VA) { end_addr = RESERVED_VA; } addr = end_addr - qemu_host_page_size; while (1) { if (addr > end_addr) { if (looped) { return (abi_ulong)-1; } end_addr = RESERVED_VA; addr = end_addr - qemu_host_page_size; looped = 1; continue; } prot = page_get_flags(addr); if (prot) { end_addr = addr; } if (addr + size == end_addr) { break; } addr -= qemu_host_page_size; } if (start == mmap_next_start) { mmap_next_start = addr; } return addr; } #endif /* * Find and reserve a free memory area of size 'size'. The search * starts at 'start'. * It must be called with mmap_lock() held. * Return -1 if error. */ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) { void *ptr, *prev; abi_ulong addr; int wrapped, repeat; /* If 'start' == 0, then a default start address is used. */ if (start == 0) { start = mmap_next_start; } else { start &= qemu_host_page_mask; } size = HOST_PAGE_ALIGN(size); #ifdef CONFIG_USE_GUEST_BASE if (RESERVED_VA) { return mmap_find_vma_reserved(start, size); } #endif addr = start; wrapped = repeat = 0; prev = 0; for (;; prev = ptr) { /* * Reserve needed memory area to avoid a race. * It should be discarded using: * - mmap() with MAP_FIXED flag * - mremap() with MREMAP_FIXED flag * - shmat() with SHM_REMAP flag */ ptr = mmap(g2h(addr), size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, -1, 0); /* ENOMEM, if host address space has no memory */ if (ptr == MAP_FAILED) { return (abi_ulong)-1; } /* Count the number of sequential returns of the same address. This is used to modify the search algorithm below. */ repeat = (ptr == prev ? repeat + 1 : 0); if (h2g_valid(ptr + size - 1)) { addr = h2g(ptr); if ((addr & ~TARGET_PAGE_MASK) == 0) { /* Success. */ if (start == mmap_next_start && addr >= TASK_UNMAPPED_BASE) { mmap_next_start = addr + size; } return addr; } /* The address is not properly aligned for the target. */ switch (repeat) { case 0: /* Assume the result that the kernel gave us is the first with enough free space, so start again at the next higher target page. */ addr = TARGET_PAGE_ALIGN(addr); break; case 1: /* Sometimes the kernel decides to perform the allocation at the top end of memory instead. */ addr &= TARGET_PAGE_MASK; break; case 2: /* Start over at low memory. */ addr = 0; break; default: /* Fail. This unaligned block must the last. */ addr = -1; break; } } else { /* Since the result the kernel gave didn't fit, start again at low memory. If any repetition, fail. */ addr = (repeat ? -1 : 0); } /* Unmap and try again. */ munmap(ptr, size); /* ENOMEM if we checked the whole of the target address space. */ if (addr == (abi_ulong)-1) { return (abi_ulong)-1; } else if (addr == 0) { if (wrapped) { return (abi_ulong)-1; } wrapped = 1; /* Don't actually use 0 when wrapping, instead indicate that we'd truly like an allocation in low memory. */ addr = (mmap_min_addr > TARGET_PAGE_SIZE ? TARGET_PAGE_ALIGN(mmap_min_addr) : TARGET_PAGE_SIZE); } else if (wrapped && addr >= start) { return (abi_ulong)-1; } } } /* NOTE: all the constants are the HOST ones */ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, int flags, int fd, abi_ulong offset) { abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len; unsigned long host_start; mmap_lock(); #ifdef DEBUG_MMAP { printf("mmap: start=0x" TARGET_ABI_FMT_lx " len=0x" TARGET_ABI_FMT_lx " prot=%c%c%c flags=", start, len, prot & PROT_READ ? 'r' : '-', prot & PROT_WRITE ? 'w' : '-', prot & PROT_EXEC ? 'x' : '-'); if (flags & MAP_FIXED) printf("MAP_FIXED "); if (flags & MAP_ANONYMOUS) printf("MAP_ANON "); switch(flags & MAP_TYPE) { case MAP_PRIVATE: printf("MAP_PRIVATE "); break; case MAP_SHARED: printf("MAP_SHARED "); break; default: printf("[MAP_TYPE=0x%x] ", flags & MAP_TYPE); break; } printf("fd=%d offset=" TARGET_ABI_FMT_lx "\n", fd, offset); } #endif if (offset & ~TARGET_PAGE_MASK) { errno = EINVAL; goto fail; } len = TARGET_PAGE_ALIGN(len); if (len == 0) goto the_end; real_start = start & qemu_host_page_mask; /* When mapping files into a memory area larger than the file, accesses to pages beyond the file size will cause a SIGBUS. For example, if mmaping a file of 100 bytes on a host with 4K pages emulating a target with 8K pages, the target expects to be able to access the first 8K. But the host will trap us on any access beyond 4K. When emulating a target with a larger page-size than the hosts, we may need to truncate file maps at EOF and add extra anonymous pages up to the targets page boundary. */ if ((qemu_real_host_page_size < TARGET_PAGE_SIZE) && !(flags & MAP_ANONYMOUS)) { struct stat sb; if (fstat (fd, &sb) == -1) goto fail; /* Are we trying to create a map beyond EOF?. */ if (offset + len > sb.st_size) { /* If so, truncate the file map at eof aligned with the hosts real pagesize. Additional anonymous maps will be created beyond EOF. */ len = (sb.st_size - offset); len += qemu_real_host_page_size - 1; len &= ~(qemu_real_host_page_size - 1); } } if (!(flags & MAP_FIXED)) { abi_ulong mmap_start; void *p; host_offset = offset & qemu_host_page_mask; host_len = len + offset - host_offset; host_len = HOST_PAGE_ALIGN(host_len); mmap_start = mmap_find_vma(real_start, host_len); if (mmap_start == (abi_ulong)-1) { errno = ENOMEM; goto fail; } /* Note: we prefer to control the mapping address. It is especially important if qemu_host_page_size > qemu_real_host_page_size */ p = mmap(g2h(mmap_start), host_len, prot, flags | MAP_FIXED | MAP_ANONYMOUS, -1, 0); if (p == MAP_FAILED) goto fail; /* update start so that it points to the file position at 'offset' */ host_start = (unsigned long)p; if (!(flags & MAP_ANONYMOUS)) { p = mmap(g2h(mmap_start), len, prot, flags | MAP_FIXED, fd, host_offset); host_start += offset - host_offset; } start = h2g(host_start); } else { if (start & ~TARGET_PAGE_MASK) { errno = EINVAL; goto fail; } end = start + len; real_end = HOST_PAGE_ALIGN(end); /* * Test if requested memory area fits target address space * It can fail only on 64-bit host with 32-bit target. * On any other target/host host mmap() handles this error correctly. */ if ((unsigned long)start + len - 1 > (abi_ulong) -1) { errno = EINVAL; goto fail; } /* worst case: we cannot map the file because the offset is not aligned, so we read it */ if (!(flags & MAP_ANONYMOUS) && (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) { /* msync() won't work here, so we return an error if write is possible while it is a shared mapping */ if ((flags & MAP_TYPE) == MAP_SHARED && (prot & PROT_WRITE)) { errno = EINVAL; goto fail; } retaddr = target_mmap(start, len, prot | PROT_WRITE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (retaddr == -1) goto fail; if (pread(fd, g2h(start), len, offset) == -1) goto fail; if (!(prot & PROT_WRITE)) { ret = target_mprotect(start, len, prot); if (ret != 0) { start = ret; goto the_end; } } goto the_end; } /* handle the start of the mapping */ if (start > real_start) { if (real_end == real_start + qemu_host_page_size) { /* one single host page */ ret = mmap_frag(real_start, start, end, prot, flags, fd, offset); if (ret == -1) goto fail; goto the_end1; } ret = mmap_frag(real_start, start, real_start + qemu_host_page_size, prot, flags, fd, offset); if (ret == -1) goto fail; real_start += qemu_host_page_size; } /* handle the end of the mapping */ if (end < real_end) { ret = mmap_frag(real_end - qemu_host_page_size, real_end - qemu_host_page_size, real_end, prot, flags, fd, offset + real_end - qemu_host_page_size - start); if (ret == -1) goto fail; real_end -= qemu_host_page_size; } /* map the middle (easier) */ if (real_start < real_end) { void *p; unsigned long offset1; if (flags & MAP_ANONYMOUS) offset1 = 0; else offset1 = offset + real_start - start; p = mmap(g2h(real_start), real_end - real_start, prot, flags, fd, offset1); if (p == MAP_FAILED) goto fail; } } the_end1: page_set_flags(start, start + len, prot | PAGE_VALID); the_end: #ifdef DEBUG_MMAP printf("ret=0x" TARGET_ABI_FMT_lx "\n", start); page_dump(stdout); printf("\n"); #endif mmap_unlock(); return start; fail: mmap_unlock(); return -1; } static void mmap_reserve(abi_ulong start, abi_ulong size) { abi_ulong real_start; abi_ulong real_end; abi_ulong addr; abi_ulong end; int prot; real_start = start & qemu_host_page_mask; real_end = HOST_PAGE_ALIGN(start + size); end = start + size; if (start > real_start) { /* handle host page containing start */ prot = 0; for (addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { prot |= page_get_flags(addr); } if (real_end == real_start + qemu_host_page_size) { for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { prot |= page_get_flags(addr); } end = real_end; } if (prot != 0) real_start += qemu_host_page_size; } if (end < real_end) { prot = 0; for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { prot |= page_get_flags(addr); } if (prot != 0) real_end -= qemu_host_page_size; } if (real_start != real_end) { mmap(g2h(real_start), real_end - real_start, PROT_NONE, MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE, -1, 0); } } int target_munmap(abi_ulong start, abi_ulong len) { abi_ulong end, real_start, real_end, addr; int prot, ret; #ifdef DEBUG_MMAP printf("munmap: start=0x" TARGET_ABI_FMT_lx " len=0x" TARGET_ABI_FMT_lx "\n", start, len); #endif if (start & ~TARGET_PAGE_MASK) return -EINVAL; len = TARGET_PAGE_ALIGN(len); if (len == 0) return -EINVAL; mmap_lock(); end = start + len; real_start = start & qemu_host_page_mask; real_end = HOST_PAGE_ALIGN(end); if (start > real_start) { /* handle host page containing start */ prot = 0; for(addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { prot |= page_get_flags(addr); } if (real_end == real_start + qemu_host_page_size) { for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { prot |= page_get_flags(addr); } end = real_end; } if (prot != 0) real_start += qemu_host_page_size; } if (end < real_end) { prot = 0; for(addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { prot |= page_get_flags(addr); } if (prot != 0) real_end -= qemu_host_page_size; } ret = 0; /* unmap what we can */ if (real_start < real_end) { if (RESERVED_VA) { mmap_reserve(real_start, real_end - real_start); } else { ret = munmap(g2h(real_start), real_end - real_start); } } if (ret == 0) page_set_flags(start, start + len, 0); mmap_unlock(); return ret; } abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size, abi_ulong new_size, unsigned long flags, abi_ulong new_addr) { int prot; void *host_addr; mmap_lock(); if (flags & MREMAP_FIXED) { host_addr = (void *) syscall(__NR_mremap, g2h(old_addr), old_size, new_size, flags, g2h(new_addr)); if (RESERVED_VA && host_addr != MAP_FAILED) { /* If new and old addresses overlap then the above mremap will already have failed with EINVAL. */ mmap_reserve(old_addr, old_size); } } else if (flags & MREMAP_MAYMOVE) { abi_ulong mmap_start; mmap_start = mmap_find_vma(0, new_size); if (mmap_start == -1) { errno = ENOMEM; host_addr = MAP_FAILED; } else { host_addr = (void *) syscall(__NR_mremap, g2h(old_addr), old_size, new_size, flags | MREMAP_FIXED, g2h(mmap_start)); if ( RESERVED_VA ) { mmap_reserve(old_addr, old_size); } } } else { int prot = 0; if (RESERVED_VA && old_size < new_size) { abi_ulong addr; for (addr = old_addr + old_size; addr < old_addr + new_size; addr++) { prot |= page_get_flags(addr); } } if (prot == 0) { host_addr = mremap(g2h(old_addr), old_size, new_size, flags); if (host_addr != MAP_FAILED && RESERVED_VA && old_size > new_size) { mmap_reserve(old_addr + old_size, new_size - old_size); } } else { errno = ENOMEM; host_addr = MAP_FAILED; } /* Check if address fits target address space */ if ((unsigned long)host_addr + new_size > (abi_ulong)-1) { /* Revert mremap() changes */ host_addr = mremap(g2h(old_addr), new_size, old_size, flags); errno = ENOMEM; host_addr = MAP_FAILED; } } if (host_addr == MAP_FAILED) { new_addr = -1; } else { new_addr = h2g(host_addr); prot = page_get_flags(old_addr); page_set_flags(old_addr, old_addr + old_size, 0); page_set_flags(new_addr, new_addr + new_size, prot | PAGE_VALID); } mmap_unlock(); return new_addr; } int target_msync(abi_ulong start, abi_ulong len, int flags) { abi_ulong end; if (start & ~TARGET_PAGE_MASK) return -EINVAL; len = TARGET_PAGE_ALIGN(len); end = start + len; if (end < start) return -EINVAL; if (end == start) return 0; start &= qemu_host_page_mask; return msync(g2h(start), end - start, flags); }