diff options
Diffstat (limited to 'bsd-user/mmap.c')
| -rw-r--r-- | bsd-user/mmap.c | 794 |
1 files changed, 794 insertions, 0 deletions
diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c new file mode 100644 index 000000000..13cb32dba --- /dev/null +++ b/bsd-user/mmap.c @@ -0,0 +1,794 @@ +/* + * mmap support for qemu + * + * Copyright (c) 2003 - 2008 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 "qemu/osdep.h" + +#include "qemu.h" +#include "qemu-common.h" + +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); + } +} + +bool have_mmap_lock(void) +{ + return mmap_lock_count > 0 ? true : false; +} + +/* 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); +} + +/* 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; + + qemu_log_mask(CPU_LOG_PAGE, "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' : '-'); + 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_untagged(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_untagged(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_untagged(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 + * + * mmap_frag can be called with a valid fd, if flags doesn't contain one of + * MAP_ANON, MAP_STACK, MAP_GUARD. If we need to map a page in those cases, we + * pass fd == -1. However, if flags contains MAP_GUARD then MAP_ANON cannot be + * added. + * + * * If fd is valid (not -1) we want to map the pages with MAP_ANON. + * * If flags contains MAP_GUARD we don't want to add MAP_ANON because it + * will be rejected. See kern_mmap's enforcing of constraints for MAP_GUARD + * in sys/vm/vm_mmap.c. + * * If flags contains MAP_ANON it doesn't matter if we add it or not. + * * If flags contains MAP_STACK, mmap adds MAP_ANON when called so doesn't + * matter if we add it or not either. See enforcing of constraints for + * MAP_STACK in kern_mmap. + * + * Don't add MAP_ANON for the flags that use fd == -1 without specifying the + * flags directly, with the assumption that future flags that require fd == -1 + * will also not require MAP_ANON. + */ +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_untagged(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. See also above. */ + void *p = mmap(host_start, qemu_host_page_size, prot, + flags | ((fd != -1) ? MAP_ANON : 0), -1, 0); + if (p == MAP_FAILED) + return -1; + prot1 = prot; + } + prot1 &= PAGE_BITS; + + prot_new = prot | prot1; + if (fd != -1) { + /* msync() won't work here, so we return an error if write is + possible while it is a shared mapping */ + if ((flags & TARGET_BSD_MAP_FLAGMASK) == 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_untagged(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 { + if (prot_new != prot1) { + mprotect(host_start, qemu_host_page_size, prot_new); + } + if (prot_new & PROT_WRITE) { + memset(g2h_untagged(start), 0, end - start); + } + } + return 0; +} + +#if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64 +# define TASK_UNMAPPED_BASE (1ul << 38) +#else +# define TASK_UNMAPPED_BASE 0x40000000 +#endif +abi_ulong mmap_next_start = TASK_UNMAPPED_BASE; + +unsigned long last_brk; + +/* + * 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 alignment) +{ + 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) + alignment; + 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 (end_addr - addr >= size) { + break; + } + addr -= qemu_host_page_size; + } + + if (start == mmap_next_start) { + mmap_next_start = addr; + } + /* addr is sufficiently low to align it up */ + if (alignment != 0) { + addr = (addr + alignment) & ~(alignment - 1); + } + return addr; +} + +/* + * 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. + */ +static abi_ulong mmap_find_vma_aligned(abi_ulong start, abi_ulong size, + abi_ulong alignment) +{ + void *ptr, *prev; + abi_ulong addr; + int flags; + 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); + + if (reserved_va) { + return mmap_find_vma_reserved(start, size, + (alignment != 0 ? 1 << alignment : 0)); + } + + addr = start; + wrapped = repeat = 0; + prev = 0; + flags = MAP_ANON | MAP_PRIVATE; + if (alignment != 0) { + flags |= MAP_ALIGNED(alignment); + } + + 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_untagged(addr), size, PROT_NONE, + flags, -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 = TARGET_PAGE_SIZE; + } else if (wrapped && addr >= start) { + return (abi_ulong)-1; + } + } +} + +abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) +{ + return mmap_find_vma_aligned(start, size, 0); +} + +/* NOTE: all the constants are the HOST ones */ +abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, + int flags, int fd, off_t offset) +{ + abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len; + + mmap_lock(); + if (qemu_loglevel_mask(CPU_LOG_PAGE)) { + qemu_log("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_ALIGNMENT_MASK) { + qemu_log("MAP_ALIGNED(%u) ", + (flags & MAP_ALIGNMENT_MASK) >> MAP_ALIGNMENT_SHIFT); + } + if (flags & MAP_GUARD) { + qemu_log("MAP_GUARD "); + } + if (flags & MAP_FIXED) { + qemu_log("MAP_FIXED "); + } + if (flags & MAP_ANON) { + qemu_log("MAP_ANON "); + } + if (flags & MAP_EXCL) { + qemu_log("MAP_EXCL "); + } + if (flags & MAP_PRIVATE) { + qemu_log("MAP_PRIVATE "); + } + if (flags & MAP_SHARED) { + qemu_log("MAP_SHARED "); + } + if (flags & MAP_NOCORE) { + qemu_log("MAP_NOCORE "); + } + if (flags & MAP_STACK) { + qemu_log("MAP_STACK "); + } + qemu_log("fd=%d offset=0x%lx\n", fd, offset); + } + + if ((flags & MAP_ANON) && fd != -1) { + errno = EINVAL; + goto fail; + } + if (flags & MAP_STACK) { + if ((fd != -1) || ((prot & (PROT_READ | PROT_WRITE)) != + (PROT_READ | PROT_WRITE))) { + errno = EINVAL; + goto fail; + } + } + if ((flags & MAP_GUARD) && (prot != PROT_NONE || fd != -1 || + offset != 0 || (flags & (MAP_SHARED | MAP_PRIVATE | + /* MAP_PREFAULT | */ /* MAP_PREFAULT not in mman.h */ + MAP_PREFAULT_READ | MAP_ANON | MAP_STACK)) != 0)) { + errno = EINVAL; + goto fail; + } + + if (offset & ~TARGET_PAGE_MASK) { + errno = EINVAL; + goto fail; + } + + if (len == 0) { + errno = EINVAL; + goto fail; + } + + /* Check for overflows */ + len = TARGET_PAGE_ALIGN(len); + if (len == 0) { + errno = ENOMEM; + goto fail; + } + + real_start = start & qemu_host_page_mask; + host_offset = offset & qemu_host_page_mask; + + /* + * If the user is asking for the kernel to find a location, do that + * before we truncate the length for mapping files below. + */ + if (!(flags & MAP_FIXED)) { + host_len = len + offset - host_offset; + host_len = HOST_PAGE_ALIGN(host_len); + if ((flags & MAP_ALIGNMENT_MASK) != 0) + start = mmap_find_vma_aligned(real_start, host_len, + (flags & MAP_ALIGNMENT_MASK) >> MAP_ALIGNMENT_SHIFT); + else + start = mmap_find_vma(real_start, host_len); + if (start == (abi_ulong)-1) { + errno = ENOMEM; + goto fail; + } + } + + /* + * 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 < qemu_host_page_size) && fd != -1) { + 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 = REAL_HOST_PAGE_ALIGN(sb.st_size - offset); + } + } + + if (!(flags & MAP_FIXED)) { + unsigned long host_start; + void *p; + + host_len = len + offset - host_offset; + host_len = HOST_PAGE_ALIGN(host_len); + + /* + * 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_untagged(start), host_len, prot, + flags | MAP_FIXED | ((fd != -1) ? MAP_ANON : 0), -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 (fd != -1) { + p = mmap(g2h_untagged(start), len, prot, + flags | MAP_FIXED, fd, host_offset); + if (p == MAP_FAILED) { + munmap(g2h_untagged(start), host_len); + goto fail; + } + 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 (!guest_range_valid_untagged(start, len)) { + errno = EINVAL; + goto fail; + } + + /* + * worst case: we cannot map the file because the offset is not + * aligned, so we read it + */ + if (fd != -1 && + (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 & TARGET_BSD_MAP_FLAGMASK) == MAP_SHARED && + (prot & PROT_WRITE)) { + errno = EINVAL; + goto fail; + } + retaddr = target_mmap(start, len, prot | PROT_WRITE, + MAP_FIXED | MAP_PRIVATE | MAP_ANON, + -1, 0); + if (retaddr == -1) + goto fail; + if (pread(fd, g2h_untagged(start), len, offset) == -1) { + goto fail; + } + if (!(prot & PROT_WRITE)) { + ret = target_mprotect(start, len, prot); + assert(ret == 0); + } + goto the_end; + } + + /* Reject the mapping if any page within the range is mapped */ + if ((flags & MAP_EXCL) && page_check_range(start, len, 0) < 0) { + errno = EINVAL; + goto fail; + } + + /* 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, 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_ANON) + offset1 = 0; + else + offset1 = offset + real_start - start; + p = mmap(g2h_untagged(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 + tb_invalidate_phys_range(start, start + len); + 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_untagged(real_start), real_end - real_start, PROT_NONE, + MAP_FIXED | MAP_ANON | MAP_PRIVATE, -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_untagged(real_start), real_end - real_start); + } + } + + if (ret == 0) { + page_set_flags(start, start + len, 0); + tb_invalidate_phys_range(start, start + len); + } + mmap_unlock(); + return ret; +} + +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_untagged(start), end - start, flags); +} |