| /* |
| * 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 "qemu/osdep.h" |
| #include "trace.h" |
| #include "exec/log.h" |
| #include "qemu.h" |
| #include "user-internals.h" |
| #include "user-mmap.h" |
| #include "target_mman.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) |
| { |
| assert(mmap_lock_count > 0); |
| 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); |
| } |
| } |
| |
| /* |
| * Validate target prot bitmask. |
| * Return the prot bitmask for the host in *HOST_PROT. |
| * Return 0 if the target prot bitmask is invalid, otherwise |
| * the internal qemu page_flags (which will include PAGE_VALID). |
| */ |
| static int validate_prot_to_pageflags(int prot) |
| { |
| int valid = PROT_READ | PROT_WRITE | PROT_EXEC | TARGET_PROT_SEM; |
| int page_flags = (prot & PAGE_BITS) | PAGE_VALID; |
| |
| #ifdef TARGET_AARCH64 |
| { |
| ARMCPU *cpu = ARM_CPU(thread_cpu); |
| |
| /* |
| * The PROT_BTI bit is only accepted if the cpu supports the feature. |
| * Since this is the unusual case, don't bother checking unless |
| * the bit has been requested. If set and valid, record the bit |
| * within QEMU's page_flags. |
| */ |
| if ((prot & TARGET_PROT_BTI) && cpu_isar_feature(aa64_bti, cpu)) { |
| valid |= TARGET_PROT_BTI; |
| page_flags |= PAGE_BTI; |
| } |
| /* Similarly for the PROT_MTE bit. */ |
| if ((prot & TARGET_PROT_MTE) && cpu_isar_feature(aa64_mte, cpu)) { |
| valid |= TARGET_PROT_MTE; |
| page_flags |= PAGE_MTE; |
| } |
| } |
| #elif defined(TARGET_HPPA) |
| valid |= PROT_GROWSDOWN | PROT_GROWSUP; |
| #endif |
| |
| return prot & ~valid ? 0 : page_flags; |
| } |
| |
| /* |
| * For the host, we need not pass anything except read/write/exec. |
| * While PROT_SEM is allowed by all hosts, it is also ignored, so |
| * don't bother transforming guest bit to host bit. Any other |
| * target-specific prot bits will not be understood by the host |
| * and will need to be encoded into page_flags for qemu emulation. |
| * |
| * Pages that are executable by the guest will never be executed |
| * by the host, but the host will need to be able to read them. |
| */ |
| static int target_to_host_prot(int prot) |
| { |
| return (prot & (PROT_READ | PROT_WRITE)) | |
| (prot & PROT_EXEC ? PROT_READ : 0); |
| } |
| |
| /* NOTE: all the constants are the HOST ones, but addresses are target. */ |
| int target_mprotect(abi_ulong start, abi_ulong len, int target_prot) |
| { |
| abi_ulong starts[3]; |
| abi_ulong lens[3]; |
| int prots[3]; |
| abi_ulong host_start, host_last, last; |
| int prot1, ret, page_flags, nranges; |
| |
| trace_target_mprotect(start, len, target_prot); |
| |
| if ((start & ~TARGET_PAGE_MASK) != 0) { |
| return -TARGET_EINVAL; |
| } |
| page_flags = validate_prot_to_pageflags(target_prot); |
| if (!page_flags) { |
| return -TARGET_EINVAL; |
| } |
| if (len == 0) { |
| return 0; |
| } |
| len = TARGET_PAGE_ALIGN(len); |
| if (!guest_range_valid_untagged(start, len)) { |
| return -TARGET_ENOMEM; |
| } |
| |
| last = start + len - 1; |
| host_start = start & qemu_host_page_mask; |
| host_last = HOST_PAGE_ALIGN(last) - 1; |
| nranges = 0; |
| |
| mmap_lock(); |
| |
| if (host_last - host_start < qemu_host_page_size) { |
| /* Single host page contains all guest pages: sum the prot. */ |
| prot1 = target_prot; |
| for (abi_ulong a = host_start; a < start; a += TARGET_PAGE_SIZE) { |
| prot1 |= page_get_flags(a); |
| } |
| for (abi_ulong a = last; a < host_last; a += TARGET_PAGE_SIZE) { |
| prot1 |= page_get_flags(a + 1); |
| } |
| starts[nranges] = host_start; |
| lens[nranges] = qemu_host_page_size; |
| prots[nranges] = prot1; |
| nranges++; |
| } else { |
| if (host_start < start) { |
| /* Host page contains more than one guest page: sum the prot. */ |
| prot1 = target_prot; |
| for (abi_ulong a = host_start; a < start; a += TARGET_PAGE_SIZE) { |
| prot1 |= page_get_flags(a); |
| } |
| /* If the resulting sum differs, create a new range. */ |
| if (prot1 != target_prot) { |
| starts[nranges] = host_start; |
| lens[nranges] = qemu_host_page_size; |
| prots[nranges] = prot1; |
| nranges++; |
| host_start += qemu_host_page_size; |
| } |
| } |
| |
| if (last < host_last) { |
| /* Host page contains more than one guest page: sum the prot. */ |
| prot1 = target_prot; |
| for (abi_ulong a = last; a < host_last; a += TARGET_PAGE_SIZE) { |
| prot1 |= page_get_flags(a + 1); |
| } |
| /* If the resulting sum differs, create a new range. */ |
| if (prot1 != target_prot) { |
| host_last -= qemu_host_page_size; |
| starts[nranges] = host_last + 1; |
| lens[nranges] = qemu_host_page_size; |
| prots[nranges] = prot1; |
| nranges++; |
| } |
| } |
| |
| /* Create a range for the middle, if any remains. */ |
| if (host_start < host_last) { |
| starts[nranges] = host_start; |
| lens[nranges] = host_last - host_start + 1; |
| prots[nranges] = target_prot; |
| nranges++; |
| } |
| } |
| |
| for (int i = 0; i < nranges; ++i) { |
| ret = mprotect(g2h_untagged(starts[i]), lens[i], |
| target_to_host_prot(prots[i])); |
| if (ret != 0) { |
| goto error; |
| } |
| } |
| |
| page_set_flags(start, last, page_flags); |
| ret = 0; |
| |
| error: |
| mmap_unlock(); |
| return ret; |
| } |
| |
| /* map an incomplete host page */ |
| static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last, |
| int prot, int flags, int fd, off_t offset) |
| { |
| abi_ulong real_last; |
| void *host_start; |
| int prot_old, prot_new; |
| int host_prot_old, host_prot_new; |
| |
| if (!(flags & MAP_ANONYMOUS) |
| && (flags & MAP_TYPE) == MAP_SHARED |
| && (prot & PROT_WRITE)) { |
| /* |
| * msync() won't work with the partial page, so we return an |
| * error if write is possible while it is a shared mapping. |
| */ |
| errno = EINVAL; |
| return false; |
| } |
| |
| real_last = real_start + qemu_host_page_size - 1; |
| host_start = g2h_untagged(real_start); |
| |
| /* Get the protection of the target pages outside the mapping. */ |
| prot_old = 0; |
| for (abi_ulong a = real_start; a < start; a += TARGET_PAGE_SIZE) { |
| prot_old |= page_get_flags(a); |
| } |
| for (abi_ulong a = real_last; a > last; a -= TARGET_PAGE_SIZE) { |
| prot_old |= page_get_flags(a); |
| } |
| |
| if (prot_old == 0) { |
| /* |
| * Since !(prot_old & PAGE_VALID), there were no guest pages |
| * outside of the fragment we need to map. Allocate a new host |
| * page to cover, discarding whatever else may have been present. |
| */ |
| void *p = mmap(host_start, qemu_host_page_size, |
| target_to_host_prot(prot), |
| flags | MAP_ANONYMOUS, -1, 0); |
| if (p != host_start) { |
| if (p != MAP_FAILED) { |
| munmap(p, qemu_host_page_size); |
| errno = EEXIST; |
| } |
| return false; |
| } |
| prot_old = prot; |
| } |
| prot_new = prot | prot_old; |
| |
| host_prot_old = target_to_host_prot(prot_old); |
| host_prot_new = target_to_host_prot(prot_new); |
| |
| /* Adjust protection to be able to write. */ |
| if (!(host_prot_old & PROT_WRITE)) { |
| host_prot_old |= PROT_WRITE; |
| mprotect(host_start, qemu_host_page_size, host_prot_old); |
| } |
| |
| /* Read or zero the new guest pages. */ |
| if (flags & MAP_ANONYMOUS) { |
| memset(g2h_untagged(start), 0, last - start + 1); |
| } else { |
| if (pread(fd, g2h_untagged(start), last - start + 1, offset) == -1) { |
| return false; |
| } |
| } |
| |
| /* Put final protection */ |
| if (host_prot_new != host_prot_old) { |
| mprotect(host_start, qemu_host_page_size, host_prot_new); |
| } |
| return true; |
| } |
| |
| abi_ulong task_unmapped_base; |
| abi_ulong elf_et_dyn_base; |
| abi_ulong mmap_next_start; |
| |
| /* |
| * 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 align) |
| { |
| target_ulong ret; |
| |
| ret = page_find_range_empty(start, reserved_va, size, align); |
| if (ret == -1 && start > mmap_min_addr) { |
| /* Restart at the beginning of the address space. */ |
| ret = page_find_range_empty(mmap_min_addr, start - 1, size, align); |
| } |
| |
| return ret; |
| } |
| |
| /* |
| * 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, abi_ulong align) |
| { |
| void *ptr, *prev; |
| abi_ulong addr; |
| int wrapped, repeat; |
| |
| align = MAX(align, qemu_host_page_size); |
| |
| /* If 'start' == 0, then a default start address is used. */ |
| if (start == 0) { |
| start = mmap_next_start; |
| } else { |
| start &= qemu_host_page_mask; |
| } |
| start = ROUND_UP(start, align); |
| |
| size = HOST_PAGE_ALIGN(size); |
| |
| if (reserved_va) { |
| return mmap_find_vma_reserved(start, size, align); |
| } |
| |
| 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_untagged(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 & (align - 1)) == 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 = ROUND_UP(addr, align); |
| break; |
| case 1: |
| /* |
| * Sometimes the kernel decides to perform the allocation |
| * at the top end of memory instead. |
| */ |
| addr &= -align; |
| 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 target_prot, |
| int flags, int fd, off_t offset) |
| { |
| abi_ulong ret, last, real_start, real_last, retaddr, host_len; |
| abi_ulong passthrough_start = -1, passthrough_last = 0; |
| int page_flags; |
| off_t host_offset; |
| |
| mmap_lock(); |
| trace_target_mmap(start, len, target_prot, flags, fd, offset); |
| |
| if (!len) { |
| errno = EINVAL; |
| goto fail; |
| } |
| |
| page_flags = validate_prot_to_pageflags(target_prot); |
| if (!page_flags) { |
| errno = EINVAL; |
| goto fail; |
| } |
| |
| /* Also check for overflows... */ |
| len = TARGET_PAGE_ALIGN(len); |
| if (!len) { |
| errno = ENOMEM; |
| goto fail; |
| } |
| |
| if (offset & ~TARGET_PAGE_MASK) { |
| errno = EINVAL; |
| goto fail; |
| } |
| |
| /* |
| * If we're mapping shared memory, ensure we generate code for parallel |
| * execution and flush old translations. This will work up to the level |
| * supported by the host -- anything that requires EXCP_ATOMIC will not |
| * be atomic with respect to an external process. |
| */ |
| if (flags & MAP_SHARED) { |
| CPUState *cpu = thread_cpu; |
| if (!(cpu->tcg_cflags & CF_PARALLEL)) { |
| cpu->tcg_cflags |= CF_PARALLEL; |
| tb_flush(cpu); |
| } |
| } |
| |
| 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 | MAP_FIXED_NOREPLACE))) { |
| host_len = len + offset - host_offset; |
| host_len = HOST_PAGE_ALIGN(host_len); |
| start = mmap_find_vma(real_start, host_len, TARGET_PAGE_SIZE); |
| 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) && |
| !(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 = REAL_HOST_PAGE_ALIGN(sb.st_size - offset); |
| } |
| } |
| |
| if (!(flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))) { |
| uintptr_t host_start; |
| int host_prot; |
| void *p; |
| |
| host_len = len + offset - host_offset; |
| host_len = HOST_PAGE_ALIGN(host_len); |
| host_prot = target_to_host_prot(target_prot); |
| |
| /* |
| * 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, host_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 = (uintptr_t)p; |
| if (!(flags & MAP_ANONYMOUS)) { |
| p = mmap(g2h_untagged(start), len, host_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); |
| last = start + len - 1; |
| passthrough_start = start; |
| passthrough_last = last; |
| } else { |
| if (start & ~TARGET_PAGE_MASK) { |
| errno = EINVAL; |
| goto fail; |
| } |
| last = start + len - 1; |
| real_last = HOST_PAGE_ALIGN(last) - 1; |
| |
| /* |
| * 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 (last < start || !guest_range_valid_untagged(start, len)) { |
| errno = ENOMEM; |
| goto fail; |
| } |
| |
| if (flags & MAP_FIXED_NOREPLACE) { |
| /* Validate that the chosen range is empty. */ |
| if (!page_check_range_empty(start, last)) { |
| errno = EEXIST; |
| goto fail; |
| } |
| |
| /* |
| * With reserved_va, the entire address space is mmaped in the |
| * host to ensure it isn't accidentally used for something else. |
| * We have just checked that the guest address is not mapped |
| * within the guest, but need to replace the host reservation. |
| * |
| * Without reserved_va, despite the guest address check above, |
| * keep MAP_FIXED_NOREPLACE so that the guest does not overwrite |
| * any host address mappings. |
| */ |
| if (reserved_va) { |
| flags = (flags & ~MAP_FIXED_NOREPLACE) | MAP_FIXED; |
| } |
| } |
| |
| /* |
| * 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 |
| && (target_prot & PROT_WRITE)) { |
| errno = EINVAL; |
| goto fail; |
| } |
| retaddr = target_mmap(start, len, target_prot | PROT_WRITE, |
| (flags & (MAP_FIXED | MAP_FIXED_NOREPLACE)) |
| | MAP_PRIVATE | MAP_ANONYMOUS, |
| -1, 0); |
| if (retaddr == -1) { |
| goto fail; |
| } |
| if (pread(fd, g2h_untagged(start), len, offset) == -1) { |
| goto fail; |
| } |
| if (!(target_prot & PROT_WRITE)) { |
| ret = target_mprotect(start, len, target_prot); |
| assert(ret == 0); |
| } |
| goto the_end; |
| } |
| |
| /* handle the start of the mapping */ |
| if (start > real_start) { |
| if (real_last == real_start + qemu_host_page_size - 1) { |
| /* one single host page */ |
| if (!mmap_frag(real_start, start, last, |
| target_prot, flags, fd, offset)) { |
| goto fail; |
| } |
| goto the_end1; |
| } |
| if (!mmap_frag(real_start, start, |
| real_start + qemu_host_page_size - 1, |
| target_prot, flags, fd, offset)) { |
| goto fail; |
| } |
| real_start += qemu_host_page_size; |
| } |
| /* handle the end of the mapping */ |
| if (last < real_last) { |
| abi_ulong real_page = real_last - qemu_host_page_size + 1; |
| if (!mmap_frag(real_page, real_page, last, |
| target_prot, flags, fd, |
| offset + real_page - start)) { |
| goto fail; |
| } |
| real_last -= qemu_host_page_size; |
| } |
| |
| /* map the middle (easier) */ |
| if (real_start < real_last) { |
| void *p, *want_p; |
| off_t offset1; |
| size_t len1; |
| |
| if (flags & MAP_ANONYMOUS) { |
| offset1 = 0; |
| } else { |
| offset1 = offset + real_start - start; |
| } |
| len1 = real_last - real_start + 1; |
| want_p = g2h_untagged(real_start); |
| |
| p = mmap(want_p, len1, target_to_host_prot(target_prot), |
| flags, fd, offset1); |
| if (p != want_p) { |
| if (p != MAP_FAILED) { |
| munmap(p, len1); |
| errno = EEXIST; |
| } |
| goto fail; |
| } |
| passthrough_start = real_start; |
| passthrough_last = real_last; |
| } |
| } |
| the_end1: |
| if (flags & MAP_ANONYMOUS) { |
| page_flags |= PAGE_ANON; |
| } |
| page_flags |= PAGE_RESET; |
| if (passthrough_start > passthrough_last) { |
| page_set_flags(start, last, page_flags); |
| } else { |
| if (start < passthrough_start) { |
| page_set_flags(start, passthrough_start - 1, page_flags); |
| } |
| page_set_flags(passthrough_start, passthrough_last, |
| page_flags | PAGE_PASSTHROUGH); |
| if (passthrough_last < last) { |
| page_set_flags(passthrough_last + 1, last, page_flags); |
| } |
| } |
| the_end: |
| trace_target_mmap_complete(start); |
| if (qemu_loglevel_mask(CPU_LOG_PAGE)) { |
| FILE *f = qemu_log_trylock(); |
| if (f) { |
| fprintf(f, "page layout changed following mmap\n"); |
| page_dump(f); |
| qemu_log_unlock(f); |
| } |
| } |
| mmap_unlock(); |
| return start; |
| fail: |
| mmap_unlock(); |
| return -1; |
| } |
| |
| static void mmap_reserve_or_unmap(abi_ulong start, abi_ulong len) |
| { |
| abi_ulong real_start; |
| abi_ulong real_last; |
| abi_ulong real_len; |
| abi_ulong last; |
| abi_ulong a; |
| void *host_start; |
| int prot; |
| |
| last = start + len - 1; |
| real_start = start & qemu_host_page_mask; |
| real_last = HOST_PAGE_ALIGN(last) - 1; |
| |
| /* |
| * If guest pages remain on the first or last host pages, |
| * adjust the deallocation to retain those guest pages. |
| * The single page special case is required for the last page, |
| * lest real_start overflow to zero. |
| */ |
| if (real_last - real_start < qemu_host_page_size) { |
| prot = 0; |
| for (a = real_start; a < start; a += TARGET_PAGE_SIZE) { |
| prot |= page_get_flags(a); |
| } |
| for (a = last; a < real_last; a += TARGET_PAGE_SIZE) { |
| prot |= page_get_flags(a + 1); |
| } |
| if (prot != 0) { |
| return; |
| } |
| } else { |
| for (prot = 0, a = real_start; a < start; a += TARGET_PAGE_SIZE) { |
| prot |= page_get_flags(a); |
| } |
| if (prot != 0) { |
| real_start += qemu_host_page_size; |
| } |
| |
| for (prot = 0, a = last; a < real_last; a += TARGET_PAGE_SIZE) { |
| prot |= page_get_flags(a + 1); |
| } |
| if (prot != 0) { |
| real_last -= qemu_host_page_size; |
| } |
| |
| if (real_last < real_start) { |
| return; |
| } |
| } |
| |
| real_len = real_last - real_start + 1; |
| host_start = g2h_untagged(real_start); |
| |
| if (reserved_va) { |
| void *ptr = mmap(host_start, real_len, PROT_NONE, |
| MAP_FIXED | MAP_ANONYMOUS |
| | MAP_PRIVATE | MAP_NORESERVE, -1, 0); |
| assert(ptr == host_start); |
| } else { |
| int ret = munmap(host_start, real_len); |
| assert(ret == 0); |
| } |
| } |
| |
| int target_munmap(abi_ulong start, abi_ulong len) |
| { |
| trace_target_munmap(start, len); |
| |
| if (start & ~TARGET_PAGE_MASK) { |
| return -TARGET_EINVAL; |
| } |
| len = TARGET_PAGE_ALIGN(len); |
| if (len == 0 || !guest_range_valid_untagged(start, len)) { |
| return -TARGET_EINVAL; |
| } |
| |
| mmap_lock(); |
| mmap_reserve_or_unmap(start, len); |
| page_set_flags(start, start + len - 1, 0); |
| mmap_unlock(); |
| |
| return 0; |
| } |
| |
| 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; |
| |
| if (!guest_range_valid_untagged(old_addr, old_size) || |
| ((flags & MREMAP_FIXED) && |
| !guest_range_valid_untagged(new_addr, new_size)) || |
| ((flags & MREMAP_MAYMOVE) == 0 && |
| !guest_range_valid_untagged(old_addr, new_size))) { |
| errno = ENOMEM; |
| return -1; |
| } |
| |
| mmap_lock(); |
| |
| if (flags & MREMAP_FIXED) { |
| host_addr = mremap(g2h_untagged(old_addr), old_size, new_size, |
| flags, g2h_untagged(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_or_unmap(old_addr, old_size); |
| } |
| } else if (flags & MREMAP_MAYMOVE) { |
| abi_ulong mmap_start; |
| |
| mmap_start = mmap_find_vma(0, new_size, TARGET_PAGE_SIZE); |
| |
| if (mmap_start == -1) { |
| errno = ENOMEM; |
| host_addr = MAP_FAILED; |
| } else { |
| host_addr = mremap(g2h_untagged(old_addr), old_size, new_size, |
| flags | MREMAP_FIXED, |
| g2h_untagged(mmap_start)); |
| if (reserved_va) { |
| mmap_reserve_or_unmap(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_untagged(old_addr), |
| old_size, new_size, flags); |
| |
| if (host_addr != MAP_FAILED) { |
| /* Check if address fits target address space */ |
| if (!guest_range_valid_untagged(h2g(host_addr), new_size)) { |
| /* Revert mremap() changes */ |
| host_addr = mremap(g2h_untagged(old_addr), |
| new_size, old_size, flags); |
| errno = ENOMEM; |
| host_addr = MAP_FAILED; |
| } else if (reserved_va && old_size > new_size) { |
| mmap_reserve_or_unmap(old_addr + old_size, |
| old_size - new_size); |
| } |
| } |
| } else { |
| 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 - 1, 0); |
| page_set_flags(new_addr, new_addr + new_size - 1, |
| prot | PAGE_VALID | PAGE_RESET); |
| } |
| mmap_unlock(); |
| return new_addr; |
| } |
| |
| abi_long target_madvise(abi_ulong start, abi_ulong len_in, int advice) |
| { |
| abi_ulong len; |
| int ret = 0; |
| |
| if (start & ~TARGET_PAGE_MASK) { |
| return -TARGET_EINVAL; |
| } |
| if (len_in == 0) { |
| return 0; |
| } |
| len = TARGET_PAGE_ALIGN(len_in); |
| if (len == 0 || !guest_range_valid_untagged(start, len)) { |
| return -TARGET_EINVAL; |
| } |
| |
| /* Translate for some architectures which have different MADV_xxx values */ |
| switch (advice) { |
| case TARGET_MADV_DONTNEED: /* alpha */ |
| advice = MADV_DONTNEED; |
| break; |
| case TARGET_MADV_WIPEONFORK: /* parisc */ |
| advice = MADV_WIPEONFORK; |
| break; |
| case TARGET_MADV_KEEPONFORK: /* parisc */ |
| advice = MADV_KEEPONFORK; |
| break; |
| /* we do not care about the other MADV_xxx values yet */ |
| } |
| |
| /* |
| * Most advice values are hints, so ignoring and returning success is ok. |
| * |
| * However, some advice values such as MADV_DONTNEED, MADV_WIPEONFORK and |
| * MADV_KEEPONFORK are not hints and need to be emulated. |
| * |
| * A straight passthrough for those may not be safe because qemu sometimes |
| * turns private file-backed mappings into anonymous mappings. |
| * If all guest pages have PAGE_PASSTHROUGH set, mappings have the |
| * same semantics for the host as for the guest. |
| * |
| * We pass through MADV_WIPEONFORK and MADV_KEEPONFORK if possible and |
| * return failure if not. |
| * |
| * MADV_DONTNEED is passed through as well, if possible. |
| * If passthrough isn't possible, we nevertheless (wrongly!) return |
| * success, which is broken but some userspace programs fail to work |
| * otherwise. Completely implementing such emulation is quite complicated |
| * though. |
| */ |
| mmap_lock(); |
| switch (advice) { |
| case MADV_WIPEONFORK: |
| case MADV_KEEPONFORK: |
| ret = -EINVAL; |
| /* fall through */ |
| case MADV_DONTNEED: |
| if (page_check_range(start, len, PAGE_PASSTHROUGH)) { |
| ret = get_errno(madvise(g2h_untagged(start), len, advice)); |
| if ((advice == MADV_DONTNEED) && (ret == 0)) { |
| page_reset_target_data(start, start + len - 1); |
| } |
| } |
| } |
| mmap_unlock(); |
| |
| return ret; |
| } |
