| /* |
| * 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 <sys/shm.h> |
| #include "trace.h" |
| #include "exec/log.h" |
| #include "exec/page-protection.h" |
| #include "qemu.h" |
| #include "user-internals.h" |
| #include "user-mmap.h" |
| #include "target_mman.h" |
| #include "qemu/interval-tree.h" |
| |
| #ifdef TARGET_ARM |
| #include "target/arm/cpu-features.h" |
| #endif |
| |
| 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); |
| } |
| } |
| |
| /* Protected by mmap_lock. */ |
| static IntervalTreeRoot shm_regions; |
| |
| static void shm_region_add(abi_ptr start, abi_ptr last) |
| { |
| IntervalTreeNode *i = g_new0(IntervalTreeNode, 1); |
| |
| i->start = start; |
| i->last = last; |
| interval_tree_insert(i, &shm_regions); |
| } |
| |
| static abi_ptr shm_region_find(abi_ptr start) |
| { |
| IntervalTreeNode *i; |
| |
| for (i = interval_tree_iter_first(&shm_regions, start, start); i; |
| i = interval_tree_iter_next(i, start, start)) { |
| if (i->start == start) { |
| return i->last; |
| } |
| } |
| return 0; |
| } |
| |
| static void shm_region_rm_complete(abi_ptr start, abi_ptr last) |
| { |
| IntervalTreeNode *i, *n; |
| |
| for (i = interval_tree_iter_first(&shm_regions, start, last); i; i = n) { |
| n = interval_tree_iter_next(i, start, last); |
| if (i->start >= start && i->last <= last) { |
| interval_tree_remove(i, &shm_regions); |
| g_free(i); |
| } |
| } |
| } |
| |
| /* |
| * 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_RWX) | 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) |
| { |
| int host_page_size = qemu_real_host_page_size(); |
| 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 & -host_page_size; |
| host_last = ROUND_UP(last, host_page_size) - 1; |
| nranges = 0; |
| |
| mmap_lock(); |
| |
| if (host_last - host_start < 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] = 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] = host_page_size; |
| prots[nranges] = prot1; |
| nranges++; |
| host_start += 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 -= host_page_size; |
| starts[nranges] = host_last + 1; |
| lens[nranges] = 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; |
| } |
| |
| /* |
| * Perform munmap on behalf of the target, with host parameters. |
| * If reserved_va, we must replace the memory reservation. |
| */ |
| static int do_munmap(void *addr, size_t len) |
| { |
| if (reserved_va) { |
| void *ptr = mmap(addr, len, PROT_NONE, |
| MAP_FIXED | MAP_ANONYMOUS |
| | MAP_PRIVATE | MAP_NORESERVE, -1, 0); |
| return ptr == addr ? 0 : -1; |
| } |
| return munmap(addr, len); |
| } |
| |
| /* |
| * Map an incomplete host page. |
| * |
| * Here be dragons. This case will not work if there is an existing |
| * overlapping host page, which is file mapped, and for which the mapping |
| * is beyond the end of the file. In that case, we will see SIGBUS when |
| * trying to write a portion of this page. |
| * |
| * FIXME: Work around this with a temporary signal handler and longjmp. |
| */ |
| static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last, |
| int prot, int flags, int fd, off_t offset) |
| { |
| int host_page_size = qemu_real_host_page_size(); |
| 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 + 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, host_page_size, |
| target_to_host_prot(prot), |
| flags | MAP_ANONYMOUS, -1, 0); |
| if (p != host_start) { |
| if (p != MAP_FAILED) { |
| do_munmap(p, 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, 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, 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) |
| { |
| int host_page_size = qemu_real_host_page_size(); |
| void *ptr, *prev; |
| abi_ulong addr; |
| int wrapped, repeat; |
| |
| align = MAX(align, host_page_size); |
| |
| /* If 'start' == 0, then a default start address is used. */ |
| if (start == 0) { |
| start = mmap_next_start; |
| } else { |
| start &= -host_page_size; |
| } |
| start = ROUND_UP(start, align); |
| size = ROUND_UP(size, host_page_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; |
| } |
| } |
| } |
| |
| /* |
| * Record a successful mmap within the user-exec interval tree. |
| */ |
| static abi_long mmap_end(abi_ulong start, abi_ulong last, |
| abi_ulong passthrough_start, |
| abi_ulong passthrough_last, |
| int flags, int page_flags) |
| { |
| 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); |
| } |
| } |
| shm_region_rm_complete(start, last); |
| 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); |
| } |
| } |
| return start; |
| } |
| |
| /* |
| * Special case host page size == target page size, |
| * where there are no edge conditions. |
| */ |
| static abi_long mmap_h_eq_g(abi_ulong start, abi_ulong len, |
| int host_prot, int flags, int page_flags, |
| int fd, off_t offset) |
| { |
| void *p, *want_p = NULL; |
| abi_ulong last; |
| |
| if (start || (flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))) { |
| want_p = g2h_untagged(start); |
| } |
| |
| p = mmap(want_p, len, host_prot, flags, fd, offset); |
| if (p == MAP_FAILED) { |
| return -1; |
| } |
| /* If the host kernel does not support MAP_FIXED_NOREPLACE, emulate. */ |
| if ((flags & MAP_FIXED_NOREPLACE) && p != want_p) { |
| do_munmap(p, len); |
| errno = EEXIST; |
| return -1; |
| } |
| |
| start = h2g(p); |
| last = start + len - 1; |
| return mmap_end(start, last, start, last, flags, page_flags); |
| } |
| |
| /* |
| * Special case host page size < target page size. |
| * |
| * The two special cases are increased guest alignment, and mapping |
| * past the end of a file. |
| * |
| * 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. |
| * |
| * This workaround only works for files that do not change. |
| * If the file is later extended (e.g. ftruncate), the SIGBUS |
| * vanishes and the proper behaviour is that changes within the |
| * anon page should be reflected in the file. |
| * |
| * However, this case is rather common with executable images, |
| * so the workaround is important for even trivial tests, whereas |
| * the mmap of of a file being extended is less common. |
| */ |
| static abi_long mmap_h_lt_g(abi_ulong start, abi_ulong len, int host_prot, |
| int mmap_flags, int page_flags, int fd, |
| off_t offset, int host_page_size) |
| { |
| void *p, *want_p = NULL; |
| off_t fileend_adj = 0; |
| int flags = mmap_flags; |
| abi_ulong last, pass_last; |
| |
| if (start || (flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))) { |
| want_p = g2h_untagged(start); |
| } |
| |
| if (!(flags & MAP_ANONYMOUS)) { |
| struct stat sb; |
| |
| if (fstat(fd, &sb) == -1) { |
| return -1; |
| } |
| if (offset >= sb.st_size) { |
| /* |
| * The entire map is beyond the end of the file. |
| * Transform it to an anonymous mapping. |
| */ |
| flags |= MAP_ANONYMOUS; |
| fd = -1; |
| offset = 0; |
| } else if (offset + len > sb.st_size) { |
| /* |
| * A portion of the map is beyond the end of the file. |
| * Truncate the file portion of the allocation. |
| */ |
| fileend_adj = offset + len - sb.st_size; |
| } |
| } |
| |
| if (flags & (MAP_FIXED | MAP_FIXED_NOREPLACE)) { |
| if (fileend_adj) { |
| p = mmap(want_p, len, host_prot, flags | MAP_ANONYMOUS, -1, 0); |
| } else { |
| p = mmap(want_p, len, host_prot, flags, fd, offset); |
| } |
| if (p != want_p) { |
| if (p != MAP_FAILED) { |
| /* Host does not support MAP_FIXED_NOREPLACE: emulate. */ |
| do_munmap(p, len); |
| errno = EEXIST; |
| } |
| return -1; |
| } |
| |
| if (fileend_adj) { |
| void *t = mmap(p, len - fileend_adj, host_prot, |
| (flags & ~MAP_FIXED_NOREPLACE) | MAP_FIXED, |
| fd, offset); |
| |
| if (t == MAP_FAILED) { |
| int save_errno = errno; |
| |
| /* |
| * We failed a map over the top of the successful anonymous |
| * mapping above. The only failure mode is running out of VMAs, |
| * and there's nothing that we can do to detect that earlier. |
| * If we have replaced an existing mapping with MAP_FIXED, |
| * then we cannot properly recover. It's a coin toss whether |
| * it would be better to exit or continue here. |
| */ |
| if (!(flags & MAP_FIXED_NOREPLACE) && |
| !page_check_range_empty(start, start + len - 1)) { |
| qemu_log("QEMU target_mmap late failure: %s", |
| strerror(save_errno)); |
| } |
| |
| do_munmap(want_p, len); |
| errno = save_errno; |
| return -1; |
| } |
| } |
| } else { |
| size_t host_len, part_len; |
| |
| /* |
| * Take care to align the host memory. Perform a larger anonymous |
| * allocation and extract the aligned portion. Remap the file on |
| * top of that. |
| */ |
| host_len = len + TARGET_PAGE_SIZE - host_page_size; |
| p = mmap(want_p, host_len, host_prot, flags | MAP_ANONYMOUS, -1, 0); |
| if (p == MAP_FAILED) { |
| return -1; |
| } |
| |
| part_len = (uintptr_t)p & (TARGET_PAGE_SIZE - 1); |
| if (part_len) { |
| part_len = TARGET_PAGE_SIZE - part_len; |
| do_munmap(p, part_len); |
| p += part_len; |
| host_len -= part_len; |
| } |
| if (len < host_len) { |
| do_munmap(p + len, host_len - len); |
| } |
| |
| if (!(flags & MAP_ANONYMOUS)) { |
| void *t = mmap(p, len - fileend_adj, host_prot, |
| flags | MAP_FIXED, fd, offset); |
| |
| if (t == MAP_FAILED) { |
| int save_errno = errno; |
| do_munmap(p, len); |
| errno = save_errno; |
| return -1; |
| } |
| } |
| |
| start = h2g(p); |
| } |
| |
| last = start + len - 1; |
| if (fileend_adj) { |
| pass_last = ROUND_UP(last - fileend_adj, host_page_size) - 1; |
| } else { |
| pass_last = last; |
| } |
| return mmap_end(start, last, start, pass_last, mmap_flags, page_flags); |
| } |
| |
| /* |
| * Special case host page size > target page size. |
| * |
| * The two special cases are address and file offsets that are valid |
| * for the guest that cannot be directly represented by the host. |
| */ |
| static abi_long mmap_h_gt_g(abi_ulong start, abi_ulong len, |
| int target_prot, int host_prot, |
| int flags, int page_flags, int fd, |
| off_t offset, int host_page_size) |
| { |
| void *p, *want_p = NULL; |
| off_t host_offset = offset & -host_page_size; |
| abi_ulong last, real_start, real_last; |
| bool misaligned_offset = false; |
| size_t host_len; |
| |
| if (start || (flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))) { |
| want_p = g2h_untagged(start); |
| } |
| |
| if (!(flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))) { |
| /* |
| * Adjust the offset to something representable on the host. |
| */ |
| host_len = len + offset - host_offset; |
| p = mmap(want_p, host_len, host_prot, flags, fd, host_offset); |
| if (p == MAP_FAILED) { |
| return -1; |
| } |
| |
| /* Update start to the file position at offset. */ |
| p += offset - host_offset; |
| |
| start = h2g(p); |
| last = start + len - 1; |
| return mmap_end(start, last, start, last, flags, page_flags); |
| } |
| |
| if (!(flags & MAP_ANONYMOUS)) { |
| misaligned_offset = (start ^ offset) & (host_page_size - 1); |
| |
| /* |
| * The fallback for misalignment is a private mapping + read. |
| * This carries none of semantics required of MAP_SHARED. |
| */ |
| if (misaligned_offset && (flags & MAP_TYPE) != MAP_PRIVATE) { |
| errno = EINVAL; |
| return -1; |
| } |
| } |
| |
| last = start + len - 1; |
| real_start = start & -host_page_size; |
| real_last = ROUND_UP(last, host_page_size) - 1; |
| |
| /* |
| * Handle the start and end of the mapping. |
| */ |
| if (real_start < start) { |
| abi_ulong real_page_last = real_start + host_page_size - 1; |
| if (last <= real_page_last) { |
| /* Entire allocation a subset of one host page. */ |
| if (!mmap_frag(real_start, start, last, target_prot, |
| flags, fd, offset)) { |
| return -1; |
| } |
| return mmap_end(start, last, -1, 0, flags, page_flags); |
| } |
| |
| if (!mmap_frag(real_start, start, real_page_last, target_prot, |
| flags, fd, offset)) { |
| return -1; |
| } |
| real_start = real_page_last + 1; |
| } |
| |
| if (last < real_last) { |
| abi_ulong real_page_start = real_last - host_page_size + 1; |
| if (!mmap_frag(real_page_start, real_page_start, last, |
| target_prot, flags, fd, |
| offset + real_page_start - start)) { |
| return -1; |
| } |
| real_last = real_page_start - 1; |
| } |
| |
| if (real_start > real_last) { |
| return mmap_end(start, last, -1, 0, flags, page_flags); |
| } |
| |
| /* |
| * Handle the middle of the mapping. |
| */ |
| |
| host_len = real_last - real_start + 1; |
| want_p += real_start - start; |
| |
| if (flags & MAP_ANONYMOUS) { |
| p = mmap(want_p, host_len, host_prot, flags, -1, 0); |
| } else if (!misaligned_offset) { |
| p = mmap(want_p, host_len, host_prot, flags, fd, |
| offset + real_start - start); |
| } else { |
| p = mmap(want_p, host_len, host_prot | PROT_WRITE, |
| flags | MAP_ANONYMOUS, -1, 0); |
| } |
| if (p != want_p) { |
| if (p != MAP_FAILED) { |
| do_munmap(p, host_len); |
| errno = EEXIST; |
| } |
| return -1; |
| } |
| |
| if (misaligned_offset) { |
| /* TODO: The read could be short. */ |
| if (pread(fd, p, host_len, offset + real_start - start) != host_len) { |
| do_munmap(p, host_len); |
| return -1; |
| } |
| if (!(host_prot & PROT_WRITE)) { |
| mprotect(p, host_len, host_prot); |
| } |
| } |
| |
| return mmap_end(start, last, -1, 0, flags, page_flags); |
| } |
| |
| static abi_long target_mmap__locked(abi_ulong start, abi_ulong len, |
| int target_prot, int flags, int page_flags, |
| int fd, off_t offset) |
| { |
| int host_page_size = qemu_real_host_page_size(); |
| int host_prot; |
| |
| /* |
| * For reserved_va, we are in full control of the allocation. |
| * Find a suitable hole and convert to MAP_FIXED. |
| */ |
| if (reserved_va) { |
| if (flags & MAP_FIXED_NOREPLACE) { |
| /* Validate that the chosen range is empty. */ |
| if (!page_check_range_empty(start, start + len - 1)) { |
| errno = EEXIST; |
| return -1; |
| } |
| flags = (flags & ~MAP_FIXED_NOREPLACE) | MAP_FIXED; |
| } else if (!(flags & MAP_FIXED)) { |
| abi_ulong real_start = start & -host_page_size; |
| off_t host_offset = offset & -host_page_size; |
| size_t real_len = len + offset - host_offset; |
| abi_ulong align = MAX(host_page_size, TARGET_PAGE_SIZE); |
| |
| start = mmap_find_vma(real_start, real_len, align); |
| if (start == (abi_ulong)-1) { |
| errno = ENOMEM; |
| return -1; |
| } |
| start += offset - host_offset; |
| flags |= MAP_FIXED; |
| } |
| } |
| |
| host_prot = target_to_host_prot(target_prot); |
| |
| if (host_page_size == TARGET_PAGE_SIZE) { |
| return mmap_h_eq_g(start, len, host_prot, flags, |
| page_flags, fd, offset); |
| } else if (host_page_size < TARGET_PAGE_SIZE) { |
| return mmap_h_lt_g(start, len, host_prot, flags, |
| page_flags, fd, offset, host_page_size); |
| } else { |
| return mmap_h_gt_g(start, len, target_prot, host_prot, flags, |
| page_flags, fd, offset, host_page_size); |
| } |
| } |
| |
| /* 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_long ret; |
| int page_flags; |
| |
| trace_target_mmap(start, len, target_prot, flags, fd, offset); |
| |
| if (!len) { |
| errno = EINVAL; |
| return -1; |
| } |
| |
| page_flags = validate_prot_to_pageflags(target_prot); |
| if (!page_flags) { |
| errno = EINVAL; |
| return -1; |
| } |
| |
| /* Also check for overflows... */ |
| len = TARGET_PAGE_ALIGN(len); |
| if (!len || len != (size_t)len) { |
| errno = ENOMEM; |
| return -1; |
| } |
| |
| if (offset & ~TARGET_PAGE_MASK) { |
| errno = EINVAL; |
| return -1; |
| } |
| if (flags & (MAP_FIXED | MAP_FIXED_NOREPLACE)) { |
| if (start & ~TARGET_PAGE_MASK) { |
| errno = EINVAL; |
| return -1; |
| } |
| if (!guest_range_valid_untagged(start, len)) { |
| errno = ENOMEM; |
| return -1; |
| } |
| } |
| |
| mmap_lock(); |
| |
| ret = target_mmap__locked(start, len, target_prot, flags, |
| page_flags, fd, offset); |
| |
| mmap_unlock(); |
| |
| /* |
| * 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 (ret != -1 && (flags & MAP_TYPE) != MAP_PRIVATE) { |
| CPUState *cpu = thread_cpu; |
| if (!tcg_cflags_has(cpu, CF_PARALLEL)) { |
| tcg_cflags_set(cpu, CF_PARALLEL); |
| tb_flush(cpu); |
| } |
| } |
| |
| return ret; |
| } |
| |
| static int mmap_reserve_or_unmap(abi_ulong start, abi_ulong len) |
| { |
| int host_page_size = qemu_real_host_page_size(); |
| 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 & -host_page_size; |
| real_last = ROUND_UP(last, host_page_size) - 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 < 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 0; |
| } |
| } else { |
| for (prot = 0, a = real_start; a < start; a += TARGET_PAGE_SIZE) { |
| prot |= page_get_flags(a); |
| } |
| if (prot != 0) { |
| real_start += 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 -= host_page_size; |
| } |
| |
| if (real_last < real_start) { |
| return 0; |
| } |
| } |
| |
| real_len = real_last - real_start + 1; |
| host_start = g2h_untagged(real_start); |
| |
| return do_munmap(host_start, real_len); |
| } |
| |
| int target_munmap(abi_ulong start, abi_ulong len) |
| { |
| int ret; |
| |
| trace_target_munmap(start, len); |
| |
| if (start & ~TARGET_PAGE_MASK) { |
| errno = EINVAL; |
| return -1; |
| } |
| len = TARGET_PAGE_ALIGN(len); |
| if (len == 0 || !guest_range_valid_untagged(start, len)) { |
| errno = EINVAL; |
| return -1; |
| } |
| |
| mmap_lock(); |
| ret = mmap_reserve_or_unmap(start, len); |
| if (likely(ret == 0)) { |
| page_set_flags(start, start + len - 1, 0); |
| shm_region_rm_complete(start, start + len - 1); |
| } |
| 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; |
| |
| 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 page_flags = 0; |
| if (reserved_va && old_size < new_size) { |
| abi_ulong addr; |
| for (addr = old_addr + old_size; |
| addr < old_addr + new_size; |
| addr++) { |
| page_flags |= page_get_flags(addr); |
| } |
| } |
| if (page_flags == 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); |
| shm_region_rm_complete(old_addr, old_addr + old_size - 1); |
| page_set_flags(new_addr, new_addr + new_size - 1, |
| prot | PAGE_VALID | PAGE_RESET); |
| shm_region_rm_complete(new_addr, new_addr + new_size - 1); |
| } |
| 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; |
| } |
| |
| #ifndef TARGET_FORCE_SHMLBA |
| /* |
| * For most architectures, SHMLBA is the same as the page size; |
| * some architectures have larger values, in which case they should |
| * define TARGET_FORCE_SHMLBA and provide a target_shmlba() function. |
| * This corresponds to the kernel arch code defining __ARCH_FORCE_SHMLBA |
| * and defining its own value for SHMLBA. |
| * |
| * The kernel also permits SHMLBA to be set by the architecture to a |
| * value larger than the page size without setting __ARCH_FORCE_SHMLBA; |
| * this means that addresses are rounded to the large size if |
| * SHM_RND is set but addresses not aligned to that size are not rejected |
| * as long as they are at least page-aligned. Since the only architecture |
| * which uses this is ia64 this code doesn't provide for that oddity. |
| */ |
| static inline abi_ulong target_shmlba(CPUArchState *cpu_env) |
| { |
| return TARGET_PAGE_SIZE; |
| } |
| #endif |
| |
| #if defined(__arm__) || defined(__mips__) || defined(__sparc__) |
| #define HOST_FORCE_SHMLBA 1 |
| #else |
| #define HOST_FORCE_SHMLBA 0 |
| #endif |
| |
| abi_ulong target_shmat(CPUArchState *cpu_env, int shmid, |
| abi_ulong shmaddr, int shmflg) |
| { |
| CPUState *cpu = env_cpu(cpu_env); |
| struct shmid_ds shm_info; |
| int ret; |
| int h_pagesize; |
| int t_shmlba, h_shmlba, m_shmlba; |
| size_t t_len, h_len, m_len; |
| |
| /* shmat pointers are always untagged */ |
| |
| /* |
| * Because we can't use host shmat() unless the address is sufficiently |
| * aligned for the host, we'll need to check both. |
| * TODO: Could be fixed with softmmu. |
| */ |
| t_shmlba = target_shmlba(cpu_env); |
| h_pagesize = qemu_real_host_page_size(); |
| h_shmlba = (HOST_FORCE_SHMLBA ? SHMLBA : h_pagesize); |
| m_shmlba = MAX(t_shmlba, h_shmlba); |
| |
| if (shmaddr) { |
| if (shmaddr & (m_shmlba - 1)) { |
| if (shmflg & SHM_RND) { |
| /* |
| * The guest is allowing the kernel to round the address. |
| * Assume that the guest is ok with us rounding to the |
| * host required alignment too. Anyway if we don't, we'll |
| * get an error from the kernel. |
| */ |
| shmaddr &= ~(m_shmlba - 1); |
| if (shmaddr == 0 && (shmflg & SHM_REMAP)) { |
| return -TARGET_EINVAL; |
| } |
| } else { |
| int require = TARGET_PAGE_SIZE; |
| #ifdef TARGET_FORCE_SHMLBA |
| require = t_shmlba; |
| #endif |
| /* |
| * Include host required alignment, as otherwise we cannot |
| * use host shmat at all. |
| */ |
| require = MAX(require, h_shmlba); |
| if (shmaddr & (require - 1)) { |
| return -TARGET_EINVAL; |
| } |
| } |
| } |
| } else { |
| if (shmflg & SHM_REMAP) { |
| return -TARGET_EINVAL; |
| } |
| } |
| /* All rounding now manually concluded. */ |
| shmflg &= ~SHM_RND; |
| |
| /* Find out the length of the shared memory segment. */ |
| ret = get_errno(shmctl(shmid, IPC_STAT, &shm_info)); |
| if (is_error(ret)) { |
| /* can't get length, bail out */ |
| return ret; |
| } |
| t_len = TARGET_PAGE_ALIGN(shm_info.shm_segsz); |
| h_len = ROUND_UP(shm_info.shm_segsz, h_pagesize); |
| m_len = MAX(t_len, h_len); |
| |
| if (!guest_range_valid_untagged(shmaddr, m_len)) { |
| return -TARGET_EINVAL; |
| } |
| |
| WITH_MMAP_LOCK_GUARD() { |
| bool mapped = false; |
| void *want, *test; |
| abi_ulong last; |
| |
| if (!shmaddr) { |
| shmaddr = mmap_find_vma(0, m_len, m_shmlba); |
| if (shmaddr == -1) { |
| return -TARGET_ENOMEM; |
| } |
| mapped = !reserved_va; |
| } else if (shmflg & SHM_REMAP) { |
| /* |
| * If host page size > target page size, the host shmat may map |
| * more memory than the guest expects. Reject a mapping that |
| * would replace memory in the unexpected gap. |
| * TODO: Could be fixed with softmmu. |
| */ |
| if (t_len < h_len && |
| !page_check_range_empty(shmaddr + t_len, |
| shmaddr + h_len - 1)) { |
| return -TARGET_EINVAL; |
| } |
| } else { |
| if (!page_check_range_empty(shmaddr, shmaddr + m_len - 1)) { |
| return -TARGET_EINVAL; |
| } |
| } |
| |
| /* All placement is now complete. */ |
| want = (void *)g2h_untagged(shmaddr); |
| |
| /* |
| * Map anonymous pages across the entire range, then remap with |
| * the shared memory. This is required for a number of corner |
| * cases for which host and guest page sizes differ. |
| */ |
| if (h_len != t_len) { |
| int mmap_p = PROT_READ | (shmflg & SHM_RDONLY ? 0 : PROT_WRITE); |
| int mmap_f = MAP_PRIVATE | MAP_ANONYMOUS |
| | (reserved_va || mapped || (shmflg & SHM_REMAP) |
| ? MAP_FIXED : MAP_FIXED_NOREPLACE); |
| |
| test = mmap(want, m_len, mmap_p, mmap_f, -1, 0); |
| if (unlikely(test != want)) { |
| /* shmat returns EINVAL not EEXIST like mmap. */ |
| ret = (test == MAP_FAILED && errno != EEXIST |
| ? get_errno(-1) : -TARGET_EINVAL); |
| if (mapped) { |
| do_munmap(want, m_len); |
| } |
| return ret; |
| } |
| mapped = true; |
| } |
| |
| if (reserved_va || mapped) { |
| shmflg |= SHM_REMAP; |
| } |
| test = shmat(shmid, want, shmflg); |
| if (test == MAP_FAILED) { |
| ret = get_errno(-1); |
| if (mapped) { |
| do_munmap(want, m_len); |
| } |
| return ret; |
| } |
| assert(test == want); |
| |
| last = shmaddr + m_len - 1; |
| page_set_flags(shmaddr, last, |
| PAGE_VALID | PAGE_RESET | PAGE_READ | |
| (shmflg & SHM_RDONLY ? 0 : PAGE_WRITE) | |
| (shmflg & SHM_EXEC ? PAGE_EXEC : 0)); |
| |
| shm_region_rm_complete(shmaddr, last); |
| shm_region_add(shmaddr, last); |
| } |
| |
| /* |
| * We're mapping shared memory, so 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 (!tcg_cflags_has(cpu, CF_PARALLEL)) { |
| tcg_cflags_set(cpu, CF_PARALLEL); |
| tb_flush(cpu); |
| } |
| |
| if (qemu_loglevel_mask(CPU_LOG_PAGE)) { |
| FILE *f = qemu_log_trylock(); |
| if (f) { |
| fprintf(f, "page layout changed following shmat\n"); |
| page_dump(f); |
| qemu_log_unlock(f); |
| } |
| } |
| return shmaddr; |
| } |
| |
| abi_long target_shmdt(abi_ulong shmaddr) |
| { |
| abi_long rv; |
| |
| /* shmdt pointers are always untagged */ |
| |
| WITH_MMAP_LOCK_GUARD() { |
| abi_ulong last = shm_region_find(shmaddr); |
| if (last == 0) { |
| return -TARGET_EINVAL; |
| } |
| |
| rv = get_errno(shmdt(g2h_untagged(shmaddr))); |
| if (rv == 0) { |
| abi_ulong size = last - shmaddr + 1; |
| |
| page_set_flags(shmaddr, last, 0); |
| shm_region_rm_complete(shmaddr, last); |
| mmap_reserve_or_unmap(shmaddr, size); |
| } |
| } |
| return rv; |
| } |
