/* * 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" #include "bsd-mman.h" #include "exec/exec-all.h" //#define DEBUG_MMAP 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; #ifdef DEBUG_MMAP printf("mprotect: start=0x" TARGET_FMT_lx " len=0x" TARGET_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_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 */ 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 */ void *p = mmap(host_start, qemu_host_page_size, prot, flags | MAP_ANON, -1, 0); if (p == MAP_FAILED) return -1; prot1 = prot; } prot1 &= PAGE_BITS; prot_new = prot | prot1; if (!(flags & MAP_ANON)) { /* 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 */ pread(fd, g2h_untagged(start), end - start, offset); /* 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; } static abi_ulong mmap_next_start = 0x40000000; unsigned long last_brk; /* find a free memory area of size 'size'. The search starts at 'start'. If 'start' == 0, then a default start address is used. Return -1 if error. */ /* page_init() marks pages used by the host as reserved to be sure not to use them. */ static abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) { abi_ulong addr, addr1, addr_start; int prot; unsigned long new_brk; new_brk = (unsigned long)sbrk(0); if (last_brk && last_brk < new_brk && last_brk == (target_ulong)last_brk) { /* This is a hack to catch the host allocating memory with brk(). If it uses mmap then we loose. FIXME: We really want to avoid the host allocating memory in the first place, and maybe leave some slack to avoid switching to mmap. */ page_set_flags(last_brk & TARGET_PAGE_MASK, TARGET_PAGE_ALIGN(new_brk), PAGE_RESERVED); } last_brk = new_brk; size = HOST_PAGE_ALIGN(size); start = start & qemu_host_page_mask; addr = start; if (addr == 0) addr = mmap_next_start; addr_start = addr; for(;;) { prot = 0; for(addr1 = addr; addr1 < (addr + size); addr1 += TARGET_PAGE_SIZE) { prot |= page_get_flags(addr1); } if (prot == 0) break; addr += qemu_host_page_size; /* we found nothing */ if (addr == addr_start) return (abi_ulong)-1; } if (start == 0) mmap_next_start = addr + size; return addr; } /* 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_FMT_lx " len=0x" TARGET_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_ANON) printf("MAP_ANON "); switch(flags & TARGET_BSD_MAP_FLAGMASK) { case MAP_PRIVATE: printf("MAP_PRIVATE "); break; case MAP_SHARED: printf("MAP_SHARED "); break; default: printf("[MAP_FLAGMASK=0x%x] ", flags & TARGET_BSD_MAP_FLAGMASK); break; } printf("fd=%d offset=" TARGET_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; 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_untagged(mmap_start), host_len, prot, flags | MAP_FIXED, fd, host_offset); 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_ANON)) host_start += offset - host_offset; start = h2g(host_start); } else { int flg; target_ulong addr; if (start & ~TARGET_PAGE_MASK) { errno = EINVAL; goto fail; } end = start + len; real_end = HOST_PAGE_ALIGN(end); for(addr = real_start; addr < real_end; addr += TARGET_PAGE_SIZE) { flg = page_get_flags(addr); if (flg & PAGE_RESERVED) { errno = ENXIO; goto fail; } } /* worst case: we cannot map the file because the offset is not aligned, so we read it */ if (!(flags & MAP_ANON) && (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; pread(fd, g2h_untagged(start), len, offset); 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_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_FMT_lx "\n", start); page_dump(stdout); printf("\n"); #endif mmap_unlock(); return start; fail: mmap_unlock(); return -1; } 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%lx len=0x%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) { ret = munmap(g2h_untagged(real_start), real_end - real_start); } if (ret == 0) page_set_flags(start, start + len, 0); 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); }