diff options
Diffstat (limited to 'qemu/bsd-user/mmap.c')
| -rw-r--r-- | qemu/bsd-user/mmap.c | 499 |
1 files changed, 499 insertions, 0 deletions
diff --git a/qemu/bsd-user/mmap.c b/qemu/bsd-user/mmap.c new file mode 100644 index 000000000..092bf7f89 --- /dev/null +++ b/qemu/bsd-user/mmap.c @@ -0,0 +1,499 @@ +/* + * 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 <stdlib.h> +#include <stdio.h> +#include <stdarg.h> +#include <string.h> +#include <unistd.h> +#include <errno.h> +#include <sys/mman.h> + +#include "qemu.h" +#include "qemu-common.h" +#include "bsd-mman.h" + +//#define DEBUG_MMAP + +#if defined(CONFIG_USE_NPTL) +pthread_mutex_t mmap_mutex; +static int __thread mmap_lock_count; + +void mmap_lock(void) +{ + if (mmap_lock_count++ == 0) { + pthread_mutex_lock(&mmap_mutex); + } +} + +void mmap_unlock(void) +{ + if (--mmap_lock_count == 0) { + pthread_mutex_unlock(&mmap_mutex); + } +} + +/* Grab lock to make sure things are in a consistent state after fork(). */ +void mmap_fork_start(void) +{ + if (mmap_lock_count) + abort(); + pthread_mutex_lock(&mmap_mutex); +} + +void mmap_fork_end(int child) +{ + if (child) + pthread_mutex_init(&mmap_mutex, NULL); + else + pthread_mutex_unlock(&mmap_mutex); +} +#else +/* We aren't threadsafe to start with, so no need to worry about locking. */ +void mmap_lock(void) +{ +} + +void mmap_unlock(void) +{ +} +#endif + +/* NOTE: all the constants are the HOST ones, but addresses are target. */ +int target_mprotect(abi_ulong start, abi_ulong len, int prot) +{ + abi_ulong end, host_start, host_end, addr; + int prot1, ret; + +#ifdef DEBUG_MMAP + printf("mprotect: start=0x" TARGET_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(host_start), qemu_host_page_size, prot1 & PAGE_BITS); + if (ret != 0) + goto error; + host_start += qemu_host_page_size; + } + if (end < host_end) { + prot1 = prot; + for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { + prot1 |= page_get_flags(addr); + } + ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size, + prot1 & PAGE_BITS); + if (ret != 0) + goto error; + host_end -= qemu_host_page_size; + } + + /* handle the pages in the middle */ + if (host_start < host_end) { + ret = mprotect(g2h(host_start), host_end - host_start, prot); + if (ret != 0) + goto error; + } + page_set_flags(start, start + len, prot | PAGE_VALID); + mmap_unlock(); + return 0; +error: + mmap_unlock(); + return ret; +} + +/* map an incomplete host page */ +static int mmap_frag(abi_ulong real_start, + abi_ulong start, abi_ulong end, + int prot, int flags, int fd, abi_ulong offset) +{ + abi_ulong real_end, addr; + void *host_start; + int prot1, prot_new; + + real_end = real_start + qemu_host_page_size; + host_start = g2h(real_start); + + /* get the protection of the target pages outside the mapping */ + prot1 = 0; + for(addr = real_start; addr < real_end; addr++) { + if (addr < start || addr >= end) + prot1 |= page_get_flags(addr); + } + + if (prot1 == 0) { + /* no page was there, so we allocate one */ + void *p = mmap(host_start, qemu_host_page_size, prot, + flags | MAP_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(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; +} + +#if defined(__CYGWIN__) +/* Cygwin doesn't have a whole lot of address space. */ +static abi_ulong mmap_next_start = 0x18000000; +#else +static abi_ulong mmap_next_start = 0x40000000; +#endif + +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(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(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(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(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(start), end - start, flags); +} |