diff options
Diffstat (limited to 'bsd-user')
| -rw-r--r-- | bsd-user/main.c | 43 | ||||
| -rw-r--r-- | bsd-user/mmap.c | 415 | ||||
| -rw-r--r-- | bsd-user/qemu.h | 5 |
3 files changed, 392 insertions, 71 deletions
diff --git a/bsd-user/main.c b/bsd-user/main.c index 6df4f4f011..48643eeabc 100644 --- a/bsd-user/main.c +++ b/bsd-user/main.c @@ -52,10 +52,47 @@ #include "target_arch_cpu.h" int singlestep; -unsigned long mmap_min_addr; uintptr_t guest_base; bool have_guest_base; +/* + * When running 32-on-64 we should make sure we can fit all of the possible + * guest address space into a contiguous chunk of virtual host memory. + * + * This way we will never overlap with our own libraries or binaries or stack + * or anything else that QEMU maps. + * + * Many cpus reserve the high bit (or more than one for some 64-bit cpus) + * of the address for the kernel. Some cpus rely on this and user space + * uses the high bit(s) for pointer tagging and the like. For them, we + * must preserve the expected address space. + */ +#ifndef MAX_RESERVED_VA +# if HOST_LONG_BITS > TARGET_VIRT_ADDR_SPACE_BITS +# if TARGET_VIRT_ADDR_SPACE_BITS == 32 && \ + (TARGET_LONG_BITS == 32 || defined(TARGET_ABI32)) +/* + * There are a number of places where we assign reserved_va to a variable + * of type abi_ulong and expect it to fit. Avoid the last page. + */ +# define MAX_RESERVED_VA (0xfffffffful & TARGET_PAGE_MASK) +# else +# define MAX_RESERVED_VA (1ul << TARGET_VIRT_ADDR_SPACE_BITS) +# endif +# else +# define MAX_RESERVED_VA 0 +# endif +#endif + +/* + * That said, reserving *too* much vm space via mmap can run into problems + * with rlimits, oom due to page table creation, etc. We will still try it, + * if directed by the command-line option, but not by default. + */ +#if HOST_LONG_BITS == 64 && TARGET_VIRT_ADDR_SPACE_BITS <= 32 +unsigned long reserved_va = MAX_RESERVED_VA; +#else unsigned long reserved_va; +#endif static const char *interp_prefix = CONFIG_QEMU_INTERP_PREFIX; const char *qemu_uname_release; @@ -439,6 +476,10 @@ int main(int argc, char **argv) target_environ = envlist_to_environ(envlist, NULL); envlist_free(envlist); + if (reserved_va) { + mmap_next_start = reserved_va; + } + { Error *err = NULL; if (seed_optarg != NULL) { diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c index 8918c4ae68..b40ab9045f 100644 --- a/bsd-user/mmap.c +++ b/bsd-user/mmap.c @@ -188,64 +188,207 @@ static int mmap_frag(abi_ulong real_start, return 0; } -static abi_ulong mmap_next_start = 0x40000000; +#if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64 +# define TASK_UNMAPPED_BASE (1ul << 38) +#else +# define TASK_UNMAPPED_BASE 0x40000000 +#endif +abi_ulong mmap_next_start = TASK_UNMAPPED_BASE; unsigned long last_brk; -/* 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) +/* + * Subroutine of mmap_find_vma, used when we have pre-allocated a chunk of guest + * address space. + */ +static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size, + abi_ulong alignment) { - abi_ulong addr, addr1, addr_start; + abi_ulong addr; + abi_ulong end_addr; int prot; - unsigned long new_brk; + int looped = 0; + + if (size > reserved_va) { + return (abi_ulong)-1; + } + + size = HOST_PAGE_ALIGN(size) + alignment; + end_addr = start + size; + if (end_addr > reserved_va) { + end_addr = reserved_va; + } + addr = end_addr - qemu_host_page_size; - 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); + while (1) { + if (addr > end_addr) { + if (looped) { + return (abi_ulong)-1; + } + end_addr = reserved_va; + addr = end_addr - qemu_host_page_size; + looped = 1; + continue; + } + prot = page_get_flags(addr); + if (prot) { + end_addr = addr; + } + if (end_addr - addr >= size) { + break; + } + addr -= qemu_host_page_size; + } + + if (start == mmap_next_start) { + mmap_next_start = addr; + } + /* addr is sufficiently low to align it up */ + if (alignment != 0) { + addr = (addr + alignment) & ~(alignment - 1); + } + return addr; +} + +/* + * Find and reserve a free memory area of size 'size'. The search + * starts at 'start'. + * It must be called with mmap_lock() held. + * Return -1 if error. + */ +static abi_ulong mmap_find_vma_aligned(abi_ulong start, abi_ulong size, + abi_ulong alignment) +{ + void *ptr, *prev; + abi_ulong addr; + int flags; + int wrapped, repeat; + + /* If 'start' == 0, then a default start address is used. */ + if (start == 0) { + start = mmap_next_start; + } else { + start &= qemu_host_page_mask; } - last_brk = new_brk; size = HOST_PAGE_ALIGN(size); - start = start & qemu_host_page_mask; + + if (reserved_va) { + return mmap_find_vma_reserved(start, size, + (alignment != 0 ? 1 << alignment : 0)); + } + 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); + wrapped = repeat = 0; + prev = 0; + flags = MAP_ANONYMOUS | MAP_PRIVATE; +#ifdef MAP_ALIGNED + if (alignment != 0) { + flags |= MAP_ALIGNED(alignment); + } +#else + /* XXX TODO */ +#endif + + for (;; prev = ptr) { + /* + * Reserve needed memory area to avoid a race. + * It should be discarded using: + * - mmap() with MAP_FIXED flag + * - mremap() with MREMAP_FIXED flag + * - shmat() with SHM_REMAP flag + */ + ptr = mmap(g2h_untagged(addr), size, PROT_NONE, + flags, -1, 0); + + /* ENOMEM, if host address space has no memory */ + if (ptr == MAP_FAILED) { + return (abi_ulong)-1; } - if (prot == 0) - break; - addr += qemu_host_page_size; - /* we found nothing */ - if (addr == addr_start) + + /* + * Count the number of sequential returns of the same address. + * This is used to modify the search algorithm below. + */ + repeat = (ptr == prev ? repeat + 1 : 0); + + if (h2g_valid(ptr + size - 1)) { + addr = h2g(ptr); + + if ((addr & ~TARGET_PAGE_MASK) == 0) { + /* Success. */ + if (start == mmap_next_start && addr >= TASK_UNMAPPED_BASE) { + mmap_next_start = addr + size; + } + return addr; + } + + /* The address is not properly aligned for the target. */ + switch (repeat) { + case 0: + /* + * Assume the result that the kernel gave us is the + * first with enough free space, so start again at the + * next higher target page. + */ + addr = TARGET_PAGE_ALIGN(addr); + break; + case 1: + /* + * Sometimes the kernel decides to perform the allocation + * at the top end of memory instead. + */ + addr &= TARGET_PAGE_MASK; + break; + case 2: + /* Start over at low memory. */ + addr = 0; + break; + default: + /* Fail. This unaligned block must the last. */ + addr = -1; + break; + } + } else { + /* + * Since the result the kernel gave didn't fit, start + * again at low memory. If any repetition, fail. + */ + addr = (repeat ? -1 : 0); + } + + /* Unmap and try again. */ + munmap(ptr, size); + + /* ENOMEM if we checked the whole of the target address space. */ + if (addr == (abi_ulong)-1) { + return (abi_ulong)-1; + } else if (addr == 0) { + if (wrapped) { + return (abi_ulong)-1; + } + wrapped = 1; + /* + * Don't actually use 0 when wrapping, instead indicate + * that we'd truly like an allocation in low memory. + */ + addr = TARGET_PAGE_SIZE; + } else if (wrapped && addr >= start) { return (abi_ulong)-1; + } } - if (start == 0) - mmap_next_start = addr + size; - return addr; +} + +abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) +{ + return mmap_find_vma_aligned(start, size, 0); } /* NOTE: all the constants are the HOST ones */ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, - int flags, int fd, abi_ulong offset) + int flags, int fd, off_t offset) { abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len; - unsigned long host_start; mmap_lock(); #ifdef DEBUG_MMAP @@ -294,43 +437,121 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, } #endif + if ((flags & MAP_ANONYMOUS) && fd != -1) { + errno = EINVAL; + goto fail; + } +#ifdef MAP_STACK + if (flags & MAP_STACK) { + if ((fd != -1) || ((prot & (PROT_READ | PROT_WRITE)) != + (PROT_READ | PROT_WRITE))) { + errno = EINVAL; + goto fail; + } + } +#endif /* MAP_STACK */ +#ifdef MAP_GUARD + if ((flags & MAP_GUARD) && (prot != PROT_NONE || fd != -1 || + offset != 0 || (flags & (MAP_SHARED | MAP_PRIVATE | + /* MAP_PREFAULT | */ /* MAP_PREFAULT not in mman.h */ + MAP_PREFAULT_READ | MAP_ANON | MAP_STACK)) != 0)) { + errno = EINVAL; + goto fail; + } +#endif + if (offset & ~TARGET_PAGE_MASK) { errno = EINVAL; goto fail; } len = TARGET_PAGE_ALIGN(len); - if (len == 0) - goto the_end; + if (len == 0) { + errno = EINVAL; + goto fail; + } real_start = start & qemu_host_page_mask; + host_offset = offset & qemu_host_page_mask; + /* + * If the user is asking for the kernel to find a location, do that + * before we truncate the length for mapping files below. + */ if (!(flags & MAP_FIXED)) { - 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) { + if ((flags & MAP_ALIGNMENT_MASK) != 0) + start = mmap_find_vma_aligned(real_start, host_len, + (flags & MAP_ALIGNMENT_MASK) >> MAP_ALIGNMENT_SHIFT); + else + start = mmap_find_vma(real_start, host_len); + if (start == (abi_ulong)-1) { errno = ENOMEM; goto fail; } - /* 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); + } + + /* + * When mapping files into a memory area larger than the file, accesses + * to pages beyond the file size will cause a SIGBUS. + * + * For example, if mmaping a file of 100 bytes on a host with 4K pages + * emulating a target with 8K pages, the target expects to be able to + * access the first 8K. But the host will trap us on any access beyond + * 4K. + * + * When emulating a target with a larger page-size than the hosts, we + * may need to truncate file maps at EOF and add extra anonymous pages + * up to the targets page boundary. + */ + + if ((qemu_real_host_page_size < qemu_host_page_size) && fd != -1) { + struct stat sb; + + if (fstat(fd, &sb) == -1) { + goto fail; + } + + /* Are we trying to create a map beyond EOF?. */ + if (offset + len > sb.st_size) { + /* + * If so, truncate the file map at eof aligned with + * the hosts real pagesize. Additional anonymous maps + * will be created beyond EOF. + */ + len = REAL_HOST_PAGE_ALIGN(sb.st_size - offset); + } + } + + if (!(flags & MAP_FIXED)) { + unsigned long host_start; + void *p; + + host_len = len + offset - host_offset; + host_len = HOST_PAGE_ALIGN(host_len); + + /* + * Note: we prefer to control the mapping address. It is + * especially important if qemu_host_page_size > + * qemu_real_host_page_size + */ + p = mmap(g2h_untagged(start), host_len, prot, + flags | MAP_FIXED | ((fd != -1) ? MAP_ANONYMOUS : 0), -1, 0); if (p == MAP_FAILED) goto fail; /* update start so that it points to the file position at 'offset' */ host_start = (unsigned long)p; - if (!(flags & MAP_ANON)) + if (fd != -1) { + p = mmap(g2h_untagged(start), len, prot, + flags | MAP_FIXED, fd, host_offset); + if (p == MAP_FAILED) { + munmap(g2h_untagged(start), host_len); + goto fail; + } host_start += offset - host_offset; + } start = h2g(host_start); } else { - int flg; - target_ulong addr; - if (start & ~TARGET_PAGE_MASK) { errno = EINVAL; goto fail; @@ -338,20 +559,28 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, 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; - } + /* + * 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 TARGET_ABI_BITS == 32 && HOST_LONG_BITS == 64 + if ((unsigned long)start + len - 1 > (abi_ulong) -1) { + errno = EINVAL; + goto fail; } +#endif - /* worst case: we cannot map the file because the offset is not - aligned, so we read it */ + /* + * 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 */ + /* + * 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; @@ -392,7 +621,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, /* 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, + real_end - qemu_host_page_size, end, prot, flags, fd, offset + real_end - qemu_host_page_size - start); if (ret == -1) @@ -422,6 +651,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, page_dump(stdout); printf("\n"); #endif + tb_invalidate_phys_range(start, start + len); mmap_unlock(); return start; fail: @@ -429,6 +659,49 @@ fail: return -1; } +static void mmap_reserve(abi_ulong start, abi_ulong size) +{ + abi_ulong real_start; + abi_ulong real_end; + abi_ulong addr; + abi_ulong end; + int prot; + + real_start = start & qemu_host_page_mask; + real_end = HOST_PAGE_ALIGN(start + size); + end = start + size; + if (start > real_start) { + /* handle host page containing start */ + prot = 0; + for (addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { + prot |= page_get_flags(addr); + } + if (real_end == real_start + qemu_host_page_size) { + for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { + prot |= page_get_flags(addr); + } + end = real_end; + } + if (prot != 0) { + real_start += qemu_host_page_size; + } + } + if (end < real_end) { + prot = 0; + for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { + prot |= page_get_flags(addr); + } + if (prot != 0) { + real_end -= qemu_host_page_size; + } + } + if (real_start != real_end) { + mmap(g2h_untagged(real_start), real_end - real_start, PROT_NONE, + MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, + -1, 0); + } +} + int target_munmap(abi_ulong start, abi_ulong len) { abi_ulong end, real_start, real_end, addr; @@ -476,11 +749,17 @@ int target_munmap(abi_ulong start, abi_ulong len) ret = 0; /* unmap what we can */ if (real_start < real_end) { - ret = munmap(g2h_untagged(real_start), real_end - real_start); + if (reserved_va) { + mmap_reserve(real_start, real_end - real_start); + } else { + ret = munmap(g2h_untagged(real_start), real_end - real_start); + } } - if (ret == 0) + if (ret == 0) { page_set_flags(start, start + len, 0); + tb_invalidate_phys_range(start, start + len); + } mmap_unlock(); return ret; } diff --git a/bsd-user/qemu.h b/bsd-user/qemu.h index 8d20554688..522d6c4031 100644 --- a/bsd-user/qemu.h +++ b/bsd-user/qemu.h @@ -105,7 +105,6 @@ typedef struct TaskState { void init_task_state(TaskState *ts); extern const char *qemu_uname_release; -extern unsigned long mmap_min_addr; /* * TARGET_ARG_MAX defines the number of bytes allocated for arguments @@ -215,13 +214,15 @@ abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong sp); /* mmap.c */ int target_mprotect(abi_ulong start, abi_ulong len, int prot); abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, - int flags, int fd, abi_ulong offset); + int flags, int fd, off_t offset); int target_munmap(abi_ulong start, abi_ulong len); abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size, abi_ulong new_size, unsigned long flags, abi_ulong new_addr); int target_msync(abi_ulong start, abi_ulong len, int flags); extern unsigned long last_brk; +extern abi_ulong mmap_next_start; +abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size); void mmap_fork_start(void); void mmap_fork_end(int child); |