diff options
| -rw-r--r-- | linux-user/elfload.c | 281 |
1 files changed, 100 insertions, 181 deletions
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index a5f9dd5b31..ac03beb01b 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -2683,220 +2683,143 @@ static void pgb_fixed(const char *image_name, uintptr_t guest_loaddr, } /** - * pgd_find_hole_fallback: potential mmap address - * @guest_size: size of available space - * @brk: location of break - * @align: memory alignment + * pgb_find_fallback: * - * This is a fallback method for finding a hole in the host address - * space if we don't have the benefit of being able to access - * /proc/self/map. It can potentially take a very long time as we can - * only dumbly iterate up the host address space seeing if the - * allocation would work. + * This is a fallback method for finding holes in the host address space + * if we don't have the benefit of being able to access /proc/self/map. + * It can potentially take a very long time as we can only dumbly iterate + * up the host address space seeing if the allocation would work. */ -static uintptr_t pgd_find_hole_fallback(uintptr_t guest_size, uintptr_t brk, - long align, uintptr_t offset) +static uintptr_t pgb_find_fallback(const PGBAddrs *ga, uintptr_t align, + uintptr_t brk) { - uintptr_t base; + /* TODO: come up with a better estimate of how much to skip. */ + uintptr_t skip = sizeof(uintptr_t) == 4 ? MiB : GiB; - /* Start (aligned) at the bottom and work our way up */ - base = ROUND_UP(mmap_min_addr, align); - - while (true) { - uintptr_t align_start, end; - align_start = ROUND_UP(base, align); - end = align_start + guest_size + offset; - - /* if brk is anywhere in the range give ourselves some room to grow. */ - if (align_start <= brk && brk < end) { - base = brk + (16 * MiB); - continue; - } else if (align_start + guest_size < align_start) { - /* we have run out of space */ + for (uintptr_t base = skip; ; base += skip) { + base = ROUND_UP(base, align); + if (pgb_try_mmap_set(ga, base, brk)) { + return base; + } + if (base >= -skip) { return -1; - } else { - int flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE | - MAP_FIXED_NOREPLACE; - void * mmap_start = mmap((void *) align_start, guest_size, - PROT_NONE, flags, -1, 0); - if (mmap_start != MAP_FAILED) { - munmap(mmap_start, guest_size); - if (mmap_start == (void *) align_start) { - return (uintptr_t) mmap_start + offset; - } - } - base += qemu_host_page_size; } } } -/* Return value for guest_base, or -1 if no hole found. */ -static uintptr_t pgb_find_hole(uintptr_t guest_loaddr, uintptr_t guest_size, - long align, uintptr_t offset) +static uintptr_t pgb_try_itree(const PGBAddrs *ga, uintptr_t base, + IntervalTreeRoot *root) { - IntervalTreeRoot *maps; - IntervalTreeNode *iter; - uintptr_t this_start, this_end, next_start, brk; - intptr_t ret = -1; - - assert(QEMU_IS_ALIGNED(guest_loaddr, align)); - - maps = read_self_maps(); + for (int i = ga->nbounds - 1; i >= 0; --i) { + uintptr_t s = base + ga->bounds[i][0]; + uintptr_t l = base + ga->bounds[i][1]; + IntervalTreeNode *n; - /* Read brk after we've read the maps, which will malloc. */ - brk = (uintptr_t)sbrk(0); + if (l < s) { + /* Wraparound. Skip to advance S to mmap_min_addr. */ + return mmap_min_addr - s; + } - if (!maps) { - return pgd_find_hole_fallback(guest_size, brk, align, offset); + n = interval_tree_iter_first(root, s, l); + if (n != NULL) { + /* Conflict. Skip to advance S to LAST + 1. */ + return n->last - s + 1; + } } + return 0; /* success */ +} - /* The first hole is before the first map entry. */ - this_start = mmap_min_addr; - - for (iter = interval_tree_iter_first(maps, 0, -1); - iter; - this_start = next_start, - iter = interval_tree_iter_next(iter, 0, -1)) { - MapInfo *info = container_of(iter, MapInfo, itree); - uintptr_t align_start, hole_size; - - this_end = info->itree.start; - next_start = info->itree.last + 1; - align_start = ROUND_UP(this_start + offset, align); +static uintptr_t pgb_find_itree(const PGBAddrs *ga, IntervalTreeRoot *root, + uintptr_t align, uintptr_t brk) +{ + uintptr_t last = mmap_min_addr; + uintptr_t base, skip; - /* Skip holes that are too small. */ - if (align_start >= this_end) { - continue; - } - hole_size = this_end - align_start; - if (hole_size < guest_size) { - continue; + while (true) { + base = ROUND_UP(last, align); + if (base < last) { + return -1; } - /* If this hole contains brk, give ourselves some room to grow. */ - if (this_start <= brk && brk < this_end) { - hole_size -= guest_size; - if (sizeof(uintptr_t) == 8 && hole_size >= 1 * GiB) { - align_start += 1 * GiB; - } else if (hole_size >= 16 * MiB) { - align_start += 16 * MiB; - } else { - align_start = (this_end - guest_size) & -align; - if (align_start < this_start) { - continue; - } - } + skip = pgb_try_itree(ga, base, root); + if (skip == 0) { + break; } - /* Record the lowest successful match. */ - if (ret < 0) { - ret = align_start; - } - /* If this hole contains the identity map, select it. */ - if (align_start <= guest_loaddr && - guest_loaddr + guest_size <= this_end) { - ret = 0; - } - /* If this hole ends above the identity map, stop looking. */ - if (this_end >= guest_loaddr) { - break; + last = base + skip; + if (last < base) { + return -1; } } - free_self_maps(maps); - return ret; + + /* + * We've chosen 'base' based on holes in the interval tree, + * but we don't yet know if it is a valid host address. + * Because it is the first matching hole, if the host addresses + * are invalid we know there are no further matches. + */ + return pgb_try_mmap_set(ga, base, brk) ? base : -1; } -static void pgb_static(const char *image_name, abi_ulong orig_loaddr, - abi_ulong orig_hiaddr, long align) +static void pgb_dynamic(const char *image_name, uintptr_t guest_loaddr, + uintptr_t guest_hiaddr, uintptr_t align) { - uintptr_t loaddr = orig_loaddr; - uintptr_t hiaddr = orig_hiaddr; - uintptr_t offset = 0; - uintptr_t addr; + IntervalTreeRoot *root; + uintptr_t brk, ret; + PGBAddrs ga; - loaddr &= -align; - if (HI_COMMPAGE) { - /* - * Extend the allocation to include the commpage. - * For a 64-bit host, this is just 4GiB; for a 32-bit host we - * need to ensure there is space bellow the guest_base so we - * can map the commpage in the place needed when the address - * arithmetic wraps around. - */ - if (sizeof(uintptr_t) == 8 || loaddr >= 0x80000000u) { - hiaddr = UINT32_MAX; - } else { - offset = -(HI_COMMPAGE & -align); - } - } else if (LO_COMMPAGE != -1) { - loaddr = MIN(loaddr, LO_COMMPAGE & -align); - } + assert(QEMU_IS_ALIGNED(guest_loaddr, align)); - addr = pgb_find_hole(loaddr, hiaddr - loaddr + 1, align, offset); - if (addr == -1) { - /* - * If HI_COMMPAGE, there *might* be a non-consecutive allocation - * that can satisfy both. But as the normal arm32 link base address - * is ~32k, and we extend down to include the commpage, making the - * overhead only ~96k, this is unlikely. - */ - error_report("%s: Unable to allocate %#zx bytes of " - "virtual address space", image_name, - (size_t)(hiaddr - loaddr)); - exit(EXIT_FAILURE); + /* Try the identity map first. */ + if (pgb_addr_set(&ga, guest_loaddr, guest_hiaddr, true)) { + brk = (uintptr_t)sbrk(0); + if (pgb_try_mmap_set(&ga, 0, brk)) { + guest_base = 0; + return; + } } - guest_base = addr; -} - -static void pgb_dynamic(const char *image_name, long align) -{ /* - * The executable is dynamic and does not require a fixed address. - * All we need is a commpage that satisfies align. - * If we do not need a commpage, leave guest_base == 0. + * Rebuild the address set for non-identity map. + * This differs in the mapping of the guest NULL page. */ - if (HI_COMMPAGE) { - uintptr_t addr, commpage; + pgb_addr_set(&ga, guest_loaddr, guest_hiaddr, false); - /* 64-bit hosts should have used reserved_va. */ - assert(sizeof(uintptr_t) == 4); + root = read_self_maps(); + + /* Read brk after we've read the maps, which will malloc. */ + brk = (uintptr_t)sbrk(0); + if (!root) { + ret = pgb_find_fallback(&ga, align, brk); + } else { /* - * By putting the commpage at the first hole, that puts guest_base - * just above that, and maximises the positive guest addresses. + * Reserve the area close to the host brk. + * This will be freed with the rest of the tree. */ - commpage = HI_COMMPAGE & -align; - addr = pgb_find_hole(commpage, -commpage, align, 0); - assert(addr != -1); - guest_base = addr; + IntervalTreeNode *b = g_new0(IntervalTreeNode, 1); + b->start = brk; + b->last = brk + 16 * MiB - 1; + interval_tree_insert(b, root); + + ret = pgb_find_itree(&ga, root, align, brk); + free_self_maps(root); } -} -static void pgb_reserved_va(const char *image_name, abi_ulong guest_loaddr, - abi_ulong guest_hiaddr, long align) -{ - int flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE; - void *addr, *test; - - /* Widen the "image" to the entire reserved address space. */ - pgb_static(image_name, 0, reserved_va, align); - - /* osdep.h defines this as 0 if it's missing */ - flags |= MAP_FIXED_NOREPLACE; - - /* Reserve the memory on the host. */ - assert(guest_base != 0); - test = g2h_untagged(0); - addr = mmap(test, reserved_va + 1, PROT_NONE, flags, -1, 0); - if (addr == MAP_FAILED || addr != test) { - error_report("Unable to reserve 0x%lx bytes of virtual address " - "space at %p (%s) for use as guest address space (check your " - "virtual memory ulimit setting, mmap_min_addr or reserve less " - "using qemu-user's -R option)", - reserved_va + 1, test, strerror(errno)); + if (ret == -1) { + int w = TARGET_LONG_BITS / 4; + + error_report("%s: Unable to find a guest_base to satisfy all " + "guest address mapping requirements", image_name); + + for (int i = 0; i < ga.nbounds; ++i) { + error_printf(" %0*" PRIx64 "-%0*" PRIx64 "\n", + w, (uint64_t)ga.bounds[i][0], + w, (uint64_t)ga.bounds[i][1]); + } exit(EXIT_FAILURE); } + guest_base = ret; } void probe_guest_base(const char *image_name, abi_ulong guest_loaddr, @@ -2924,12 +2847,8 @@ void probe_guest_base(const char *image_name, abi_ulong guest_loaddr, if (have_guest_base) { pgb_fixed(image_name, guest_loaddr, guest_hiaddr, align); - } else if (reserved_va) { - pgb_reserved_va(image_name, guest_loaddr, guest_hiaddr, align); - } else if (guest_loaddr) { - pgb_static(image_name, guest_loaddr, guest_hiaddr, align); } else { - pgb_dynamic(image_name, align); + pgb_dynamic(image_name, guest_loaddr, guest_hiaddr, align); } /* Reserve and initialize the commpage. */ |