diff options
Diffstat (limited to 'linux-user/elfload.c')
| -rw-r--r-- | linux-user/elfload.c | 161 |
1 files changed, 123 insertions, 38 deletions
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 6b622d4ff9..819fdd515a 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -332,9 +332,17 @@ enum ARM_HWCAP_ARM_VFPv3D16 = 1 << 13, }; -#define TARGET_HAS_GUEST_VALIDATE_BASE -/* We want the opportunity to check the suggested base */ -bool guest_validate_base(unsigned long guest_base) +#define TARGET_HAS_VALIDATE_GUEST_SPACE +/* Return 1 if the proposed guest space is suitable for the guest. + * Return 0 if the proposed guest space isn't suitable, but another + * address space should be tried. + * Return -1 if there is no way the proposed guest space can be + * valid regardless of the base. + * The guest code may leave a page mapped and populate it if the + * address is suitable. + */ +static int validate_guest_space(unsigned long guest_base, + unsigned long guest_size) { unsigned long real_start, test_page_addr; @@ -342,6 +350,15 @@ bool guest_validate_base(unsigned long guest_base) * commpage at 0xffff0fxx */ test_page_addr = guest_base + (0xffff0f00 & qemu_host_page_mask); + + /* If the commpage lies within the already allocated guest space, + * then there is no way we can allocate it. + */ + if (test_page_addr >= guest_base + && test_page_addr <= (guest_base + guest_size)) { + return -1; + } + /* Note it needs to be writeable to let us initialise it */ real_start = (unsigned long) mmap((void *)test_page_addr, qemu_host_page_size, @@ -1418,14 +1435,105 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc, return sp; } -#ifndef TARGET_HAS_GUEST_VALIDATE_BASE +#ifndef TARGET_HAS_VALIDATE_GUEST_SPACE /* If the guest doesn't have a validation function just agree */ -bool guest_validate_base(unsigned long guest_base) +static int validate_guest_space(unsigned long guest_base, + unsigned long guest_size) { return 1; } #endif +unsigned long init_guest_space(unsigned long host_start, + unsigned long host_size, + unsigned long guest_start, + bool fixed) +{ + unsigned long current_start, real_start; + int flags; + + assert(host_start || host_size); + + /* If just a starting address is given, then just verify that + * address. */ + if (host_start && !host_size) { + if (validate_guest_space(host_start, host_size) == 1) { + return host_start; + } else { + return (unsigned long)-1; + } + } + + /* Setup the initial flags and start address. */ + current_start = host_start & qemu_host_page_mask; + flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE; + if (fixed) { + flags |= MAP_FIXED; + } + + /* Otherwise, a non-zero size region of memory needs to be mapped + * and validated. */ + while (1) { + unsigned long real_size = host_size; + + /* Do not use mmap_find_vma here because that is limited to the + * guest address space. We are going to make the + * guest address space fit whatever we're given. + */ + real_start = (unsigned long) + mmap((void *)current_start, host_size, PROT_NONE, flags, -1, 0); + if (real_start == (unsigned long)-1) { + return (unsigned long)-1; + } + + /* Ensure the address is properly aligned. */ + if (real_start & ~qemu_host_page_mask) { + munmap((void *)real_start, host_size); + real_size = host_size + qemu_host_page_size; + real_start = (unsigned long) + mmap((void *)real_start, real_size, PROT_NONE, flags, -1, 0); + if (real_start == (unsigned long)-1) { + return (unsigned long)-1; + } + real_start = HOST_PAGE_ALIGN(real_start); + } + + /* Check to see if the address is valid. */ + if (!host_start || real_start == current_start) { + int valid = validate_guest_space(real_start - guest_start, + real_size); + if (valid == 1) { + break; + } else if (valid == -1) { + return (unsigned long)-1; + } + /* valid == 0, so try again. */ + } + + /* That address didn't work. Unmap and try a different one. + * The address the host picked because is typically right at + * the top of the host address space and leaves the guest with + * no usable address space. Resort to a linear search. We + * already compensated for mmap_min_addr, so this should not + * happen often. Probably means we got unlucky and host + * address space randomization put a shared library somewhere + * inconvenient. + */ + munmap((void *)real_start, host_size); + current_start += qemu_host_page_size; + if (host_start == current_start) { + /* Theoretically possible if host doesn't have any suitably + * aligned areas. Normally the first mmap will fail. + */ + return (unsigned long)-1; + } + } + + qemu_log("Reserved 0x%lx bytes of guest address space\n", host_size); + + return real_start; +} + static void probe_guest_base(const char *image_name, abi_ulong loaddr, abi_ulong hiaddr) { @@ -1452,46 +1560,23 @@ static void probe_guest_base(const char *image_name, } } host_size = hiaddr - loaddr; - while (1) { - /* Do not use mmap_find_vma here because that is limited to the - guest address space. We are going to make the - guest address space fit whatever we're given. */ - real_start = (unsigned long) - mmap((void *)host_start, host_size, PROT_NONE, - MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE, -1, 0); - if (real_start == (unsigned long)-1) { - goto exit_perror; - } - guest_base = real_start - loaddr; - if ((real_start == host_start) && - guest_validate_base(guest_base)) { - break; - } - /* That address didn't work. Unmap and try a different one. - The address the host picked because is typically right at - the top of the host address space and leaves the guest with - no usable address space. Resort to a linear search. We - already compensated for mmap_min_addr, so this should not - happen often. Probably means we got unlucky and host - address space randomization put a shared library somewhere - inconvenient. */ - munmap((void *)real_start, host_size); - host_start += qemu_host_page_size; - if (host_start == loaddr) { - /* Theoretically possible if host doesn't have any suitably - aligned areas. Normally the first mmap will fail. */ - errmsg = "Unable to find space for application"; - goto exit_errmsg; - } + + /* Setup the initial guest memory space with ranges gleaned from + * the ELF image that is being loaded. + */ + real_start = init_guest_space(host_start, host_size, loaddr, false); + if (real_start == (unsigned long)-1) { + errmsg = "Unable to find space for application"; + goto exit_errmsg; } + guest_base = real_start - loaddr; + qemu_log("Relocating guest address space from 0x" TARGET_ABI_FMT_lx " to 0x%lx\n", loaddr, real_start); } return; -exit_perror: - errmsg = strerror(errno); exit_errmsg: fprintf(stderr, "%s: %s\n", image_name, errmsg); exit(-1); |