diff options
| -rw-r--r-- | linux-user/elfload.c | 110 | ||||
| -rw-r--r-- | linux-user/qemu.h | 13 |
2 files changed, 90 insertions, 33 deletions
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 6b622d4ff9..cbc7617765 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1426,6 +1426,73 @@ bool guest_validate_base(unsigned long guest_base) } #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 (guest_validate_base(host_start)) { + 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) { + /* 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; + } + + if ((real_start == current_start) + && guest_validate_base(real_start - guest_start)) { + 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); + 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; + } + } + + return real_start; +} + static void probe_guest_base(const char *image_name, abi_ulong loaddr, abi_ulong hiaddr) { @@ -1452,46 +1519,23 @@ 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); diff --git a/linux-user/qemu.h b/linux-user/qemu.h index 7b299b7bc3..7d4e23e4c1 100644 --- a/linux-user/qemu.h +++ b/linux-user/qemu.h @@ -210,6 +210,19 @@ void fork_end(int child); */ bool guest_validate_base(unsigned long guest_base); +/* Creates the initial guest address space in the host memory space using + * the given host start address hint and size. The guest_start parameter + * specifies the start address of the guest space. guest_base will be the + * difference between the host start address computed by this function and + * guest_start. If fixed is specified, then the mapped address space must + * start at host_start. The real start address of the mapped memory space is + * returned or -1 if there was an error. + */ +unsigned long init_guest_space(unsigned long host_start, + unsigned long host_size, + unsigned long guest_start, + bool fixed); + #include "qemu-log.h" /* strace.c */ |