diff options
Diffstat (limited to 'linux-user')
| -rw-r--r-- | linux-user/elfload.c | 73 | ||||
| -rw-r--r-- | linux-user/qemu.h | 1 |
2 files changed, 57 insertions, 17 deletions
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 511e450078..f3080a1635 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -10,6 +10,7 @@ #include "qemu/path.h" #include "qemu/queue.h" #include "qemu/guest-random.h" +#include "qemu/units.h" #ifdef _ARCH_PPC64 #undef ARCH_DLINFO @@ -2364,24 +2365,51 @@ static void load_elf_image(const char *image_name, int image_fd, } } - load_addr = loaddr; - if (ehdr->e_type == ET_DYN) { - /* The image indicates that it can be loaded anywhere. Find a - location that can hold the memory space required. If the - image is pre-linked, LOADDR will be non-zero. Since we do - not supply MAP_FIXED here we'll use that address if and - only if it remains available. */ - load_addr = target_mmap(loaddr, hiaddr - loaddr, PROT_NONE, - MAP_PRIVATE | MAP_ANON | MAP_NORESERVE, - -1, 0); - if (load_addr == -1) { - goto exit_perror; + if (pinterp_name != NULL) { + /* + * This is the main executable. + * + * Reserve extra space for brk. + * We hold on to this space while placing the interpreter + * and the stack, lest they be placed immediately after + * the data segment and block allocation from the brk. + * + * 16MB is chosen as "large enough" without being so large + * as to allow the result to not fit with a 32-bit guest on + * a 32-bit host. + */ + info->reserve_brk = 16 * MiB; + hiaddr += info->reserve_brk; + + if (ehdr->e_type == ET_EXEC) { + /* + * Make sure that the low address does not conflict with + * MMAP_MIN_ADDR or the QEMU application itself. + */ + probe_guest_base(image_name, loaddr, hiaddr); } - } else if (pinterp_name != NULL) { - /* This is the main executable. Make sure that the low - address does not conflict with MMAP_MIN_ADDR or the - QEMU application itself. */ - probe_guest_base(image_name, loaddr, hiaddr); + } + + /* + * Reserve address space for all of this. + * + * In the case of ET_EXEC, we supply MAP_FIXED so that we get + * exactly the address range that is required. + * + * Otherwise this is ET_DYN, and we are searching for a location + * that can hold the memory space required. If the image is + * pre-linked, LOADDR will be non-zero, and the kernel should + * honor that address if it happens to be free. + * + * In both cases, we will overwrite pages in this range with mappings + * from the executable. + */ + load_addr = target_mmap(loaddr, hiaddr - loaddr, PROT_NONE, + MAP_PRIVATE | MAP_ANON | MAP_NORESERVE | + (ehdr->e_type == ET_EXEC ? MAP_FIXED : 0), + -1, 0); + if (load_addr == -1) { + goto exit_perror; } load_bias = load_addr - loaddr; @@ -2860,6 +2888,17 @@ int load_elf_binary(struct linux_binprm *bprm, struct image_info *info) bprm->core_dump = &elf_core_dump; #endif + /* + * If we reserved extra space for brk, release it now. + * The implementation of do_brk in syscalls.c expects to be able + * to mmap pages in this space. + */ + if (info->reserve_brk) { + abi_ulong start_brk = HOST_PAGE_ALIGN(info->brk); + abi_ulong end_brk = HOST_PAGE_ALIGN(info->brk + info->reserve_brk); + target_munmap(start_brk, end_brk - start_brk); + } + return 0; } diff --git a/linux-user/qemu.h b/linux-user/qemu.h index f6f5fe5fbb..560a68090e 100644 --- a/linux-user/qemu.h +++ b/linux-user/qemu.h @@ -35,6 +35,7 @@ struct image_info { abi_ulong end_data; abi_ulong start_brk; abi_ulong brk; + abi_ulong reserve_brk; abi_ulong start_mmap; abi_ulong start_stack; abi_ulong stack_limit; |