diff options
| -rw-r--r-- | linux-user/elfload.c | 73 |
1 files changed, 67 insertions, 6 deletions
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 13f63cf..4ef77bc 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1666,19 +1666,80 @@ int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * regs, */ if (!have_guest_base) { /* - * Go through ELF program header table and find out whether - * any of the segments drop below our current mmap_min_addr and - * in that case set guest_base to corresponding address. - */ + * Go through ELF program header table and find the address + * range used by loadable segments. Check that this is available on + * the host, and if not find a suitable value for guest_base. */ + abi_ulong app_start = ~0; + abi_ulong app_end = 0; + abi_ulong addr; + unsigned long host_start; + unsigned long real_start; + unsigned long host_size; for (i = 0, elf_ppnt = elf_phdata; i < elf_ex.e_phnum; i++, elf_ppnt++) { if (elf_ppnt->p_type != PT_LOAD) continue; - if (HOST_PAGE_ALIGN(elf_ppnt->p_vaddr) < mmap_min_addr) { - guest_base = HOST_PAGE_ALIGN(mmap_min_addr); + addr = elf_ppnt->p_vaddr; + if (addr < app_start) { + app_start = addr; + } + addr += elf_ppnt->p_memsz; + if (addr > app_end) { + app_end = addr; + } + } + + /* If we don't have any loadable segments then something + is very wrong. */ + assert(app_start < app_end); + + /* Round addresses to page boundaries. */ + app_start = app_start & qemu_host_page_mask; + app_end = HOST_PAGE_ALIGN(app_end); + if (app_start < mmap_min_addr) { + host_start = HOST_PAGE_ALIGN(mmap_min_addr); + } else { + host_start = app_start; + if (host_start != app_start) { + fprintf(stderr, "qemu: Address overflow loading ELF binary\n"); + abort(); + } + } + host_size = app_end - app_start; + 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) { + fprintf(stderr, "qemu: Virtual memory exausted\n"); + abort(); + } + if (real_start == host_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); + host_start += qemu_host_page_size; + if (host_start == app_start) { + /* Theoretically possible if host doesn't have any + suitably aligned areas. Normally the first mmap will + fail. */ + fprintf(stderr, "qemu: Unable to find space for application\n"); + abort(); + } } + qemu_log("Relocating guest address space from 0x" TARGET_ABI_FMT_lx + " to 0x%lx\n", app_start, real_start); + guest_base = real_start - app_start; } #endif /* CONFIG_USE_GUEST_BASE */ |
