diff options
Diffstat (limited to 'linux-user')
| -rw-r--r-- | linux-user/syscall.c | 29 |
1 files changed, 20 insertions, 9 deletions
diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 5cb27c7f9f..b9757306ac 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -735,23 +735,34 @@ abi_long do_brk(abi_ulong new_brk) return target_brk; } - /* We need to allocate more memory after the brk... */ + /* We need to allocate more memory after the brk... Note that + * we don't use MAP_FIXED because that will map over the top of + * any existing mapping (like the one with the host libc or qemu + * itself); instead we treat "mapped but at wrong address" as + * a failure and unmap again. + */ new_alloc_size = HOST_PAGE_ALIGN(new_brk - brk_page + 1); mapped_addr = get_errno(target_mmap(brk_page, new_alloc_size, PROT_READ|PROT_WRITE, - MAP_ANON|MAP_FIXED|MAP_PRIVATE, 0, 0)); + MAP_ANON|MAP_PRIVATE, 0, 0)); + + if (mapped_addr == brk_page) { + target_brk = new_brk; + return target_brk; + } else if (mapped_addr != -1) { + /* Mapped but at wrong address, meaning there wasn't actually + * enough space for this brk. + */ + target_munmap(mapped_addr, new_alloc_size); + mapped_addr = -1; + } #if defined(TARGET_ALPHA) /* We (partially) emulate OSF/1 on Alpha, which requires we return a proper errno, not an unchanged brk value. */ - if (is_error(mapped_addr)) { - return -TARGET_ENOMEM; - } + return -TARGET_ENOMEM; #endif - - if (!is_error(mapped_addr)) { - target_brk = new_brk; - } + /* For everything else, return the previous break. */ return target_brk; } |