Rely on target_mmap to handle guest vs host page size mismatch. Tested-by: Helge Deller <del...@gmx.de> Reviewed-by: Helge Deller <del...@gmx.de> Reviewed-by: Akihiko Odaki <akihiko.od...@daynix.com> Signed-off-by: Richard Henderson <richard.hender...@linaro.org> --- linux-user/elfload.c | 54 +++++++++++++++++++------------------------- 1 file changed, 23 insertions(+), 31 deletions(-)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index e853a4ab33..66ab617bd1 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -2212,44 +2212,36 @@ static abi_ulong setup_arg_pages(struct linux_binprm *bprm, /* Map and zero the bss. We need to explicitly zero any fractional pages after the data section (i.e. bss). */ -static void zero_bss(abi_ulong elf_bss, abi_ulong last_bss, int prot) +static void zero_bss(abi_ulong start_bss, abi_ulong end_bss, int prot) { - uintptr_t host_start, host_map_start, host_end; + abi_ulong align_bss; - last_bss = TARGET_PAGE_ALIGN(last_bss); + align_bss = TARGET_PAGE_ALIGN(start_bss); + end_bss = TARGET_PAGE_ALIGN(end_bss); - /* ??? There is confusion between qemu_real_host_page_size and - qemu_host_page_size here and elsewhere in target_mmap, which - may lead to the end of the data section mapping from the file - not being mapped. At least there was an explicit test and - comment for that here, suggesting that "the file size must - be known". The comment probably pre-dates the introduction - of the fstat system call in target_mmap which does in fact - find out the size. What isn't clear is if the workaround - here is still actually needed. For now, continue with it, - but merge it with the "normal" mmap that would allocate the bss. */ + if (start_bss < align_bss) { + int flags = page_get_flags(start_bss); - host_start = (uintptr_t) g2h_untagged(elf_bss); - host_end = (uintptr_t) g2h_untagged(last_bss); - host_map_start = REAL_HOST_PAGE_ALIGN(host_start); - - if (host_map_start < host_end) { - void *p = mmap((void *)host_map_start, host_end - host_map_start, - prot, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); - if (p == MAP_FAILED) { - perror("cannot mmap brk"); - exit(-1); + if (!(flags & PAGE_VALID)) { + /* Map the start of the bss. */ + align_bss -= TARGET_PAGE_SIZE; + } else if (flags & PAGE_WRITE) { + /* The page is already mapped writable. */ + memset(g2h_untagged(start_bss), 0, align_bss - start_bss); + } else { + /* Read-only zeros? */ + g_assert_not_reached(); } } - /* Ensure that the bss page(s) are valid */ - if ((page_get_flags(last_bss-1) & prot) != prot) { - page_set_flags(elf_bss & TARGET_PAGE_MASK, last_bss - 1, - prot | PAGE_VALID); - } - - if (host_start < host_map_start) { - memset((void *)host_start, 0, host_map_start - host_start); + if (align_bss < end_bss) { + abi_long err = target_mmap(align_bss, end_bss - align_bss, prot, + MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, + -1, 0); + if (err == -1) { + perror("cannot mmap brk"); + exit(-1); + } } } -- 2.34.1