Re: [PATCH] linux-user:Fix align mistake when mmap guest space

[Laurent Vivier <laurent@vivier.eu>]

Le 13/12/2019 à 03:29, Xinyu Li a écrit :
> In init_guest_space, we need to mmap guest space. If the return address
> of first mmap is not aligned with align, which was set to MAX(SHMLBA,
> qemu_host_page_size), we need unmap and a new mmap(space is larger than
> first size). The new size is named real_size, which is aligned_size +
> qemu_host_page_size. alugned_size is the guest space size. And add a
> qemu_host_page_size to avoid memory error when we align real_start
> manually (ROUND_UP(real_start, align)). But when SHMLBA >
> qemu_host_page_size, the added size will smaller than the size to align,
> which can make a mistake(in a mips machine, it appears). So change
> real_size from aligned_size +qemu_host_page_size
> to aligned_size + align will solve it.
> 
> Signed-off-by: Xinyu Li <precinct@mail.ustc.edu.cn>
> ---
>  linux-user/elfload.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index f6693e5760..312ded0779 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -2189,7 +2189,7 @@ unsigned long init_guest_space(unsigned long host_start,
>               * to where we need to put the commpage.
>               */
>              munmap((void *)real_start, host_size);
> -            real_size = aligned_size + qemu_host_page_size;
> +            real_size = aligned_size + align;
>              real_start = (unsigned long)
>                  mmap((void *)real_start, real_size, PROT_NONE, flags, -1, 0);
>              if (real_start == (unsigned long)-1) {
> 

Applied to my linux-user branch.

Thanks,
Laurent