On 19 September 2016 at 01:24, Marc-André Lureau
wrote:
> tests/tcg/mmap test fails with values other than default target page
> size. When creating a map beyond EOF, extra anonymous pages are added up
> to the target page boundary. Currently, this operation is performed only
> when qemu_real_host_page_size < TARGET_PAGE_SIZE, but it should be
> performed if the configured page size (qemu -p) is larger than
> qemu_real_host_page_size too.
What is the purpose of the -p option, does anybody know?
I don't see why you'd want to be able to manually set what QEMU
thinks the host page size is, it seems like it would mostly
only break things.
> (also fixes some style issues to please checkpatch)
>
> Signed-off-by: Marc-André Lureau
> ---
> linux-user/mmap.c | 27 ++-
> 1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> index c4371d9..4bf79b5 100644
> --- a/linux-user/mmap.c
> +++ b/linux-user/mmap.c
> @@ -415,31 +415,32 @@ abi_long target_mmap(abi_ulong start, abi_ulong len,
> int prot,
> }
>
> /* When mapping files into a memory area larger than the file, accesses
> - to pages beyond the file size will cause a SIGBUS.
> + to pages beyond the file size will cause a SIGBUS.
>
> For example, if mmaping a file of 100 bytes on a host with 4K pages
> emulating a target with 8K pages, the target expects to be able to
> access the first 8K. But the host will trap us on any access beyond
> - 4K.
> + 4K.
>
> When emulating a target with a larger page-size than the hosts, we
> may need to truncate file maps at EOF and add extra anonymous pages
> up to the targets page boundary. */
This comment states what this code is trying to do (handle
the case where the target page size is larger than the
host page size)...
> -if ((qemu_real_host_page_size < TARGET_PAGE_SIZE)
> -&& !(flags & MAP_ANONYMOUS)) {
> - struct stat sb;
> +if ((qemu_real_host_page_size < qemu_host_page_size) &&
> +!(flags & MAP_ANONYMOUS)) {
...but this changes the code so it is no longer doing that.
> +struct stat sb;
>
> - if (fstat (fd, &sb) == -1)
> - goto fail;
> +if (fstat(fd, &sb) == -1) {
> +goto fail;
> +}
>
> /* Are we trying to create a map beyond EOF?. */
> - if (offset + len > sb.st_size) {
> - /* If so, truncate the file map at eof aligned with
> - the hosts real pagesize. Additional anonymous maps
> - will be created beyond EOF. */
> - len = REAL_HOST_PAGE_ALIGN(sb.st_size - offset);
> - }
> +if (offset + len > sb.st_size) {
> +/* If so, truncate the file map at eof aligned with
> + the hosts real pagesize. Additional anonymous maps
> + will be created beyond EOF. */
> +len = REAL_HOST_PAGE_ALIGN(sb.st_size - offset);
> +}
> }
>
> if (!(flags & MAP_FIXED)) {
> --
> 2.10.0
thanks
-- PMM
