On Mon, 2019-03-25 at 15:34 +0100, Arnd Bergmann wrote:
> On big-endian architectures, the signal masks are differnet
> between 32-bit and 64-bit tasks, so we have to use a different
> function for reading them from user space.
>
> io_cqring_wait() initially got this wrong, and always interprets
> this as a native structure. This is ok on x86 and most arm64,
> but not on s390, ppc64be, mips64be, sparc64 and parisc.
>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> fs/io_uring.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 6aaa30580a2b..8f48d29abf76 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -1968,7 +1968,15 @@ static int io_cqring_wait(struct io_ring_ctx
> *ctx, int min_events,
> return 0;
>
> if (sig) {
> - ret = set_user_sigmask(sig, &ksigmask, &sigsaved,
> sigsz);
> +#ifdef CONFIG_COMPAT
> + if (in_compat_syscall())
> + ret = set_compat_user_sigmask((const
> compat_sigset_t __user *)sig,
> + &ksigmask,
> &sigsaved, sigsz);
> + else
> +#endif
This looks a bit suboptimal: shouldn't in_compat_syscall() be hard
coded to return 0 if CONFIG_COMPAT isn't defined? That way the
compiler can do the correct optimization and we don't have to litter
#ifdefs and worry about undefined variables and other things.
James
