Re: [PATCH v15 05/17] arms64: untag user pointers passed to memory syscalls

Catalin Marinas
2019-05-27T14:37:32Z

On Mon, May 06, 2019 at 06:30:51PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
>
> This patch allows tagged pointers to be passed to the following memory
> syscalls: brk, get_mempolicy, madvise, mbind, mincore, mlock, mlock2,
> mmap, mmap_pgoff, mprotect, mremap, msync, munlock, munmap,
> remap_file_pages, shmat and shmdt.
>
> This is done by untagging pointers passed to these syscalls in the
> prologues of their handlers.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Actually, I don't think any of these wrappers get called (have you
tested this patch?). Following commit 4378a7d4be30 ("arm64: implement
syscall wrappers"), I think we have other macro names for overriding the
sys_* ones.

--
Catalin