Re: [PATCH v13 04/20] mm, arm64: untag user pointers passed to memory syscalls

Steven Rostedt
2019-03-28T18:19:34Z

On Thu, 28 Mar 2019 19:10:07 +0100
Andrey Konovalov <andreyknvl@google.com> wrote:

> > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > > ---
> > > ipc/shm.c | 2 ++
> > > mm/madvise.c | 2 ++
> > > mm/mempolicy.c | 5 +++++
> > > mm/migrate.c | 1 +
> > > mm/mincore.c | 2 ++
> > > mm/mlock.c | 5 +++++
> > > mm/mmap.c | 7 +++++++
> > > mm/mprotect.c | 1 +
> > > mm/mremap.c | 2 ++
> > > mm/msync.c | 2 ++
> > > 10 files changed, 29 insertions(+)
> >
> > I wonder whether it's better to keep these as wrappers in the arm64
> > code.
>
> I don't think I understand what you propose, could you elaborate?

I believe Catalin is saying that instead of placing things like:

@@ -1593,6 +1593,7 @@ SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
unsigned long ret;
long err;

+ shmaddr = untagged_addr(shmaddr);

To instead have the shmaddr set to the untagged_addr() before calling
the system call, and passing the untagged addr to the system call, as
that goes through the arm64 architecture specific code first.

-- Steve
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