On Thu, Sep 03, 2020 at 05:49:09PM +0200, Christoph Hellwig wrote:
> On Thu, Sep 03, 2020 at 05:43:25PM +0200, Christophe Leroy wrote:
> >
> >
> > Le 03/09/2020 à 16:22, Christoph Hellwig a écrit :
> >> Stop providing the possibility to override the address space using
> >> set_fs() now that there is no need for that any more.
> >>
> >> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> >> ---
> >
> >
> >> -static inline int __access_ok(unsigned long addr, unsigned long size,
> >> - mm_segment_t seg)
> >> +static inline bool __access_ok(unsigned long addr, unsigned long size)
> >> {
> >> - if (addr > seg.seg)
> >> - return 0;
> >> - return (size == 0 || size - 1 <= seg.seg - addr);
> >> + if (addr >= TASK_SIZE_MAX)
> >> + return false;
> >> + return size == 0 || size <= TASK_SIZE_MAX - addr;
> >> }
> >
> > You don't need to test size == 0 anymore. It used to be necessary because
> > of the 'size - 1', as size is unsigned.
> >
> > Now you can directly do
> >
> > return size <= TASK_SIZE_MAX - addr;
> >
> > If size is 0, this will always be true (because you already know that addr
> > is not >= TASK_SIZE_MAX
>
> True. What do you think of Linus' comment about always using the
> ppc32 version on ppc64 as well with this?
i.e. something like this folded in:
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 5363f7fc6dd06c..be070254e50943 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -11,26 +11,14 @@
#ifdef __powerpc64__
/* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
#define TASK_SIZE_MAX TASK_SIZE_USER64
-
-/*
- * This check is sufficient because there is a large enough gap between user
- * addresses and the kernel addresses.
- */
-static inline bool __access_ok(unsigned long addr, unsigned long size)
-{
- return addr < TASK_SIZE_MAX && size < TASK_SIZE_MAX;
-}
-
#else
#define TASK_SIZE_MAX TASK_SIZE
+#endif
static inline bool __access_ok(unsigned long addr, unsigned long size)
{
- if (addr >= TASK_SIZE_MAX)
- return false;
- return size == 0 || size <= TASK_SIZE_MAX - addr;
+ return addr < TASK_SIZE_MAX && size <= TASK_SIZE_MAX - addr;
}
-#endif /* __powerpc64__ */
#define access_ok(addr, size) \
(__chk_user_ptr(addr), \
