Le 03/09/2020 à 17:56, Christoph Hellwig a écrit :
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 have nothing against it. That's only adding a substract, all args are
already in registers so that will be in the noise for a modern CPU.
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), \
Christophe
