Re: [PATCH 14/14] powerpc: remove address space overrides using set_fs()
From: Christophe Leroy <hidden>
Date: 2020-09-03 16:08:41
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linux-arch, linux-fsdevel, lkml
Le 03/09/2020 à 17:56, Christoph Hellwig a écrit :
On Thu, Sep 03, 2020 at 05:49:09PM +0200, Christoph Hellwig wrote:quoted
On Thu, Sep 03, 2020 at 05:43:25PM +0200, Christophe Leroy wrote:quoted
Le 03/09/2020 à 16:22, Christoph Hellwig a écrit :quoted
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@lst.de> ---quoted
-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_MAXTrue. 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.
quoted hunk ↗ jump to hunk
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