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authorUwe Kleine-König <u.kleine-koenig@pengutronix.de>2014-06-05 08:23:10 (GMT)
committerUwe Kleine-König <u.kleine-koenig@pengutronix.de>2014-07-01 09:12:09 (GMT)
commit83de911cf897a4317147dd9cb379378c2c4abf4c (patch)
tree0bb9d0b05dce7d740a4d98885a8b44c316e1c5d5 /arch/arm/include
parent03eca200064381d05a54126a711203d443508d80 (diff)
downloadlinux-83de911cf897a4317147dd9cb379378c2c4abf4c.tar.xz
ARM: make user_addr_max more robust
With CONFIG_MMU=y get_fs() returns current_thread_info()->addr_limit which is initialized as USER_DS (which in turn is defined to TASK_SIZE) for userspace processes. At least theoretically current_thread_info()->addr_limit is changable by set_fs() to a different limit, so checking for KERNEL_DS is more robust. With !CONFIG_MMU get_fs returns KERNEL_DS. To see what the old variant did you'd have to find out that USER_DS == KERNEL_DS which isn't needed any more with the variant this patch introduces. So it's a bit easier to understand, too. Also if the limit was changed this limit should be returned, not TASK_SIZE. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Diffstat (limited to 'arch/arm/include')
-rw-r--r--arch/arm/include/asm/uaccess.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 75d9579..fd42da4 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -224,7 +224,7 @@ static inline void set_fs(mm_segment_t fs)
#define access_ok(type,addr,size) (__range_ok(addr,size) == 0)
#define user_addr_max() \
- (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
+ (segment_eq(get_fs(), KERNEL_DS) ? ~0UL : get_fs())
/*
* The "__xxx" versions of the user access functions do not verify the