diff options
| author | Russell King <rmk+kernel@armlinux.org.uk> | 2020-07-22 09:50:23 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@armlinux.org.uk> | 2020-07-22 09:50:55 +0100 |
| commit | 2350ebe2c40dfc2a0830e5eab17976d83f594ded (patch) | |
| tree | dc794babcb29943bc107dccc83f57c00dcbfca07 /arch | |
| parent | 6da5238fa384a3f0d5308b3b11e10f178cb7c20c (diff) | |
ARM: uaccess: add further explanation of __range_ok()
Detail the success return condition, and that we rely on KERNEL_DS
being zero for this to operate correctly.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/include/asm/uaccess.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 98c6b91be4a8..b5fdd30252f8 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -78,7 +78,11 @@ static inline void set_fs(mm_segment_t fs) #define segment_eq(a, b) ((a) == (b)) -/* We use 33-bit arithmetic here... */ +/* + * We use 33-bit arithmetic here. Success returns zero, failure returns + * addr_limit. We take advantage that addr_limit will be zero for KERNEL_DS, + * so this will always return success in that case. + */ #define __range_ok(addr, size) ({ \ unsigned long flag, roksum; \ __chk_user_ptr(addr); \ |