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authorVineet Gupta <vgupta@synopsys.com>2013-01-18 10:42:16 +0100
committerVineet Gupta <vgupta@synopsys.com>2013-02-11 15:30:32 +0100
commit0a5eae458e923af9968679fd75fd1f7670200bc3 (patch)
tree532c2cc732ce69cb15d1746927415a4cc4cc03fa /lib
parentasm-generic: uaccess: Allow arches to over-ride __{get,put}_user_fn() (diff)
downloadlinux-0a5eae458e923af9968679fd75fd1f7670200bc3.tar.xz
linux-0a5eae458e923af9968679fd75fd1f7670200bc3.zip
ARC: [optim] uaccess __{get,put}_user() optimised
Override asm-generic implementations. We basically gain on 2 fronts * checks for alignment no longer needed as we are only doing "unit" sized copies. (Careful observer could argue that While the kernel buffers are aligned, the user buffer in theory might not be - however in that case the user space is already broken when it tries to deref a hword/word straddling word boundary - so we are not making it any worse). * __copy_{to,from}_user( ) returns bytes that couldn't be copied, whereas get_user() returns 0 for success or -EFAULT (not size). Thus the code to do leftover bytes calculation can be avoided as well. The savings were significant: ~17k of code. bloat-o-meter vmlinux_uaccess_pre vmlinux_uaccess_post add/remove: 0/4 grow/shrink: 8/118 up/down: 1262/-18758 (-17496) ^^^^^^^^^ Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
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