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authorLinus Torvalds <torvalds@linux-foundation.org>2024-10-29 16:03:31 -1000
committerLinus Torvalds <torvalds@linux-foundation.org>2024-10-30 11:38:10 -1000
commit0fc810ae3ae110f9e2fcccce80fc8c8d62f97907 (patch)
tree983d3b661ca5c20363d7066b01252b6473ee95a3 /scripts/dtc/libfdt
parent14b7d43c5c068cb9688a9fe68883f4340effb053 (diff)
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x86/uaccess: Avoid barrier_nospec() in 64-bit copy_from_user()HEADmaster
The barrier_nospec() in 64-bit copy_from_user() is slow. Instead use pointer masking to force the user pointer to all 1's for an invalid address. The kernel test robot reports a 2.6% improvement in the per_thread_ops benchmark [1]. This is a variation on a patch originally by Josh Poimboeuf [2]. Link: https://lore.kernel.org/202410281344.d02c72a2-oliver.sang@intel.com [1] Link: https://lore.kernel.org/5b887fe4c580214900e21f6c61095adf9a142735.1730166635.git.jpoimboe@kernel.org [2] Tested-and-reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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