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rseq: Optimize rseq_update_cpu_id()
authorEric Dumazet <edumazet@google.com>
Tue, 13 Apr 2021 20:33:50 +0000 (13:33 -0700)
committerPeter Zijlstra <peterz@infradead.org>
Wed, 14 Apr 2021 16:04:09 +0000 (18:04 +0200)
commit60af388d23889636011488c42763876bcdda3eab
tree9fa22b294c260a515a6243a3cc77090b79ec5ec5tree | snapshot
parent4bad58ebc8bc4f20d89cff95417c9b4674769709commit | diff
rseq: Optimize rseq_update_cpu_id()

Two put_user() in rseq_update_cpu_id() are replaced
by a pair of unsafe_put_user() with appropriate surroundings.

This removes one stac/clac pair on x86 in fast path.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lkml.kernel.org/r/20210413203352.71350-2-eric.dumazet@gmail.com
kernel/rseq.c diff | blob | history
Domain: System / Kernel;