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| author | Eric Dumazet <edumazet@google.com> | 2021-04-13 23:33:52 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-04-14 19:04:09 +0300 |
| commit | 5e0ccd4a3b01c5a71732a13186ca110a138516ea (patch) | |
| tree | 83297b8fe4f69131131ac5312aca86e76799568b /kernel/rseq.c | |
| parent | 0ed96051531ecc6965f6456d25b19b9b6bdb5c28 (diff) | |
| download | linux-5e0ccd4a3b01c5a71732a13186ca110a138516ea.tar.xz | |
rseq: Optimise rseq_get_rseq_cs() and clear_rseq_cs()
Commit ec9c82e03a74 ("rseq: uapi: Declare rseq_cs field as union,
update includes") added regressions for our servers.
Using copy_from_user() and clear_user() for 64bit values
is suboptimal.
We can use faster put_user() and get_user() on 64bit arches.
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/20210413203352.71350-4-eric.dumazet@gmail.com
Diffstat (limited to 'kernel/rseq.c')
| -rw-r--r-- | kernel/rseq.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/rseq.c b/kernel/rseq.c index cfe01ab5253c..35f7bd0fced0 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -127,8 +127,13 @@ static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs) u32 sig; int ret; +#ifdef CONFIG_64BIT + if (get_user(ptr, &t->rseq->rseq_cs.ptr64)) + return -EFAULT; +#else if (copy_from_user(&ptr, &t->rseq->rseq_cs.ptr64, sizeof(ptr))) return -EFAULT; +#endif if (!ptr) { memset(rseq_cs, 0, sizeof(*rseq_cs)); return 0; @@ -211,9 +216,13 @@ static int clear_rseq_cs(struct task_struct *t) * * Set rseq_cs to NULL. */ +#ifdef CONFIG_64BIT + return put_user(0UL, &t->rseq->rseq_cs.ptr64); +#else if (clear_user(&t->rseq->rseq_cs.ptr64, sizeof(t->rseq->rseq_cs.ptr64))) return -EFAULT; return 0; +#endif } /* |