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authorEric Dumazet <edumazet@google.com>2021-04-13 23:33:52 +0300
committerPeter Zijlstra <peterz@infradead.org>2021-04-14 19:04:09 +0300
commit5e0ccd4a3b01c5a71732a13186ca110a138516ea (patch)
tree83297b8fe4f69131131ac5312aca86e76799568b /kernel/rseq.c
parent0ed96051531ecc6965f6456d25b19b9b6bdb5c28 (diff)
downloadlinux-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.c9
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
}
/*