From: Eric Dumazet <eduma...@google.com>
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
on 64bit arches is suboptimal.
We might revisit this patch once all 32bit arches support
get_user() and/or put_user() for 8 bytes values.
Signed-off-by: Eric Dumazet <eduma...@google.com>
Cc: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: "Paul E. McKenney" <paul...@kernel.org>
Cc: Boqun Feng <boqun.f...@gmail.com>
Cc: Arjun Roy <arjun...@google.com>
Cc: Ingo Molnar <mi...@kernel.org>
---
kernel/rseq.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/kernel/rseq.c b/kernel/rseq.c
index
57344f9abb43905c7dd2b6081205ff508d963e1e..18a75a804008d2f564d1f7789f09216f1a8760bd
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(0ULL, &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
}
/*
--
2.31.1.295.g9ea45b61b8-goog
