In preparation to use __u64 for the rseq_cs pointer field, 32-bit
architectures need to read this 64-bit value located in user-space
addresses.
__get_user is used to read this value, given that its access check has
already been performed with access_ok() on rseq registration.
arm does not implement 8-byte __get_user. Rather than trying to
improve __get_user on ARM, use get_user/put_user across rseq instead.
If those end up showing up in benchmarks, the proper approach would be to
use user_access_begin() / unsafe_get/put_user() / user_access_end()
anyway.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Joel Fernandes <joelaf@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dave Watson <davejwatson@xxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: "H . Peter Anvin" <hpa@xxxxxxxxx>
Cc: Chris Lameter <cl@xxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Andrew Hunter <ahh@xxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Cc: "Paul E . McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Paul Turner <pjt@xxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ben Maurer <bmaurer@xxxxxx>
Cc: linux-api@xxxxxxxxxxxxxxx
CC: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
---
kernel/rseq.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/rseq.c b/kernel/rseq.c
index 16b38c5342f9..2c8463acb50d 100644
--- a/kernel/rseq.c
+++ b/kernel/rseq.c
@@ -85,9 +85,9 @@ static int rseq_update_cpu_id(struct task_struct *t)
{
u32 cpu_id = raw_smp_processor_id();
- if (__put_user(cpu_id, &t->rseq->cpu_id_start))
+ if (put_user(cpu_id, &t->rseq->cpu_id_start))
return -EFAULT;
- if (__put_user(cpu_id, &t->rseq->cpu_id))
+ if (put_user(cpu_id, &t->rseq->cpu_id))
return -EFAULT;
trace_rseq_update(t);
return 0;
@@ -100,14 +100,14 @@ static int rseq_reset_rseq_cpu_id(struct task_struct *t)
/*
* Reset cpu_id_start to its initial state (0).
*/
- if (__put_user(cpu_id_start, &t->rseq->cpu_id_start))
+ if (put_user(cpu_id_start, &t->rseq->cpu_id_start))
return -EFAULT;
/*
* Reset cpu_id to RSEQ_CPU_ID_UNINITIALIZED, so any user coming
* in after unregistration can figure out that rseq needs to be
* registered again.
*/
- if (__put_user(cpu_id, &t->rseq->cpu_id))
+ if (put_user(cpu_id, &t->rseq->cpu_id))
return -EFAULT;
return 0;
}
@@ -120,7 +120,7 @@ static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs)
u32 sig;
int ret;
- ret = __get_user(ptr, &t->rseq->rseq_cs);
+ ret = get_user(ptr, &t->rseq->rseq_cs);
if (ret)
return ret;
if (!ptr) {
@@ -163,7 +163,7 @@ static int rseq_need_restart(struct task_struct *t, u32 cs_flags)
int ret;
/* Get thread flags. */
- ret = __get_user(flags, &t->rseq->flags);
+ ret = get_user(flags, &t->rseq->flags);
if (ret)
return ret;
@@ -203,7 +203,7 @@ static int clear_rseq_cs(struct task_struct *t)
*
* Set rseq_cs to NULL with single-copy atomicity.
*/
- return __put_user(0UL, &t->rseq->rseq_cs);
+ return put_user(0UL, &t->rseq->rseq_cs);
}
/*
--
2.11.0
--
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