linux-kernel - [tip:core/urgent] rseq: Use get_user/put_user rather than __get_user/__put

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Message-ID: <tip-8f28177014925f968baf45fc833c25848faf8c1c@git.kernel.org>
Date:   Tue, 10 Jul 2018 13:22:27 -0700
From:   tip-bot for Mathieu Desnoyers <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     peterz@...radead.org, catalin.marinas@....com, rostedt@...dmis.org,
        luto@...capital.net, mtk.manpages@...il.com,
        linux-kernel@...r.kernel.org, bmaurer@...com, tglx@...utronix.de,
        mingo@...nel.org, joelaf@...gle.com, andi@...stfloor.org,
        pjt@...gle.com, mathieu.desnoyers@...icios.com,
        paulmck@...ux.vnet.ibm.com, boqun.feng@...il.com,
        davejwatson@...com, linux@....linux.org.uk, hpa@...or.com,
        torvalds@...ux-foundation.org, cl@...ux.com,
        akpm@...ux-foundation.org, josh@...htriplett.org,
        will.deacon@....com
Subject: [tip:core/urgent] rseq: Use get_user/put_user rather than
 __get_user/__put_user

Commit-ID:  8f28177014925f968baf45fc833c25848faf8c1c
Gitweb:     https://git.kernel.org/tip/8f28177014925f968baf45fc833c25848faf8c1c
Author:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
AuthorDate: Mon, 9 Jul 2018 15:51:51 -0400
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue, 10 Jul 2018 22:18:52 +0200

rseq: Use get_user/put_user rather than __get_user/__put_user

__get_user()/__put_user() is used to read values for address ranges that
were already checked with access_ok() on rseq registration.

It has been recognized that __get_user/__put_user are optimizing the
wrong thing. Replace them by 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@...icios.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-api@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Dave Watson <davejwatson@...com>
Cc: Paul Turner <pjt@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Russell King <linux@....linux.org.uk>
Cc: "H . Peter Anvin" <hpa@...or.com>
Cc: Andi Kleen <andi@...stfloor.org>
Cc: Chris Lameter <cl@...ux.com>
Cc: Ben Maurer <bmaurer@...com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Josh Triplett <josh@...htriplett.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will.deacon@....com>
Cc: Michael Kerrisk <mtk.manpages@...il.com>
Cc: Joel Fernandes <joelaf@...gle.com>
Cc: linux-arm-kernel@...ts.infradead.org
Link: https://lkml.kernel.org/r/20180709195155.7654-3-mathieu.desnoyers@efficios.com

---
 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);
 }

 /*