[PATCH for 4.18 2/6] rseq: use get_user/put_user rather than __get_user/__put_user
From: mathieu.desnoyers@efficios.com (Mathieu Desnoyers)
Date: 2018-07-08 21:04:03
Also in:
linux-api, lkml
Subsystem:
restartable sequences support, the rest · Maintainers:
Mathieu Desnoyers, Peter Zijlstra, "Paul E. McKenney", Boqun Feng, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2018-07-09 · [PATCH for 4.18 2/6] rseq: use get_user/put_user rather than __get_user/__put_user · Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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@efficios.com> CC: Thomas Gleixner <redacted> Cc: Joel Fernandes <redacted> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Watson <redacted> Cc: Will Deacon <redacted> Cc: Andi Kleen <redacted> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: Chris Lameter <redacted> Cc: Russell King <redacted> Cc: Andrew Hunter <redacted> Cc: Michael Kerrisk <redacted> Cc: "Paul E . McKenney" <redacted> Cc: Paul Turner <redacted> Cc: Boqun Feng <redacted> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ben Maurer <redacted> Cc: linux-api at vger.kernel.org CC: linux-arm-kernel at lists.infradead.org Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> --- 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