summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--fs/exec.c1
-rw-r--r--include/linux/mm_types.h3
-rw-r--r--include/linux/sched/mm.h16
-rw-r--r--include/uapi/linux/membarrier.h23
-rw-r--r--kernel/sched/membarrier.c34
5 files changed, 66 insertions, 11 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 5470d3c1892a..3e14ba25f678 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1802,6 +1802,7 @@ static int do_execveat_common(int fd, struct filename *filename,
/* execve succeeded */
current->fs->in_exec = 0;
current->in_execve = 0;
+ membarrier_execve(current);
acct_update_integrals(current);
task_numa_free(current);
free_bprm(bprm);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 46f4ecf5479a..1861ea8dba77 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -445,6 +445,9 @@ struct mm_struct {
unsigned long flags; /* Must use atomic bitops to access the bits */
struct core_state *core_state; /* coredumping support */
+#ifdef CONFIG_MEMBARRIER
+ atomic_t membarrier_state;
+#endif
#ifdef CONFIG_AIO
spinlock_t ioctx_lock;
struct kioctx_table __rcu *ioctx_table;
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index ae53e413fb13..ab9bf7b73954 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -211,4 +211,20 @@ static inline void memalloc_noreclaim_restore(unsigned int flags)
current->flags = (current->flags & ~PF_MEMALLOC) | flags;
}
+#ifdef CONFIG_MEMBARRIER
+enum {
+ MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0),
+ MEMBARRIER_STATE_SWITCH_MM = (1U << 1),
+};
+
+static inline void membarrier_execve(struct task_struct *t)
+{
+ atomic_set(&t->mm->membarrier_state, 0);
+}
+#else
+static inline void membarrier_execve(struct task_struct *t)
+{
+}
+#endif
+
#endif /* _LINUX_SCHED_MM_H */
diff --git a/include/uapi/linux/membarrier.h b/include/uapi/linux/membarrier.h
index 6d47b3249d8a..4e01ad7ffe98 100644
--- a/include/uapi/linux/membarrier.h
+++ b/include/uapi/linux/membarrier.h
@@ -52,21 +52,30 @@
* (non-running threads are de facto in such a
* state). This only covers threads from the
* same processes as the caller thread. This
- * command returns 0. The "expedited" commands
- * complete faster than the non-expedited ones,
- * they never block, but have the downside of
- * causing extra overhead.
+ * command returns 0 on success. The
+ * "expedited" commands complete faster than
+ * the non-expedited ones, they never block,
+ * but have the downside of causing extra
+ * overhead. A process needs to register its
+ * intent to use the private expedited command
+ * prior to using it, otherwise this command
+ * returns -EPERM.
+ * @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED:
+ * Register the process intent to use
+ * MEMBARRIER_CMD_PRIVATE_EXPEDITED. Always
+ * returns 0.
*
* Command to be passed to the membarrier system call. The commands need to
* be a single bit each, except for MEMBARRIER_CMD_QUERY which is assigned to
* the value 0.
*/
enum membarrier_cmd {
- MEMBARRIER_CMD_QUERY = 0,
- MEMBARRIER_CMD_SHARED = (1 << 0),
+ MEMBARRIER_CMD_QUERY = 0,
+ MEMBARRIER_CMD_SHARED = (1 << 0),
/* reserved for MEMBARRIER_CMD_SHARED_EXPEDITED (1 << 1) */
/* reserved for MEMBARRIER_CMD_PRIVATE (1 << 2) */
- MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3),
+ MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3),
+ MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4),
};
#endif /* _UAPI_LINUX_MEMBARRIER_H */
diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
index a92fddc22747..dd7908743dab 100644
--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -18,6 +18,7 @@
#include <linux/membarrier.h>
#include <linux/tick.h>
#include <linux/cpumask.h>
+#include <linux/atomic.h>
#include "sched.h" /* for cpu_rq(). */
@@ -26,21 +27,26 @@
* except MEMBARRIER_CMD_QUERY.
*/
#define MEMBARRIER_CMD_BITMASK \
- (MEMBARRIER_CMD_SHARED | MEMBARRIER_CMD_PRIVATE_EXPEDITED)
+ (MEMBARRIER_CMD_SHARED | MEMBARRIER_CMD_PRIVATE_EXPEDITED \
+ | MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED)
static void ipi_mb(void *info)
{
smp_mb(); /* IPIs should be serializing but paranoid. */
}
-static void membarrier_private_expedited(void)
+static int membarrier_private_expedited(void)
{
int cpu;
bool fallback = false;
cpumask_var_t tmpmask;
+ if (!(atomic_read(&current->mm->membarrier_state)
+ & MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY))
+ return -EPERM;
+
if (num_online_cpus() == 1)
- return;
+ return 0;
/*
* Matches memory barriers around rq->curr modification in
@@ -94,6 +100,24 @@ static void membarrier_private_expedited(void)
* rq->curr modification in scheduler.
*/
smp_mb(); /* exit from system call is not a mb */
+ return 0;
+}
+
+static void membarrier_register_private_expedited(void)
+{
+ struct task_struct *p = current;
+ struct mm_struct *mm = p->mm;
+
+ /*
+ * We need to consider threads belonging to different thread
+ * groups, which use the same mm. (CLONE_VM but not
+ * CLONE_THREAD).
+ */
+ if (atomic_read(&mm->membarrier_state)
+ & MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY)
+ return;
+ atomic_or(MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY,
+ &mm->membarrier_state);
}
/**
@@ -144,7 +168,9 @@ SYSCALL_DEFINE2(membarrier, int, cmd, int, flags)
synchronize_sched();
return 0;
case MEMBARRIER_CMD_PRIVATE_EXPEDITED:
- membarrier_private_expedited();
+ return membarrier_private_expedited();
+ case MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED:
+ membarrier_register_private_expedited();
return 0;
default:
return -EINVAL;