diff options
Diffstat (limited to 'kernel/sched/membarrier.c')
| -rw-r--r-- | kernel/sched/membarrier.c | 29 |
1 files changed, 21 insertions, 8 deletions
diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index 2ad881d07752..623445603725 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -4,6 +4,8 @@ * * membarrier system call */ +#include <uapi/linux/membarrier.h> +#include "sched.h" /* * For documentation purposes, here are some membarrier ordering @@ -162,6 +164,9 @@ | MEMBARRIER_PRIVATE_EXPEDITED_RSEQ_BITMASK \ | MEMBARRIER_CMD_GET_REGISTRATIONS) +static DEFINE_MUTEX(membarrier_ipi_mutex); +#define SERIALIZE_IPI() guard(mutex)(&membarrier_ipi_mutex) + static void ipi_mb(void *info) { smp_mb(); /* IPIs should be serializing but paranoid. */ @@ -194,7 +199,7 @@ static void ipi_rseq(void *info) * is negligible. */ smp_mb(); - rseq_preempt(current); + rseq_sched_switch_event(current); } static void ipi_sync_rq_state(void *info) @@ -251,7 +256,7 @@ static int membarrier_global_expedited(void) return 0; /* - * Matches memory barriers around rq->curr modification in + * Matches memory barriers after rq->curr modification in * scheduler. */ smp_mb(); /* system call entry is not a mb. */ @@ -259,6 +264,7 @@ static int membarrier_global_expedited(void) if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL)) return -ENOMEM; + SERIALIZE_IPI(); cpus_read_lock(); rcu_read_lock(); for_each_online_cpu(cpu) { @@ -300,7 +306,7 @@ static int membarrier_global_expedited(void) /* * Memory barrier on the caller thread _after_ we finished - * waiting for the last IPI. Matches memory barriers around + * waiting for the last IPI. Matches memory barriers before * rq->curr modification in scheduler. */ smp_mb(); /* exit from system call is not a mb */ @@ -320,6 +326,7 @@ static int membarrier_private_expedited(int flags, int cpu_id) MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY)) return -EPERM; ipi_func = ipi_sync_core; + prepare_sync_core_cmd(mm); } else if (flags == MEMBARRIER_FLAG_RSEQ) { if (!IS_ENABLED(CONFIG_RSEQ)) return -EINVAL; @@ -339,14 +346,19 @@ static int membarrier_private_expedited(int flags, int cpu_id) return 0; /* - * Matches memory barriers around rq->curr modification in + * Matches memory barriers after rq->curr modification in * scheduler. + * + * On RISC-V, this barrier pairing is also needed for the + * SYNC_CORE command when switching between processes, cf. + * the inline comments in membarrier_arch_switch_mm(). */ smp_mb(); /* system call entry is not a mb. */ if (cpu_id < 0 && !zalloc_cpumask_var(&tmpmask, GFP_KERNEL)) return -ENOMEM; + SERIALIZE_IPI(); cpus_read_lock(); if (cpu_id >= 0) { @@ -395,9 +407,9 @@ static int membarrier_private_expedited(int flags, int cpu_id) * membarrier, we will end up with some thread in the mm * running without a core sync. * - * For RSEQ, don't rseq_preempt() the caller. User code - * is not supposed to issue syscalls at all from inside an - * rseq critical section. + * For RSEQ, don't invoke rseq_sched_switch_event() on the + * caller. User code is not supposed to issue syscalls at + * all from inside an rseq critical section. */ if (flags != MEMBARRIER_FLAG_SYNC_CORE) { preempt_disable(); @@ -415,7 +427,7 @@ out: /* * Memory barrier on the caller thread _after_ we finished - * waiting for the last IPI. Matches memory barriers around + * waiting for the last IPI. Matches memory barriers before * rq->curr modification in scheduler. */ smp_mb(); /* exit from system call is not a mb */ @@ -460,6 +472,7 @@ static int sync_runqueues_membarrier_state(struct mm_struct *mm) * between threads which are users of @mm has its membarrier state * updated. */ + SERIALIZE_IPI(); cpus_read_lock(); rcu_read_lock(); for_each_online_cpu(cpu) { |