diff options
| -rw-r--r-- | MAINTAINERS | 2 | ||||
| -rw-r--r-- | arch/riscv/Kconfig | 1 | ||||
| -rw-r--r-- | arch/riscv/include/asm/membarrier.h | 31 | ||||
| -rw-r--r-- | arch/riscv/mm/context.c | 2 | ||||
| -rw-r--r-- | kernel/sched/core.c | 5 |
5 files changed, 38 insertions, 3 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 8d1052fa6a69..2450e88d3e2c 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -14039,7 +14039,7 @@ M: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> M: "Paul E. McKenney" <paulmck@kernel.org> L: linux-kernel@vger.kernel.org S: Supported -F: arch/powerpc/include/asm/membarrier.h +F: arch/*/include/asm/membarrier.h F: include/uapi/linux/membarrier.h F: kernel/sched/membarrier.c diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index bffbd869a068..087abf9e51c6 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -27,6 +27,7 @@ config RISCV select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_GIGANTIC_PAGE select ARCH_HAS_KCOV + select ARCH_HAS_MEMBARRIER_CALLBACKS select ARCH_HAS_MMIOWB select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE select ARCH_HAS_PMEM_API diff --git a/arch/riscv/include/asm/membarrier.h b/arch/riscv/include/asm/membarrier.h new file mode 100644 index 000000000000..6c016ebb5020 --- /dev/null +++ b/arch/riscv/include/asm/membarrier.h @@ -0,0 +1,31 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef _ASM_RISCV_MEMBARRIER_H +#define _ASM_RISCV_MEMBARRIER_H + +static inline void membarrier_arch_switch_mm(struct mm_struct *prev, + struct mm_struct *next, + struct task_struct *tsk) +{ + /* + * Only need the full barrier when switching between processes. + * Barrier when switching from kernel to userspace is not + * required here, given that it is implied by mmdrop(). Barrier + * when switching from userspace to kernel is not needed after + * store to rq->curr. + */ + if (IS_ENABLED(CONFIG_SMP) && + likely(!(atomic_read(&next->membarrier_state) & + (MEMBARRIER_STATE_PRIVATE_EXPEDITED | + MEMBARRIER_STATE_GLOBAL_EXPEDITED)) || !prev)) + return; + + /* + * The membarrier system call requires a full memory barrier + * after storing to rq->curr, before going back to user-space. + * Matches a full barrier in the proximity of the membarrier + * system call entry. + */ + smp_mb(); +} + +#endif /* _ASM_RISCV_MEMBARRIER_H */ diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c index 217fd4de6134..ba8eb3944687 100644 --- a/arch/riscv/mm/context.c +++ b/arch/riscv/mm/context.c @@ -323,6 +323,8 @@ void switch_mm(struct mm_struct *prev, struct mm_struct *next, if (unlikely(prev == next)) return; + membarrier_arch_switch_mm(prev, next, task); + /* * Mark the current MM context as inactive, and the next as * active. This is at least used by the icache flushing diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9116bcc90346..c4ca8085885a 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6709,8 +6709,9 @@ static void __sched notrace __schedule(unsigned int sched_mode) * * Here are the schemes providing that barrier on the * various architectures: - * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC. - * switch_mm() rely on membarrier_arch_switch_mm() on PowerPC. + * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC, + * RISC-V. switch_mm() relies on membarrier_arch_switch_mm() + * on PowerPC and on RISC-V. * - finish_lock_switch() for weakly-ordered * architectures where spin_unlock is a full barrier, * - switch_to() for arm64 (weakly-ordered, spin_unlock |