On Mon, Sep 09, 2024 at 10:57:01AM +0800, WangYuli wrote:
From: Andrea Parri parri.andrea@gmail.com
[ Upstream commit d6cfd1770f20392d7009ae1fdb04733794514fa9 ]
The membarrier system call requires a full memory barrier after storing to rq->curr, before going back to user-space. The barrier is only needed when switching between processes: the barrier is implied by mmdrop() when switching from kernel to userspace, and it's not needed when switching from userspace to kernel.
Rely on the feature/mechanism ARCH_HAS_MEMBARRIER_CALLBACKS and on the primitive membarrier_arch_switch_mm(), already adopted by the PowerPC architecture, to insert the required barrier.
Fixes: fab957c11efe2f ("RISC-V: Atomic and Locking Code") Signed-off-by: Andrea Parri parri.andrea@gmail.com Reviewed-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com Link: https://lore.kernel.org/r/20240131144936.29190-2-parri.andrea@gmail.com Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: WangYuli wangyuli@uniontech.com
MAINTAINERS | 2 +- arch/riscv/Kconfig | 1 + arch/riscv/include/asm/membarrier.h | 31 +++++++++++++++++++++++++++++ arch/riscv/mm/context.c | 2 ++ kernel/sched/core.c | 5 +++-- 5 files changed, 38 insertions(+), 3 deletions(-) create mode 100644 arch/riscv/include/asm/membarrier.h
Now queued up, thanks.
greg k-h