Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
sched/membarrier: Introduce MEMBARRIER_CMD_GET_REGISTRATIONS
Provide a method to query previously issued registrations.
Signed-off-by: Michal Clapinski <mclapinski@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20221207164338.1535591-2-mclapinski@google.com
authored by
Michal Clapinski
and committed by
Ingo Molnar
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include/uapi/linux/membarrier.h
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include/uapi/linux/membarrier.h
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* @MEMBARRIER_CMD_SHARED:
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* Alias to MEMBARRIER_CMD_GLOBAL. Provided for
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* header backward compatibility.
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* @MEMBARRIER_CMD_GET_REGISTRATIONS:
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* Returns a bitmask of previously issued
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* registration commands.
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*
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* Command to be passed to the membarrier system call. The commands need to
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* be a single bit each, except for MEMBARRIER_CMD_QUERY which is assigned to
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MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE = (1 << 6),
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MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ = (1 << 7),
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MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ = (1 << 8),
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MEMBARRIER_CMD_GET_REGISTRATIONS = (1 << 9),
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/* Alias for header backward compatibility. */
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MEMBARRIER_CMD_SHARED = MEMBARRIER_CMD_GLOBAL,
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kernel/sched/membarrier.c
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kernel/sched/membarrier.c
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| MEMBARRIER_CMD_PRIVATE_EXPEDITED \
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| MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED \
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| MEMBARRIER_PRIVATE_EXPEDITED_SYNC_CORE_BITMASK \
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-
| MEMBARRIER_PRIVATE_EXPEDITED_RSEQ_BITMASK)
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| MEMBARRIER_PRIVATE_EXPEDITED_RSEQ_BITMASK \
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| MEMBARRIER_CMD_GET_REGISTRATIONS)
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static void ipi_mb(void *info)
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{
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return 0;
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}
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static int membarrier_get_registrations(void)
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{
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struct task_struct *p = current;
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struct mm_struct *mm = p->mm;
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int registrations_mask = 0, membarrier_state, i;
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static const int states[] = {
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MEMBARRIER_STATE_GLOBAL_EXPEDITED |
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MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY,
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MEMBARRIER_STATE_PRIVATE_EXPEDITED |
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MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY,
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MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE |
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MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY,
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MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ |
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MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ_READY
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};
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static const int registration_cmds[] = {
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MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED,
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MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED,
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MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE,
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MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ
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};
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BUILD_BUG_ON(ARRAY_SIZE(states) != ARRAY_SIZE(registration_cmds));
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membarrier_state = atomic_read(&mm->membarrier_state);
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for (i = 0; i < ARRAY_SIZE(states); ++i) {
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if (membarrier_state & states[i]) {
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registrations_mask |= registration_cmds[i];
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membarrier_state &= ~states[i];
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}
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}
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WARN_ON_ONCE(membarrier_state != 0);
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return registrations_mask;
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}
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/**
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* sys_membarrier - issue memory barriers on a set of threads
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* @cmd: Takes command values defined in enum membarrier_cmd.
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return membarrier_private_expedited(MEMBARRIER_FLAG_RSEQ, cpu_id);
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case MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ:
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return membarrier_register_private_expedited(MEMBARRIER_FLAG_RSEQ);
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case MEMBARRIER_CMD_GET_REGISTRATIONS:
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return membarrier_get_registrations();
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default:
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return -EINVAL;
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}