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5b2a152962
When analysing sources of OS jitter, I noticed that doorbells cannot be traced. Signed-off-by: Anton Blanchard <anton@ozlabs.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
107 lines
2.5 KiB
C
107 lines
2.5 KiB
C
/*
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* Author: Kumar Gala <galak@kernel.crashing.org>
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*
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* Copyright 2009 Freescale Semiconductor Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include <linux/stddef.h>
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#include <linux/kernel.h>
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#include <linux/smp.h>
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#include <linux/threads.h>
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#include <linux/hardirq.h>
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#include <asm/dbell.h>
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#include <asm/irq_regs.h>
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#include <asm/kvm_ppc.h>
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#include <asm/trace.h>
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#ifdef CONFIG_SMP
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/*
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* Doorbells must only be used if CPU_FTR_DBELL is available.
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* msgsnd is used in HV, and msgsndp is used in !HV.
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*
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* These should be used by platform code that is aware of restrictions.
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* Other arch code should use ->cause_ipi.
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*
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* doorbell_global_ipi() sends a dbell to any target CPU.
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* Must be used only by architectures that address msgsnd target
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* by PIR/get_hard_smp_processor_id.
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*/
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void doorbell_global_ipi(int cpu)
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{
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u32 tag = get_hard_smp_processor_id(cpu);
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kvmppc_set_host_ipi(cpu, 1);
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/* Order previous accesses vs. msgsnd, which is treated as a store */
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ppc_msgsnd_sync();
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ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, tag);
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}
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/*
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* doorbell_core_ipi() sends a dbell to a target CPU in the same core.
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* Must be used only by architectures that address msgsnd target
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* by TIR/cpu_thread_in_core.
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*/
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void doorbell_core_ipi(int cpu)
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{
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u32 tag = cpu_thread_in_core(cpu);
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kvmppc_set_host_ipi(cpu, 1);
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/* Order previous accesses vs. msgsnd, which is treated as a store */
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ppc_msgsnd_sync();
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ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, tag);
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}
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/*
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* Attempt to cause a core doorbell if destination is on the same core.
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* Returns 1 on success, 0 on failure.
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*/
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int doorbell_try_core_ipi(int cpu)
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{
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int this_cpu = get_cpu();
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int ret = 0;
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if (cpumask_test_cpu(cpu, cpu_sibling_mask(this_cpu))) {
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doorbell_core_ipi(cpu);
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ret = 1;
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}
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put_cpu();
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return ret;
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}
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void doorbell_exception(struct pt_regs *regs)
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{
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struct pt_regs *old_regs = set_irq_regs(regs);
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irq_enter();
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trace_doorbell_entry(regs);
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ppc_msgsync();
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may_hard_irq_enable();
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kvmppc_set_host_ipi(smp_processor_id(), 0);
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__this_cpu_inc(irq_stat.doorbell_irqs);
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smp_ipi_demux_relaxed(); /* already performed the barrier */
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trace_doorbell_exit(regs);
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irq_exit();
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set_irq_regs(old_regs);
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}
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#else /* CONFIG_SMP */
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void doorbell_exception(struct pt_regs *regs)
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{
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printk(KERN_WARNING "Received doorbell on non-smp system\n");
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}
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#endif /* CONFIG_SMP */
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