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The RISC-V ISA only supports flushing the instruction cache for the local CPU core. Currently we always offload the remote TLB flushing to the SBI, which then issues an IPI under the hoods. But with M-mode we do not have an SBI so we have to do it ourselves. IPI to the other nodes using the existing kernel helpers instead if we have native clint support and thus can IPI directly from the kernel. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Anup Patel <anup@brainfault.org> [paul.walmsley@sifive.com: cleaned up code comment] Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
88 lines
2.4 KiB
C
88 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2017 SiFive
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*/
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#include <asm/pgtable.h>
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#include <asm/cacheflush.h>
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#ifdef CONFIG_SMP
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#include <asm/sbi.h>
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static void ipi_remote_fence_i(void *info)
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{
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return local_flush_icache_all();
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}
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void flush_icache_all(void)
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{
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if (IS_ENABLED(CONFIG_RISCV_SBI))
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sbi_remote_fence_i(NULL);
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else
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on_each_cpu(ipi_remote_fence_i, NULL, 1);
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}
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/*
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* Performs an icache flush for the given MM context. RISC-V has no direct
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* mechanism for instruction cache shoot downs, so instead we send an IPI that
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* informs the remote harts they need to flush their local instruction caches.
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* To avoid pathologically slow behavior in a common case (a bunch of
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* single-hart processes on a many-hart machine, ie 'make -j') we avoid the
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* IPIs for harts that are not currently executing a MM context and instead
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* schedule a deferred local instruction cache flush to be performed before
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* execution resumes on each hart.
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*/
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void flush_icache_mm(struct mm_struct *mm, bool local)
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{
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unsigned int cpu;
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cpumask_t others, *mask;
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preempt_disable();
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/* Mark every hart's icache as needing a flush for this MM. */
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mask = &mm->context.icache_stale_mask;
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cpumask_setall(mask);
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/* Flush this hart's I$ now, and mark it as flushed. */
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cpu = smp_processor_id();
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cpumask_clear_cpu(cpu, mask);
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local_flush_icache_all();
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/*
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* Flush the I$ of other harts concurrently executing, and mark them as
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* flushed.
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*/
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cpumask_andnot(&others, mm_cpumask(mm), cpumask_of(cpu));
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local |= cpumask_empty(&others);
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if (mm == current->active_mm && local) {
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/*
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* It's assumed that at least one strongly ordered operation is
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* performed on this hart between setting a hart's cpumask bit
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* and scheduling this MM context on that hart. Sending an SBI
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* remote message will do this, but in the case where no
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* messages are sent we still need to order this hart's writes
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* with flush_icache_deferred().
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*/
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smp_mb();
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} else if (IS_ENABLED(CONFIG_RISCV_SBI)) {
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cpumask_t hartid_mask;
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riscv_cpuid_to_hartid_mask(&others, &hartid_mask);
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sbi_remote_fence_i(cpumask_bits(&hartid_mask));
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} else {
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on_each_cpu_mask(&others, ipi_remote_fence_i, NULL, 1);
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}
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preempt_enable();
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}
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#endif /* CONFIG_SMP */
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void flush_icache_pte(pte_t pte)
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{
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struct page *page = pte_page(pte);
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if (!test_and_set_bit(PG_dcache_clean, &page->flags))
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flush_icache_all();
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}
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