1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2012 Regents of the University of California
4 * Copyright (C) 2017 SiFive
8 #include <asm/tlbflush.h>
9 #include <asm/cacheflush.h>
12 * When necessary, performs a deferred icache flush for the given MM context,
13 * on the local CPU. RISC-V has no direct mechanism for instruction cache
14 * shoot downs, so instead we send an IPI that informs the remote harts they
15 * need to flush their local instruction caches. To avoid pathologically slow
16 * behavior in a common case (a bunch of single-hart processes on a many-hart
17 * machine, ie 'make -j') we avoid the IPIs for harts that are not currently
18 * executing a MM context and instead schedule a deferred local instruction
19 * cache flush to be performed before execution resumes on each hart. This
20 * actually performs that local instruction cache flush, which implicitly only
21 * refers to the current hart.
23 static inline void flush_icache_deferred(struct mm_struct *mm)
26 unsigned int cpu = smp_processor_id();
27 cpumask_t *mask = &mm->context.icache_stale_mask;
29 if (cpumask_test_cpu(cpu, mask)) {
30 cpumask_clear_cpu(cpu, mask);
32 * Ensure the remote hart's writes are visible to this hart.
33 * This pairs with a barrier in flush_icache_mm.
36 local_flush_icache_all();
42 void switch_mm(struct mm_struct *prev, struct mm_struct *next,
43 struct task_struct *task)
47 if (unlikely(prev == next))
51 * Mark the current MM context as inactive, and the next as
52 * active. This is at least used by the icache flushing
53 * routines in order to determine who should be flushed.
55 cpu = smp_processor_id();
57 cpumask_clear_cpu(cpu, mm_cpumask(prev));
58 cpumask_set_cpu(cpu, mm_cpumask(next));
60 csr_write(CSR_SATP, virt_to_pfn(next->pgd) | SATP_MODE);
61 local_flush_tlb_all();
63 flush_icache_deferred(next);