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/*
* Copyright (C) 2012 Regents of the University of California
* Copyright (C) 2017 SiFive
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#ifndef _ASM_RISCV_MMU_CONTEXT_H
#define _ASM_RISCV_MMU_CONTEXT_H
#include <linux/mm_types.h>
#include <asm-generic/mm_hooks.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
static inline void enter_lazy_tlb(struct mm_struct *mm,
struct task_struct *task)
{
}
/* Initialize context-related info for a new mm_struct */
static inline int init_new_context(struct task_struct *task,
struct mm_struct *mm)
{
return 0;
}
static inline void destroy_context(struct mm_struct *mm)
{
}
static inline pgd_t *current_pgdir(void)
{
return pfn_to_virt(csr_read(sptbr) & SPTBR_PPN);
}
static inline void set_pgdir(pgd_t *pgd)
{
csr_write(sptbr, virt_to_pfn(pgd) | SPTBR_MODE);
}
/*
* When necessary, performs a deferred icache flush for the given MM context,
* on the local CPU. RISC-V has no direct mechanism for instruction cache
* shoot downs, so instead we send an IPI that informs the remote harts they
* need to flush their local instruction caches. To avoid pathologically slow
* behavior in a common case (a bunch of single-hart processes on a many-hart
* machine, ie 'make -j') we avoid the IPIs for harts that are not currently
* executing a MM context and instead schedule a deferred local instruction
* cache flush to be performed before execution resumes on each hart. This
* actually performs that local instruction cache flush, which implicitly only
* refers to the current hart.
*/
static inline void flush_icache_deferred(struct mm_struct *mm)
{
#ifdef CONFIG_SMP
unsigned int cpu = smp_processor_id();
cpumask_t *mask = &mm->context.icache_stale_mask;
if (cpumask_test_cpu(cpu, mask)) {
cpumask_clear_cpu(cpu, mask);
/*
* Ensure the remote hart's writes are visible to this hart.
* This pairs with a barrier in flush_icache_mm.
*/
smp_mb();
local_flush_icache_all();
}
#endif
}
static inline void switch_mm(struct mm_struct *prev,
struct mm_struct *next, struct task_struct *task)
{
if (likely(prev != next)) {
/*
* Mark the current MM context as inactive, and the next as
* active. This is at least used by the icache flushing
* routines in order to determine who should
*/
unsigned int cpu = smp_processor_id();
cpumask_clear_cpu(cpu, mm_cpumask(prev));
cpumask_set_cpu(cpu, mm_cpumask(next));
set_pgdir(next->pgd);
local_flush_tlb_all();
flush_icache_deferred(next);
}
}
static inline void activate_mm(struct mm_struct *prev,
struct mm_struct *next)
{
switch_mm(prev, next, NULL);
}
static inline void deactivate_mm(struct task_struct *task,
struct mm_struct *mm)
{
}
#endif /* _ASM_RISCV_MMU_CONTEXT_H */
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