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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Switch a MMU context.
*
* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
*/
#ifndef _ASM_MMU_CONTEXT_H
#define _ASM_MMU_CONTEXT_H
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/mm_types.h>
#include <linux/smp.h>
#include <linux/slab.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm-generic/mm_hooks.h>
/*
* All unused by hardware upper bits will be considered
* as a software asid extension.
*/
static inline u64 asid_version_mask(unsigned int cpu)
{
return ~(u64)(cpu_asid_mask(&cpu_data[cpu]));
}
static inline u64 asid_first_version(unsigned int cpu)
{
return cpu_asid_mask(&cpu_data[cpu]) + 1;
}
#define cpu_context(cpu, mm) ((mm)->context.asid[cpu])
#define asid_cache(cpu) (cpu_data[cpu].asid_cache)
#define cpu_asid(cpu, mm) (cpu_context((cpu), (mm)) & cpu_asid_mask(&cpu_data[cpu]))
static inline int asid_valid(struct mm_struct *mm, unsigned int cpu)
{
if ((cpu_context(cpu, mm) ^ asid_cache(cpu)) & asid_version_mask(cpu))
return 0;
return 1;
}
static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
}
/* Normal, classic get_new_mmu_context */
static inline void
get_new_mmu_context(struct mm_struct *mm, unsigned long cpu, bool *need_flush)
{
u64 asid = asid_cache(cpu);
if (!((++asid) & cpu_asid_mask(&cpu_data[cpu])))
*need_flush = true; /* start new asid cycle */
cpu_context(cpu, mm) = asid_cache(cpu) = asid;
}
/*
* Initialize the context related info for a new mm_struct
* instance.
*/
static inline int
init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
int i;
for_each_possible_cpu(i)
cpu_context(i, mm) = 0;
return 0;
}
static inline void atomic_update_pgd_asid(unsigned long asid, unsigned long pgdl)
{
__asm__ __volatile__(
"csrwr %[pgdl_val], %[pgdl_reg] \n\t"
"csrwr %[asid_val], %[asid_reg] \n\t"
: [asid_val] "+r" (asid), [pgdl_val] "+r" (pgdl)
: [asid_reg] "i" (LOONGARCH_CSR_ASID), [pgdl_reg] "i" (LOONGARCH_CSR_PGDL)
: "memory"
);
}
static inline void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
bool need_flush = false;
unsigned int cpu = smp_processor_id();
/* Check if our ASID is of an older version and thus invalid */
if (!asid_valid(next, cpu))
get_new_mmu_context(next, cpu, &need_flush);
if (next != &init_mm)
atomic_update_pgd_asid(cpu_asid(cpu, next), (unsigned long)next->pgd);
else
atomic_update_pgd_asid(cpu_asid(cpu, next), (unsigned long)invalid_pg_dir);
if (need_flush)
local_flush_tlb_user(); /* Flush tlb after update ASID */
/*
* Mark current->active_mm as not "active" anymore.
* We don't want to mislead possible IPI tlb flush routines.
*/
cpumask_set_cpu(cpu, mm_cpumask(next));
}
#define switch_mm_irqs_off switch_mm_irqs_off
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
unsigned long flags;
local_irq_save(flags);
switch_mm_irqs_off(prev, next, tsk);
local_irq_restore(flags);
}
/*
* Destroy context related info for an mm_struct that is about
* to be put to rest.
*/
static inline void destroy_context(struct mm_struct *mm)
{
}
#define activate_mm(prev, next) switch_mm(prev, next, current)
#define deactivate_mm(task, mm) do { } while (0)
/*
* If mm is currently active, we can't really drop it.
* Instead, we will get a new one for it.
*/
static inline void
drop_mmu_context(struct mm_struct *mm, unsigned int cpu)
{
int asid;
unsigned long flags;
local_irq_save(flags);
asid = read_csr_asid() & cpu_asid_mask(¤t_cpu_data);
if (asid == cpu_asid(cpu, mm)) {
bool need_flush = false;
if (!current->mm || (current->mm == mm)) {
get_new_mmu_context(mm, cpu, &need_flush);
write_csr_asid(cpu_asid(cpu, mm));
if (need_flush)
local_flush_tlb_user(); /* Flush tlb after update ASID */
goto out;
}
}
/* Will get a new context next time */
cpu_context(cpu, mm) = 0;
cpumask_clear_cpu(cpu, mm_cpumask(mm));
out:
local_irq_restore(flags);
}
#endif /* _ASM_MMU_CONTEXT_H */
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