cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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mmu_context.h (3561B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2/*
      3 * Switch a MMU context.
      4 *
      5 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
      6 */
      7#ifndef _ASM_MMU_CONTEXT_H
      8#define _ASM_MMU_CONTEXT_H
      9
     10#include <linux/errno.h>
     11#include <linux/sched.h>
     12#include <linux/mm_types.h>
     13#include <linux/smp.h>
     14#include <linux/slab.h>
     15
     16#include <asm/cacheflush.h>
     17#include <asm/tlbflush.h>
     18#include <asm-generic/mm_hooks.h>
     19
     20/*
     21 *  All unused by hardware upper bits will be considered
     22 *  as a software asid extension.
     23 */
     24static inline u64 asid_version_mask(unsigned int cpu)
     25{
     26	return ~(u64)(cpu_asid_mask(&cpu_data[cpu]));
     27}
     28
     29static inline u64 asid_first_version(unsigned int cpu)
     30{
     31	return cpu_asid_mask(&cpu_data[cpu]) + 1;
     32}
     33
     34#define cpu_context(cpu, mm)	((mm)->context.asid[cpu])
     35#define asid_cache(cpu)		(cpu_data[cpu].asid_cache)
     36#define cpu_asid(cpu, mm)	(cpu_context((cpu), (mm)) & cpu_asid_mask(&cpu_data[cpu]))
     37
     38static inline int asid_valid(struct mm_struct *mm, unsigned int cpu)
     39{
     40	if ((cpu_context(cpu, mm) ^ asid_cache(cpu)) & asid_version_mask(cpu))
     41		return 0;
     42
     43	return 1;
     44}
     45
     46static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
     47{
     48}
     49
     50/* Normal, classic get_new_mmu_context */
     51static inline void
     52get_new_mmu_context(struct mm_struct *mm, unsigned long cpu)
     53{
     54	u64 asid = asid_cache(cpu);
     55
     56	if (!((++asid) & cpu_asid_mask(&cpu_data[cpu])))
     57		local_flush_tlb_user();	/* start new asid cycle */
     58
     59	cpu_context(cpu, mm) = asid_cache(cpu) = asid;
     60}
     61
     62/*
     63 * Initialize the context related info for a new mm_struct
     64 * instance.
     65 */
     66static inline int
     67init_new_context(struct task_struct *tsk, struct mm_struct *mm)
     68{
     69	int i;
     70
     71	for_each_possible_cpu(i)
     72		cpu_context(i, mm) = 0;
     73
     74	return 0;
     75}
     76
     77static inline void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
     78				      struct task_struct *tsk)
     79{
     80	unsigned int cpu = smp_processor_id();
     81
     82	/* Check if our ASID is of an older version and thus invalid */
     83	if (!asid_valid(next, cpu))
     84		get_new_mmu_context(next, cpu);
     85
     86	write_csr_asid(cpu_asid(cpu, next));
     87
     88	if (next != &init_mm)
     89		csr_write64((unsigned long)next->pgd, LOONGARCH_CSR_PGDL);
     90	else
     91		csr_write64((unsigned long)invalid_pg_dir, LOONGARCH_CSR_PGDL);
     92
     93	/*
     94	 * Mark current->active_mm as not "active" anymore.
     95	 * We don't want to mislead possible IPI tlb flush routines.
     96	 */
     97	cpumask_set_cpu(cpu, mm_cpumask(next));
     98}
     99
    100#define switch_mm_irqs_off switch_mm_irqs_off
    101
    102static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
    103			     struct task_struct *tsk)
    104{
    105	unsigned long flags;
    106
    107	local_irq_save(flags);
    108	switch_mm_irqs_off(prev, next, tsk);
    109	local_irq_restore(flags);
    110}
    111
    112/*
    113 * Destroy context related info for an mm_struct that is about
    114 * to be put to rest.
    115 */
    116static inline void destroy_context(struct mm_struct *mm)
    117{
    118}
    119
    120#define activate_mm(prev, next)	switch_mm(prev, next, current)
    121#define deactivate_mm(task, mm)	do { } while (0)
    122
    123/*
    124 * If mm is currently active, we can't really drop it.
    125 * Instead, we will get a new one for it.
    126 */
    127static inline void
    128drop_mmu_context(struct mm_struct *mm, unsigned int cpu)
    129{
    130	int asid;
    131	unsigned long flags;
    132
    133	local_irq_save(flags);
    134
    135	asid = read_csr_asid() & cpu_asid_mask(&current_cpu_data);
    136
    137	if (asid == cpu_asid(cpu, mm)) {
    138		if (!current->mm || (current->mm == mm)) {
    139			get_new_mmu_context(mm, cpu);
    140			write_csr_asid(cpu_asid(cpu, mm));
    141			goto out;
    142		}
    143	}
    144
    145	/* Will get a new context next time */
    146	cpu_context(cpu, mm) = 0;
    147	cpumask_clear_cpu(cpu, mm_cpumask(mm));
    148out:
    149	local_irq_restore(flags);
    150}
    151
    152#endif /* _ASM_MMU_CONTEXT_H */