cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

mmu_context_mm.h (3893B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2/*
      3 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
      4 * Copyright (C) 2008-2009 PetaLogix
      5 * Copyright (C) 2006 Atmark Techno, Inc.
      6 */
      7
      8#ifndef _ASM_MICROBLAZE_MMU_CONTEXT_H
      9#define _ASM_MICROBLAZE_MMU_CONTEXT_H
     10
     11#include <linux/atomic.h>
     12#include <linux/mm_types.h>
     13#include <linux/sched.h>
     14
     15#include <asm/bitops.h>
     16#include <asm/mmu.h>
     17#include <asm-generic/mm_hooks.h>
     18
     19# ifdef __KERNEL__
     20/*
     21 * This function defines the mapping from contexts to VSIDs (virtual
     22 * segment IDs).  We use a skew on both the context and the high 4 bits
     23 * of the 32-bit virtual address (the "effective segment ID") in order
     24 * to spread out the entries in the MMU hash table.
     25 */
     26# define CTX_TO_VSID(ctx, va)	(((ctx) * (897 * 16) + ((va) >> 28) * 0x111) \
     27				 & 0xffffff)
     28
     29/*
     30   MicroBlaze has 256 contexts, so we can just rotate through these
     31   as a way of "switching" contexts.  If the TID of the TLB is zero,
     32   the PID/TID comparison is disabled, so we can use a TID of zero
     33   to represent all kernel pages as shared among all contexts.
     34 */
     35
     36# define NO_CONTEXT	256
     37# define LAST_CONTEXT	255
     38# define FIRST_CONTEXT	1
     39
     40/*
     41 * Set the current MMU context.
     42 * This is done byloading up the segment registers for the user part of the
     43 * address space.
     44 *
     45 * Since the PGD is immediately available, it is much faster to simply
     46 * pass this along as a second parameter, which is required for 8xx and
     47 * can be used for debugging on all processors (if you happen to have
     48 * an Abatron).
     49 */
     50extern void set_context(mm_context_t context, pgd_t *pgd);
     51
     52/*
     53 * Bitmap of contexts in use.
     54 * The size of this bitmap is LAST_CONTEXT + 1 bits.
     55 */
     56extern unsigned long context_map[];
     57
     58/*
     59 * This caches the next context number that we expect to be free.
     60 * Its use is an optimization only, we can't rely on this context
     61 * number to be free, but it usually will be.
     62 */
     63extern mm_context_t next_mmu_context;
     64
     65/*
     66 * Since we don't have sufficient contexts to give one to every task
     67 * that could be in the system, we need to be able to steal contexts.
     68 * These variables support that.
     69 */
     70extern atomic_t nr_free_contexts;
     71extern struct mm_struct *context_mm[LAST_CONTEXT+1];
     72extern void steal_context(void);
     73
     74/*
     75 * Get a new mmu context for the address space described by `mm'.
     76 */
     77static inline void get_mmu_context(struct mm_struct *mm)
     78{
     79	mm_context_t ctx;
     80
     81	if (mm->context != NO_CONTEXT)
     82		return;
     83	while (atomic_dec_if_positive(&nr_free_contexts) < 0)
     84		steal_context();
     85	ctx = next_mmu_context;
     86	while (test_and_set_bit(ctx, context_map)) {
     87		ctx = find_next_zero_bit(context_map, LAST_CONTEXT+1, ctx);
     88		if (ctx > LAST_CONTEXT)
     89			ctx = 0;
     90	}
     91	next_mmu_context = (ctx + 1) & LAST_CONTEXT;
     92	mm->context = ctx;
     93	context_mm[ctx] = mm;
     94}
     95
     96/*
     97 * Set up the context for a new address space.
     98 */
     99# define init_new_context(tsk, mm)	(((mm)->context = NO_CONTEXT), 0)
    100
    101/*
    102 * We're finished using the context for an address space.
    103 */
    104#define destroy_context destroy_context
    105static inline void destroy_context(struct mm_struct *mm)
    106{
    107	if (mm->context != NO_CONTEXT) {
    108		clear_bit(mm->context, context_map);
    109		mm->context = NO_CONTEXT;
    110		atomic_inc(&nr_free_contexts);
    111	}
    112}
    113
    114static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
    115			     struct task_struct *tsk)
    116{
    117	tsk->thread.pgdir = next->pgd;
    118	get_mmu_context(next);
    119	set_context(next->context, next->pgd);
    120}
    121
    122/*
    123 * After we have set current->mm to a new value, this activates
    124 * the context for the new mm so we see the new mappings.
    125 */
    126#define activate_mm activate_mm
    127static inline void activate_mm(struct mm_struct *active_mm,
    128			struct mm_struct *mm)
    129{
    130	current->thread.pgdir = mm->pgd;
    131	get_mmu_context(mm);
    132	set_context(mm->context, mm->pgd);
    133}
    134
    135extern void mmu_context_init(void);
    136
    137#include <asm-generic/mmu_context.h>
    138
    139# endif /* __KERNEL__ */
    140#endif /* _ASM_MICROBLAZE_MMU_CONTEXT_H */