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.c (3102B)

      1/*
      2 * MMU context handling.
      3 *
      4 * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
      5 * Copyright (C) 2009 Wind River Systems Inc
      6 *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
      7 *
      8 * This file is subject to the terms and conditions of the GNU General Public
      9 * License.  See the file "COPYING" in the main directory of this archive
     10 * for more details.
     11 */
     12
     13#include <linux/mm.h>
     14
     15#include <asm/cpuinfo.h>
     16#include <asm/mmu_context.h>
     17#include <asm/tlb.h>
     18
     19/* The pids position and mask in context */
     20#define PID_SHIFT	0
     21#define PID_BITS	(cpuinfo.tlb_pid_num_bits)
     22#define PID_MASK	((1UL << PID_BITS) - 1)
     23
     24/* The versions position and mask in context */
     25#define VERSION_BITS	(32 - PID_BITS)
     26#define VERSION_SHIFT	(PID_SHIFT + PID_BITS)
     27#define VERSION_MASK	((1UL << VERSION_BITS) - 1)
     28
     29/* Return the version part of a context */
     30#define CTX_VERSION(c)	(((c) >> VERSION_SHIFT) & VERSION_MASK)
     31
     32/* Return the pid part of a context */
     33#define CTX_PID(c)	(((c) >> PID_SHIFT) & PID_MASK)
     34
     35/* Value of the first context (version 1, pid 0) */
     36#define FIRST_CTX	((1UL << VERSION_SHIFT) | (0 << PID_SHIFT))
     37
     38static mm_context_t next_mmu_context;
     39
     40/*
     41 * Initialize MMU context management stuff.
     42 */
     43void __init mmu_context_init(void)
     44{
     45	/* We need to set this here because the value depends on runtime data
     46	 * from cpuinfo */
     47	next_mmu_context = FIRST_CTX;
     48}
     49
     50/*
     51 * Set new context (pid), keep way
     52 */
     53static void set_context(mm_context_t context)
     54{
     55	set_mmu_pid(CTX_PID(context));
     56}
     57
     58static mm_context_t get_new_context(void)
     59{
     60	/* Return the next pid */
     61	next_mmu_context += (1UL << PID_SHIFT);
     62
     63	/* If the pid field wraps around we increase the version and
     64	 * flush the tlb */
     65	if (unlikely(CTX_PID(next_mmu_context) == 0)) {
     66		/* Version is incremented since the pid increment above
     67		 * overflows info version */
     68		flush_cache_all();
     69		flush_tlb_all();
     70	}
     71
     72	/* If the version wraps we start over with the first generation, we do
     73	 * not need to flush the tlb here since it's always done above */
     74	if (unlikely(CTX_VERSION(next_mmu_context) == 0))
     75		next_mmu_context = FIRST_CTX;
     76
     77	return next_mmu_context;
     78}
     79
     80void switch_mm(struct mm_struct *prev, struct mm_struct *next,
     81	       struct task_struct *tsk)
     82{
     83	unsigned long flags;
     84
     85	local_irq_save(flags);
     86
     87	/* If the process context we are swapping in has a different context
     88	 * generation then we have it should get a new generation/pid */
     89	if (unlikely(CTX_VERSION(next->context) !=
     90		CTX_VERSION(next_mmu_context)))
     91		next->context = get_new_context();
     92
     93	/* Save the current pgd so the fast tlb handler can find it */
     94	pgd_current = next->pgd;
     95
     96	/* Set the current context */
     97	set_context(next->context);
     98
     99	local_irq_restore(flags);
    100}
    101
    102/*
    103 * After we have set current->mm to a new value, this activates
    104 * the context for the new mm so we see the new mappings.
    105 */
    106void activate_mm(struct mm_struct *prev, struct mm_struct *next)
    107{
    108	next->context = get_new_context();
    109	set_context(next->context);
    110	pgd_current = next->pgd;
    111}
    112
    113unsigned long get_pid_from_context(mm_context_t *context)
    114{
    115	return CTX_PID((*context));
    116}