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

ops-common.c (3193B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Common Primitives for Data Access Monitoring
      4 *
      5 * Author: SeongJae Park <sj@kernel.org>
      6 */
      7
      8#include <linux/mmu_notifier.h>
      9#include <linux/page_idle.h>
     10#include <linux/pagemap.h>
     11#include <linux/rmap.h>
     12
     13#include "ops-common.h"
     14
     15/*
     16 * Get an online page for a pfn if it's in the LRU list.  Otherwise, returns
     17 * NULL.
     18 *
     19 * The body of this function is stolen from the 'page_idle_get_page()'.  We
     20 * steal rather than reuse it because the code is quite simple.
     21 */
     22struct page *damon_get_page(unsigned long pfn)
     23{
     24	struct page *page = pfn_to_online_page(pfn);
     25
     26	if (!page || !PageLRU(page) || !get_page_unless_zero(page))
     27		return NULL;
     28
     29	if (unlikely(!PageLRU(page))) {
     30		put_page(page);
     31		page = NULL;
     32	}
     33	return page;
     34}
     35
     36void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr)
     37{
     38	bool referenced = false;
     39	struct page *page = damon_get_page(pte_pfn(*pte));
     40
     41	if (!page)
     42		return;
     43
     44	if (pte_young(*pte)) {
     45		referenced = true;
     46		*pte = pte_mkold(*pte);
     47	}
     48
     49#ifdef CONFIG_MMU_NOTIFIER
     50	if (mmu_notifier_clear_young(mm, addr, addr + PAGE_SIZE))
     51		referenced = true;
     52#endif /* CONFIG_MMU_NOTIFIER */
     53
     54	if (referenced)
     55		set_page_young(page);
     56
     57	set_page_idle(page);
     58	put_page(page);
     59}
     60
     61void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr)
     62{
     63#ifdef CONFIG_TRANSPARENT_HUGEPAGE
     64	bool referenced = false;
     65	struct page *page = damon_get_page(pmd_pfn(*pmd));
     66
     67	if (!page)
     68		return;
     69
     70	if (pmd_young(*pmd)) {
     71		referenced = true;
     72		*pmd = pmd_mkold(*pmd);
     73	}
     74
     75#ifdef CONFIG_MMU_NOTIFIER
     76	if (mmu_notifier_clear_young(mm, addr, addr + HPAGE_PMD_SIZE))
     77		referenced = true;
     78#endif /* CONFIG_MMU_NOTIFIER */
     79
     80	if (referenced)
     81		set_page_young(page);
     82
     83	set_page_idle(page);
     84	put_page(page);
     85#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
     86}
     87
     88#define DAMON_MAX_SUBSCORE	(100)
     89#define DAMON_MAX_AGE_IN_LOG	(32)
     90
     91int damon_pageout_score(struct damon_ctx *c, struct damon_region *r,
     92			struct damos *s)
     93{
     94	unsigned int max_nr_accesses;
     95	int freq_subscore;
     96	unsigned int age_in_sec;
     97	int age_in_log, age_subscore;
     98	unsigned int freq_weight = s->quota.weight_nr_accesses;
     99	unsigned int age_weight = s->quota.weight_age;
    100	int hotness;
    101
    102	max_nr_accesses = c->aggr_interval / c->sample_interval;
    103	freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE / max_nr_accesses;
    104
    105	age_in_sec = (unsigned long)r->age * c->aggr_interval / 1000000;
    106	for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec;
    107			age_in_log++, age_in_sec >>= 1)
    108		;
    109
    110	/* If frequency is 0, higher age means it's colder */
    111	if (freq_subscore == 0)
    112		age_in_log *= -1;
    113
    114	/*
    115	 * Now age_in_log is in [-DAMON_MAX_AGE_IN_LOG, DAMON_MAX_AGE_IN_LOG].
    116	 * Scale it to be in [0, 100] and set it as age subscore.
    117	 */
    118	age_in_log += DAMON_MAX_AGE_IN_LOG;
    119	age_subscore = age_in_log * DAMON_MAX_SUBSCORE /
    120		DAMON_MAX_AGE_IN_LOG / 2;
    121
    122	hotness = (freq_weight * freq_subscore + age_weight * age_subscore);
    123	if (freq_weight + age_weight)
    124		hotness /= freq_weight + age_weight;
    125	/*
    126	 * Transform it to fit in [0, DAMOS_MAX_SCORE]
    127	 */
    128	hotness = hotness * DAMOS_MAX_SCORE / DAMON_MAX_SUBSCORE;
    129
    130	/* Return coldness of the region */
    131	return DAMOS_MAX_SCORE - hotness;
    132}