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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percpu-km.c (3240B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * mm/percpu-km.c - kernel memory based chunk allocation
      4 *
      5 * Copyright (C) 2010		SUSE Linux Products GmbH
      6 * Copyright (C) 2010		Tejun Heo <tj@kernel.org>
      7 *
      8 * Chunks are allocated as a contiguous kernel memory using gfp
      9 * allocation.  This is to be used on nommu architectures.
     10 *
     11 * To use percpu-km,
     12 *
     13 * - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig.
     14 *
     15 * - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined.  It's
     16 *   not compatible with PER_CPU_KM.  EMBED_FIRST_CHUNK should work
     17 *   fine.
     18 *
     19 * - NUMA is not supported.  When setting up the first chunk,
     20 *   @cpu_distance_fn should be NULL or report all CPUs to be nearer
     21 *   than or at LOCAL_DISTANCE.
     22 *
     23 * - It's best if the chunk size is power of two multiple of
     24 *   PAGE_SIZE.  Because each chunk is allocated as a contiguous
     25 *   kernel memory block using alloc_pages(), memory will be wasted if
     26 *   chunk size is not aligned.  percpu-km code will whine about it.
     27 */
     28
     29#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
     30#error "contiguous percpu allocation is incompatible with paged first chunk"
     31#endif
     32
     33#include <linux/log2.h>
     34
     35static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
     36				      int page_start, int page_end)
     37{
     38	/* nothing */
     39}
     40
     41static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
     42			       int page_start, int page_end, gfp_t gfp)
     43{
     44	return 0;
     45}
     46
     47static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
     48				  int page_start, int page_end)
     49{
     50	/* nada */
     51}
     52
     53static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
     54{
     55	const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
     56	struct pcpu_chunk *chunk;
     57	struct page *pages;
     58	unsigned long flags;
     59	int i;
     60
     61	chunk = pcpu_alloc_chunk(gfp);
     62	if (!chunk)
     63		return NULL;
     64
     65	pages = alloc_pages(gfp, order_base_2(nr_pages));
     66	if (!pages) {
     67		pcpu_free_chunk(chunk);
     68		return NULL;
     69	}
     70
     71	for (i = 0; i < nr_pages; i++)
     72		pcpu_set_page_chunk(nth_page(pages, i), chunk);
     73
     74	chunk->data = pages;
     75	chunk->base_addr = page_address(pages);
     76
     77	spin_lock_irqsave(&pcpu_lock, flags);
     78	pcpu_chunk_populated(chunk, 0, nr_pages);
     79	spin_unlock_irqrestore(&pcpu_lock, flags);
     80
     81	pcpu_stats_chunk_alloc();
     82	trace_percpu_create_chunk(chunk->base_addr);
     83
     84	return chunk;
     85}
     86
     87static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
     88{
     89	const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
     90
     91	if (!chunk)
     92		return;
     93
     94	pcpu_stats_chunk_dealloc();
     95	trace_percpu_destroy_chunk(chunk->base_addr);
     96
     97	if (chunk->data)
     98		__free_pages(chunk->data, order_base_2(nr_pages));
     99	pcpu_free_chunk(chunk);
    100}
    101
    102static struct page *pcpu_addr_to_page(void *addr)
    103{
    104	return virt_to_page(addr);
    105}
    106
    107static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
    108{
    109	size_t nr_pages, alloc_pages;
    110
    111	/* all units must be in a single group */
    112	if (ai->nr_groups != 1) {
    113		pr_crit("can't handle more than one group\n");
    114		return -EINVAL;
    115	}
    116
    117	nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT;
    118	alloc_pages = roundup_pow_of_two(nr_pages);
    119
    120	if (alloc_pages > nr_pages)
    121		pr_warn("wasting %zu pages per chunk\n",
    122			alloc_pages - nr_pages);
    123
    124	return 0;
    125}
    126
    127static bool pcpu_should_reclaim_chunk(struct pcpu_chunk *chunk)
    128{
    129	return false;
    130}