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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packets-buffer.c (2102B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * helpers for managing a buffer for many packets
      4 *
      5 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
      6 */
      7
      8#include <linux/firewire.h>
      9#include <linux/export.h>
     10#include <linux/slab.h>
     11#include "packets-buffer.h"
     12
     13/**
     14 * iso_packets_buffer_init - allocates the memory for packets
     15 * @b: the buffer structure to initialize
     16 * @unit: the device at the other end of the stream
     17 * @count: the number of packets
     18 * @packet_size: the (maximum) size of a packet, in bytes
     19 * @direction: %DMA_TO_DEVICE or %DMA_FROM_DEVICE
     20 */
     21int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit,
     22			    unsigned int count, unsigned int packet_size,
     23			    enum dma_data_direction direction)
     24{
     25	unsigned int packets_per_page, pages;
     26	unsigned int i, page_index, offset_in_page;
     27	void *p;
     28	int err;
     29
     30	b->packets = kmalloc_array(count, sizeof(*b->packets), GFP_KERNEL);
     31	if (!b->packets) {
     32		err = -ENOMEM;
     33		goto error;
     34	}
     35
     36	packet_size = L1_CACHE_ALIGN(packet_size);
     37	packets_per_page = PAGE_SIZE / packet_size;
     38	if (WARN_ON(!packets_per_page)) {
     39		err = -EINVAL;
     40		goto err_packets;
     41	}
     42	pages = DIV_ROUND_UP(count, packets_per_page);
     43
     44	err = fw_iso_buffer_init(&b->iso_buffer, fw_parent_device(unit)->card,
     45				 pages, direction);
     46	if (err < 0)
     47		goto err_packets;
     48
     49	for (i = 0; i < count; ++i) {
     50		page_index = i / packets_per_page;
     51		p = page_address(b->iso_buffer.pages[page_index]);
     52		offset_in_page = (i % packets_per_page) * packet_size;
     53		b->packets[i].buffer = p + offset_in_page;
     54		b->packets[i].offset = page_index * PAGE_SIZE + offset_in_page;
     55	}
     56
     57	return 0;
     58
     59err_packets:
     60	kfree(b->packets);
     61error:
     62	return err;
     63}
     64EXPORT_SYMBOL(iso_packets_buffer_init);
     65
     66/**
     67 * iso_packets_buffer_destroy - frees packet buffer resources
     68 * @b: the buffer structure to free
     69 * @unit: the device at the other end of the stream
     70 */
     71void iso_packets_buffer_destroy(struct iso_packets_buffer *b,
     72				struct fw_unit *unit)
     73{
     74	fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card);
     75	kfree(b->packets);
     76}
     77EXPORT_SYMBOL(iso_packets_buffer_destroy);