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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msu-sink.c (2413B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * An example software sink buffer for Intel TH MSU.
      4 *
      5 * Copyright (C) 2019 Intel Corporation.
      6 */
      7
      8#include <linux/intel_th.h>
      9#include <linux/module.h>
     10#include <linux/slab.h>
     11#include <linux/device.h>
     12#include <linux/dma-mapping.h>
     13
     14#define MAX_SGTS 16
     15
     16struct msu_sink_private {
     17	struct device	*dev;
     18	struct sg_table **sgts;
     19	unsigned int	nr_sgts;
     20};
     21
     22static void *msu_sink_assign(struct device *dev, int *mode)
     23{
     24	struct msu_sink_private *priv;
     25
     26	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
     27	if (!priv)
     28		return NULL;
     29
     30	priv->sgts = kcalloc(MAX_SGTS, sizeof(void *), GFP_KERNEL);
     31	if (!priv->sgts) {
     32		kfree(priv);
     33		return NULL;
     34	}
     35
     36	priv->dev = dev;
     37	*mode = MSC_MODE_MULTI;
     38
     39	return priv;
     40}
     41
     42static void msu_sink_unassign(void *data)
     43{
     44	struct msu_sink_private *priv = data;
     45
     46	kfree(priv->sgts);
     47	kfree(priv);
     48}
     49
     50/* See also: msc.c: __msc_buffer_win_alloc() */
     51static int msu_sink_alloc_window(void *data, struct sg_table **sgt, size_t size)
     52{
     53	struct msu_sink_private *priv = data;
     54	unsigned int nents;
     55	struct scatterlist *sg_ptr;
     56	void *block;
     57	int ret, i;
     58
     59	if (priv->nr_sgts == MAX_SGTS)
     60		return -ENOMEM;
     61
     62	nents = DIV_ROUND_UP(size, PAGE_SIZE);
     63
     64	ret = sg_alloc_table(*sgt, nents, GFP_KERNEL);
     65	if (ret)
     66		return -ENOMEM;
     67
     68	priv->sgts[priv->nr_sgts++] = *sgt;
     69
     70	for_each_sg((*sgt)->sgl, sg_ptr, nents, i) {
     71		block = dma_alloc_coherent(priv->dev->parent->parent,
     72					   PAGE_SIZE, &sg_dma_address(sg_ptr),
     73					   GFP_KERNEL);
     74		sg_set_buf(sg_ptr, block, PAGE_SIZE);
     75	}
     76
     77	return nents;
     78}
     79
     80/* See also: msc.c: __msc_buffer_win_free() */
     81static void msu_sink_free_window(void *data, struct sg_table *sgt)
     82{
     83	struct msu_sink_private *priv = data;
     84	struct scatterlist *sg_ptr;
     85	int i;
     86
     87	for_each_sg(sgt->sgl, sg_ptr, sgt->nents, i) {
     88		dma_free_coherent(priv->dev->parent->parent, PAGE_SIZE,
     89				  sg_virt(sg_ptr), sg_dma_address(sg_ptr));
     90	}
     91
     92	sg_free_table(sgt);
     93	priv->nr_sgts--;
     94}
     95
     96static int msu_sink_ready(void *data, struct sg_table *sgt, size_t bytes)
     97{
     98	struct msu_sink_private *priv = data;
     99
    100	intel_th_msc_window_unlock(priv->dev, sgt);
    101
    102	return 0;
    103}
    104
    105static const struct msu_buffer sink_mbuf = {
    106	.name		= "sink",
    107	.assign		= msu_sink_assign,
    108	.unassign	= msu_sink_unassign,
    109	.alloc_window	= msu_sink_alloc_window,
    110	.free_window	= msu_sink_free_window,
    111	.ready		= msu_sink_ready,
    112};
    113
    114module_intel_th_msu_buffer(sink_mbuf);
    115
    116MODULE_LICENSE("GPL v2");