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

map.c (3402B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 *  linux/drivers/base/map.c
      4 *
      5 * (C) Copyright Al Viro 2002,2003
      6 *
      7 * NOTE: data structure needs to be changed.  It works, but for large dev_t
      8 * it will be too slow.  It is isolated, though, so these changes will be
      9 * local to that file.
     10 */
     11
     12#include <linux/module.h>
     13#include <linux/slab.h>
     14#include <linux/mutex.h>
     15#include <linux/kdev_t.h>
     16#include <linux/kobject.h>
     17#include <linux/kobj_map.h>
     18
     19struct kobj_map {
     20	struct probe {
     21		struct probe *next;
     22		dev_t dev;
     23		unsigned long range;
     24		struct module *owner;
     25		kobj_probe_t *get;
     26		int (*lock)(dev_t, void *);
     27		void *data;
     28	} *probes[255];
     29	struct mutex *lock;
     30};
     31
     32int kobj_map(struct kobj_map *domain, dev_t dev, unsigned long range,
     33	     struct module *module, kobj_probe_t *probe,
     34	     int (*lock)(dev_t, void *), void *data)
     35{
     36	unsigned int n = MAJOR(dev + range - 1) - MAJOR(dev) + 1;
     37	unsigned int index = MAJOR(dev);
     38	unsigned int i;
     39	struct probe *p;
     40
     41	if (n > 255)
     42		n = 255;
     43
     44	p = kmalloc_array(n, sizeof(struct probe), GFP_KERNEL);
     45	if (p == NULL)
     46		return -ENOMEM;
     47
     48	for (i = 0; i < n; i++, p++) {
     49		p->owner = module;
     50		p->get = probe;
     51		p->lock = lock;
     52		p->dev = dev;
     53		p->range = range;
     54		p->data = data;
     55	}
     56	mutex_lock(domain->lock);
     57	for (i = 0, p -= n; i < n; i++, p++, index++) {
     58		struct probe **s = &domain->probes[index % 255];
     59		while (*s && (*s)->range < range)
     60			s = &(*s)->next;
     61		p->next = *s;
     62		*s = p;
     63	}
     64	mutex_unlock(domain->lock);
     65	return 0;
     66}
     67
     68void kobj_unmap(struct kobj_map *domain, dev_t dev, unsigned long range)
     69{
     70	unsigned int n = MAJOR(dev + range - 1) - MAJOR(dev) + 1;
     71	unsigned int index = MAJOR(dev);
     72	unsigned int i;
     73	struct probe *found = NULL;
     74
     75	if (n > 255)
     76		n = 255;
     77
     78	mutex_lock(domain->lock);
     79	for (i = 0; i < n; i++, index++) {
     80		struct probe **s;
     81		for (s = &domain->probes[index % 255]; *s; s = &(*s)->next) {
     82			struct probe *p = *s;
     83			if (p->dev == dev && p->range == range) {
     84				*s = p->next;
     85				if (!found)
     86					found = p;
     87				break;
     88			}
     89		}
     90	}
     91	mutex_unlock(domain->lock);
     92	kfree(found);
     93}
     94
     95struct kobject *kobj_lookup(struct kobj_map *domain, dev_t dev, int *index)
     96{
     97	struct kobject *kobj;
     98	struct probe *p;
     99	unsigned long best = ~0UL;
    100
    101retry:
    102	mutex_lock(domain->lock);
    103	for (p = domain->probes[MAJOR(dev) % 255]; p; p = p->next) {
    104		struct kobject *(*probe)(dev_t, int *, void *);
    105		struct module *owner;
    106		void *data;
    107
    108		if (p->dev > dev || p->dev + p->range - 1 < dev)
    109			continue;
    110		if (p->range - 1 >= best)
    111			break;
    112		if (!try_module_get(p->owner))
    113			continue;
    114		owner = p->owner;
    115		data = p->data;
    116		probe = p->get;
    117		best = p->range - 1;
    118		*index = dev - p->dev;
    119		if (p->lock && p->lock(dev, data) < 0) {
    120			module_put(owner);
    121			continue;
    122		}
    123		mutex_unlock(domain->lock);
    124		kobj = probe(dev, index, data);
    125		/* Currently ->owner protects _only_ ->probe() itself. */
    126		module_put(owner);
    127		if (kobj)
    128			return kobj;
    129		goto retry;
    130	}
    131	mutex_unlock(domain->lock);
    132	return NULL;
    133}
    134
    135struct kobj_map *kobj_map_init(kobj_probe_t *base_probe, struct mutex *lock)
    136{
    137	struct kobj_map *p = kmalloc(sizeof(struct kobj_map), GFP_KERNEL);
    138	struct probe *base = kzalloc(sizeof(*base), GFP_KERNEL);
    139	int i;
    140
    141	if ((p == NULL) || (base == NULL)) {
    142		kfree(p);
    143		kfree(base);
    144		return NULL;
    145	}
    146
    147	base->dev = 1;
    148	base->range = ~0;
    149	base->get = base_probe;
    150	for (i = 0; i < 255; i++)
    151		p->probes[i] = base;
    152	p->lock = lock;
    153	return p;
    154}