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

userimask.c (2093B)

      1/*
      2 * Support for hardware-assisted userspace interrupt masking.
      3 *
      4 * Copyright (C) 2010  Paul Mundt
      5 *
      6 * This file is subject to the terms and conditions of the GNU General Public
      7 * License.  See the file "COPYING" in the main directory of this archive
      8 * for more details.
      9 */
     10#define pr_fmt(fmt) "intc: " fmt
     11
     12#include <linux/errno.h>
     13#include <linux/device.h>
     14#include <linux/init.h>
     15#include <linux/io.h>
     16#include <linux/stat.h>
     17#include <linux/sizes.h>
     18#include "internals.h"
     19
     20static void __iomem *uimask;
     21
     22static ssize_t
     23show_intc_userimask(struct device *dev,
     24		    struct device_attribute *attr, char *buf)
     25{
     26	return sprintf(buf, "%d\n", (__raw_readl(uimask) >> 4) & 0xf);
     27}
     28
     29static ssize_t
     30store_intc_userimask(struct device *dev,
     31		     struct device_attribute *attr,
     32		     const char *buf, size_t count)
     33{
     34	unsigned long level;
     35
     36	level = simple_strtoul(buf, NULL, 10);
     37
     38	/*
     39	 * Minimal acceptable IRQ levels are in the 2 - 16 range, but
     40	 * these are chomped so as to not interfere with normal IRQs.
     41	 *
     42	 * Level 1 is a special case on some CPUs in that it's not
     43	 * directly settable, but given that USERIMASK cuts off below a
     44	 * certain level, we don't care about this limitation here.
     45	 * Level 0 on the other hand equates to user masking disabled.
     46	 *
     47	 * We use the default priority level as a cut off so that only
     48	 * special case opt-in IRQs can be mangled.
     49	 */
     50	if (level >= intc_get_dfl_prio_level())
     51		return -EINVAL;
     52
     53	__raw_writel(0xa5 << 24 | level << 4, uimask);
     54
     55	return count;
     56}
     57
     58static DEVICE_ATTR(userimask, S_IRUSR | S_IWUSR,
     59		   show_intc_userimask, store_intc_userimask);
     60
     61
     62static int __init userimask_sysdev_init(void)
     63{
     64	if (unlikely(!uimask))
     65		return -ENXIO;
     66
     67	return device_create_file(intc_subsys.dev_root, &dev_attr_userimask);
     68}
     69late_initcall(userimask_sysdev_init);
     70
     71int register_intc_userimask(unsigned long addr)
     72{
     73	if (unlikely(uimask))
     74		return -EBUSY;
     75
     76	uimask = ioremap(addr, SZ_4K);
     77	if (unlikely(!uimask))
     78		return -ENOMEM;
     79
     80	pr_info("userimask support registered for levels 0 -> %d\n",
     81		intc_get_dfl_prio_level() - 1);
     82
     83	return 0;
     84}