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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pid_list.h (3053B)

      1// SPDX-License-Identifier: GPL-2.0
      2
      3/* Do not include this file directly. */
      4
      5#ifndef _TRACE_INTERNAL_PID_LIST_H
      6#define _TRACE_INTERNAL_PID_LIST_H
      7
      8/*
      9 * In order to keep track of what pids to trace, a tree is created much
     10 * like page tables are used. This creates a sparse bit map, where
     11 * the tree is filled in when needed. A PID is at most 30 bits (see
     12 * linux/thread.h), and is broken up into 3 sections based on the bit map
     13 * of the bits. The 8 MSB is the "upper1" section. The next 8 MSB is the
     14 * "upper2" section and the 14 LSB is the "lower" section.
     15 *
     16 * A trace_pid_list structure holds the "upper1" section, in an
     17 * array of 256 pointers (1 or 2K in size) to "upper_chunk" unions, where
     18 * each has an array of 256 pointers (1 or 2K in size) to the "lower_chunk"
     19 * structures, where each has an array of size 2K bytes representing a bitmask
     20 * of the 14 LSB of the PID (256 * 8 = 2048)
     21 *
     22 * When a trace_pid_list is allocated, it includes the 256 pointer array
     23 * of the upper1 unions. Then a "cache" of upper and lower is allocated
     24 * where these will be assigned as needed.
     25 *
     26 * When a bit is set in the pid_list bitmask, the pid to use has
     27 * the 8 MSB masked, and this is used to index the array in the
     28 * pid_list to find the next upper union. If the element is NULL,
     29 * then one is retrieved from the upper_list cache. If none is
     30 * available, then -ENOMEM is returned.
     31 *
     32 * The next 8 MSB is used to index into the "upper2" section. If this
     33 * element is NULL, then it is retrieved from the lower_list cache.
     34 * Again, if one is not available -ENOMEM is returned.
     35 *
     36 * Finally the 14 LSB of the PID is used to set the bit in the 16384
     37 * bitmask (made up of 2K bytes).
     38 *
     39 * When the second upper section or the lower section has their last
     40 * bit cleared, they are added back to the free list to be reused
     41 * when needed.
     42 */
     43
     44#define UPPER_BITS	8
     45#define UPPER_MAX	(1 << UPPER_BITS)
     46#define UPPER1_SIZE	(1 << UPPER_BITS)
     47#define UPPER2_SIZE	(1 << UPPER_BITS)
     48
     49#define LOWER_BITS	14
     50#define LOWER_MAX	(1 << LOWER_BITS)
     51#define LOWER_SIZE	(LOWER_MAX / BITS_PER_LONG)
     52
     53#define UPPER1_SHIFT	(LOWER_BITS + UPPER_BITS)
     54#define UPPER2_SHIFT	LOWER_BITS
     55#define LOWER_MASK	(LOWER_MAX - 1)
     56
     57#define UPPER_MASK	(UPPER_MAX - 1)
     58
     59/* According to linux/thread.h pids can not be bigger than or equal to 1 << 30 */
     60#define MAX_PID		(1 << 30)
     61
     62/* Just keep 6 chunks of both upper and lower in the cache on alloc */
     63#define CHUNK_ALLOC 6
     64
     65/* Have 2 chunks free, trigger a refill of the cache */
     66#define CHUNK_REALLOC 2
     67
     68union lower_chunk {
     69	union lower_chunk		*next;
     70	unsigned long			data[LOWER_SIZE]; // 2K in size
     71};
     72
     73union upper_chunk {
     74	union upper_chunk		*next;
     75	union lower_chunk		*data[UPPER2_SIZE]; // 1 or 2K in size
     76};
     77
     78struct trace_pid_list {
     79	raw_spinlock_t			lock;
     80	struct irq_work			refill_irqwork;
     81	union upper_chunk		*upper[UPPER1_SIZE]; // 1 or 2K in size
     82	union upper_chunk		*upper_list;
     83	union lower_chunk		*lower_list;
     84	int				free_upper_chunks;
     85	int				free_lower_chunks;
     86};
     87
     88#endif /* _TRACE_INTERNAL_PID_LIST_H */