From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- kernel/trace/pid_list.h | 88 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 kernel/trace/pid_list.h (limited to 'kernel/trace/pid_list.h') diff --git a/kernel/trace/pid_list.h b/kernel/trace/pid_list.h new file mode 100644 index 000000000..62e73f1ac --- /dev/null +++ b/kernel/trace/pid_list.h @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* Do not include this file directly. */ + +#ifndef _TRACE_INTERNAL_PID_LIST_H +#define _TRACE_INTERNAL_PID_LIST_H + +/* + * In order to keep track of what pids to trace, a tree is created much + * like page tables are used. This creates a sparse bit map, where + * the tree is filled in when needed. A PID is at most 30 bits (see + * linux/thread.h), and is broken up into 3 sections based on the bit map + * of the bits. The 8 MSB is the "upper1" section. The next 8 MSB is the + * "upper2" section and the 14 LSB is the "lower" section. + * + * A trace_pid_list structure holds the "upper1" section, in an + * array of 256 pointers (1 or 2K in size) to "upper_chunk" unions, where + * each has an array of 256 pointers (1 or 2K in size) to the "lower_chunk" + * structures, where each has an array of size 2K bytes representing a bitmask + * of the 14 LSB of the PID (256 * 8 = 2048) + * + * When a trace_pid_list is allocated, it includes the 256 pointer array + * of the upper1 unions. Then a "cache" of upper and lower is allocated + * where these will be assigned as needed. + * + * When a bit is set in the pid_list bitmask, the pid to use has + * the 8 MSB masked, and this is used to index the array in the + * pid_list to find the next upper union. If the element is NULL, + * then one is retrieved from the upper_list cache. If none is + * available, then -ENOMEM is returned. + * + * The next 8 MSB is used to index into the "upper2" section. If this + * element is NULL, then it is retrieved from the lower_list cache. + * Again, if one is not available -ENOMEM is returned. + * + * Finally the 14 LSB of the PID is used to set the bit in the 16384 + * bitmask (made up of 2K bytes). + * + * When the second upper section or the lower section has their last + * bit cleared, they are added back to the free list to be reused + * when needed. + */ + +#define UPPER_BITS 8 +#define UPPER_MAX (1 << UPPER_BITS) +#define UPPER1_SIZE (1 << UPPER_BITS) +#define UPPER2_SIZE (1 << UPPER_BITS) + +#define LOWER_BITS 14 +#define LOWER_MAX (1 << LOWER_BITS) +#define LOWER_SIZE (LOWER_MAX / BITS_PER_LONG) + +#define UPPER1_SHIFT (LOWER_BITS + UPPER_BITS) +#define UPPER2_SHIFT LOWER_BITS +#define LOWER_MASK (LOWER_MAX - 1) + +#define UPPER_MASK (UPPER_MAX - 1) + +/* According to linux/thread.h pids can not be bigger than or equal to 1 << 30 */ +#define MAX_PID (1 << 30) + +/* Just keep 6 chunks of both upper and lower in the cache on alloc */ +#define CHUNK_ALLOC 6 + +/* Have 2 chunks free, trigger a refill of the cache */ +#define CHUNK_REALLOC 2 + +union lower_chunk { + union lower_chunk *next; + unsigned long data[LOWER_SIZE]; // 2K in size +}; + +union upper_chunk { + union upper_chunk *next; + union lower_chunk *data[UPPER2_SIZE]; // 1 or 2K in size +}; + +struct trace_pid_list { + raw_spinlock_t lock; + struct irq_work refill_irqwork; + union upper_chunk *upper[UPPER1_SIZE]; // 1 or 2K in size + union upper_chunk *upper_list; + union lower_chunk *lower_list; + int free_upper_chunks; + int free_lower_chunks; +}; + +#endif /* _TRACE_INTERNAL_PID_LIST_H */ -- cgit v1.2.3