/*
* Copyright (C) 2021 VMware Inc, Steven Rostedt <rostedt@goodmis.org>
*/
-#include <linux/vmalloc.h>
+#include <linux/spinlock.h>
+#include <linux/irq_work.h>
#include <linux/slab.h>
#include "trace.h"
+/* See pid_list.h for details */
+
+static inline union lower_chunk *get_lower_chunk(struct trace_pid_list *pid_list)
+{
+ union lower_chunk *chunk;
+
+ lockdep_assert_held(&pid_list->lock);
+
+ if (!pid_list->lower_list)
+ return NULL;
+
+ chunk = pid_list->lower_list;
+ pid_list->lower_list = chunk->next;
+ pid_list->free_lower_chunks--;
+ WARN_ON_ONCE(pid_list->free_lower_chunks < 0);
+ chunk->next = NULL;
+ /*
+ * If a refill needs to happen, it can not happen here
+ * as the scheduler run queue locks are held.
+ */
+ if (pid_list->free_lower_chunks <= CHUNK_REALLOC)
+ irq_work_queue(&pid_list->refill_irqwork);
+
+ return chunk;
+}
+
+static inline union upper_chunk *get_upper_chunk(struct trace_pid_list *pid_list)
+{
+ union upper_chunk *chunk;
+
+ lockdep_assert_held(&pid_list->lock);
+
+ if (!pid_list->upper_list)
+ return NULL;
+
+ chunk = pid_list->upper_list;
+ pid_list->upper_list = chunk->next;
+ pid_list->free_upper_chunks--;
+ WARN_ON_ONCE(pid_list->free_upper_chunks < 0);
+ chunk->next = NULL;
+ /*
+ * If a refill needs to happen, it can not happen here
+ * as the scheduler run queue locks are held.
+ */
+ if (pid_list->free_upper_chunks <= CHUNK_REALLOC)
+ irq_work_queue(&pid_list->refill_irqwork);
+
+ return chunk;
+}
+
+static inline void put_lower_chunk(struct trace_pid_list *pid_list,
+ union lower_chunk *chunk)
+{
+ lockdep_assert_held(&pid_list->lock);
+
+ chunk->next = pid_list->lower_list;
+ pid_list->lower_list = chunk;
+ pid_list->free_lower_chunks++;
+}
+
+static inline void put_upper_chunk(struct trace_pid_list *pid_list,
+ union upper_chunk *chunk)
+{
+ lockdep_assert_held(&pid_list->lock);
+
+ chunk->next = pid_list->upper_list;
+ pid_list->upper_list = chunk;
+ pid_list->free_upper_chunks++;
+}
+
+static inline bool upper_empty(union upper_chunk *chunk)
+{
+ /*
+ * If chunk->data has no lower chunks, it will be the same
+ * as a zeroed bitmask. Use find_first_bit() to test it
+ * and if it doesn't find any bits set, then the array
+ * is empty.
+ */
+ int bit = find_first_bit((unsigned long *)chunk->data,
+ sizeof(chunk->data) * 8);
+ return bit >= sizeof(chunk->data) * 8;
+}
+
+static inline int pid_split(unsigned int pid, unsigned int *upper1,
+ unsigned int *upper2, unsigned int *lower)
+{
+ /* MAX_PID should cover all pids */
+ BUILD_BUG_ON(MAX_PID < PID_MAX_LIMIT);
+
+ /* In case a bad pid is passed in, then fail */
+ if (unlikely(pid >= MAX_PID))
+ return -1;
+
+ *upper1 = (pid >> UPPER1_SHIFT) & UPPER_MASK;
+ *upper2 = (pid >> UPPER2_SHIFT) & UPPER_MASK;
+ *lower = pid & LOWER_MASK;
+
+ return 0;
+}
+
+static inline unsigned int pid_join(unsigned int upper1,
+ unsigned int upper2, unsigned int lower)
+{
+ return ((upper1 & UPPER_MASK) << UPPER1_SHIFT) |
+ ((upper2 & UPPER_MASK) << UPPER2_SHIFT) |
+ (lower & LOWER_MASK);
+}
+
/**
* trace_pid_list_is_set - test if the pid is set in the list
* @pid_list: The pid list to test
*/
bool trace_pid_list_is_set(struct trace_pid_list *pid_list, unsigned int pid)
{
- /*
- * If pid_max changed after filtered_pids was created, we
- * by default ignore all pids greater than the previous pid_max.
- */
- if (pid >= pid_list->pid_max)
+ union upper_chunk *upper_chunk;
+ union lower_chunk *lower_chunk;
+ unsigned long flags;
+ unsigned int upper1;
+ unsigned int upper2;
+ unsigned int lower;
+ bool ret = false;
+
+ if (!pid_list)
return false;
- return test_bit(pid, pid_list->pids);
+ if (pid_split(pid, &upper1, &upper2, &lower) < 0)
+ return false;
+
+ raw_spin_lock_irqsave(&pid_list->lock, flags);
+ upper_chunk = pid_list->upper[upper1];
+ if (upper_chunk) {
+ lower_chunk = upper_chunk->data[upper2];
+ if (lower_chunk)
+ ret = test_bit(lower, lower_chunk->data);
+ }
+ raw_spin_unlock_irqrestore(&pid_list->lock, flags);
+
+ return ret;
}
/**
*/
int trace_pid_list_set(struct trace_pid_list *pid_list, unsigned int pid)
{
- /* Sorry, but we don't support pid_max changing after setting */
- if (pid >= pid_list->pid_max)
- return -EINVAL;
+ union upper_chunk *upper_chunk;
+ union lower_chunk *lower_chunk;
+ unsigned long flags;
+ unsigned int upper1;
+ unsigned int upper2;
+ unsigned int lower;
+ int ret;
- set_bit(pid, pid_list->pids);
+ if (!pid_list)
+ return -ENODEV;
- return 0;
+ if (pid_split(pid, &upper1, &upper2, &lower) < 0)
+ return -EINVAL;
+
+ raw_spin_lock_irqsave(&pid_list->lock, flags);
+ upper_chunk = pid_list->upper[upper1];
+ if (!upper_chunk) {
+ upper_chunk = get_upper_chunk(pid_list);
+ if (!upper_chunk) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ pid_list->upper[upper1] = upper_chunk;
+ }
+ lower_chunk = upper_chunk->data[upper2];
+ if (!lower_chunk) {
+ lower_chunk = get_lower_chunk(pid_list);
+ if (!lower_chunk) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ upper_chunk->data[upper2] = lower_chunk;
+ }
+ set_bit(lower, lower_chunk->data);
+ ret = 0;
+ out:
+ raw_spin_unlock_irqrestore(&pid_list->lock, flags);
+ return ret;
}
/**
*/
int trace_pid_list_clear(struct trace_pid_list *pid_list, unsigned int pid)
{
- /* Sorry, but we don't support pid_max changing after setting */
- if (pid >= pid_list->pid_max)
+ union upper_chunk *upper_chunk;
+ union lower_chunk *lower_chunk;
+ unsigned long flags;
+ unsigned int upper1;
+ unsigned int upper2;
+ unsigned int lower;
+
+ if (!pid_list)
+ return -ENODEV;
+
+ if (pid_split(pid, &upper1, &upper2, &lower) < 0)
return -EINVAL;
- clear_bit(pid, pid_list->pids);
+ raw_spin_lock_irqsave(&pid_list->lock, flags);
+ upper_chunk = pid_list->upper[upper1];
+ if (!upper_chunk)
+ goto out;
+ lower_chunk = upper_chunk->data[upper2];
+ if (!lower_chunk)
+ goto out;
+
+ clear_bit(lower, lower_chunk->data);
+
+ /* if there's no more bits set, add it to the free list */
+ if (find_first_bit(lower_chunk->data, LOWER_MAX) >= LOWER_MAX) {
+ put_lower_chunk(pid_list, lower_chunk);
+ upper_chunk->data[upper2] = NULL;
+ if (upper_empty(upper_chunk)) {
+ put_upper_chunk(pid_list, upper_chunk);
+ pid_list->upper[upper1] = NULL;
+ }
+ }
+ out:
+ raw_spin_unlock_irqrestore(&pid_list->lock, flags);
return 0;
}
int trace_pid_list_next(struct trace_pid_list *pid_list, unsigned int pid,
unsigned int *next)
{
- pid = find_next_bit(pid_list->pids, pid_list->pid_max, pid);
+ union upper_chunk *upper_chunk;
+ union lower_chunk *lower_chunk;
+ unsigned long flags;
+ unsigned int upper1;
+ unsigned int upper2;
+ unsigned int lower;
+
+ if (!pid_list)
+ return -ENODEV;
+
+ if (pid_split(pid, &upper1, &upper2, &lower) < 0)
+ return -EINVAL;
- if (pid < pid_list->pid_max) {
- *next = pid;
- return 0;
+ raw_spin_lock_irqsave(&pid_list->lock, flags);
+ for (; upper1 <= UPPER_MASK; upper1++, upper2 = 0) {
+ upper_chunk = pid_list->upper[upper1];
+
+ if (!upper_chunk)
+ continue;
+
+ for (; upper2 <= UPPER_MASK; upper2++, lower = 0) {
+ lower_chunk = upper_chunk->data[upper2];
+ if (!lower_chunk)
+ continue;
+
+ lower = find_next_bit(lower_chunk->data, LOWER_MAX,
+ lower);
+ if (lower < LOWER_MAX)
+ goto found;
+ }
}
- return -1;
+
+ found:
+ raw_spin_unlock_irqrestore(&pid_list->lock, flags);
+ if (upper1 > UPPER_MASK)
+ return -1;
+
+ *next = pid_join(upper1, upper2, lower);
+ return 0;
}
/**
*/
int trace_pid_list_first(struct trace_pid_list *pid_list, unsigned int *pid)
{
- unsigned int first;
+ return trace_pid_list_next(pid_list, 0, pid);
+}
+
+static void pid_list_refill_irq(struct irq_work *iwork)
+{
+ struct trace_pid_list *pid_list = container_of(iwork, struct trace_pid_list,
+ refill_irqwork);
+ union upper_chunk *upper;
+ union lower_chunk *lower;
+ union upper_chunk **upper_next = &upper;
+ union lower_chunk **lower_next = &lower;
+ int upper_count;
+ int lower_count;
+ int ucnt = 0;
+ int lcnt = 0;
- first = find_first_bit(pid_list->pids, pid_list->pid_max);
+ again:
+ raw_spin_lock(&pid_list->lock);
+ upper_count = CHUNK_ALLOC - pid_list->free_upper_chunks;
+ lower_count = CHUNK_ALLOC - pid_list->free_lower_chunks;
+ raw_spin_unlock(&pid_list->lock);
+
+ if (upper_count <= 0 && lower_count <= 0)
+ return;
- if (first < pid_list->pid_max) {
- *pid = first;
- return 0;
+ while (upper_count-- > 0) {
+ union upper_chunk *chunk;
+
+ chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
+ if (!chunk)
+ break;
+ *upper_next = chunk;
+ upper_next = &chunk->next;
+ ucnt++;
}
- return -1;
+
+ while (lower_count-- > 0) {
+ union lower_chunk *chunk;
+
+ chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
+ if (!chunk)
+ break;
+ *lower_next = chunk;
+ lower_next = &chunk->next;
+ lcnt++;
+ }
+
+ raw_spin_lock(&pid_list->lock);
+ if (upper) {
+ *upper_next = pid_list->upper_list;
+ pid_list->upper_list = upper;
+ pid_list->free_upper_chunks += ucnt;
+ }
+ if (lower) {
+ *lower_next = pid_list->lower_list;
+ pid_list->lower_list = lower;
+ pid_list->free_lower_chunks += lcnt;
+ }
+ raw_spin_unlock(&pid_list->lock);
+
+ /*
+ * On success of allocating all the chunks, both counters
+ * will be less than zero. If they are not, then an allocation
+ * failed, and we should not try again.
+ */
+ if (upper_count >= 0 || lower_count >= 0)
+ return;
+ /*
+ * When the locks were released, free chunks could have
+ * been used and allocation needs to be done again. Might as
+ * well allocate it now.
+ */
+ goto again;
}
/**
struct trace_pid_list *trace_pid_list_alloc(void)
{
struct trace_pid_list *pid_list;
+ int i;
+
+ /* According to linux/thread.h, pids can be no bigger that 30 bits */
+ WARN_ON_ONCE(pid_max > (1 << 30));
- pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL);
+ pid_list = kzalloc(sizeof(*pid_list), GFP_KERNEL);
if (!pid_list)
return NULL;
- pid_list->pid_max = READ_ONCE(pid_max);
+ init_irq_work(&pid_list->refill_irqwork, pid_list_refill_irq);
- pid_list->pids = vzalloc((pid_list->pid_max + 7) >> 3);
- if (!pid_list->pids) {
- kfree(pid_list);
- return NULL;
+ raw_spin_lock_init(&pid_list->lock);
+
+ for (i = 0; i < CHUNK_ALLOC; i++) {
+ union upper_chunk *chunk;
+
+ chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
+ if (!chunk)
+ break;
+ chunk->next = pid_list->upper_list;
+ pid_list->upper_list = chunk;
+ pid_list->free_upper_chunks++;
}
+
+ for (i = 0; i < CHUNK_ALLOC; i++) {
+ union lower_chunk *chunk;
+
+ chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
+ if (!chunk)
+ break;
+ chunk->next = pid_list->lower_list;
+ pid_list->lower_list = chunk;
+ pid_list->free_lower_chunks++;
+ }
+
return pid_list;
}
*/
void trace_pid_list_free(struct trace_pid_list *pid_list)
{
+ union upper_chunk *upper;
+ union lower_chunk *lower;
+ int i, j;
+
if (!pid_list)
return;
- vfree(pid_list->pids);
+ irq_work_sync(&pid_list->refill_irqwork);
+
+ while (pid_list->lower_list) {
+ union lower_chunk *chunk;
+
+ chunk = pid_list->lower_list;
+ pid_list->lower_list = pid_list->lower_list->next;
+ kfree(chunk);
+ }
+
+ while (pid_list->upper_list) {
+ union upper_chunk *chunk;
+
+ chunk = pid_list->upper_list;
+ pid_list->upper_list = pid_list->upper_list->next;
+ kfree(chunk);
+ }
+
+ for (i = 0; i < UPPER1_SIZE; i++) {
+ upper = pid_list->upper[i];
+ if (upper) {
+ for (j = 0; j < UPPER2_SIZE; j++) {
+ lower = upper->data[j];
+ kfree(lower);
+ }
+ kfree(upper);
+ }
+ }
kfree(pid_list);
}
#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 {
- int pid_max;
- unsigned long *pids;
+ 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 */
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