/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_RING_BUFFER_H
#define _LINUX_RING_BUFFER_H

#include <linux/mm.h>
#include <linux/poll.h>
#include <linux/seq_file.h>

#include <asm/local.h>

#include <uapi/linux/trace_mmap.h>

struct trace_buffer;
struct ring_buffer_iter;

/*
 * Don't refer to this struct directly, use functions below.
 */
struct ring_buffer_event {
	u32		type_len:5, time_delta:27;

	u32		array[];
};

#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array))

/**
 * enum ring_buffer_type - internal ring buffer types
 *
 * @RINGBUF_TYPE_PADDING:	Left over page padding or discarded event
 *				 If time_delta is 0:
 *				  array is ignored
 *				  size is variable depending on how much
 *				  padding is needed
 *				 If time_delta is non zero:
 *				  array[0] holds the actual length
 *				  size = 4 + length (bytes)
 *
 * @RINGBUF_TYPE_TIME_EXTEND:	Extend the time delta
 *				 array[0] = time delta (28 .. 59)
 *				 size = 8 bytes
 *
 * @RINGBUF_TYPE_TIME_STAMP:	Absolute timestamp
 *				 Same format as TIME_EXTEND except that the
 *				 value is an absolute timestamp, not a delta
 *				 event.time_delta contains bottom 27 bits
 *				 array[0] = top (28 .. 59) bits
 *				 size = 8 bytes
 *
 * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
 *				Data record
 *				 If type_len is zero:
 *				  array[0] holds the actual length
 *				  array[1..(length+3)/4] holds data
 *				  size = 4 + length (bytes)
 *				 else
 *				  length = type_len << 2
 *				  array[0..(length+3)/4-1] holds data
 *				  size = 4 + length (bytes)
 */
enum ring_buffer_type {
	RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
	RINGBUF_TYPE_PADDING,
	RINGBUF_TYPE_TIME_EXTEND,
	RINGBUF_TYPE_TIME_STAMP,
};

#define TS_SHIFT        27
#define TS_MASK         ((1ULL << TS_SHIFT) - 1)
#define TS_DELTA_TEST   (~TS_MASK)

/*
 * We need to fit the time_stamp delta into 27 bits.
 */
static inline bool test_time_stamp(u64 delta)
{
	return !!(delta & TS_DELTA_TEST);
}

unsigned ring_buffer_event_length(struct ring_buffer_event *event);
void *ring_buffer_event_data(struct ring_buffer_event *event);
u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer,
				 struct ring_buffer_event *event);

#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data)

/* Max payload is BUF_PAGE_SIZE - header (8bytes) */
#define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2))

#define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE)

#define RB_ALIGNMENT		4U
#define RB_MAX_SMALL_DATA	(RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX)
#define RB_EVNT_MIN_SIZE	8U	/* two 32bit words */

#ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS
# define RB_FORCE_8BYTE_ALIGNMENT	0
# define RB_ARCH_ALIGNMENT		RB_ALIGNMENT
#else
# define RB_FORCE_8BYTE_ALIGNMENT	1
# define RB_ARCH_ALIGNMENT		8U
#endif

#define RB_ALIGN_DATA		__aligned(RB_ARCH_ALIGNMENT)

struct buffer_data_page {
	u64		 time_stamp;	/* page time stamp */
	local_t		 commit;	/* write committed index */
	unsigned char	 data[] RB_ALIGN_DATA;	/* data of buffer page */
};

/*
 * ring_buffer_discard_commit will remove an event that has not
 *   been committed yet. If this is used, then ring_buffer_unlock_commit
 *   must not be called on the discarded event. This function
 *   will try to remove the event from the ring buffer completely
 *   if another event has not been written after it.
 *
 * Example use:
 *
 *  if (some_condition)
 *    ring_buffer_discard_commit(buffer, event);
 *  else
 *    ring_buffer_unlock_commit(buffer, event);
 */
void ring_buffer_discard_commit(struct trace_buffer *buffer,
				struct ring_buffer_event *event);

struct ring_buffer_writer;

/*
 * size is in bytes for each per CPU buffer.
 */
struct trace_buffer *
__ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key,
		    struct ring_buffer_writer *writer);

/*
 * Because the ring buffer is generic, if other users of the ring buffer get
 * traced by ftrace, it can produce lockdep warnings. We need to keep each
 * ring buffer's lock class separate.
 */
#define ring_buffer_alloc(size, flags)				\
({								\
	static struct lock_class_key __key;			\
	__ring_buffer_alloc((size), (flags), &__key, NULL);	\
})

typedef bool (*ring_buffer_cond_fn)(void *data);
int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full);
__poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
			  struct file *filp, poll_table *poll_table, int full);
void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu);

#define RING_BUFFER_ALL_CPUS -1

void ring_buffer_free(struct trace_buffer *buffer);

int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu);

void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val);

struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer,
						   unsigned long length);
int ring_buffer_unlock_commit(struct trace_buffer *buffer);
int ring_buffer_write(struct trace_buffer *buffer,
		      unsigned long length, void *data);

void ring_buffer_nest_start(struct trace_buffer *buffer);
void ring_buffer_nest_end(struct trace_buffer *buffer);

struct ring_buffer_event *
ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
		 unsigned long *lost_events);
struct ring_buffer_event *
ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts,
		    unsigned long *lost_events);

struct ring_buffer_iter *
ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags);
void ring_buffer_read_prepare_sync(void);
void ring_buffer_read_start(struct ring_buffer_iter *iter);
void ring_buffer_read_finish(struct ring_buffer_iter *iter);

struct ring_buffer_event *
ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
void ring_buffer_iter_advance(struct ring_buffer_iter *iter);
void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);

unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);

void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu);
void ring_buffer_reset_online_cpus(struct trace_buffer *buffer);
void ring_buffer_reset(struct trace_buffer *buffer);

#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
			 struct trace_buffer *buffer_b, int cpu);
#else
static inline int
ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
		     struct trace_buffer *buffer_b, int cpu)
{
	return -ENODEV;
}
#endif

bool ring_buffer_empty(struct trace_buffer *buffer);
bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu);

void ring_buffer_record_disable(struct trace_buffer *buffer);
void ring_buffer_record_enable(struct trace_buffer *buffer);
void ring_buffer_record_off(struct trace_buffer *buffer);
void ring_buffer_record_on(struct trace_buffer *buffer);
bool ring_buffer_record_is_on(struct trace_buffer *buffer);
bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);
void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);
void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);

u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu);
unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu);
unsigned long ring_buffer_entries(struct trace_buffer *buffer);
unsigned long ring_buffer_overruns(struct trace_buffer *buffer);
unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu);
unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu);
unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu);
unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu);
unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu);

u64 ring_buffer_time_stamp(struct trace_buffer *buffer);
void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer,
				      int cpu, u64 *ts);
void ring_buffer_set_clock(struct trace_buffer *buffer,
			   u64 (*clock)(void));
void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs);
bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer);

size_t ring_buffer_nr_pages(struct trace_buffer *buffer, int cpu);
size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu);

void *ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu);
void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, void *data);
int ring_buffer_read_page(struct trace_buffer *buffer, void **data_page,
			  size_t len, int cpu, int full);

struct trace_seq;

int ring_buffer_print_entry_header(struct trace_seq *s);
int ring_buffer_print_page_header(struct trace_seq *s);

enum ring_buffer_flags {
	RB_FL_OVERWRITE		= 1 << 0,
};

#ifdef CONFIG_RING_BUFFER
int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
#else
#define trace_rb_cpu_prepare	NULL
#endif

int ring_buffer_map(struct trace_buffer *buffer, int cpu);
int ring_buffer_unmap(struct trace_buffer *buffer, int cpu);
struct page *ring_buffer_map_fault(struct trace_buffer *buffer, int cpu,
				   unsigned long pgoff);
int ring_buffer_map_get_reader_page(struct trace_buffer *buffer, int cpu);

struct rb_page_desc {
	int		cpu;
	int		nr_page_va; /* exclude the meta page */
	unsigned long	meta_va;
	unsigned long	page_va[];
};

struct trace_page_desc {
	int		nr_cpus;
	char		__data[]; /* list of rb_page_desc */
};

static inline
struct rb_page_desc *__next_rb_page_desc(struct rb_page_desc *pdesc)
{
	size_t len = struct_size(pdesc, page_va, pdesc->nr_page_va);

	return (struct rb_page_desc *)((void *)pdesc + len);
}

#define for_each_rb_page_desc(__pdesc, __cpu, __trace_pdesc)				\
	for (__pdesc = (struct rb_page_desc *)&((__trace_pdesc)->__data[0]), __cpu = 0;	\
	     __cpu < (__trace_pdesc)->nr_cpus;						\
	     __cpu++, __pdesc = __next_rb_page_desc(__pdesc))

static inline
struct rb_page_desc *rb_page_desc(struct trace_page_desc *trace_pdesc, int cpu)
{
	struct rb_page_desc *pdesc;
	int i;

	if (!trace_pdesc)
		return NULL;

	for_each_rb_page_desc(pdesc, i, trace_pdesc) {
		if (pdesc->cpu == cpu)
			return pdesc;
	}

	return NULL;
}

static inline
void *rb_page_desc_page(struct rb_page_desc *pdesc, int page_id)
{
	return page_id > pdesc->nr_page_va ? NULL : (void *)pdesc->page_va[page_id];
}

struct ring_buffer_writer {
	struct trace_page_desc	*pdesc;
	int (*get_reader_page)(int cpu);
};

int ring_buffer_poll_writer(struct trace_buffer *buffer, int cpu);

#define ring_buffer_reader(writer)				\
({								\
	static struct lock_class_key __key;			\
	__ring_buffer_alloc(0, RB_FL_OVERWRITE, &__key, writer);\
})
#endif /* _LINUX_RING_BUFFER_H */