--- /dev/null
+/*
+ * Copyright (C) 2009, 2010 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License (not later!)
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "kbuffer.h"
+
+#define MISSING_EVENTS (1 << 31)
+#define MISSING_STORED (1 << 30)
+
+#define COMMIT_MASK ((1 << 27) - 1)
+
+enum {
+ KBUFFER_FL_HOST_BIG_ENDIAN = (1<<0),
+ KBUFFER_FL_BIG_ENDIAN = (1<<1),
+ KBUFFER_FL_LONG_8 = (1<<2),
+ KBUFFER_FL_OLD_FORMAT = (1<<3),
+};
+
+#define ENDIAN_MASK (KBUFFER_FL_HOST_BIG_ENDIAN | KBUFFER_FL_BIG_ENDIAN)
+
+/** kbuffer
+ * @timestamp - timestamp of current event
+ * @lost_events - # of lost events between this subbuffer and previous
+ * @flags - special flags of the kbuffer
+ * @subbuffer - pointer to the sub-buffer page
+ * @data - pointer to the start of data on the sub-buffer page
+ * @index - index from @data to the @curr event data
+ * @curr - offset from @data to the start of current event
+ * (includes metadata)
+ * @next - offset from @data to the start of next event
+ * @size - The size of data on @data
+ * @start - The offset from @subbuffer where @data lives
+ *
+ * @read_4 - Function to read 4 raw bytes (may swap)
+ * @read_8 - Function to read 8 raw bytes (may swap)
+ * @read_long - Function to read a long word (4 or 8 bytes with needed swap)
+ */
+struct kbuffer {
+ unsigned long long timestamp;
+ long long lost_events;
+ unsigned long flags;
+ void *subbuffer;
+ void *data;
+ unsigned int index;
+ unsigned int curr;
+ unsigned int next;
+ unsigned int size;
+ unsigned int start;
+
+ unsigned int (*read_4)(void *ptr);
+ unsigned long long (*read_8)(void *ptr);
+ unsigned long long (*read_long)(struct kbuffer *kbuf, void *ptr);
+ int (*next_event)(struct kbuffer *kbuf);
+};
+
+static void *zmalloc(size_t size)
+{
+ return calloc(1, size);
+}
+
+static int host_is_bigendian(void)
+{
+ unsigned char str[] = { 0x1, 0x2, 0x3, 0x4 };
+ unsigned int *ptr;
+
+ ptr = (unsigned int *)str;
+ return *ptr == 0x01020304;
+}
+
+static int do_swap(struct kbuffer *kbuf)
+{
+ return ((kbuf->flags & KBUFFER_FL_HOST_BIG_ENDIAN) + kbuf->flags) &
+ ENDIAN_MASK;
+}
+
+static unsigned long long __read_8(void *ptr)
+{
+ unsigned long long data = *(unsigned long long *)ptr;
+
+ return data;
+}
+
+static unsigned long long __read_8_sw(void *ptr)
+{
+ unsigned long long data = *(unsigned long long *)ptr;
+ unsigned long long swap;
+
+ swap = ((data & 0xffULL) << 56) |
+ ((data & (0xffULL << 8)) << 40) |
+ ((data & (0xffULL << 16)) << 24) |
+ ((data & (0xffULL << 24)) << 8) |
+ ((data & (0xffULL << 32)) >> 8) |
+ ((data & (0xffULL << 40)) >> 24) |
+ ((data & (0xffULL << 48)) >> 40) |
+ ((data & (0xffULL << 56)) >> 56);
+
+ return swap;
+}
+
+static unsigned int __read_4(void *ptr)
+{
+ unsigned int data = *(unsigned int *)ptr;
+
+ return data;
+}
+
+static unsigned int __read_4_sw(void *ptr)
+{
+ unsigned int data = *(unsigned int *)ptr;
+ unsigned int swap;
+
+ swap = ((data & 0xffULL) << 24) |
+ ((data & (0xffULL << 8)) << 8) |
+ ((data & (0xffULL << 16)) >> 8) |
+ ((data & (0xffULL << 24)) >> 24);
+
+ return swap;
+}
+
+static unsigned long long read_8(struct kbuffer *kbuf, void *ptr)
+{
+ return kbuf->read_8(ptr);
+}
+
+static unsigned int read_4(struct kbuffer *kbuf, void *ptr)
+{
+ return kbuf->read_4(ptr);
+}
+
+static unsigned long long __read_long_8(struct kbuffer *kbuf, void *ptr)
+{
+ return kbuf->read_8(ptr);
+}
+
+static unsigned long long __read_long_4(struct kbuffer *kbuf, void *ptr)
+{
+ return kbuf->read_4(ptr);
+}
+
+static unsigned long long read_long(struct kbuffer *kbuf, void *ptr)
+{
+ return kbuf->read_long(kbuf, ptr);
+}
+
+static int calc_index(struct kbuffer *kbuf, void *ptr)
+{
+ return (unsigned long)ptr - (unsigned long)kbuf->data;
+}
+
+static int __next_event(struct kbuffer *kbuf);
+
+/**
+ * kbuffer_alloc - allocat a new kbuffer
+ * @size; enum to denote size of word
+ * @endian: enum to denote endianness
+ *
+ * Allocates and returns a new kbuffer.
+ */
+struct kbuffer *
+kbuffer_alloc(enum kbuffer_long_size size, enum kbuffer_endian endian)
+{
+ struct kbuffer *kbuf;
+ int flags = 0;
+
+ switch (size) {
+ case KBUFFER_LSIZE_4:
+ break;
+ case KBUFFER_LSIZE_8:
+ flags |= KBUFFER_FL_LONG_8;
+ break;
+ default:
+ return NULL;
+ }
+
+ switch (endian) {
+ case KBUFFER_ENDIAN_LITTLE:
+ break;
+ case KBUFFER_ENDIAN_BIG:
+ flags |= KBUFFER_FL_BIG_ENDIAN;
+ break;
+ default:
+ return NULL;
+ }
+
+ kbuf = zmalloc(sizeof(*kbuf));
+ if (!kbuf)
+ return NULL;
+
+ kbuf->flags = flags;
+
+ if (host_is_bigendian())
+ kbuf->flags |= KBUFFER_FL_HOST_BIG_ENDIAN;
+
+ if (do_swap(kbuf)) {
+ kbuf->read_8 = __read_8_sw;
+ kbuf->read_4 = __read_4_sw;
+ } else {
+ kbuf->read_8 = __read_8;
+ kbuf->read_4 = __read_4;
+ }
+
+ if (kbuf->flags & KBUFFER_FL_LONG_8)
+ kbuf->read_long = __read_long_8;
+ else
+ kbuf->read_long = __read_long_4;
+
+ /* May be changed by kbuffer_set_old_format() */
+ kbuf->next_event = __next_event;
+
+ return kbuf;
+}
+
+/** kbuffer_free - free an allocated kbuffer
+ * @kbuf: The kbuffer to free
+ *
+ * Can take NULL as a parameter.
+ */
+void kbuffer_free(struct kbuffer *kbuf)
+{
+ free(kbuf);
+}
+
+static unsigned int type4host(struct kbuffer *kbuf,
+ unsigned int type_len_ts)
+{
+ if (kbuf->flags & KBUFFER_FL_BIG_ENDIAN)
+ return (type_len_ts >> 29) & 3;
+ else
+ return type_len_ts & 3;
+}
+
+static unsigned int len4host(struct kbuffer *kbuf,
+ unsigned int type_len_ts)
+{
+ if (kbuf->flags & KBUFFER_FL_BIG_ENDIAN)
+ return (type_len_ts >> 27) & 7;
+ else
+ return (type_len_ts >> 2) & 7;
+}
+
+static unsigned int type_len4host(struct kbuffer *kbuf,
+ unsigned int type_len_ts)
+{
+ if (kbuf->flags & KBUFFER_FL_BIG_ENDIAN)
+ return (type_len_ts >> 27) & ((1 << 5) - 1);
+ else
+ return type_len_ts & ((1 << 5) - 1);
+}
+
+static unsigned int ts4host(struct kbuffer *kbuf,
+ unsigned int type_len_ts)
+{
+ if (kbuf->flags & KBUFFER_FL_BIG_ENDIAN)
+ return type_len_ts & ((1 << 27) - 1);
+ else
+ return type_len_ts >> 5;
+}
+
+/*
+ * Linux 2.6.30 and earlier (not much ealier) had a different
+ * ring buffer format. It should be obsolete, but we handle it anyway.
+ */
+enum old_ring_buffer_type {
+ OLD_RINGBUF_TYPE_PADDING,
+ OLD_RINGBUF_TYPE_TIME_EXTEND,
+ OLD_RINGBUF_TYPE_TIME_STAMP,
+ OLD_RINGBUF_TYPE_DATA,
+};
+
+static unsigned int old_update_pointers(struct kbuffer *kbuf)
+{
+ unsigned long long extend;
+ unsigned int type_len_ts;
+ unsigned int type;
+ unsigned int len;
+ unsigned int delta;
+ unsigned int length;
+ void *ptr = kbuf->data + kbuf->curr;
+
+ type_len_ts = read_4(kbuf, ptr);
+ ptr += 4;
+
+ type = type4host(kbuf, type_len_ts);
+ len = len4host(kbuf, type_len_ts);
+ delta = ts4host(kbuf, type_len_ts);
+
+ switch (type) {
+ case OLD_RINGBUF_TYPE_PADDING:
+ kbuf->next = kbuf->size;
+ return 0;
+
+ case OLD_RINGBUF_TYPE_TIME_EXTEND:
+ extend = read_4(kbuf, ptr);
+ extend <<= TS_SHIFT;
+ extend += delta;
+ delta = extend;
+ ptr += 4;
+ break;
+
+ case OLD_RINGBUF_TYPE_TIME_STAMP:
+ /* should never happen! */
+ kbuf->curr = kbuf->size;
+ kbuf->next = kbuf->size;
+ kbuf->index = kbuf->size;
+ return -1;
+ default:
+ if (len)
+ length = len * 4;
+ else {
+ length = read_4(kbuf, ptr);
+ length -= 4;
+ ptr += 4;
+ }
+ break;
+ }
+
+ kbuf->timestamp += delta;
+ kbuf->index = calc_index(kbuf, ptr);
+ kbuf->next = kbuf->index + length;
+
+ return type;
+}
+
+static int __old_next_event(struct kbuffer *kbuf)
+{
+ int type;
+
+ do {
+ kbuf->curr = kbuf->next;
+ if (kbuf->next >= kbuf->size)
+ return -1;
+ type = old_update_pointers(kbuf);
+ } while (type == OLD_RINGBUF_TYPE_TIME_EXTEND || type == OLD_RINGBUF_TYPE_PADDING);
+
+ return 0;
+}
+
+static unsigned int
+translate_data(struct kbuffer *kbuf, void *data, void **rptr,
+ unsigned long long *delta, int *length)
+{
+ unsigned long long extend;
+ unsigned int type_len_ts;
+ unsigned int type_len;
+
+ type_len_ts = read_4(kbuf, data);
+ data += 4;
+
+ type_len = type_len4host(kbuf, type_len_ts);
+ *delta = ts4host(kbuf, type_len_ts);
+
+ switch (type_len) {
+ case KBUFFER_TYPE_PADDING:
+ *length = read_4(kbuf, data);
+ data += *length;
+ break;
+
+ case KBUFFER_TYPE_TIME_EXTEND:
+ extend = read_4(kbuf, data);
+ data += 4;
+ extend <<= TS_SHIFT;
+ extend += *delta;
+ *delta = extend;
+ *length = 0;
+ break;
+
+ case KBUFFER_TYPE_TIME_STAMP:
+ data += 12;
+ *length = 0;
+ break;
+ case 0:
+ *length = read_4(kbuf, data) - 4;
+ *length = (*length + 3) & ~3;
+ data += 4;
+ break;
+ default:
+ *length = type_len * 4;
+ break;
+ }
+
+ *rptr = data;
+
+ return type_len;
+}
+
+static unsigned int update_pointers(struct kbuffer *kbuf)
+{
+ unsigned long long delta;
+ unsigned int type_len;
+ int length;
+ void *ptr = kbuf->data + kbuf->curr;
+
+ type_len = translate_data(kbuf, ptr, &ptr, &delta, &length);
+
+ kbuf->timestamp += delta;
+ kbuf->index = calc_index(kbuf, ptr);
+ kbuf->next = kbuf->index + length;
+
+ return type_len;
+}
+
+/**
+ * kbuffer_translate_data - read raw data to get a record
+ * @swap: Set to 1 if bytes in words need to be swapped when read
+ * @data: The raw data to read
+ * @size: Address to store the size of the event data.
+ *
+ * Returns a pointer to the event data. To determine the entire
+ * record size (record metadata + data) just add the difference between
+ * @data and the returned value to @size.
+ */
+void *kbuffer_translate_data(int swap, void *data, unsigned int *size)
+{
+ unsigned long long delta;
+ struct kbuffer kbuf;
+ int type_len;
+ int length;
+ void *ptr;
+
+ if (swap) {
+ kbuf.read_8 = __read_8_sw;
+ kbuf.read_4 = __read_4_sw;
+ kbuf.flags = host_is_bigendian() ? 0 : KBUFFER_FL_BIG_ENDIAN;
+ } else {
+ kbuf.read_8 = __read_8;
+ kbuf.read_4 = __read_4;
+ kbuf.flags = host_is_bigendian() ? KBUFFER_FL_BIG_ENDIAN: 0;
+ }
+
+ type_len = translate_data(&kbuf, data, &ptr, &delta, &length);
+ switch (type_len) {
+ case KBUFFER_TYPE_PADDING:
+ case KBUFFER_TYPE_TIME_EXTEND:
+ case KBUFFER_TYPE_TIME_STAMP:
+ return NULL;
+ };
+
+ *size = length;
+
+ return ptr;
+}
+
+static int __next_event(struct kbuffer *kbuf)
+{
+ int type;
+
+ do {
+ kbuf->curr = kbuf->next;
+ if (kbuf->next >= kbuf->size)
+ return -1;
+ type = update_pointers(kbuf);
+ } while (type == KBUFFER_TYPE_TIME_EXTEND || type == KBUFFER_TYPE_PADDING);
+
+ return 0;
+}
+
+static int next_event(struct kbuffer *kbuf)
+{
+ return kbuf->next_event(kbuf);
+}
+
+/**
+ * kbuffer_next_event - increment the current pointer
+ * @kbuf: The kbuffer to read
+ * @ts: Address to store the next record's timestamp (may be NULL to ignore)
+ *
+ * Increments the pointers into the subbuffer of the kbuffer to point to the
+ * next event so that the next kbuffer_read_event() will return a
+ * new event.
+ *
+ * Returns the data of the next event if a new event exists on the subbuffer,
+ * NULL otherwise.
+ */
+void *kbuffer_next_event(struct kbuffer *kbuf, unsigned long long *ts)
+{
+ int ret;
+
+ if (!kbuf || !kbuf->subbuffer)
+ return NULL;
+
+ ret = next_event(kbuf);
+ if (ret < 0)
+ return NULL;
+
+ if (ts)
+ *ts = kbuf->timestamp;
+
+ return kbuf->data + kbuf->index;
+}
+
+/**
+ * kbuffer_load_subbuffer - load a new subbuffer into the kbuffer
+ * @kbuf: The kbuffer to load
+ * @subbuffer: The subbuffer to load into @kbuf.
+ *
+ * Load a new subbuffer (page) into @kbuf. This will reset all
+ * the pointers and update the @kbuf timestamp. The next read will
+ * return the first event on @subbuffer.
+ *
+ * Returns 0 on succes, -1 otherwise.
+ */
+int kbuffer_load_subbuffer(struct kbuffer *kbuf, void *subbuffer)
+{
+ unsigned long long flags;
+ void *ptr = subbuffer;
+
+ if (!kbuf || !subbuffer)
+ return -1;
+
+ kbuf->subbuffer = subbuffer;
+
+ kbuf->timestamp = read_8(kbuf, ptr);
+ ptr += 8;
+
+ kbuf->curr = 0;
+
+ if (kbuf->flags & KBUFFER_FL_LONG_8)
+ kbuf->start = 16;
+ else
+ kbuf->start = 12;
+
+ kbuf->data = subbuffer + kbuf->start;
+
+ flags = read_long(kbuf, ptr);
+ kbuf->size = (unsigned int)flags & COMMIT_MASK;
+
+ if (flags & MISSING_EVENTS) {
+ if (flags & MISSING_STORED) {
+ ptr = kbuf->data + kbuf->size;
+ kbuf->lost_events = read_long(kbuf, ptr);
+ } else
+ kbuf->lost_events = -1;
+ } else
+ kbuf->lost_events = 0;
+
+ kbuf->index = 0;
+ kbuf->next = 0;
+
+ next_event(kbuf);
+
+ return 0;
+}
+
+/**
+ * kbuffer_read_event - read the next event in the kbuffer subbuffer
+ * @kbuf: The kbuffer to read from
+ * @ts: The address to store the timestamp of the event (may be NULL to ignore)
+ *
+ * Returns a pointer to the data part of the current event.
+ * NULL if no event is left on the subbuffer.
+ */
+void *kbuffer_read_event(struct kbuffer *kbuf, unsigned long long *ts)
+{
+ if (!kbuf || !kbuf->subbuffer)
+ return NULL;
+
+ if (kbuf->curr >= kbuf->size)
+ return NULL;
+
+ if (ts)
+ *ts = kbuf->timestamp;
+ return kbuf->data + kbuf->index;
+}
+
+/**
+ * kbuffer_timestamp - Return the timestamp of the current event
+ * @kbuf: The kbuffer to read from
+ *
+ * Returns the timestamp of the current (next) event.
+ */
+unsigned long long kbuffer_timestamp(struct kbuffer *kbuf)
+{
+ return kbuf->timestamp;
+}
+
+/**
+ * kbuffer_read_at_offset - read the event that is at offset
+ * @kbuf: The kbuffer to read from
+ * @offset: The offset into the subbuffer
+ * @ts: The address to store the timestamp of the event (may be NULL to ignore)
+ *
+ * The @offset must be an index from the @kbuf subbuffer beginning.
+ * If @offset is bigger than the stored subbuffer, NULL will be returned.
+ *
+ * Returns the data of the record that is at @offset. Note, @offset does
+ * not need to be the start of the record, the offset just needs to be
+ * in the record (or beginning of it).
+ *
+ * Note, the kbuf timestamp and pointers are updated to the
+ * returned record. That is, kbuffer_read_event() will return the same
+ * data and timestamp, and kbuffer_next_event() will increment from
+ * this record.
+ */
+void *kbuffer_read_at_offset(struct kbuffer *kbuf, int offset,
+ unsigned long long *ts)
+{
+ void *data;
+
+ if (offset < kbuf->start)
+ offset = 0;
+ else
+ offset -= kbuf->start;
+
+ /* Reset the buffer */
+ kbuffer_load_subbuffer(kbuf, kbuf->subbuffer);
+
+ while (kbuf->curr < offset) {
+ data = kbuffer_next_event(kbuf, ts);
+ if (!data)
+ break;
+ }
+
+ return data;
+}
+
+/**
+ * kbuffer_subbuffer_size - the size of the loaded subbuffer
+ * @kbuf: The kbuffer to read from
+ *
+ * Returns the size of the subbuffer. Note, this size is
+ * where the last event resides. The stored subbuffer may actually be
+ * bigger due to padding and such.
+ */
+int kbuffer_subbuffer_size(struct kbuffer *kbuf)
+{
+ return kbuf->size;
+}
+
+/**
+ * kbuffer_curr_index - Return the index of the record
+ * @kbuf: The kbuffer to read from
+ *
+ * Returns the index from the start of the data part of
+ * the subbuffer to the current location. Note this is not
+ * from the start of the subbuffer. An index of zero will
+ * point to the first record. Use kbuffer_curr_offset() for
+ * the actually offset (that can be used by kbuffer_read_at_offset())
+ */
+int kbuffer_curr_index(struct kbuffer *kbuf)
+{
+ return kbuf->curr;
+}
+
+/**
+ * kbuffer_curr_offset - Return the offset of the record
+ * @kbuf: The kbuffer to read from
+ *
+ * Returns the offset from the start of the subbuffer to the
+ * current location.
+ */
+int kbuffer_curr_offset(struct kbuffer *kbuf)
+{
+ return kbuf->curr + kbuf->start;
+}
+
+/**
+ * kbuffer_event_size - return the size of the event data
+ * @kbuf: The kbuffer to read
+ *
+ * Returns the size of the event data (the payload not counting
+ * the meta data of the record) of the current event.
+ */
+int kbuffer_event_size(struct kbuffer *kbuf)
+{
+ return kbuf->next - kbuf->index;
+}
+
+/**
+ * kbuffer_curr_size - return the size of the entire record
+ * @kbuf: The kbuffer to read
+ *
+ * Returns the size of the entire record (meta data and payload)
+ * of the current event.
+ */
+int kbuffer_curr_size(struct kbuffer *kbuf)
+{
+ return kbuf->next - kbuf->curr;
+}
+
+/**
+ * kbuffer_missed_events - return the # of missed events from last event.
+ * @kbuf: The kbuffer to read from
+ *
+ * Returns the # of missed events (if recorded) before the current
+ * event. Note, only events on the beginning of a subbuffer can
+ * have missed events, all other events within the buffer will be
+ * zero.
+ */
+int kbuffer_missed_events(struct kbuffer *kbuf)
+{
+ /* Only the first event can have missed events */
+ if (kbuf->curr)
+ return 0;
+
+ return kbuf->lost_events;
+}
+
+/**
+ * kbuffer_set_old_forma - set the kbuffer to use the old format parsing
+ * @kbuf: The kbuffer to set
+ *
+ * This is obsolete (or should be). The first kernels to use the
+ * new ring buffer had a slightly different ring buffer format
+ * (2.6.30 and earlier). It is still somewhat supported by kbuffer,
+ * but should not be counted on in the future.
+ */
+void kbuffer_set_old_format(struct kbuffer *kbuf)
+{
+ kbuf->flags |= KBUFFER_FL_OLD_FORMAT;
+
+ kbuf->next_event = __old_next_event;
+}
projects / karo-tx-linux.git / commitdiff