| 1 | /* Copyright (C) 2009 Pierre-Marc Fournier |
| 2 | * |
| 3 | * This library is free software; you can redistribute it and/or |
| 4 | * modify it under the terms of the GNU Lesser General Public |
| 5 | * License as published by the Free Software Foundation; either |
| 6 | * version 2.1 of the License, or (at your option) any later version. |
| 7 | * |
| 8 | * This library is distributed in the hope that it will be useful, |
| 9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 11 | * Lesser General Public License for more details. |
| 12 | * |
| 13 | * You should have received a copy of the GNU Lesser General Public |
| 14 | * License along with this library; if not, write to the Free Software |
| 15 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 16 | */ |
| 17 | |
| 18 | #include <stdlib.h> |
| 19 | #include <assert.h> |
| 20 | #include <byteswap.h> |
| 21 | |
| 22 | #include "ust/ustconsumer.h" |
| 23 | #include "buffers.h" |
| 24 | #include "tracer.h" |
| 25 | #include "usterr_signal_safe.h" |
| 26 | |
| 27 | /* This truncates to an offset in the buffer. */ |
| 28 | #define USTD_BUFFER_TRUNC(offset, bufinfo) \ |
| 29 | ((offset) & (~(((bufinfo)->subbuf_size*(bufinfo)->n_subbufs)-1))) |
| 30 | |
| 31 | #define LTT_MAGIC_NUMBER 0x00D6B7ED |
| 32 | #define LTT_REV_MAGIC_NUMBER 0xEDB7D600 |
| 33 | |
| 34 | |
| 35 | static void ltt_relay_print_subbuffer_errors( |
| 36 | struct buffer_info *buf, |
| 37 | long cons_off, int cpu) |
| 38 | { |
| 39 | struct ust_buffer *ust_buf = buf->bufstruct_mem; |
| 40 | long cons_idx, commit_count, commit_count_mask, write_offset; |
| 41 | |
| 42 | cons_idx = SUBBUF_INDEX(cons_off, buf); |
| 43 | commit_count = uatomic_read(&ust_buf->commit_seq[cons_idx]); |
| 44 | commit_count_mask = (~0UL >> get_count_order(buf->n_subbufs)); |
| 45 | |
| 46 | /* |
| 47 | * No need to order commit_count and write_offset reads because we |
| 48 | * execute after trace is stopped when there are no readers left. |
| 49 | */ |
| 50 | write_offset = uatomic_read(&ust_buf->offset); |
| 51 | WARN( "LTT : unread channel %s offset is %ld " |
| 52 | "and cons_off : %ld (cpu %d)\n", |
| 53 | buf->channel, write_offset, cons_off, cpu); |
| 54 | /* Check each sub-buffer for non filled commit count */ |
| 55 | if (((commit_count - buf->subbuf_size) & commit_count_mask) |
| 56 | - (BUFFER_TRUNC(cons_off, buf) >> get_count_order(buf->n_subbufs)) != 0) { |
| 57 | ERR("LTT : %s : subbuffer %lu has non filled " |
| 58 | "commit count [seq] [%lu].\n", |
| 59 | buf->channel, cons_idx, commit_count); |
| 60 | } |
| 61 | ERR("LTT : %s : commit count : %lu, subbuf size %d\n", |
| 62 | buf->channel, commit_count, |
| 63 | buf->subbuf_size); |
| 64 | } |
| 65 | |
| 66 | static void ltt_relay_print_errors(struct buffer_info *buf, int cpu) |
| 67 | { |
| 68 | struct ust_buffer *ust_buf = buf->bufstruct_mem; |
| 69 | long cons_off; |
| 70 | |
| 71 | for (cons_off = uatomic_read(&ust_buf->consumed); |
| 72 | (SUBBUF_TRUNC(uatomic_read(&ust_buf->offset), buf) |
| 73 | - cons_off) > 0; |
| 74 | cons_off = SUBBUF_ALIGN(cons_off, buf)) |
| 75 | ltt_relay_print_subbuffer_errors(buf, cons_off, cpu); |
| 76 | } |
| 77 | |
| 78 | static void ltt_relay_print_buffer_errors(struct buffer_info *buf, int cpu) |
| 79 | { |
| 80 | struct ust_buffer *ust_buf = buf->bufstruct_mem; |
| 81 | |
| 82 | if (uatomic_read(&ust_buf->events_lost)) |
| 83 | ERR("channel %s: %ld events lost (cpu %d)", |
| 84 | buf->channel, |
| 85 | uatomic_read(&ust_buf->events_lost), cpu); |
| 86 | if (uatomic_read(&ust_buf->corrupted_subbuffers)) |
| 87 | ERR("channel %s : %ld corrupted subbuffers (cpu %d)", |
| 88 | buf->channel, |
| 89 | uatomic_read(&ust_buf->corrupted_subbuffers), cpu); |
| 90 | |
| 91 | ltt_relay_print_errors(buf, cpu); |
| 92 | } |
| 93 | |
| 94 | /* Returns the size of a subbuffer size. This is the size that |
| 95 | * will need to be written to disk. |
| 96 | * |
| 97 | * @subbuffer: pointer to the beginning of the subbuffer (the |
| 98 | * beginning of its header) |
| 99 | */ |
| 100 | |
| 101 | size_t subbuffer_data_size(void *subbuf) |
| 102 | { |
| 103 | struct ltt_subbuffer_header *header = subbuf; |
| 104 | int reverse; |
| 105 | u32 data_size; |
| 106 | |
| 107 | if(header->magic_number == LTT_MAGIC_NUMBER) { |
| 108 | reverse = 0; |
| 109 | } |
| 110 | else if(header->magic_number == LTT_REV_MAGIC_NUMBER) { |
| 111 | reverse = 1; |
| 112 | } |
| 113 | else { |
| 114 | return -1; |
| 115 | } |
| 116 | |
| 117 | data_size = header->sb_size; |
| 118 | if(reverse) |
| 119 | data_size = bswap_32(data_size); |
| 120 | |
| 121 | return data_size; |
| 122 | } |
| 123 | |
| 124 | |
| 125 | void finish_consuming_dead_subbuffer(struct ustconsumer_callbacks *callbacks, struct buffer_info *buf) |
| 126 | { |
| 127 | struct ust_buffer *ust_buf = buf->bufstruct_mem; |
| 128 | unsigned long n_subbufs_order = get_count_order(buf->n_subbufs); |
| 129 | unsigned long commit_seq_mask = (~0UL >> n_subbufs_order); |
| 130 | unsigned long cons_off; |
| 131 | int ret; |
| 132 | |
| 133 | DBG("processing dead buffer (%s)", buf->name); |
| 134 | DBG("consumed offset is %ld (%s)", uatomic_read(&ust_buf->consumed), |
| 135 | buf->name); |
| 136 | DBG("write offset is %ld (%s)", uatomic_read(&ust_buf->offset), |
| 137 | buf->name); |
| 138 | |
| 139 | /* |
| 140 | * Iterate on subbuffers to recover, including the one the writer |
| 141 | * just wrote data into. Using write position - 1 since the writer |
| 142 | * position points into the position that is going to be written. |
| 143 | */ |
| 144 | for (cons_off = uatomic_read(&ust_buf->consumed); |
| 145 | (long) (SUBBUF_TRUNC(uatomic_read(&ust_buf->offset) - 1, buf) |
| 146 | - cons_off) >= 0; |
| 147 | cons_off = SUBBUF_ALIGN(cons_off, buf)) { |
| 148 | /* |
| 149 | * commit_seq is the offset in the buffer of the end of the last sequential commit. |
| 150 | * Bytes beyond this limit cannot be recovered. This is a free-running counter. |
| 151 | */ |
| 152 | unsigned long commit_seq = |
| 153 | uatomic_read(&ust_buf->commit_seq[SUBBUF_INDEX(cons_off, buf)]); |
| 154 | struct ltt_subbuffer_header *header = |
| 155 | (struct ltt_subbuffer_header *)((char *) buf->mem |
| 156 | + SUBBUF_INDEX(cons_off, buf) * buf->subbuf_size); |
| 157 | unsigned long valid_length; |
| 158 | |
| 159 | /* Check if subbuf was fully written. This is from Mathieu's algorithm/paper. */ |
| 160 | if (((commit_seq - buf->subbuf_size) & commit_seq_mask) |
| 161 | - (USTD_BUFFER_TRUNC(uatomic_read(&ust_buf->consumed), buf) >> n_subbufs_order) == 0 |
| 162 | && header->data_size != 0xffffffff) { |
| 163 | assert(header->sb_size != 0xffffffff); |
| 164 | /* |
| 165 | * If it was fully written, we only check the data_size. |
| 166 | * This is the amount of valid data at the beginning of |
| 167 | * the subbuffer. |
| 168 | */ |
| 169 | valid_length = header->data_size; |
| 170 | DBG("writing full subbuffer (%ld) with valid_length = %ld", |
| 171 | SUBBUF_INDEX(cons_off, buf), valid_length); |
| 172 | } else { |
| 173 | /* |
| 174 | * If the subbuffer was not fully written, then we don't |
| 175 | * check data_size because it hasn't been written yet. |
| 176 | * Instead we check commit_seq and use it to choose a |
| 177 | * value for data_size. The viewer will need this value |
| 178 | * when parsing. Generally, this will happen only for |
| 179 | * the last subbuffer. However, if we have threads still |
| 180 | * holding reserved slots in the previous subbuffers, |
| 181 | * which could happen for other subbuffers prior to the |
| 182 | * last one. Note that when data_size is set, the |
| 183 | * commit_seq count is still at a value that shows the |
| 184 | * amount of valid data to read. It's only _after_ |
| 185 | * writing data_size that commit_seq is updated to |
| 186 | * include the end-of-buffer padding. |
| 187 | */ |
| 188 | valid_length = commit_seq & (buf->subbuf_size - 1); |
| 189 | DBG("writing unfull subbuffer (%ld) with valid_length = %ld", |
| 190 | SUBBUF_INDEX(cons_off, buf), valid_length); |
| 191 | header->data_size = valid_length; |
| 192 | header->sb_size = PAGE_ALIGN(valid_length); |
| 193 | } |
| 194 | |
| 195 | if (callbacks->on_read_partial_subbuffer) { |
| 196 | ret = callbacks->on_read_partial_subbuffer(callbacks, buf, |
| 197 | SUBBUF_INDEX(cons_off, buf), |
| 198 | valid_length); |
| 199 | if (ret < 0) |
| 200 | break; /* Error happened */ |
| 201 | } |
| 202 | } |
| 203 | /* Increment the consumed offset */ |
| 204 | uatomic_set(&ust_buf->consumed, cons_off); |
| 205 | ltt_relay_print_buffer_errors(buf, buf->channel_cpu); |
| 206 | } |
| 207 | |