| 1 | /* |
| 2 | * include/linux/ltt-relay.h |
| 3 | * |
| 4 | * Copyright (C) 2008,2009 - Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> |
| 5 | * |
| 6 | * Dual LGPL v2.1/GPL v2 license. |
| 7 | * |
| 8 | * Credits to Steven Rostedt for proposing to use an extra-subbuffer owned by |
| 9 | * the reader in flight recorder mode. |
| 10 | */ |
| 11 | |
| 12 | #ifndef _LINUX_LTT_RELAY_H |
| 13 | #define _LINUX_LTT_RELAY_H |
| 14 | |
| 15 | #include <linux/types.h> |
| 16 | #include <linux/sched.h> |
| 17 | #include <linux/timer.h> |
| 18 | #include <linux/wait.h> |
| 19 | #include <linux/fs.h> |
| 20 | #include <linux/poll.h> |
| 21 | #include <linux/kref.h> |
| 22 | #include <linux/mm.h> |
| 23 | #include <linux/ltt-channels.h> |
| 24 | |
| 25 | #include "ltt-tracer-core.h" |
| 26 | |
| 27 | /* Use lowest pointer bit to show the sub-buffer has no reference. */ |
| 28 | #define RCHAN_NOREF_FLAG 0x1UL |
| 29 | |
| 30 | #define RCHAN_SB_IS_NOREF(x) ((unsigned long)(x) & RCHAN_NOREF_FLAG) |
| 31 | #define RCHAN_SB_SET_NOREF(x) \ |
| 32 | (x = (struct chanbuf_page *)((unsigned long)(x) | RCHAN_NOREF_FLAG)) |
| 33 | #define RCHAN_SB_CLEAR_NOREF(x) \ |
| 34 | (x = (struct chanbuf_page *)((unsigned long)(x) & ~RCHAN_NOREF_FLAG)) |
| 35 | |
| 36 | struct ltt_trace; |
| 37 | |
| 38 | struct chanbuf_page { |
| 39 | void *virt; /* page virtual address (cached) */ |
| 40 | struct page *page; /* pointer to page structure */ |
| 41 | }; |
| 42 | |
| 43 | struct chanbuf_sb { |
| 44 | struct chanbuf_page *pages; /* Pointer to rchan pages for subbuf */ |
| 45 | }; |
| 46 | |
| 47 | struct ltt_chanbuf_alloc { |
| 48 | struct chanbuf_sb *buf_wsb; /* Array of rchan_sb for writer */ |
| 49 | struct chanbuf_sb buf_rsb; /* chanbuf_sb for reader */ |
| 50 | void **_virt; /* Array of pointers to page addr */ |
| 51 | struct page **_pages; /* Array of pointers to pages */ |
| 52 | struct dentry *dentry; /* Associated file dentry */ |
| 53 | unsigned int nr_pages; /* Number pages in buffer */ |
| 54 | |
| 55 | struct ltt_chan_alloc *chan; /* Associated channel */ |
| 56 | unsigned int cpu; /* This buffer's cpu */ |
| 57 | unsigned int allocated:1; /* Bool: is buffer allocated ? */ |
| 58 | }; |
| 59 | |
| 60 | int ltt_chanbuf_alloc_create(struct ltt_chanbuf_alloc *buf, |
| 61 | struct ltt_chan_alloc *chan, int cpu); |
| 62 | void ltt_chanbuf_alloc_free(struct ltt_chanbuf_alloc *buf); |
| 63 | int ltt_chan_alloc_init(struct ltt_chan_alloc *chan, struct ltt_trace *trace, |
| 64 | const char *base_filename, |
| 65 | struct dentry *parent, size_t sb_size, |
| 66 | size_t n_sb, int extra_reader_sb, int overwrite); |
| 67 | void ltt_chan_alloc_free(struct ltt_chan_alloc *chan); |
| 68 | void ltt_chan_alloc_remove_files(struct ltt_chan_alloc *chan); |
| 69 | int ltt_chanbuf_create_file(const char *filename, struct dentry *parent, |
| 70 | int mode, struct ltt_chanbuf *buf); |
| 71 | int ltt_chanbuf_remove_file(struct ltt_chanbuf *buf); |
| 72 | |
| 73 | void ltt_chan_for_each_channel(void (*cb) (struct ltt_chanbuf *buf), int cpu); |
| 74 | |
| 75 | extern void _ltt_relay_write(struct ltt_chanbuf_alloc *bufa, |
| 76 | size_t offset, const void *src, size_t len, |
| 77 | ssize_t pagecpy); |
| 78 | |
| 79 | extern void _ltt_relay_strncpy(struct ltt_chanbuf_alloc *bufa, |
| 80 | size_t offset, const void *src, size_t len, |
| 81 | ssize_t pagecpy); |
| 82 | |
| 83 | extern void _ltt_relay_strncpy_fixup(struct ltt_chanbuf_alloc *bufa, |
| 84 | size_t offset, size_t len, size_t copied, |
| 85 | int terminated); |
| 86 | |
| 87 | extern int ltt_relay_read(struct ltt_chanbuf_alloc *bufa, |
| 88 | size_t offset, void *dest, size_t len); |
| 89 | |
| 90 | extern int ltt_relay_read_cstr(struct ltt_chanbuf_alloc *bufa, |
| 91 | size_t offset, void *dest, size_t len); |
| 92 | |
| 93 | extern struct page *ltt_relay_read_get_page(struct ltt_chanbuf_alloc *bufa, |
| 94 | size_t offset); |
| 95 | |
| 96 | /* |
| 97 | * Return the address where a given offset is located. |
| 98 | * Should be used to get the current subbuffer header pointer. Given we know |
| 99 | * it's never on a page boundary, it's safe to write directly to this address, |
| 100 | * as long as the write is never bigger than a page size. |
| 101 | */ |
| 102 | extern void *ltt_relay_offset_address(struct ltt_chanbuf_alloc *bufa, |
| 103 | size_t offset); |
| 104 | extern void *ltt_relay_read_offset_address(struct ltt_chanbuf_alloc *bufa, |
| 105 | size_t offset); |
| 106 | |
| 107 | #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS |
| 108 | static __inline__ |
| 109 | void ltt_relay_do_copy(void *dest, const void *src, size_t len) |
| 110 | { |
| 111 | switch (len) { |
| 112 | case 0: |
| 113 | break; |
| 114 | case 1: |
| 115 | *(u8 *)dest = *(const u8 *)src; |
| 116 | break; |
| 117 | case 2: |
| 118 | *(u16 *)dest = *(const u16 *)src; |
| 119 | break; |
| 120 | case 4: |
| 121 | *(u32 *)dest = *(const u32 *)src; |
| 122 | break; |
| 123 | case 8: |
| 124 | *(u64 *)dest = *(const u64 *)src; |
| 125 | break; |
| 126 | default: |
| 127 | /* |
| 128 | * What we really want here is an __inline__ memcpy, but we don't |
| 129 | * have constants, so gcc generally uses a function call. |
| 130 | */ |
| 131 | for (; len > 0; len--) |
| 132 | *(u8 *)dest++ = *(const u8 *)src++; |
| 133 | } |
| 134 | } |
| 135 | #else |
| 136 | /* |
| 137 | * Returns whether the dest and src addresses are aligned on |
| 138 | * min(sizeof(void *), len). Call this with statically known len for efficiency. |
| 139 | */ |
| 140 | static __inline__ |
| 141 | int addr_aligned(const void *dest, const void *src, size_t len) |
| 142 | { |
| 143 | if (ltt_align((size_t)dest, len)) |
| 144 | return 0; |
| 145 | if (ltt_align((size_t)src, len)) |
| 146 | return 0; |
| 147 | return 1; |
| 148 | } |
| 149 | |
| 150 | static __inline__ |
| 151 | void ltt_relay_do_copy(void *dest, const void *src, size_t len) |
| 152 | { |
| 153 | switch (len) { |
| 154 | case 0: |
| 155 | break; |
| 156 | case 1: |
| 157 | *(u8 *)dest = *(const u8 *)src; |
| 158 | break; |
| 159 | case 2: |
| 160 | if (unlikely(!addr_aligned(dest, src, 2))) |
| 161 | goto memcpy_fallback; |
| 162 | *(u16 *)dest = *(const u16 *)src; |
| 163 | break; |
| 164 | case 4: |
| 165 | if (unlikely(!addr_aligned(dest, src, 4))) |
| 166 | goto memcpy_fallback; |
| 167 | *(u32 *)dest = *(const u32 *)src; |
| 168 | break; |
| 169 | case 8: |
| 170 | if (unlikely(!addr_aligned(dest, src, 8))) |
| 171 | goto memcpy_fallback; |
| 172 | *(u64 *)dest = *(const u64 *)src; |
| 173 | break; |
| 174 | default: |
| 175 | goto memcpy_fallback; |
| 176 | } |
| 177 | return; |
| 178 | |
| 179 | memcpy_fallback: |
| 180 | /* |
| 181 | * What we really want here is an inline memcpy, but we don't |
| 182 | * have constants, so gcc generally uses a function call. |
| 183 | */ |
| 184 | for (; len > 0; len--) |
| 185 | *(u8 *)dest++ = *(const u8 *)src++; |
| 186 | } |
| 187 | #endif |
| 188 | |
| 189 | /* |
| 190 | * ltt_relay_do_memset - write character into dest. |
| 191 | * @dest: destination |
| 192 | * @src: source character |
| 193 | * @len: length to write |
| 194 | */ |
| 195 | static __inline__ |
| 196 | void ltt_relay_do_memset(void *dest, char src, size_t len) |
| 197 | { |
| 198 | /* |
| 199 | * What we really want here is an __inline__ memset, but we |
| 200 | * don't have constants, so gcc generally uses a function call. |
| 201 | */ |
| 202 | for (; len > 0; len--) |
| 203 | *(u8 *)dest++ = src; |
| 204 | } |
| 205 | |
| 206 | |
| 207 | /* |
| 208 | * ltt_relay_do_strncpy - copy a string up to a certain number of bytes |
| 209 | * @dest: destination |
| 210 | * @src: source |
| 211 | * @len: max. length to copy |
| 212 | * @terminated: output string ends with \0 (output) |
| 213 | * |
| 214 | * returns the number of bytes copied. Does not finalize with \0 if len is |
| 215 | * reached. |
| 216 | */ |
| 217 | static __inline__ |
| 218 | size_t ltt_relay_do_strncpy(void *dest, const void *src, size_t len, |
| 219 | int *terminated) |
| 220 | { |
| 221 | size_t orig_len = len; |
| 222 | |
| 223 | *terminated = 0; |
| 224 | /* |
| 225 | * What we really want here is an __inline__ strncpy, but we |
| 226 | * don't have constants, so gcc generally uses a function call. |
| 227 | */ |
| 228 | for (; len > 0; len--) { |
| 229 | *(u8 *)dest = ACCESS_ONCE(*(const u8 *)src); |
| 230 | /* Check with dest, because src may be modified concurrently */ |
| 231 | if (*(const u8 *)dest == '\0') { |
| 232 | len--; |
| 233 | *terminated = 1; |
| 234 | break; |
| 235 | } |
| 236 | dest++; |
| 237 | src++; |
| 238 | } |
| 239 | return orig_len - len; |
| 240 | } |
| 241 | |
| 242 | static __inline__ |
| 243 | int ltt_relay_write(struct ltt_chanbuf_alloc *bufa, |
| 244 | struct ltt_chan_alloc *chana, size_t offset, |
| 245 | const void *src, size_t len) |
| 246 | { |
| 247 | size_t sbidx, index; |
| 248 | ssize_t pagecpy; |
| 249 | struct chanbuf_page *rpages; |
| 250 | |
| 251 | offset &= chana->buf_size - 1; |
| 252 | sbidx = offset >> chana->sb_size_order; |
| 253 | index = (offset & (chana->sb_size - 1)) >> PAGE_SHIFT; |
| 254 | pagecpy = min_t(size_t, len, (- offset) & ~PAGE_MASK); |
| 255 | rpages = bufa->buf_wsb[sbidx].pages; |
| 256 | WARN_ON_ONCE(RCHAN_SB_IS_NOREF(rpages)); |
| 257 | ltt_relay_do_copy(rpages[index].virt + (offset & ~PAGE_MASK), |
| 258 | src, pagecpy); |
| 259 | |
| 260 | if (unlikely(len != pagecpy)) |
| 261 | _ltt_relay_write(bufa, offset, src, len, pagecpy); |
| 262 | return len; |
| 263 | } |
| 264 | |
| 265 | static __inline__ |
| 266 | int ltt_relay_strncpy(struct ltt_chanbuf_alloc *bufa, |
| 267 | struct ltt_chan_alloc *chana, size_t offset, |
| 268 | const void *src, size_t len) |
| 269 | { |
| 270 | size_t sbidx, index; |
| 271 | ssize_t pagecpy, copied; |
| 272 | struct chanbuf_page *rpages; |
| 273 | int terminated; |
| 274 | |
| 275 | offset &= chana->buf_size - 1; |
| 276 | sbidx = offset >> chana->sb_size_order; |
| 277 | index = (offset & (chana->sb_size - 1)) >> PAGE_SHIFT; |
| 278 | pagecpy = min_t(size_t, len, (- offset) & ~PAGE_MASK); |
| 279 | rpages = bufa->buf_wsb[sbidx].pages; |
| 280 | WARN_ON_ONCE(RCHAN_SB_IS_NOREF(rpages)); |
| 281 | copied = ltt_relay_do_strncpy(rpages[index].virt |
| 282 | + (offset & ~PAGE_MASK), |
| 283 | src, pagecpy, &terminated); |
| 284 | if (unlikely(copied < pagecpy || ((len == pagecpy) && !terminated))) |
| 285 | _ltt_relay_strncpy_fixup(bufa, offset, len, copied, |
| 286 | terminated); |
| 287 | else { |
| 288 | if (unlikely(len != pagecpy)) |
| 289 | _ltt_relay_strncpy(bufa, offset, src, len, pagecpy); |
| 290 | } |
| 291 | return len; |
| 292 | } |
| 293 | |
| 294 | /** |
| 295 | * ltt_clear_noref_flag - Clear the noref subbuffer flag, for writer. |
| 296 | */ |
| 297 | static __inline__ |
| 298 | void ltt_clear_noref_flag(struct ltt_chanbuf_alloc *bufa, long idx) |
| 299 | { |
| 300 | struct chanbuf_page *sb_pages, *new_sb_pages; |
| 301 | |
| 302 | sb_pages = bufa->buf_wsb[idx].pages; |
| 303 | for (;;) { |
| 304 | if (!RCHAN_SB_IS_NOREF(sb_pages)) |
| 305 | return; /* Already writing to this buffer */ |
| 306 | new_sb_pages = sb_pages; |
| 307 | RCHAN_SB_CLEAR_NOREF(new_sb_pages); |
| 308 | new_sb_pages = cmpxchg(&bufa->buf_wsb[idx].pages, |
| 309 | sb_pages, new_sb_pages); |
| 310 | if (likely(new_sb_pages == sb_pages)) |
| 311 | break; |
| 312 | sb_pages = new_sb_pages; |
| 313 | } |
| 314 | } |
| 315 | |
| 316 | /** |
| 317 | * ltt_set_noref_flag - Set the noref subbuffer flag, for writer. |
| 318 | */ |
| 319 | static __inline__ |
| 320 | void ltt_set_noref_flag(struct ltt_chanbuf_alloc *bufa, long idx) |
| 321 | { |
| 322 | struct chanbuf_page *sb_pages, *new_sb_pages; |
| 323 | |
| 324 | sb_pages = bufa->buf_wsb[idx].pages; |
| 325 | for (;;) { |
| 326 | if (RCHAN_SB_IS_NOREF(sb_pages)) |
| 327 | return; /* Already set */ |
| 328 | new_sb_pages = sb_pages; |
| 329 | RCHAN_SB_SET_NOREF(new_sb_pages); |
| 330 | new_sb_pages = cmpxchg(&bufa->buf_wsb[idx].pages, |
| 331 | sb_pages, new_sb_pages); |
| 332 | if (likely(new_sb_pages == sb_pages)) |
| 333 | break; |
| 334 | sb_pages = new_sb_pages; |
| 335 | } |
| 336 | } |
| 337 | |
| 338 | /** |
| 339 | * update_read_sb_index - Read-side subbuffer index update. |
| 340 | */ |
| 341 | static __inline__ |
| 342 | int update_read_sb_index(struct ltt_chanbuf_alloc *bufa, |
| 343 | struct ltt_chan_alloc *chana, |
| 344 | long consumed_idx) |
| 345 | { |
| 346 | struct chanbuf_page *old_wpage, *new_wpage; |
| 347 | |
| 348 | if (unlikely(chana->extra_reader_sb)) { |
| 349 | /* |
| 350 | * Exchange the target writer subbuffer with our own unused |
| 351 | * subbuffer. |
| 352 | */ |
| 353 | old_wpage = bufa->buf_wsb[consumed_idx].pages; |
| 354 | if (unlikely(!RCHAN_SB_IS_NOREF(old_wpage))) |
| 355 | return -EAGAIN; |
| 356 | WARN_ON_ONCE(!RCHAN_SB_IS_NOREF(bufa->buf_rsb.pages)); |
| 357 | new_wpage = cmpxchg(&bufa->buf_wsb[consumed_idx].pages, |
| 358 | old_wpage, |
| 359 | bufa->buf_rsb.pages); |
| 360 | if (unlikely(old_wpage != new_wpage)) |
| 361 | return -EAGAIN; |
| 362 | bufa->buf_rsb.pages = new_wpage; |
| 363 | RCHAN_SB_CLEAR_NOREF(bufa->buf_rsb.pages); |
| 364 | } else { |
| 365 | /* No page exchange, use the writer page directly */ |
| 366 | bufa->buf_rsb.pages = bufa->buf_wsb[consumed_idx].pages; |
| 367 | RCHAN_SB_CLEAR_NOREF(bufa->buf_rsb.pages); |
| 368 | } |
| 369 | return 0; |
| 370 | } |
| 371 | |
| 372 | ssize_t ltt_relay_file_splice_read(struct file *in, loff_t *ppos, |
| 373 | struct pipe_inode_info *pipe, size_t len, |
| 374 | unsigned int flags); |
| 375 | loff_t ltt_relay_no_llseek(struct file *file, loff_t offset, int origin); |
| 376 | |
| 377 | #endif /* _LINUX_LTT_RELAY_H */ |