1 /* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
3 * ring_buffer_backend.c
5 * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 #include <linux/stddef.h>
9 #include <linux/module.h>
10 #include <linux/string.h>
11 #include <linux/bitops.h>
12 #include <linux/delay.h>
13 #include <linux/errno.h>
14 #include <linux/slab.h>
15 #include <linux/cpu.h>
17 #include <linux/vmalloc.h>
19 #include <wrapper/mm.h>
20 #include <wrapper/vmalloc.h> /* for wrapper_vmalloc_sync_mappings() */
21 #include <ringbuffer/config.h>
22 #include <ringbuffer/backend.h>
23 #include <ringbuffer/frontend.h>
26 * lib_ring_buffer_backend_allocate - allocate a channel buffer
27 * @config: ring buffer instance configuration
28 * @buf: the buffer struct
29 * @size: total size of the buffer
30 * @num_subbuf: number of subbuffers
31 * @extra_reader_sb: need extra subbuffer for reader
34 int lib_ring_buffer_backend_allocate(const struct lttng_kernel_ring_buffer_config
*config
,
35 struct lttng_kernel_ring_buffer_backend
*bufb
,
36 size_t size
, size_t num_subbuf
,
39 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
40 unsigned long j
, num_pages
, num_pages_per_subbuf
, page_idx
= 0;
41 unsigned long subbuf_size
, mmap_offset
= 0;
42 unsigned long num_subbuf_alloc
;
46 num_pages
= size
>> PAGE_SHIFT
;
49 * Verify that there is enough free pages available on the system for
50 * the current allocation request.
51 * wrapper_check_enough_free_pages uses si_mem_available() if available
52 * and returns if there should be enough free pages based on the
55 if (!wrapper_check_enough_free_pages(num_pages
))
56 goto not_enough_pages
;
59 * Set the current user thread as the first target of the OOM killer.
60 * If the estimate received by si_mem_available() was off, and we do
61 * end up running out of memory because of this buffer allocation, we
62 * want to kill the offending app first.
64 wrapper_set_current_oom_origin();
66 num_pages_per_subbuf
= num_pages
>> get_count_order(num_subbuf
);
67 subbuf_size
= chanb
->subbuf_size
;
68 num_subbuf_alloc
= num_subbuf
;
70 if (extra_reader_sb
) {
71 num_pages
+= num_pages_per_subbuf
; /* Add pages for reader */
75 pages
= vmalloc_node(ALIGN(sizeof(*pages
) * num_pages
,
76 1 << INTERNODE_CACHE_SHIFT
),
77 cpu_to_node(max(bufb
->cpu
, 0)));
81 bufb
->array
= lttng_kvmalloc_node(ALIGN(sizeof(*bufb
->array
)
83 1 << INTERNODE_CACHE_SHIFT
),
84 GFP_KERNEL
| __GFP_NOWARN
,
85 cpu_to_node(max(bufb
->cpu
, 0)));
86 if (unlikely(!bufb
->array
))
89 for (i
= 0; i
< num_pages
; i
++) {
90 pages
[i
] = alloc_pages_node(cpu_to_node(max(bufb
->cpu
, 0)),
91 GFP_KERNEL
| __GFP_NOWARN
| __GFP_ZERO
, 0);
92 if (unlikely(!pages
[i
]))
95 bufb
->num_pages_per_subbuf
= num_pages_per_subbuf
;
97 /* Allocate backend pages array elements */
98 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
100 lttng_kvzalloc_node(ALIGN(
101 sizeof(struct lttng_kernel_ring_buffer_backend_pages
) +
102 sizeof(struct lttng_kernel_ring_buffer_backend_page
)
103 * num_pages_per_subbuf
,
104 1 << INTERNODE_CACHE_SHIFT
),
105 GFP_KERNEL
| __GFP_NOWARN
,
106 cpu_to_node(max(bufb
->cpu
, 0)));
111 /* Allocate write-side subbuffer table */
112 bufb
->buf_wsb
= lttng_kvzalloc_node(ALIGN(
113 sizeof(struct lttng_kernel_ring_buffer_backend_subbuffer
)
115 1 << INTERNODE_CACHE_SHIFT
),
116 GFP_KERNEL
| __GFP_NOWARN
,
117 cpu_to_node(max(bufb
->cpu
, 0)));
118 if (unlikely(!bufb
->buf_wsb
))
121 for (i
= 0; i
< num_subbuf
; i
++)
122 bufb
->buf_wsb
[i
].id
= subbuffer_id(config
, 0, 1, i
);
124 /* Assign read-side subbuffer table */
126 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1,
127 num_subbuf_alloc
- 1);
129 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1, 0);
131 /* Allocate subbuffer packet counter table */
132 bufb
->buf_cnt
= lttng_kvzalloc_node(ALIGN(
133 sizeof(struct lttng_kernel_ring_buffer_backend_counts
)
135 1 << INTERNODE_CACHE_SHIFT
),
136 GFP_KERNEL
| __GFP_NOWARN
,
137 cpu_to_node(max(bufb
->cpu
, 0)));
138 if (unlikely(!bufb
->buf_cnt
))
141 /* Assign pages to page index */
142 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
143 for (j
= 0; j
< num_pages_per_subbuf
; j
++) {
144 CHAN_WARN_ON(chanb
, page_idx
> num_pages
);
145 bufb
->array
[i
]->p
[j
].virt
= page_address(pages
[page_idx
]);
146 bufb
->array
[i
]->p
[j
].pfn
= page_to_pfn(pages
[page_idx
]);
149 if (config
->output
== RING_BUFFER_MMAP
) {
150 bufb
->array
[i
]->mmap_offset
= mmap_offset
;
151 mmap_offset
+= subbuf_size
;
156 * If kmalloc ever uses vmalloc underneath, make sure the buffer pages
159 wrapper_vmalloc_sync_mappings();
160 wrapper_clear_current_oom_origin();
165 lttng_kvfree(bufb
->buf_wsb
);
167 for (i
= 0; (i
< num_subbuf_alloc
&& bufb
->array
[i
]); i
++)
168 lttng_kvfree(bufb
->array
[i
]);
170 /* Free all allocated pages */
171 for (i
= 0; (i
< num_pages
&& pages
[i
]); i
++)
172 __free_page(pages
[i
]);
173 lttng_kvfree(bufb
->array
);
177 wrapper_clear_current_oom_origin();
182 int lib_ring_buffer_backend_create(struct lttng_kernel_ring_buffer_backend
*bufb
,
183 struct channel_backend
*chanb
, int cpu
)
185 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
187 bufb
->chan
= container_of(chanb
, struct lttng_kernel_ring_buffer_channel
, backend
);
190 return lib_ring_buffer_backend_allocate(config
, bufb
, chanb
->buf_size
,
192 chanb
->extra_reader_sb
);
195 void lib_ring_buffer_backend_free(struct lttng_kernel_ring_buffer_backend
*bufb
)
197 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
198 unsigned long i
, j
, num_subbuf_alloc
;
200 num_subbuf_alloc
= chanb
->num_subbuf
;
201 if (chanb
->extra_reader_sb
)
204 lttng_kvfree(bufb
->buf_wsb
);
205 lttng_kvfree(bufb
->buf_cnt
);
206 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
207 for (j
= 0; j
< bufb
->num_pages_per_subbuf
; j
++)
208 __free_page(pfn_to_page(bufb
->array
[i
]->p
[j
].pfn
));
209 lttng_kvfree(bufb
->array
[i
]);
211 lttng_kvfree(bufb
->array
);
215 void lib_ring_buffer_backend_reset(struct lttng_kernel_ring_buffer_backend
*bufb
)
217 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
218 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
219 unsigned long num_subbuf_alloc
;
222 num_subbuf_alloc
= chanb
->num_subbuf
;
223 if (chanb
->extra_reader_sb
)
226 for (i
= 0; i
< chanb
->num_subbuf
; i
++)
227 bufb
->buf_wsb
[i
].id
= subbuffer_id(config
, 0, 1, i
);
228 if (chanb
->extra_reader_sb
)
229 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1,
230 num_subbuf_alloc
- 1);
232 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1, 0);
234 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
235 /* Don't reset mmap_offset */
236 v_set(config
, &bufb
->array
[i
]->records_commit
, 0);
237 v_set(config
, &bufb
->array
[i
]->records_unread
, 0);
238 bufb
->array
[i
]->data_size
= 0;
239 /* Don't reset backend page and virt addresses */
241 /* Don't reset num_pages_per_subbuf, cpu, allocated */
242 v_set(config
, &bufb
->records_read
, 0);
246 * The frontend is responsible for also calling ring_buffer_backend_reset for
247 * each buffer when calling channel_backend_reset.
249 void channel_backend_reset(struct channel_backend
*chanb
)
251 struct lttng_kernel_ring_buffer_channel
*chan
= container_of(chanb
, struct lttng_kernel_ring_buffer_channel
, backend
);
252 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
255 * Don't reset buf_size, subbuf_size, subbuf_size_order,
256 * num_subbuf_order, buf_size_order, extra_reader_sb, num_subbuf,
257 * priv, notifiers, config, cpumask and name.
259 chanb
->start_tsc
= config
->cb
.ring_buffer_clock_read(chan
);
262 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0))
265 * No need to implement a "dead" callback to do a buffer switch here,
266 * because it will happen when tracing is stopped, or will be done by
267 * switch timer CPU DEAD callback.
268 * We don't free buffers when CPU go away, because it would make trace
269 * data vanish, which is unwanted.
271 int lttng_cpuhp_rb_backend_prepare(unsigned int cpu
,
272 struct lttng_cpuhp_node
*node
)
274 struct channel_backend
*chanb
= container_of(node
,
275 struct channel_backend
, cpuhp_prepare
);
276 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
277 struct lttng_kernel_ring_buffer
*buf
;
280 CHAN_WARN_ON(chanb
, config
->alloc
== RING_BUFFER_ALLOC_GLOBAL
);
282 buf
= per_cpu_ptr(chanb
->buf
, cpu
);
283 ret
= lib_ring_buffer_create(buf
, chanb
, cpu
);
286 "LTTng: ring_buffer_cpu_hp_callback: cpu %d "
287 "buffer creation failed\n", cpu
);
292 EXPORT_SYMBOL_GPL(lttng_cpuhp_rb_backend_prepare
);
294 #else /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
296 #ifdef CONFIG_HOTPLUG_CPU
299 * lib_ring_buffer_cpu_hp_callback - CPU hotplug callback
300 * @nb: notifier block
301 * @action: hotplug action to take
304 * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
307 int lib_ring_buffer_cpu_hp_callback(struct notifier_block
*nb
,
308 unsigned long action
,
311 unsigned int cpu
= (unsigned long)hcpu
;
312 struct channel_backend
*chanb
= container_of(nb
, struct channel_backend
,
314 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
315 struct lttng_kernel_ring_buffer
*buf
;
318 CHAN_WARN_ON(chanb
, config
->alloc
== RING_BUFFER_ALLOC_GLOBAL
);
322 case CPU_UP_PREPARE_FROZEN
:
323 buf
= per_cpu_ptr(chanb
->buf
, cpu
);
324 ret
= lib_ring_buffer_create(buf
, chanb
, cpu
);
327 "LTTng: ring_buffer_cpu_hp_callback: cpu %d "
328 "buffer creation failed\n", cpu
);
333 case CPU_DEAD_FROZEN
:
334 /* No need to do a buffer switch here, because it will happen
335 * when tracing is stopped, or will be done by switch timer CPU
344 #endif /* #else #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
347 * channel_backend_init - initialize a channel backend
348 * @chanb: channel backend
349 * @name: channel name
350 * @config: client ring buffer configuration
351 * @priv: client private data
352 * @parent: dentry of parent directory, %NULL for root directory
353 * @subbuf_size: size of sub-buffers (> PAGE_SIZE, power of 2)
354 * @num_subbuf: number of sub-buffers (power of 2)
356 * Returns channel pointer if successful, %NULL otherwise.
358 * Creates per-cpu channel buffers using the sizes and attributes
359 * specified. The created channel buffer files will be named
360 * name_0...name_N-1. File permissions will be %S_IRUSR.
362 * Called with CPU hotplug disabled.
364 int channel_backend_init(struct channel_backend
*chanb
,
366 const struct lttng_kernel_ring_buffer_config
*config
,
367 void *priv
, size_t subbuf_size
, size_t num_subbuf
)
369 struct lttng_kernel_ring_buffer_channel
*chan
= container_of(chanb
, struct lttng_kernel_ring_buffer_channel
, backend
);
376 /* Check that the subbuffer size is larger than a page. */
377 if (subbuf_size
< PAGE_SIZE
)
381 * Make sure the number of subbuffers and subbuffer size are
382 * power of 2 and nonzero.
384 if (!subbuf_size
|| (subbuf_size
& (subbuf_size
- 1)))
386 if (!num_subbuf
|| (num_subbuf
& (num_subbuf
- 1)))
389 * Overwrite mode buffers require at least 2 subbuffers per
392 if (config
->mode
== RING_BUFFER_OVERWRITE
&& num_subbuf
< 2)
395 ret
= subbuffer_id_check_index(config
, num_subbuf
);
400 chanb
->buf_size
= num_subbuf
* subbuf_size
;
401 chanb
->subbuf_size
= subbuf_size
;
402 chanb
->buf_size_order
= get_count_order(chanb
->buf_size
);
403 chanb
->subbuf_size_order
= get_count_order(subbuf_size
);
404 chanb
->num_subbuf_order
= get_count_order(num_subbuf
);
405 chanb
->extra_reader_sb
=
406 (config
->mode
== RING_BUFFER_OVERWRITE
) ? 1 : 0;
407 chanb
->num_subbuf
= num_subbuf
;
408 strlcpy(chanb
->name
, name
, NAME_MAX
);
409 memcpy(&chanb
->config
, config
, sizeof(chanb
->config
));
411 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
412 if (!zalloc_cpumask_var(&chanb
->cpumask
, GFP_KERNEL
))
416 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
417 /* Allocating the buffer per-cpu structures */
418 chanb
->buf
= alloc_percpu(struct lttng_kernel_ring_buffer
);
422 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0))
423 chanb
->cpuhp_prepare
.component
= LTTNG_RING_BUFFER_BACKEND
;
424 ret
= cpuhp_state_add_instance(lttng_rb_hp_prepare
,
425 &chanb
->cpuhp_prepare
.node
);
428 #else /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
432 * In case of non-hotplug cpu, if the ring-buffer is allocated
433 * in early initcall, it will not be notified of secondary cpus.
434 * In that off case, we need to allocate for all possible cpus.
436 #ifdef CONFIG_HOTPLUG_CPU
438 * buf->backend.allocated test takes care of concurrent CPU
440 * Priority higher than frontend, so we create the ring buffer
441 * before we start the timer.
443 chanb
->cpu_hp_notifier
.notifier_call
=
444 lib_ring_buffer_cpu_hp_callback
;
445 chanb
->cpu_hp_notifier
.priority
= 5;
446 register_hotcpu_notifier(&chanb
->cpu_hp_notifier
);
449 for_each_online_cpu(i
) {
450 ret
= lib_ring_buffer_create(per_cpu_ptr(chanb
->buf
, i
),
453 goto free_bufs
; /* cpu hotplug locked */
457 for_each_possible_cpu(i
) {
458 ret
= lib_ring_buffer_create(per_cpu_ptr(chanb
->buf
, i
),
465 #endif /* #else #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
467 chanb
->buf
= kzalloc(sizeof(struct lttng_kernel_ring_buffer
), GFP_KERNEL
);
470 ret
= lib_ring_buffer_create(chanb
->buf
, chanb
, -1);
474 chanb
->start_tsc
= config
->cb
.ring_buffer_clock_read(chan
);
479 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
480 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0))
482 * Teardown of lttng_rb_hp_prepare instance
483 * on "add" error is handled within cpu hotplug,
484 * no teardown to do from the caller.
486 #else /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
487 #ifdef CONFIG_HOTPLUG_CPU
489 unregister_hotcpu_notifier(&chanb
->cpu_hp_notifier
);
491 #endif /* #else #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
492 for_each_possible_cpu(i
) {
493 struct lttng_kernel_ring_buffer
*buf
=
494 per_cpu_ptr(chanb
->buf
, i
);
496 if (!buf
->backend
.allocated
)
498 lib_ring_buffer_free(buf
);
500 free_percpu(chanb
->buf
);
504 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
)
505 free_cpumask_var(chanb
->cpumask
);
510 * channel_backend_unregister_notifiers - unregister notifiers
515 void channel_backend_unregister_notifiers(struct channel_backend
*chanb
)
517 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
519 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
520 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0))
523 ret
= cpuhp_state_remove_instance(lttng_rb_hp_prepare
,
524 &chanb
->cpuhp_prepare
.node
);
526 #else /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
527 unregister_hotcpu_notifier(&chanb
->cpu_hp_notifier
);
528 #endif /* #else #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
533 * channel_backend_free - destroy the channel
536 * Destroy all channel buffers and frees the channel.
538 void channel_backend_free(struct channel_backend
*chanb
)
540 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
543 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
544 for_each_possible_cpu(i
) {
545 struct lttng_kernel_ring_buffer
*buf
= per_cpu_ptr(chanb
->buf
, i
);
547 if (!buf
->backend
.allocated
)
549 lib_ring_buffer_free(buf
);
551 free_cpumask_var(chanb
->cpumask
);
552 free_percpu(chanb
->buf
);
554 struct lttng_kernel_ring_buffer
*buf
= chanb
->buf
;
556 CHAN_WARN_ON(chanb
, !buf
->backend
.allocated
);
557 lib_ring_buffer_free(buf
);
563 * lib_ring_buffer_write - write data to a ring_buffer buffer.
564 * @bufb : buffer backend
565 * @offset : offset within the buffer
566 * @src : source address
567 * @len : length to write
568 * @pagecpy : page size copied so far
570 void _lib_ring_buffer_write(struct lttng_kernel_ring_buffer_backend
*bufb
, size_t offset
,
571 const void *src
, size_t len
, size_t pagecpy
)
573 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
574 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
576 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
577 unsigned long sb_bindex
, id
;
583 sbidx
= offset
>> chanb
->subbuf_size_order
;
584 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
587 * Underlying layer should never ask for writes across
590 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
592 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
593 id
= bufb
->buf_wsb
[sbidx
].id
;
594 sb_bindex
= subbuffer_id_get_index(config
, id
);
595 rpages
= bufb
->array
[sb_bindex
];
596 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
597 && subbuffer_id_is_noref(config
, id
));
598 lib_ring_buffer_do_copy(config
,
599 rpages
->p
[index
].virt
600 + (offset
& ~PAGE_MASK
),
602 } while (unlikely(len
!= pagecpy
));
604 EXPORT_SYMBOL_GPL(_lib_ring_buffer_write
);
608 * lib_ring_buffer_memset - write len bytes of c to a ring_buffer buffer.
609 * @bufb : buffer backend
610 * @offset : offset within the buffer
611 * @c : the byte to write
612 * @len : length to write
613 * @pagecpy : page size copied so far
615 void _lib_ring_buffer_memset(struct lttng_kernel_ring_buffer_backend
*bufb
,
617 int c
, size_t len
, size_t pagecpy
)
619 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
620 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
622 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
623 unsigned long sb_bindex
, id
;
628 sbidx
= offset
>> chanb
->subbuf_size_order
;
629 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
632 * Underlying layer should never ask for writes across
635 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
637 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
638 id
= bufb
->buf_wsb
[sbidx
].id
;
639 sb_bindex
= subbuffer_id_get_index(config
, id
);
640 rpages
= bufb
->array
[sb_bindex
];
641 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
642 && subbuffer_id_is_noref(config
, id
));
643 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
644 + (offset
& ~PAGE_MASK
),
646 } while (unlikely(len
!= pagecpy
));
648 EXPORT_SYMBOL_GPL(_lib_ring_buffer_memset
);
651 * lib_ring_buffer_strcpy - write string data to a ring_buffer buffer.
652 * @bufb : buffer backend
653 * @offset : offset within the buffer
654 * @src : source address
655 * @len : length to write
656 * @pagecpy : page size copied so far
657 * @pad : character to use for padding
659 void _lib_ring_buffer_strcpy(struct lttng_kernel_ring_buffer_backend
*bufb
,
660 size_t offset
, const char *src
, size_t len
,
661 size_t pagecpy
, int pad
)
663 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
664 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
666 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
667 unsigned long sb_bindex
, id
;
668 int src_terminated
= 0;
670 CHAN_WARN_ON(chanb
, !len
);
676 sbidx
= offset
>> chanb
->subbuf_size_order
;
677 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
680 * Underlying layer should never ask for writes across
683 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
685 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
686 id
= bufb
->buf_wsb
[sbidx
].id
;
687 sb_bindex
= subbuffer_id_get_index(config
, id
);
688 rpages
= bufb
->array
[sb_bindex
];
689 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
690 && subbuffer_id_is_noref(config
, id
));
692 if (likely(!src_terminated
)) {
693 size_t count
, to_copy
;
697 to_copy
--; /* Final '\0' */
698 count
= lib_ring_buffer_do_strcpy(config
,
699 rpages
->p
[index
].virt
700 + (offset
& ~PAGE_MASK
),
704 if (unlikely(count
< to_copy
)) {
705 size_t pad_len
= to_copy
- count
;
707 /* Next pages will have padding */
709 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
710 + (offset
& ~PAGE_MASK
),
719 pad_len
--; /* Final '\0' */
720 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
721 + (offset
& ~PAGE_MASK
),
725 } while (unlikely(len
!= pagecpy
));
727 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
),
730 EXPORT_SYMBOL_GPL(_lib_ring_buffer_strcpy
);
733 * _lib_ring_buffer_pstrcpy - write to a buffer backend P-string
734 * @bufb : buffer backend
735 * @src : source pointer to copy from
736 * @len : length of data to copy
737 * @pad : character to use for padding
739 * This function copies up to @len bytes of data from a source pointer
740 * to a Pascal String into the buffer backend. If a terminating '\0'
741 * character is found in @src before @len characters are copied, pad the
742 * buffer with @pad characters (e.g. '\0').
744 * The length of the pascal strings in the ring buffer is explicit: it
745 * is either the array or sequence length.
747 void _lib_ring_buffer_pstrcpy(struct lttng_kernel_ring_buffer_backend
*bufb
,
748 size_t offset
, const char *src
, size_t len
, int pad
)
750 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
751 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
752 size_t sbidx
, index
, bytes_left_in_page
;
753 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
754 unsigned long sb_bindex
, id
;
755 bool src_terminated
= false;
757 CHAN_WARN_ON(chanb
, !len
);
759 sbidx
= offset
>> chanb
->subbuf_size_order
;
760 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
763 * Underlying layer should never ask for writes across
766 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
768 bytes_left_in_page
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
769 id
= bufb
->buf_wsb
[sbidx
].id
;
770 sb_bindex
= subbuffer_id_get_index(config
, id
);
771 rpages
= bufb
->array
[sb_bindex
];
772 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
773 && subbuffer_id_is_noref(config
, id
));
775 if (likely(!src_terminated
)) {
776 size_t count
, to_copy
;
778 to_copy
= bytes_left_in_page
;
779 count
= lib_ring_buffer_do_strcpy(config
,
780 rpages
->p
[index
].virt
781 + (offset
& ~PAGE_MASK
),
785 if (unlikely(count
< to_copy
)) {
786 size_t pad_len
= to_copy
- count
;
788 /* Next pages will have padding */
789 src_terminated
= true;
790 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
791 + (offset
& ~PAGE_MASK
),
798 pad_len
= bytes_left_in_page
;
799 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
800 + (offset
& ~PAGE_MASK
),
804 len
-= bytes_left_in_page
;
806 src
+= bytes_left_in_page
;
807 } while (unlikely(len
));
809 EXPORT_SYMBOL_GPL(_lib_ring_buffer_pstrcpy
);
812 * lib_ring_buffer_copy_from_user_inatomic - write user data to a ring_buffer buffer.
813 * @bufb : buffer backend
814 * @offset : offset within the buffer
815 * @src : source address
816 * @len : length to write
817 * @pagecpy : page size copied so far
819 * This function deals with userspace pointers, it should never be called
820 * directly without having the src pointer checked with access_ok()
823 void _lib_ring_buffer_copy_from_user_inatomic(struct lttng_kernel_ring_buffer_backend
*bufb
,
825 const void __user
*src
, size_t len
,
828 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
829 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
831 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
832 unsigned long sb_bindex
, id
;
839 sbidx
= offset
>> chanb
->subbuf_size_order
;
840 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
843 * Underlying layer should never ask for writes across
846 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
848 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
849 id
= bufb
->buf_wsb
[sbidx
].id
;
850 sb_bindex
= subbuffer_id_get_index(config
, id
);
851 rpages
= bufb
->array
[sb_bindex
];
852 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
853 && subbuffer_id_is_noref(config
, id
));
854 ret
= lib_ring_buffer_do_copy_from_user_inatomic(rpages
->p
[index
].virt
855 + (offset
& ~PAGE_MASK
),
859 _lib_ring_buffer_memset(bufb
, offset
, 0, len
, 0);
860 break; /* stop copy */
862 } while (unlikely(len
!= pagecpy
));
864 EXPORT_SYMBOL_GPL(_lib_ring_buffer_copy_from_user_inatomic
);
867 * lib_ring_buffer_strcpy_from_user_inatomic - write userspace string data to a ring_buffer buffer.
868 * @bufb : buffer backend
869 * @offset : offset within the buffer
870 * @src : source address
871 * @len : length to write
872 * @pagecpy : page size copied so far
873 * @pad : character to use for padding
875 * This function deals with userspace pointers, it should never be called
876 * directly without having the src pointer checked with access_ok()
879 void _lib_ring_buffer_strcpy_from_user_inatomic(struct lttng_kernel_ring_buffer_backend
*bufb
,
880 size_t offset
, const char __user
*src
, size_t len
,
881 size_t pagecpy
, int pad
)
883 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
884 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
886 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
887 unsigned long sb_bindex
, id
;
888 int src_terminated
= 0;
895 sbidx
= offset
>> chanb
->subbuf_size_order
;
896 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
899 * Underlying layer should never ask for writes across
902 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
904 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
905 id
= bufb
->buf_wsb
[sbidx
].id
;
906 sb_bindex
= subbuffer_id_get_index(config
, id
);
907 rpages
= bufb
->array
[sb_bindex
];
908 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
909 && subbuffer_id_is_noref(config
, id
));
911 if (likely(!src_terminated
)) {
912 size_t count
, to_copy
;
916 to_copy
--; /* Final '\0' */
917 count
= lib_ring_buffer_do_strcpy_from_user_inatomic(config
,
918 rpages
->p
[index
].virt
919 + (offset
& ~PAGE_MASK
),
923 if (unlikely(count
< to_copy
)) {
924 size_t pad_len
= to_copy
- count
;
926 /* Next pages will have padding */
928 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
929 + (offset
& ~PAGE_MASK
),
938 pad_len
--; /* Final '\0' */
939 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
940 + (offset
& ~PAGE_MASK
),
944 } while (unlikely(len
!= pagecpy
));
946 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
),
949 EXPORT_SYMBOL_GPL(_lib_ring_buffer_strcpy_from_user_inatomic
);
952 * _lib_ring_buffer_pstrcpy_from_user_inatomic - write userspace string to a buffer backend P-string
953 * @bufb : buffer backend
954 * @src : source pointer to copy from
955 * @len : length of data to copy
956 * @pad : character to use for padding
958 * This function copies up to @len bytes of data from a source pointer
959 * to a Pascal String into the buffer backend. If a terminating '\0'
960 * character is found in @src before @len characters are copied, pad the
961 * buffer with @pad characters (e.g. '\0').
963 * The length of the pascal strings in the ring buffer is explicit: it
964 * is either the array or sequence length.
966 * This function deals with userspace pointers, it should never be called
967 * directly without having the src pointer checked with access_ok()
970 void _lib_ring_buffer_pstrcpy_from_user_inatomic(struct lttng_kernel_ring_buffer_backend
*bufb
,
971 size_t offset
, const char __user
*src
, size_t len
, int pad
)
973 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
974 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
975 size_t sbidx
, index
, bytes_left_in_page
;
976 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
977 unsigned long sb_bindex
, id
;
978 bool src_terminated
= false;
980 CHAN_WARN_ON(chanb
, !len
);
982 sbidx
= offset
>> chanb
->subbuf_size_order
;
983 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
986 * Underlying layer should never ask for writes across
989 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
991 bytes_left_in_page
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
992 id
= bufb
->buf_wsb
[sbidx
].id
;
993 sb_bindex
= subbuffer_id_get_index(config
, id
);
994 rpages
= bufb
->array
[sb_bindex
];
995 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
996 && subbuffer_id_is_noref(config
, id
));
998 if (likely(!src_terminated
)) {
999 size_t count
, to_copy
;
1001 to_copy
= bytes_left_in_page
;
1002 count
= lib_ring_buffer_do_strcpy_from_user_inatomic(config
,
1003 rpages
->p
[index
].virt
1004 + (offset
& ~PAGE_MASK
),
1008 if (unlikely(count
< to_copy
)) {
1009 size_t pad_len
= to_copy
- count
;
1011 /* Next pages will have padding */
1012 src_terminated
= true;
1013 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
1014 + (offset
& ~PAGE_MASK
),
1021 pad_len
= bytes_left_in_page
;
1022 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
1023 + (offset
& ~PAGE_MASK
),
1027 len
-= bytes_left_in_page
;
1028 if (!src_terminated
)
1029 src
+= bytes_left_in_page
;
1030 } while (unlikely(len
));
1032 EXPORT_SYMBOL_GPL(_lib_ring_buffer_pstrcpy_from_user_inatomic
);
1035 * lib_ring_buffer_read - read data from ring_buffer_buffer.
1036 * @bufb : buffer backend
1037 * @offset : offset within the buffer
1038 * @dest : destination address
1039 * @len : length to copy to destination
1041 * Should be protected by get_subbuf/put_subbuf.
1042 * Returns the length copied.
1044 size_t lib_ring_buffer_read(struct lttng_kernel_ring_buffer_backend
*bufb
, size_t offset
,
1045 void *dest
, size_t len
)
1047 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1048 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1049 size_t index
, pagecpy
, orig_len
;
1050 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1051 unsigned long sb_bindex
, id
;
1054 offset
&= chanb
->buf_size
- 1;
1055 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1059 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
1060 id
= bufb
->buf_rsb
.id
;
1061 sb_bindex
= subbuffer_id_get_index(config
, id
);
1062 rpages
= bufb
->array
[sb_bindex
];
1063 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1064 && subbuffer_id_is_noref(config
, id
));
1065 memcpy(dest
, rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
),
1072 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1074 * Underlying layer should never ask for reads across
1077 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
1081 EXPORT_SYMBOL_GPL(lib_ring_buffer_read
);
1084 * __lib_ring_buffer_copy_to_user - read data from ring_buffer to userspace
1085 * @bufb : buffer backend
1086 * @offset : offset within the buffer
1087 * @dest : destination userspace address
1088 * @len : length to copy to destination
1090 * Should be protected by get_subbuf/put_subbuf.
1091 * access_ok() must have been performed on dest addresses prior to call this
1093 * Returns -EFAULT on error, 0 if ok.
1095 int __lib_ring_buffer_copy_to_user(struct lttng_kernel_ring_buffer_backend
*bufb
,
1096 size_t offset
, void __user
*dest
, size_t len
)
1098 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1099 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1102 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1103 unsigned long sb_bindex
, id
;
1105 offset
&= chanb
->buf_size
- 1;
1106 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1110 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
1111 id
= bufb
->buf_rsb
.id
;
1112 sb_bindex
= subbuffer_id_get_index(config
, id
);
1113 rpages
= bufb
->array
[sb_bindex
];
1114 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1115 && subbuffer_id_is_noref(config
, id
));
1116 if (__copy_to_user(dest
,
1117 rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
),
1125 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1127 * Underlying layer should never ask for reads across
1130 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
1134 EXPORT_SYMBOL_GPL(__lib_ring_buffer_copy_to_user
);
1137 * lib_ring_buffer_read_cstr - read a C-style string from ring_buffer.
1138 * @bufb : buffer backend
1139 * @offset : offset within the buffer
1140 * @dest : destination address
1141 * @len : destination's length
1143 * Return string's length, or -EINVAL on error.
1144 * Should be protected by get_subbuf/put_subbuf.
1145 * Destination length should be at least 1 to hold '\0'.
1147 int lib_ring_buffer_read_cstr(struct lttng_kernel_ring_buffer_backend
*bufb
, size_t offset
,
1148 void *dest
, size_t len
)
1150 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1151 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1153 ssize_t pagecpy
, pagelen
, strpagelen
, orig_offset
;
1155 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1156 unsigned long sb_bindex
, id
;
1158 offset
&= chanb
->buf_size
- 1;
1159 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1160 orig_offset
= offset
;
1164 id
= bufb
->buf_rsb
.id
;
1165 sb_bindex
= subbuffer_id_get_index(config
, id
);
1166 rpages
= bufb
->array
[sb_bindex
];
1167 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1168 && subbuffer_id_is_noref(config
, id
));
1169 str
= (char *)rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
);
1170 pagelen
= PAGE_SIZE
- (offset
& ~PAGE_MASK
);
1171 strpagelen
= strnlen(str
, pagelen
);
1173 pagecpy
= min_t(size_t, len
, strpagelen
);
1175 memcpy(dest
, str
, pagecpy
);
1180 offset
+= strpagelen
;
1181 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1182 if (strpagelen
< pagelen
)
1185 * Underlying layer should never ask for reads across
1188 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
1191 ((char *)dest
)[0] = 0;
1192 return offset
- orig_offset
;
1194 EXPORT_SYMBOL_GPL(lib_ring_buffer_read_cstr
);
1197 * lib_ring_buffer_read_get_pfn - Get a page frame number to read from
1198 * @bufb : buffer backend
1199 * @offset : offset within the buffer
1200 * @virt : pointer to page address (output)
1202 * Should be protected by get_subbuf/put_subbuf.
1203 * Returns the pointer to the page frame number unsigned long.
1205 unsigned long *lib_ring_buffer_read_get_pfn(struct lttng_kernel_ring_buffer_backend
*bufb
,
1206 size_t offset
, void ***virt
)
1209 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1210 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1211 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1212 unsigned long sb_bindex
, id
;
1214 offset
&= chanb
->buf_size
- 1;
1215 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1216 id
= bufb
->buf_rsb
.id
;
1217 sb_bindex
= subbuffer_id_get_index(config
, id
);
1218 rpages
= bufb
->array
[sb_bindex
];
1219 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1220 && subbuffer_id_is_noref(config
, id
));
1221 *virt
= &rpages
->p
[index
].virt
;
1222 return &rpages
->p
[index
].pfn
;
1224 EXPORT_SYMBOL_GPL(lib_ring_buffer_read_get_pfn
);
1227 * lib_ring_buffer_read_offset_address - get address of a buffer location
1228 * @bufb : buffer backend
1229 * @offset : offset within the buffer.
1231 * Return the address where a given offset is located (for read).
1232 * Should be used to get the current subbuffer header pointer. Given we know
1233 * it's never on a page boundary, it's safe to read/write directly
1234 * from/to this address, as long as the read/write is never bigger than a
1237 void *lib_ring_buffer_read_offset_address(struct lttng_kernel_ring_buffer_backend
*bufb
,
1241 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1242 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1243 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1244 unsigned long sb_bindex
, id
;
1246 offset
&= chanb
->buf_size
- 1;
1247 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1248 id
= bufb
->buf_rsb
.id
;
1249 sb_bindex
= subbuffer_id_get_index(config
, id
);
1250 rpages
= bufb
->array
[sb_bindex
];
1251 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1252 && subbuffer_id_is_noref(config
, id
));
1253 return rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
);
1255 EXPORT_SYMBOL_GPL(lib_ring_buffer_read_offset_address
);
1258 * lib_ring_buffer_offset_address - get address of a location within the buffer
1259 * @bufb : buffer backend
1260 * @offset : offset within the buffer.
1262 * Return the address where a given offset is located.
1263 * Should be used to get the current subbuffer header pointer. Given we know
1264 * it's always at the beginning of a page, it's safe to write directly to this
1265 * address, as long as the write is never bigger than a page size.
1267 void *lib_ring_buffer_offset_address(struct lttng_kernel_ring_buffer_backend
*bufb
,
1270 size_t sbidx
, index
;
1271 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1272 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1273 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1274 unsigned long sb_bindex
, id
;
1276 offset
&= chanb
->buf_size
- 1;
1277 sbidx
= offset
>> chanb
->subbuf_size_order
;
1278 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1279 id
= bufb
->buf_wsb
[sbidx
].id
;
1280 sb_bindex
= subbuffer_id_get_index(config
, id
);
1281 rpages
= bufb
->array
[sb_bindex
];
1282 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1283 && subbuffer_id_is_noref(config
, id
));
1284 return rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
);
1286 EXPORT_SYMBOL_GPL(lib_ring_buffer_offset_address
);