diff options
Diffstat (limited to 'kernel/trace/ring_buffer.c')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 1662 |
1 files changed, 1289 insertions, 373 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index cebd879a30cb..43460949ad3f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -31,6 +31,9 @@ #include <asm/local64.h> #include <asm/local.h> +#include <asm/setup.h> + +#include "trace.h" /* * The "absolute" timestamp in the buffer is only 59 bits. @@ -42,6 +45,24 @@ static void update_pages_handler(struct work_struct *work); +#define RING_BUFFER_META_MAGIC 0xBADFEED + +struct ring_buffer_meta { + int magic; + int struct_sizes; + unsigned long total_size; + unsigned long buffers_offset; +}; + +struct ring_buffer_cpu_meta { + unsigned long first_buffer; + unsigned long head_buffer; + unsigned long commit_buffer; + __u32 subbuf_size; + __u32 nr_subbufs; + int buffers[]; +}; + /* * The ring buffer header is special. We must manually up keep it. */ @@ -342,7 +363,8 @@ struct buffer_page { local_t entries; /* entries on this page */ unsigned long real_end; /* real end of data */ unsigned order; /* order of the page */ - u32 id; /* ID for external mapping */ + u32 id:30; /* ID for external mapping */ + u32 range:1; /* Mapped via a range */ struct buffer_data_page *page; /* Actual data page */ }; @@ -373,7 +395,9 @@ static __always_inline unsigned int rb_page_commit(struct buffer_page *bpage) static void free_buffer_page(struct buffer_page *bpage) { - free_pages((unsigned long)bpage->page, bpage->order); + /* Range pages are not to be freed */ + if (!bpage->range) + free_pages((unsigned long)bpage->page, bpage->order); kfree(bpage); } @@ -462,6 +486,8 @@ struct ring_buffer_per_cpu { unsigned long nr_pages; unsigned int current_context; struct list_head *pages; + /* pages generation counter, incremented when the list changes */ + unsigned long cnt; struct buffer_page *head_page; /* read from head */ struct buffer_page *tail_page; /* write to tail */ struct buffer_page *commit_page; /* committed pages */ @@ -491,9 +517,11 @@ struct ring_buffer_per_cpu { unsigned long pages_removed; unsigned int mapped; + unsigned int user_mapped; /* user space mapping */ struct mutex mapping_lock; unsigned long *subbuf_ids; /* ID to subbuf VA */ struct trace_buffer_meta *meta_page; + struct ring_buffer_cpu_meta *ring_meta; /* ring buffer pages to update, > 0 to add, < 0 to remove */ long nr_pages_to_update; @@ -523,6 +551,11 @@ struct trace_buffer { struct rb_irq_work irq_work; bool time_stamp_abs; + unsigned long range_addr_start; + unsigned long range_addr_end; + + struct ring_buffer_meta *meta; + unsigned int subbuf_size; unsigned int subbuf_order; unsigned int max_data_size; @@ -1239,6 +1272,11 @@ static void rb_head_page_activate(struct ring_buffer_per_cpu *cpu_buffer) * Set the previous list pointer to have the HEAD flag. */ rb_set_list_to_head(head->list.prev); + + if (cpu_buffer->ring_meta) { + struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; + meta->head_buffer = (unsigned long)head->page; + } } static void rb_list_head_clear(struct list_head *list) @@ -1320,6 +1358,13 @@ static inline void rb_inc_page(struct buffer_page **bpage) *bpage = list_entry(p, struct buffer_page, list); } +static inline void rb_dec_page(struct buffer_page **bpage) +{ + struct list_head *p = rb_list_head((*bpage)->list.prev); + + *bpage = list_entry(p, struct buffer_page, list); +} + static struct buffer_page * rb_set_head_page(struct ring_buffer_per_cpu *cpu_buffer) { @@ -1442,45 +1487,721 @@ static void rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer, RB_WARN_ON(cpu_buffer, val & RB_FLAG_MASK); } +static bool rb_check_links(struct ring_buffer_per_cpu *cpu_buffer, + struct list_head *list) +{ + if (RB_WARN_ON(cpu_buffer, + rb_list_head(rb_list_head(list->next)->prev) != list)) + return false; + + if (RB_WARN_ON(cpu_buffer, + rb_list_head(rb_list_head(list->prev)->next) != list)) + return false; + + return true; +} + /** * rb_check_pages - integrity check of buffer pages * @cpu_buffer: CPU buffer with pages to test * * As a safety measure we check to make sure the data pages have not * been corrupted. - * - * Callers of this function need to guarantee that the list of pages doesn't get - * modified during the check. In particular, if it's possible that the function - * is invoked with concurrent readers which can swap in a new reader page then - * the caller should take cpu_buffer->reader_lock. */ static void rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) { - struct list_head *head = rb_list_head(cpu_buffer->pages); - struct list_head *tmp; + struct list_head *head, *tmp; + unsigned long buffer_cnt; + unsigned long flags; + int nr_loops = 0; - if (RB_WARN_ON(cpu_buffer, - rb_list_head(rb_list_head(head->next)->prev) != head)) + /* + * Walk the linked list underpinning the ring buffer and validate all + * its next and prev links. + * + * The check acquires the reader_lock to avoid concurrent processing + * with code that could be modifying the list. However, the lock cannot + * be held for the entire duration of the walk, as this would make the + * time when interrupts are disabled non-deterministic, dependent on the + * ring buffer size. Therefore, the code releases and re-acquires the + * lock after checking each page. The ring_buffer_per_cpu.cnt variable + * is then used to detect if the list was modified while the lock was + * not held, in which case the check needs to be restarted. + * + * The code attempts to perform the check at most three times before + * giving up. This is acceptable because this is only a self-validation + * to detect problems early on. In practice, the list modification + * operations are fairly spaced, and so this check typically succeeds at + * most on the second try. + */ +again: + if (++nr_loops > 3) return; - if (RB_WARN_ON(cpu_buffer, - rb_list_head(rb_list_head(head->prev)->next) != head)) + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + head = rb_list_head(cpu_buffer->pages); + if (!rb_check_links(cpu_buffer, head)) + goto out_locked; + buffer_cnt = cpu_buffer->cnt; + tmp = head; + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + + while (true) { + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + + if (buffer_cnt != cpu_buffer->cnt) { + /* The list was updated, try again. */ + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + goto again; + } + + tmp = rb_list_head(tmp->next); + if (tmp == head) + /* The iteration circled back, all is done. */ + goto out_locked; + + if (!rb_check_links(cpu_buffer, tmp)) + goto out_locked; + + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + } + +out_locked: + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); +} + +/* + * Take an address, add the meta data size as well as the array of + * array subbuffer indexes, then align it to a subbuffer size. + * + * This is used to help find the next per cpu subbuffer within a mapped range. + */ +static unsigned long +rb_range_align_subbuf(unsigned long addr, int subbuf_size, int nr_subbufs) +{ + addr += sizeof(struct ring_buffer_cpu_meta) + + sizeof(int) * nr_subbufs; + return ALIGN(addr, subbuf_size); +} + +/* + * Return the ring_buffer_meta for a given @cpu. + */ +static void *rb_range_meta(struct trace_buffer *buffer, int nr_pages, int cpu) +{ + int subbuf_size = buffer->subbuf_size + BUF_PAGE_HDR_SIZE; + struct ring_buffer_cpu_meta *meta; + struct ring_buffer_meta *bmeta; + unsigned long ptr; + int nr_subbufs; + + bmeta = buffer->meta; + if (!bmeta) + return NULL; + + ptr = (unsigned long)bmeta + bmeta->buffers_offset; + meta = (struct ring_buffer_cpu_meta *)ptr; + + /* When nr_pages passed in is zero, the first meta has already been initialized */ + if (!nr_pages) { + nr_subbufs = meta->nr_subbufs; + } else { + /* Include the reader page */ + nr_subbufs = nr_pages + 1; + } + + /* + * The first chunk may not be subbuffer aligned, where as + * the rest of the chunks are. + */ + if (cpu) { + ptr = rb_range_align_subbuf(ptr, subbuf_size, nr_subbufs); + ptr += subbuf_size * nr_subbufs; + + /* We can use multiplication to find chunks greater than 1 */ + if (cpu > 1) { + unsigned long size; + unsigned long p; + + /* Save the beginning of this CPU chunk */ + p = ptr; + ptr = rb_range_align_subbuf(ptr, subbuf_size, nr_subbufs); + ptr += subbuf_size * nr_subbufs; + + /* Now all chunks after this are the same size */ + size = ptr - p; + ptr += size * (cpu - 2); + } + } + return (void *)ptr; +} + +/* Return the start of subbufs given the meta pointer */ +static void *rb_subbufs_from_meta(struct ring_buffer_cpu_meta *meta) +{ + int subbuf_size = meta->subbuf_size; + unsigned long ptr; + + ptr = (unsigned long)meta; + ptr = rb_range_align_subbuf(ptr, subbuf_size, meta->nr_subbufs); + + return (void *)ptr; +} + +/* + * Return a specific sub-buffer for a given @cpu defined by @idx. + */ +static void *rb_range_buffer(struct ring_buffer_per_cpu *cpu_buffer, int idx) +{ + struct ring_buffer_cpu_meta *meta; + unsigned long ptr; + int subbuf_size; + + meta = rb_range_meta(cpu_buffer->buffer, 0, cpu_buffer->cpu); + if (!meta) + return NULL; + + if (WARN_ON_ONCE(idx >= meta->nr_subbufs)) + return NULL; + + subbuf_size = meta->subbuf_size; + + /* Map this buffer to the order that's in meta->buffers[] */ + idx = meta->buffers[idx]; + + ptr = (unsigned long)rb_subbufs_from_meta(meta); + + ptr += subbuf_size * idx; + if (ptr + subbuf_size > cpu_buffer->buffer->range_addr_end) + return NULL; + + return (void *)ptr; +} + +/* + * See if the existing memory contains a valid meta section. + * if so, use that, otherwise initialize it. + */ +static bool rb_meta_init(struct trace_buffer *buffer, int scratch_size) +{ + unsigned long ptr = buffer->range_addr_start; + struct ring_buffer_meta *bmeta; + unsigned long total_size; + int struct_sizes; + + bmeta = (struct ring_buffer_meta *)ptr; + buffer->meta = bmeta; + + total_size = buffer->range_addr_end - buffer->range_addr_start; + + struct_sizes = sizeof(struct ring_buffer_cpu_meta); + struct_sizes |= sizeof(*bmeta) << 16; + + /* The first buffer will start word size after the meta page */ + ptr += sizeof(*bmeta); + ptr = ALIGN(ptr, sizeof(long)); + ptr += scratch_size; + + if (bmeta->magic != RING_BUFFER_META_MAGIC) { + pr_info("Ring buffer boot meta mismatch of magic\n"); + goto init; + } + + if (bmeta->struct_sizes != struct_sizes) { + pr_info("Ring buffer boot meta mismatch of struct size\n"); + goto init; + } + + if (bmeta->total_size != total_size) { + pr_info("Ring buffer boot meta mismatch of total size\n"); + goto init; + } + + if (bmeta->buffers_offset > bmeta->total_size) { + pr_info("Ring buffer boot meta mismatch of offset outside of total size\n"); + goto init; + } + + if (bmeta->buffers_offset != (void *)ptr - (void *)bmeta) { + pr_info("Ring buffer boot meta mismatch of first buffer offset\n"); + goto init; + } + + return true; + + init: + bmeta->magic = RING_BUFFER_META_MAGIC; + bmeta->struct_sizes = struct_sizes; + bmeta->total_size = total_size; + bmeta->buffers_offset = (void *)ptr - (void *)bmeta; + + /* Zero out the scatch pad */ + memset((void *)bmeta + sizeof(*bmeta), 0, bmeta->buffers_offset - sizeof(*bmeta)); + + return false; +} + +/* + * See if the existing memory contains valid ring buffer data. + * As the previous kernel must be the same as this kernel, all + * the calculations (size of buffers and number of buffers) + * must be the same. + */ +static bool rb_cpu_meta_valid(struct ring_buffer_cpu_meta *meta, int cpu, + struct trace_buffer *buffer, int nr_pages, + unsigned long *subbuf_mask) +{ + int subbuf_size = PAGE_SIZE; + struct buffer_data_page *subbuf; + unsigned long buffers_start; + unsigned long buffers_end; + int i; + + if (!subbuf_mask) + return false; + + buffers_start = meta->first_buffer; + buffers_end = meta->first_buffer + (subbuf_size * meta->nr_subbufs); + + /* Is the head and commit buffers within the range of buffers? */ + if (meta->head_buffer < buffers_start || + meta->head_buffer >= buffers_end) { + pr_info("Ring buffer boot meta [%d] head buffer out of range\n", cpu); + return false; + } + + if (meta->commit_buffer < buffers_start || + meta->commit_buffer >= buffers_end) { + pr_info("Ring buffer boot meta [%d] commit buffer out of range\n", cpu); + return false; + } + + subbuf = rb_subbufs_from_meta(meta); + + bitmap_clear(subbuf_mask, 0, meta->nr_subbufs); + + /* Is the meta buffers and the subbufs themselves have correct data? */ + for (i = 0; i < meta->nr_subbufs; i++) { + if (meta->buffers[i] < 0 || + meta->buffers[i] >= meta->nr_subbufs) { + pr_info("Ring buffer boot meta [%d] array out of range\n", cpu); + return false; + } + + if ((unsigned)local_read(&subbuf->commit) > subbuf_size) { + pr_info("Ring buffer boot meta [%d] buffer invalid commit\n", cpu); + return false; + } + + if (test_bit(meta->buffers[i], subbuf_mask)) { + pr_info("Ring buffer boot meta [%d] array has duplicates\n", cpu); + return false; + } + + set_bit(meta->buffers[i], subbuf_mask); + subbuf = (void *)subbuf + subbuf_size; + } + + return true; +} + +static int rb_meta_subbuf_idx(struct ring_buffer_cpu_meta *meta, void *subbuf); + +static int rb_read_data_buffer(struct buffer_data_page *dpage, int tail, int cpu, + unsigned long long *timestamp, u64 *delta_ptr) +{ + struct ring_buffer_event *event; + u64 ts, delta; + int events = 0; + int e; + + *delta_ptr = 0; + *timestamp = 0; + + ts = dpage->time_stamp; + + for (e = 0; e < tail; e += rb_event_length(event)) { + + event = (struct ring_buffer_event *)(dpage->data + e); + + switch (event->type_len) { + + case RINGBUF_TYPE_TIME_EXTEND: + delta = rb_event_time_stamp(event); + ts += delta; + break; + + case RINGBUF_TYPE_TIME_STAMP: + delta = rb_event_time_stamp(event); + delta = rb_fix_abs_ts(delta, ts); + if (delta < ts) { + *delta_ptr = delta; + *timestamp = ts; + return -1; + } + ts = delta; + break; + + case RINGBUF_TYPE_PADDING: + if (event->time_delta == 1) + break; + fallthrough; + case RINGBUF_TYPE_DATA: + events++; + ts += event->time_delta; + break; + + default: + return -1; + } + } + *timestamp = ts; + return events; +} + +static int rb_validate_buffer(struct buffer_data_page *dpage, int cpu) +{ + unsigned long long ts; + u64 delta; + int tail; + + tail = local_read(&dpage->commit); + return rb_read_data_buffer(dpage, tail, cpu, &ts, &delta); +} + +/* If the meta data has been validated, now validate the events */ +static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer) +{ + struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; + struct buffer_page *head_page, *orig_head; + unsigned long entry_bytes = 0; + unsigned long entries = 0; + int ret; + u64 ts; + int i; + + if (!meta || !meta->head_buffer) return; - for (tmp = rb_list_head(head->next); tmp != head; tmp = rb_list_head(tmp->next)) { - if (RB_WARN_ON(cpu_buffer, - rb_list_head(rb_list_head(tmp->next)->prev) != tmp)) - return; + /* Do the reader page first */ + ret = rb_validate_buffer(cpu_buffer->reader_page->page, cpu_buffer->cpu); + if (ret < 0) { + pr_info("Ring buffer reader page is invalid\n"); + goto invalid; + } + entries += ret; + entry_bytes += local_read(&cpu_buffer->reader_page->page->commit); + local_set(&cpu_buffer->reader_page->entries, ret); - if (RB_WARN_ON(cpu_buffer, - rb_list_head(rb_list_head(tmp->prev)->next) != tmp)) - return; + orig_head = head_page = cpu_buffer->head_page; + ts = head_page->page->time_stamp; + + /* + * Try to rewind the head so that we can read the pages which already + * read in the previous boot. + */ + if (head_page == cpu_buffer->tail_page) + goto skip_rewind; + + rb_dec_page(&head_page); + for (i = 0; i < meta->nr_subbufs + 1; i++, rb_dec_page(&head_page)) { + + /* Rewind until tail (writer) page. */ + if (head_page == cpu_buffer->tail_page) + break; + + /* Ensure the page has older data than head. */ + if (ts < head_page->page->time_stamp) + break; + + ts = head_page->page->time_stamp; + /* Ensure the page has correct timestamp and some data. */ + if (!ts || rb_page_commit(head_page) == 0) + break; + + /* Stop rewind if the page is invalid. */ + ret = rb_validate_buffer(head_page->page, cpu_buffer->cpu); + if (ret < 0) + break; + + /* Recover the number of entries and update stats. */ + local_set(&head_page->entries, ret); + if (ret) + local_inc(&cpu_buffer->pages_touched); + entries += ret; + entry_bytes += rb_page_commit(head_page); + } + if (i) + pr_info("Ring buffer [%d] rewound %d pages\n", cpu_buffer->cpu, i); + + /* The last rewound page must be skipped. */ + if (head_page != orig_head) + rb_inc_page(&head_page); + + /* + * If the ring buffer was rewound, then inject the reader page + * into the location just before the original head page. + */ + if (head_page != orig_head) { + struct buffer_page *bpage = orig_head; + + rb_dec_page(&bpage); + /* + * Insert the reader_page before the original head page. + * Since the list encode RB_PAGE flags, general list + * operations should be avoided. + */ + cpu_buffer->reader_page->list.next = &orig_head->list; + cpu_buffer->reader_page->list.prev = orig_head->list.prev; + orig_head->list.prev = &cpu_buffer->reader_page->list; + bpage->list.next = &cpu_buffer->reader_page->list; + + /* Make the head_page the reader page */ + cpu_buffer->reader_page = head_page; + bpage = head_page; + rb_inc_page(&head_page); + head_page->list.prev = bpage->list.prev; + rb_dec_page(&bpage); + bpage->list.next = &head_page->list; + rb_set_list_to_head(&bpage->list); + cpu_buffer->pages = &head_page->list; + + cpu_buffer->head_page = head_page; + meta->head_buffer = (unsigned long)head_page->page; + + /* Reset all the indexes */ + bpage = cpu_buffer->reader_page; + meta->buffers[0] = rb_meta_subbuf_idx(meta, bpage->page); + bpage->id = 0; + + for (i = 1, bpage = head_page; i < meta->nr_subbufs; + i++, rb_inc_page(&bpage)) { + meta->buffers[i] = rb_meta_subbuf_idx(meta, bpage->page); + bpage->id = i; + } + + /* We'll restart verifying from orig_head */ + head_page = orig_head; + } + + skip_rewind: + /* If the commit_buffer is the reader page, update the commit page */ + if (meta->commit_buffer == (unsigned long)cpu_buffer->reader_page->page) { + cpu_buffer->commit_page = cpu_buffer->reader_page; + /* Nothing more to do, the only page is the reader page */ + goto done; + } + + /* Iterate until finding the commit page */ + for (i = 0; i < meta->nr_subbufs + 1; i++, rb_inc_page(&head_page)) { + + /* Reader page has already been done */ + if (head_page == cpu_buffer->reader_page) + continue; + + ret = rb_validate_buffer(head_page->page, cpu_buffer->cpu); + if (ret < 0) { + pr_info("Ring buffer meta [%d] invalid buffer page\n", + cpu_buffer->cpu); + goto invalid; + } + + /* If the buffer has content, update pages_touched */ + if (ret) + local_inc(&cpu_buffer->pages_touched); + + entries += ret; + entry_bytes += local_read(&head_page->page->commit); + local_set(&cpu_buffer->head_page->entries, ret); + + if (head_page == cpu_buffer->commit_page) + break; + } + + if (head_page != cpu_buffer->commit_page) { + pr_info("Ring buffer meta [%d] commit page not found\n", + cpu_buffer->cpu); + goto invalid; + } + done: + local_set(&cpu_buffer->entries, entries); + local_set(&cpu_buffer->entries_bytes, entry_bytes); + + pr_info("Ring buffer meta [%d] is from previous boot!\n", cpu_buffer->cpu); + return; + + invalid: + /* The content of the buffers are invalid, reset the meta data */ + meta->head_buffer = 0; + meta->commit_buffer = 0; + + /* Reset the reader page */ + local_set(&cpu_buffer->reader_page->entries, 0); + local_set(&cpu_buffer->reader_page->page->commit, 0); + + /* Reset all the subbuffers */ + for (i = 0; i < meta->nr_subbufs - 1; i++, rb_inc_page(&head_page)) { + local_set(&head_page->entries, 0); + local_set(&head_page->page->commit, 0); + } +} + +static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages, int scratch_size) +{ + struct ring_buffer_cpu_meta *meta; + unsigned long *subbuf_mask; + unsigned long delta; + void *subbuf; + bool valid = false; + int cpu; + int i; + + /* Create a mask to test the subbuf array */ + subbuf_mask = bitmap_alloc(nr_pages + 1, GFP_KERNEL); + /* If subbuf_mask fails to allocate, then rb_meta_valid() will return false */ + + if (rb_meta_init(buffer, scratch_size)) + valid = true; + + for (cpu = 0; cpu < nr_cpu_ids; cpu++) { + void *next_meta; + + meta = rb_range_meta(buffer, nr_pages, cpu); + + if (valid && rb_cpu_meta_valid(meta, cpu, buffer, nr_pages, subbuf_mask)) { + /* Make the mappings match the current address */ + subbuf = rb_subbufs_from_meta(meta); + delta = (unsigned long)subbuf - meta->first_buffer; + meta->first_buffer += delta; + meta->head_buffer += delta; + meta->commit_buffer += delta; + continue; + } + + if (cpu < nr_cpu_ids - 1) + next_meta = rb_range_meta(buffer, nr_pages, cpu + 1); + else + next_meta = (void *)buffer->range_addr_end; + + memset(meta, 0, next_meta - (void *)meta); + + meta->nr_subbufs = nr_pages + 1; + meta->subbuf_size = PAGE_SIZE; + + subbuf = rb_subbufs_from_meta(meta); + + meta->first_buffer = (unsigned long)subbuf; + + /* + * The buffers[] array holds the order of the sub-buffers + * that are after the meta data. The sub-buffers may + * be swapped out when read and inserted into a different + * location of the ring buffer. Although their addresses + * remain the same, the buffers[] array contains the + * index into the sub-buffers holding their actual order. + */ + for (i = 0; i < meta->nr_subbufs; i++) { + meta->buffers[i] = i; + rb_init_page(subbuf); + subbuf += meta->subbuf_size; + } + } + bitmap_free(subbuf_mask); +} + +static void *rbm_start(struct seq_file *m, loff_t *pos) +{ + struct ring_buffer_per_cpu *cpu_buffer = m->private; + struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; + unsigned long val; + + if (!meta) + return NULL; + + if (*pos > meta->nr_subbufs) + return NULL; + + val = *pos; + val++; + + return (void *)val; +} + +static void *rbm_next(struct seq_file *m, void *v, loff_t *pos) +{ + (*pos)++; + + return rbm_start(m, pos); +} + +static int rbm_show(struct seq_file *m, void *v) +{ + struct ring_buffer_per_cpu *cpu_buffer = m->private; + struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; + unsigned long val = (unsigned long)v; + + if (val == 1) { + seq_printf(m, "head_buffer: %d\n", + rb_meta_subbuf_idx(meta, (void *)meta->head_buffer)); + seq_printf(m, "commit_buffer: %d\n", + rb_meta_subbuf_idx(meta, (void *)meta->commit_buffer)); + seq_printf(m, "subbuf_size: %d\n", meta->subbuf_size); + seq_printf(m, "nr_subbufs: %d\n", meta->nr_subbufs); + return 0; + } + + val -= 2; + seq_printf(m, "buffer[%ld]: %d\n", val, meta->buffers[val]); + + return 0; +} + +static void rbm_stop(struct seq_file *m, void *p) +{ +} + +static const struct seq_operations rb_meta_seq_ops = { + .start = rbm_start, + .next = rbm_next, + .show = rbm_show, + .stop = rbm_stop, +}; + +int ring_buffer_meta_seq_init(struct file *file, struct trace_buffer *buffer, int cpu) +{ + struct seq_file *m; + int ret; + + ret = seq_open(file, &rb_meta_seq_ops); + if (ret) + return ret; + + m = file->private_data; + m->private = buffer->buffers[cpu]; + + return 0; +} + +/* Map the buffer_pages to the previous head and commit pages */ +static void rb_meta_buffer_update(struct ring_buffer_per_cpu *cpu_buffer, + struct buffer_page *bpage) +{ + struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; + + if (meta->head_buffer == (unsigned long)bpage->page) + cpu_buffer->head_page = bpage; + + if (meta->commit_buffer == (unsigned long)bpage->page) { + cpu_buffer->commit_page = bpage; + cpu_buffer->tail_page = bpage; } } static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, long nr_pages, struct list_head *pages) { + struct trace_buffer *buffer = cpu_buffer->buffer; + struct ring_buffer_cpu_meta *meta = NULL; struct buffer_page *bpage, *tmp; bool user_thread = current->mm != NULL; gfp_t mflags; @@ -1515,6 +2236,10 @@ static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, */ if (user_thread) set_current_oom_origin(); + + if (buffer->range_addr_start) + meta = rb_range_meta(buffer, nr_pages, cpu_buffer->cpu); + for (i = 0; i < nr_pages; i++) { struct page *page; @@ -1525,16 +2250,32 @@ static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, rb_check_bpage(cpu_buffer, bpage); - list_add(&bpage->list, pages); - - page = alloc_pages_node(cpu_to_node(cpu_buffer->cpu), - mflags | __GFP_COMP | __GFP_ZERO, - cpu_buffer->buffer->subbuf_order); - if (!page) - goto free_pages; - bpage->page = page_address(page); + /* + * Append the pages as for mapped buffers we want to keep + * the order + */ + list_add_tail(&bpage->list, pages); + + if (meta) { + /* A range was given. Use that for the buffer page */ + bpage->page = rb_range_buffer(cpu_buffer, i + 1); + if (!bpage->page) + goto free_pages; + /* If this is valid from a previous boot */ + if (meta->head_buffer) + rb_meta_buffer_update(cpu_buffer, bpage); + bpage->range = 1; + bpage->id = i + 1; + } else { + page = alloc_pages_node(cpu_to_node(cpu_buffer->cpu), + mflags | __GFP_COMP | __GFP_ZERO, + cpu_buffer->buffer->subbuf_order); + if (!page) + goto free_pages; + bpage->page = page_address(page); + rb_init_page(bpage->page); + } bpage->order = cpu_buffer->buffer->subbuf_order; - rb_init_page(bpage->page); if (user_thread && fatal_signal_pending(current)) goto free_pages; @@ -1583,7 +2324,8 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, static struct ring_buffer_per_cpu * rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) { - struct ring_buffer_per_cpu *cpu_buffer; + struct ring_buffer_per_cpu *cpu_buffer __free(kfree) = NULL; + struct ring_buffer_cpu_meta *meta; struct buffer_page *bpage; struct page *page; int ret; @@ -1608,18 +2350,34 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), GFP_KERNEL, cpu_to_node(cpu)); if (!bpage) - goto fail_free_buffer; + return NULL; rb_check_bpage(cpu_buffer, bpage); cpu_buffer->reader_page = bpage; - page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_COMP | __GFP_ZERO, - cpu_buffer->buffer->subbuf_order); - if (!page) - goto fail_free_reader; - bpage->page = page_address(page); - rb_init_page(bpage->page); + if (buffer->range_addr_start) { + /* + * Range mapped buffers have the same restrictions as memory + * mapped ones do. + */ + cpu_buffer->mapped = 1; + cpu_buffer->ring_meta = rb_range_meta(buffer, nr_pages, cpu); + bpage->page = rb_range_buffer(cpu_buffer, 0); + if (!bpage->page) + goto fail_free_reader; + if (cpu_buffer->ring_meta->head_buffer) + rb_meta_buffer_update(cpu_buffer, bpage); + bpage->range = 1; + } else { + page = alloc_pages_node(cpu_to_node(cpu), + GFP_KERNEL | __GFP_COMP | __GFP_ZERO, + cpu_buffer->buffer->subbuf_order); + if (!page) + goto fail_free_reader; + bpage->page = page_address(page); + rb_init_page(bpage->page); + } INIT_LIST_HEAD(&cpu_buffer->reader_page->list); INIT_LIST_HEAD(&cpu_buffer->new_pages); @@ -1628,19 +2386,41 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) if (ret < 0) goto fail_free_reader; - cpu_buffer->head_page - = list_entry(cpu_buffer->pages, struct buffer_page, list); - cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; + rb_meta_validate_events(cpu_buffer); + + /* If the boot meta was valid then this has already been updated */ + meta = cpu_buffer->ring_meta; + if (!meta || !meta->head_buffer || + !cpu_buffer->head_page || !cpu_buffer->commit_page || !cpu_buffer->tail_page) { + if (meta && meta->head_buffer && + (cpu_buffer->head_page || cpu_buffer->commit_page || cpu_buffer->tail_page)) { + pr_warn("Ring buffer meta buffers not all mapped\n"); + if (!cpu_buffer->head_page) + pr_warn(" Missing head_page\n"); + if (!cpu_buffer->commit_page) + pr_warn(" Missing commit_page\n"); + if (!cpu_buffer->tail_page) + pr_warn(" Missing tail_page\n"); + } - rb_head_page_activate(cpu_buffer); + cpu_buffer->head_page + = list_entry(cpu_buffer->pages, struct buffer_page, list); + cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; - return cpu_buffer; + rb_head_page_activate(cpu_buffer); + + if (cpu_buffer->ring_meta) + meta->commit_buffer = meta->head_buffer; + } else { + /* The valid meta buffer still needs to activate the head page */ + rb_head_page_activate(cpu_buffer); + } + + return_ptr(cpu_buffer); fail_free_reader: free_buffer_page(cpu_buffer->reader_page); - fail_free_buffer: - kfree(cpu_buffer); return NULL; } @@ -1669,22 +2449,15 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) kfree(cpu_buffer); } -/** - * __ring_buffer_alloc - allocate a new ring_buffer - * @size: the size in bytes per cpu that is needed. - * @flags: attributes to set for the ring buffer. - * @key: ring buffer reader_lock_key. - * - * Currently the only flag that is available is the RB_FL_OVERWRITE - * flag. This flag means that the buffer will overwrite old data - * when the buffer wraps. If this flag is not set, the buffer will - * drop data when the tail hits the head. - */ -struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, - struct lock_class_key *key) +static struct trace_buffer *alloc_buffer(unsigned long size, unsigned flags, + int order, unsigned long start, + unsigned long end, + unsigned long scratch_size, + struct lock_class_key *key) { - struct trace_buffer *buffer; + struct trace_buffer *buffer __free(kfree) = NULL; long nr_pages; + int subbuf_size; int bsize; int cpu; int ret; @@ -1696,16 +2469,15 @@ struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, return NULL; if (!zalloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) - goto fail_free_buffer; + return NULL; - /* Default buffer page size - one system page */ - buffer->subbuf_order = 0; - buffer->subbuf_size = PAGE_SIZE - BUF_PAGE_HDR_SIZE; + buffer->subbuf_order = order; + subbuf_size = (PAGE_SIZE << order); + buffer->subbuf_size = subbuf_size - BUF_PAGE_HDR_SIZE; /* Max payload is buffer page size - header (8bytes) */ buffer->max_data_size = buffer->subbuf_size - (sizeof(u32) * 2); - nr_pages = DIV_ROUND_UP(size, buffer->subbuf_size); buffer->flags = flags; buffer->clock = trace_clock_local; buffer->reader_lock_key = key; @@ -1713,10 +2485,6 @@ struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, init_irq_work(&buffer->irq_work.work, rb_wake_up_waiters); init_waitqueue_head(&buffer->irq_work.waiters); - /* need at least two pages */ - if (nr_pages < 2) - nr_pages = 2; - buffer->cpus = nr_cpu_ids; bsize = sizeof(void *) * nr_cpu_ids; @@ -1725,6 +2493,69 @@ struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, if (!buffer->buffers) goto fail_free_cpumask; + /* If start/end are specified, then that overrides size */ + if (start && end) { + unsigned long buffers_start; + unsigned long ptr; + int n; + + /* Make sure that start is word aligned */ + start = ALIGN(start, sizeof(long)); + + /* scratch_size needs to be aligned too */ + scratch_size = ALIGN(scratch_size, sizeof(long)); + + /* Subtract the buffer meta data and word aligned */ + buffers_start = start + sizeof(struct ring_buffer_cpu_meta); + buffers_start = ALIGN(buffers_start, sizeof(long)); + buffers_start += scratch_size; + + /* Calculate the size for the per CPU data */ + size = end - buffers_start; + size = size / nr_cpu_ids; + + /* + * The number of sub-buffers (nr_pages) is determined by the + * total size allocated minus the meta data size. + * Then that is divided by the number of per CPU buffers + * needed, plus account for the integer array index that + * will be appended to the meta data. + */ + nr_pages = (size - sizeof(struct ring_buffer_cpu_meta)) / + (subbuf_size + sizeof(int)); + /* Need at least two pages plus the reader page */ + if (nr_pages < 3) + goto fail_free_buffers; + + again: + /* Make sure that the size fits aligned */ + for (n = 0, ptr = buffers_start; n < nr_cpu_ids; n++) { + ptr += sizeof(struct ring_buffer_cpu_meta) + + sizeof(int) * nr_pages; + ptr = ALIGN(ptr, subbuf_size); + ptr += subbuf_size * nr_pages; + } + if (ptr > end) { + if (nr_pages <= 3) + goto fail_free_buffers; + nr_pages--; + goto again; + } + + /* nr_pages should not count the reader page */ + nr_pages--; + buffer->range_addr_start = start; + buffer->range_addr_end = end; + + rb_range_meta_init(buffer, nr_pages, scratch_size); + } else { + + /* need at least two pages */ + nr_pages = DIV_ROUND_UP(size, buffer->subbuf_size); + if (nr_pages < 2) + nr_pages = 2; + } + cpu = raw_smp_processor_id(); cpumask_set_cpu(cpu, buffer->cpumask); buffer->buffers[cpu] = rb_allocate_cpu_buffer(buffer, nr_pages, cpu); @@ -1737,7 +2568,7 @@ struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, mutex_init(&buffer->mutex); - return buffer; + return_ptr(buffer); fail_free_buffers: for_each_buffer_cpu(buffer, cpu) { @@ -1749,13 +2580,73 @@ struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, fail_free_cpumask: free_cpumask_var(buffer->cpumask); - fail_free_buffer: - kfree(buffer); return NULL; } + +/** + * __ring_buffer_alloc - allocate a new ring_buffer + * @size: the size in bytes per cpu that is needed. + * @flags: attributes to set for the ring buffer. + * @key: ring buffer reader_lock_key. + * + * Currently the only flag that is available is the RB_FL_OVERWRITE + * flag. This flag means that the buffer will overwrite old data + * when the buffer wraps. If this flag is not set, the buffer will + * drop data when the tail hits the head. + */ +struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, + struct lock_class_key *key) +{ + /* Default buffer page size - one system page */ + return alloc_buffer(size, flags, 0, 0, 0, 0, key); + +} EXPORT_SYMBOL_GPL(__ring_buffer_alloc); /** + * __ring_buffer_alloc_range - allocate a new ring_buffer from existing memory + * @size: the size in bytes per cpu that is needed. + * @flags: attributes to set for the ring buffer. + * @order: sub-buffer order + * @start: start of allocated range + * @range_size: size of allocated range + * @scratch_size: size of scratch area (for preallocated memory buffers) + * @key: ring buffer reader_lock_key. + * + * Currently the only flag that is available is the RB_FL_OVERWRITE + * flag. This flag means that the buffer will overwrite old data + * when the buffer wraps. If this flag is not set, the buffer will + * drop data when the tail hits the head. + */ +struct trace_buffer *__ring_buffer_alloc_range(unsigned long size, unsigned flags, + int order, unsigned long start, + unsigned long range_size, + unsigned long scratch_size, + struct lock_class_key *key) +{ + return alloc_buffer(size, flags, order, start, start + range_size, + scratch_size, key); +} + +void *ring_buffer_meta_scratch(struct trace_buffer *buffer, unsigned int *size) +{ + struct ring_buffer_meta *meta; + void *ptr; + + if (!buffer || !buffer->meta) + return NULL; + + meta = buffer->meta; + + ptr = (void *)ALIGN((unsigned long)meta + sizeof(*meta), sizeof(long)); + + if (size) + *size = (void *)meta + meta->buffers_offset - ptr; + + return ptr; +} + +/** * ring_buffer_free - free a ring buffer. * @buffer: the buffer to free. */ @@ -1862,6 +2753,7 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages) /* make sure pages points to a valid page in the ring buffer */ cpu_buffer->pages = next_page; + cpu_buffer->cnt++; /* update head page */ if (head_bit) @@ -1968,6 +2860,7 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer) * pointer to point to end of list */ head_page->prev = last_page; + cpu_buffer->cnt++; success = true; break; } @@ -2050,6 +2943,12 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, if (nr_pages < 2) nr_pages = 2; + /* + * Keep CPUs from coming online while resizing to synchronize + * with new per CPU buffers being created. + */ + guard(cpus_read_lock)(); + /* prevent another thread from changing buffer sizes */ mutex_lock(&buffer->mutex); atomic_inc(&buffer->resizing); @@ -2094,7 +2993,6 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, cond_resched(); } - cpus_read_lock(); /* * Fire off all the required work handlers * We can't schedule on offline CPUs, but it's not necessary @@ -2134,7 +3032,6 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, cpu_buffer->nr_pages_to_update = 0; } - cpus_read_unlock(); } else { cpu_buffer = buffer->buffers[cpu_id]; @@ -2162,8 +3059,6 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, goto out_err; } - cpus_read_lock(); - /* Can't run something on an offline CPU. */ if (!cpu_online(cpu_id)) rb_update_pages(cpu_buffer); @@ -2182,7 +3077,6 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, } cpu_buffer->nr_pages_to_update = 0; - cpus_read_unlock(); } out: @@ -2203,12 +3097,8 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, */ synchronize_rcu(); for_each_buffer_cpu(buffer, cpu) { - unsigned long flags; - cpu_buffer = buffer->buffers[cpu]; - raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rb_check_pages(cpu_buffer); - raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } atomic_dec(&buffer->record_disabled); } @@ -2364,6 +3254,52 @@ static void rb_inc_iter(struct ring_buffer_iter *iter) iter->next_event = 0; } +/* Return the index into the sub-buffers for a given sub-buffer */ +static int rb_meta_subbuf_idx(struct ring_buffer_cpu_meta *meta, void *subbuf) +{ + void *subbuf_array; + + subbuf_array = (void *)meta + sizeof(int) * meta->nr_subbufs; + subbuf_array = (void *)ALIGN((unsigned long)subbuf_array, meta->subbuf_size); + return (subbuf - subbuf_array) / meta->subbuf_size; +} + +static void rb_update_meta_head(struct ring_buffer_per_cpu *cpu_buffer, + struct buffer_page *next_page) +{ + struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; + unsigned long old_head = (unsigned long)next_page->page; + unsigned long new_head; + + rb_inc_page(&next_page); + new_head = (unsigned long)next_page->page; + + /* + * Only move it forward once, if something else came in and + * moved it forward, then we don't want to touch it. + */ + (void)cmpxchg(&meta->head_buffer, old_head, new_head); +} + +static void rb_update_meta_reader(struct ring_buffer_per_cpu *cpu_buffer, + struct buffer_page *reader) +{ + struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; + void *old_reader = cpu_buffer->reader_page->page; + void *new_reader = reader->page; + int id; + + id = reader->id; + cpu_buffer->reader_page->id = id; + reader->id = 0; + + meta->buffers[0] = rb_meta_subbuf_idx(meta, new_reader); + meta->buffers[id] = rb_meta_subbuf_idx(meta, old_reader); + + /* The head pointer is the one after the reader */ + rb_update_meta_head(cpu_buffer, reader); +} + /* * rb_handle_head_page - writer hit the head page * @@ -2413,6 +3349,8 @@ rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, local_sub(rb_page_commit(next_page), &cpu_buffer->entries_bytes); local_inc(&cpu_buffer->pages_lost); + if (cpu_buffer->ring_meta) + rb_update_meta_head(cpu_buffer, next_page); /* * The entries will be zeroed out when we move the * tail page. @@ -2974,6 +3912,10 @@ rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) local_set(&cpu_buffer->commit_page->page->commit, rb_page_write(cpu_buffer->commit_page)); rb_inc_page(&cpu_buffer->commit_page); + if (cpu_buffer->ring_meta) { + struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; + meta->commit_buffer = (unsigned long)cpu_buffer->commit_page->page; + } /* add barrier to keep gcc from optimizing too much */ barrier(); } @@ -3274,7 +4216,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); static const char *show_irq_str(int bits) { - const char *type[] = { + static const char * type[] = { ".", // 0 "s", // 1 "h", // 2 @@ -3288,7 +4230,7 @@ static const char *show_irq_str(int bits) return type[bits]; } -/* Assume this is an trace event */ +/* Assume this is a trace event */ static const char *show_flags(struct ring_buffer_event *event) { struct trace_entry *entry; @@ -3420,11 +4362,10 @@ static void check_buffer(struct ring_buffer_per_cpu *cpu_buffer, struct rb_event_info *info, unsigned long tail) { - struct ring_buffer_event *event; struct buffer_data_page *bpage; u64 ts, delta; bool full = false; - int e; + int ret; bpage = info->tail_page->page; @@ -3450,39 +4391,12 @@ static void check_buffer(struct ring_buffer_per_cpu *cpu_buffer, if (atomic_inc_return(this_cpu_ptr(&checking)) != 1) goto out; - ts = bpage->time_stamp; - - for (e = 0; e < tail; e += rb_event_length(event)) { - - event = (struct ring_buffer_event *)(bpage->data + e); - - switch (event->type_len) { - - case RINGBUF_TYPE_TIME_EXTEND: - delta = rb_event_time_stamp(event); - ts += delta; - break; - - case RINGBUF_TYPE_TIME_STAMP: - delta = rb_event_time_stamp(event); - delta = rb_fix_abs_ts(delta, ts); - if (delta < ts) { - buffer_warn_return("[CPU: %d]ABSOLUTE TIME WENT BACKWARDS: last ts: %lld absolute ts: %lld\n", - cpu_buffer->cpu, ts, delta); - } - ts = delta; - break; - - case RINGBUF_TYPE_PADDING: - if (event->time_delta == 1) - break; - fallthrough; - case RINGBUF_TYPE_DATA: - ts += event->time_delta; - break; - - default: - RB_WARN_ON(cpu_buffer, 1); + ret = rb_read_data_buffer(bpage, tail, cpu_buffer->cpu, &ts, &delta); + if (ret < 0) { + if (delta < ts) { + buffer_warn_return("[CPU: %d]ABSOLUTE TIME WENT BACKWARDS: last ts: %lld absolute ts: %lld\n", + cpu_buffer->cpu, ts, delta); + goto out; } } if ((full && ts > info->ts) || @@ -3657,8 +4571,13 @@ rb_reserve_next_event(struct trace_buffer *buffer, int nr_loops = 0; int add_ts_default; - /* ring buffer does cmpxchg, make sure it is safe in NMI context */ - if (!IS_ENABLED(CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG) && + /* + * ring buffer does cmpxchg as well as atomic64 operations + * (which some archs use locking for atomic64), make sure this + * is safe in NMI context + */ + if ((!IS_ENABLED(CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG) || + IS_ENABLED(CONFIG_GENERIC_ATOMIC64)) && (unlikely(in_nmi()))) { return NULL; } @@ -3860,10 +4779,7 @@ void ring_buffer_discard_commit(struct trace_buffer *buffer, RB_WARN_ON(buffer, !local_read(&cpu_buffer->committing)); rb_decrement_entry(cpu_buffer, event); - if (rb_try_to_discard(cpu_buffer, event)) - goto out; - - out: + rb_try_to_discard(cpu_buffer, event); rb_end_commit(cpu_buffer); trace_recursive_unlock(cpu_buffer); @@ -3896,26 +4812,26 @@ int ring_buffer_write(struct trace_buffer *buffer, int ret = -EBUSY; int cpu; - preempt_disable_notrace(); + guard(preempt_notrace)(); if (atomic_read(&buffer->record_disabled)) - goto out; + return -EBUSY; cpu = raw_smp_processor_id(); if (!cpumask_test_cpu(cpu, buffer->cpumask)) - goto out; + return -EBUSY; cpu_buffer = buffer->buffers[cpu]; if (atomic_read(&cpu_buffer->record_disabled)) - goto out; + return -EBUSY; if (length > buffer->max_data_size) - goto out; + return -EBUSY; if (unlikely(trace_recursive_lock(cpu_buffer))) - goto out; + return -EBUSY; event = rb_reserve_next_event(buffer, cpu_buffer, length); if (!event) @@ -3933,48 +4849,26 @@ int ring_buffer_write(struct trace_buffer *buffer, out_unlock: trace_recursive_unlock(cpu_buffer); - - out: - preempt_enable_notrace(); - return ret; } EXPORT_SYMBOL_GPL(ring_buffer_write); -static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) +/* + * The total entries in the ring buffer is the running counter + * of entries entered into the ring buffer, minus the sum of + * the entries read from the ring buffer and the number of + * entries that were overwritten. + */ +static inline unsigned long +rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer) { - struct buffer_page *reader = cpu_buffer->reader_page; - struct buffer_page *head = rb_set_head_page(cpu_buffer); - struct buffer_page *commit = cpu_buffer->commit_page; - - /* In case of error, head will be NULL */ - if (unlikely(!head)) - return true; - - /* Reader should exhaust content in reader page */ - if (reader->read != rb_page_size(reader)) - return false; - - /* - * If writers are committing on the reader page, knowing all - * committed content has been read, the ring buffer is empty. - */ - if (commit == reader) - return true; - - /* - * If writers are committing on a page other than reader page - * and head page, there should always be content to read. - */ - if (commit != head) - return false; + return local_read(&cpu_buffer->entries) - + (local_read(&cpu_buffer->overrun) + cpu_buffer->read); +} - /* - * Writers are committing on the head page, we just need - * to care about there're committed data, and the reader will - * swap reader page with head page when it is to read data. - */ - return rb_page_commit(commit) == 0; +static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) +{ + return !rb_num_of_entries(cpu_buffer); } /** @@ -4079,6 +4973,24 @@ bool ring_buffer_record_is_set_on(struct trace_buffer *buffer) } /** + * ring_buffer_record_is_on_cpu - return true if the ring buffer can write + * @buffer: The ring buffer to see if write is enabled + * @cpu: The CPU to test if the ring buffer can write too + * + * Returns true if the ring buffer is in a state that it accepts writes + * for a particular CPU. + */ +bool ring_buffer_record_is_on_cpu(struct trace_buffer *buffer, int cpu) +{ + struct ring_buffer_per_cpu *cpu_buffer; + + cpu_buffer = buffer->buffers[cpu]; + + return ring_buffer_record_is_set_on(buffer) && + !atomic_read(&cpu_buffer->record_disabled); +} + +/** * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer * @buffer: The ring buffer to stop writes to. * @cpu: The CPU buffer to stop @@ -4120,19 +5032,6 @@ void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu) } EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); -/* - * The total entries in the ring buffer is the running counter - * of entries entered into the ring buffer, minus the sum of - * the entries read from the ring buffer and the number of - * entries that were overwritten. - */ -static inline unsigned long -rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer) -{ - return local_read(&cpu_buffer->entries) - - (local_read(&cpu_buffer->overrun) + cpu_buffer->read); -} - /** * ring_buffer_oldest_event_ts - get the oldest event timestamp from the buffer * @buffer: The ring buffer @@ -4537,7 +5436,6 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) */ local_set(&cpu_buffer->reader_page->write, 0); local_set(&cpu_buffer->reader_page->entries, 0); - local_set(&cpu_buffer->reader_page->page->commit, 0); cpu_buffer->reader_page->real_end = 0; spin: @@ -4580,7 +5478,7 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) * moving it. The page before the header page has the * flag bit '1' set if it is pointing to the page we want. * but if the writer is in the process of moving it - * than it will be '2' or already moved '0'. + * then it will be '2' or already moved '0'. */ ret = rb_head_page_replace(reader, cpu_buffer->reader_page); @@ -4591,6 +5489,9 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) if (!ret) goto spin; + if (cpu_buffer->ring_meta) + rb_update_meta_reader(cpu_buffer, reader); + /* * Yay! We succeeded in replacing the page. * @@ -4599,6 +5500,7 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list; rb_inc_page(&cpu_buffer->head_page); + cpu_buffer->cnt++; local_inc(&cpu_buffer->pages_read); /* Finally update the reader page to the new head */ @@ -5037,24 +5939,20 @@ ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts, EXPORT_SYMBOL_GPL(ring_buffer_consume); /** - * ring_buffer_read_prepare - Prepare for a non consuming read of the buffer + * ring_buffer_read_start - start a non consuming read of the buffer * @buffer: The ring buffer to read from * @cpu: The cpu buffer to iterate over * @flags: gfp flags to use for memory allocation * - * This performs the initial preparations necessary to iterate - * through the buffer. Memory is allocated, buffer resizing - * is disabled, and the iterator pointer is returned to the caller. - * - * After a sequence of ring_buffer_read_prepare calls, the user is - * expected to make at least one call to ring_buffer_read_prepare_sync. - * Afterwards, ring_buffer_read_start is invoked to get things going - * for real. + * This creates an iterator to allow non-consuming iteration through + * the buffer. If the buffer is disabled for writing, it will produce + * the same information each time, but if the buffer is still writing + * then the first hit of a write will cause the iteration to stop. * - * This overall must be paired with ring_buffer_read_finish. + * Must be paired with ring_buffer_read_finish. */ struct ring_buffer_iter * -ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags) +ring_buffer_read_start(struct trace_buffer *buffer, int cpu, gfp_t flags) { struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_iter *iter; @@ -5080,51 +5978,12 @@ ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags) atomic_inc(&cpu_buffer->resize_disabled); - return iter; -} -EXPORT_SYMBOL_GPL(ring_buffer_read_prepare); - -/** - * ring_buffer_read_prepare_sync - Synchronize a set of prepare calls - * - * All previously invoked ring_buffer_read_prepare calls to prepare - * iterators will be synchronized. Afterwards, read_buffer_read_start - * calls on those iterators are allowed. - */ -void -ring_buffer_read_prepare_sync(void) -{ - synchronize_rcu(); -} -EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync); - -/** - * ring_buffer_read_start - start a non consuming read of the buffer - * @iter: The iterator returned by ring_buffer_read_prepare - * - * This finalizes the startup of an iteration through the buffer. - * The iterator comes from a call to ring_buffer_read_prepare and - * an intervening ring_buffer_read_prepare_sync must have been - * performed. - * - * Must be paired with ring_buffer_read_finish. - */ -void -ring_buffer_read_start(struct ring_buffer_iter *iter) -{ - struct ring_buffer_per_cpu *cpu_buffer; - unsigned long flags; - - if (!iter) - return; - - cpu_buffer = iter->cpu_buffer; - - raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + guard(raw_spinlock_irqsave)(&cpu_buffer->reader_lock); arch_spin_lock(&cpu_buffer->lock); rb_iter_reset(iter); arch_spin_unlock(&cpu_buffer->lock); - raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + + return iter; } EXPORT_SYMBOL_GPL(ring_buffer_read_start); @@ -5138,12 +5997,9 @@ void ring_buffer_read_finish(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; - unsigned long flags; /* Use this opportunity to check the integrity of the ring buffer. */ - raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rb_check_pages(cpu_buffer); - raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); atomic_dec(&cpu_buffer->resize_disabled); kfree(iter->event); @@ -5208,12 +6064,50 @@ static void rb_clear_buffer_page(struct buffer_page *page) page->read = 0; } +/* + * When the buffer is memory mapped to user space, each sub buffer + * has a unique id that is used by the meta data to tell the user + * where the current reader page is. + * + * For a normal allocated ring buffer, the id is saved in the buffer page + * id field, and updated via this function. + * + * But for a fixed memory mapped buffer, the id is already assigned for + * fixed memory ording in the memory layout and can not be used. Instead + * the index of where the page lies in the memory layout is used. + * + * For the normal pages, set the buffer page id with the passed in @id + * value and return that. + * + * For fixed memory mapped pages, get the page index in the memory layout + * and return that as the id. + */ +static int rb_page_id(struct ring_buffer_per_cpu *cpu_buffer, + struct buffer_page *bpage, int id) +{ + /* + * For boot buffers, the id is the index, + * otherwise, set the buffer page with this id + */ + if (cpu_buffer->ring_meta) + id = rb_meta_subbuf_idx(cpu_buffer->ring_meta, bpage->page); + else + bpage->id = id; + + return id; +} + static void rb_update_meta_page(struct ring_buffer_per_cpu *cpu_buffer) { struct trace_buffer_meta *meta = cpu_buffer->meta_page; + if (!meta) + return; + meta->reader.read = cpu_buffer->reader_page->read; - meta->reader.id = cpu_buffer->reader_page->id; + meta->reader.id = rb_page_id(cpu_buffer, cpu_buffer->reader_page, + cpu_buffer->reader_page->id); + meta->reader.lost_events = cpu_buffer->lost_events; meta->entries = local_read(&cpu_buffer->entries); @@ -5221,7 +6115,7 @@ static void rb_update_meta_page(struct ring_buffer_per_cpu *cpu_buffer) meta->read = cpu_buffer->read; /* Some archs do not have data cache coherency between kernel and user-space */ - flush_dcache_folio(virt_to_folio(cpu_buffer->meta_page)); + flush_kernel_vmap_range(cpu_buffer->meta_page, PAGE_SIZE); } static void @@ -5268,31 +6162,31 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) cpu_buffer->lost_events = 0; cpu_buffer->last_overrun = 0; - if (cpu_buffer->mapped) - rb_update_meta_page(cpu_buffer); - rb_head_page_activate(cpu_buffer); cpu_buffer->pages_removed = 0; + + if (cpu_buffer->mapped) { + rb_update_meta_page(cpu_buffer); + if (cpu_buffer->ring_meta) { + struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; + meta->commit_buffer = meta->head_buffer; + } + } } /* Must have disabled the cpu buffer then done a synchronize_rcu */ static void reset_disabled_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) { - unsigned long flags; - - raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + guard(raw_spinlock_irqsave)(&cpu_buffer->reader_lock); if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing))) - goto out; + return; arch_spin_lock(&cpu_buffer->lock); rb_reset_cpu(cpu_buffer); arch_spin_unlock(&cpu_buffer->lock); - - out: - raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } /** @@ -5480,37 +6374,33 @@ int ring_buffer_swap_cpu(struct trace_buffer *buffer_a, if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || !cpumask_test_cpu(cpu, buffer_b->cpumask)) - goto out; + return -EINVAL; cpu_buffer_a = buffer_a->buffers[cpu]; cpu_buffer_b = buffer_b->buffers[cpu]; /* It's up to the callers to not try to swap mapped buffers */ - if (WARN_ON_ONCE(cpu_buffer_a->mapped || cpu_buffer_b->mapped)) { - ret = -EBUSY; - goto out; - } + if (WARN_ON_ONCE(cpu_buffer_a->mapped || cpu_buffer_b->mapped)) + return -EBUSY; /* At least make sure the two buffers are somewhat the same */ if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages) - goto out; + return -EINVAL; if (buffer_a->subbuf_order != buffer_b->subbuf_order) - goto out; - - ret = -EAGAIN; + return -EINVAL; if (atomic_read(&buffer_a->record_disabled)) - goto out; + return -EAGAIN; if (atomic_read(&buffer_b->record_disabled)) - goto out; + return -EAGAIN; if (atomic_read(&cpu_buffer_a->record_disabled)) - goto out; + return -EAGAIN; if (atomic_read(&cpu_buffer_b->record_disabled)) - goto out; + return -EAGAIN; /* * We can't do a synchronize_rcu here because this @@ -5547,7 +6437,6 @@ int ring_buffer_swap_cpu(struct trace_buffer *buffer_a, out_dec: atomic_dec(&cpu_buffer_a->record_disabled); atomic_dec(&cpu_buffer_b->record_disabled); -out: return ret; } EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); @@ -5706,38 +6595,37 @@ int ring_buffer_read_page(struct trace_buffer *buffer, struct buffer_data_page *bpage; struct buffer_page *reader; unsigned long missed_events; - unsigned long flags; unsigned int commit; unsigned int read; u64 save_timestamp; - int ret = -1; if (!cpumask_test_cpu(cpu, buffer->cpumask)) - goto out; + return -1; /* * If len is not big enough to hold the page header, then * we can not copy anything. */ if (len <= BUF_PAGE_HDR_SIZE) - goto out; + return -1; len -= BUF_PAGE_HDR_SIZE; if (!data_page || !data_page->data) - goto out; + return -1; + if (data_page->order != buffer->subbuf_order) - goto out; + return -1; bpage = data_page->data; if (!bpage) - goto out; + return -1; - raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + guard(raw_spinlock_irqsave)(&cpu_buffer->reader_lock); reader = rb_get_reader_page(cpu_buffer); if (!reader) - goto out_unlock; + return -1; event = rb_reader_event(cpu_buffer); @@ -5771,7 +6659,7 @@ int ring_buffer_read_page(struct trace_buffer *buffer, if (full && (!read || (len < (commit - read)) || cpu_buffer->reader_page == cpu_buffer->commit_page)) - goto out_unlock; + return -1; if (len > (commit - read)) len = (commit - read); @@ -5780,7 +6668,7 @@ int ring_buffer_read_page(struct trace_buffer *buffer, size = rb_event_ts_length(event); if (len < size) - goto out_unlock; + return -1; /* save the current timestamp, since the user will need it */ save_timestamp = cpu_buffer->read_stamp; @@ -5838,7 +6726,6 @@ int ring_buffer_read_page(struct trace_buffer *buffer, if (reader->real_end) local_set(&bpage->commit, reader->real_end); } - ret = read; cpu_buffer->lost_events = 0; @@ -5865,11 +6752,7 @@ int ring_buffer_read_page(struct trace_buffer *buffer, if (commit < buffer->subbuf_size) memset(&bpage->data[commit], 0, buffer->subbuf_size - commit); - out_unlock: - raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); - - out: - return ret; + return read; } EXPORT_SYMBOL_GPL(ring_buffer_read_page); @@ -5962,7 +6845,7 @@ int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order) old_size = buffer->subbuf_size; /* prevent another thread from changing buffer sizes */ - mutex_lock(&buffer->mutex); + guard(mutex)(&buffer->mutex); atomic_inc(&buffer->record_disabled); /* Make sure all commits have finished */ @@ -6008,39 +6891,39 @@ int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order) } for_each_buffer_cpu(buffer, cpu) { + struct buffer_data_page *old_free_data_page; + struct list_head old_pages; + unsigned long flags; if (!cpumask_test_cpu(cpu, buffer->cpumask)) continue; cpu_buffer = buffer->buffers[cpu]; + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + /* Clear the head bit to make the link list normal to read */ rb_head_page_deactivate(cpu_buffer); - /* Now walk the list and free all the old sub buffers */ - list_for_each_entry_safe(bpage, tmp, cpu_buffer->pages, list) { - list_del_init(&bpage->list); - free_buffer_page(bpage); - } - /* The above loop stopped an the last page needing to be freed */ - bpage = list_entry(cpu_buffer->pages, struct buffer_page, list); - free_buffer_page(bpage); - - /* Free the current reader page */ - free_buffer_page(cpu_buffer->reader_page); + /* + * Collect buffers from the cpu_buffer pages list and the + * reader_page on old_pages, so they can be freed later when not + * under a spinlock. The pages list is a linked list with no + * head, adding old_pages turns it into a regular list with + * old_pages being the head. + */ + list_add(&old_pages, cpu_buffer->pages); + list_add(&cpu_buffer->reader_page->list, &old_pages); /* One page was allocated for the reader page */ cpu_buffer->reader_page = list_entry(cpu_buffer->new_pages.next, struct buffer_page, list); list_del_init(&cpu_buffer->reader_page->list); - /* The cpu_buffer pages are a link list with no head */ + /* Install the new pages, remove the head from the list */ cpu_buffer->pages = cpu_buffer->new_pages.next; - cpu_buffer->new_pages.next->prev = cpu_buffer->new_pages.prev; - cpu_buffer->new_pages.prev->next = cpu_buffer->new_pages.next; - - /* Clear the new_pages list */ - INIT_LIST_HEAD(&cpu_buffer->new_pages); + list_del_init(&cpu_buffer->new_pages); + cpu_buffer->cnt++; cpu_buffer->head_page = list_entry(cpu_buffer->pages, struct buffer_page, list); @@ -6049,16 +6932,24 @@ int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order) cpu_buffer->nr_pages = cpu_buffer->nr_pages_to_update; cpu_buffer->nr_pages_to_update = 0; - free_pages((unsigned long)cpu_buffer->free_page, old_order); + old_free_data_page = cpu_buffer->free_page; cpu_buffer->free_page = NULL; rb_head_page_activate(cpu_buffer); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + + /* Free old sub buffers */ + list_for_each_entry_safe(bpage, tmp, &old_pages, list) { + list_del_init(&bpage->list); + free_buffer_page(bpage); + } + free_pages((unsigned long)old_free_data_page, old_order); + rb_check_pages(cpu_buffer); } atomic_dec(&buffer->record_disabled); - mutex_unlock(&buffer->mutex); return 0; @@ -6067,7 +6958,6 @@ error: buffer->subbuf_size = old_size; atomic_dec(&buffer->record_disabled); - mutex_unlock(&buffer->mutex); for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; @@ -6115,30 +7005,36 @@ static void rb_setup_ids_meta_page(struct ring_buffer_per_cpu *cpu_buffer, struct trace_buffer_meta *meta = cpu_buffer->meta_page; unsigned int nr_subbufs = cpu_buffer->nr_pages + 1; struct buffer_page *first_subbuf, *subbuf; + int cnt = 0; int id = 0; - subbuf_ids[id] = (unsigned long)cpu_buffer->reader_page->page; - cpu_buffer->reader_page->id = id++; + id = rb_page_id(cpu_buffer, cpu_buffer->reader_page, id); + subbuf_ids[id++] = (unsigned long)cpu_buffer->reader_page->page; + cnt++; first_subbuf = subbuf = rb_set_head_page(cpu_buffer); do { + id = rb_page_id(cpu_buffer, subbuf, id); + if (WARN_ON(id >= nr_subbufs)) break; subbuf_ids[id] = (unsigned long)subbuf->page; - subbuf->id = id; rb_inc_page(&subbuf); id++; + cnt++; } while (subbuf != first_subbuf); + WARN_ON(cnt != nr_subbufs); + /* install subbuf ID to kern VA translation */ cpu_buffer->subbuf_ids = subbuf_ids; - meta->meta_page_size = PAGE_SIZE; meta->meta_struct_len = sizeof(*meta); meta->nr_subbufs = nr_subbufs; meta->subbuf_size = cpu_buffer->buffer->subbuf_size + BUF_PAGE_HDR_SIZE; + meta->meta_page_size = meta->subbuf_size; rb_update_meta_page(cpu_buffer); } @@ -6155,7 +7051,7 @@ rb_get_mapped_buffer(struct trace_buffer *buffer, int cpu) mutex_lock(&cpu_buffer->mapping_lock); - if (!cpu_buffer->mapped) { + if (!cpu_buffer->user_mapped) { mutex_unlock(&cpu_buffer->mapping_lock); return ERR_PTR(-ENODEV); } @@ -6179,19 +7075,26 @@ static int __rb_inc_dec_mapped(struct ring_buffer_per_cpu *cpu_buffer, lockdep_assert_held(&cpu_buffer->mapping_lock); + /* mapped is always greater or equal to user_mapped */ + if (WARN_ON(cpu_buffer->mapped < cpu_buffer->user_mapped)) + return -EINVAL; + if (inc && cpu_buffer->mapped == UINT_MAX) return -EBUSY; - if (WARN_ON(!inc && cpu_buffer->mapped == 0)) + if (WARN_ON(!inc && cpu_buffer->user_mapped == 0)) return -EINVAL; mutex_lock(&cpu_buffer->buffer->mutex); raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); - if (inc) + if (inc) { + cpu_buffer->user_mapped++; cpu_buffer->mapped++; - else + } else { + cpu_buffer->user_mapped--; cpu_buffer->mapped--; + } raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); mutex_unlock(&cpu_buffer->buffer->mutex); @@ -6214,9 +7117,9 @@ static int __rb_inc_dec_mapped(struct ring_buffer_per_cpu *cpu_buffer, static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, struct vm_area_struct *vma) { - unsigned long nr_subbufs, nr_pages, vma_pages, pgoff = vma->vm_pgoff; + unsigned long nr_subbufs, nr_pages, nr_vma_pages, pgoff = vma->vm_pgoff; unsigned int subbuf_pages, subbuf_order; - struct page **pages; + struct page **pages __free(kfree) = NULL; int p = 0, s = 0; int err; @@ -6225,6 +7128,12 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, !(vma->vm_flags & VM_MAYSHARE)) return -EPERM; + subbuf_order = cpu_buffer->buffer->subbuf_order; + subbuf_pages = 1 << subbuf_order; + + if (subbuf_order && pgoff % subbuf_pages) + return -EINVAL; + /* * Make sure the mapping cannot become writable later. Also tell the VM * to not touch these pages (VM_DONTCOPY | VM_DONTEXPAND). @@ -6234,49 +7143,54 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, lockdep_assert_held(&cpu_buffer->mapping_lock); - subbuf_order = cpu_buffer->buffer->subbuf_order; - subbuf_pages = 1 << subbuf_order; - nr_subbufs = cpu_buffer->nr_pages + 1; /* + reader-subbuf */ - nr_pages = ((nr_subbufs) << subbuf_order) - pgoff + 1; /* + meta-page */ + nr_pages = ((nr_subbufs + 1) << subbuf_order); /* + meta-page */ + if (nr_pages <= pgoff) + return -EINVAL; + + nr_pages -= pgoff; - vma_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; - if (!vma_pages || vma_pages > nr_pages) + nr_vma_pages = vma_pages(vma); + if (!nr_vma_pages || nr_vma_pages > nr_pages) return -EINVAL; - nr_pages = vma_pages; + nr_pages = nr_vma_pages; pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL); if (!pages) return -ENOMEM; if (!pgoff) { + unsigned long meta_page_padding; + pages[p++] = virt_to_page(cpu_buffer->meta_page); /* - * TODO: Align sub-buffers on their size, once - * vm_insert_pages() supports the zero-page. + * Pad with the zero-page to align the meta-page with the + * sub-buffers. */ - } else { - /* Skip the meta-page */ - pgoff--; + meta_page_padding = subbuf_pages - 1; + while (meta_page_padding-- && p < nr_pages) { + unsigned long __maybe_unused zero_addr = + vma->vm_start + (PAGE_SIZE * p); - if (pgoff % subbuf_pages) { - err = -EINVAL; - goto out; + pages[p++] = ZERO_PAGE(zero_addr); } + } else { + /* Skip the meta-page */ + pgoff -= subbuf_pages; s += pgoff / subbuf_pages; } while (p < nr_pages) { - struct page *page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]); + struct page *page; int off = 0; - if (WARN_ON_ONCE(s >= nr_subbufs)) { - err = -EINVAL; - goto out; - } + if (WARN_ON_ONCE(s >= nr_subbufs)) + return -EINVAL; + + page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]); for (; off < (1 << (subbuf_order)); off++, page++) { if (p >= nr_pages) @@ -6289,9 +7203,6 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, err = vm_insert_pages(vma, vma->vm_start, pages, &nr_pages); -out: - kfree(pages); - return err; } #else @@ -6307,36 +7218,34 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu, { struct ring_buffer_per_cpu *cpu_buffer; unsigned long flags, *subbuf_ids; - int err = 0; + int err; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return -EINVAL; cpu_buffer = buffer->buffers[cpu]; - mutex_lock(&cpu_buffer->mapping_lock); + guard(mutex)(&cpu_buffer->mapping_lock); - if (cpu_buffer->mapped) { + if (cpu_buffer->user_mapped) { err = __rb_map_vma(cpu_buffer, vma); if (!err) err = __rb_inc_dec_mapped(cpu_buffer, true); - mutex_unlock(&cpu_buffer->mapping_lock); return err; } /* prevent another thread from changing buffer/sub-buffer sizes */ - mutex_lock(&buffer->mutex); + guard(mutex)(&buffer->mutex); err = rb_alloc_meta_page(cpu_buffer); if (err) - goto unlock; + return err; /* subbuf_ids include the reader while nr_pages does not */ subbuf_ids = kcalloc(cpu_buffer->nr_pages + 1, sizeof(*subbuf_ids), GFP_KERNEL); if (!subbuf_ids) { rb_free_meta_page(cpu_buffer); - err = -ENOMEM; - goto unlock; + return -ENOMEM; } atomic_inc(&cpu_buffer->resize_disabled); @@ -6347,51 +7256,52 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu, */ raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rb_setup_ids_meta_page(cpu_buffer, subbuf_ids); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); err = __rb_map_vma(cpu_buffer, vma); if (!err) { raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); - cpu_buffer->mapped = 1; + /* This is the first time it is mapped by user */ + cpu_buffer->mapped++; + cpu_buffer->user_mapped = 1; raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } else { kfree(cpu_buffer->subbuf_ids); cpu_buffer->subbuf_ids = NULL; rb_free_meta_page(cpu_buffer); + atomic_dec(&cpu_buffer->resize_disabled); } -unlock: - mutex_unlock(&buffer->mutex); - mutex_unlock(&cpu_buffer->mapping_lock); - - return err; + return 0; } int ring_buffer_unmap(struct trace_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long flags; - int err = 0; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return -EINVAL; cpu_buffer = buffer->buffers[cpu]; - mutex_lock(&cpu_buffer->mapping_lock); + guard(mutex)(&cpu_buffer->mapping_lock); - if (!cpu_buffer->mapped) { - err = -ENODEV; - goto out; - } else if (cpu_buffer->mapped > 1) { + if (!cpu_buffer->user_mapped) { + return -ENODEV; + } else if (cpu_buffer->user_mapped > 1) { __rb_inc_dec_mapped(cpu_buffer, false); - goto out; + return 0; } - mutex_lock(&buffer->mutex); + guard(mutex)(&buffer->mutex); raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); - cpu_buffer->mapped = 0; + /* This is the last user space mapping */ + if (!WARN_ON_ONCE(cpu_buffer->mapped < cpu_buffer->user_mapped)) + cpu_buffer->mapped--; + cpu_buffer->user_mapped = 0; raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); @@ -6400,12 +7310,7 @@ int ring_buffer_unmap(struct trace_buffer *buffer, int cpu) rb_free_meta_page(cpu_buffer); atomic_dec(&cpu_buffer->resize_disabled); - mutex_unlock(&buffer->mutex); - -out: - mutex_unlock(&cpu_buffer->mapping_lock); - - return err; + return 0; } int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu) @@ -6446,8 +7351,8 @@ consume: /* Check if any events were dropped */ missed_events = cpu_buffer->lost_events; - if (cpu_buffer->reader_page != cpu_buffer->commit_page) { - if (missed_events) { + if (missed_events) { + if (cpu_buffer->reader_page != cpu_buffer->commit_page) { struct buffer_data_page *bpage = reader->page; unsigned int commit; /* @@ -6468,13 +7373,23 @@ consume: local_add(RB_MISSED_STORED, &bpage->commit); } local_add(RB_MISSED_EVENTS, &bpage->commit); + } else if (!WARN_ONCE(cpu_buffer->reader_page == cpu_buffer->tail_page, + "Reader on commit with %ld missed events", + missed_events)) { + /* + * There shouldn't be any missed events if the tail_page + * is on the reader page. But if the tail page is not on the + * reader page and the commit_page is, that would mean that + * there's a commit_overrun (an interrupt preempted an + * addition of an event and then filled the buffer + * with new events). In this case it's not an + * error, but it should still be reported. + * + * TODO: Add missed events to the page for user space to know. + */ + pr_info("Ring buffer [%d] commit overrun lost %ld events at timestamp:%lld\n", + cpu, missed_events, cpu_buffer->reader_page->page->time_stamp); } - } else { - /* - * There really shouldn't be any missed events if the commit - * is on the reader page. - */ - WARN_ON_ONCE(missed_events); } cpu_buffer->lost_events = 0; @@ -6483,7 +7398,8 @@ consume: out: /* Some archs do not have data cache coherency between kernel and user-space */ - flush_dcache_folio(virt_to_folio(cpu_buffer->reader_page->page)); + flush_kernel_vmap_range(cpu_buffer->reader_page->page, + buffer->subbuf_size + BUF_PAGE_HDR_SIZE); rb_update_meta_page(cpu_buffer); @@ -6616,9 +7532,9 @@ static __init int rb_write_something(struct rb_test_data *data, bool nested) /* Ignore dropped events before test starts. */ if (started) { if (nested) - data->bytes_dropped += len; - else data->bytes_dropped_nested += len; + else + data->bytes_dropped += len; } return len; } @@ -6750,7 +7666,7 @@ static __init int test_ringbuffer(void) rb_test_started = true; set_current_state(TASK_INTERRUPTIBLE); - /* Just run for 10 seconds */; + /* Just run for 10 seconds */ schedule_timeout(10 * HZ); kthread_stop(rb_hammer); |