Merge tag 'trace-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:

 - Allow kernel trace instance creation to specify what events are
   created

   Inside the kernel, a subsystem may create a tracing instance that it
   can use to send events to user space. This sub-system may not care
   about the thousands of events that exist in eventfs. Allow the
   sub-system to specify what sub-systems of events it cares about, and
   only those events are exposed to this instance.

 - Allow the ring buffer to be broken up into bigger sub-buffers than
   just the architecture page size.

   A new tracefs file called "buffer_subbuf_size_kb" is created. The
   user can now specify a minimum size the sub-buffer may be in
   kilobytes. Note, that the implementation currently make the
   sub-buffer size a power of 2 pages (1, 2, 4, 8, 16, ...) but the user
   only writes in kilobyte size, and the sub-buffer will be updated to
   the next size that it will can accommodate it. If the user writes in
   10, it will change the size to be 4 pages on x86 (16K), as that is
   the next available size that can hold 10K pages.

 - Update the debug output when a corrupt time is detected in the ring
   buffer. If the ring buffer detects inconsistent timestamps, there's a
   debug config options that will dump the contents of the meta data of
   the sub-buffer that is used for debugging. Add some more information
   to this dump that helps with debugging.

 - Add more timestamp debugging checks (only triggers when the config is
   enabled)

 - Increase the trace_seq iterator to 2 page sizes.

 - Allow strings written into tracefs_marker to be larger. Up to just
   under 2 page sizes (based on what trace_seq can hold).

 - Increase the trace_maker_raw write to be as big as a sub-buffer can
   hold.

 - Remove 32 bit time stamp logic, now that the rb_time_cmpxchg() has
   been removed.

 - More selftests were added.

 - Some code clean ups as well.

* tag 'trace-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (29 commits)
  ring-buffer: Remove stale comment from ring_buffer_size()
  tracing histograms: Simplify parse_actions() function
  tracing/selftests: Remove exec permissions from trace_marker.tc test
  ring-buffer: Use subbuf_order for buffer page masking
  tracing: Update subbuffer with kilobytes not page order
  ringbuffer/selftest: Add basic selftest to test changing subbuf order
  ring-buffer: Add documentation on the buffer_subbuf_order file
  ring-buffer: Just update the subbuffers when changing their allocation order
  ring-buffer: Keep the same size when updating the order
  tracing: Stop the tracing while changing the ring buffer subbuf size
  tracing: Update snapshot order along with main buffer order
  ring-buffer: Make sure the spare sub buffer used for reads has same size
  ring-buffer: Do no swap cpu buffers if order is different
  ring-buffer: Clear pages on error in ring_buffer_subbuf_order_set() failure
  ring-buffer: Read and write to ring buffers with custom sub buffer size
  ring-buffer: Set new size of the ring buffer sub page
  ring-buffer: Add interface for configuring trace sub buffer size
  ring-buffer: Page size per ring buffer
  ring-buffer: Have ring_buffer_print_page_header() be able to access ring_buffer_iter
  ring-buffer: Check if absolute timestamp goes backwards
  ...

1 files changed, 196 insertions, 38 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a0defe156b57..2a7c6fd934e9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1263,10 +1263,17 @@ static void set_buffer_entries(struct array_buffer *buf, unsigned long val);
 
 int tracing_alloc_snapshot_instance(struct trace_array *tr)
 {
+	int order;
 	int ret;
 
 	if (!tr->allocated_snapshot) {
 
+		/* Make the snapshot buffer have the same order as main buffer */
+		order = ring_buffer_subbuf_order_get(tr->array_buffer.buffer);
+		ret = ring_buffer_subbuf_order_set(tr->max_buffer.buffer, order);
+		if (ret < 0)
+			return ret;
+
 		/* allocate spare buffer */
 		ret = resize_buffer_duplicate_size(&tr->max_buffer,
 				   &tr->array_buffer, RING_BUFFER_ALL_CPUS);
@@ -1286,6 +1293,7 @@ static void free_snapshot(struct trace_array *tr)
 	 * The max_tr ring buffer has some state (e.g. ring->clock) and
 	 * we want preserve it.
 	 */
+	ring_buffer_subbuf_order_set(tr->max_buffer.buffer, 0);
 	ring_buffer_resize(tr->max_buffer.buffer, 1, RING_BUFFER_ALL_CPUS);
 	set_buffer_entries(&tr->max_buffer, 1);
 	tracing_reset_online_cpus(&tr->max_buffer);
@@ -3767,7 +3775,7 @@ static bool trace_safe_str(struct trace_iterator *iter, const char *str,
 
 	/* OK if part of the temp seq buffer */
 	if ((addr >= (unsigned long)iter->tmp_seq.buffer) &&
-	    (addr < (unsigned long)iter->tmp_seq.buffer + PAGE_SIZE))
+	    (addr < (unsigned long)iter->tmp_seq.buffer + TRACE_SEQ_BUFFER_SIZE))
 		return true;
 
 	/* Core rodata can not be freed */
@@ -5032,7 +5040,7 @@ static int tracing_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
-static int tracing_release_generic_tr(struct inode *inode, struct file *file)
+int tracing_release_generic_tr(struct inode *inode, struct file *file)
 {
 	struct trace_array *tr = inode->i_private;
 
@@ -6946,8 +6954,8 @@ waitagain:
 		goto out;
 	}
 
-	if (cnt >= PAGE_SIZE)
-		cnt = PAGE_SIZE - 1;
+	if (cnt >= TRACE_SEQ_BUFFER_SIZE)
+		cnt = TRACE_SEQ_BUFFER_SIZE - 1;
 
 	/* reset all but tr, trace, and overruns */
 	trace_iterator_reset(iter);
@@ -7292,8 +7300,9 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
 	enum event_trigger_type tt = ETT_NONE;
 	struct trace_buffer *buffer;
 	struct print_entry *entry;
+	int meta_size;
 	ssize_t written;
-	int size;
+	size_t size;
 	int len;
 
 /* Used in tracing_mark_raw_write() as well */
@@ -7306,23 +7315,44 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
 	if (!(tr->trace_flags & TRACE_ITER_MARKERS))
 		return -EINVAL;
 
-	if (cnt > TRACE_BUF_SIZE)
-		cnt = TRACE_BUF_SIZE;
-
-	BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE);
+	if ((ssize_t)cnt < 0)
+		return -EINVAL;
 
-	size = sizeof(*entry) + cnt + 2; /* add '\0' and possible '\n' */
+	meta_size = sizeof(*entry) + 2;  /* add '\0' and possible '\n' */
+ again:
+	size = cnt + meta_size;
 
 	/* If less than "<faulted>", then make sure we can still add that */
 	if (cnt < FAULTED_SIZE)
 		size += FAULTED_SIZE - cnt;
 
+	if (size > TRACE_SEQ_BUFFER_SIZE) {
+		cnt -= size - TRACE_SEQ_BUFFER_SIZE;
+		goto again;
+	}
+
 	buffer = tr->array_buffer.buffer;
 	event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
 					    tracing_gen_ctx());
-	if (unlikely(!event))
+	if (unlikely(!event)) {
+		/*
+		 * If the size was greater than what was allowed, then
+		 * make it smaller and try again.
+		 */
+		if (size > ring_buffer_max_event_size(buffer)) {
+			/* cnt < FAULTED size should never be bigger than max */
+			if (WARN_ON_ONCE(cnt < FAULTED_SIZE))
+				return -EBADF;
+			cnt = ring_buffer_max_event_size(buffer) - meta_size;
+			/* The above should only happen once */
+			if (WARN_ON_ONCE(cnt + meta_size == size))
+				return -EBADF;
+			goto again;
+		}
+
 		/* Ring buffer disabled, return as if not open for write */
 		return -EBADF;
+	}
 
 	entry = ring_buffer_event_data(event);
 	entry->ip = _THIS_IP_;
@@ -7357,9 +7387,6 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
 	return written;
 }
 
-/* Limit it for now to 3K (including tag) */
-#define RAW_DATA_MAX_SIZE (1024*3)
-
 static ssize_t
 tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
 					size_t cnt, loff_t *fpos)
@@ -7381,19 +7408,18 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
 		return -EINVAL;
 
 	/* The marker must at least have a tag id */
-	if (cnt < sizeof(unsigned int) || cnt > RAW_DATA_MAX_SIZE)
+	if (cnt < sizeof(unsigned int))
 		return -EINVAL;
 
-	if (cnt > TRACE_BUF_SIZE)
-		cnt = TRACE_BUF_SIZE;
-
-	BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE);
-
 	size = sizeof(*entry) + cnt;
 	if (cnt < FAULT_SIZE_ID)
 		size += FAULT_SIZE_ID - cnt;
 
 	buffer = tr->array_buffer.buffer;
+
+	if (size > ring_buffer_max_event_size(buffer))
+		return -EINVAL;
+
 	event = __trace_buffer_lock_reserve(buffer, TRACE_RAW_DATA, size,
 					    tracing_gen_ctx());
 	if (!event)
@@ -7578,6 +7604,7 @@ struct ftrace_buffer_info {
 	struct trace_iterator	iter;
 	void			*spare;
 	unsigned int		spare_cpu;
+	unsigned int		spare_size;
 	unsigned int		read;
 };
 
@@ -8282,6 +8309,8 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 {
 	struct ftrace_buffer_info *info = filp->private_data;
 	struct trace_iterator *iter = &info->iter;
+	void *trace_data;
+	int page_size;
 	ssize_t ret = 0;
 	ssize_t size;
 
@@ -8293,6 +8322,17 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 		return -EBUSY;
 #endif
 
+	page_size = ring_buffer_subbuf_size_get(iter->array_buffer->buffer);
+
+	/* Make sure the spare matches the current sub buffer size */
+	if (info->spare) {
+		if (page_size != info->spare_size) {
+			ring_buffer_free_read_page(iter->array_buffer->buffer,
+						   info->spare_cpu, info->spare);
+			info->spare = NULL;
+		}
+	}
+
 	if (!info->spare) {
 		info->spare = ring_buffer_alloc_read_page(iter->array_buffer->buffer,
 							  iter->cpu_file);
@@ -8301,19 +8341,20 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 			info->spare = NULL;
 		} else {
 			info->spare_cpu = iter->cpu_file;
+			info->spare_size = page_size;
 		}
 	}
 	if (!info->spare)
 		return ret;
 
 	/* Do we have previous read data to read? */
-	if (info->read < PAGE_SIZE)
+	if (info->read < page_size)
 		goto read;
 
  again:
 	trace_access_lock(iter->cpu_file);
 	ret = ring_buffer_read_page(iter->array_buffer->buffer,
-				    &info->spare,
+				    info->spare,
 				    count,
 				    iter->cpu_file, 0);
 	trace_access_unlock(iter->cpu_file);
@@ -8334,11 +8375,11 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 
 	info->read = 0;
  read:
-	size = PAGE_SIZE - info->read;
+	size = page_size - info->read;
 	if (size > count)
 		size = count;
-
-	ret = copy_to_user(ubuf, info->spare + info->read, size);
+	trace_data = ring_buffer_read_page_data(info->spare);
+	ret = copy_to_user(ubuf, trace_data + info->read, size);
 	if (ret == size)
 		return -EFAULT;
 
@@ -8449,6 +8490,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 		.spd_release	= buffer_spd_release,
 	};
 	struct buffer_ref *ref;
+	int page_size;
 	int entries, i;
 	ssize_t ret = 0;
 
@@ -8457,13 +8499,14 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 		return -EBUSY;
 #endif
 
-	if (*ppos & (PAGE_SIZE - 1))
+	page_size = ring_buffer_subbuf_size_get(iter->array_buffer->buffer);
+	if (*ppos & (page_size - 1))
 		return -EINVAL;
 
-	if (len & (PAGE_SIZE - 1)) {
-		if (len < PAGE_SIZE)
+	if (len & (page_size - 1)) {
+		if (len < page_size)
 			return -EINVAL;
-		len &= PAGE_MASK;
+		len &= (~(page_size - 1));
 	}
 
 	if (splice_grow_spd(pipe, &spd))
@@ -8473,7 +8516,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 	trace_access_lock(iter->cpu_file);
 	entries = ring_buffer_entries_cpu(iter->array_buffer->buffer, iter->cpu_file);
 
-	for (i = 0; i < spd.nr_pages_max && len && entries; i++, len -= PAGE_SIZE) {
+	for (i = 0; i < spd.nr_pages_max && len && entries; i++, len -= page_size) {
 		struct page *page;
 		int r;
 
@@ -8494,7 +8537,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 		}
 		ref->cpu = iter->cpu_file;
 
-		r = ring_buffer_read_page(ref->buffer, &ref->page,
+		r = ring_buffer_read_page(ref->buffer, ref->page,
 					  len, iter->cpu_file, 1);
 		if (r < 0) {
 			ring_buffer_free_read_page(ref->buffer, ref->cpu,
@@ -8503,14 +8546,14 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 			break;
 		}
 
-		page = virt_to_page(ref->page);
+		page = virt_to_page(ring_buffer_read_page_data(ref->page));
 
 		spd.pages[i] = page;
-		spd.partial[i].len = PAGE_SIZE;
+		spd.partial[i].len = page_size;
 		spd.partial[i].offset = 0;
 		spd.partial[i].private = (unsigned long)ref;
 		spd.nr_pages++;
-		*ppos += PAGE_SIZE;
+		*ppos += page_size;
 
 		entries = ring_buffer_entries_cpu(iter->array_buffer->buffer, iter->cpu_file);
 	}
@@ -9354,6 +9397,103 @@ static const struct file_operations buffer_percent_fops = {
 	.llseek		= default_llseek,
 };
 
+static ssize_t
+buffer_subbuf_size_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+	struct trace_array *tr = filp->private_data;
+	size_t size;
+	char buf[64];
+	int order;
+	int r;
+
+	order = ring_buffer_subbuf_order_get(tr->array_buffer.buffer);
+	size = (PAGE_SIZE << order) / 1024;
+
+	r = sprintf(buf, "%zd\n", size);
+
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+buffer_subbuf_size_write(struct file *filp, const char __user *ubuf,
+			 size_t cnt, loff_t *ppos)
+{
+	struct trace_array *tr = filp->private_data;
+	unsigned long val;
+	int old_order;
+	int order;
+	int pages;
+	int ret;
+
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+	if (ret)
+		return ret;
+
+	val *= 1024; /* value passed in is in KB */
+
+	pages = DIV_ROUND_UP(val, PAGE_SIZE);
+	order = fls(pages - 1);
+
+	/* limit between 1 and 128 system pages */
+	if (order < 0 || order > 7)
+		return -EINVAL;
+
+	/* Do not allow tracing while changing the order of the ring buffer */
+	tracing_stop_tr(tr);
+
+	old_order = ring_buffer_subbuf_order_get(tr->array_buffer.buffer);
+	if (old_order == order)
+		goto out;
+
+	ret = ring_buffer_subbuf_order_set(tr->array_buffer.buffer, order);
+	if (ret)
+		goto out;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+
+	if (!tr->allocated_snapshot)
+		goto out_max;
+
+	ret = ring_buffer_subbuf_order_set(tr->max_buffer.buffer, order);
+	if (ret) {
+		/* Put back the old order */
+		cnt = ring_buffer_subbuf_order_set(tr->array_buffer.buffer, old_order);
+		if (WARN_ON_ONCE(cnt)) {
+			/*
+			 * AARGH! We are left with different orders!
+			 * The max buffer is our "snapshot" buffer.
+			 * When a tracer needs a snapshot (one of the
+			 * latency tracers), it swaps the max buffer
+			 * with the saved snap shot. We succeeded to
+			 * update the order of the main buffer, but failed to
+			 * update the order of the max buffer. But when we tried
+			 * to reset the main buffer to the original size, we
+			 * failed there too. This is very unlikely to
+			 * happen, but if it does, warn and kill all
+			 * tracing.
+			 */
+			tracing_disabled = 1;
+		}
+		goto out;
+	}
+ out_max:
+#endif
+	(*ppos)++;
+ out:
+	if (ret)
+		cnt = ret;
+	tracing_start_tr(tr);
+	return cnt;
+}
+
+static const struct file_operations buffer_subbuf_size_fops = {
+	.open		= tracing_open_generic_tr,
+	.read		= buffer_subbuf_size_read,
+	.write		= buffer_subbuf_size_write,
+	.release	= tracing_release_generic_tr,
+	.llseek		= default_llseek,
+};
+
 static struct dentry *trace_instance_dir;
 
 static void
@@ -9504,7 +9644,8 @@ static int trace_array_create_dir(struct trace_array *tr)
 	return ret;
 }
 
-static struct trace_array *trace_array_create(const char *name)
+static struct trace_array *
+trace_array_create_systems(const char *name, const char *systems)
 {
 	struct trace_array *tr;
 	int ret;
@@ -9524,6 +9665,12 @@ static struct trace_array *trace_array_create(const char *name)
 	if (!zalloc_cpumask_var(&tr->pipe_cpumask, GFP_KERNEL))
 		goto out_free_tr;
 
+	if (systems) {
+		tr->system_names = kstrdup_const(systems, GFP_KERNEL);
+		if (!tr->system_names)
+			goto out_free_tr;
+	}
+
 	tr->trace_flags = global_trace.trace_flags & ~ZEROED_TRACE_FLAGS;
 
 	cpumask_copy(tr->tracing_cpumask, cpu_all_mask);
@@ -9570,12 +9717,18 @@ static struct trace_array *trace_array_create(const char *name)
 	free_trace_buffers(tr);
 	free_cpumask_var(tr->pipe_cpumask);
 	free_cpumask_var(tr->tracing_cpumask);
+	kfree_const(tr->system_names);
 	kfree(tr->name);
 	kfree(tr);
 
 	return ERR_PTR(ret);
 }
 
+static struct trace_array *trace_array_create(const char *name)
+{
+	return trace_array_create_systems(name, NULL);
+}
+
 static int instance_mkdir(const char *name)
 {
 	struct trace_array *tr;
@@ -9601,6 +9754,7 @@ out_unlock:
 /**
  * trace_array_get_by_name - Create/Lookup a trace array, given its name.
  * @name: The name of the trace array to be looked up/created.
+ * @systems: A list of systems to create event directories for (NULL for all)
  *
  * Returns pointer to trace array with given name.
  * NULL, if it cannot be created.
@@ -9614,7 +9768,7 @@ out_unlock:
  * trace_array_put() is called, user space can not delete it.
  *
  */
-struct trace_array *trace_array_get_by_name(const char *name)
+struct trace_array *trace_array_get_by_name(const char *name, const char *systems)
 {
 	struct trace_array *tr;
 
@@ -9626,7 +9780,7 @@ struct trace_array *trace_array_get_by_name(const char *name)
 			goto out_unlock;
 	}
 
-	tr = trace_array_create(name);
+	tr = trace_array_create_systems(name, systems);
 
 	if (IS_ERR(tr))
 		tr = NULL;
@@ -9673,6 +9827,7 @@ static int __remove_instance(struct trace_array *tr)
 
 	free_cpumask_var(tr->pipe_cpumask);
 	free_cpumask_var(tr->tracing_cpumask);
+	kfree_const(tr->system_names);
 	kfree(tr->name);
 	kfree(tr);
 
@@ -9805,6 +9960,9 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 	trace_create_file("buffer_percent", TRACE_MODE_WRITE, d_tracer,
 			tr, &buffer_percent_fops);
 
+	trace_create_file("buffer_subbuf_size_kb", TRACE_MODE_WRITE, d_tracer,
+			  tr, &buffer_subbuf_size_fops);
+
 	create_trace_options_dir(tr);
 
 #ifdef CONFIG_TRACER_MAX_TRACE
@@ -10391,7 +10549,7 @@ __init static void enable_instances(void)
 		if (IS_ENABLED(CONFIG_TRACER_MAX_TRACE))
 			do_allocate_snapshot(tok);
 
-		tr = trace_array_get_by_name(tok);
+		tr = trace_array_get_by_name(tok, NULL);
 		if (!tr) {
 			pr_warn("Failed to create instance buffer %s\n", curr_str);
 			continue;