Commit 2124de79 authored by Steven Rostedt (Google)'s avatar Steven Rostedt (Google)
Browse files

tracing: Implement creating an instance based on a given memory region 

Allow for creating a new instance by passing in an address and size to map
the ring buffer for the instance to.

This will allow features like a pstore memory mapped region to be used for
an tracing instance ring buffer that can be retrieved from one boot to the
next.

Link: https://lkml.kernel.org/r/20240612232025.692086240@goodmis.org



Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vineeth Pillai <vineeth@bitbyteword.org>
Cc: Youssef Esmat <youssefesmat@google.com>
Cc: Beau Belgrave <beaub@linux.microsoft.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Ross Zwisler <zwisler@google.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent b14d0329

kernel/trace/trace.c

+40 −10
Original line number Diff line number Diff line
@@ -4921,6 +4921,11 @@ static int tracing_open(struct inode *inode, struct file *file) 
static bool

trace_ok_for_array(struct tracer *t, struct trace_array *tr)

{

#ifdef CONFIG_TRACER_SNAPSHOT

	/* arrays with mapped buffer range do not have snapshots */

	if (tr->range_addr_start && t->use_max_tr)

		return false;

#endif

	return (tr->flags & TRACE_ARRAY_FL_GLOBAL) || t->allow_instances;

}
@@ -8664,11 +8669,13 @@ tracing_init_tracefs_percpu(struct trace_array *tr, long cpu) 
				tr, cpu, &tracing_entries_fops);



#ifdef CONFIG_TRACER_SNAPSHOT

	if (!tr->range_addr_start) {

		trace_create_cpu_file("snapshot", TRACE_MODE_WRITE, d_cpu,

				      tr, cpu, &snapshot_fops);



		trace_create_cpu_file("snapshot_raw", TRACE_MODE_READ, d_cpu,

				      tr, cpu, &snapshot_raw_fops);

	}

#endif

}
@@ -9205,7 +9212,18 @@ allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int size 


	buf->tr = tr;



	if (tr->range_addr_start && tr->range_addr_size) {

		buf->buffer = ring_buffer_alloc_range(size, rb_flags, 0,

						      tr->range_addr_start,

						      tr->range_addr_size);

		/*

		 * This is basically the same as a mapped buffer,

		 * with the same restrictions.

		 */

		tr->mapped++;

	} else {

		buf->buffer = ring_buffer_alloc(size, rb_flags);

	}

	if (!buf->buffer)

		return -ENOMEM;
@@ -9242,6 +9260,10 @@ static int allocate_trace_buffers(struct trace_array *tr, int size) 
		return ret;



#ifdef CONFIG_TRACER_MAX_TRACE

	/* Fix mapped buffer trace arrays do not have snapshot buffers */

	if (tr->range_addr_start)

		return 0;



	ret = allocate_trace_buffer(tr, &tr->max_buffer,

				    allocate_snapshot ? size : 1);

	if (MEM_FAIL(ret, "Failed to allocate trace buffer\n")) {
@@ -9342,7 +9364,9 @@ static int trace_array_create_dir(struct trace_array *tr) 
}



static struct trace_array *

trace_array_create_systems(const char *name, const char *systems)

trace_array_create_systems(const char *name, const char *systems,

			   unsigned long range_addr_start,

			   unsigned long range_addr_size)

{

	struct trace_array *tr;

	int ret;
@@ -9368,6 +9392,10 @@ trace_array_create_systems(const char *name, const char *systems) 
			goto out_free_tr;

	}



	/* Only for boot up memory mapped ring buffers */

	tr->range_addr_start = range_addr_start;

	tr->range_addr_size = range_addr_size;



	tr->trace_flags = global_trace.trace_flags & ~ZEROED_TRACE_FLAGS;



	cpumask_copy(tr->tracing_cpumask, cpu_all_mask);
@@ -9425,7 +9453,7 @@ trace_array_create_systems(const char *name, const char *systems) 


static struct trace_array *trace_array_create(const char *name)

{

	return trace_array_create_systems(name, NULL);

	return trace_array_create_systems(name, NULL, 0, 0);

}



static int instance_mkdir(const char *name)
@@ -9479,7 +9507,7 @@ struct trace_array *trace_array_get_by_name(const char *name, const char *system 
			goto out_unlock;

	}



	tr = trace_array_create_systems(name, systems);

	tr = trace_array_create_systems(name, systems, 0, 0);



	if (IS_ERR(tr))

		tr = NULL;
@@ -9672,8 +9700,10 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer) 
		MEM_FAIL(1, "Could not allocate function filter files");



#ifdef CONFIG_TRACER_SNAPSHOT

	if (!tr->range_addr_start) {

		trace_create_file("snapshot", TRACE_MODE_WRITE, d_tracer,

				  tr, &snapshot_fops);

	}

#endif



	trace_create_file("error_log", TRACE_MODE_WRITE, d_tracer,

kernel/trace/trace.h

+5 −1
Original line number Diff line number Diff line
@@ -336,7 +336,6 @@ struct trace_array { 
	bool			allocated_snapshot;

	spinlock_t		snapshot_trigger_lock;

	unsigned int		snapshot;

	unsigned int		mapped;

	unsigned long		max_latency;

#ifdef CONFIG_FSNOTIFY

	struct dentry		*d_max_latency;
@@ -344,6 +343,11 @@ struct trace_array { 
	struct irq_work		fsnotify_irqwork;

#endif

#endif

	/* The below is for memory mapped ring buffer */

	unsigned int		mapped;

	unsigned long		range_addr_start;

	unsigned long		range_addr_size;



	struct trace_pid_list	__rcu *filtered_pids;

	struct trace_pid_list	__rcu *filtered_no_pids;

	/*