Merge tag 'trace-ring-buffer-v6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull ring-buffer updates from Steven Rostedt:

 - tracing/ring-buffer: persistent buffer across reboots

   This allows for the tracing instance ring buffer to stay persistent
   across reboots. The way this is done is by adding to the kernel
   command line:

     trace_instance=boot_map@0x285400000:12M

   This will reserve 12 megabytes at the address 0x285400000, and then
   map the tracing instance "boot_map" ring buffer to that memory. This
   will appear as a normal instance in the tracefs system:

     /sys/kernel/tracing/instances/boot_map

   A user could enable tracing in that instance, and on reboot or kernel
   crash, if the memory is not wiped by the firmware, it will recreate
   the trace in that instance. For example, if one was debugging a
   shutdown of a kernel reboot:

     # cd /sys/kernel/tracing
     # echo function > instances/boot_map/current_tracer
     # reboot
     [..]
     # cd /sys/kernel/tracing
     # tail instances/boot_map/trace
           swapper/0-1       [000] d..1.   164.549800: restore_boot_irq_mode <-native_machine_shutdown
           swapper/0-1       [000] d..1.   164.549801: native_restore_boot_irq_mode <-native_machine_shutdown
           swapper/0-1       [000] d..1.   164.549802: disconnect_bsp_APIC <-native_machine_shutdown
           swapper/0-1       [000] d..1.   164.549811: hpet_disable <-native_machine_shutdown
           swapper/0-1       [000] d..1.   164.549812: iommu_shutdown_noop <-native_machine_restart
           swapper/0-1       [000] d..1.   164.549813: native_machine_emergency_restart <-__do_sys_reboot
           swapper/0-1       [000] d..1.   164.549813: tboot_shutdown <-native_machine_emergency_restart
           swapper/0-1       [000] d..1.   164.549820: acpi_reboot <-native_machine_emergency_restart
           swapper/0-1       [000] d..1.   164.549821: acpi_reset <-acpi_reboot
           swapper/0-1       [000] d..1.   164.549822: acpi_os_write_port <-acpi_reboot

   On reboot, the buffer is examined to make sure it is valid. The
   validation check even steps through every event to make sure the meta
   data of the event is correct. If any test fails, it will simply reset
   the buffer, and the buffer will be empty on boot.

 - Allow the tracing persistent boot buffer to use the "reserve_mem"
   option

   Instead of having the admin find a physical address to store the
   persistent buffer, which can be very tedious if they have to
   administrate several different machines, allow them to use the
   "reserve_mem" option that will find a location for them. It is not as
   reliable because of KASLR, as the loading of the kernel in different
   locations can cause the memory allocated to be inconsistent. Booting
   with "nokaslr" can make reserve_mem more reliable.

 - Have function graph tracer handle offsets from a previous boot.

   The ring buffer output from a previous boot may have different
   addresses due to kaslr. Have the function graph tracer handle these
   by using the delta from the previous boot to the new boot address
   space.

 - Only reset the saved meta offset when the buffer is started or reset

   In the persistent memory meta data, it holds the previous address
   space information, so that it can calculate the delta to have
   function tracing work. But this gets updated after being read to hold
   the new address space. But if the buffer isn't used for that boot, on
   reboot, the delta is now calculated from the previous boot and not
   the boot that holds the data in the ring buffer. This causes the
   functions not to be shown. Do not save the address space information
   of the current kernel until it is being recorded.

 - Add a magic variable to test the valid meta data

   Add a magic variable in the meta data that can also be used for
   validation. The validator of the previous buffer doesn't need this
   magic data, but it can be used if the meta data is changed by a new
   kernel, which may have the same format that passes the validator but
   is used differently. This magic number can also be used as a
   "versioning" of the meta data.

 - Align user space mapped ring buffer sub buffers to improve TLB
   entries

   Linus mentioned that the mapped ring buffer sub buffers were
   misaligned between the meta page and the sub-buffers, so that if the
   sub-buffers were bigger than PAGE_SIZE, it wouldn't allow the TLB to
   use bigger entries.

 - Add new kernel command line "traceoff" to disable tracing on boot for
   instances

   If tracing is enabled for a boot instance, there needs a way to be
   able to disable it on boot so that new events do not get entered into
   the ring buffer and be mixed with events from a previous boot, as
   that can be confusing.

 - Allow trace_printk() to go to other instances

   Currently, trace_printk() can only go to the top level instance. When
   debugging with a persistent buffer, it is really useful to be able to
   add trace_printk() to go to that buffer, so that you have access to
   them after a crash.

 - Do not use "bin_printk()" for traces to a boot instance

   The bin_printk() saves only a pointer to the printk format in the
   ring buffer, as the reader of the buffer can still have access to it.
   But this is not the case if the buffer is from a previous boot. If
   the trace_printk() is going to a "persistent" buffer, it will use the
   slower version that writes the printk format into the buffer.

 - Add command line option to allow trace_printk() to go to an instance

   Allow the kernel command line to define which instance the
   trace_printk() goes to, instead of forcing the admin to set it for
   every boot via the tracefs options.

 - Start a document that explains how to use tracefs to debug the kernel

 - Add some more kernel selftests to test user mapped ring buffer

* tag 'trace-ring-buffer-v6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (28 commits)
  selftests/ring-buffer: Handle meta-page bigger than the system
  selftests/ring-buffer: Verify the entire meta-page padding
  tracing/Documentation: Start a document on how to debug with tracing
  tracing: Add option to set an instance to be the trace_printk destination
  tracing: Have trace_printk not use binary prints if boot buffer
  tracing: Allow trace_printk() to go to other instance buffers
  tracing: Add "traceoff" flag to boot time tracing instances
  ring-buffer: Align meta-page to sub-buffers for improved TLB usage
  ring-buffer: Add magic and struct size to boot up meta data
  ring-buffer: Don't reset persistent ring-buffer meta saved addresses
  tracing/fgraph: Have fgraph handle previous boot function addresses
  tracing: Allow boot instances to use reserve_mem boot memory
  tracing: Fix ifdef of snapshots to not prevent last_boot_info file
  ring-buffer: Use vma_pages() helper function
  tracing: Fix NULL vs IS_ERR() check in enable_instances()
  tracing: Add last boot delta offset for stack traces
  tracing: Update function tracing output for previous boot buffer
  tracing: Handle old buffer mappings for event strings and functions
  tracing/ring-buffer: Add last_boot_info file to boot instance
  ring-buffer: Save text and data locations in mapped meta data
  ...

1 files changed, 338 insertions, 34 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c3b2c7dfadef..b4f348b4653f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -482,7 +482,7 @@ EXPORT_SYMBOL_GPL(unregister_ftrace_export);
 	 TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO |		\
 	 TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE |			\
 	 TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS |			\
-	 TRACE_ITER_HASH_PTR)
+	 TRACE_ITER_HASH_PTR | TRACE_ITER_TRACE_PRINTK)
 
 /* trace_options that are only supported by global_trace */
 #define TOP_LEVEL_TRACE_FLAGS (TRACE_ITER_PRINTK |			\
@@ -490,7 +490,7 @@ EXPORT_SYMBOL_GPL(unregister_ftrace_export);
 
 /* trace_flags that are default zero for instances */
 #define ZEROED_TRACE_FLAGS \
-	(TRACE_ITER_EVENT_FORK | TRACE_ITER_FUNC_FORK)
+	(TRACE_ITER_EVENT_FORK | TRACE_ITER_FUNC_FORK | TRACE_ITER_TRACE_PRINTK)
 
 /*
  * The global_trace is the descriptor that holds the top-level tracing
@@ -500,6 +500,29 @@ static struct trace_array global_trace = {
 	.trace_flags = TRACE_DEFAULT_FLAGS,
 };
 
+static struct trace_array *printk_trace = &global_trace;
+
+static __always_inline bool printk_binsafe(struct trace_array *tr)
+{
+	/*
+	 * The binary format of traceprintk can cause a crash if used
+	 * by a buffer from another boot. Force the use of the
+	 * non binary version of trace_printk if the trace_printk
+	 * buffer is a boot mapped ring buffer.
+	 */
+	return !(tr->flags & TRACE_ARRAY_FL_BOOT);
+}
+
+static void update_printk_trace(struct trace_array *tr)
+{
+	if (printk_trace == tr)
+		return;
+
+	printk_trace->trace_flags &= ~TRACE_ITER_TRACE_PRINTK;
+	printk_trace = tr;
+	tr->trace_flags |= TRACE_ITER_TRACE_PRINTK;
+}
+
 void trace_set_ring_buffer_expanded(struct trace_array *tr)
 {
 	if (!tr)
@@ -1117,7 +1140,7 @@ EXPORT_SYMBOL_GPL(__trace_array_puts);
  */
 int __trace_puts(unsigned long ip, const char *str, int size)
 {
-	return __trace_array_puts(&global_trace, ip, str, size);
+	return __trace_array_puts(printk_trace, ip, str, size);
 }
 EXPORT_SYMBOL_GPL(__trace_puts);
 
@@ -1128,6 +1151,7 @@ EXPORT_SYMBOL_GPL(__trace_puts);
  */
 int __trace_bputs(unsigned long ip, const char *str)
 {
+	struct trace_array *tr = READ_ONCE(printk_trace);
 	struct ring_buffer_event *event;
 	struct trace_buffer *buffer;
 	struct bputs_entry *entry;
@@ -1135,14 +1159,17 @@ int __trace_bputs(unsigned long ip, const char *str)
 	int size = sizeof(struct bputs_entry);
 	int ret = 0;
 
-	if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
+	if (!printk_binsafe(tr))
+		return __trace_puts(ip, str, strlen(str));
+
+	if (!(tr->trace_flags & TRACE_ITER_PRINTK))
 		return 0;
 
 	if (unlikely(tracing_selftest_running || tracing_disabled))
 		return 0;
 
 	trace_ctx = tracing_gen_ctx();
-	buffer = global_trace.array_buffer.buffer;
+	buffer = tr->array_buffer.buffer;
 
 	ring_buffer_nest_start(buffer);
 	event = __trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,
@@ -1155,7 +1182,7 @@ int __trace_bputs(unsigned long ip, const char *str)
 	entry->str			= str;
 
 	__buffer_unlock_commit(buffer, event);
-	ftrace_trace_stack(&global_trace, buffer, trace_ctx, 4, NULL);
+	ftrace_trace_stack(tr, buffer, trace_ctx, 4, NULL);
 
 	ret = 1;
  out:
@@ -3021,7 +3048,7 @@ void trace_dump_stack(int skip)
 	/* Skip 1 to skip this function. */
 	skip++;
 #endif
-	__ftrace_trace_stack(global_trace.array_buffer.buffer,
+	__ftrace_trace_stack(printk_trace->array_buffer.buffer,
 			     tracing_gen_ctx(), skip, NULL);
 }
 EXPORT_SYMBOL_GPL(trace_dump_stack);
@@ -3240,12 +3267,15 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
 	struct trace_event_call *call = &event_bprint;
 	struct ring_buffer_event *event;
 	struct trace_buffer *buffer;
-	struct trace_array *tr = &global_trace;
+	struct trace_array *tr = READ_ONCE(printk_trace);
 	struct bprint_entry *entry;
 	unsigned int trace_ctx;
 	char *tbuffer;
 	int len = 0, size;
 
+	if (!printk_binsafe(tr))
+		return trace_vprintk(ip, fmt, args);
+
 	if (unlikely(tracing_selftest_running || tracing_disabled))
 		return 0;
 
@@ -3338,7 +3368,7 @@ __trace_array_vprintk(struct trace_buffer *buffer,
 	memcpy(&entry->buf, tbuffer, len + 1);
 	if (!call_filter_check_discard(call, entry, buffer, event)) {
 		__buffer_unlock_commit(buffer, event);
-		ftrace_trace_stack(&global_trace, buffer, trace_ctx, 6, NULL);
+		ftrace_trace_stack(printk_trace, buffer, trace_ctx, 6, NULL);
 	}
 
 out:
@@ -3434,7 +3464,7 @@ int trace_array_printk_buf(struct trace_buffer *buffer,
 	int ret;
 	va_list ap;
 
-	if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
+	if (!(printk_trace->trace_flags & TRACE_ITER_PRINTK))
 		return 0;
 
 	va_start(ap, fmt);
@@ -3446,7 +3476,7 @@ int trace_array_printk_buf(struct trace_buffer *buffer,
 __printf(2, 0)
 int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
 {
-	return trace_array_vprintk(&global_trace, ip, fmt, args);
+	return trace_array_vprintk(printk_trace, ip, fmt, args);
 }
 EXPORT_SYMBOL_GPL(trace_vprintk);
 
@@ -3667,8 +3697,11 @@ static void test_can_verify(void)
 void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 			 va_list ap)
 {
+	long text_delta = iter->tr->text_delta;
+	long data_delta = iter->tr->data_delta;
 	const char *p = fmt;
 	const char *str;
+	bool good;
 	int i, j;
 
 	if (WARN_ON_ONCE(!fmt))
@@ -3687,7 +3720,10 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 
 		j = 0;
 
-		/* We only care about %s and variants */
+		/*
+		 * We only care about %s and variants
+		 * as well as %p[sS] if delta is non-zero
+		 */
 		for (i = 0; p[i]; i++) {
 			if (i + 1 >= iter->fmt_size) {
 				/*
@@ -3716,6 +3752,11 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 				}
 				if (p[i+j] == 's')
 					break;
+
+				if (text_delta && p[i+1] == 'p' &&
+				    ((p[i+2] == 's' || p[i+2] == 'S')))
+					break;
+
 				star = false;
 			}
 			j = 0;
@@ -3729,6 +3770,24 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 		iter->fmt[i] = '\0';
 		trace_seq_vprintf(&iter->seq, iter->fmt, ap);
 
+		/* Add delta to %pS pointers */
+		if (p[i+1] == 'p') {
+			unsigned long addr;
+			char fmt[4];
+
+			fmt[0] = '%';
+			fmt[1] = 'p';
+			fmt[2] = p[i+2]; /* Either %ps or %pS */
+			fmt[3] = '\0';
+
+			addr = va_arg(ap, unsigned long);
+			addr += text_delta;
+			trace_seq_printf(&iter->seq, fmt, (void *)addr);
+
+			p += i + 3;
+			continue;
+		}
+
 		/*
 		 * If iter->seq is full, the above call no longer guarantees
 		 * that ap is in sync with fmt processing, and further calls
@@ -3747,6 +3806,14 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 		/* The ap now points to the string data of the %s */
 		str = va_arg(ap, const char *);
 
+		good = trace_safe_str(iter, str, star, len);
+
+		/* Could be from the last boot */
+		if (data_delta && !good) {
+			str += data_delta;
+			good = trace_safe_str(iter, str, star, len);
+		}
+
 		/*
 		 * If you hit this warning, it is likely that the
 		 * trace event in question used %s on a string that
@@ -3756,8 +3823,7 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 		 * instead. See samples/trace_events/trace-events-sample.h
 		 * for reference.
 		 */
-		if (WARN_ONCE(!trace_safe_str(iter, str, star, len),
-			      "fmt: '%s' current_buffer: '%s'",
+		if (WARN_ONCE(!good, "fmt: '%s' current_buffer: '%s'",
 			      fmt, seq_buf_str(&iter->seq.seq))) {
 			int ret;
 
@@ -4919,6 +4985,11 @@ 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;
 }
 
@@ -5011,7 +5082,7 @@ static int show_traces_open(struct inode *inode, struct file *file)
 	return 0;
 }
 
-static int show_traces_release(struct inode *inode, struct file *file)
+static int tracing_seq_release(struct inode *inode, struct file *file)
 {
 	struct trace_array *tr = inode->i_private;
 
@@ -5052,7 +5123,7 @@ static const struct file_operations show_traces_fops = {
 	.open		= show_traces_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
-	.release	= show_traces_release,
+	.release	= tracing_seq_release,
 };
 
 static ssize_t
@@ -5237,7 +5308,8 @@ int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set)
 int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
 {
 	if ((mask == TRACE_ITER_RECORD_TGID) ||
-	    (mask == TRACE_ITER_RECORD_CMD))
+	    (mask == TRACE_ITER_RECORD_CMD) ||
+	    (mask == TRACE_ITER_TRACE_PRINTK))
 		lockdep_assert_held(&event_mutex);
 
 	/* do nothing if flag is already set */
@@ -5249,6 +5321,25 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
 		if (tr->current_trace->flag_changed(tr, mask, !!enabled))
 			return -EINVAL;
 
+	if (mask == TRACE_ITER_TRACE_PRINTK) {
+		if (enabled) {
+			update_printk_trace(tr);
+		} else {
+			/*
+			 * The global_trace cannot clear this.
+			 * It's flag only gets cleared if another instance sets it.
+			 */
+			if (printk_trace == &global_trace)
+				return -EINVAL;
+			/*
+			 * An instance must always have it set.
+			 * by default, that's the global_trace instane.
+			 */
+			if (printk_trace == tr)
+				update_printk_trace(&global_trace);
+		}
+	}
+
 	if (enabled)
 		tr->trace_flags |= mask;
 	else
@@ -6034,6 +6125,18 @@ out:
 	return ret;
 }
 
+static void update_last_data(struct trace_array *tr)
+{
+	if (!tr->text_delta && !tr->data_delta)
+		return;
+
+	/* Clear old data */
+	tracing_reset_online_cpus(&tr->array_buffer);
+
+	/* Using current data now */
+	tr->text_delta = 0;
+	tr->data_delta = 0;
+}
 
 /**
  * tracing_update_buffers - used by tracing facility to expand ring buffers
@@ -6051,6 +6154,9 @@ int tracing_update_buffers(struct trace_array *tr)
 	int ret = 0;
 
 	mutex_lock(&trace_types_lock);
+
+	update_last_data(tr);
+
 	if (!tr->ring_buffer_expanded)
 		ret = __tracing_resize_ring_buffer(tr, trace_buf_size,
 						RING_BUFFER_ALL_CPUS);
@@ -6106,6 +6212,8 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf)
 
 	mutex_lock(&trace_types_lock);
 
+	update_last_data(tr);
+
 	if (!tr->ring_buffer_expanded) {
 		ret = __tracing_resize_ring_buffer(tr, trace_buf_size,
 						RING_BUFFER_ALL_CPUS);
@@ -6854,6 +6962,37 @@ tracing_total_entries_read(struct file *filp, char __user *ubuf,
 }
 
 static ssize_t
+tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+	struct trace_array *tr = filp->private_data;
+	struct seq_buf seq;
+	char buf[64];
+
+	seq_buf_init(&seq, buf, 64);
+
+	seq_buf_printf(&seq, "text delta:\t%ld\n", tr->text_delta);
+	seq_buf_printf(&seq, "data delta:\t%ld\n", tr->data_delta);
+
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, seq_buf_used(&seq));
+}
+
+static int tracing_buffer_meta_open(struct inode *inode, struct file *filp)
+{
+	struct trace_array *tr = inode->i_private;
+	int cpu = tracing_get_cpu(inode);
+	int ret;
+
+	ret = tracing_check_open_get_tr(tr);
+	if (ret)
+		return ret;
+
+	ret = ring_buffer_meta_seq_init(filp, tr->array_buffer.buffer, cpu);
+	if (ret < 0)
+		__trace_array_put(tr);
+	return ret;
+}
+
+static ssize_t
 tracing_free_buffer_write(struct file *filp, const char __user *ubuf,
 			  size_t cnt, loff_t *ppos)
 {
@@ -7429,6 +7568,13 @@ static const struct file_operations tracing_entries_fops = {
 	.release	= tracing_release_generic_tr,
 };
 
+static const struct file_operations tracing_buffer_meta_fops = {
+	.open		= tracing_buffer_meta_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= tracing_seq_release,
+};
+
 static const struct file_operations tracing_total_entries_fops = {
 	.open		= tracing_open_generic_tr,
 	.read		= tracing_total_entries_read,
@@ -7469,6 +7615,13 @@ static const struct file_operations trace_time_stamp_mode_fops = {
 	.release	= tracing_single_release_tr,
 };
 
+static const struct file_operations last_boot_fops = {
+	.open		= tracing_open_generic_tr,
+	.read		= tracing_last_boot_read,
+	.llseek		= generic_file_llseek,
+	.release	= tracing_release_generic_tr,
+};
+
 #ifdef CONFIG_TRACER_SNAPSHOT
 static const struct file_operations snapshot_fops = {
 	.open		= tracing_snapshot_open,
@@ -8661,12 +8814,17 @@ tracing_init_tracefs_percpu(struct trace_array *tr, long cpu)
 	trace_create_cpu_file("buffer_size_kb", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &tracing_entries_fops);
 
+	if (tr->range_addr_start)
+		trace_create_cpu_file("buffer_meta", TRACE_MODE_READ, d_cpu,
+				      tr, cpu, &tracing_buffer_meta_fops);
 #ifdef CONFIG_TRACER_SNAPSHOT
-	trace_create_cpu_file("snapshot", TRACE_MODE_WRITE, d_cpu,
-				tr, cpu, &snapshot_fops);
+	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);
+		trace_create_cpu_file("snapshot_raw", TRACE_MODE_READ, d_cpu,
+				      tr, cpu, &snapshot_raw_fops);
+	}
 #endif
 }
 
@@ -9203,7 +9361,21 @@ allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int size
 
 	buf->tr = tr;
 
-	buf->buffer = ring_buffer_alloc(size, rb_flags);
+	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);
+
+		ring_buffer_last_boot_delta(buf->buffer,
+					    &tr->text_delta, &tr->data_delta);
+		/*
+		 * 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;
 
@@ -9240,6 +9412,10 @@ 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")) {
@@ -9340,7 +9516,9 @@ 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;
@@ -9366,6 +9544,10 @@ 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);
@@ -9423,7 +9605,7 @@ 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)
@@ -9448,6 +9630,31 @@ out_unlock:
 	return ret;
 }
 
+static u64 map_pages(u64 start, u64 size)
+{
+	struct page **pages;
+	phys_addr_t page_start;
+	unsigned int page_count;
+	unsigned int i;
+	void *vaddr;
+
+	page_count = DIV_ROUND_UP(size, PAGE_SIZE);
+
+	page_start = start;
+	pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
+	if (!pages)
+		return 0;
+
+	for (i = 0; i < page_count; i++) {
+		phys_addr_t addr = page_start + i * PAGE_SIZE;
+		pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
+	}
+	vaddr = vmap(pages, page_count, VM_MAP, PAGE_KERNEL);
+	kfree(pages);
+
+	return (u64)(unsigned long)vaddr;
+}
+
 /**
  * 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.
@@ -9477,7 +9684,7 @@ 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;
@@ -9507,6 +9714,9 @@ static int __remove_instance(struct trace_array *tr)
 			set_tracer_flag(tr, 1 << i, 0);
 	}
 
+	if (printk_trace == tr)
+		update_printk_trace(&global_trace);
+
 	tracing_set_nop(tr);
 	clear_ftrace_function_probes(tr);
 	event_trace_del_tracer(tr);
@@ -9669,10 +9879,15 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 	if (ftrace_create_function_files(tr, d_tracer))
 		MEM_FAIL(1, "Could not allocate function filter files");
 
+	if (tr->range_addr_start) {
+		trace_create_file("last_boot_info", TRACE_MODE_READ, d_tracer,
+				  tr, &last_boot_fops);
 #ifdef CONFIG_TRACER_SNAPSHOT
-	trace_create_file("snapshot", TRACE_MODE_WRITE, d_tracer,
-			  tr, &snapshot_fops);
+	} else {
+		trace_create_file("snapshot", TRACE_MODE_WRITE, d_tracer,
+				  tr, &snapshot_fops);
 #endif
+	}
 
 	trace_create_file("error_log", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_err_log_fops);
@@ -10292,6 +10507,7 @@ __init static void enable_instances(void)
 {
 	struct trace_array *tr;
 	char *curr_str;
+	char *name;
 	char *str;
 	char *tok;
 
@@ -10300,19 +10516,107 @@ __init static void enable_instances(void)
 	str = boot_instance_info;
 
 	while ((curr_str = strsep(&str, "\t"))) {
+		phys_addr_t start = 0;
+		phys_addr_t size = 0;
+		unsigned long addr = 0;
+		bool traceprintk = false;
+		bool traceoff = false;
+		char *flag_delim;
+		char *addr_delim;
 
 		tok = strsep(&curr_str, ",");
 
-		if (IS_ENABLED(CONFIG_TRACER_MAX_TRACE))
-			do_allocate_snapshot(tok);
+		flag_delim = strchr(tok, '^');
+		addr_delim = strchr(tok, '@');
 
-		tr = trace_array_get_by_name(tok, NULL);
-		if (!tr) {
-			pr_warn("Failed to create instance buffer %s\n", curr_str);
+		if (addr_delim)
+			*addr_delim++ = '\0';
+
+		if (flag_delim)
+			*flag_delim++ = '\0';
+
+		name = tok;
+
+		if (flag_delim) {
+			char *flag;
+
+			while ((flag = strsep(&flag_delim, "^"))) {
+				if (strcmp(flag, "traceoff") == 0) {
+					traceoff = true;
+				} else if ((strcmp(flag, "printk") == 0) ||
+					   (strcmp(flag, "traceprintk") == 0) ||
+					   (strcmp(flag, "trace_printk") == 0)) {
+					traceprintk = true;
+				} else {
+					pr_info("Tracing: Invalid instance flag '%s' for %s\n",
+						flag, name);
+				}
+			}
+		}
+
+		tok = addr_delim;
+		if (tok && isdigit(*tok)) {
+			start = memparse(tok, &tok);
+			if (!start) {
+				pr_warn("Tracing: Invalid boot instance address for %s\n",
+					name);
+				continue;
+			}
+			if (*tok != ':') {
+				pr_warn("Tracing: No size specified for instance %s\n", name);
+				continue;
+			}
+			tok++;
+			size = memparse(tok, &tok);
+			if (!size) {
+				pr_warn("Tracing: Invalid boot instance size for %s\n",
+					name);
+				continue;
+			}
+		} else if (tok) {
+			if (!reserve_mem_find_by_name(tok, &start, &size)) {
+				start = 0;
+				pr_warn("Failed to map boot instance %s to %s\n", name, tok);
+				continue;
+			}
+		}
+
+		if (start) {
+			addr = map_pages(start, size);
+			if (addr) {
+				pr_info("Tracing: mapped boot instance %s at physical memory %pa of size 0x%lx\n",
+					name, &start, (unsigned long)size);
+			} else {
+				pr_warn("Tracing: Failed to map boot instance %s\n", name);
+				continue;
+			}
+		} else {
+			/* Only non mapped buffers have snapshot buffers */
+			if (IS_ENABLED(CONFIG_TRACER_MAX_TRACE))
+				do_allocate_snapshot(name);
+		}
+
+		tr = trace_array_create_systems(name, NULL, addr, size);
+		if (IS_ERR(tr)) {
+			pr_warn("Tracing: Failed to create instance buffer %s\n", curr_str);
 			continue;
 		}
-		/* Allow user space to delete it */
-		trace_array_put(tr);
+
+		if (traceoff)
+			tracer_tracing_off(tr);
+
+		if (traceprintk)
+			update_printk_trace(tr);
+
+		/*
+		 * If start is set, then this is a mapped buffer, and
+		 * cannot be deleted by user space, so keep the reference
+		 * to it.
+		 */
+		if (start)
+			tr->flags |= TRACE_ARRAY_FL_BOOT;
+		else
+			trace_array_put(tr);
 
 		while ((tok = strsep(&curr_str, ","))) {
 			early_enable_events(tr, tok, true);