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[PATCH] usb: gadget: functions: add ftrace export over USB

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  [PATCH] usb: gadget: functions: add ftrace export over USB Felipe Balbi <felipe.balbi@linux.intel.com> - 2017-06-09 08:20 +0200
    Re: [PATCH] usb: gadget: functions: add ftrace export over USB Felipe Balbi <felipe.balbi@linux.intel.com> - 2017-06-09 12:30 +0200
      Re: [PATCH] usb: gadget: functions: add ftrace export over USB Felipe Balbi <felipe.balbi@linux.intel.com> - 2017-06-09 13:20 +0200
    Re: [PATCH] usb: gadget: functions: add ftrace export over USB Steven Rostedt <rostedt@goodmis.org> - 2017-06-09 16:10 +0200
      Re: [PATCH] usb: gadget: functions: add ftrace export over USB Felipe Balbi <felipe.balbi@linux.intel.com> - 2017-06-09 16:10 +0200
        Re: [PATCH] usb: gadget: functions: add ftrace export over USB Steven Rostedt <rostedt@goodmis.org> - 2017-06-09 17:10 +0200

#1661951 — [PATCH] usb: gadget: functions: add ftrace export over USB

Allow for ftrace data to be exported over a USB Gadget
Controller. With this, we have a potentially very fast pipe for
transmitting ftrace data to a Host PC for further analysis.

Note that in order to decode the data, one needs access to kernel
symbols in order to convert binary data into function names and what
not.

Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
---

I wanted to take this through the gadget tree, but there is a
dependency with a previous patch of mine adding and extra argument to
the ->write() function. Hoping someone else will take it.

 drivers/usb/gadget/Kconfig            |  15 ++
 drivers/usb/gadget/function/Makefile  |   2 +
 drivers/usb/gadget/function/f-trace.c | 400 ++++++++++++++++++++++++++++++++++
 3 files changed, 417 insertions(+)
 create mode 100644 drivers/usb/gadget/function/f-trace.c

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index c164d6b788c3..617921f19b5e 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -188,6 +188,9 @@ config USB_F_MASS_STORAGE
 config USB_F_FS
 	tristate
 
+config USB_F_TRACE
+	tristate
+
 config USB_F_UAC1
 	tristate
 
@@ -362,6 +365,18 @@ config USB_CONFIGFS_F_FS
 	  implemented in kernel space (for instance Ethernet, serial or
 	  mass storage) and other are implemented in user space.
 
+config USB_CONFIGFS_F_TRACE
+	bool "Linux FTrace Export Over USB"
+	depends on USB_CONFIGFS
+	select USB_F_TRACE
+	help
+	  The Linux FTrace Export Over USB lets one export ftrace buffer
+	  over a USB cable to a host computer for further processing.
+
+	  If you want support for that, say Y or M here. Otherwise say N.
+
+	  If unsure, say N.
+
 config USB_CONFIGFS_F_UAC1
 	bool "Audio Class 1.0"
 	depends on USB_CONFIGFS
diff --git a/drivers/usb/gadget/function/Makefile b/drivers/usb/gadget/function/Makefile
index cb8c225e8549..1433e8ad7675 100644
--- a/drivers/usb/gadget/function/Makefile
+++ b/drivers/usb/gadget/function/Makefile
@@ -46,3 +46,5 @@ usb_f_printer-y			:= f_printer.o
 obj-$(CONFIG_USB_F_PRINTER)	+= usb_f_printer.o
 usb_f_tcm-y			:= f_tcm.o
 obj-$(CONFIG_USB_F_TCM)		+= usb_f_tcm.o
+usb_f_trace-y			:= f-trace.o
+obj-$(CONFIG_USB_F_TRACE)	+= usb_f_trace.o
diff --git a/drivers/usb/gadget/function/f-trace.c b/drivers/usb/gadget/function/f-trace.c
new file mode 100644
index 000000000000..7de92950c0e7
--- /dev/null
+++ b/drivers/usb/gadget/function/f-trace.c
@@ -0,0 +1,400 @@
+/*
+ * f_trace.c -- USB FTrace Export
+ *
+ * Copyright (C) 2017 Intel Corporation
+ * Author: Felipe Balbi <felipe.balbi@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License v2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/trace.h>
+#include <linux/usb.h>
+#include <linux/usb/composite.h>
+#include <linux/usb/gadget.h>
+#include <linux/workqueue.h>
+
+struct usb_ftrace {
+	struct trace_export ftrace;
+	struct usb_function function;
+	struct work_struct queue_work;
+	spinlock_t lock;
+
+	struct list_head list;
+	struct list_head pending;
+	struct list_head queued;
+
+	struct usb_ep *in;
+
+	u8 intf_id;
+};
+#define ftrace_to_trace(f)	(container_of((f), struct usb_ftrace, ftrace))
+#define work_to_trace(w)	(container_of((w), struct usb_ftrace, queue_work))
+#define to_trace(f)		(container_of((f), struct usb_ftrace, function))
+
+#define FTRACE_REQUEST_QUEUE_LENGTH	250
+
+static inline struct usb_request *next_request(struct list_head *list)
+{
+	return list_first_entry_or_null(list, struct usb_request, list);
+}
+
+struct usb_ftrace_opts {
+	struct usb_function_instance func_inst;
+};
+#define to_opts(fi)	(container_of((fi), struct usb_ftrace_opts, func_inst))
+
+static struct usb_interface_descriptor ftrace_intf_desc = {
+	.bLength		= USB_DT_INTERFACE_SIZE,
+	.bDescriptorType	= USB_DT_INTERFACE,
+
+	.bAlternateSetting	= 0,
+	.bNumEndpoints		= 1,
+	.bInterfaceClass	= USB_CLASS_VENDOR_SPEC,
+	.bInterfaceSubClass	= USB_SUBCLASS_VENDOR_SPEC,
+};
+
+/* Super-Speed Support */
+static struct usb_endpoint_descriptor ftrace_ss_in_desc = {
+	.bLength		= USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType	= USB_DT_ENDPOINT,
+
+	.bEndpointAddress	= USB_DIR_IN,
+	.bmAttributes		= USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize		= cpu_to_le16(1024),
+};
+
+static struct usb_ss_ep_comp_descriptor ftrace_ss_in_comp_desc = {
+	.bLength		= USB_DT_SS_EP_COMP_SIZE,
+	.bDescriptorType	= USB_DT_SS_ENDPOINT_COMP,
+
+	.bMaxBurst		= 15,
+};
+
+static struct usb_descriptor_header *ftrace_ss_function[] = {
+	(struct usb_descriptor_header *) &ftrace_intf_desc,
+	(struct usb_descriptor_header *) &ftrace_ss_in_desc,
+	(struct usb_descriptor_header *) &ftrace_ss_in_comp_desc,
+	NULL,
+};
+
+/* High-Speed Support */
+static struct usb_endpoint_descriptor ftrace_hs_in_desc = {
+	.bLength		= USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType	= USB_DT_ENDPOINT,
+
+	.bEndpointAddress	= USB_DIR_IN,
+	.bmAttributes		= USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize		= cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *ftrace_hs_function[] = {
+	(struct usb_descriptor_header *) &ftrace_intf_desc,
+	(struct usb_descriptor_header *) &ftrace_hs_in_desc,
+	NULL,
+};
+
+/* Full-Speed Support */
+static struct usb_endpoint_descriptor ftrace_fs_in_desc = {
+	.bLength		= USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType	= USB_DT_ENDPOINT,
+
+	.bEndpointAddress	= USB_DIR_IN,
+	.bmAttributes		= USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize		= cpu_to_le16(64),
+};
+
+static struct usb_descriptor_header *ftrace_fs_function[] = {
+	(struct usb_descriptor_header *) &ftrace_intf_desc,
+	(struct usb_descriptor_header *) &ftrace_fs_in_desc,
+	NULL,
+};
+
+static struct usb_string ftrace_string_defs[] = {
+	[0].s = "Linux Ftrace Export",
+	{ },
+};
+
+static struct usb_gadget_strings ftrace_string_table = {
+	.language		= 0x0409, /* en-US */
+	.strings		= ftrace_string_defs,
+};
+
+static struct usb_gadget_strings *ftrace_strings[] = {
+	&ftrace_string_table,
+	NULL,
+};
+
+/* ------------------------------------------------------------------------ */
+
+static void ftrace_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct usb_ftrace		*trace = req->context;
+
+	kfree(req->buf);
+	list_move_tail(&req->list, &trace->list);
+}
+
+static void ftrace_queue_work(struct work_struct *work)
+{
+	struct usb_ftrace		*trace = work_to_trace(work);
+	struct usb_request		*req;
+	struct usb_request		*tmp;
+	struct list_head		local_list;
+
+	spin_lock_irq(&trace->lock);
+restart:
+	list_replace_init(&trace->pending, &local_list);
+	spin_unlock_irq(&trace->lock);
+
+	list_for_each_entry_safe(req, tmp, &local_list, list) {
+		int			ret;
+
+		ret = usb_ep_queue(trace->in, req, GFP_KERNEL);
+		if (!ret)
+			list_move_tail(&req->list, &trace->queued);
+	}
+
+	spin_lock_irq(&trace->lock);
+	if (!list_empty(&trace->pending))
+		goto restart;
+	spin_unlock_irq(&trace->lock);
+}
+
+static void notrace ftrace_write(struct trace_export *ftrace, const void *buf,
+				 unsigned int len)
+{
+	struct usb_ftrace		*trace = ftrace_to_trace(ftrace);
+	struct usb_request		*req = next_request(&trace->list);
+
+	if (!req)
+		return;
+
+	if (!trace->in->enabled)
+		return;
+
+	req->buf = kmemdup(buf, len, GFP_ATOMIC);
+	req->length = len;
+	req->context = trace;
+	req->complete = ftrace_complete;
+	list_move_tail(&req->list, &trace->pending);
+
+	schedule_work(&trace->queue_work);
+}
+
+/* ------------------------------------------------------------------------ */
+
+static void ftrace_disable_endpoint(struct usb_ftrace *trace)
+{
+	if (trace->in->enabled)
+		WARN_ON(usb_ep_disable(trace->in));
+}
+
+static int ftrace_enable_endpoint(struct usb_ftrace *trace)
+{
+	if (trace->in->enabled)
+		return 0;
+
+	return usb_ep_enable(trace->in);
+}
+
+static int ftrace_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+	struct usb_ftrace		*trace = to_trace(f);
+	struct usb_composite_dev	*cdev = f->config->cdev;
+	int				ret;
+
+	if (alt != 0)
+		goto fail;
+
+	if (intf != trace->intf_id)
+		goto fail;
+
+	ftrace_disable_endpoint(trace);
+
+	if (!trace->in->desc) {
+		ret = config_ep_by_speed(cdev->gadget, f, trace->in);
+		if (ret) {
+			trace->in->desc = NULL;
+			goto fail;
+		}
+	}
+
+	ret = ftrace_enable_endpoint(trace);
+	if (ret)
+		goto fail;
+
+	return 0;
+
+fail:
+	return -EINVAL;
+}
+
+static int ftrace_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev	*cdev = c->cdev;
+	struct usb_ftrace		*trace = to_trace(f);
+	struct usb_string		*us;
+	struct usb_ep			*ep;
+
+	int				ret;
+	int				i;
+
+	us = usb_gstrings_attach(cdev, ftrace_strings,
+				 ARRAY_SIZE(ftrace_string_defs));
+	if (IS_ERR(us))
+		return PTR_ERR(us);
+
+	ftrace_intf_desc.iInterface = us[0].id;
+
+	ret = usb_interface_id(c, f);
+	if (ret < 0)
+		goto err0;
+	trace->intf_id = ret;
+	ftrace_intf_desc.bInterfaceNumber = ret;
+
+	ep = usb_ep_autoconfig(cdev->gadget, &ftrace_fs_in_desc);
+	if (!ep)
+		goto err0;
+	trace->in = ep;
+
+	ftrace_hs_in_desc.bEndpointAddress = ftrace_fs_in_desc.bEndpointAddress;
+	ftrace_ss_in_desc.bEndpointAddress = ftrace_fs_in_desc.bEndpointAddress;
+
+	trace->ftrace.write = ftrace_write;
+
+	spin_lock_init(&trace->lock);
+	INIT_WORK(&trace->queue_work, ftrace_queue_work);
+	INIT_LIST_HEAD(&trace->list);
+	INIT_LIST_HEAD(&trace->pending);
+	INIT_LIST_HEAD(&trace->queued);
+
+	ret = usb_assign_descriptors(f, ftrace_fs_function, ftrace_hs_function,
+				     ftrace_ss_function, NULL);
+	if (ret)
+		goto err0;
+
+	for (i = 0; i < FTRACE_REQUEST_QUEUE_LENGTH; i++) {
+		struct usb_request *req;
+
+		req = usb_ep_alloc_request(trace->in, GFP_KERNEL);
+		if (!req)
+			goto err1;
+
+		list_add_tail(&req->list, &trace->list);
+	}
+
+	ret = register_ftrace_export(&trace->ftrace);
+	if (ret)
+		goto err1;
+
+	return 0;
+
+err1:
+	while (!list_empty(&trace->list)) {
+		struct usb_request *req = next_request(&trace->list);
+
+		usb_ep_free_request(trace->in, req);
+		list_del(&req->list);
+	}
+
+	usb_free_all_descriptors(f);
+
+err0:
+	ERROR(cdev, "%s: can't bind --> err %d\n", f->name, ret);
+
+	return ret;
+}
+
+static void ftrace_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_ftrace		*trace = to_trace(f);
+	struct usb_request		*req;
+	struct usb_request		*tmp;
+
+	unregister_ftrace_export(&trace->ftrace);
+	cancel_work_sync(&trace->queue_work);
+	usb_free_all_descriptors(f);
+
+	list_for_each_entry(req, &trace->queued, list)
+		usb_ep_dequeue(trace->in, req);
+
+	list_for_each_entry_safe(req, tmp, &trace->pending, list) {
+		usb_ep_free_request(trace->in, req);
+		list_del(&req->list);
+	}
+
+	list_for_each_entry_safe(req, tmp, &trace->list, list) {
+		usb_ep_free_request(trace->in, req);
+		list_del(&req->list);
+	}
+}
+
+static void ftrace_disable(struct usb_function *f)
+{
+	struct usb_ftrace		*trace = to_trace(f);
+
+	ftrace_disable_endpoint(trace);
+}
+
+static void ftrace_free_func(struct usb_function *f)
+{
+	kfree(to_trace(f));
+}
+
+static struct config_item_type ftrace_func_type = {
+	.ct_owner		= THIS_MODULE,
+};
+
+static void ftrace_free_inst(struct usb_function_instance *fi)
+{
+	struct usb_ftrace_opts		*opts = to_opts(fi);
+
+	kfree(opts);
+}
+
+static struct usb_function_instance *ftrace_alloc_inst(void)
+{
+	struct usb_ftrace_opts		*opts;
+
+	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+	if (!opts)
+		return ERR_PTR(-ENOMEM);
+
+	opts->func_inst.free_func_inst = ftrace_free_inst;
+
+	config_group_init_type_name(&opts->func_inst.group, "",
+				    &ftrace_func_type);
+
+	return &opts->func_inst;
+}
+
+static struct usb_function *ftrace_alloc(struct usb_function_instance *fi)
+{
+	struct usb_ftrace		*trace;
+
+	trace = kzalloc(sizeof(*trace), GFP_KERNEL);
+	if (!trace)
+		return NULL;
+
+	trace->function.name = "ftrace";
+	trace->function.bind = ftrace_bind;
+	trace->function.unbind = ftrace_unbind;
+	trace->function.set_alt = ftrace_set_alt;
+	trace->function.disable = ftrace_disable;
+	trace->function.strings = ftrace_strings;
+	trace->function.free_func = ftrace_free_func;
+
+	return &trace->function;
+}
+
+DECLARE_USB_FUNCTION_INIT(ftrace, ftrace_alloc_inst, ftrace_alloc);
+MODULE_AUTHOR("Felipe Balbi <felipe.balbi@linux.intel.com>");
+MODULE_LICENSE("GPL v2");
-- 
2.11.0.295.gd7dffce1ce

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#1662261

[Multipart message — attachments visible in raw view] — view raw

Felipe Balbi <felipe.balbi@linux.intel.com> writes:

> Allow for ftrace data to be exported over a USB Gadget
> Controller. With this, we have a potentially very fast pipe for
> transmitting ftrace data to a Host PC for further analysis.
>
> Note that in order to decode the data, one needs access to kernel
> symbols in order to convert binary data into function names and what
> not.
>
> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
> ---
>
> I wanted to take this through the gadget tree, but there is a
> dependency with a previous patch of mine adding and extra argument to
> the ->write() function. Hoping someone else will take it.

just as an extra note here. In order for this to be really useful, it
would be nice to be able to control what is going to be traced over USB
as well, but that means exporting a few extra functions to GPL drivers.

Would that be okay? I could have a set of vendor-specific control
requests to set buffer size and to read/write ftrace filter functions.

The idea is that things like e.g. Android SDK could rely on this on
debug builds and the SDK itself would make sure to keep a copy of
vmlinux around to processing of the data coming through USB.

-- 
balbi

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#1662310

[Multipart message — attachments visible in raw view] — view raw

Felipe Balbi <felipe.balbi@linux.intel.com> writes:

> Felipe Balbi <felipe.balbi@linux.intel.com> writes:
>
>> Allow for ftrace data to be exported over a USB Gadget
>> Controller. With this, we have a potentially very fast pipe for
>> transmitting ftrace data to a Host PC for further analysis.
>>
>> Note that in order to decode the data, one needs access to kernel
>> symbols in order to convert binary data into function names and what
>> not.
>>
>> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
>> ---
>>
>> I wanted to take this through the gadget tree, but there is a
>> dependency with a previous patch of mine adding and extra argument to
>> the ->write() function. Hoping someone else will take it.
>
> just as an extra note here. In order for this to be really useful, it
> would be nice to be able to control what is going to be traced over USB
> as well, but that means exporting a few extra functions to GPL drivers.
>
> Would that be okay? I could have a set of vendor-specific control
> requests to set buffer size and to read/write ftrace filter functions.
>
> The idea is that things like e.g. Android SDK could rely on this on
> debug builds and the SDK itself would make sure to keep a copy of
> vmlinux around to processing of the data coming through USB.

something along these lines (although I think trace buffer size doesn't
matter for trace export, but it serves well enough to illustrate a
point):

modified   drivers/usb/gadget/function/f-trace.c
@@ -33,6 +33,8 @@ struct usb_ftrace {
 
 	struct usb_ep *in;
 
+	u32 buffer_size;
+	u16 version;
 	u8 intf_id;
 };
 #define ftrace_to_trace(f)	(container_of((f), struct usb_ftrace, ftrace))
@@ -40,6 +42,12 @@ struct usb_ftrace {
 #define to_trace(f)		(container_of((f), struct usb_ftrace, function))
 
 #define FTRACE_REQUEST_QUEUE_LENGTH	250
+#define FTRACE_VERSION			0x0100 /* bcd 1.00 */
+
+/* FTrace vendor-specific requests */
+#define USB_FTRACE_GET_VERSION		0x00
+#define USB_FTRACE_GET_TRACE_BUF_SIZE	0x01
+#define USB_FTRACE_SET_TRACE_BUF_SIZE	0x02
 
 static inline struct usb_request *next_request(struct list_head *list)
 {
@@ -142,6 +150,13 @@ static void ftrace_complete(struct usb_ep *ep, struct usb_request *req)
 	list_move_tail(&req->list, &trace->list);
 }
 
+static void ftrace_set_trace_buf_size_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct usb_ftrace		*trace = req->context;
+
+	trace_set_buf_size(le32_to_cpu(trace->buffer_size));
+}
+
 static void ftrace_queue_work(struct work_struct *work)
 {
 	struct usb_ftrace		*trace = work_to_trace(work);
@@ -237,6 +252,71 @@ static int ftrace_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 	return -EINVAL;
 }
 
+extern unsigned long trace_get_buf_size(void);
+
+static int ftrace_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+	struct usb_configuration	*c = f->config;
+	struct usb_request		*req = c->cdev->req;
+	struct usb_ftrace		*trace = to_trace(f);
+
+	int				ret;
+
+	u16				index = le16_to_cpu(ctrl->wIndex);
+	u16				value = le16_to_cpu(ctrl->wValue);
+	u16				length = le16_to_cpu(ctrl->wLength);
+
+	if (value != 0 || index != 0)
+		return -EINVAL;
+
+	switch (ctrl->bRequest) {
+	case USB_FTRACE_GET_VERSION:
+		if (ctrl->bRequestType != (USB_DIR_IN | USB_TYPE_VENDOR |
+					   USB_RECIP_INTERFACE))
+			return -EINVAL;
+
+		if (length != 2)
+			return -EINVAL;
+
+		req->zero = 0;
+		req->length = 2;
+		req->buf = &trace->version;
+		break;
+	case USB_FTRACE_GET_TRACE_BUF_SIZE:
+		if (ctrl->bRequestType != (USB_DIR_IN | USB_TYPE_VENDOR |
+					   USB_RECIP_INTERFACE))
+			return -EINVAL;
+
+		if (length != 2)
+			return -EINVAL;
+
+		trace->buffer_size = cpu_to_le32(trace_get_buf_size());
+
+		req->zero = 0;
+		req->length = 2;
+		req->buf = &trace->buffer_size;
+		break;
+	case USB_FTRACE_SET_TRACE_BUF_SIZE:
+		if (ctrl->bRequestType != (USB_DIR_OUT | USB_TYPE_VENDOR |
+					   USB_RECIP_INTERFACE))
+			return -EINVAL;
+
+		if (length != 4)
+			return -EINVAL;
+
+		req->zero = 0;
+		req->length = 4;
+		req->context = trace;
+		req->complete = ftrace_set_trace_buf_size_complete;
+		req->buf = &trace->buffer_size;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return usb_ep_queue(c->cdev->gadget->ep0, req, GFP_ATOMIC);
+}
+
 static int ftrace_bind(struct usb_configuration *c, struct usb_function *f)
 {
 	struct usb_composite_dev	*cdev = c->cdev;
@@ -247,6 +327,8 @@ static int ftrace_bind(struct usb_configuration *c, struct usb_function *f)
 	int				ret;
 	int				i;
 
+	trace->version = cpu_to_le16(FTRACE_VERSION);
+
 	us = usb_gstrings_attach(cdev, ftrace_strings,
 				 ARRAY_SIZE(ftrace_string_defs));
 	if (IS_ERR(us))
modified   kernel/trace/trace.c
@@ -618,6 +618,12 @@ int tracing_is_enabled(void)
 
 static unsigned long		trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
 
+unsigned long trace_get_buf_size(void)
+{
+	return trace_buf_size;
+}
+EXPORT_SYMBOL_GPL(trace_get_buf_size);
+
 /* trace_types holds a link list of available tracers. */
 static struct tracer		*trace_types __read_mostly;
 

-- 
balbi

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#1662481

On Fri,  9 Jun 2017 09:13:27 +0300
Felipe Balbi <felipe.balbi@linux.intel.com> wrote:

> Allow for ftrace data to be exported over a USB Gadget
> Controller. With this, we have a potentially very fast pipe for
> transmitting ftrace data to a Host PC for further analysis.
> 
> Note that in order to decode the data, one needs access to kernel
> symbols in order to convert binary data into function names and what
> not.
> 

Can you please explain what this is in a bit more detail. I have no
idea what you are trying to accomplish.

Also, do you mean ftrace as the internal Linux tracer (which should
only be called "ftrace" or sometimes "Ftrace" but not "f_trace" or
"FTrace", that just leads to more confusion.

Or is this to do with http://www.ftrace.com/en/gb, a way to trace
produce ;-)

-- Steve


> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
> ---
> 
> I wanted to take this through the gadget tree, but there is a
> dependency with a previous patch of mine adding and extra argument to
> the ->write() function. Hoping someone else will take it.
> 
>  drivers/usb/gadget/Kconfig            |  15 ++
>  drivers/usb/gadget/function/Makefile  |   2 +
>  drivers/usb/gadget/function/f-trace.c | 400 ++++++++++++++++++++++++++++++++++
>  3 files changed, 417 insertions(+)
>  create mode 100644 drivers/usb/gadget/function/f-trace.c
> 
> diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
> index c164d6b788c3..617921f19b5e 100644
> --- a/drivers/usb/gadget/Kconfig
> +++ b/drivers/usb/gadget/Kconfig
> @@ -188,6 +188,9 @@ config USB_F_MASS_STORAGE
>  config USB_F_FS
>  	tristate
>  
> +config USB_F_TRACE
> +	tristate
> +
>  config USB_F_UAC1
>  	tristate
>  
> @@ -362,6 +365,18 @@ config USB_CONFIGFS_F_FS
>  	  implemented in kernel space (for instance Ethernet, serial or
>  	  mass storage) and other are implemented in user space.
>  
> +config USB_CONFIGFS_F_TRACE
> +	bool "Linux FTrace Export Over USB"
> +	depends on USB_CONFIGFS
> +	select USB_F_TRACE
> +	help
> +	  The Linux FTrace Export Over USB lets one export ftrace buffer
> +	  over a USB cable to a host computer for further processing.
> +
> +	  If you want support for that, say Y or M here. Otherwise say N.
> +
> +	  If unsure, say N.
> +
>  config USB_CONFIGFS_F_UAC1
>  	bool "Audio Class 1.0"
>  	depends on USB_CONFIGFS
> diff --git a/drivers/usb/gadget/function/Makefile b/drivers/usb/gadget/function/Makefile
> index cb8c225e8549..1433e8ad7675 100644
> --- a/drivers/usb/gadget/function/Makefile
> +++ b/drivers/usb/gadget/function/Makefile
> @@ -46,3 +46,5 @@ usb_f_printer-y			:= f_printer.o
>  obj-$(CONFIG_USB_F_PRINTER)	+= usb_f_printer.o
>  usb_f_tcm-y			:= f_tcm.o
>  obj-$(CONFIG_USB_F_TCM)		+= usb_f_tcm.o
> +usb_f_trace-y			:= f-trace.o
> +obj-$(CONFIG_USB_F_TRACE)	+= usb_f_trace.o
> diff --git a/drivers/usb/gadget/function/f-trace.c b/drivers/usb/gadget/function/f-trace.c
> new file mode 100644
> index 000000000000..7de92950c0e7
> --- /dev/null
> +++ b/drivers/usb/gadget/function/f-trace.c
> @@ -0,0 +1,400 @@
> +/*
> + * f_trace.c -- USB FTrace Export
> + *
> + * Copyright (C) 2017 Intel Corporation
> + * Author: Felipe Balbi <felipe.balbi@linux.intel.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License v2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/list.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +#include <linux/trace.h>
> +#include <linux/usb.h>
> +#include <linux/usb/composite.h>
> +#include <linux/usb/gadget.h>
> +#include <linux/workqueue.h>
> +
> +struct usb_ftrace {
> +	struct trace_export ftrace;
> +	struct usb_function function;
> +	struct work_struct queue_work;
> +	spinlock_t lock;
> +
> +	struct list_head list;
> +	struct list_head pending;
> +	struct list_head queued;
> +
> +	struct usb_ep *in;
> +
> +	u8 intf_id;
> +};
> +#define ftrace_to_trace(f)	(container_of((f), struct usb_ftrace, ftrace))
> +#define work_to_trace(w)	(container_of((w), struct usb_ftrace, queue_work))
> +#define to_trace(f)		(container_of((f), struct usb_ftrace, function))
> +
> +#define FTRACE_REQUEST_QUEUE_LENGTH	250
> +
> +static inline struct usb_request *next_request(struct list_head *list)
> +{
> +	return list_first_entry_or_null(list, struct usb_request, list);
> +}
> +
> +struct usb_ftrace_opts {
> +	struct usb_function_instance func_inst;
> +};
> +#define to_opts(fi)	(container_of((fi), struct usb_ftrace_opts, func_inst))
> +
> +static struct usb_interface_descriptor ftrace_intf_desc = {
> +	.bLength		= USB_DT_INTERFACE_SIZE,
> +	.bDescriptorType	= USB_DT_INTERFACE,
> +
> +	.bAlternateSetting	= 0,
> +	.bNumEndpoints		= 1,
> +	.bInterfaceClass	= USB_CLASS_VENDOR_SPEC,
> +	.bInterfaceSubClass	= USB_SUBCLASS_VENDOR_SPEC,
> +};
> +
> +/* Super-Speed Support */
> +static struct usb_endpoint_descriptor ftrace_ss_in_desc = {
> +	.bLength		= USB_DT_ENDPOINT_SIZE,
> +	.bDescriptorType	= USB_DT_ENDPOINT,
> +
> +	.bEndpointAddress	= USB_DIR_IN,
> +	.bmAttributes		= USB_ENDPOINT_XFER_BULK,
> +	.wMaxPacketSize		= cpu_to_le16(1024),
> +};
> +
> +static struct usb_ss_ep_comp_descriptor ftrace_ss_in_comp_desc = {
> +	.bLength		= USB_DT_SS_EP_COMP_SIZE,
> +	.bDescriptorType	= USB_DT_SS_ENDPOINT_COMP,
> +
> +	.bMaxBurst		= 15,
> +};
> +
> +static struct usb_descriptor_header *ftrace_ss_function[] = {
> +	(struct usb_descriptor_header *) &ftrace_intf_desc,
> +	(struct usb_descriptor_header *) &ftrace_ss_in_desc,
> +	(struct usb_descriptor_header *) &ftrace_ss_in_comp_desc,
> +	NULL,
> +};
> +
> +/* High-Speed Support */
> +static struct usb_endpoint_descriptor ftrace_hs_in_desc = {
> +	.bLength		= USB_DT_ENDPOINT_SIZE,
> +	.bDescriptorType	= USB_DT_ENDPOINT,
> +
> +	.bEndpointAddress	= USB_DIR_IN,
> +	.bmAttributes		= USB_ENDPOINT_XFER_BULK,
> +	.wMaxPacketSize		= cpu_to_le16(512),
> +};
> +
> +static struct usb_descriptor_header *ftrace_hs_function[] = {
> +	(struct usb_descriptor_header *) &ftrace_intf_desc,
> +	(struct usb_descriptor_header *) &ftrace_hs_in_desc,
> +	NULL,
> +};
> +
> +/* Full-Speed Support */
> +static struct usb_endpoint_descriptor ftrace_fs_in_desc = {
> +	.bLength		= USB_DT_ENDPOINT_SIZE,
> +	.bDescriptorType	= USB_DT_ENDPOINT,
> +
> +	.bEndpointAddress	= USB_DIR_IN,
> +	.bmAttributes		= USB_ENDPOINT_XFER_BULK,
> +	.wMaxPacketSize		= cpu_to_le16(64),
> +};
> +
> +static struct usb_descriptor_header *ftrace_fs_function[] = {
> +	(struct usb_descriptor_header *) &ftrace_intf_desc,
> +	(struct usb_descriptor_header *) &ftrace_fs_in_desc,
> +	NULL,
> +};
> +
> +static struct usb_string ftrace_string_defs[] = {
> +	[0].s = "Linux Ftrace Export",
> +	{ },
> +};
> +
> +static struct usb_gadget_strings ftrace_string_table = {
> +	.language		= 0x0409, /* en-US */
> +	.strings		= ftrace_string_defs,
> +};
> +
> +static struct usb_gadget_strings *ftrace_strings[] = {
> +	&ftrace_string_table,
> +	NULL,
> +};
> +
> +/* ------------------------------------------------------------------------ */
> +
> +static void ftrace_complete(struct usb_ep *ep, struct usb_request *req)
> +{
> +	struct usb_ftrace		*trace = req->context;
> +
> +	kfree(req->buf);
> +	list_move_tail(&req->list, &trace->list);
> +}
> +
> +static void ftrace_queue_work(struct work_struct *work)
> +{
> +	struct usb_ftrace		*trace = work_to_trace(work);
> +	struct usb_request		*req;
> +	struct usb_request		*tmp;
> +	struct list_head		local_list;
> +
> +	spin_lock_irq(&trace->lock);
> +restart:
> +	list_replace_init(&trace->pending, &local_list);
> +	spin_unlock_irq(&trace->lock);
> +
> +	list_for_each_entry_safe(req, tmp, &local_list, list) {
> +		int			ret;
> +
> +		ret = usb_ep_queue(trace->in, req, GFP_KERNEL);
> +		if (!ret)
> +			list_move_tail(&req->list, &trace->queued);
> +	}
> +
> +	spin_lock_irq(&trace->lock);
> +	if (!list_empty(&trace->pending))
> +		goto restart;
> +	spin_unlock_irq(&trace->lock);
> +}
> +
> +static void notrace ftrace_write(struct trace_export *ftrace, const void *buf,
> +				 unsigned int len)
> +{
> +	struct usb_ftrace		*trace = ftrace_to_trace(ftrace);
> +	struct usb_request		*req = next_request(&trace->list);
> +
> +	if (!req)
> +		return;
> +
> +	if (!trace->in->enabled)
> +		return;
> +
> +	req->buf = kmemdup(buf, len, GFP_ATOMIC);
> +	req->length = len;
> +	req->context = trace;
> +	req->complete = ftrace_complete;
> +	list_move_tail(&req->list, &trace->pending);
> +
> +	schedule_work(&trace->queue_work);
> +}
> +
> +/* ------------------------------------------------------------------------ */
> +
> +static void ftrace_disable_endpoint(struct usb_ftrace *trace)
> +{
> +	if (trace->in->enabled)
> +		WARN_ON(usb_ep_disable(trace->in));
> +}
> +
> +static int ftrace_enable_endpoint(struct usb_ftrace *trace)
> +{
> +	if (trace->in->enabled)
> +		return 0;
> +
> +	return usb_ep_enable(trace->in);
> +}
> +
> +static int ftrace_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
> +{
> +	struct usb_ftrace		*trace = to_trace(f);
> +	struct usb_composite_dev	*cdev = f->config->cdev;
> +	int				ret;
> +
> +	if (alt != 0)
> +		goto fail;
> +
> +	if (intf != trace->intf_id)
> +		goto fail;
> +
> +	ftrace_disable_endpoint(trace);
> +
> +	if (!trace->in->desc) {
> +		ret = config_ep_by_speed(cdev->gadget, f, trace->in);
> +		if (ret) {
> +			trace->in->desc = NULL;
> +			goto fail;
> +		}
> +	}
> +
> +	ret = ftrace_enable_endpoint(trace);
> +	if (ret)
> +		goto fail;
> +
> +	return 0;
> +
> +fail:
> +	return -EINVAL;
> +}
> +
> +static int ftrace_bind(struct usb_configuration *c, struct usb_function *f)
> +{
> +	struct usb_composite_dev	*cdev = c->cdev;
> +	struct usb_ftrace		*trace = to_trace(f);
> +	struct usb_string		*us;
> +	struct usb_ep			*ep;
> +
> +	int				ret;
> +	int				i;
> +
> +	us = usb_gstrings_attach(cdev, ftrace_strings,
> +				 ARRAY_SIZE(ftrace_string_defs));
> +	if (IS_ERR(us))
> +		return PTR_ERR(us);
> +
> +	ftrace_intf_desc.iInterface = us[0].id;
> +
> +	ret = usb_interface_id(c, f);
> +	if (ret < 0)
> +		goto err0;
> +	trace->intf_id = ret;
> +	ftrace_intf_desc.bInterfaceNumber = ret;
> +
> +	ep = usb_ep_autoconfig(cdev->gadget, &ftrace_fs_in_desc);
> +	if (!ep)
> +		goto err0;
> +	trace->in = ep;
> +
> +	ftrace_hs_in_desc.bEndpointAddress = ftrace_fs_in_desc.bEndpointAddress;
> +	ftrace_ss_in_desc.bEndpointAddress = ftrace_fs_in_desc.bEndpointAddress;
> +
> +	trace->ftrace.write = ftrace_write;
> +
> +	spin_lock_init(&trace->lock);
> +	INIT_WORK(&trace->queue_work, ftrace_queue_work);
> +	INIT_LIST_HEAD(&trace->list);
> +	INIT_LIST_HEAD(&trace->pending);
> +	INIT_LIST_HEAD(&trace->queued);
> +
> +	ret = usb_assign_descriptors(f, ftrace_fs_function, ftrace_hs_function,
> +				     ftrace_ss_function, NULL);
> +	if (ret)
> +		goto err0;
> +
> +	for (i = 0; i < FTRACE_REQUEST_QUEUE_LENGTH; i++) {
> +		struct usb_request *req;
> +
> +		req = usb_ep_alloc_request(trace->in, GFP_KERNEL);
> +		if (!req)
> +			goto err1;
> +
> +		list_add_tail(&req->list, &trace->list);
> +	}
> +
> +	ret = register_ftrace_export(&trace->ftrace);
> +	if (ret)
> +		goto err1;
> +
> +	return 0;
> +
> +err1:
> +	while (!list_empty(&trace->list)) {
> +		struct usb_request *req = next_request(&trace->list);
> +
> +		usb_ep_free_request(trace->in, req);
> +		list_del(&req->list);
> +	}
> +
> +	usb_free_all_descriptors(f);
> +
> +err0:
> +	ERROR(cdev, "%s: can't bind --> err %d\n", f->name, ret);
> +
> +	return ret;
> +}
> +
> +static void ftrace_unbind(struct usb_configuration *c, struct usb_function *f)
> +{
> +	struct usb_ftrace		*trace = to_trace(f);
> +	struct usb_request		*req;
> +	struct usb_request		*tmp;
> +
> +	unregister_ftrace_export(&trace->ftrace);
> +	cancel_work_sync(&trace->queue_work);
> +	usb_free_all_descriptors(f);
> +
> +	list_for_each_entry(req, &trace->queued, list)
> +		usb_ep_dequeue(trace->in, req);
> +
> +	list_for_each_entry_safe(req, tmp, &trace->pending, list) {
> +		usb_ep_free_request(trace->in, req);
> +		list_del(&req->list);
> +	}
> +
> +	list_for_each_entry_safe(req, tmp, &trace->list, list) {
> +		usb_ep_free_request(trace->in, req);
> +		list_del(&req->list);
> +	}
> +}
> +
> +static void ftrace_disable(struct usb_function *f)
> +{
> +	struct usb_ftrace		*trace = to_trace(f);
> +
> +	ftrace_disable_endpoint(trace);
> +}
> +
> +static void ftrace_free_func(struct usb_function *f)
> +{
> +	kfree(to_trace(f));
> +}
> +
> +static struct config_item_type ftrace_func_type = {
> +	.ct_owner		= THIS_MODULE,
> +};
> +
> +static void ftrace_free_inst(struct usb_function_instance *fi)
> +{
> +	struct usb_ftrace_opts		*opts = to_opts(fi);
> +
> +	kfree(opts);
> +}
> +
> +static struct usb_function_instance *ftrace_alloc_inst(void)
> +{
> +	struct usb_ftrace_opts		*opts;
> +
> +	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
> +	if (!opts)
> +		return ERR_PTR(-ENOMEM);
> +
> +	opts->func_inst.free_func_inst = ftrace_free_inst;
> +
> +	config_group_init_type_name(&opts->func_inst.group, "",
> +				    &ftrace_func_type);
> +
> +	return &opts->func_inst;
> +}
> +
> +static struct usb_function *ftrace_alloc(struct usb_function_instance *fi)
> +{
> +	struct usb_ftrace		*trace;
> +
> +	trace = kzalloc(sizeof(*trace), GFP_KERNEL);
> +	if (!trace)
> +		return NULL;
> +
> +	trace->function.name = "ftrace";
> +	trace->function.bind = ftrace_bind;
> +	trace->function.unbind = ftrace_unbind;
> +	trace->function.set_alt = ftrace_set_alt;
> +	trace->function.disable = ftrace_disable;
> +	trace->function.strings = ftrace_strings;
> +	trace->function.free_func = ftrace_free_func;
> +
> +	return &trace->function;
> +}
> +
> +DECLARE_USB_FUNCTION_INIT(ftrace, ftrace_alloc_inst, ftrace_alloc);
> +MODULE_AUTHOR("Felipe Balbi <felipe.balbi@linux.intel.com>");
> +MODULE_LICENSE("GPL v2");

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#1662487

[Multipart message — attachments visible in raw view] — view raw

Hi,

Steven Rostedt <rostedt@goodmis.org> writes:
> On Fri,  9 Jun 2017 09:13:27 +0300
> Felipe Balbi <felipe.balbi@linux.intel.com> wrote:
>
>> Allow for ftrace data to be exported over a USB Gadget
>> Controller. With this, we have a potentially very fast pipe for
>> transmitting ftrace data to a Host PC for further analysis.
>> 
>> Note that in order to decode the data, one needs access to kernel
>> symbols in order to convert binary data into function names and what
>> not.
>> 
>
> Can you please explain what this is in a bit more detail. I have no
> idea what you are trying to accomplish.

this is just another ftrace export. Just like STM
(drivers/hwtracing/stm/ftrace.c), but I'm making use of a USB Peripheral
Controller that may be available.

> Also, do you mean ftrace as the internal Linux tracer (which should
> only be called "ftrace" or sometimes "Ftrace" but not "f_trace" or
> "FTrace", that just leads to more confusion.

heh, internal linux ftrace ;-) The driver name (f-trace.c) is just to
follow the convention of USB functions being name f_*.c or f-*.c. I
could call it f-ftrace.c, but seemed unnecessary.

> Or is this to do with http://www.ftrace.com/en/gb, a way to trace
> produce ;-)

heh :-) unlikely

-- 
balbi

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#1662545

On Fri, 09 Jun 2017 17:05:52 +0300
Felipe Balbi <felipe.balbi@linux.intel.com> wrote:

> Hi,
> 
> Steven Rostedt <rostedt@goodmis.org> writes:
> > On Fri,  9 Jun 2017 09:13:27 +0300
> > Felipe Balbi <felipe.balbi@linux.intel.com> wrote:
> >  
> >> Allow for ftrace data to be exported over a USB Gadget
> >> Controller. With this, we have a potentially very fast pipe for
> >> transmitting ftrace data to a Host PC for further analysis.
> >> 
> >> Note that in order to decode the data, one needs access to kernel
> >> symbols in order to convert binary data into function names and what
> >> not.
> >>   
> >
> > Can you please explain what this is in a bit more detail. I have no
> > idea what you are trying to accomplish.  
> 
> this is just another ftrace export. Just like STM
> (drivers/hwtracing/stm/ftrace.c), but I'm making use of a USB Peripheral
> Controller that may be available.
> 
> > Also, do you mean ftrace as the internal Linux tracer (which should
> > only be called "ftrace" or sometimes "Ftrace" but not "f_trace" or
> > "FTrace", that just leads to more confusion.  
> 
> heh, internal linux ftrace ;-) The driver name (f-trace.c) is just to
> follow the convention of USB functions being name f_*.c or f-*.c. I
> could call it f-ftrace.c, but seemed unnecessary.

OK, looking at the other files and functions in
drivers/usb/gadget/function, I see that F there is part of usb process.
OK, although it does make it somewhat confusing.

-- Steve

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