Commit cb5164ac authored by Jocelyn Falempe's avatar Jocelyn Falempe
Browse files

drm/panic: Add a QR code panic screen 



This patch adds a new panic screen, with a QR code and the kmsg data
embedded.
If DRM_PANIC_SCREEN_QR_CODE_URL is set, then the kmsg data will be
compressed with zlib and encoded as a numerical segment, and appended
to the URL as a URL parameter. This allows to save space, and put
about ~7500 bytes of kmsg data, in a V40 QR code.
Linux distributions can customize the URL, and put a web frontend to
directly open a bug report with the kmsg data.

Otherwise the kmsg data will be encoded as a binary segment (ie raw
ascii) and only a maximum of 2953 bytes of kmsg data will be
available in the QR code.

You can also limit the QR code size with DRM_PANIC_SCREEN_QR_VERSION.

Signed-off-by: default avatarJocelyn Falempe <jfalempe@redhat.com>
Reviewed-by: default avatarAlice Ryhl <aliceryhl@google.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240822073852.562286-5-jfalempe@redhat.com
parent 8f4eca6a

drivers/gpu/drm/Kconfig

+31 −0
Original line number Diff line number Diff line
@@ -149,6 +149,37 @@ config DRM_PANIC_SCREEN 
	  or by writing to /sys/module/drm/parameters/panic_screen sysfs entry

	  Default is "user"



config DRM_PANIC_SCREEN_QR_CODE

	bool "Add a panic screen with a QR code"

	depends on DRM_PANIC && RUST

	help

	  This option adds a QR code generator, and a panic screen with a QR

	  code. The QR code will contain the last lines of kmsg and other debug

	  information. This should be easier for the user to report a kernel

	  panic, with all debug information available.

	  To use this panic screen, also set DRM_PANIC_SCREEN to "qr_code"



config DRM_PANIC_SCREEN_QR_CODE_URL

	string "Base URL of the QR code in the panic screen"

	depends on DRM_PANIC_SCREEN_QR_CODE

	help

	  This option sets the base URL to report the kernel panic. If it's set

	  the QR code will contain the URL and the kmsg compressed with zlib as

	  a URL parameter. If it's empty, the QR code will contain the kmsg as

	  uncompressed text only.

	  There is a demo code in javascript, to decode and uncompress the kmsg

	  data from the URL parameter at https://github.com/kdj0c/panic_report



config DRM_PANIC_SCREEN_QR_VERSION

	int "Maximum version (size) of the QR code."

	depends on DRM_PANIC_SCREEN_QR_CODE

	default 40

	help

	  This option limits the version (or size) of the QR code. QR code

	  version ranges from Version 1 (21x21) to Version 40 (177x177).

	  Smaller QR code are easier to read, but will contain less debugging

	  data. Default is 40.



config DRM_DEBUG_DP_MST_TOPOLOGY_REFS

        bool "Enable refcount backtrace history in the DP MST helpers"

	depends on STACKTRACE_SUPPORT

drivers/gpu/drm/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -89,6 +89,7 @@ drm-$(CONFIG_DRM_PRIVACY_SCREEN) += \ 
	drm_privacy_screen_x86.o

drm-$(CONFIG_DRM_ACCEL) += ../../accel/drm_accel.o

drm-$(CONFIG_DRM_PANIC) += drm_panic.o

drm-$(CONFIG_DRM_PANIC_SCREEN_QR_CODE) += drm_panic_qr.o

obj-$(CONFIG_DRM)	+= drm.o



obj-$(CONFIG_DRM_PANEL_ORIENTATION_QUIRKS) += drm_panel_orientation_quirks.o

drivers/gpu/drm/drm_crtc_internal.h

+4 −0
Original line number Diff line number Diff line
@@ -320,10 +320,14 @@ drm_edid_load_firmware(struct drm_connector *connector) 
bool drm_panic_is_enabled(struct drm_device *dev);

void drm_panic_register(struct drm_device *dev);

void drm_panic_unregister(struct drm_device *dev);

void drm_panic_init(void);

void drm_panic_exit(void);

#else

static inline bool drm_panic_is_enabled(struct drm_device *dev) { return false; }

static inline void drm_panic_register(struct drm_device *dev) {}

static inline void drm_panic_unregister(struct drm_device *dev) {}

static inline void drm_panic_init(void) {}

static inline void drm_panic_exit(void) {}

#endif



#endif /* __DRM_CRTC_INTERNAL_H__ */

drivers/gpu/drm/drm_drv.c

+3 −0
Original line number Diff line number Diff line
@@ -1067,6 +1067,7 @@ static const struct file_operations drm_stub_fops = { 
static void drm_core_exit(void)

{

	drm_privacy_screen_lookup_exit();

	drm_panic_exit();

	accel_core_exit();

	unregister_chrdev(DRM_MAJOR, "drm");

	debugfs_remove(drm_debugfs_root);
@@ -1099,6 +1100,8 @@ static int __init drm_core_init(void) 
	if (ret < 0)

		goto error;



	drm_panic_init();



	drm_privacy_screen_lookup_init();



	drm_core_init_complete = true;

drivers/gpu/drm/drm_panic.c

+248 −0
Original line number Diff line number Diff line
@@ -18,6 +18,8 @@ 
#include <linux/overflow.h>

#include <linux/printk.h>

#include <linux/types.h>

#include <linux/utsname.h>

#include <linux/zlib.h>



#include <drm/drm_drv.h>

#include <drm/drm_fourcc.h>
@@ -26,6 +28,7 @@ 
#include <drm/drm_panic.h>

#include <drm/drm_plane.h>

#include <drm/drm_print.h>

#include <drm/drm_rect.h>



#include "drm_crtc_internal.h"
@@ -627,6 +630,233 @@ static void draw_panic_static_kmsg(struct drm_scanout_buffer *sb) 
	}

}



#if defined(CONFIG_DRM_PANIC_SCREEN_QR_CODE)

/*

 * It is unwise to allocate memory in the panic callback, so the buffers are

 * pre-allocated. Only 2 buffers and the zlib workspace are needed.

 * Two buffers are enough, using the following buffer usage:

 * 1) kmsg messages are dumped in buffer1

 * 2) kmsg is zlib-compressed into buffer2

 * 3) compressed kmsg is encoded as QR-code Numeric stream in buffer1

 * 4) QR-code image is generated in buffer2

 * The Max QR code size is V40, 177x177, 4071 bytes for image, 2956 bytes for

 * data segments.

 *

 * Typically, ~7500 bytes of kmsg, are compressed into 2800 bytes, which fits in

 * a V40 QR-code (177x177).

 *

 * If CONFIG_DRM_PANIC_SCREEN_QR_CODE_URL is not set, the kmsg data will be put

 * directly in the QR code.

 * 1) kmsg messages are dumped in buffer1

 * 2) kmsg message is encoded as byte stream in buffer2

 * 3) QR-code image is generated in buffer1

 */



static uint panic_qr_version = CONFIG_DRM_PANIC_SCREEN_QR_VERSION;

module_param(panic_qr_version, uint, 0644);

MODULE_PARM_DESC(panic_qr_version, "maximum version (size) of the QR code");



#define MAX_QR_DATA 2956

#define MAX_ZLIB_RATIO 3

#define QR_BUFFER1_SIZE (MAX_ZLIB_RATIO * MAX_QR_DATA) /* Must also be > 4071  */

#define QR_BUFFER2_SIZE 4096

#define QR_MARGIN	4	/* 4 modules of foreground color around the qr code */



/* Compression parameters */

#define COMPR_LEVEL 6

#define WINDOW_BITS 12

#define MEM_LEVEL 4



static char *qrbuf1;

static char *qrbuf2;

static struct z_stream_s stream;



static void __init drm_panic_qr_init(void)

{

	qrbuf1 = kmalloc(QR_BUFFER1_SIZE, GFP_KERNEL);

	qrbuf2 = kmalloc(QR_BUFFER2_SIZE, GFP_KERNEL);

	stream.workspace = kmalloc(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),

				   GFP_KERNEL);

}



static void drm_panic_qr_exit(void)

{

	kfree(qrbuf1);

	qrbuf1 = NULL;

	kfree(qrbuf2);

	qrbuf2 = NULL;

	kfree(stream.workspace);

	stream.workspace = NULL;

}



extern size_t drm_panic_qr_max_data_size(u8 version, size_t url_len);



extern u8 drm_panic_qr_generate(const char *url, u8 *data, size_t data_len, size_t data_size,

				u8 *tmp, size_t tmp_size);



static int drm_panic_get_qr_code_url(u8 **qr_image)

{

	struct kmsg_dump_iter iter;

	char url[256];

	size_t kmsg_len, max_kmsg_size;

	char *kmsg;

	int max_qr_data_size, url_len;



	url_len = snprintf(url, sizeof(url), CONFIG_DRM_PANIC_SCREEN_QR_CODE_URL "?a=%s&v=%s&zl=",

			   utsname()->machine, utsname()->release);



	max_qr_data_size = drm_panic_qr_max_data_size(panic_qr_version, url_len);

	max_kmsg_size = min(MAX_ZLIB_RATIO * max_qr_data_size, QR_BUFFER1_SIZE);



	/* get kmsg to buffer 1 */

	kmsg_dump_rewind(&iter);

	kmsg_dump_get_buffer(&iter, false, qrbuf1, max_kmsg_size, &kmsg_len);



	if (!kmsg_len)

		return -ENODATA;

	kmsg = qrbuf1;



try_again:

	if (zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,

			      MEM_LEVEL, Z_DEFAULT_STRATEGY) != Z_OK)

		return -EINVAL;



	stream.next_in = kmsg;

	stream.avail_in = kmsg_len;

	stream.total_in = 0;

	stream.next_out = qrbuf2;

	stream.avail_out = QR_BUFFER2_SIZE;

	stream.total_out = 0;



	if (zlib_deflate(&stream, Z_FINISH) != Z_STREAM_END)

		return -EINVAL;



	if (zlib_deflateEnd(&stream) != Z_OK)

		return -EINVAL;



	if (stream.total_out > max_qr_data_size) {

		/* too much data for the QR code, so skip the first line and try again */

		kmsg = strchr(kmsg, '\n');

		if (!kmsg)

			return -EINVAL;

		/* skip the first \n */

		kmsg += 1;

		kmsg_len = strlen(kmsg);

		goto try_again;

	}

	*qr_image = qrbuf2;



	/* generate qr code image in buffer2 */

	return drm_panic_qr_generate(url, qrbuf2, stream.total_out, QR_BUFFER2_SIZE,

				     qrbuf1, QR_BUFFER1_SIZE);

}



static int drm_panic_get_qr_code_raw(u8 **qr_image)

{

	struct kmsg_dump_iter iter;

	size_t kmsg_len;

	size_t max_kmsg_size = min(drm_panic_qr_max_data_size(panic_qr_version, 0),

				   QR_BUFFER1_SIZE);



	kmsg_dump_rewind(&iter);

	kmsg_dump_get_buffer(&iter, false, qrbuf1, max_kmsg_size, &kmsg_len);

	if (!kmsg_len)

		return -ENODATA;



	*qr_image = qrbuf1;

	return drm_panic_qr_generate(NULL, qrbuf1, kmsg_len, QR_BUFFER1_SIZE,

				     qrbuf2, QR_BUFFER2_SIZE);

}



static int drm_panic_get_qr_code(u8 **qr_image)

{

	if (strlen(CONFIG_DRM_PANIC_SCREEN_QR_CODE_URL) > 0)

		return drm_panic_get_qr_code_url(qr_image);

	else

		return drm_panic_get_qr_code_raw(qr_image);

}



/*

 * Draw the panic message at the center of the screen, with a QR Code

 */

static int _draw_panic_static_qr_code(struct drm_scanout_buffer *sb)

{

	u32 fg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR, sb->format->format);

	u32 bg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR, sb->format->format);

	const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);

	struct drm_rect r_screen, r_logo, r_msg, r_qr, r_qr_canvas;

	unsigned int max_qr_size, scale;

	unsigned int msg_width, msg_height;

	int qr_width, qr_canvas_width, qr_pitch, v_margin;

	u8 *qr_image;



	if (!font || !qrbuf1 || !qrbuf2 || !stream.workspace)

		return -ENOMEM;



	r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);



	drm_panic_logo_rect(&r_logo, font);



	msg_width = min(get_max_line_len(panic_msg, panic_msg_lines) * font->width, sb->width);

	msg_height = min(panic_msg_lines * font->height, sb->height);

	r_msg = DRM_RECT_INIT(0, 0, msg_width, msg_height);



	max_qr_size = min(3 * sb->width / 4, 3 * sb->height / 4);



	qr_width = drm_panic_get_qr_code(&qr_image);

	if (qr_width <= 0)

		return -ENOSPC;



	qr_canvas_width = qr_width + QR_MARGIN * 2;

	scale = max_qr_size / qr_canvas_width;

	/* QR code is not readable if not scaled at least by 2 */

	if (scale < 2)

		return -ENOSPC;



	pr_debug("QR width %d and scale %d\n", qr_width, scale);

	r_qr_canvas = DRM_RECT_INIT(0, 0, qr_canvas_width * scale, qr_canvas_width * scale);



	v_margin = (sb->height - drm_rect_height(&r_qr_canvas) - drm_rect_height(&r_msg)) / 5;



	drm_rect_translate(&r_qr_canvas, (sb->width - r_qr_canvas.x2) / 2, 2 * v_margin);

	r_qr = DRM_RECT_INIT(r_qr_canvas.x1 + QR_MARGIN * scale, r_qr_canvas.y1 + QR_MARGIN * scale,

			     qr_width * scale, qr_width * scale);



	/* Center the panic message */

	drm_rect_translate(&r_msg, (sb->width - r_msg.x2) / 2,

			   3 * v_margin + drm_rect_height(&r_qr_canvas));



	/* Fill with the background color, and draw text on top */

	drm_panic_fill(sb, &r_screen, bg_color);



	if (!drm_rect_overlap(&r_logo, &r_msg) && !drm_rect_overlap(&r_logo, &r_qr))

		drm_panic_logo_draw(sb, &r_logo, font, fg_color);



	draw_txt_rectangle(sb, font, panic_msg, panic_msg_lines, true, &r_msg, fg_color);



	/* Draw the qr code */

	qr_pitch = DIV_ROUND_UP(qr_width, 8);

	drm_panic_fill(sb, &r_qr_canvas, fg_color);

	drm_panic_fill(sb, &r_qr, bg_color);

	drm_panic_blit(sb, &r_qr, qr_image, qr_pitch, scale, fg_color);

	return 0;

}



static void draw_panic_static_qr_code(struct drm_scanout_buffer *sb)

{

	if (_draw_panic_static_qr_code(sb))

		draw_panic_static_user(sb);

}

#else

static void draw_panic_static_qr_code(struct drm_scanout_buffer *sb)

{

	draw_panic_static_user(sb);

}



static void drm_panic_qr_init(void) {};

static void drm_panic_qr_exit(void) {};

#endif



/*

 * drm_panic_is_format_supported()

 * @format: a fourcc color code
@@ -645,6 +875,8 @@ static void draw_panic_dispatch(struct drm_scanout_buffer *sb) 
{

	if (!strcmp(drm_panic_screen, "kmsg")) {

		draw_panic_static_kmsg(sb);

	} else if (!strcmp(drm_panic_screen, "qr_code")) {

		draw_panic_static_qr_code(sb);

	} else {

		draw_panic_static_user(sb);

	}
@@ -814,3 +1046,19 @@ void drm_panic_unregister(struct drm_device *dev) 
		kmsg_dump_unregister(&plane->kmsg_panic);

	}

}



/**

 * drm_panic_init() - initialize DRM panic.

 */

void __init drm_panic_init(void)

{

	drm_panic_qr_init();

}



/**

 * drm_panic_exit() - Free the resources taken by drm_panic_exit()

 */

void drm_panic_exit(void)

{

	drm_panic_qr_exit();

}