drm_panic.c

   1// SPDX-License-Identifier: GPL-2.0 or MIT
   2/*
   3 * Copyright (c) 2023 Red Hat.
   4 * Author: Jocelyn Falempe <jfalempe@redhat.com>
   5 * inspired by the drm_log driver from David Herrmann <dh.herrmann@gmail.com>
   6 * Tux Ascii art taken from cowsay written by Tony Monroe
   7 */
   8
   9#include <linux/export.h>
  10#include <linux/font.h>
  11#include <linux/highmem.h>
  12#include <linux/init.h>
  13#include <linux/iosys-map.h>
  14#include <linux/kdebug.h>
  15#include <linux/kmsg_dump.h>
  16#include <linux/linux_logo.h>
  17#include <linux/list.h>
  18#include <linux/math.h>
  19#include <linux/module.h>
  20#include <linux/overflow.h>
  21#include <linux/printk.h>
  22#include <linux/types.h>
  23#include <linux/utsname.h>
  24#include <linux/zlib.h>
  25
  26#include <drm/drm_drv.h>
  27#include <drm/drm_fourcc.h>
  28#include <drm/drm_framebuffer.h>
  29#include <drm/drm_modeset_helper_vtables.h>
  30#include <drm/drm_panic.h>
  31#include <drm/drm_plane.h>
  32#include <drm/drm_print.h>
  33#include <drm/drm_rect.h>
  34
  35#include "drm_crtc_internal.h"
  36#include "drm_draw_internal.h"
  37
  38MODULE_AUTHOR("Jocelyn Falempe");
  39MODULE_DESCRIPTION("DRM panic handler");
  40MODULE_LICENSE("GPL");
  41
  42static char drm_panic_screen[16] = CONFIG_DRM_PANIC_SCREEN;
  43module_param_string(panic_screen, drm_panic_screen, sizeof(drm_panic_screen), 0644);
  44MODULE_PARM_DESC(panic_screen,
  45		 "Choose what will be displayed by drm_panic, 'user' or 'kmsg' [default="
  46		 CONFIG_DRM_PANIC_SCREEN "]");
  47
  48/**
  49 * DOC: overview
  50 *
  51 * To enable DRM panic for a driver, the primary plane must implement a
  52 * &drm_plane_helper_funcs.get_scanout_buffer helper function. It is then
  53 * automatically registered to the drm panic handler.
  54 * When a panic occurs, the &drm_plane_helper_funcs.get_scanout_buffer will be
  55 * called, and the driver can provide a framebuffer so the panic handler can
  56 * draw the panic screen on it. Currently only linear buffer and a few color
  57 * formats are supported.
  58 * Optionally the driver can also provide a &drm_plane_helper_funcs.panic_flush
  59 * callback, that will be called after that, to send additional commands to the
  60 * hardware to make the scanout buffer visible.
  61 */
  62
  63/*
  64 * This module displays a user friendly message on screen when a kernel panic
  65 * occurs. This is conflicting with fbcon, so you can only enable it when fbcon
  66 * is disabled.
  67 * It's intended for end-user, so have minimal technical/debug information.
  68 *
  69 * Implementation details:
  70 *
  71 * It is a panic handler, so it can't take lock, allocate memory, run tasks/irq,
  72 * or attempt to sleep. It's a best effort, and it may not be able to display
  73 * the message in all situations (like if the panic occurs in the middle of a
  74 * modesetting).
  75 * It will display only one static frame, so performance optimizations are low
  76 * priority as the machine is already in an unusable state.
  77 */
  78
  79struct drm_panic_line {
  80	u32 len;
  81	const char *txt;
  82};
  83
  84#define PANIC_LINE(s) {.len = sizeof(s) - 1, .txt = s}
  85
  86static struct drm_panic_line panic_msg[] = {
  87	PANIC_LINE("KERNEL PANIC!"),
  88	PANIC_LINE(""),
  89	PANIC_LINE("Please reboot your computer."),
  90	PANIC_LINE(""),
  91	PANIC_LINE(""), /* will be replaced by the panic description */
  92};
  93
  94static const size_t panic_msg_lines = ARRAY_SIZE(panic_msg);
  95
  96static const struct drm_panic_line logo_ascii[] = {
  97	PANIC_LINE("     .--.        _"),
  98	PANIC_LINE("    |o_o |      | |"),
  99	PANIC_LINE("    |:_/ |      | |"),
 100	PANIC_LINE("   //   \\ \\     |_|"),
 101	PANIC_LINE("  (|     | )     _"),
 102	PANIC_LINE(" /'\\_   _/`\\    (_)"),
 103	PANIC_LINE(" \\___)=(___/"),
 104};
 105
 106static const size_t logo_ascii_lines = ARRAY_SIZE(logo_ascii);
 107
 108#if defined(CONFIG_LOGO) && !defined(MODULE)
 109static const struct linux_logo *logo_mono;
 110
 111static int drm_panic_setup_logo(void)
 112{
 113	const struct linux_logo *logo = fb_find_logo(1);
 114	const unsigned char *logo_data;
 115	struct linux_logo *logo_dup;
 116
 117	if (!logo || logo->type != LINUX_LOGO_MONO)
 118		return 0;
 119
 120	/* The logo is __init, so we must make a copy for later use */
 121	logo_data = kmemdup(logo->data,
 122			    size_mul(DIV_ROUND_UP(logo->width, BITS_PER_BYTE), logo->height),
 123			    GFP_KERNEL);
 124	if (!logo_data)
 125		return -ENOMEM;
 126
 127	logo_dup = kmemdup(logo, sizeof(*logo), GFP_KERNEL);
 128	if (!logo_dup) {
 129		kfree(logo_data);
 130		return -ENOMEM;
 131	}
 132
 133	logo_dup->data = logo_data;
 134	logo_mono = logo_dup;
 135
 136	return 0;
 137}
 138
 139device_initcall(drm_panic_setup_logo);
 140#else
 141#define logo_mono	((const struct linux_logo *)NULL)
 142#endif
 143
 144/*
 145 *  Blit & Fill functions
 146 */
 147static void drm_panic_blit_pixel(struct drm_scanout_buffer *sb, struct drm_rect *clip,
 148				 const u8 *sbuf8, unsigned int spitch, unsigned int scale,
 149				 u32 fg_color)
 150{
 151	unsigned int y, x;
 152
 153	for (y = 0; y < drm_rect_height(clip); y++)
 154		for (x = 0; x < drm_rect_width(clip); x++)
 155			if (drm_draw_is_pixel_fg(sbuf8, spitch, x / scale, y / scale))
 156				sb->set_pixel(sb, clip->x1 + x, clip->y1 + y, fg_color);
 157}
 158
 159static void drm_panic_write_pixel16(void *vaddr, unsigned int offset, u16 color)
 160{
 161	u16 *p = vaddr + offset;
 162
 163	*p = color;
 164}
 165
 166static void drm_panic_write_pixel24(void *vaddr, unsigned int offset, u32 color)
 167{
 168	u8 *p = vaddr + offset;
 169
 170	*p++ = color & 0xff;
 171	color >>= 8;
 172	*p++ = color & 0xff;
 173	color >>= 8;
 174	*p = color & 0xff;
 175}
 176
 177/*
 178 * Special case if the pixel crosses page boundaries
 179 */
 180static void drm_panic_write_pixel24_xpage(void *vaddr, struct page *next_page,
 181					  unsigned int offset, u32 color)
 182{
 183	u8 *vaddr2;
 184	u8 *p = vaddr + offset;
 185
 186	vaddr2 = kmap_local_page_try_from_panic(next_page);
 187
 188	*p++ = color & 0xff;
 189	color >>= 8;
 190
 191	if (offset == PAGE_SIZE - 1)
 192		p = vaddr2;
 193
 194	*p++ = color & 0xff;
 195	color >>= 8;
 196
 197	if (offset == PAGE_SIZE - 2)
 198		p = vaddr2;
 199
 200	*p = color & 0xff;
 201	kunmap_local(vaddr2);
 202}
 203
 204static void drm_panic_write_pixel32(void *vaddr, unsigned int offset, u32 color)
 205{
 206	u32 *p = vaddr + offset;
 207
 208	*p = color;
 209}
 210
 211static void drm_panic_write_pixel(void *vaddr, unsigned int offset, u32 color, unsigned int cpp)
 212{
 213	switch (cpp) {
 214	case 2:
 215		drm_panic_write_pixel16(vaddr, offset, color);
 216		break;
 217	case 3:
 218		drm_panic_write_pixel24(vaddr, offset, color);
 219		break;
 220	case 4:
 221		drm_panic_write_pixel32(vaddr, offset, color);
 222		break;
 223	default:
 224		pr_debug_once("Can't blit with pixel width %d\n", cpp);
 225	}
 226}
 227
 228/*
 229 * The scanout buffer pages are not mapped, so for each pixel,
 230 * use kmap_local_page_try_from_panic() to map the page, and write the pixel.
 231 * Try to keep the map from the previous pixel, to avoid too much map/unmap.
 232 */
 233static void drm_panic_blit_page(struct page **pages, unsigned int dpitch,
 234				unsigned int cpp, const u8 *sbuf8,
 235				unsigned int spitch, struct drm_rect *clip,
 236				unsigned int scale, u32 fg32)
 237{
 238	unsigned int y, x;
 239	unsigned int page = ~0;
 240	unsigned int height = drm_rect_height(clip);
 241	unsigned int width = drm_rect_width(clip);
 242	void *vaddr = NULL;
 243
 244	for (y = 0; y < height; y++) {
 245		for (x = 0; x < width; x++) {
 246			if (drm_draw_is_pixel_fg(sbuf8, spitch, x / scale, y / scale)) {
 247				unsigned int new_page;
 248				unsigned int offset;
 249
 250				offset = (y + clip->y1) * dpitch + (x + clip->x1) * cpp;
 251				new_page = offset >> PAGE_SHIFT;
 252				offset = offset % PAGE_SIZE;
 253				if (new_page != page) {
 254					if (!pages[new_page])
 255						continue;
 256					if (vaddr)
 257						kunmap_local(vaddr);
 258					page = new_page;
 259					vaddr = kmap_local_page_try_from_panic(pages[page]);
 260				}
 261				if (!vaddr)
 262					continue;
 263
 264				// Special case for 24bit, as a pixel might cross page boundaries
 265				if (cpp == 3 && offset + 3 > PAGE_SIZE)
 266					drm_panic_write_pixel24_xpage(vaddr, pages[page + 1],
 267								      offset, fg32);
 268				else
 269					drm_panic_write_pixel(vaddr, offset, fg32, cpp);
 270			}
 271		}
 272	}
 273	if (vaddr)
 274		kunmap_local(vaddr);
 275}
 276
 277/*
 278 * drm_panic_blit - convert a monochrome image to a linear framebuffer
 279 * @sb: destination scanout buffer
 280 * @clip: destination rectangle
 281 * @sbuf8: source buffer, in monochrome format, 8 pixels per byte.
 282 * @spitch: source pitch in bytes
 283 * @scale: integer scale, source buffer is scale time smaller than destination
 284 *         rectangle
 285 * @fg_color: foreground color, in destination format
 286 *
 287 * This can be used to draw a font character, which is a monochrome image, to a
 288 * framebuffer in other supported format.
 289 */
 290static void drm_panic_blit(struct drm_scanout_buffer *sb, struct drm_rect *clip,
 291			   const u8 *sbuf8, unsigned int spitch,
 292			   unsigned int scale, u32 fg_color)
 293
 294{
 295	struct iosys_map map;
 296
 297	if (sb->set_pixel)
 298		return drm_panic_blit_pixel(sb, clip, sbuf8, spitch, scale, fg_color);
 299
 300	if (sb->pages)
 301		return drm_panic_blit_page(sb->pages, sb->pitch[0], sb->format->cpp[0],
 302					   sbuf8, spitch, clip, scale, fg_color);
 303
 304	map = sb->map[0];
 305	iosys_map_incr(&map, clip->y1 * sb->pitch[0] + clip->x1 * sb->format->cpp[0]);
 306
 307	switch (sb->format->cpp[0]) {
 308	case 2:
 309		drm_draw_blit16(&map, sb->pitch[0], sbuf8, spitch,
 310				drm_rect_height(clip), drm_rect_width(clip), scale, fg_color);
 311	break;
 312	case 3:
 313		drm_draw_blit24(&map, sb->pitch[0], sbuf8, spitch,
 314				drm_rect_height(clip), drm_rect_width(clip), scale, fg_color);
 315	break;
 316	case 4:
 317		drm_draw_blit32(&map, sb->pitch[0], sbuf8, spitch,
 318				drm_rect_height(clip), drm_rect_width(clip), scale, fg_color);
 319	break;
 320	default:
 321		WARN_ONCE(1, "Can't blit with pixel width %d\n", sb->format->cpp[0]);
 322	}
 323}
 324
 325static void drm_panic_fill_pixel(struct drm_scanout_buffer *sb,
 326				 struct drm_rect *clip,
 327				 u32 color)
 328{
 329	unsigned int y, x;
 330
 331	for (y = 0; y < drm_rect_height(clip); y++)
 332		for (x = 0; x < drm_rect_width(clip); x++)
 333			sb->set_pixel(sb, clip->x1 + x, clip->y1 + y, color);
 334}
 335
 336static void drm_panic_fill_page(struct page **pages, unsigned int dpitch,
 337				unsigned int cpp, struct drm_rect *clip,
 338				u32 color)
 339{
 340	unsigned int y, x;
 341	unsigned int page = ~0;
 342	void *vaddr = NULL;
 343
 344	for (y = clip->y1; y < clip->y2; y++) {
 345		for (x = clip->x1; x < clip->x2; x++) {
 346			unsigned int new_page;
 347			unsigned int offset;
 348
 349			offset = y * dpitch + x * cpp;
 350			new_page = offset >> PAGE_SHIFT;
 351			offset = offset % PAGE_SIZE;
 352			if (new_page != page) {
 353				if (vaddr)
 354					kunmap_local(vaddr);
 355				page = new_page;
 356				vaddr = kmap_local_page_try_from_panic(pages[page]);
 357			}
 358			if (!vaddr)
 359				continue;
 360
 361			// Special case for 24bit, as a pixel might cross page boundaries
 362			if (cpp == 3 && offset + 3 > PAGE_SIZE)
 363				drm_panic_write_pixel24_xpage(vaddr, pages[page + 1],
 364							      offset, color);
 365			else
 366				drm_panic_write_pixel(vaddr, offset, color, cpp);
 367		}
 368	}
 369	if (vaddr)
 370		kunmap_local(vaddr);
 371}
 372
 373/*
 374 * drm_panic_fill - Fill a rectangle with a color
 375 * @sb: destination scanout buffer
 376 * @clip: destination rectangle
 377 * @color: foreground color, in destination format
 378 *
 379 * Fill a rectangle with a color, in a linear framebuffer.
 380 */
 381static void drm_panic_fill(struct drm_scanout_buffer *sb, struct drm_rect *clip,
 382			   u32 color)
 383{
 384	struct iosys_map map;
 385
 386	if (sb->set_pixel)
 387		return drm_panic_fill_pixel(sb, clip, color);
 388
 389	if (sb->pages)
 390		return drm_panic_fill_page(sb->pages, sb->pitch[0], sb->format->cpp[0],
 391					   clip, color);
 392
 393	map = sb->map[0];
 394	iosys_map_incr(&map, clip->y1 * sb->pitch[0] + clip->x1 * sb->format->cpp[0]);
 395
 396	switch (sb->format->cpp[0]) {
 397	case 2:
 398		drm_draw_fill16(&map, sb->pitch[0], drm_rect_height(clip),
 399				drm_rect_width(clip), color);
 400	break;
 401	case 3:
 402		drm_draw_fill24(&map, sb->pitch[0], drm_rect_height(clip),
 403				drm_rect_width(clip), color);
 404	break;
 405	case 4:
 406		drm_draw_fill32(&map, sb->pitch[0], drm_rect_height(clip),
 407				drm_rect_width(clip), color);
 408	break;
 409	default:
 410		WARN_ONCE(1, "Can't fill with pixel width %d\n", sb->format->cpp[0]);
 411	}
 412}
 413
 414static unsigned int get_max_line_len(const struct drm_panic_line *lines, int len)
 415{
 416	int i;
 417	unsigned int max = 0;
 418
 419	for (i = 0; i < len; i++)
 420		max = max(lines[i].len, max);
 421	return max;
 422}
 423
 424/*
 425 * Draw a text in a rectangle on a framebuffer. The text is truncated if it overflows the rectangle
 426 */
 427static void draw_txt_rectangle(struct drm_scanout_buffer *sb,
 428			       const struct font_desc *font,
 429			       const struct drm_panic_line *msg,
 430			       unsigned int msg_lines,
 431			       bool centered,
 432			       struct drm_rect *clip,
 433			       u32 color)
 434{
 435	int i, j;
 436	const u8 *src;
 437	size_t font_pitch = DIV_ROUND_UP(font->width, 8);
 438	struct drm_rect rec;
 439
 440	msg_lines = min(msg_lines,  drm_rect_height(clip) / font->height);
 441	for (i = 0; i < msg_lines; i++) {
 442		size_t line_len = min(msg[i].len, drm_rect_width(clip) / font->width);
 443
 444		rec.y1 = clip->y1 +  i * font->height;
 445		rec.y2 = rec.y1 + font->height;
 446		rec.x1 = clip->x1;
 447
 448		if (centered)
 449			rec.x1 += (drm_rect_width(clip) - (line_len * font->width)) / 2;
 450
 451		for (j = 0; j < line_len; j++) {
 452			src = drm_draw_get_char_bitmap(font, msg[i].txt[j], font_pitch);
 453			rec.x2 = rec.x1 + font->width;
 454			drm_panic_blit(sb, &rec, src, font_pitch, 1, color);
 455			rec.x1 += font->width;
 456		}
 457	}
 458}
 459
 460static void drm_panic_logo_rect(struct drm_rect *rect, const struct font_desc *font)
 461{
 462	if (logo_mono) {
 463		drm_rect_init(rect, 0, 0, logo_mono->width, logo_mono->height);
 464	} else {
 465		int logo_width = get_max_line_len(logo_ascii, logo_ascii_lines) * font->width;
 466
 467		drm_rect_init(rect, 0, 0, logo_width, logo_ascii_lines * font->height);
 468	}
 469}
 470
 471static void drm_panic_logo_draw(struct drm_scanout_buffer *sb, struct drm_rect *rect,
 472				const struct font_desc *font, u32 fg_color)
 473{
 474	if (rect->x2 > sb->width || rect->y2 > sb->height)
 475		return;
 476
 477	if (logo_mono)
 478		drm_panic_blit(sb, rect, logo_mono->data,
 479			       DIV_ROUND_UP(drm_rect_width(rect), 8), 1, fg_color);
 480	else
 481		draw_txt_rectangle(sb, font, logo_ascii, logo_ascii_lines, false, rect,
 482				   fg_color);
 483}
 484
 485static void draw_panic_static_user(struct drm_scanout_buffer *sb)
 486{
 487	u32 fg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR,
 488						    sb->format->format);
 489	u32 bg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR,
 490						    sb->format->format);
 491	const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
 492	struct drm_rect r_screen, r_logo, r_msg;
 493	unsigned int msg_width, msg_height;
 494
 495	if (!font)
 496		return;
 497
 498	r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);
 499	drm_panic_logo_rect(&r_logo, font);
 500
 501	msg_width = min(get_max_line_len(panic_msg, panic_msg_lines) * font->width, sb->width);
 502	msg_height = min(panic_msg_lines * font->height, sb->height);
 503	r_msg = DRM_RECT_INIT(0, 0, msg_width, msg_height);
 504
 505	/* Center the panic message */
 506	drm_rect_translate(&r_msg, (sb->width - r_msg.x2) / 2, (sb->height - r_msg.y2) / 2);
 507
 508	/* Fill with the background color, and draw text on top */
 509	drm_panic_fill(sb, &r_screen, bg_color);
 510
 511	if (!drm_rect_overlap(&r_logo, &r_msg))
 512		drm_panic_logo_draw(sb, &r_logo, font, fg_color);
 513
 514	draw_txt_rectangle(sb, font, panic_msg, panic_msg_lines, true, &r_msg, fg_color);
 515}
 516
 517/*
 518 * Draw one line of kmsg, and handle wrapping if it won't fit in the screen width.
 519 * Return the y-offset of the next line.
 520 */
 521static int draw_line_with_wrap(struct drm_scanout_buffer *sb, const struct font_desc *font,
 522			       struct drm_panic_line *line, int yoffset, u32 fg_color)
 523{
 524	int chars_per_row = sb->width / font->width;
 525	struct drm_rect r_txt = DRM_RECT_INIT(0, yoffset, sb->width, font->height);
 526	struct drm_panic_line line_wrap;
 527
 528	if (line->len > chars_per_row) {
 529		line_wrap.len = line->len % chars_per_row;
 530		line_wrap.txt = line->txt + line->len - line_wrap.len;
 531		draw_txt_rectangle(sb, font, &line_wrap, 1, false, &r_txt, fg_color);
 532		r_txt.y1 -= font->height;
 533		if (r_txt.y1 < 0)
 534			return r_txt.y1;
 535		while (line_wrap.txt > line->txt) {
 536			line_wrap.txt -= chars_per_row;
 537			line_wrap.len = chars_per_row;
 538			draw_txt_rectangle(sb, font, &line_wrap, 1, false, &r_txt, fg_color);
 539			r_txt.y1 -= font->height;
 540			if (r_txt.y1 < 0)
 541				return r_txt.y1;
 542		}
 543	} else {
 544		draw_txt_rectangle(sb, font, line, 1, false, &r_txt, fg_color);
 545		r_txt.y1 -= font->height;
 546	}
 547	return r_txt.y1;
 548}
 549
 550/*
 551 * Draw the kmsg buffer to the screen, starting from the youngest message at the bottom,
 552 * and going up until reaching the top of the screen.
 553 */
 554static void draw_panic_static_kmsg(struct drm_scanout_buffer *sb)
 555{
 556	u32 fg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR,
 557						    sb->format->format);
 558	u32 bg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR,
 559						    sb->format->format);
 560	const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
 561	struct drm_rect r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);
 562	struct kmsg_dump_iter iter;
 563	char kmsg_buf[512];
 564	size_t kmsg_len;
 565	struct drm_panic_line line;
 566	int yoffset;
 567
 568	if (!font || font->width > sb->width)
 569		return;
 570
 571	yoffset = sb->height - font->height - (sb->height % font->height) / 2;
 572
 573	/* Fill with the background color, and draw text on top */
 574	drm_panic_fill(sb, &r_screen, bg_color);
 575
 576	kmsg_dump_rewind(&iter);
 577	while (kmsg_dump_get_buffer(&iter, false, kmsg_buf, sizeof(kmsg_buf), &kmsg_len)) {
 578		char *start;
 579		char *end;
 580
 581		/* ignore terminating NUL and newline */
 582		start = kmsg_buf + kmsg_len - 2;
 583		end = kmsg_buf + kmsg_len - 1;
 584		while (start > kmsg_buf && yoffset >= 0) {
 585			while (start > kmsg_buf && *start != '\n')
 586				start--;
 587			/* don't count the newline character */
 588			line.txt = start + (start == kmsg_buf ? 0 : 1);
 589			line.len = end - line.txt;
 590
 591			yoffset = draw_line_with_wrap(sb, font, &line, yoffset, fg_color);
 592			end = start;
 593			start--;
 594		}
 595	}
 596}
 597
 598#if defined(CONFIG_DRM_PANIC_SCREEN_QR_CODE)
 599/*
 600 * It is unwise to allocate memory in the panic callback, so the buffers are
 601 * pre-allocated. Only 2 buffers and the zlib workspace are needed.
 602 * Two buffers are enough, using the following buffer usage:
 603 * 1) kmsg messages are dumped in buffer1
 604 * 2) kmsg is zlib-compressed into buffer2
 605 * 3) compressed kmsg is encoded as QR-code Numeric stream in buffer1
 606 * 4) QR-code image is generated in buffer2
 607 * The Max QR code size is V40, 177x177, 4071 bytes for image, 2956 bytes for
 608 * data segments.
 609 *
 610 * Typically, ~7500 bytes of kmsg, are compressed into 2800 bytes, which fits in
 611 * a V40 QR-code (177x177).
 612 *
 613 * If CONFIG_DRM_PANIC_SCREEN_QR_CODE_URL is not set, the kmsg data will be put
 614 * directly in the QR code.
 615 * 1) kmsg messages are dumped in buffer1
 616 * 2) kmsg message is encoded as byte stream in buffer2
 617 * 3) QR-code image is generated in buffer1
 618 */
 619
 620static uint panic_qr_version = CONFIG_DRM_PANIC_SCREEN_QR_VERSION;
 621module_param(panic_qr_version, uint, 0644);
 622MODULE_PARM_DESC(panic_qr_version, "maximum version (size) of the QR code");
 623
 624#define MAX_QR_DATA 2956
 625#define MAX_ZLIB_RATIO 3
 626#define QR_BUFFER1_SIZE (MAX_ZLIB_RATIO * MAX_QR_DATA) /* Must also be > 4071  */
 627#define QR_BUFFER2_SIZE 4096
 628#define QR_MARGIN	4	/* 4 modules of foreground color around the qr code */
 629
 630/* Compression parameters */
 631#define COMPR_LEVEL 6
 632#define WINDOW_BITS 12
 633#define MEM_LEVEL 4
 634
 635static char *qrbuf1;
 636static char *qrbuf2;
 637static struct z_stream_s stream;
 638
 639static void __init drm_panic_qr_init(void)
 640{
 641	qrbuf1 = kmalloc(QR_BUFFER1_SIZE, GFP_KERNEL);
 642	qrbuf2 = kmalloc(QR_BUFFER2_SIZE, GFP_KERNEL);
 643	stream.workspace = kmalloc(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
 644				   GFP_KERNEL);
 645}
 646
 647static void drm_panic_qr_exit(void)
 648{
 649	kfree(qrbuf1);
 650	qrbuf1 = NULL;
 651	kfree(qrbuf2);
 652	qrbuf2 = NULL;
 653	kfree(stream.workspace);
 654	stream.workspace = NULL;
 655}
 656
 657static int drm_panic_get_qr_code_url(u8 **qr_image)
 658{
 659	struct kmsg_dump_iter iter;
 660	char url[256];
 661	size_t kmsg_len, max_kmsg_size;
 662	char *kmsg;
 663	int max_qr_data_size, url_len;
 664
 665	url_len = snprintf(url, sizeof(url), CONFIG_DRM_PANIC_SCREEN_QR_CODE_URL "?a=%s&v=%s&z=",
 666			   utsname()->machine, utsname()->release);
 667
 668	max_qr_data_size = drm_panic_qr_max_data_size(panic_qr_version, url_len);
 669	max_kmsg_size = min(MAX_ZLIB_RATIO * max_qr_data_size, QR_BUFFER1_SIZE);
 670
 671	/* get kmsg to buffer 1 */
 672	kmsg_dump_rewind(&iter);
 673	kmsg_dump_get_buffer(&iter, false, qrbuf1, max_kmsg_size, &kmsg_len);
 674
 675	if (!kmsg_len)
 676		return -ENODATA;
 677	kmsg = qrbuf1;
 678
 679try_again:
 680	if (zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
 681			      MEM_LEVEL, Z_DEFAULT_STRATEGY) != Z_OK)
 682		return -EINVAL;
 683
 684	stream.next_in = kmsg;
 685	stream.avail_in = kmsg_len;
 686	stream.total_in = 0;
 687	stream.next_out = qrbuf2;
 688	stream.avail_out = QR_BUFFER2_SIZE;
 689	stream.total_out = 0;
 690
 691	if (zlib_deflate(&stream, Z_FINISH) != Z_STREAM_END)
 692		return -EINVAL;
 693
 694	if (zlib_deflateEnd(&stream) != Z_OK)
 695		return -EINVAL;
 696
 697	if (stream.total_out > max_qr_data_size) {
 698		/* too much data for the QR code, so skip the first line and try again */
 699		kmsg = strchr(kmsg, '\n');
 700		if (!kmsg)
 701			return -EINVAL;
 702		/* skip the first \n */
 703		kmsg += 1;
 704		kmsg_len = strlen(kmsg);
 705		goto try_again;
 706	}
 707	*qr_image = qrbuf2;
 708
 709	/* generate qr code image in buffer2 */
 710	return drm_panic_qr_generate(url, qrbuf2, stream.total_out, QR_BUFFER2_SIZE,
 711				     qrbuf1, QR_BUFFER1_SIZE);
 712}
 713
 714static int drm_panic_get_qr_code_raw(u8 **qr_image)
 715{
 716	struct kmsg_dump_iter iter;
 717	size_t kmsg_len;
 718	size_t max_kmsg_size = min(drm_panic_qr_max_data_size(panic_qr_version, 0),
 719				   QR_BUFFER1_SIZE);
 720
 721	kmsg_dump_rewind(&iter);
 722	kmsg_dump_get_buffer(&iter, false, qrbuf1, max_kmsg_size, &kmsg_len);
 723	if (!kmsg_len)
 724		return -ENODATA;
 725
 726	*qr_image = qrbuf1;
 727	return drm_panic_qr_generate(NULL, qrbuf1, kmsg_len, QR_BUFFER1_SIZE,
 728				     qrbuf2, QR_BUFFER2_SIZE);
 729}
 730
 731static int drm_panic_get_qr_code(u8 **qr_image)
 732{
 733	if (strlen(CONFIG_DRM_PANIC_SCREEN_QR_CODE_URL) > 0)
 734		return drm_panic_get_qr_code_url(qr_image);
 735	else
 736		return drm_panic_get_qr_code_raw(qr_image);
 737}
 738
 739/*
 740 * Draw the panic message at the center of the screen, with a QR Code
 741 */
 742static int _draw_panic_static_qr_code(struct drm_scanout_buffer *sb)
 743{
 744	u32 fg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR,
 745						    sb->format->format);
 746	u32 bg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR,
 747						    sb->format->format);
 748	const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
 749	struct drm_rect r_screen, r_logo, r_msg, r_qr, r_qr_canvas;
 750	unsigned int max_qr_size, scale;
 751	unsigned int msg_width, msg_height;
 752	int qr_width, qr_canvas_width, qr_pitch, v_margin;
 753	u8 *qr_image;
 754
 755	if (!font || !qrbuf1 || !qrbuf2 || !stream.workspace)
 756		return -ENOMEM;
 757
 758	r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);
 759
 760	drm_panic_logo_rect(&r_logo, font);
 761
 762	msg_width = min(get_max_line_len(panic_msg, panic_msg_lines) * font->width, sb->width);
 763	msg_height = min(panic_msg_lines * font->height, sb->height);
 764	r_msg = DRM_RECT_INIT(0, 0, msg_width, msg_height);
 765
 766	max_qr_size = min(3 * sb->width / 4, 3 * sb->height / 4);
 767
 768	qr_width = drm_panic_get_qr_code(&qr_image);
 769	if (qr_width <= 0)
 770		return -ENOSPC;
 771
 772	qr_canvas_width = qr_width + QR_MARGIN * 2;
 773	scale = max_qr_size / qr_canvas_width;
 774	/* QR code is not readable if not scaled at least by 2 */
 775	if (scale < 2)
 776		return -ENOSPC;
 777
 778	pr_debug("QR width %d and scale %d\n", qr_width, scale);
 779	r_qr_canvas = DRM_RECT_INIT(0, 0, qr_canvas_width * scale, qr_canvas_width * scale);
 780
 781	v_margin = sb->height - drm_rect_height(&r_qr_canvas) - drm_rect_height(&r_msg);
 782	if (v_margin < 0)
 783		return -ENOSPC;
 784	v_margin /= 5;
 785
 786	drm_rect_translate(&r_qr_canvas, (sb->width - r_qr_canvas.x2) / 2, 2 * v_margin);
 787	r_qr = DRM_RECT_INIT(r_qr_canvas.x1 + QR_MARGIN * scale, r_qr_canvas.y1 + QR_MARGIN * scale,
 788			     qr_width * scale, qr_width * scale);
 789
 790	/* Center the panic message */
 791	drm_rect_translate(&r_msg, (sb->width - r_msg.x2) / 2,
 792			   3 * v_margin + drm_rect_height(&r_qr_canvas));
 793
 794	/* Fill with the background color, and draw text on top */
 795	drm_panic_fill(sb, &r_screen, bg_color);
 796
 797	if (!drm_rect_overlap(&r_logo, &r_msg) && !drm_rect_overlap(&r_logo, &r_qr_canvas))
 798		drm_panic_logo_draw(sb, &r_logo, font, fg_color);
 799
 800	draw_txt_rectangle(sb, font, panic_msg, panic_msg_lines, true, &r_msg, fg_color);
 801
 802	/* Draw the qr code */
 803	qr_pitch = DIV_ROUND_UP(qr_width, 8);
 804	drm_panic_fill(sb, &r_qr_canvas, fg_color);
 805	drm_panic_fill(sb, &r_qr, bg_color);
 806	drm_panic_blit(sb, &r_qr, qr_image, qr_pitch, scale, fg_color);
 807	return 0;
 808}
 809
 810static void draw_panic_static_qr_code(struct drm_scanout_buffer *sb)
 811{
 812	if (_draw_panic_static_qr_code(sb))
 813		draw_panic_static_user(sb);
 814}
 815#else
 816static void draw_panic_static_qr_code(struct drm_scanout_buffer *sb)
 817{
 818	draw_panic_static_user(sb);
 819}
 820
 821static void drm_panic_qr_init(void) {};
 822static void drm_panic_qr_exit(void) {};
 823#endif
 824
 825/*
 826 * drm_panic_is_format_supported()
 827 * @format: a fourcc color code
 828 * Returns: true if supported, false otherwise.
 829 *
 830 * Check if drm_panic will be able to use this color format.
 831 */
 832static bool drm_panic_is_format_supported(const struct drm_format_info *format)
 833{
 834	if (format->num_planes != 1)
 835		return false;
 836	return drm_draw_color_from_xrgb8888(0xffffff, format->format) != 0;
 837}
 838
 839static void draw_panic_dispatch(struct drm_scanout_buffer *sb)
 840{
 841	if (!strcmp(drm_panic_screen, "kmsg")) {
 842		draw_panic_static_kmsg(sb);
 843	} else if (!strcmp(drm_panic_screen, "qr_code")) {
 844		draw_panic_static_qr_code(sb);
 845	} else {
 846		draw_panic_static_user(sb);
 847	}
 848}
 849
 850static void drm_panic_set_description(const char *description)
 851{
 852	u32 len;
 853
 854	if (description) {
 855		struct drm_panic_line *desc_line = &panic_msg[panic_msg_lines - 1];
 856
 857		desc_line->txt = description;
 858		len = strlen(description);
 859		/* ignore the last newline character */
 860		if (len && description[len - 1] == '\n')
 861			len -= 1;
 862		desc_line->len = len;
 863	}
 864}
 865
 866static void drm_panic_clear_description(void)
 867{
 868	struct drm_panic_line *desc_line = &panic_msg[panic_msg_lines - 1];
 869
 870	desc_line->len = 0;
 871	desc_line->txt = NULL;
 872}
 873
 874static void draw_panic_plane(struct drm_plane *plane, const char *description)
 875{
 876	struct drm_scanout_buffer sb = { };
 877	int ret;
 878	unsigned long flags;
 879
 880	if (!drm_panic_trylock(plane->dev, flags))
 881		return;
 882
 883	ret = plane->helper_private->get_scanout_buffer(plane, &sb);
 884
 885	if (ret || !drm_panic_is_format_supported(sb.format))
 886		goto unlock;
 887
 888	/* One of these should be set, or it can't draw pixels */
 889	if (!sb.set_pixel && !sb.pages && iosys_map_is_null(&sb.map[0]))
 890		goto unlock;
 891
 892	drm_panic_set_description(description);
 893
 894	draw_panic_dispatch(&sb);
 895	if (plane->helper_private->panic_flush)
 896		plane->helper_private->panic_flush(plane);
 897
 898	drm_panic_clear_description();
 899
 900unlock:
 901	drm_panic_unlock(plane->dev, flags);
 902}
 903
 904static struct drm_plane *to_drm_plane(struct kmsg_dumper *kd)
 905{
 906	return container_of(kd, struct drm_plane, kmsg_panic);
 907}
 908
 909static void drm_panic(struct kmsg_dumper *dumper, struct kmsg_dump_detail *detail)
 910{
 911	struct drm_plane *plane = to_drm_plane(dumper);
 912
 913	if (detail->reason == KMSG_DUMP_PANIC)
 914		draw_panic_plane(plane, detail->description);
 915}
 916
 917
 918/*
 919 * DEBUG FS, This is currently unsafe.
 920 * Create one file per plane, so it's possible to debug one plane at a time.
 921 * TODO: It would be better to emulate an NMI context.
 922 */
 923#ifdef CONFIG_DRM_PANIC_DEBUG
 924#include <linux/debugfs.h>
 925
 926static ssize_t debugfs_trigger_write(struct file *file, const char __user *user_buf,
 927				     size_t count, loff_t *ppos)
 928{
 929	bool run;
 930
 931	if (kstrtobool_from_user(user_buf, count, &run) == 0 && run) {
 932		struct drm_plane *plane = file->private_data;
 933
 934		draw_panic_plane(plane, "Test from debugfs");
 935	}
 936	return count;
 937}
 938
 939static const struct file_operations dbg_drm_panic_ops = {
 940	.owner = THIS_MODULE,
 941	.write = debugfs_trigger_write,
 942	.open = simple_open,
 943};
 944
 945static void debugfs_register_plane(struct drm_plane *plane, int index)
 946{
 947	char fname[32];
 948
 949	snprintf(fname, 32, "drm_panic_plane_%d", index);
 950	debugfs_create_file(fname, 0200, plane->dev->debugfs_root,
 951			    plane, &dbg_drm_panic_ops);
 952}
 953#else
 954static void debugfs_register_plane(struct drm_plane *plane, int index) {}
 955#endif /* CONFIG_DRM_PANIC_DEBUG */
 956
 957/**
 958 * drm_panic_is_enabled
 959 * @dev: the drm device that may supports drm_panic
 960 *
 961 * returns true if the drm device supports drm_panic
 962 */
 963bool drm_panic_is_enabled(struct drm_device *dev)
 964{
 965	struct drm_plane *plane;
 966
 967	if (!dev->mode_config.num_total_plane)
 968		return false;
 969
 970	drm_for_each_plane(plane, dev)
 971		if (plane->helper_private && plane->helper_private->get_scanout_buffer)
 972			return true;
 973	return false;
 974}
 975EXPORT_SYMBOL(drm_panic_is_enabled);
 976
 977/**
 978 * drm_panic_register() - Initialize DRM panic for a device
 979 * @dev: the drm device on which the panic screen will be displayed.
 980 */
 981void drm_panic_register(struct drm_device *dev)
 982{
 983	struct drm_plane *plane;
 984	int registered_plane = 0;
 985
 986	if (!dev->mode_config.num_total_plane)
 987		return;
 988
 989	drm_for_each_plane(plane, dev) {
 990		if (!plane->helper_private || !plane->helper_private->get_scanout_buffer)
 991			continue;
 992		plane->kmsg_panic.dump = drm_panic;
 993		plane->kmsg_panic.max_reason = KMSG_DUMP_PANIC;
 994		if (kmsg_dump_register(&plane->kmsg_panic))
 995			drm_warn(dev, "Failed to register panic handler\n");
 996		else {
 997			debugfs_register_plane(plane, registered_plane);
 998			registered_plane++;
 999		}
1000	}
1001	if (registered_plane)
1002		drm_info(dev, "Registered %d planes with drm panic\n", registered_plane);
1003}
1004
1005/**
1006 * drm_panic_unregister()
1007 * @dev: the drm device previously registered.
1008 */
1009void drm_panic_unregister(struct drm_device *dev)
1010{
1011	struct drm_plane *plane;
1012
1013	if (!dev->mode_config.num_total_plane)
1014		return;
1015
1016	drm_for_each_plane(plane, dev) {
1017		if (!plane->helper_private || !plane->helper_private->get_scanout_buffer)
1018			continue;
1019		kmsg_dump_unregister(&plane->kmsg_panic);
1020	}
1021}
1022
1023/**
1024 * drm_panic_init() - initialize DRM panic.
1025 */
1026void __init drm_panic_init(void)
1027{
1028	drm_panic_qr_init();
1029}
1030
1031/**
1032 * drm_panic_exit() - Free the resources taken by drm_panic_exit()
1033 */
1034void drm_panic_exit(void)
1035{
1036	drm_panic_qr_exit();
1037}