This module displays a user friendly message when a kernel panic occurs. It currently doesn't contain any debug information, but that can be added later. Signed-off-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx> --- drivers/gpu/drm/Kconfig | 11 ++ drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/drm_drv.c | 3 + drivers/gpu/drm/drm_panic.c | 286 ++++++++++++++++++++++++++++++++++++ include/drm/drm_panic.h | 26 ++++ 5 files changed, 327 insertions(+) create mode 100644 drivers/gpu/drm/drm_panic.c create mode 100644 include/drm/drm_panic.h diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index ba3fb04bb691..cc6771351d6d 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -98,6 +98,17 @@ config DRM_KMS_HELPER help CRTC helpers for KMS drivers. +config DRM_PANIC + bool "Display a user-friendly message when a kernel panic occurs" + depends on DRM && !FRAMEBUFFER_CONSOLE + select FONT_SUPPORT + default y if DRM_SIMPLEDRM + help + Enable a drm panic handler, which will display a user-friendly message + when a kernel panic occurs. It's useful when using a user-space + console instead of fbcon. + It will only work if your graphic driver supports this feature. + config DRM_DEBUG_DP_MST_TOPOLOGY_REFS bool "Enable refcount backtrace history in the DP MST helpers" depends on STACKTRACE_SUPPORT diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index a33257d2bc7f..c73dbac9c01e 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -72,6 +72,7 @@ drm-$(CONFIG_DRM_PRIVACY_SCREEN) += \ drm_privacy_screen_x86.o drm-$(CONFIG_DRM_ACCEL) += ../../accel/drm_accel.o obj-$(CONFIG_DRM) += drm.o +drm-$(CONFIG_DRM_PANIC) += drm_panic.o obj-$(CONFIG_DRM_PANEL_ORIENTATION_QUIRKS) += drm_panel_orientation_quirks.o diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index cee0cc522ed9..0f2d96edd86d 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -45,6 +45,7 @@ #include <drm/drm_mode_object.h> #include <drm/drm_print.h> #include <drm/drm_privacy_screen_machine.h> +#include <drm/drm_panic.h> #include "drm_crtc_internal.h" #include "drm_internal.h" @@ -1065,6 +1066,7 @@ static void drm_core_exit(void) unregister_chrdev(DRM_MAJOR, "drm"); debugfs_remove(drm_debugfs_root); drm_sysfs_destroy(); + drm_panic_exit(); idr_destroy(&drm_minors_idr); drm_connector_ida_destroy(); } @@ -1076,6 +1078,7 @@ static int __init drm_core_init(void) drm_connector_ida_init(); idr_init(&drm_minors_idr); drm_memcpy_init_early(); + drm_panic_init(); ret = drm_sysfs_init(); if (ret < 0) { diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c new file mode 100644 index 000000000000..538ca5daaebf --- /dev/null +++ b/drivers/gpu/drm/drm_panic.c @@ -0,0 +1,286 @@ +// SPDX-License-Identifier: GPL-2.0 or MIT +/* + * Copyright (c) 2023 Jocelyn Falempe <jfalempe@xxxxxxxxxx> + * inspired by the drm_log driver from David Herrmann <dh.herrmann@xxxxxxxxx> + * Tux Ascii art taken from cowsay written by Tony Monroe + */ + +#include <linux/font.h> +#include <linux/iosys-map.h> +#include <linux/kdebug.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/panic_notifier.h> +#include <linux/types.h> +#include <linux/slab.h> + +#include <drm/drm_client.h> +#include <drm/drm_fourcc.h> +#include <drm/drm_framebuffer.h> +#include <drm/drm_print.h> + +MODULE_AUTHOR("Jocelyn Falempe"); +MODULE_DESCRIPTION("DRM PANIC"); +MODULE_LICENSE("GPL"); + +/** + * This module displays a user friendly message on screen when a kernel panic + * occurs. + * It will display only one frame, so just clear it, and draw white pixels for + * the characters. Performance optimizations are low priority as the machine is + * already in an unusable state. + */ + +/** + * List of drm clients + */ +struct dpanic_drm_client { + struct list_head head; + struct drm_client_dev client; +}; + +struct dpanic_line { + u32 len; + const char *txt; +}; + +#define PANIC_LINE(s) {.len = sizeof(s), .txt = s} + +const struct dpanic_line panic_msg[] = { + PANIC_LINE("KERNEL PANIC !"), + PANIC_LINE(""), + PANIC_LINE("Please reboot your computer.") +}; + +const struct dpanic_line logo[] = { + PANIC_LINE(" .--."), + PANIC_LINE(" |o_o |"), + PANIC_LINE(" |:_/ |"), + PANIC_LINE(" // \\ \\"), + PANIC_LINE(" (| | )"), + PANIC_LINE(" /'\\_ _/`\\"), + PANIC_LINE(" \\___)=(___/"), +}; + +static LIST_HEAD(dpanic_clients); +static DEFINE_MUTEX(dpanic_lock); + +#define IOSYS_WRITE8(offset, val) iosys_map_wr(screen_base, offset, u8, val) +/* + * Only handle DRM_FORMAT_XRGB8888 for testing + */ +static inline void dpanic_draw_px(struct iosys_map *screen_base, size_t offset, u32 pixel_format, + u8 r, u8 g, u8 b) +{ + switch (pixel_format) { + case DRM_FORMAT_XRGB8888: + IOSYS_WRITE8(offset++, b); + IOSYS_WRITE8(offset++, g); + IOSYS_WRITE8(offset++, r); + IOSYS_WRITE8(offset++, 0xff); + break; + default: + pr_err("Format not supported\n"); + break; + /* TODO other format */ + } +} + +/* Draw a single character at given destination */ +static void dpanic_draw_char(char ch, size_t x, size_t y, + struct drm_framebuffer *fb, + struct iosys_map *map, + const struct font_desc *font) +{ + size_t src_width, src_height, src_stride, i, dst_off; + const u8 *src; + + src_width = font->width; + src_height = font->height; + src_stride = DIV_ROUND_UP(src_width, 8); + + dst_off = x * font->width * fb->format->cpp[0] + y * font->height * fb->pitches[0]; + + src = font->data; + src += ch * src_height * src_stride; + + while (src_height--) { + for (i = 0; i < src_width; ++i) { + /* only draw white pixels */ + if (src[i / 8] & (0x80 >> (i % 8))) + dpanic_draw_px(map, dst_off + i * fb->format->cpp[0], + fb->format->format, 0xff, 0xff, 0xff); + } + src += src_stride; + dst_off += fb->pitches[0]; + } +} + +static void dpanic_draw_line_centered(const struct dpanic_line *line, size_t y, + struct drm_framebuffer *fb, + struct iosys_map *map, + const struct font_desc *font) +{ + size_t chars_per_line = fb->width / font->width; + size_t skip_left, x; + + if (line->len > chars_per_line) + return; + + skip_left = (chars_per_line - line->len) / 2; + + for (x = 0; x < line->len; x++) + dpanic_draw_char(line->txt[x], skip_left + x, y, fb, map, font); +} + +/* + * Draw the Tux logo at the upper left corner + */ +static void dpanic_draw_logo(struct drm_framebuffer *fb, + struct iosys_map *map, + const struct font_desc *font) +{ + size_t chars_per_line = fb->width / font->width; + size_t x, y; + + for (y = 0; y < ARRAY_SIZE(logo); y++) + for (x = 0; x < logo[y].len && x < chars_per_line; x++) + dpanic_draw_char(logo[y].txt[x], x, y, fb, map, font); +} + +/* + * Draw the panic message at the center of the screen + */ +static void dpanic_static_draw(struct drm_client_buffer *buffer) +{ + size_t y, lines, skip_top; + size_t len = ARRAY_SIZE(panic_msg); + struct iosys_map map; + struct drm_framebuffer *fb = buffer->fb; + const struct font_desc *font = get_default_font(fb->width, fb->height, 0x8080, 0x8080); + + if (!font) + return; + + if (drm_client_buffer_vmap(buffer, &map)) { + pr_err("VMAP failed\n"); + return; + } + lines = fb->height / font->height; + skip_top = (lines - len) / 2; + + /* clear screen */ + iosys_map_memset(&map, 0, 0, fb->height * fb->pitches[0]); + + for (y = 0; y < len; y++) + dpanic_draw_line_centered(&panic_msg[y], y + skip_top, fb, &map, font); + + if (skip_top >= ARRAY_SIZE(logo)) + dpanic_draw_logo(fb, &map, font); + + drm_client_framebuffer_flush(buffer, NULL); +} + +#define MAX_MODESET 8 + +static void drm_panic_client(struct drm_client_dev *client) +{ + struct drm_client_buffer *buffer[MAX_MODESET]; + int ret, n_modeset, i; + struct drm_mode_set *mode_set; + + ret = drm_client_modeset_probe(client, 0, 0); + if (ret) + return; + + n_modeset = 0; + drm_client_for_each_modeset(mode_set, client) { + struct drm_plane *primary = mode_set->crtc->primary; + struct drm_framebuffer *fb; + + if (primary->state && primary->state->fb) + fb = primary->state->fb; + else if (primary->fb) + fb = primary->fb; + else + continue; + + pr_debug("DRM Panic, FB width %d, height %d\n", fb->width, fb->height); + buffer[n_modeset] = drm_client_framebuffer_create(client, fb->width, + fb->height, + fb->format->format); + + if (IS_ERR(buffer[n_modeset])) { + pr_err("DRM Panic can't allocate buffer\n"); + continue; + } + mode_set->fb = buffer[n_modeset]->fb; + n_modeset++; + if (n_modeset == MAX_MODESET) + break; + } + ret = drm_client_modeset_commit_locked(client); + if (ret) + return; + + for (i = 0; i < n_modeset; i++) + dpanic_static_draw(buffer[i]); +} + +static int drm_panic(struct notifier_block *this, unsigned long event, + void *ptr) +{ + struct dpanic_drm_client *dpanic_client; + + list_for_each_entry(dpanic_client, &dpanic_clients, head) { + drm_panic_client(&dpanic_client->client); + } + return NOTIFY_OK; +} + +struct notifier_block drm_panic_notifier = { + .notifier_call = drm_panic, +}; + +void drm_panic_init_client(struct drm_device *dev) +{ + struct dpanic_drm_client *new; + int ret; + + new = kzalloc(sizeof(*new), GFP_KERNEL); + if (!new) + return; + + ret = drm_client_init(dev, &new->client, "drm_panic", NULL); + if (ret < 0) { + kfree(new); + return; + } + drm_client_register(&new->client); + list_add_tail(&new->head, &dpanic_clients); + + drm_info(dev, "Registered with drm panic\n"); +} +EXPORT_SYMBOL(drm_panic_init_client); + +/** + * drm_panic_init() - Initialize drm-panic subsystem + * + * register the panic notifier + */ +void drm_panic_init(void) +{ + /* register panic handler */ + atomic_notifier_chain_register(&panic_notifier_list, + &drm_panic_notifier); +} + +/** + * drm_log_exit() - Shutdown drm-panic subsystem + */ +void drm_panic_exit(void) +{ + atomic_notifier_chain_unregister(&panic_notifier_list, + &drm_panic_notifier); +} diff --git a/include/drm/drm_panic.h b/include/drm/drm_panic.h new file mode 100644 index 000000000000..a943b82324e3 --- /dev/null +++ b/include/drm/drm_panic.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0 or MIT */ +#ifndef __DRM_PANIC_H__ +#define __DRM_PANIC_H__ + +/* + * Copyright (c) 2023 Jocelyn Falempe <jfalempe@xxxxxxxxxx> + */ + +#include <linux/module.h> +#include <linux/types.h> +#include <linux/iosys-map.h> + +#ifdef CONFIG_DRM_PANIC + +void drm_panic_init(void); +void drm_panic_exit(void); + +void drm_panic_init_client(struct drm_device *dev); +#else + +static inline void drm_panic_init(void) {} +static inline void drm_panic_exit(void) {} +static inline void drm_panic_init_client(struct drm_device *dev) {} +#endif + +#endif /* __DRM_LOG_H__ */ -- 2.41.0