From bf9fb17c6672868d95126321762c8fdfe0ff0a2a Mon Sep 17 00:00:00 2001 From: Jocelyn Falempe Date: Tue, 9 Apr 2024 18:30:41 +0200 Subject: drm/panic: Add a drm panic handler 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. v2 * Use get_scanout_buffer() instead of the drm client API. (Thomas Zimmermann) * Add the panic reason to the panic message (Nerdopolis) * Add an exclamation mark (Nerdopolis) v3 * Rework the drawing functions, to write the pixels line by line and to use the drm conversion helper to support other formats. (Thomas Zimmermann) v4 * Use drm_fb_r1_to_32bit for fonts (Thomas Zimmermann) * Remove the default y to DRM_PANIC config option (Thomas Zimmermann) * Add foreground/background color config option * Fix the bottom lines not painted if the framebuffer height is not a multiple of the font height. * Automatically register the device to drm_panic, if the function get_scanout_buffer exists. (Thomas Zimmermann) v5 * Change the drawing API, use drm_fb_blit_from_r1() to draw the font. * Also add drm_fb_fill() to fill area with background color. * Add draw_pixel_xy() API for drivers that can't provide a linear buffer. * Add a flush() callback for drivers that needs to synchronize the buffer. * Add a void *private field, so drivers can pass private data to draw_pixel_xy() and flush(). v6 * Fix sparse warning for panic_msg and logo. v7 * Add select DRM_KMS_HELPER for the color conversion functions. v8 * Register directly each plane to the panic notifier (Sima) * Add raw_spinlock to properly handle concurrency (Sima) * Register plane instead of device, to avoid looping through plane list, and simplify code. * Replace get_scanout_buffer() logic with drm_panic_set_buffer() (Thomas Zimmermann) * Removed the draw_pixel_xy() API, will see later if it can be added back. v9 * Revert to using get_scanout_buffer() (Sima) * Move get_scanout_buffer() and panic_flush() to the plane helper functions (Thomas Zimmermann) * Register all planes with get_scanout_buffer() to the panic notifier * Use drm_panic_lock() to protect against race (Sima) v10 * Move blit and fill functions back in drm_panic (Thomas Zimmermann). * Simplify the text drawing functions. * Use kmsg_dumper instead of panic_notifier (Sima). v12 * Use array for map and pitch in struct drm_scanout_buffer to support multi-planar format later. (Thomas Zimmermann) * Better indent struct drm_scanout_buffer declaration. (Thomas Zimmermann) Signed-off-by: Jocelyn Falempe Link: https://patchwork.freedesktop.org/patch/msgid/20240409163432.352518-3-jfalempe@redhat.com Acked-by: Daniel Vetter --- Documentation/gpu/drm-kms.rst | 15 ++ drivers/gpu/drm/Kconfig | 23 +++ drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/drm_drv.c | 4 + drivers/gpu/drm/drm_panic.c | 290 +++++++++++++++++++++++++++++++ include/drm/drm_modeset_helper_vtables.h | 39 +++++ include/drm/drm_panic.h | 57 ++++++ include/drm/drm_plane.h | 6 + 8 files changed, 435 insertions(+) create mode 100644 drivers/gpu/drm/drm_panic.c diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst index b98b98359c90..abfe220764e1 100644 --- a/Documentation/gpu/drm-kms.rst +++ b/Documentation/gpu/drm-kms.rst @@ -398,6 +398,21 @@ Plane Damage Tracking Functions Reference .. kernel-doc:: include/drm/drm_damage_helper.h :internal: +Plane Panic Feature +------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_panic.c + :doc: overview + +Plane Panic Functions Reference +------------------------------- + +.. kernel-doc:: include/drm/drm_panic.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_panic.c + :export: + Display Modes Function Reference ================================ diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index 3914aaf443a8..f8a26423369e 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -104,6 +104,29 @@ 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 DRM_KMS_HELPER + select FONT_SUPPORT + 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. + To support Hi-DPI Display, you can enable bigger fonts like + FONT_TER16x32 + +config DRM_PANIC_FOREGROUND_COLOR + hex "Drm panic screen foreground color, in RGB" + depends on DRM_PANIC + default 0xffffff + +config DRM_PANIC_BACKGROUND_COLOR + hex "Drm panic screen background color, in RGB" + depends on DRM_PANIC + default 0x000000 + 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 a73c04d2d7a3..f9ca4f8fa6c5 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -88,6 +88,7 @@ drm-$(CONFIG_DRM_PRIVACY_SCREEN) += \ drm_privacy_screen.o \ drm_privacy_screen_x86.o drm-$(CONFIG_DRM_ACCEL) += ../../accel/drm_accel.o +drm-$(CONFIG_DRM_PANIC) += drm_panic.o obj-$(CONFIG_DRM) += drm.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 c157500b3135..535b624d4c9d 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -43,6 +43,7 @@ #include #include #include +#include #include #include @@ -944,6 +945,7 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags) if (ret) goto err_unload; } + drm_panic_register(dev); DRM_INFO("Initialized %s %d.%d.%d %s for %s on minor %d\n", driver->name, driver->major, driver->minor, @@ -988,6 +990,8 @@ void drm_dev_unregister(struct drm_device *dev) { dev->registered = false; + drm_panic_unregister(dev); + drm_client_dev_unregister(dev); if (drm_core_check_feature(dev, DRIVER_MODESET)) diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c new file mode 100644 index 000000000000..7c81b3d73239 --- /dev/null +++ b/drivers/gpu/drm/drm_panic.c @@ -0,0 +1,290 @@ +// SPDX-License-Identifier: GPL-2.0 or MIT +/* + * Copyright (c) 2023 Red Hat. + * Author: Jocelyn Falempe + * inspired by the drm_log driver from David Herrmann + * Tux Ascii art taken from cowsay written by Tony Monroe + */ + +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include + +MODULE_AUTHOR("Jocelyn Falempe"); +MODULE_DESCRIPTION("DRM panic handler"); +MODULE_LICENSE("GPL"); + +/** + * DOC: overview + * + * To enable DRM panic for a driver, the primary plane must implement a + * &drm_plane_helper_funcs.get_scanout_buffer helper function. It is then + * automatically registered to the drm panic handler. + * When a panic occurs, the &drm_plane_helper_funcs.get_scanout_buffer will be + * called, and the driver can provide a framebuffer so the panic handler can + * draw the panic screen on it. Currently only linear buffer and a few color + * formats are supported. + * Optionally the driver can also provide a &drm_plane_helper_funcs.panic_flush + * callback, that will be called after that, to send additional commands to the + * hardware to make the scanout buffer visible. + */ + +/* + * This module displays a user friendly message on screen when a kernel panic + * occurs. This is conflicting with fbcon, so you can only enable it when fbcon + * is disabled. + * It's intended for end-user, so have minimal technical/debug information. + * + * Implementation details: + * + * It is a panic handler, so it can't take lock, allocate memory, run tasks/irq, + * or attempt to sleep. It's a best effort, and it may not be able to display + * the message in all situations (like if the panic occurs in the middle of a + * modesetting). + * It will display only one static frame, so performance optimizations are low + * priority as the machine is already in an unusable state. + */ + +struct drm_panic_line { + u32 len; + const char *txt; +}; + +#define PANIC_LINE(s) {.len = sizeof(s) - 1, .txt = s} + +static struct drm_panic_line panic_msg[] = { + PANIC_LINE("KERNEL PANIC !"), + PANIC_LINE(""), + PANIC_LINE("Please reboot your computer."), +}; + +static const struct drm_panic_line logo[] = { + PANIC_LINE(" .--. _"), + PANIC_LINE(" |o_o | | |"), + PANIC_LINE(" |:_/ | | |"), + PANIC_LINE(" // \\ \\ |_|"), + PANIC_LINE(" (| | ) _"), + PANIC_LINE(" /'\\_ _/`\\ (_)"), + PANIC_LINE(" \\___)=(___/"), +}; + +static void drm_panic_fill32(struct iosys_map *map, unsigned int pitch, + unsigned int height, unsigned int width, + u32 color) +{ + unsigned int y, x; + + for (y = 0; y < height; y++) + for (x = 0; x < width; x++) + iosys_map_wr(map, y * pitch + x * sizeof(u32), u32, color); +} + +static void drm_panic_blit32(struct iosys_map *dmap, unsigned int dpitch, + const u8 *sbuf8, unsigned int spitch, + unsigned int height, unsigned int width, + u32 fg32, u32 bg32) +{ + unsigned int y, x; + u32 val32; + + for (y = 0; y < height; y++) { + for (x = 0; x < width; x++) { + val32 = (sbuf8[(y * spitch) + x / 8] & (0x80 >> (x % 8))) ? fg32 : bg32; + iosys_map_wr(dmap, y * dpitch + x * sizeof(u32), u32, val32); + } + } +} + +static const u8 *get_char_bitmap(const struct font_desc *font, char c, size_t font_pitch) +{ + return font->data + (c * font->height) * font_pitch; +} + +static unsigned int get_max_line_len(const struct drm_panic_line *lines, int len) +{ + int i; + unsigned int max = 0; + + for (i = 0; i < len; i++) + max = max(lines[i].len, max); + return max; +} + +/* + * Draw a text in a rectangle on a framebuffer. The text is truncated if it overflows the rectangle + */ +static void draw_txt_rectangle(struct drm_scanout_buffer *sb, + const struct font_desc *font, + const struct drm_panic_line *msg, + unsigned int msg_lines, + bool centered, + struct drm_rect *clip, + u32 fg_color, + u32 bg_color) +{ + int i, j; + const u8 *src; + size_t font_pitch = DIV_ROUND_UP(font->width, 8); + struct iosys_map dst; + unsigned int px_width = sb->format->cpp[0]; + int left = 0; + + msg_lines = min(msg_lines, drm_rect_height(clip) / font->height); + for (i = 0; i < msg_lines; i++) { + size_t line_len = min(msg[i].len, drm_rect_width(clip) / font->width); + + if (centered) + left = (drm_rect_width(clip) - (line_len * font->width)) / 2; + + dst = sb->map[0]; + iosys_map_incr(&dst, (clip->y1 + i * font->height) * sb->pitch[0] + + (clip->x1 + left) * px_width); + for (j = 0; j < line_len; j++) { + src = get_char_bitmap(font, msg[i].txt[j], font_pitch); + drm_panic_blit32(&dst, sb->pitch[0], src, font_pitch, + font->height, font->width, + fg_color, bg_color); + iosys_map_incr(&dst, font->width * px_width); + } + } +} + +/* + * Draw the panic message at the center of the screen + */ +static void draw_panic_static(struct drm_scanout_buffer *sb) +{ + size_t msg_lines = ARRAY_SIZE(panic_msg); + size_t logo_lines = ARRAY_SIZE(logo); + u32 fg_color = CONFIG_DRM_PANIC_FOREGROUND_COLOR; + u32 bg_color = CONFIG_DRM_PANIC_BACKGROUND_COLOR; + const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL); + struct drm_rect r_logo, r_msg; + + if (!font) + return; + + r_logo = DRM_RECT_INIT(0, 0, + get_max_line_len(logo, logo_lines) * font->width, + logo_lines * font->height); + r_msg = DRM_RECT_INIT(0, 0, + min(get_max_line_len(panic_msg, msg_lines) * font->width, sb->width), + min(msg_lines * font->height, sb->height)); + + /* Center the panic message */ + drm_rect_translate(&r_msg, (sb->width - r_msg.x2) / 2, (sb->height - r_msg.y2) / 2); + + /* Fill with the background color, and draw text on top */ + drm_panic_fill32(&sb->map[0], sb->pitch[0], sb->height, sb->width, bg_color); + + if ((r_msg.x1 >= drm_rect_width(&r_logo) || r_msg.y1 >= drm_rect_height(&r_logo)) && + drm_rect_width(&r_logo) < sb->width && drm_rect_height(&r_logo) < sb->height) { + draw_txt_rectangle(sb, font, logo, logo_lines, false, &r_logo, fg_color, bg_color); + } + draw_txt_rectangle(sb, font, panic_msg, msg_lines, true, &r_msg, fg_color, bg_color); +} + +/* + * drm_panic_is_format_supported() + * @format: a fourcc color code + * Returns: true if supported, false otherwise. + * + * Check if drm_panic will be able to use this color format. + */ +static bool drm_panic_is_format_supported(const struct drm_format_info *format) +{ + if (format->num_planes != 1) + return false; + return format->format == DRM_FORMAT_XRGB8888; +} + +static void draw_panic_plane(struct drm_plane *plane) +{ + struct drm_scanout_buffer sb; + int ret; + unsigned long flags; + + if (!drm_panic_trylock(plane->dev, flags)) + return; + + ret = plane->helper_private->get_scanout_buffer(plane, &sb); + + if (!ret && drm_panic_is_format_supported(sb.format)) { + draw_panic_static(&sb); + if (plane->helper_private->panic_flush) + plane->helper_private->panic_flush(plane); + } + drm_panic_unlock(plane->dev, flags); +} + +static struct drm_plane *to_drm_plane(struct kmsg_dumper *kd) +{ + return container_of(kd, struct drm_plane, kmsg_panic); +} + +static void drm_panic(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason) +{ + struct drm_plane *plane = to_drm_plane(dumper); + + if (reason == KMSG_DUMP_PANIC) + draw_panic_plane(plane); +} + +/** + * drm_panic_register() - Initialize DRM panic for a device + * @dev: the drm device on which the panic screen will be displayed. + */ +void drm_panic_register(struct drm_device *dev) +{ + struct drm_plane *plane; + int registered_plane = 0; + + if (!dev->mode_config.num_total_plane) + return; + + drm_for_each_plane(plane, dev) { + if (!plane->helper_private || !plane->helper_private->get_scanout_buffer) + continue; + plane->kmsg_panic.dump = drm_panic; + plane->kmsg_panic.max_reason = KMSG_DUMP_PANIC; + if (kmsg_dump_register(&plane->kmsg_panic)) + drm_warn(dev, "Failed to register panic handler\n"); + else + registered_plane++; + } + if (registered_plane) + drm_info(dev, "Registered %d planes with drm panic\n", registered_plane); +} +EXPORT_SYMBOL(drm_panic_register); + +/** + * drm_panic_unregister() + * @dev: the drm device previously registered. + */ +void drm_panic_unregister(struct drm_device *dev) +{ + struct drm_plane *plane; + + if (!dev->mode_config.num_total_plane) + return; + + drm_for_each_plane(plane, dev) { + if (!plane->helper_private || !plane->helper_private->get_scanout_buffer) + continue; + kmsg_dump_unregister(&plane->kmsg_panic); + } +} +EXPORT_SYMBOL(drm_panic_unregister); diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h index 9ed42469540e..ec59015aec3c 100644 --- a/include/drm/drm_modeset_helper_vtables.h +++ b/include/drm/drm_modeset_helper_vtables.h @@ -48,6 +48,7 @@ * To make this clear all the helper vtables are pulled together in this location here. */ +struct drm_scanout_buffer; struct drm_writeback_connector; struct drm_writeback_job; @@ -1443,6 +1444,44 @@ struct drm_plane_helper_funcs { */ void (*atomic_async_update)(struct drm_plane *plane, struct drm_atomic_state *state); + + /** + * @get_scanout_buffer: + * + * Get the current scanout buffer, to display a message with drm_panic. + * The driver should do the minimum changes to provide a buffer, + * that can be used to display the panic screen. Currently only linear + * buffers are supported. Non-linear buffer support is on the TODO list. + * The device &dev.mode_config.panic_lock is taken before calling this + * function, so you can safely access the &plane.state + * It is called from a panic callback, and must follow its restrictions. + * Please look the documentation at drm_panic_trylock() for an in-depth + * discussions of what's safe and what is not allowed. + * It's a best effort mode, so it's expected that in some complex cases + * the panic screen won't be displayed. + * The returned &drm_scanout_buffer.map must be valid if no error code is + * returned. + * + * Return: + * %0 on success, negative errno on failure. + */ + int (*get_scanout_buffer)(struct drm_plane *plane, + struct drm_scanout_buffer *sb); + + /** + * @panic_flush: + * + * It is used by drm_panic, and is called after the panic screen is + * drawn to the scanout buffer. In this function, the driver + * can send additional commands to the hardware, to make the scanout + * buffer visible. + * It is only called if get_scanout_buffer() returned successfully, and + * the &dev.mode_config.panic_lock is held during the entire sequence. + * It is called from a panic callback, and must follow its restrictions. + * Please look the documentation at drm_panic_trylock() for an in-depth + * discussions of what's safe and what is not allowed. + */ + void (*panic_flush)(struct drm_plane *plane); }; /** diff --git a/include/drm/drm_panic.h b/include/drm/drm_panic.h index 967e02ccc6d5..822dbb1aa9d6 100644 --- a/include/drm/drm_panic.h +++ b/include/drm/drm_panic.h @@ -2,11 +2,56 @@ #ifndef __DRM_PANIC_H__ #define __DRM_PANIC_H__ +#include +#include +#include + #include +#include /* * Copyright (c) 2024 Intel */ +/** + * struct drm_scanout_buffer - DRM scanout buffer + * + * This structure holds the information necessary for drm_panic to draw the + * panic screen, and display it. + */ +struct drm_scanout_buffer { + /** + * @format: + * + * drm format of the scanout buffer. + */ + const struct drm_format_info *format; + + /** + * @map: + * + * Virtual address of the scanout buffer, either in memory or iomem. + * The scanout buffer should be in linear format, and can be directly + * sent to the display hardware. Tearing is not an issue for the panic + * screen. + */ + struct iosys_map map[DRM_FORMAT_MAX_PLANES]; + + /** + * @width: Width of the scanout buffer, in pixels. + */ + unsigned int width; + + /** + * @height: Height of the scanout buffer, in pixels. + */ + unsigned int height; + + /** + * @pitch: Length in bytes between the start of two consecutive lines. + */ + unsigned int pitch[DRM_FORMAT_MAX_PLANES]; +}; + /** * drm_panic_trylock - try to enter the panic printing critical section * @dev: struct drm_device @@ -92,4 +137,16 @@ #define drm_panic_unlock(dev, flags) \ raw_spin_unlock_irqrestore(&(dev)->mode_config.panic_lock, flags) +#ifdef CONFIG_DRM_PANIC + +void drm_panic_register(struct drm_device *dev); +void drm_panic_unregister(struct drm_device *dev); + +#else + +static inline void drm_panic_register(struct drm_device *dev) {} +static inline void drm_panic_unregister(struct drm_device *dev) {} + +#endif + #endif /* __DRM_PANIC_H__ */ diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h index ec1112208b73..9507542121fa 100644 --- a/include/drm/drm_plane.h +++ b/include/drm/drm_plane.h @@ -25,6 +25,7 @@ #include #include +#include #include #include #include @@ -780,6 +781,11 @@ struct drm_plane { * @hotspot_y_property: property to set mouse hotspot y offset. */ struct drm_property *hotspot_y_property; + + /** + * @kmsg_panic: Used to register a panic notifier for this plane + */ + struct kmsg_dumper kmsg_panic; }; #define obj_to_plane(x) container_of(x, struct drm_plane, base) -- cgit v1.2.3