| Message ID | 20240409163432.352518-3-jfalempe@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/panic: Add a drm panic handler | expand |
On Tue, Apr 09, 2024 at 06:30:41PM +0200, Jocelyn Falempe wrote: > 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 <jfalempe@redhat.com> Some detail suggestions for the kerneldoc but those aside Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> > --- > Documentation/gpu/drm-kms.rst | 12 + > drivers/gpu/drm/Kconfig | 23 ++ > drivers/gpu/drm/Makefile | 1 + > drivers/gpu/drm/drm_drv.c | 4 + > drivers/gpu/drm/drm_panic.c | 289 +++++++++++++++++++++++ > include/drm/drm_modeset_helper_vtables.h | 37 +++ > include/drm/drm_panic.h | 57 +++++ > include/drm/drm_plane.h | 6 + > 8 files changed, 429 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 13d3627d8bc0..b64334661aeb 100644 > --- a/Documentation/gpu/drm-kms.rst > +++ b/Documentation/gpu/drm-kms.rst > @@ -398,6 +398,18 @@ 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:: 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 <drm/drm_file.h> > #include <drm/drm_managed.h> > #include <drm/drm_mode_object.h> > +#include <drm/drm_panic.h> > #include <drm/drm_print.h> > #include <drm/drm_privacy_screen_machine.h> > > @@ -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..fa4b220534a4 > --- /dev/null > +++ b/drivers/gpu/drm/drm_panic.c > @@ -0,0 +1,289 @@ > +// SPDX-License-Identifier: GPL-2.0 or MIT > +/* > + * Copyright (c) 2023 Red Hat. > + * Author: Jocelyn Falempe <jfalempe@redhat.com> > + * inspired by the drm_log driver from David Herrmann <dh.herrmann@gmail.com> > + * 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/kmsg_dump.h> > +#include <linux/list.h> > +#include <linux/module.h> > +#include <linux/types.h> > + > +#include <drm/drm_drv.h> > +#include <drm/drm_format_helper.h> > +#include <drm/drm_fourcc.h> > +#include <drm/drm_framebuffer.h> > +#include <drm/drm_modeset_helper_vtables.h> > +#include <drm/drm_panic.h> > +#include <drm/drm_plane.h> > +#include <drm/drm_print.h> > + > + > +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 > + * get_scanout_buffer() helper function. It is then automatically registered to > + * the drm panic handler. > + * When a panic occurs, the get_scanout_buffer() will be called, and the driver > + * can provide a framebuffer so the panic handler can draw the panic screen on > + * it. The buffer provided must be linear, and use a supported color format. > + * Optionally the driver can also provide a 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..5470ba1ced00 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 +1444,42 @@ 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 linear buffer, > + * that can be used to display the panic screen. I'd change this to note that currently only linear buffers are supported, and supporting tiled formats or other more special formats is a todo item when we get around to adding support for that. > + * The device dev->mode_config.panic_lock is taken before calling this > + * function, so you can safely access the plane->state &drm_mode_config.panic_lock and &drm_plane.state for nice links. > + * It is called from a panic callback, and must follow its restrictions. > + * (no locks, no memory allocation, no sleep, no thread/workqueue, ...) Maybe instead of just "it's restrictions" add "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 scanout_buffer->map must be valid if no error code is &drm_scanout_buffer.map so it's a nice link please. > + * returned. > + * > + * Returns: > + * > + * Zero 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. > + * 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. > + * (no locks, no memory allocation, no sleep, no thread/workqueue, ...) I'd add here that this is only called when @get_scanout_buffer has returned successfully, and it's all done while holding &drm_mode_config.panic_lock for the entire sequence. > + */ > + void (*panic_flush)(struct drm_plane *plane); > }; > > /** > diff --git a/include/drm/drm_panic.h b/include/drm/drm_panic.h > index 68f57710d2d1..2a2346cd0040 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 <linux/module.h> > +#include <linux/types.h> > +#include <linux/iosys-map.h> > + > #include <drm/drm_device.h> > +#include <drm/drm_fourcc.h> > /* > * 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 > @@ -97,4 +142,16 @@ > #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 641fe298052d..b9a2fc0a820d 100644 > --- a/include/drm/drm_plane.h > +++ b/include/drm/drm_plane.h > @@ -25,6 +25,7 @@ > > #include <linux/list.h> > #include <linux/ctype.h> > +#include <linux/kmsg_dump.h> > #include <drm/drm_mode_object.h> > #include <drm/drm_color_mgmt.h> > #include <drm/drm_rect.h> > @@ -779,6 +780,11 @@ 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) > -- > 2.44.0 >
Hi, On 10/04/2024 10:10, Daniel Vetter wrote: > On Tue, Apr 09, 2024 at 06:30:41PM +0200, Jocelyn Falempe wrote: >> 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 <jfalempe@redhat.com> > > Some detail suggestions for the kerneldoc but those aside Acked-by: Daniel > Vetter <daniel.vetter@ffwll.ch> Thanks for the review. I fixed the documentation, and make sure the links are working. >> --- >> Documentation/gpu/drm-kms.rst | 12 + >> drivers/gpu/drm/Kconfig | 23 ++ >> drivers/gpu/drm/Makefile | 1 + >> drivers/gpu/drm/drm_drv.c | 4 + >> drivers/gpu/drm/drm_panic.c | 289 +++++++++++++++++++++++ >> include/drm/drm_modeset_helper_vtables.h | 37 +++ >> include/drm/drm_panic.h | 57 +++++ >> include/drm/drm_plane.h | 6 + >> 8 files changed, 429 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 13d3627d8bc0..b64334661aeb 100644 >> --- a/Documentation/gpu/drm-kms.rst >> +++ b/Documentation/gpu/drm-kms.rst >> @@ -398,6 +398,18 @@ 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:: 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 <drm/drm_file.h> >> #include <drm/drm_managed.h> >> #include <drm/drm_mode_object.h> >> +#include <drm/drm_panic.h> >> #include <drm/drm_print.h> >> #include <drm/drm_privacy_screen_machine.h> >> >> @@ -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..fa4b220534a4 >> --- /dev/null >> +++ b/drivers/gpu/drm/drm_panic.c >> @@ -0,0 +1,289 @@ >> +// SPDX-License-Identifier: GPL-2.0 or MIT >> +/* >> + * Copyright (c) 2023 Red Hat. >> + * Author: Jocelyn Falempe <jfalempe@redhat.com> >> + * inspired by the drm_log driver from David Herrmann <dh.herrmann@gmail.com> >> + * 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/kmsg_dump.h> >> +#include <linux/list.h> >> +#include <linux/module.h> >> +#include <linux/types.h> >> + >> +#include <drm/drm_drv.h> >> +#include <drm/drm_format_helper.h> >> +#include <drm/drm_fourcc.h> >> +#include <drm/drm_framebuffer.h> >> +#include <drm/drm_modeset_helper_vtables.h> >> +#include <drm/drm_panic.h> >> +#include <drm/drm_plane.h> >> +#include <drm/drm_print.h> >> + >> + >> +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 >> + * get_scanout_buffer() helper function. It is then automatically registered to >> + * the drm panic handler. >> + * When a panic occurs, the get_scanout_buffer() will be called, and the driver >> + * can provide a framebuffer so the panic handler can draw the panic screen on >> + * it. The buffer provided must be linear, and use a supported color format. >> + * Optionally the driver can also provide a 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..5470ba1ced00 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 +1444,42 @@ 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 linear buffer, >> + * that can be used to display the panic screen. > > I'd change this to note that currently only linear buffers are supported, > and supporting tiled formats or other more special formats is a todo item > when we get around to adding support for that. Yes, I agree, we want to support non-linear format in the future. > >> + * The device dev->mode_config.panic_lock is taken before calling this >> + * function, so you can safely access the plane->state > &drm_mode_config.panic_lock and &drm_plane.state for nice > links. > >> + * It is called from a panic callback, and must follow its restrictions. >> + * (no locks, no memory allocation, no sleep, no thread/workqueue, ...) > > Maybe instead of just "it's restrictions" add "Please look the > documentation at drm_panic_trylock() for an in-depth discussions of what's > safe and what is not allowed."Done > >> + * It's a best effort mode, so it's expected that in some complex cases >> + * the panic screen won't be displayed. >> + * The returned scanout_buffer->map must be valid if no error code is > > &drm_scanout_buffer.map so it's a nice link > please. > Sure, I fixed a bunch of links in this documentation. >> + * returned. >> + * >> + * Returns: >> + * >> + * Zero 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. >> + * 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. >> + * (no locks, no memory allocation, no sleep, no thread/workqueue, ...) > > I'd add here that this is only called when @get_scanout_buffer has > returned successfully, and it's all done while holding > &drm_mode_config.panic_lock for the entire sequence. Done too. >> + */ >> + void (*panic_flush)(struct drm_plane *plane); >> }; >> >> /** >> diff --git a/include/drm/drm_panic.h b/include/drm/drm_panic.h >> index 68f57710d2d1..2a2346cd0040 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 <linux/module.h> >> +#include <linux/types.h> >> +#include <linux/iosys-map.h> >> + >> #include <drm/drm_device.h> >> +#include <drm/drm_fourcc.h> >> /* >> * 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 >> @@ -97,4 +142,16 @@ >> #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 641fe298052d..b9a2fc0a820d 100644 >> --- a/include/drm/drm_plane.h >> +++ b/include/drm/drm_plane.h >> @@ -25,6 +25,7 @@ >> >> #include <linux/list.h> >> #include <linux/ctype.h> >> +#include <linux/kmsg_dump.h> >> #include <drm/drm_mode_object.h> >> #include <drm/drm_color_mgmt.h> >> #include <drm/drm_rect.h> >> @@ -779,6 +780,11 @@ 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) >> -- >> 2.44.0 >> > Best regards,
diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst index 13d3627d8bc0..b64334661aeb 100644 --- a/Documentation/gpu/drm-kms.rst +++ b/Documentation/gpu/drm-kms.rst @@ -398,6 +398,18 @@ 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:: 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 <drm/drm_file.h> #include <drm/drm_managed.h> #include <drm/drm_mode_object.h> +#include <drm/drm_panic.h> #include <drm/drm_print.h> #include <drm/drm_privacy_screen_machine.h> @@ -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..fa4b220534a4 --- /dev/null +++ b/drivers/gpu/drm/drm_panic.c @@ -0,0 +1,289 @@ +// SPDX-License-Identifier: GPL-2.0 or MIT +/* + * Copyright (c) 2023 Red Hat. + * Author: Jocelyn Falempe <jfalempe@redhat.com> + * inspired by the drm_log driver from David Herrmann <dh.herrmann@gmail.com> + * 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/kmsg_dump.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/types.h> + +#include <drm/drm_drv.h> +#include <drm/drm_format_helper.h> +#include <drm/drm_fourcc.h> +#include <drm/drm_framebuffer.h> +#include <drm/drm_modeset_helper_vtables.h> +#include <drm/drm_panic.h> +#include <drm/drm_plane.h> +#include <drm/drm_print.h> + + +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 + * get_scanout_buffer() helper function. It is then automatically registered to + * the drm panic handler. + * When a panic occurs, the get_scanout_buffer() will be called, and the driver + * can provide a framebuffer so the panic handler can draw the panic screen on + * it. The buffer provided must be linear, and use a supported color format. + * Optionally the driver can also provide a 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..5470ba1ced00 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 +1444,42 @@ 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 linear buffer, + * that can be used to display the panic screen. + * 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. + * (no locks, no memory allocation, no sleep, no thread/workqueue, ...) + * It's a best effort mode, so it's expected that in some complex cases + * the panic screen won't be displayed. + * The returned scanout_buffer->map must be valid if no error code is + * returned. + * + * Returns: + * + * Zero 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. + * 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. + * (no locks, no memory allocation, no sleep, no thread/workqueue, ...) + */ + void (*panic_flush)(struct drm_plane *plane); }; /** diff --git a/include/drm/drm_panic.h b/include/drm/drm_panic.h index 68f57710d2d1..2a2346cd0040 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 <linux/module.h> +#include <linux/types.h> +#include <linux/iosys-map.h> + #include <drm/drm_device.h> +#include <drm/drm_fourcc.h> /* * 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 @@ -97,4 +142,16 @@ #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 641fe298052d..b9a2fc0a820d 100644 --- a/include/drm/drm_plane.h +++ b/include/drm/drm_plane.h @@ -25,6 +25,7 @@ #include <linux/list.h> #include <linux/ctype.h> +#include <linux/kmsg_dump.h> #include <drm/drm_mode_object.h> #include <drm/drm_color_mgmt.h> #include <drm/drm_rect.h> @@ -779,6 +780,11 @@ 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)
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 <jfalempe@redhat.com> --- Documentation/gpu/drm-kms.rst | 12 + drivers/gpu/drm/Kconfig | 23 ++ drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/drm_drv.c | 4 + drivers/gpu/drm/drm_panic.c | 289 +++++++++++++++++++++++ include/drm/drm_modeset_helper_vtables.h | 37 +++ include/drm/drm_panic.h | 57 +++++ include/drm/drm_plane.h | 6 + 8 files changed, 429 insertions(+) create mode 100644 drivers/gpu/drm/drm_panic.c