--- /dev/null
+// 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
+ * &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);
projects / linux-block.git / commitdiff