path: root/drivers/gpu/drm/drm_panic.c

// 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/init.h>
#include <linux/iosys-map.h>
#include <linux/kdebug.h>
#include <linux/kmsg_dump.h>
#include <linux/linux_logo.h>
#include <linux/list.h>
#include <linux/math.h>
#include <linux/module.h>
#include <linux/overflow.h>
#include <linux/printk.h>
#include <linux/types.h>
#include <linux/utsname.h>
#include <linux/zlib.h>

#include <drm/drm_drv.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>
#include <drm/drm_rect.h>

#include "drm_crtc_internal.h"

MODULE_AUTHOR("Jocelyn Falempe");
MODULE_DESCRIPTION("DRM panic handler");
MODULE_LICENSE("GPL");

static char drm_panic_screen[16] = CONFIG_DRM_PANIC_SCREEN;
module_param_string(panic_screen, drm_panic_screen, sizeof(drm_panic_screen), 0644);
MODULE_PARM_DESC(panic_screen,
		 "Choose what will be displayed by drm_panic, 'user' or 'kmsg' [default="
		 CONFIG_DRM_PANIC_SCREEN "]");

/**
 * 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."),
	PANIC_LINE(""),
	PANIC_LINE(""), /* will be replaced by the panic description */
};

static const size_t panic_msg_lines = ARRAY_SIZE(panic_msg);

static const struct drm_panic_line logo_ascii[] = {
	PANIC_LINE("     .--.        _"),
	PANIC_LINE("    |o_o |      | |"),
	PANIC_LINE("    |:_/ |      | |"),
	PANIC_LINE("   //   \\ \\     |_|"),
	PANIC_LINE("  (|     | )     _"),
	PANIC_LINE(" /'\\_   _/`\\    (_)"),
	PANIC_LINE(" \\___)=(___/"),
};

static const size_t logo_ascii_lines = ARRAY_SIZE(logo_ascii);

#if defined(CONFIG_LOGO) && !defined(MODULE)
static const struct linux_logo *logo_mono;

static int drm_panic_setup_logo(void)
{
	const struct linux_logo *logo = fb_find_logo(1);
	const unsigned char *logo_data;
	struct linux_logo *logo_dup;

	if (!logo || logo->type != LINUX_LOGO_MONO)
		return 0;

	/* The logo is __init, so we must make a copy for later use */
	logo_data = kmemdup(logo->data,
			    size_mul(DIV_ROUND_UP(logo->width, BITS_PER_BYTE), logo->height),
			    GFP_KERNEL);
	if (!logo_data)
		return -ENOMEM;

	logo_dup = kmemdup(logo, sizeof(*logo), GFP_KERNEL);
	if (!logo_dup) {
		kfree(logo_data);
		return -ENOMEM;
	}

	logo_dup->data = logo_data;
	logo_mono = logo_dup;

	return 0;
}

device_initcall(drm_panic_setup_logo);
#else
#define logo_mono	((const struct linux_logo *)NULL)
#endif

/*
 * Color conversion
 */

static u16 convert_xrgb8888_to_rgb565(u32 pix)
{
	return ((pix & 0x00F80000) >> 8) |
	       ((pix & 0x0000FC00) >> 5) |
	       ((pix & 0x000000F8) >> 3);
}

static u16 convert_xrgb8888_to_rgba5551(u32 pix)
{
	return ((pix & 0x00f80000) >> 8) |
	       ((pix & 0x0000f800) >> 5) |
	       ((pix & 0x000000f8) >> 2) |
	       BIT(0); /* set alpha bit */
}

static u16 convert_xrgb8888_to_xrgb1555(u32 pix)
{
	return ((pix & 0x00f80000) >> 9) |
	       ((pix & 0x0000f800) >> 6) |
	       ((pix & 0x000000f8) >> 3);
}

static u16 convert_xrgb8888_to_argb1555(u32 pix)
{
	return BIT(15) | /* set alpha bit */
	       ((pix & 0x00f80000) >> 9) |
	       ((pix & 0x0000f800) >> 6) |
	       ((pix & 0x000000f8) >> 3);
}

static u32 convert_xrgb8888_to_argb8888(u32 pix)
{
	return pix | GENMASK(31, 24); /* fill alpha bits */
}

static u32 convert_xrgb8888_to_xbgr8888(u32 pix)
{
	return ((pix & 0x00ff0000) >> 16) <<  0 |
	       ((pix & 0x0000ff00) >>  8) <<  8 |
	       ((pix & 0x000000ff) >>  0) << 16 |
	       ((pix & 0xff000000) >> 24) << 24;
}

static u32 convert_xrgb8888_to_abgr8888