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drm/panic: Add a kmsg panic screen

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Add a kmsg option, which will display the last lines of kmsg,
and should be similar to fbcon.
Add a drm.panic_screen module parameter, so you can choose between
the different panic screens available.
two options currently, but more will be added later:
 * "user": a short message telling the user to reboot the machine.
 * "kmsg": fill the screen with the last lines of kmsg.

You can even change it at runtime by writing to
/sys/module/drm/parameters/panic_screen

v2:
 * Use module parameter instead of Kconfig choice
   (Javier Martinez Canillas)

v3:
 * Add help for module parameter usage in Kconfig
   (Javier Martivez Canillas)
 * Fix use of font->height before checking it isn't null.
   (kernel test robot, Dan Carpenter)

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240603095343.39588-4-jfalempe@redhat.com
This commit is contained in:
Jocelyn Falempe 2024-06-03 11:47:27 +02:00
parent 24d07f114e
commit 54034bebb2
2 changed files with 112 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/gpu/drm/Kconfig
View File

@ -137,6 +137,19 @@ config DRM_PANIC_DEBUG
This is unsafe and should not be enabled on a production build.
If in doubt, say "N".
config DRM_PANIC_SCREEN
string "Panic screen formater"
default "user"
depends on DRM_PANIC
help
This option enable to choose what will be displayed when a kernel
panic occurs. You can choose between "user", a short message telling
the user to reboot the system, or "kmsg" which will display the last
lines of kmsg.
This can also be overridden by drm.panic_screen=xxxx kernel parameter
or by writing to /sys/module/drm/parameters/panic_screen sysfs entry
Default is "user"
config DRM_DEBUG_DP_MST_TOPOLOGY_REFS
bool "Enable refcount backtrace history in the DP MST helpers"
depends on STACKTRACE_SUPPORT

109
drivers/gpu/drm/drm_panic.c
View File

@ -12,6 +12,7 @@
#include <linux/kmsg_dump.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/types.h>
#include <drm/drm_drv.h>
@ -27,6 +28,12 @@ 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
*
@ -437,24 +444,18 @@ static void draw_txt_rectangle(struct drm_scanout_buffer *sb,
}
}
/*
* Draw the panic message at the center of the screen
*/
static void draw_panic_static(struct drm_scanout_buffer *sb)
static void draw_panic_static_user(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;
u32 fg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR, sb->format->format);
u32 bg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR, sb->format->format);
const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
struct drm_rect r_screen, r_logo, r_msg;
if (!font)
return;
fg_color = convert_from_xrgb8888(fg_color, sb->format->format);
bg_color = convert_from_xrgb8888(bg_color, sb->format->format);
r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);
r_logo = DRM_RECT_INIT(0, 0,
@ -477,6 +478,85 @@ static void draw_panic_static(struct drm_scanout_buffer *sb)
draw_txt_rectangle(sb, font, panic_msg, msg_lines, true, &r_msg, fg_color);
}
/*
* Draw one line of kmsg, and handle wrapping if it won't fit in the screen width.
* Return the y-offset of the next line.
*/
static int draw_line_with_wrap(struct drm_scanout_buffer *sb, const struct font_desc *font,
struct drm_panic_line *line, int yoffset, u32 fg_color)
{
int chars_per_row = sb->width / font->width;
struct drm_rect r_txt = DRM_RECT_INIT(0, yoffset, sb->width, sb->height);
struct drm_panic_line line_wrap;
if (line->len > chars_per_row) {
line_wrap.len = line->len % chars_per_row;
line_wrap.txt = line->txt + line->len - line_wrap.len;
draw_txt_rectangle(sb, font, &line_wrap, 1, false, &r_txt, fg_color);
r_txt.y1 -= font->height;
if (r_txt.y1 < 0)
return r_txt.y1;
while (line_wrap.txt > line->txt) {
line_wrap.txt -= chars_per_row;
line_wrap.len = chars_per_row;
draw_txt_rectangle(sb, font, &line_wrap, 1, false, &r_txt, fg_color);
r_txt.y1 -= font->height;
if (r_txt.y1 < 0)
return r_txt.y1;
}
} else {
draw_txt_rectangle(sb, font, line, 1, false, &r_txt, fg_color);
r_txt.y1 -= font->height;
}
return r_txt.y1;
}
/*
* Draw the kmsg buffer to the screen, starting from the youngest message at the bottom,
* and going up until reaching the top of the screen.
*/
static void draw_panic_static_kmsg(struct drm_scanout_buffer *sb)
{
u32 fg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR, sb->format->format);
u32 bg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR, sb->format->format);
const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
struct drm_rect r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);
struct kmsg_dump_iter iter;
char kmsg_buf[512];
size_t kmsg_len;
struct drm_panic_line line;
int yoffset;
if (!font)
return;
yoffset = sb->height - font->height - (sb->height % font->height) / 2;
/* Fill with the background color, and draw text on top */
drm_panic_fill(sb, &r_screen, bg_color);
kmsg_dump_rewind(&iter);
while (kmsg_dump_get_buffer(&iter, false, kmsg_buf, sizeof(kmsg_buf), &kmsg_len)) {
char *start;
char *end;
/* ignore terminating NUL and newline */
start = kmsg_buf + kmsg_len - 2;
end = kmsg_buf + kmsg_len - 1;
while (start > kmsg_buf && yoffset >= 0) {
while (start > kmsg_buf && *start != '\n')
start--;
/* don't count the newline character */
line.txt = start + (start == kmsg_buf ? 0 : 1);
line.len = end - line.txt;
yoffset = draw_line_with_wrap(sb, font, &line, yoffset, fg_color);
end = start;
start--;
}
}
}
/*
* drm_panic_is_format_supported()
* @format: a fourcc color code
@ -491,6 +571,15 @@ static bool drm_panic_is_format_supported(const struct drm_format_info *format)
return convert_from_xrgb8888(0xffffff, format->format) != 0;
}
static void draw_panic_dispatch(struct drm_scanout_buffer *sb)
{
if (!strcmp(drm_panic_screen, "kmsg")) {
draw_panic_static_kmsg(sb);
} else {
draw_panic_static_user(sb);
}
}
static void draw_panic_plane(struct drm_plane *plane)
{
struct drm_scanout_buffer sb;
@ -503,7 +592,7 @@ static void draw_panic_plane(struct drm_plane *plane)
ret = plane->helper_private->get_scanout_buffer(plane, &sb);
if (!ret && drm_panic_is_format_supported(sb.format)) {
draw_panic_static(&sb);
draw_panic_dispatch(&sb);
if (plane->helper_private->panic_flush)
plane->helper_private->panic_flush(plane);
}