[v4,0/4] drm/panic: Add a QR code panic screen

Message

Jocelyn Falempe July 17, 2024, 2:24 p.m. UTC

This series adds a new panic screen, with the kmsg data embedded in a QR code.

The main advantage of QR code, is that you can copy/paste the debug data to a bug report.

The QR code encoder is written in rust, and is very specific to drm panic.
The reason is that it is called in a panic handler, and thus can't allocate memory, or use locking.
The rust code uses a few rust core API, and provides only two C entry points.
There is no particular reason to do it in rust, I just wanted to learn rust, and see if it can work in the kernel.

If you want to see what it looks like, I've put a few screenshots here:
https://github.com/kdj0c/panic_report/issues/1

v2:
 * Rewrite the rust comments with Markdown (Alice Ryhl)
 * Mark drm_panic_qr_generate() as unsafe (Alice Ryhl)
 * Use CStr directly, and remove the call to as_str_unchecked()
   (Alice Ryhl)
 * Add a check for data_len <= data_size (Greg KH)

v3:
 * Fix all rust comments (typo, punctuation) (Miguel Ojeda)
 * Change the wording of safety comments (Alice Ryhl)
 * Add a link to the javascript decoder in the Kconfig (Greg KH)
 * Fix data_size and tmp_size check in drm_panic_qr_generate()
 
 v4:
 * Fix the logic to find next line and skip the '\n' (Alice Ryhl)
 * Remove __LOG_PREFIX as it's not used (Alice Ryhl)

Jocelyn Falempe (4):
  drm/panic: Add integer scaling to blit()
  drm/rect: Add drm_rect_overlap()
  drm/panic: Simplify logo handling
  drm/panic: Add a QR code panic screen

 drivers/gpu/drm/Kconfig         |   31 +
 drivers/gpu/drm/Makefile        |    1 +
 drivers/gpu/drm/drm_drv.c       |    3 +
 drivers/gpu/drm/drm_panic.c     |  340 +++++++++--
 drivers/gpu/drm/drm_panic_qr.rs | 1003 +++++++++++++++++++++++++++++++
 include/drm/drm_panic.h         |    4 +
 include/drm/drm_rect.h          |   15 +
 7 files changed, 1358 insertions(+), 39 deletions(-)
 create mode 100644 drivers/gpu/drm/drm_panic_qr.rs


base-commit: e1a261ba599eec97e1c5c7760d5c3698fc24e6a6

Comments

Mitchell Levy July 19, 2024, 6:50 p.m. UTC | #1

I am trying to test this patchset on my setup, but I cannot get it 
working. In case it's relevant, I'm running under HyperV. Any 
troubleshooting steps/suggestions would definitely be appreciated.

Thanks!
Mitchell

On 7/17/2024 7:24 AM, Jocelyn Falempe wrote:
> This series adds a new panic screen, with the kmsg data embedded in a QR code.
>
> The main advantage of QR code, is that you can copy/paste the debug data to a bug report.
>
> The QR code encoder is written in rust, and is very specific to drm panic.
> The reason is that it is called in a panic handler, and thus can't allocate memory, or use locking.
> The rust code uses a few rust core API, and provides only two C entry points.
> There is no particular reason to do it in rust, I just wanted to learn rust, and see if it can work in the kernel.
>
> If you want to see what it looks like, I've put a few screenshots here:
> https://github.com/kdj0c/panic_report/issues/1
>
> v2:
>   * Rewrite the rust comments with Markdown (Alice Ryhl)
>   * Mark drm_panic_qr_generate() as unsafe (Alice Ryhl)
>   * Use CStr directly, and remove the call to as_str_unchecked()
>     (Alice Ryhl)
>   * Add a check for data_len <= data_size (Greg KH)
>
> v3:
>   * Fix all rust comments (typo, punctuation) (Miguel Ojeda)
>   * Change the wording of safety comments (Alice Ryhl)
>   * Add a link to the javascript decoder in the Kconfig (Greg KH)
>   * Fix data_size and tmp_size check in drm_panic_qr_generate()
>   
>   v4:
>   * Fix the logic to find next line and skip the '\n' (Alice Ryhl)
>   * Remove __LOG_PREFIX as it's not used (Alice Ryhl)
>
> Jocelyn Falempe (4):
>    drm/panic: Add integer scaling to blit()
>    drm/rect: Add drm_rect_overlap()
>    drm/panic: Simplify logo handling
>    drm/panic: Add a QR code panic screen
>
>   drivers/gpu/drm/Kconfig         |   31 +
>   drivers/gpu/drm/Makefile        |    1 +
>   drivers/gpu/drm/drm_drv.c       |    3 +
>   drivers/gpu/drm/drm_panic.c     |  340 +++++++++--
>   drivers/gpu/drm/drm_panic_qr.rs | 1003 +++++++++++++++++++++++++++++++
>   include/drm/drm_panic.h         |    4 +
>   include/drm/drm_rect.h          |   15 +
>   7 files changed, 1358 insertions(+), 39 deletions(-)
>   create mode 100644 drivers/gpu/drm/drm_panic_qr.rs
>
>
> base-commit: e1a261ba599eec97e1c5c7760d5c3698fc24e6a6

Jocelyn Falempe July 22, 2024, 8:53 a.m. UTC | #2

On 19/07/2024 20:50, Mitchell Levy wrote:
> I am trying to test this patchset on my setup, but I cannot get it 
> working. In case it's relevant, I'm running under HyperV. Any 
> troubleshooting steps/suggestions would definitely be appreciated.

First, make sure you have this in your .config:
CONFIG_RUST=y
CONFIG_DRM_SIMPLEDRM=y
CONFIG_SYSFB_SIMPLEFB=y
CONFIG_DRM_PANIC=y
CONFIG_DRM_PANIC_FOREGROUND_COLOR=0xffffff
CONFIG_DRM_PANIC_BACKGROUND_COLOR=0x000000
CONFIG_DRM_PANIC_DEBUG=y
CONFIG_DRM_PANIC_SCREEN="qr_code"
CONFIG_DRM_PANIC_SCREEN_QR_CODE=y

drm_panic is only supported by a few drivers. The easiest way to test, 
is to use the simpledrm driver, that should work on all EFI or BIOS 
based system.
To check the drm driver in use, run:
sudo udevadm info -a -n /dev/dri/card0 | grep DRIVER

If it's not simpledrm, you should blacklist it, and make sure you boot 
with simpledrm.

and then you can run:
echo 1 > /sys/kernel/debug/dri/0/drm_panic_plane_0

On a side note, looking at the hyperv drm driver, it should be easy to 
add drm_panic support for it. I will look into that when I get some time.

Best regards,