| Message ID | 20240409163432.352518-5-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 06:30:43PM +0200, Jocelyn Falempe wrote: > Add a debugfs file, so you can test drm_panic without freezing > your machine. This is unsafe, and should be enabled only for > developer or tester. > > To display the drm_panic screen on the device 0: > echo 1 > /sys/kernel/debug/dri/0/drm_panic_plane_0 > > v9: > * Create a debugfs file for each plane in the device's debugfs > directory. This allows to test for each plane of each GPU > independently. > > Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com> I was pondering whether this guarantees that the debugfs file disappears before drm_dev_unregister finishes (otherwise we have a bit a problem), and looks like we're good. Maybe add a todo that it would be nice to simulate nmi context, not sure lockdept can help here ... Anyway Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> > --- > drivers/gpu/drm/Kconfig | 9 ++++++++ > drivers/gpu/drm/drm_panic.c | 43 ++++++++++++++++++++++++++++++++++++- > 2 files changed, 51 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig > index f8a26423369e..959b19a04101 100644 > --- a/drivers/gpu/drm/Kconfig > +++ b/drivers/gpu/drm/Kconfig > @@ -127,6 +127,15 @@ config DRM_PANIC_BACKGROUND_COLOR > depends on DRM_PANIC > default 0x000000 > > +config DRM_PANIC_DEBUG > + bool "Add a debug fs entry to trigger drm_panic" > + depends on DRM_PANIC && DEBUG_FS > + help > + Add dri/[device]/drm_panic_plane_x in the kernel debugfs, to force the > + panic handler to write the panic message to this plane scanout buffer. > + This is unsafe and should not be enabled on a production build. > + If in doubt, say "N". > + > 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/drm_panic.c b/drivers/gpu/drm/drm_panic.c > index e1ec30b6c04a..78fd6d5d7adc 100644 > --- a/drivers/gpu/drm/drm_panic.c > +++ b/drivers/gpu/drm/drm_panic.c > @@ -495,6 +495,45 @@ static void drm_panic(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason) > draw_panic_plane(plane); > } > > + > +/* > + * DEBUG FS, This is currently unsafe. > + * Create one file per plane, so it's possible to debug one plane at a time. > + */ > +#ifdef CONFIG_DRM_PANIC_DEBUG > +#include <linux/debugfs.h> > + > +static ssize_t debugfs_trigger_write(struct file *file, const char __user *user_buf, > + size_t count, loff_t *ppos) > +{ > + bool run; > + > + if (kstrtobool_from_user(user_buf, count, &run) == 0 && run) { > + struct drm_plane *plane = file->private_data; > + > + draw_panic_plane(plane); > + } > + return count; > +} > + > +static const struct file_operations dbg_drm_panic_ops = { > + .owner = THIS_MODULE, > + .write = debugfs_trigger_write, > + .open = simple_open, > +}; > + > +static void debugfs_register_plane(struct drm_plane *plane, int index) > +{ > + char fname[32]; > + > + snprintf(fname, 32, "drm_panic_plane_%d", index); > + debugfs_create_file(fname, 0200, plane->dev->debugfs_root, > + plane, &dbg_drm_panic_ops); > +} > +#else > +static void debugfs_register_plane(struct drm_plane *plane, int index) {} > +#endif /* CONFIG_DRM_PANIC_DEBUG */ > + > /** > * drm_panic_register() - Initialize DRM panic for a device > * @dev: the drm device on which the panic screen will be displayed. > @@ -514,8 +553,10 @@ void drm_panic_register(struct drm_device *dev) > 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 > + else { > + debugfs_register_plane(plane, registered_plane); > registered_plane++; > + } > } > if (registered_plane) > drm_info(dev, "Registered %d planes with drm panic\n", registered_plane); > -- > 2.44.0 >
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index f8a26423369e..959b19a04101 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -127,6 +127,15 @@ config DRM_PANIC_BACKGROUND_COLOR depends on DRM_PANIC default 0x000000 +config DRM_PANIC_DEBUG + bool "Add a debug fs entry to trigger drm_panic" + depends on DRM_PANIC && DEBUG_FS + help + Add dri/[device]/drm_panic_plane_x in the kernel debugfs, to force the + panic handler to write the panic message to this plane scanout buffer. + This is unsafe and should not be enabled on a production build. + If in doubt, say "N". + 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/drm_panic.c b/drivers/gpu/drm/drm_panic.c index e1ec30b6c04a..78fd6d5d7adc 100644 --- a/drivers/gpu/drm/drm_panic.c +++ b/drivers/gpu/drm/drm_panic.c @@ -495,6 +495,45 @@ static void drm_panic(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason) draw_panic_plane(plane); } + +/* + * DEBUG FS, This is currently unsafe. + * Create one file per plane, so it's possible to debug one plane at a time. + */ +#ifdef CONFIG_DRM_PANIC_DEBUG +#include <linux/debugfs.h> + +static ssize_t debugfs_trigger_write(struct file *file, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + bool run; + + if (kstrtobool_from_user(user_buf, count, &run) == 0 && run) { + struct drm_plane *plane = file->private_data; + + draw_panic_plane(plane); + } + return count; +} + +static const struct file_operations dbg_drm_panic_ops = { + .owner = THIS_MODULE, + .write = debugfs_trigger_write, + .open = simple_open, +}; + +static void debugfs_register_plane(struct drm_plane *plane, int index) +{ + char fname[32]; + + snprintf(fname, 32, "drm_panic_plane_%d", index); + debugfs_create_file(fname, 0200, plane->dev->debugfs_root, + plane, &dbg_drm_panic_ops); +} +#else +static void debugfs_register_plane(struct drm_plane *plane, int index) {} +#endif /* CONFIG_DRM_PANIC_DEBUG */ + /** * drm_panic_register() - Initialize DRM panic for a device * @dev: the drm device on which the panic screen will be displayed. @@ -514,8 +553,10 @@ void drm_panic_register(struct drm_device *dev) 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 + else { + debugfs_register_plane(plane, registered_plane); registered_plane++; + } } if (registered_plane) drm_info(dev, "Registered %d planes with drm panic\n", registered_plane);
Add a debugfs file, so you can test drm_panic without freezing your machine. This is unsafe, and should be enabled only for developer or tester. To display the drm_panic screen on the device 0: echo 1 > /sys/kernel/debug/dri/0/drm_panic_plane_0 v9: * Create a debugfs file for each plane in the device's debugfs directory. This allows to test for each plane of each GPU independently. Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com> --- drivers/gpu/drm/Kconfig | 9 ++++++++ drivers/gpu/drm/drm_panic.c | 43 ++++++++++++++++++++++++++++++++++++- 2 files changed, 51 insertions(+), 1 deletion(-)