Hi
Am 18.06.24 um 11:35 schrieb Daniel Vetter:
On Mon, Jun 17, 2024 at 05:26:37PM +0200, Thomas Zimmermann wrote:
Only export struct fb_info.fix.smem_start if that is required by the
user and the memory does not come from vmalloc().
Setting struct fb_info.fix.smem_start breaks systems where DMA
memory is backed by vmalloc address space. An example error is
shown below.
[ 3.536043] ------------[ cut here ]------------
[ 3.540716] virt_to_phys used for non-linear address: 000000007fc4f540 (0xffff800086001000)
[ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12 __virt_to_phys+0x68/0x98
[ 3.565455] Modules linked in:
[ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted 6.6.23-06226-g4986cc3e1b75-dirty #250
[ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT)
[ 3.582452] Workqueue: events_unbound deferred_probe_work_func
[ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 3.595233] pc : __virt_to_phys+0x68/0x98
[ 3.599246] lr : __virt_to_phys+0x68/0x98
[ 3.603276] sp : ffff800083603990
[ 3.677939] Call trace:
[ 3.680393] __virt_to_phys+0x68/0x98
[ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238
[ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0
[ 3.695385] drm_fb_helper_initial_config+0x4c/0x68
[ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0
[ 3.705161] drm_client_register+0x60/0xb0
[ 3.709269] drm_fbdev_dma_setup+0x94/0x148
Additionally, DMA memory is assumed to by contiguous in physical
address space, which is not guaranteed by vmalloc().
Resolve this by checking the module flag drm_leak_fbdev_smem when
DRM allocated the instance of struct fb_info. Fbdev-dma then only
sets smem_start only if required (via FBINFO_HIDE_SMEM_START). Also
guarantee that the framebuffer is not located in vmalloc address
space.
Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Reported-by: Peng Fan (OSS) <peng.fan@xxxxxxxxxxx>
Closes: https://lore.kernel.org/dri-devel/20240604080328.4024838-1-peng.fan@xxxxxxxxxxx/
Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for GEM DMA helpers")
---
drivers/gpu/drm/drm_fb_helper.c | 6 +++---
drivers/gpu/drm/drm_fbdev_dma.c | 5 ++++-
2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index e2e19f49342e1..18565ec684517 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -517,6 +517,9 @@ struct fb_info *drm_fb_helper_alloc_info(struct drm_fb_helper *fb_helper)
if (!info)
return ERR_PTR(-ENOMEM);
+ if (!drm_leak_fbdev_smem)
+ info->flags |= FBINFO_HIDE_SMEM_START;
+
ret = fb_alloc_cmap(&info->cmap, 256, 0);
if (ret)
goto err_release;
@@ -1853,9 +1856,6 @@ __drm_fb_helper_initial_config_and_unlock(struct drm_fb_helper *fb_helper)
info = fb_helper->info;
info->var.pixclock = 0;
- if (!drm_leak_fbdev_smem)
- info->flags |= FBINFO_HIDE_SMEM_START;
-
/* Need to drop locks to avoid recursive deadlock in
* register_framebuffer. This is ok because the only thing left to do is
* register the fbdev emulation instance in kernel_fb_helper_list. */
diff --git a/drivers/gpu/drm/drm_fbdev_dma.c b/drivers/gpu/drm/drm_fbdev_dma.c
index 97ef6300d47e0..4b0527ddeb5a7 100644
--- a/drivers/gpu/drm/drm_fbdev_dma.c
+++ b/drivers/gpu/drm/drm_fbdev_dma.c
@@ -137,7 +137,10 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper,
info->flags |= FBINFO_READS_FAST; /* signal caching */
info->screen_size = sizes->surface_height * fb->pitches[0];
info->screen_buffer = map.vaddr;
- info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer));
+ if (!(info->flags & FBINFO_HIDE_SMEM_START)) {
I guess since the WARN is conditional on the explicit opt-in with
drm_leak_fbdev_smem it should be fine.
Yes, that's the intention. If someone enables this flag, it warns if
that's not supported. By default, smem_start is clear.
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Thanks
Best regards
Thomas
+ if (!drm_WARN_ON(dev, is_vmalloc_addr(info->screen_buffer)))
+ info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer));
+ }
info->fix.smem_len = info->screen_size;
/* deferred I/O */
--
2.45.2
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
