On Fri, Apr 14, 2023 at 06:58:53PM +0800, Sui Jingfeng wrote: > Hi, > > On 2023/4/14 03:16, Thomas Zimmermann wrote: > > Hi, > > > > thanks for the patch. This is effectively a revert of commit > > 8fbc9af55de0 ("drm/fbdev-generic: Set screen size to size of GEM > > buffer"). Please add a Fixes tag. > > > > Am 13.04.23 um 20:06 schrieb Sui Jingfeng: > > > From: Sui Jingfeng <suijingfeng@xxxxxxxxxxx> > > > > > > The crazy fbdev test of IGT may write after EOF, which lead to > > > out-of-bound > > > > Please drop 'crazy'. :) > > This is OK. > > By using the world 'crazy', > > I meant that the test is very good and maybe it is written by professional > peoples > > with the guidance by experienced engineer. So that even the corner get > tested. 'thoroughly' would be better word to describe that I think. I think for the other discussions I've covered it all already in the other thread. -Daniel > > > > > > > access for the drm drivers using fbdev-generic. For example, run > > > fbdev test > > > on a x86-64+ast2400 platform with 1680x1050 resolution will cause > > > the linux > > > kernel hang with following call trace: > > > > > > Oops: 0000 [#1] PREEMPT SMP PTI > > > [IGT] fbdev: starting subtest eof > > > Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] > > > [IGT] fbdev: starting subtest nullptr > > > > > > RIP: 0010:memcpy_erms+0xa/0x20 > > > RSP: 0018:ffffa17d40167d98 EFLAGS: 00010246 > > > RAX: ffffa17d4eb7fa80 RBX: ffffa17d40e0aa80 RCX: 00000000000014c0 > > > RDX: 0000000000001a40 RSI: ffffa17d40e0b000 RDI: ffffa17d4eb80000 > > > RBP: ffffa17d40167e20 R08: 0000000000000000 R09: ffff89522ecff8c0 > > > R10: ffffa17d4e4c5000 R11: 0000000000000000 R12: ffffa17d4eb7fa80 > > > R13: 0000000000001a40 R14: 000000000000041a R15: ffffa17d40167e30 > > > FS: 0000000000000000(0000) GS:ffff895257380000(0000) > > > knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: ffffa17d40e0b000 CR3: 00000001eaeca006 CR4: 00000000001706e0 > > > Call Trace: > > > <TASK> > > > ? drm_fbdev_generic_helper_fb_dirty+0x207/0x330 [drm_kms_helper] > > > drm_fb_helper_damage_work+0x8f/0x170 [drm_kms_helper] > > > process_one_work+0x21f/0x430 > > > worker_thread+0x4e/0x3c0 > > > ? __pfx_worker_thread+0x10/0x10 > > > kthread+0xf4/0x120 > > > ? __pfx_kthread+0x10/0x10 > > > ret_from_fork+0x2c/0x50 > > > </TASK> > > > CR2: ffffa17d40e0b000 > > > ---[ end trace 0000000000000000 ]--- > > > > > > The indirect reason is drm_fb_helper_memory_range_to_clip() generate > > > damage > > > rectangles which partially or completely go out of the active > > > display area. > > > The second of argument 'off' is passing from the user-space, this > > > will lead > > > to the out-of-bound if it is large than (fb_height + 1) * > > > fb_pitches; while > > > DIV_ROUND_UP() may also controbute to error by 1. > > > > > > This patch will add code to restrict the damage rect computed go > > > beyond of > > > the last line of the framebuffer. > > > > > > Signed-off-by: Sui Jingfeng <suijingfeng@xxxxxxxxxxx> > > > --- > > > drivers/gpu/drm/drm_fb_helper.c | 16 ++++++++++++---- > > > drivers/gpu/drm/drm_fbdev_generic.c | 2 +- > > > 2 files changed, 13 insertions(+), 5 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/drm_fb_helper.c > > > b/drivers/gpu/drm/drm_fb_helper.c > > > index 64458982be40..6bb1b8b27d7a 100644 > > > --- a/drivers/gpu/drm/drm_fb_helper.c > > > +++ b/drivers/gpu/drm/drm_fb_helper.c > > > @@ -641,19 +641,27 @@ static void drm_fb_helper_damage(struct > > > drm_fb_helper *helper, u32 x, u32 y, > > > static void drm_fb_helper_memory_range_to_clip(struct fb_info > > > *info, off_t off, size_t len, > > > struct drm_rect *clip) > > > { > > > + u32 line_length = info->fix.line_length; > > > + u32 fb_height = info->var.yres; > > > off_t end = off + len; > > > u32 x1 = 0; > > > - u32 y1 = off / info->fix.line_length; > > > + u32 y1 = off / line_length; > > > u32 x2 = info->var.xres; > > > - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length); > > > + u32 y2 = DIV_ROUND_UP(end, line_length); > > > + > > > + /* Don't allow any of them beyond the bottom bound of display > > > area */ > > > + if (y1 > fb_height) > > > + y1 = fb_height; > > > + if (y2 > fb_height) > > > + y2 = fb_height; > > > if ((y2 - y1) == 1) { > > > /* > > > * We've only written to a single scanline. Try to reduce > > > * the number of horizontal pixels that need an update. > > > */ > > > - off_t bit_off = (off % info->fix.line_length) * 8; > > > - off_t bit_end = (end % info->fix.line_length) * 8; > > > + off_t bit_off = (off % line_length) * 8; > > > + off_t bit_end = (end % line_length) * 8; > > > > Please scratch all these changes. The current code should work as > > intended. Only the generic fbdev emulation uses this code and it should > > really be moved there at some point. > > > Are you meant that we should remove all these changes in > drivers/gpu/drm/drm_fb_helper.c ? > > > But this changes are helps to prevent the damage box computed go out of > bound, > > the bound of the displayable shadow buffer on multiple display case. > > It is the minimum width x height which could be fit in for all > display/minotor. > > > For example, one is 1920x1080 monitor, another is 1280x800 monitor. > > connected to the motherboard simultaneously. > > > Then, 1920x1080x4 (suppose we are using the XRGB) scanout buffer will be > > allocate by the GEM backend. But the the actual display area is 1280x800. > > This is true at least for my driver on my platform, In this case, > > ``` > > info->var.xres ==1280; > > info->var.yres == 800; > > ``` > > If don't restrict this, the damage box computed out of the bound of (0, 0) > ~ (1280, 800) rectangle. > > a 1920x1080 damage box will came out. > > > When running fbdev test of IGT, the smaller screen display will be OK. > > but the larger screen, the area outsize of 1280x800 will also be written. > > The background color became completely white from completely black before > carry out the test, > > luckily, linux kernel do not hung, this time. > > > On multi-screen case, we still need to restrict the damage box computed, > > Do not go out of 1280x800, right? > > > > > > > x1 = bit_off / info->var.bits_per_pixel; > > > x2 = DIV_ROUND_UP(bit_end, info->var.bits_per_pixel); > > > diff --git a/drivers/gpu/drm/drm_fbdev_generic.c > > > b/drivers/gpu/drm/drm_fbdev_generic.c > > > index 8e5148bf40bb..b057cfbba938 100644 > > > --- a/drivers/gpu/drm/drm_fbdev_generic.c > > > +++ b/drivers/gpu/drm/drm_fbdev_generic.c > > > @@ -94,7 +94,7 @@ static int > > > drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper, > > > fb_helper->buffer = buffer; > > > fb_helper->fb = buffer->fb; > > > - screen_size = buffer->gem->size; > > > + screen_size = sizes->surface_height * buffer->fb->pitches[0]; > > > > I guess we simply go back to this line. I'd R-b a patch that does > > exactly this. > > > > But some explanation is in order. Maybe you can add this as a comment to > > the computation, as it's not obvious: > > > > The value of screen_size should actually be the size of the gem buffer. > > In a physical framebuffer (i.e., video memory), the size would be a > > multiple of the page size, but not necessarily a multiple of the screen > > resolution. There are also pan fbdev's operations, and we could possibly > > use DRM buffers that are not multiples of the screen width. But the > > update code requires the use of drm_framebuffer_funcs.dirty, which takes > > a clipping rectangle and therefore doesn't work well with these odd > > values for screen_size. > > > > Best regards > > Thomas > > > > > screen_buffer = vzalloc(screen_size); > > > if (!screen_buffer) { > > > ret = -ENOMEM; > > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch