Re: [Intel-gfx] [PATCH] drm/modes: Prevent division by zero htotal
On Thu, Jan 24, 2019 at 07:11:53AM +, Zhang, Tina wrote: > > > > -Original Message- > > From: Daniel Vetter [mailto:daniel.vet...@ffwll.ch] On Behalf Of Daniel > > Vetter > > Sent: Wednesday, January 23, 2019 6:56 PM > > To: Zhang, Tina > > Cc: intel-gfx@lists.freedesktop.org; dri-de...@lists.freedesktop.org; Adam > > Jackson ; Dave Airlie ; Daniel Vetter > > > > Subject: Re: [PATCH] drm/modes: Prevent division by zero htotal > > > > On Wed, Jan 23, 2019 at 03:28:59PM +0800, Tina Zhang wrote: > > > This patch prevents division by zero htotal. > > > > How did you manage to get here with htotal == 0? This needs backtraces (or > > if > > this is just about static checkers, a mention of that). > > -Daniel > > In GVT-g, we are trying to enable a virtual display w/o setting timings for a > pipe > (a.k.a htotal=0), then we met the following kernel panic: > > [ 32.832048] divide error: [#1] SMP PTI > [ 32.833614] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.18.0-rc4-sriov+ #33 > [ 32.834438] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS > rel-1.10.1-0-g8891697-dirty-20180511_165818-tinazhang-linux-1 04/01/2014 > [ 32.835901] RIP: 0010:drm_mode_hsync+0x1e/0x40 > [ 32.836004] Code: 31 c0 c3 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 8b 87 > d8 00 00 00 85 c0 75 22 8b 4f 68 85 c9 78 1b 69 47 58 e8 03 00 00 99 f9 > b9 d3 4d 62 10 05 f4 01 00 00 f7 e1 89 d0 c1 e8 06 f3 c3 66 > [ 32.836004] RSP: :c90ebb90 EFLAGS: 00010206 > [ 32.836004] RAX: RBX: 88001c67c8a0 RCX: > > [ 32.836004] RDX: RSI: 88001c67c000 RDI: > 88001c67c8a0 > [ 32.836004] RBP: 88001c7d03a0 R08: 88001c67c8a0 R09: > 88001c7d0330 > [ 32.836004] R10: 822c3a98 R11: 0001 R12: > 88001c67c000 > [ 32.836004] R13: 88001c7d0370 R14: 8207eb78 R15: > 88001c67c800 > [ 32.836004] FS: () GS:88001da0() > knlGS: > [ 32.836004] CS: 0010 DS: ES: CR0: 80050033 > [ 32.836004] CR2: CR3: 0220a000 CR4: > 06f0 > [ 32.836004] DR0: DR1: DR2: > > [ 32.836004] DR3: DR6: fffe0ff0 DR7: > 0400 > [ 32.836004] Call Trace: > [ 32.836004] intel_mode_from_pipe_config+0x72/0x90 > [ 32.836004] intel_modeset_setup_hw_state+0x569/0xf90 > [ 32.836004] intel_modeset_init+0x905/0x1db0 > [ 32.836004] i915_driver_load+0xb8c/0x1120 > [ 32.836004] i915_pci_probe+0x4d/0xb0 > [ 32.836004] local_pci_probe+0x44/0xa0 > [ 32.836004] ? pci_assign_irq+0x27/0x130 > [ 32.836004] pci_device_probe+0x102/0x1c0 > [ 32.836004] driver_probe_device+0x2b8/0x480 > [ 32.836004] __driver_attach+0x109/0x110 > [ 32.836004] ? driver_probe_device+0x480/0x480 > [ 32.836004] bus_for_each_dev+0x67/0xc0 > [ 32.836004] ? klist_add_tail+0x3b/0x70 > [ 32.836004] bus_add_driver+0x1e8/0x260 > [ 32.836004] driver_register+0x5b/0xe0 > [ 32.836004] ? mipi_dsi_bus_init+0x11/0x11 > [ 32.836004] do_one_initcall+0x4d/0x1eb > [ 32.836004] kernel_init_freeable+0x197/0x237 > [ 32.836004] ? rest_init+0xd0/0xd0 > [ 32.836004] kernel_init+0xa/0x110 > [ 32.836004] ret_from_fork+0x35/0x40 > [ 32.836004] Modules linked in: > [ 32.859183] ---[ end trace 525608b0ed0e8665 ]--- > [ 32.859722] RIP: 0010:drm_mode_hsync+0x1e/0x40 > [ 32.860287] Code: 31 c0 c3 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 8b 87 > d8 00 00 00 85 c0 75 22 8b 4f 68 85 c9 78 1b 69 47 58 e8 03 00 00 99 f9 > b9 d3 4d 62 10 05 f4 01 00 00 f7 e1 89 d0 c1 e8 06 f3 c3 66 > [ 32.862680] RSP: :c90ebb90 EFLAGS: 00010206 > [ 32.863309] RAX: RBX: 88001c67c8a0 RCX: > > [ 32.864182] RDX: RSI: 88001c67c000 RDI: > 88001c67c8a0 > [ 32.865206] RBP: 88001c7d03a0 R08: 88001c67c8a0 R09: > 88001c7d0330 > [ 32.866359] R10: 822c3a98 R11: 0001 R12: > 88001c67c000 > [ 32.867213] R13: 88001c7d0370 R14: 8207eb78 R15: > 88001c67c800 > [ 32.868075] FS: () GS:88001da0() > knlGS: > [ 32.868983] CS: 0010 DS: ES: CR0: 80050033 > [ 32.869659] CR2: CR3: 0220a000 CR4: > 06f0 > [ 32.870599] DR0: DR1: DR2: > > [ 32.871598] DR3: DR6: fffe0ff0 DR7: > 0400 > [ 32.872549] Kernel panic - not syncing: Attempted to kill init! > exitcode=0x000b > > Since drm_mode_hsync() has the logic to check mode->htotal, I just extend it > to cover the case htotal==0. Hm ok, makes sense. And drm_mode_vrefresh also has that check. I'll add your backtrace and merge the patch. Thanks, Daniel > > Thanks. > > BR, > Tina
Re: [Intel-gfx] [PATCH] drm/modes: Prevent division by zero htotal
> -Original Message- > From: Daniel Vetter [mailto:daniel.vet...@ffwll.ch] On Behalf Of Daniel Vetter > Sent: Wednesday, January 23, 2019 6:56 PM > To: Zhang, Tina > Cc: intel-gfx@lists.freedesktop.org; dri-de...@lists.freedesktop.org; Adam > Jackson ; Dave Airlie ; Daniel Vetter > > Subject: Re: [PATCH] drm/modes: Prevent division by zero htotal > > On Wed, Jan 23, 2019 at 03:28:59PM +0800, Tina Zhang wrote: > > This patch prevents division by zero htotal. > > How did you manage to get here with htotal == 0? This needs backtraces (or if > this is just about static checkers, a mention of that). > -Daniel In GVT-g, we are trying to enable a virtual display w/o setting timings for a pipe (a.k.a htotal=0), then we met the following kernel panic: [ 32.832048] divide error: [#1] SMP PTI [ 32.833614] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.18.0-rc4-sriov+ #33 [ 32.834438] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.10.1-0-g8891697-dirty-20180511_165818-tinazhang-linux-1 04/01/2014 [ 32.835901] RIP: 0010:drm_mode_hsync+0x1e/0x40 [ 32.836004] Code: 31 c0 c3 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 8b 87 d8 00 00 00 85 c0 75 22 8b 4f 68 85 c9 78 1b 69 47 58 e8 03 00 00 99 f9 b9 d3 4d 62 10 05 f4 01 00 00 f7 e1 89 d0 c1 e8 06 f3 c3 66 [ 32.836004] RSP: :c90ebb90 EFLAGS: 00010206 [ 32.836004] RAX: RBX: 88001c67c8a0 RCX: [ 32.836004] RDX: RSI: 88001c67c000 RDI: 88001c67c8a0 [ 32.836004] RBP: 88001c7d03a0 R08: 88001c67c8a0 R09: 88001c7d0330 [ 32.836004] R10: 822c3a98 R11: 0001 R12: 88001c67c000 [ 32.836004] R13: 88001c7d0370 R14: 8207eb78 R15: 88001c67c800 [ 32.836004] FS: () GS:88001da0() knlGS: [ 32.836004] CS: 0010 DS: ES: CR0: 80050033 [ 32.836004] CR2: CR3: 0220a000 CR4: 06f0 [ 32.836004] DR0: DR1: DR2: [ 32.836004] DR3: DR6: fffe0ff0 DR7: 0400 [ 32.836004] Call Trace: [ 32.836004] intel_mode_from_pipe_config+0x72/0x90 [ 32.836004] intel_modeset_setup_hw_state+0x569/0xf90 [ 32.836004] intel_modeset_init+0x905/0x1db0 [ 32.836004] i915_driver_load+0xb8c/0x1120 [ 32.836004] i915_pci_probe+0x4d/0xb0 [ 32.836004] local_pci_probe+0x44/0xa0 [ 32.836004] ? pci_assign_irq+0x27/0x130 [ 32.836004] pci_device_probe+0x102/0x1c0 [ 32.836004] driver_probe_device+0x2b8/0x480 [ 32.836004] __driver_attach+0x109/0x110 [ 32.836004] ? driver_probe_device+0x480/0x480 [ 32.836004] bus_for_each_dev+0x67/0xc0 [ 32.836004] ? klist_add_tail+0x3b/0x70 [ 32.836004] bus_add_driver+0x1e8/0x260 [ 32.836004] driver_register+0x5b/0xe0 [ 32.836004] ? mipi_dsi_bus_init+0x11/0x11 [ 32.836004] do_one_initcall+0x4d/0x1eb [ 32.836004] kernel_init_freeable+0x197/0x237 [ 32.836004] ? rest_init+0xd0/0xd0 [ 32.836004] kernel_init+0xa/0x110 [ 32.836004] ret_from_fork+0x35/0x40 [ 32.836004] Modules linked in: [ 32.859183] ---[ end trace 525608b0ed0e8665 ]--- [ 32.859722] RIP: 0010:drm_mode_hsync+0x1e/0x40 [ 32.860287] Code: 31 c0 c3 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 8b 87 d8 00 00 00 85 c0 75 22 8b 4f 68 85 c9 78 1b 69 47 58 e8 03 00 00 99 f9 b9 d3 4d 62 10 05 f4 01 00 00 f7 e1 89 d0 c1 e8 06 f3 c3 66 [ 32.862680] RSP: :c90ebb90 EFLAGS: 00010206 [ 32.863309] RAX: RBX: 88001c67c8a0 RCX: [ 32.864182] RDX: RSI: 88001c67c000 RDI: 88001c67c8a0 [ 32.865206] RBP: 88001c7d03a0 R08: 88001c67c8a0 R09: 88001c7d0330 [ 32.866359] R10: 822c3a98 R11: 0001 R12: 88001c67c000 [ 32.867213] R13: 88001c7d0370 R14: 8207eb78 R15: 88001c67c800 [ 32.868075] FS: () GS:88001da0() knlGS: [ 32.868983] CS: 0010 DS: ES: CR0: 80050033 [ 32.869659] CR2: CR3: 0220a000 CR4: 06f0 [ 32.870599] DR0: DR1: DR2: [ 32.871598] DR3: DR6: fffe0ff0 DR7: 0400 [ 32.872549] Kernel panic - not syncing: Attempted to kill init! exitcode=0x000b Since drm_mode_hsync() has the logic to check mode->htotal, I just extend it to cover the case htotal==0. Thanks. BR, Tina > > > > > Signed-off-by: Tina Zhang > > Cc: Adam Jackson > > Cc: Dave Airlie > > Cc: Daniel Vetter > > --- > > drivers/gpu/drm/drm_modes.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c > > index adce9a2..59b92b1 100644 > > --- a/drivers/gpu/drm/drm_modes.c > > +++ b/drivers/gpu/drm/drm_modes.c > > @@ -751,7 +751,7 @@ int
Re: [Intel-gfx] [PATCH] drm/modes: Prevent division by zero htotal
On Wed, Jan 23, 2019 at 03:28:59PM +0800, Tina Zhang wrote: > This patch prevents division by zero htotal. How did you manage to get here with htotal == 0? This needs backtraces (or if this is just about static checkers, a mention of that). -Daniel > > Signed-off-by: Tina Zhang > Cc: Adam Jackson > Cc: Dave Airlie > Cc: Daniel Vetter > --- > drivers/gpu/drm/drm_modes.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c > index adce9a2..59b92b1 100644 > --- a/drivers/gpu/drm/drm_modes.c > +++ b/drivers/gpu/drm/drm_modes.c > @@ -751,7 +751,7 @@ int drm_mode_hsync(const struct drm_display_mode *mode) > if (mode->hsync) > return mode->hsync; > > - if (mode->htotal < 0) > + if (mode->htotal <= 0) > return 0; > > calc_val = (mode->clock * 1000) / mode->htotal; /* hsync in Hz */ > -- > 2.7.4 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch ___ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
[Intel-gfx] [PATCH] drm/modes: Prevent division by zero htotal
This patch prevents division by zero htotal. Signed-off-by: Tina Zhang Cc: Adam Jackson Cc: Dave Airlie Cc: Daniel Vetter --- drivers/gpu/drm/drm_modes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c index adce9a2..59b92b1 100644 --- a/drivers/gpu/drm/drm_modes.c +++ b/drivers/gpu/drm/drm_modes.c @@ -751,7 +751,7 @@ int drm_mode_hsync(const struct drm_display_mode *mode) if (mode->hsync) return mode->hsync; - if (mode->htotal < 0) + if (mode->htotal <= 0) return 0; calc_val = (mode->clock * 1000) / mode->htotal; /* hsync in Hz */ -- 2.7.4 ___ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
