2017-04-07 20:03:35

by J. Neuschäfer

[permalink] [raw]
Subject: [PATCH] drm/udl: Fix unaligned memory access in udl_render_hline

On SPARC, the udl driver filled my kernel log with these messages:

[186668.910612] Kernel unaligned access at TPC[76609c] udl_render_hline+0x13c/0x3a0

Use put_unaligned_be16 to avoid them. On x86 this results in the same
code, but on SPARC the compiler emits two single-byte stores.

Signed-off-by: Jonathan Neuschäfer <[email protected]>
---
drivers/gpu/drm/udl/udl_transfer.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/udl/udl_transfer.c b/drivers/gpu/drm/udl/udl_transfer.c
index 917dcb978c2c..0c87b1ac6b68 100644
--- a/drivers/gpu/drm/udl/udl_transfer.c
+++ b/drivers/gpu/drm/udl/udl_transfer.c
@@ -14,6 +14,7 @@
#include <linux/slab.h>
#include <linux/fb.h>
#include <linux/prefetch.h>
+#include <asm/unaligned.h>

#include <drm/drmP.h>
#include "udl_drv.h"
@@ -163,7 +164,7 @@ static void udl_compress_hline16(
const u8 *const start = pixel;
const uint16_t repeating_pixel_val16 = pixel_val16;

- *(uint16_t *)cmd = cpu_to_be16(pixel_val16);
+ put_unaligned_be16(pixel_val16, cmd);

cmd += 2;
pixel += bpp;
--
2.11.0


2017-04-11 13:30:59

by Sean Paul

[permalink] [raw]
Subject: Re: [PATCH] drm/udl: Fix unaligned memory access in udl_render_hline

On Fri, Apr 07, 2017 at 10:02:29PM +0200, Jonathan Neusch?fer wrote:
> On SPARC, the udl driver filled my kernel log with these messages:
>
> [186668.910612] Kernel unaligned access at TPC[76609c] udl_render_hline+0x13c/0x3a0
>
> Use put_unaligned_be16 to avoid them. On x86 this results in the same
> code, but on SPARC the compiler emits two single-byte stores.
>

Pushed to drm-misc-fixes with Dave's IRC Ack.

Thanks,

Sean

> Signed-off-by: Jonathan Neusch?fer <[email protected]>
> ---
> drivers/gpu/drm/udl/udl_transfer.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/udl/udl_transfer.c b/drivers/gpu/drm/udl/udl_transfer.c
> index 917dcb978c2c..0c87b1ac6b68 100644
> --- a/drivers/gpu/drm/udl/udl_transfer.c
> +++ b/drivers/gpu/drm/udl/udl_transfer.c
> @@ -14,6 +14,7 @@
> #include <linux/slab.h>
> #include <linux/fb.h>
> #include <linux/prefetch.h>
> +#include <asm/unaligned.h>
>
> #include <drm/drmP.h>
> #include "udl_drv.h"
> @@ -163,7 +164,7 @@ static void udl_compress_hline16(
> const u8 *const start = pixel;
> const uint16_t repeating_pixel_val16 = pixel_val16;
>
> - *(uint16_t *)cmd = cpu_to_be16(pixel_val16);
> + put_unaligned_be16(pixel_val16, cmd);
>
> cmd += 2;
> pixel += bpp;
> --
> 2.11.0

--
Sean Paul, Software Engineer, Google / Chromium OS

2017-04-11 15:35:04

by J. Neuschäfer

[permalink] [raw]
Subject: Re: [PATCH] drm/udl: Fix unaligned memory access in udl_render_hline

On Tue, Apr 11, 2017 at 09:30:53AM -0400, Sean Paul wrote:
> On Fri, Apr 07, 2017 at 10:02:29PM +0200, Jonathan Neuschäfer wrote:
> > On SPARC, the udl driver filled my kernel log with these messages:
> >
> > [186668.910612] Kernel unaligned access at TPC[76609c] udl_render_hline+0x13c/0x3a0
> >
> > Use put_unaligned_be16 to avoid them. On x86 this results in the same
> > code, but on SPARC the compiler emits two single-byte stores.
> >
>
> Pushed to drm-misc-fixes with Dave's IRC Ack.
>
> Thanks,
>
> Sean

Thanks as well :-)


Jonathan


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