drivers/media/v4l2-core/v4l2-ioctl.c:303:28: warning: taking address of packed member 'pixelformat' of class or structure 'v4l2_pix_format_mplane' may result in an unaligned pointer value
9:33 p.m.
Hi Sakari,
FYI, the error/warning still remains.
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: d1587f7bfe9a0f97a75d42ac1489aeda551106bc
commit: e927e1e0f0dd3e353d5556503a71484008692c82 v4l: ioctl: Use %p4cc printk modifier to
print FourCC codes
date: 11 months ago
config: mips-buildonly-randconfig-r002-20220107
(https://download.01.org/0day-ci/archive/20220108/202201081852.uTfBqS4b-lk...)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
32167bfe64a4c5dd4eb3f7a58e24f4cba76f5ac2)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
chmod +x ~/bin/make.cross
# install mips cross compiling tool for clang build
# apt-get install binutils-mips-linux-gnu
#
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit...
git remote add linus
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout e927e1e0f0dd3e353d5556503a71484008692c82
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir
ARCH=mips SHELL=/bin/bash drivers/hid/ drivers/media/v4l2-core/ fs/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp(a)intel.com>
All warnings (new ones prefixed by >>):
> drivers/media/v4l2-core/v4l2-ioctl.c:303:28: warning: taking
address of packed member 'pixelformat' of class or structure
'v4l2_pix_format_mplane' may result in an unaligned pointer value
[-Waddress-of-packed-member]
mp->width, mp->height,
&mp->pixelformat,
^~~~~~~~~~~~~~~
include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
printk(KERN_CONT fmt, ##__VA_ARGS__)
^~~~~~~~~~~
> drivers/media/v4l2-core/v4l2-ioctl.c:347:37: warning: taking
address of packed member 'pixelformat' of class or structure
'v4l2_sdr_format' may result in an unaligned pointer value
[-Waddress-of-packed-member]
pr_cont(",
pixelformat=%p4cc\n", &sdr->pixelformat);
^~~~~~~~~~~~~~~~
include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
printk(KERN_CONT fmt, ##__VA_ARGS__)
^~~~~~~~~~~
> drivers/media/v4l2-core/v4l2-ioctl.c:353:5: warning: taking
address of packed member 'dataformat' of class or structure
'v4l2_meta_format' may result in an unaligned pointer value
[-Waddress-of-packed-member]
&meta->dataformat,
meta->buffersize);
^~~~~~~~~~~~~~~~
include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
printk(KERN_CONT fmt, ##__VA_ARGS__)
^~~~~~~~~~~
3 warnings generated.
vim +303 drivers/media/v4l2-core/v4l2-ioctl.c
273
274 static void v4l_print_format(const void *arg, bool write_only)
275 {
276 const struct v4l2_format *p = arg;
277 const struct v4l2_pix_format *pix;
278 const struct v4l2_pix_format_mplane *mp;
279 const struct v4l2_vbi_format *vbi;
280 const struct v4l2_sliced_vbi_format *sliced;
281 const struct v4l2_window *win;
282 const struct v4l2_sdr_format *sdr;
283 const struct v4l2_meta_format *meta;
284 u32 planes;
285 unsigned i;
286
287 pr_cont("type=%s", prt_names(p->type, v4l2_type_names));
288 switch (p->type) {
289 case V4L2_BUF_TYPE_VIDEO_CAPTURE:
290 case V4L2_BUF_TYPE_VIDEO_OUTPUT:
291 pix = &p->fmt.pix;
292 pr_cont(", width=%u, height=%u, pixelformat=%p4cc, field=%s,
bytesperline=%u, sizeimage=%u, colorspace=%d, flags=0x%x, ycbcr_enc=%u, quantization=%u,
xfer_func=%u\n",
293 pix->width, pix->height, &pix->pixelformat,
294 prt_names(pix->field, v4l2_field_names),
295 pix->bytesperline, pix->sizeimage,
296 pix->colorspace, pix->flags, pix->ycbcr_enc,
297 pix->quantization, pix->xfer_func);
298 break;
299 case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
300 case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:
301 mp = &p->fmt.pix_mp;
302 pr_cont(", width=%u, height=%u, format=%p4cc, field=%s, colorspace=%d,
num_planes=%u, flags=0x%x, ycbcr_enc=%u, quantization=%u, xfer_func=%u\n",
303 mp->width, mp->height, &mp->pixelformat,
304 prt_names(mp->field, v4l2_field_names),
305 mp->colorspace, mp->num_planes, mp->flags,
306 mp->ycbcr_enc, mp->quantization, mp->xfer_func);
307 planes = min_t(u32, mp->num_planes, VIDEO_MAX_PLANES);
308 for (i = 0; i < planes; i++)
309 printk(KERN_DEBUG "plane %u: bytesperline=%u sizeimage=%u\n", i,
310 mp->plane_fmt[i].bytesperline,
311 mp->plane_fmt[i].sizeimage);
312 break;
313 case V4L2_BUF_TYPE_VIDEO_OVERLAY:
314 case V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY:
315 win = &p->fmt.win;
316 /* Note: we can't print the clip list here since the clips
317 * pointer is a userspace pointer, not a kernelspace
318 * pointer. */
319 pr_cont(", wxh=%dx%d, x,y=%d,%d, field=%s, chromakey=0x%08x, clipcount=%u,
clips=%p, bitmap=%p, global_alpha=0x%02x\n",
320 win->w.width, win->w.height, win->w.left, win->w.top,
321 prt_names(win->field, v4l2_field_names),
322 win->chromakey, win->clipcount, win->clips,
323 win->bitmap, win->global_alpha);
324 break;
325 case V4L2_BUF_TYPE_VBI_CAPTURE:
326 case V4L2_BUF_TYPE_VBI_OUTPUT:
327 vbi = &p->fmt.vbi;
328 pr_cont(", sampling_rate=%u, offset=%u, samples_per_line=%u,
sample_format=%p4cc, start=%u,%u, count=%u,%u\n",
329 vbi->sampling_rate, vbi->offset,
330 vbi->samples_per_line, &vbi->sample_format,
331 vbi->start[0], vbi->start[1],
332 vbi->count[0], vbi->count[1]);
333 break;
334 case V4L2_BUF_TYPE_SLICED_VBI_CAPTURE:
335 case V4L2_BUF_TYPE_SLICED_VBI_OUTPUT:
336 sliced = &p->fmt.sliced;
337 pr_cont(", service_set=0x%08x, io_size=%d\n",
338 sliced->service_set, sliced->io_size);
339 for (i = 0; i < 24; i++)
340 printk(KERN_DEBUG "line[%02u]=0x%04x, 0x%04x\n", i,
341 sliced->service_lines[0][i],
342 sliced->service_lines[1][i]);
343 break;
344 case V4L2_BUF_TYPE_SDR_CAPTURE:
345 case V4L2_BUF_TYPE_SDR_OUTPUT:
346 sdr = &p->fmt.sdr;
347 pr_cont(", pixelformat=%p4cc\n",
&sdr->pixelformat);
348 break;
349 case V4L2_BUF_TYPE_META_CAPTURE:
350 case V4L2_BUF_TYPE_META_OUTPUT:
351 meta = &p->fmt.meta;
352 pr_cont(", dataformat=%p4cc, buffersize=%u\n",
353 &meta->dataformat, meta->buffersize);
354 break;
355 }
356 }
357
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
1:26 a.m.
+Nick Desaulniers
Any ideas on how to fix this?
On Sun, Jan 9, 2022 at 3:53 PM kernel test robot <lkp(a)intel.com> wrote:
Hi Sakari,
FYI, the error/warning still remains.
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: d1587f7bfe9a0f97a75d42ac1489aeda551106bc
commit: e927e1e0f0dd3e353d5556503a71484008692c82 v4l: ioctl: Use %p4cc printk modifier to
print FourCC codes
date: 11 months ago
config: mips-buildonly-randconfig-r002-20220107
(https://download.01.org/0day-ci/archive/20220108/202201081852.uTfBqS4b-lk...)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
32167bfe64a4c5dd4eb3f7a58e24f4cba76f5ac2)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
chmod +x ~/bin/make.cross
# install mips cross compiling tool for clang build
# apt-get install binutils-mips-linux-gnu
#
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit...
git remote add linus
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout e927e1e0f0dd3e353d5556503a71484008692c82
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir
ARCH=mips SHELL=/bin/bash drivers/hid/ drivers/media/v4l2-core/ fs/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp(a)intel.com>
All warnings (new ones prefixed by >>):
>> drivers/media/v4l2-core/v4l2-ioctl.c:303:28: warning: taking address of packed
member 'pixelformat' of class or structure 'v4l2_pix_format_mplane' may
result in an unaligned pointer value [-Waddress-of-packed-member]
mp->width, mp->height, &mp->pixelformat,
^~~~~~~~~~~~~~~
include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
printk(KERN_CONT fmt, ##__VA_ARGS__)
^~~~~~~~~~~
>> drivers/media/v4l2-core/v4l2-ioctl.c:347:37: warning: taking address of packed
member 'pixelformat' of class or structure 'v4l2_sdr_format' may result in
an unaligned pointer value [-Waddress-of-packed-member]
pr_cont(", pixelformat=%p4cc\n", &sdr->pixelformat);
^~~~~~~~~~~~~~~~
include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
printk(KERN_CONT fmt, ##__VA_ARGS__)
^~~~~~~~~~~
>> drivers/media/v4l2-core/v4l2-ioctl.c:353:5: warning: taking address of packed
member 'dataformat' of class or structure 'v4l2_meta_format' may result in
an unaligned pointer value [-Waddress-of-packed-member]
&meta->dataformat, meta->buffersize);
^~~~~~~~~~~~~~~~
include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
printk(KERN_CONT fmt, ##__VA_ARGS__)
^~~~~~~~~~~
3 warnings generated.
vim +303 drivers/media/v4l2-core/v4l2-ioctl.c
273
274 static void v4l_print_format(const void *arg, bool write_only)
275 {
276 const struct v4l2_format *p = arg;
277 const struct v4l2_pix_format *pix;
278 const struct v4l2_pix_format_mplane *mp;
279 const struct v4l2_vbi_format *vbi;
280 const struct v4l2_sliced_vbi_format *sliced;
281 const struct v4l2_window *win;
282 const struct v4l2_sdr_format *sdr;
283 const struct v4l2_meta_format *meta;
284 u32 planes;
285 unsigned i;
286
287 pr_cont("type=%s", prt_names(p->type, v4l2_type_names));
288 switch (p->type) {
289 case V4L2_BUF_TYPE_VIDEO_CAPTURE:
290 case V4L2_BUF_TYPE_VIDEO_OUTPUT:
291 pix = &p->fmt.pix;
292 pr_cont(", width=%u, height=%u, pixelformat=%p4cc, field=%s,
bytesperline=%u, sizeimage=%u, colorspace=%d, flags=0x%x, ycbcr_enc=%u, quantization=%u,
xfer_func=%u\n",
293 pix->width, pix->height, &pix->pixelformat,
294 prt_names(pix->field, v4l2_field_names),
295 pix->bytesperline, pix->sizeimage,
296 pix->colorspace, pix->flags, pix->ycbcr_enc,
297 pix->quantization, pix->xfer_func);
298 break;
299 case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
300 case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:
301 mp = &p->fmt.pix_mp;
302 pr_cont(", width=%u, height=%u, format=%p4cc, field=%s,
colorspace=%d, num_planes=%u, flags=0x%x, ycbcr_enc=%u, quantization=%u,
xfer_func=%u\n",
> 303 mp->width, mp->height, &mp->pixelformat,
304 prt_names(mp->field, v4l2_field_names),
305 mp->colorspace, mp->num_planes, mp->flags,
306 mp->ycbcr_enc, mp->quantization,
mp->xfer_func);
307 planes = min_t(u32, mp->num_planes, VIDEO_MAX_PLANES);
308 for (i = 0; i < planes; i++)
309 printk(KERN_DEBUG "plane %u: bytesperline=%u
sizeimage=%u\n", i,
310 mp->plane_fmt[i].bytesperline,
311 mp->plane_fmt[i].sizeimage);
312 break;
313 case V4L2_BUF_TYPE_VIDEO_OVERLAY:
314 case V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY:
315 win = &p->fmt.win;
316 /* Note: we can't print the clip list here since the clips
317 * pointer is a userspace pointer, not a kernelspace
318 * pointer. */
319 pr_cont(", wxh=%dx%d, x,y=%d,%d, field=%s, chromakey=0x%08x,
clipcount=%u, clips=%p, bitmap=%p, global_alpha=0x%02x\n",
320 win->w.width, win->w.height, win->w.left,
win->w.top,
321 prt_names(win->field, v4l2_field_names),
322 win->chromakey, win->clipcount, win->clips,
323 win->bitmap, win->global_alpha);
324 break;
325 case V4L2_BUF_TYPE_VBI_CAPTURE:
326 case V4L2_BUF_TYPE_VBI_OUTPUT:
327 vbi = &p->fmt.vbi;
328 pr_cont(", sampling_rate=%u, offset=%u, samples_per_line=%u,
sample_format=%p4cc, start=%u,%u, count=%u,%u\n",
329 vbi->sampling_rate, vbi->offset,
330 vbi->samples_per_line, &vbi->sample_format,
331 vbi->start[0], vbi->start[1],
332 vbi->count[0], vbi->count[1]);
333 break;
334 case V4L2_BUF_TYPE_SLICED_VBI_CAPTURE:
335 case V4L2_BUF_TYPE_SLICED_VBI_OUTPUT:
336 sliced = &p->fmt.sliced;
337 pr_cont(", service_set=0x%08x, io_size=%d\n",
338 sliced->service_set, sliced->io_size);
339 for (i = 0; i < 24; i++)
340 printk(KERN_DEBUG "line[%02u]=0x%04x,
0x%04x\n", i,
341 sliced->service_lines[0][i],
342 sliced->service_lines[1][i]);
343 break;
344 case V4L2_BUF_TYPE_SDR_CAPTURE:
345 case V4L2_BUF_TYPE_SDR_OUTPUT:
346 sdr = &p->fmt.sdr;
> 347 pr_cont(", pixelformat=%p4cc\n",
&sdr->pixelformat);
348 break;
349 case V4L2_BUF_TYPE_META_CAPTURE:
350 case V4L2_BUF_TYPE_META_OUTPUT:
351 meta = &p->fmt.meta;
352 pr_cont(", dataformat=%p4cc, buffersize=%u\n",
> 353 &meta->dataformat, meta->buffersize);
354 break;
355 }
356 }
357
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
--
With Best Regards,
Andy Shevchenko
6:44 a.m.
On Sun, Jan 9, 2022 at 6:26 AM Andy Shevchenko
<andy.shevchenko(a)gmail.com> wrote:
+Nick Desaulniers
Any ideas on how to fix this?
Not obviously. This code probably will trigger a splat when run with
UBSan though.
I'm curious if the structure needs to be packed for interfacing with
hardware or some ABI, or whether we could add an explicit alignment to
the member if that would be ok (which may add back some padding)?
Otherwise, I suspect to actually access this properly we may have
macros for performing underaligned loads and stores? I suspect you'd
read potentially unaligned data into an aligned copy, then do
operations on that, at which point printing the address of the copy is
legal, but perhaps useless.
Perhaps:
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index df8b9c486ba1..3bb8d7aaba8a 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -2293,7 +2293,7 @@ struct v4l2_plane_pix_format {
struct v4l2_pix_format_mplane {
__u32 width;
__u32 height;
- __u32 pixelformat;
+ __u32 pixelformat __aligned(4);
__u32 field;
__u32 colorspace;
Perhaps we could tighten up this warning in clang; we don't have any
holes before this member, so I _wouldn't_ have assumed
__attribute__((packed)) would have caused the address of pixelformat
member of an instance of struct v4l2_pix_format_mplane to ever be
underaligned.
On Sun, Jan 9, 2022 at 3:53 PM kernel test robot <lkp(a)intel.com> wrote:
>
> Hi Sakari,
>
> FYI, the error/warning still remains.
>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: d1587f7bfe9a0f97a75d42ac1489aeda551106bc
> commit: e927e1e0f0dd3e353d5556503a71484008692c82 v4l: ioctl: Use %p4cc printk
modifier to print FourCC codes
> date: 11 months ago
> config: mips-buildonly-randconfig-r002-20220107
(https://download.01.org/0day-ci/archive/20220108/202201081852.uTfBqS4b-lk...)
> compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
32167bfe64a4c5dd4eb3f7a58e24f4cba76f5ac2)
> reproduce (this is a W=1 build):
> wget
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
> chmod +x ~/bin/make.cross
> # install mips cross compiling tool for clang build
> # apt-get install binutils-mips-linux-gnu
> #
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit...
> git remote add linus
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> git fetch --no-tags linus master
> git checkout e927e1e0f0dd3e353d5556503a71484008692c82
> # save the config file to linux build tree
> mkdir build_dir
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir
ARCH=mips SHELL=/bin/bash drivers/hid/ drivers/media/v4l2-core/ fs/
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp(a)intel.com>
>
> All warnings (new ones prefixed by >>):
>
> >> drivers/media/v4l2-core/v4l2-ioctl.c:303:28: warning: taking address of
packed member 'pixelformat' of class or structure 'v4l2_pix_format_mplane'
may result in an unaligned pointer value [-Waddress-of-packed-member]
> mp->width, mp->height, &mp->pixelformat,
> ^~~~~~~~~~~~~~~
> include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
> printk(KERN_CONT fmt, ##__VA_ARGS__)
> ^~~~~~~~~~~
> >> drivers/media/v4l2-core/v4l2-ioctl.c:347:37: warning: taking address of
packed member 'pixelformat' of class or structure 'v4l2_sdr_format' may
result in an unaligned pointer value [-Waddress-of-packed-member]
> pr_cont(", pixelformat=%p4cc\n",
&sdr->pixelformat);
> ^~~~~~~~~~~~~~~~
> include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
> printk(KERN_CONT fmt, ##__VA_ARGS__)
> ^~~~~~~~~~~
> >> drivers/media/v4l2-core/v4l2-ioctl.c:353:5: warning: taking address of
packed member 'dataformat' of class or structure 'v4l2_meta_format' may
result in an unaligned pointer value [-Waddress-of-packed-member]
> &meta->dataformat, meta->buffersize);
> ^~~~~~~~~~~~~~~~
> include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
> printk(KERN_CONT fmt, ##__VA_ARGS__)
> ^~~~~~~~~~~
> 3 warnings generated.
>
>
> vim +303 drivers/media/v4l2-core/v4l2-ioctl.c
>
> 273
> 274 static void v4l_print_format(const void *arg, bool write_only)
> 275 {
> 276 const struct v4l2_format *p = arg;
> 277 const struct v4l2_pix_format *pix;
> 278 const struct v4l2_pix_format_mplane *mp;
> 279 const struct v4l2_vbi_format *vbi;
> 280 const struct v4l2_sliced_vbi_format *sliced;
> 281 const struct v4l2_window *win;
> 282 const struct v4l2_sdr_format *sdr;
> 283 const struct v4l2_meta_format *meta;
> 284 u32 planes;
> 285 unsigned i;
> 286
> 287 pr_cont("type=%s", prt_names(p->type,
v4l2_type_names));
> 288 switch (p->type) {
> 289 case V4L2_BUF_TYPE_VIDEO_CAPTURE:
> 290 case V4L2_BUF_TYPE_VIDEO_OUTPUT:
> 291 pix = &p->fmt.pix;
> 292 pr_cont(", width=%u, height=%u, pixelformat=%p4cc,
field=%s, bytesperline=%u, sizeimage=%u, colorspace=%d, flags=0x%x, ycbcr_enc=%u,
quantization=%u, xfer_func=%u\n",
> 293 pix->width, pix->height,
&pix->pixelformat,
> 294 prt_names(pix->field, v4l2_field_names),
> 295 pix->bytesperline, pix->sizeimage,
> 296 pix->colorspace, pix->flags,
pix->ycbcr_enc,
> 297 pix->quantization, pix->xfer_func);
> 298 break;
> 299 case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
> 300 case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:
> 301 mp = &p->fmt.pix_mp;
> 302 pr_cont(", width=%u, height=%u, format=%p4cc, field=%s,
colorspace=%d, num_planes=%u, flags=0x%x, ycbcr_enc=%u, quantization=%u,
xfer_func=%u\n",
> > 303 mp->width, mp->height,
&mp->pixelformat,
> 304 prt_names(mp->field, v4l2_field_names),
> 305 mp->colorspace, mp->num_planes, mp->flags,
> 306 mp->ycbcr_enc, mp->quantization,
mp->xfer_func);
> 307 planes = min_t(u32, mp->num_planes, VIDEO_MAX_PLANES);
> 308 for (i = 0; i < planes; i++)
> 309 printk(KERN_DEBUG "plane %u: bytesperline=%u
sizeimage=%u\n", i,
> 310 mp->plane_fmt[i].bytesperline,
> 311 mp->plane_fmt[i].sizeimage);
> 312 break;
> 313 case V4L2_BUF_TYPE_VIDEO_OVERLAY:
> 314 case V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY:
> 315 win = &p->fmt.win;
> 316 /* Note: we can't print the clip list here since the
clips
> 317 * pointer is a userspace pointer, not a kernelspace
> 318 * pointer. */
> 319 pr_cont(", wxh=%dx%d, x,y=%d,%d, field=%s,
chromakey=0x%08x, clipcount=%u, clips=%p, bitmap=%p, global_alpha=0x%02x\n",
> 320 win->w.width, win->w.height, win->w.left,
win->w.top,
> 321 prt_names(win->field, v4l2_field_names),
> 322 win->chromakey, win->clipcount,
win->clips,
> 323 win->bitmap, win->global_alpha);
> 324 break;
> 325 case V4L2_BUF_TYPE_VBI_CAPTURE:
> 326 case V4L2_BUF_TYPE_VBI_OUTPUT:
> 327 vbi = &p->fmt.vbi;
> 328 pr_cont(", sampling_rate=%u, offset=%u,
samples_per_line=%u, sample_format=%p4cc, start=%u,%u, count=%u,%u\n",
> 329 vbi->sampling_rate, vbi->offset,
> 330 vbi->samples_per_line,
&vbi->sample_format,
> 331 vbi->start[0], vbi->start[1],
> 332 vbi->count[0], vbi->count[1]);
> 333 break;
> 334 case V4L2_BUF_TYPE_SLICED_VBI_CAPTURE:
> 335 case V4L2_BUF_TYPE_SLICED_VBI_OUTPUT:
> 336 sliced = &p->fmt.sliced;
> 337 pr_cont(", service_set=0x%08x, io_size=%d\n",
> 338 sliced->service_set,
sliced->io_size);
> 339 for (i = 0; i < 24; i++)
> 340 printk(KERN_DEBUG "line[%02u]=0x%04x,
0x%04x\n", i,
> 341 sliced->service_lines[0][i],
> 342 sliced->service_lines[1][i]);
> 343 break;
> 344 case V4L2_BUF_TYPE_SDR_CAPTURE:
> 345 case V4L2_BUF_TYPE_SDR_OUTPUT:
> 346 sdr = &p->fmt.sdr;
> > 347 pr_cont(", pixelformat=%p4cc\n",
&sdr->pixelformat);
> 348 break;
> 349 case V4L2_BUF_TYPE_META_CAPTURE:
> 350 case V4L2_BUF_TYPE_META_OUTPUT:
> 351 meta = &p->fmt.meta;
> 352 pr_cont(", dataformat=%p4cc, buffersize=%u\n",
> > 353 &meta->dataformat, meta->buffersize);
> 354 break;
> 355 }
> 356 }
> 357
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
--
With Best Regards,
Andy Shevchenko
--
Thanks,
~Nick Desaulniers
7:49 a.m.
On Mon, Jan 10, 2022 at 11:44:12AM -0800, Nick Desaulniers wrote:
On Sun, Jan 9, 2022 at 6:26 AM Andy Shevchenko
<andy.shevchenko(a)gmail.com> wrote:
>
> +Nick Desaulniers
>
> Any ideas on how to fix this?
Not obviously.
Thanks for looking into this!
This code probably will trigger a splat when run with
UBSan though.
I'm curious if the structure needs to be packed for interfacing with
hardware or some ABI, or whether we could add an explicit alignment to
the member if that would be ok (which may add back some padding)?
Looking into it I think removing packed attribute brings a regression
immediately on 64-bit platforms since u32 member followed by u8.
Otherwise, I suspect to actually access this properly we may have
macros for performing underaligned loads and stores? I suspect you'd
read potentially unaligned data into an aligned copy, then do
operations on that, at which point printing the address of the copy is
legal, but perhaps useless.
Current code does this:
val = *fourcc & ~BIT(31);
...
for (i = 0; i < sizeof(*fourcc); i++) {
...
strcpy(p, *fourcc & BIT(31) ? " big-endian" : " little-endian");
...
p = special_hex_number(p, output + sizeof(output) - 2, *fourcc, sizeof(u32));
If unaligned access is not good it will crash on some architectures AFAIU.
So, it should use get_unaligned() in the first place.
Perhaps:
- __u32 pixelformat;
+ __u32 pixelformat __aligned(4);
This looks weird, however I can't immediately see any side effects of it.
What if the address of the entire structure is unaligned, would we have a
gap here? In any case I wouldn't go this way.
__u32 field;
__u32 colorspace;
Perhaps we could tighten up this warning in clang; we don't have any
holes before this member, so I _wouldn't_ have assumed
__attribute__((packed)) would have caused the address of pixelformat
member of an instance of struct v4l2_pix_format_mplane to ever be
underaligned.
> On Sun, Jan 9, 2022 at 3:53 PM kernel test robot <lkp(a)intel.com> wrote:
> >
> > Hi Sakari,
> >
> > FYI, the error/warning still remains.
> >
> > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
master
> > head: d1587f7bfe9a0f97a75d42ac1489aeda551106bc
> > commit: e927e1e0f0dd3e353d5556503a71484008692c82 v4l: ioctl: Use %p4cc printk
modifier to print FourCC codes
> > date: 11 months ago
> > config: mips-buildonly-randconfig-r002-20220107
(https://download.01.org/0day-ci/archive/20220108/202201081852.uTfBqS4b-lk...)
> > compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
32167bfe64a4c5dd4eb3f7a58e24f4cba76f5ac2)
> > reproduce (this is a W=1 build):
> > wget
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
> > chmod +x ~/bin/make.cross
> > # install mips cross compiling tool for clang build
> > # apt-get install binutils-mips-linux-gnu
> > #
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit...
> > git remote add linus
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> > git fetch --no-tags linus master
> > git checkout e927e1e0f0dd3e353d5556503a71484008692c82
> > # save the config file to linux build tree
> > mkdir build_dir
> > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1
O=build_dir ARCH=mips SHELL=/bin/bash drivers/hid/ drivers/media/v4l2-core/ fs/
> >
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp(a)intel.com>
> >
> > All warnings (new ones prefixed by >>):
> >
> > >> drivers/media/v4l2-core/v4l2-ioctl.c:303:28: warning: taking address
of packed member 'pixelformat' of class or structure
'v4l2_pix_format_mplane' may result in an unaligned pointer value
[-Waddress-of-packed-member]
> > mp->width, mp->height,
&mp->pixelformat,
> > ^~~~~~~~~~~~~~~
> > include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
> > printk(KERN_CONT fmt, ##__VA_ARGS__)
> > ^~~~~~~~~~~
> > >> drivers/media/v4l2-core/v4l2-ioctl.c:347:37: warning: taking address
of packed member 'pixelformat' of class or structure 'v4l2_sdr_format' may
result in an unaligned pointer value [-Waddress-of-packed-member]
> > pr_cont(", pixelformat=%p4cc\n",
&sdr->pixelformat);
> > ^~~~~~~~~~~~~~~~
> > include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
> > printk(KERN_CONT fmt, ##__VA_ARGS__)
> > ^~~~~~~~~~~
> > >> drivers/media/v4l2-core/v4l2-ioctl.c:353:5: warning: taking address of
packed member 'dataformat' of class or structure 'v4l2_meta_format' may
result in an unaligned pointer value [-Waddress-of-packed-member]
> > &meta->dataformat, meta->buffersize);
> > ^~~~~~~~~~~~~~~~
> > include/linux/printk.h:385:26: note: expanded from macro 'pr_cont'
> > printk(KERN_CONT fmt, ##__VA_ARGS__)
--
With Best Regards,
Andy Shevchenko
8:22 a.m.
On Mon, Jan 10, 2022 at 12:50 PM Andy Shevchenko
<andy.shevchenko(a)gmail.com> wrote:
On Mon, Jan 10, 2022 at 11:44:12AM -0800, Nick Desaulniers wrote:
> On Sun, Jan 9, 2022 at 6:26 AM Andy Shevchenko
> <andy.shevchenko(a)gmail.com> wrote:
> >
> > +Nick Desaulniers
> >
> > Any ideas on how to fix this?
>
> Not obviously.
Thanks for looking into this!
> This code probably will trigger a splat when run with
> UBSan though.
>
> I'm curious if the structure needs to be packed for interfacing with
> hardware or some ABI, or whether we could add an explicit alignment to
> the member if that would be ok (which may add back some padding)?
Looking into it I think removing packed attribute brings a regression
immediately on 64-bit platforms since u32 member followed by u8.
> Otherwise, I suspect to actually access this properly we may have
> macros for performing underaligned loads and stores? I suspect you'd
> read potentially unaligned data into an aligned copy, then do
> operations on that, at which point printing the address of the copy is
> legal, but perhaps useless.
Current code does this:
val = *fourcc & ~BIT(31);
...
for (i = 0; i < sizeof(*fourcc); i++) {
...
strcpy(p, *fourcc & BIT(31) ? " big-endian" : "
little-endian");
...
p = special_hex_number(p, output + sizeof(output) - 2, *fourcc, sizeof(u32));
If unaligned access is not good it will crash on some architectures AFAIU.
So, it should use get_unaligned() in the first place.
Regardless of your unaligned access patch
(https://lore.kernel.org/lkml/20220110205049.11696-1-andriy.shevchenko@lin...),
taking the address of a packed member will still have a warning:
https://godbolt.org/z/8r1rcocPY
So it looks like packing a struct sets the alignment of members to 1,
ie. under-aligning them. You need to restore the alignment of the
members you plan to take the address of.
ie.
struct w {
char x, y, z;
} __attribute__((packed));
is equivalent in layout and alignment to:
struct w {
char __attribute__((aligned(1))) x;
char __attribute__((aligned(1))) y;
char __attribute__((aligned(1))) z;
} __attribute__((aligned(1)));
For `struct v4l2_pix_format_mplane` we probably want the trailing
char's to have alignment 1, rather than every member. We can either be
explicit with __aligned(1) on them, or __aligned(4) on the uint
members and retain __packed.
> Perhaps:
>
> - __u32 pixelformat;
> + __u32 pixelformat __aligned(4);
This looks weird, however I can't immediately see any side effects of it.
What if the address of the entire structure is unaligned, would we have a
gap here? In any case I wouldn't go this way.
> __u32 field;
> __u32 colorspace;
>
> Perhaps we could tighten up this warning in clang; we don't have any
> holes before this member, so I _wouldn't_ have assumed
> __attribute__((packed)) would have caused the address of pixelformat
> member of an instance of struct v4l2_pix_format_mplane to ever be
> underaligned.
>
> > On Sun, Jan 9, 2022 at 3:53 PM kernel test robot <lkp(a)intel.com> wrote:
> > >
> > > Hi Sakari,
> > >
> > > FYI, the error/warning still remains.
> > >
> > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
master
> > > head: d1587f7bfe9a0f97a75d42ac1489aeda551106bc
> > > commit: e927e1e0f0dd3e353d5556503a71484008692c82 v4l: ioctl: Use %p4cc
printk modifier to print FourCC codes
> > > date: 11 months ago
> > > config: mips-buildonly-randconfig-r002-20220107
(https://download.01.org/0day-ci/archive/20220108/202201081852.uTfBqS4b-lk...)
> > > compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
32167bfe64a4c5dd4eb3f7a58e24f4cba76f5ac2)
> > > reproduce (this is a W=1 build):
> > > wget
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
> > > chmod +x ~/bin/make.cross
> > > # install mips cross compiling tool for clang build
> > > # apt-get install binutils-mips-linux-gnu
> > > #
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit...
> > > git remote add linus
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> > > git fetch --no-tags linus master
> > > git checkout e927e1e0f0dd3e353d5556503a71484008692c82
> > > # save the config file to linux build tree
> > > mkdir build_dir
> > > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1
O=build_dir ARCH=mips SHELL=/bin/bash drivers/hid/ drivers/media/v4l2-core/ fs/
> > >
> > > If you fix the issue, kindly add following tag as appropriate
> > > Reported-by: kernel test robot <lkp(a)intel.com>
> > >
> > > All warnings (new ones prefixed by >>):
> > >
> > > >> drivers/media/v4l2-core/v4l2-ioctl.c:303:28: warning: taking
address of packed member 'pixelformat' of class or structure
'v4l2_pix_format_mplane' may result in an unaligned pointer value
[-Waddress-of-packed-member]
> > > mp->width, mp->height,
&mp->pixelformat,
> > > ^~~~~~~~~~~~~~~
> > > include/linux/printk.h:385:26: note: expanded from macro
'pr_cont'
> > > printk(KERN_CONT fmt, ##__VA_ARGS__)
> > > ^~~~~~~~~~~
> > > >> drivers/media/v4l2-core/v4l2-ioctl.c:347:37: warning: taking
address of packed member 'pixelformat' of class or structure
'v4l2_sdr_format' may result in an unaligned pointer value
[-Waddress-of-packed-member]
> > > pr_cont(", pixelformat=%p4cc\n",
&sdr->pixelformat);
> > > ^~~~~~~~~~~~~~~~
> > > include/linux/printk.h:385:26: note: expanded from macro
'pr_cont'
> > > printk(KERN_CONT fmt, ##__VA_ARGS__)
> > > ^~~~~~~~~~~
> > > >> drivers/media/v4l2-core/v4l2-ioctl.c:353:5: warning: taking
address of packed member 'dataformat' of class or structure
'v4l2_meta_format' may result in an unaligned pointer value
[-Waddress-of-packed-member]
> > > &meta->dataformat,
meta->buffersize);
> > > ^~~~~~~~~~~~~~~~
> > > include/linux/printk.h:385:26: note: expanded from macro
'pr_cont'
> > > printk(KERN_CONT fmt, ##__VA_ARGS__)
--
With Best Regards,
Andy Shevchenko
--
Thanks,
~Nick Desaulniers
253
days inactive
255
days old
4 comments
3 participants
participants (3)
-
Andy Shevchenko -
kernel test robot -
Nick Desaulniers