Re: [PATCH 8/8] ALSA: emu10k1: add high-rate playback in E-MU D.A.S. mode

[kernel test robot <lkp@intel.com>]

Hi Oswald,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tiwai-sound/for-next]
[also build test WARNING on next-20230621]
[cannot apply to tiwai-sound/for-linus linus/master v6.4-rc7]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Oswald-Buddenhagen/ALSA-emu10k1-introduce-alternative-E-MU-D-A-S-mode/20230613-154242
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git for-next
patch link:    https://lore.kernel.org/r/20230613073822.1343234-9-oswald.buddenhagen%40gmx.de
patch subject: [PATCH 8/8] ALSA: emu10k1: add high-rate playback in E-MU D.A.S. mode
config: i386-randconfig-s002-20230621 (https://download.01.org/0day-ci/archive/20230622/202306221430.7QukSHhG-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce: (https://download.01.org/0day-ci/archive/20230622/202306221430.7QukSHhG-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202306221430.7QukSHhG-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> sound/pci/emu10k1/emupcm.c:1180:45: sparse: sparse: cast removes address space '__user' of expression
>> sound/pci/emu10k1/emupcm.c:1182:41: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected void const volatile [noderef] __user *ptr @@     got unsigned int [usertype] *src @@
   sound/pci/emu10k1/emupcm.c:1182:41: sparse:     expected void const volatile [noderef] __user *ptr
   sound/pci/emu10k1/emupcm.c:1182:41: sparse:     got unsigned int [usertype] *src

vim +/__user +1180 sound/pci/emu10k1/emupcm.c

  1146	
  1147	static int snd_emu10k1_efx_playback_copy_user(struct snd_pcm_substream *substream,
  1148						      int channel, unsigned long hwoff,
  1149						      void __user *buf, unsigned long bytes)
  1150	{
  1151		struct snd_emu10k1 *emu = snd_pcm_substream_chip(substream);
  1152		struct snd_pcm_runtime *runtime = substream->runtime;
  1153		unsigned shift = emu->emu1010.clock_shift;
  1154		unsigned i, j, k, channels, subchans, voices, frame_size, frames;
  1155	
  1156		if (!shift) {
  1157			// Non-interleaved source
  1158			if (copy_from_user(get_dma_ptr(runtime, channel, hwoff), buf, bytes))
  1159				return -EFAULT;
  1160		} else {
  1161			// Interleaved source
  1162			channels = runtime->channels;
  1163			subchans = 1 << shift;
  1164			voices = channels << shift;
  1165			frame_size = voices << 2;
  1166			// It is recommended that writes are period-sized, and it appears
  1167			// unlikely that someone would actually use a period size which
  1168			// is not divisible by four, so don't bother making it work.
  1169			// This check should also prevent that hwoff becomes unaligned.
  1170			// Ideally, snd_pcm_sw_params.xfer_align would handle this ...
  1171			if (bytes % frame_size)
  1172				return -EIO;
  1173			frames = bytes / frame_size;
  1174			hwoff /= voices;
  1175			if (!user_access_begin(buf, bytes))
  1176				return -EFAULT;
  1177			for (i = 0; i < channels; i++) {
  1178				for (j = 0; j < subchans; j++) {
  1179					u32 *dst = get_dma_ptr_x(runtime, shift, i, j, hwoff);
> 1180					u32 *src = (u32 *)buf + j * channels + i;
  1181					for (k = 0; k < frames; k++, dst++, src += voices)
> 1182						unsafe_get_user(*dst, src, faulted);
  1183				}
  1184			}
  1185			user_access_end();
  1186		}
  1187		return 0;
  1188	
  1189	faulted:
  1190		user_access_end();
  1191		return -EFAULT;
  1192	}
  1193	

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