Re: [drm-misc:for-linux-next 2/2] drivers/gpu/drm/drm_debugfs.c:212:33: sparse: sparse: non size-preserving pointer to integer cast

[Boris Brezillon <boris.brezillon@collabora.com>]

On Wed, 26 Jul 2023 00:25:36 +0200
Danilo Krummrich <dakr@redhat.com> wrote:

> On 7/24/23 09:27, Boris Brezillon wrote:
> > On Fri, 21 Jul 2023 02:06:16 +0800
> > kernel test robot <lkp@intel.com> wrote:
> >   
> >> tree:   git://anongit.freedesktop.org/drm/drm-misc for-linux-next
> >> head:   c7a472297169156252a50d76965eb36b081186e2
> >> commit: 4f66feeab173bd73e71028b8c2e1dcea07e32dd5 [2/2] drm: debugfs: provide infrastructure to dump a DRM GPU VA space
> >> config: i386-randconfig-r092-20230720 (https://download.01.org/0day-ci/archive/20230721/202307210230.t2OnM5g0-lkp@intel.com/config)
> >> compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
> >> reproduce: (https://download.01.org/0day-ci/archive/20230721/202307210230.t2OnM5g0-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/202307210230.t2OnM5g0-lkp@intel.com/
> >>
> >> sparse warnings: (new ones prefixed by >>)  
> >>>> drivers/gpu/drm/drm_debugfs.c:212:33: sparse: sparse: non size-preserving pointer to integer cast  
> >>
> >> vim +212 drivers/gpu/drm/drm_debugfs.c
> >>
> >>     178	
> >>     179	/**
> >>     180	 * drm_debugfs_gpuva_info - dump the given DRM GPU VA space
> >>     181	 * @m: pointer to the &seq_file to write
> >>     182	 * @mgr: the &drm_gpuva_manager representing the GPU VA space
> >>     183	 *
> >>     184	 * Dumps the GPU VA mappings of a given DRM GPU VA manager.
> >>     185	 *
> >>     186	 * For each DRM GPU VA space drivers should call this function from their
> >>     187	 * &drm_info_list's show callback.
> >>     188	 *
> >>     189	 * Returns: 0 on success, -ENODEV if the &mgr is not initialized
> >>     190	 */
> >>     191	int drm_debugfs_gpuva_info(struct seq_file *m,
> >>     192				   struct drm_gpuva_manager *mgr)
> >>     193	{
> >>     194		struct drm_gpuva *va, *kva = &mgr->kernel_alloc_node;
> >>     195	
> >>     196		if (!mgr->name)
> >>     197			return -ENODEV;
> >>     198	
> >>     199		seq_printf(m, "DRM GPU VA space (%s) [0x%016llx;0x%016llx]\n",
> >>     200			   mgr->name, mgr->mm_start, mgr->mm_start + mgr->mm_range);
> >>     201		seq_printf(m, "Kernel reserved node [0x%016llx;0x%016llx]\n",
> >>     202			   kva->va.addr, kva->va.addr + kva->va.range);
> >>     203		seq_puts(m, "\n");
> >>     204		seq_puts(m, " VAs | start              | range              | end                | object             | object offset\n");
> >>     205		seq_puts(m, "-------------------------------------------------------------------------------------------------------------\n");
> >>     206		drm_gpuva_for_each_va(va, mgr) {
> >>     207			if (unlikely(va == kva))
> >>     208				continue;
> >>     209	
> >>     210			seq_printf(m, "     | 0x%016llx | 0x%016llx | 0x%016llx | 0x%016llx | 0x%016llx\n",
> >>     211				   va->va.addr, va->va.range, va->va.addr + va->va.range,  
> >>   > 212				   (u64)va->gem.obj, va->gem.offset);  
> > 
> > Oops, I didn't notice it when reviewing. You're leaking a kernel address
> > to user space here. You should probably use %p to print the GEM object
> > address, and add `no_hash_pointers` to your cmdline when you want to
> > debug things.  
> 
> %p doesn't really work well in terms of formatting, plus for debugfs I 
> thought this might be fine. I could maybe use ptr_to_hashval(), but then 
> 'no_hash_pointers' wouldn't do anything for it.

Right, it's probably fine for debugfs indeed. Guess the uintptr_t cast
Steve suggested is the right fix then.