Re: [PATCH 5/6] drm/radeon: add VRAM debugfs access

[Alex Deucher <alexdeucher@gmail.com>]

On Thu, Dec 12, 2013 at 3:42 AM, Christian König
<deathsimple@vodafone.de> wrote:
> From: Christian König <christian.koenig@amd.com>
>
> Not very fast, but makes it possible to access even the
> normally inaccessible parts of VRAM from userspace.
>
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/gpu/drm/radeon/radeon.h     |  4 +++
>  drivers/gpu/drm/radeon/radeon_ttm.c | 72 ++++++++++++++++++++++++++++++++++++-
>  2 files changed, 75 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
> index b1f990d..49f210c1 100644
> --- a/drivers/gpu/drm/radeon/radeon.h
> +++ b/drivers/gpu/drm/radeon/radeon.h
> @@ -413,6 +413,10 @@ struct radeon_mman {
>         struct ttm_bo_device            bdev;
>         bool                            mem_global_referenced;
>         bool                            initialized;
> +
> +#if defined(CONFIG_DEBUG_FS)
> +       struct dentry                   *vram;
> +#endif
>  };
>
>  /* bo virtual address in a specific vm */
> diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
> index a2d6c4f..f5e8eed 100644
> --- a/drivers/gpu/drm/radeon/radeon_ttm.c
> +++ b/drivers/gpu/drm/radeon/radeon_ttm.c
> @@ -39,12 +39,14 @@
>  #include <linux/seq_file.h>
>  #include <linux/slab.h>
>  #include <linux/swiotlb.h>
> +#include <linux/debugfs.h>
>  #include "radeon_reg.h"
>  #include "radeon.h"
>
>  #define DRM_FILE_PAGE_OFFSET (0x100000000ULL >> PAGE_SHIFT)
>
>  static int radeon_ttm_debugfs_init(struct radeon_device *rdev);
> +static void radeon_ttm_debugfs_fini(struct radeon_device *rdev);
>
>  static struct radeon_device *radeon_get_rdev(struct ttm_bo_device *bdev)
>  {
> @@ -753,6 +755,7 @@ void radeon_ttm_fini(struct radeon_device *rdev)
>
>         if (!rdev->mman.initialized)
>                 return;
> +       radeon_ttm_debugfs_fini(rdev);
>         if (rdev->stollen_vga_memory) {
>                 r = radeon_bo_reserve(rdev->stollen_vga_memory, false);
>                 if (r == 0) {
> @@ -862,12 +865,70 @@ static struct drm_info_list radeon_ttm_debugfs_list[] = {
>  #endif
>  };
>
> +static int radeon_ttm_mem_open(struct inode *inode, struct file *filep)
> +{
> +       filep->private_data = inode->i_private;
> +       return 0;
> +}
> +
> +static ssize_t radeon_ttm_vram_read(struct file *f, char __user *buf,
> +                                   size_t size, loff_t *pos)
> +{
> +       struct radeon_device *rdev = f->private_data;
> +       ssize_t result = 0;
> +       int r;
> +
> +       if (size & 0x3 || *pos & 0x3)
> +               return -EINVAL;
> +
> +       while (size) {
> +               unsigned long flags;
> +               uint32_t value;
> +
> +               if (*pos >= rdev->mc.mc_vram_size || *pos >= 0x7FFFFFFF)
> +                       return result;
> +
> +               spin_lock_irqsave(&rdev->mmio_idx_lock, flags);
> +               WREG32(RADEON_MM_INDEX, ((uint32_t)*pos) | 0x80000000);

Starting with evergreen dGPUs, there is also an MM_INDEX_HI register
at 0x18 for accessing addresses over 30 bits.

Alex


> +               value = RREG32(RADEON_MM_DATA);
> +               spin_unlock_irqrestore(&rdev->mmio_idx_lock, flags);
> +
> +               r = put_user(value, (uint32_t *)buf);
> +               if (r)
> +                       return r;
> +
> +               result += 4;
> +               buf += 4;
> +               *pos += 4;
> +               size -= 4;
> +       }
> +
> +       return result;
> +}
> +
> +static const struct file_operations radeon_ttm_vram_fops = {
> +       .owner = THIS_MODULE,
> +       .open = radeon_ttm_mem_open,
> +       .read = radeon_ttm_vram_read,
> +};
> +
>  #endif
>
>  static int radeon_ttm_debugfs_init(struct radeon_device *rdev)
>  {
>  #if defined(CONFIG_DEBUG_FS)
> -       unsigned count = ARRAY_SIZE(radeon_ttm_debugfs_list);
> +       unsigned count;
> +
> +       struct drm_minor *minor = rdev->ddev->primary;
> +       struct dentry *ent, *root = minor->debugfs_root;
> +
> +       ent = debugfs_create_file("radeon_vram", S_IFREG | S_IRUGO, root,
> +                                 rdev, &radeon_ttm_vram_fops);
> +       if (IS_ERR(ent))
> +               return PTR_ERR(ent);
> +       rdev->mman.vram = ent;
> +
> +       count = ARRAY_SIZE(radeon_ttm_debugfs_list);
>
>  #ifdef CONFIG_SWIOTLB
>         if (!swiotlb_nr_tbl())
> @@ -880,3 +941,12 @@ static int radeon_ttm_debugfs_init(struct radeon_device *rdev)
>         return 0;
>  #endif
>  }
> +
> +static void radeon_ttm_debugfs_fini(struct radeon_device *rdev)
> +{
> +#if defined(CONFIG_DEBUG_FS)
> +
> +       debugfs_remove(rdev->mman.vram);
> +       rdev->mman.vram = NULL;
> +#endif
> +}
> --
> 1.8.1.2
>
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