Re: [PATCH 16/22] gpu: host1x: Forbid unrelated SETCLASS opcode in the firewall

On 01.06.2017 20:46, Mikko Perttunen wrote:

With the simplification below and the is_addr_reg change mentioned,

Reviewed-by: Mikko Perttunen <redacted>

On 05/23/2017 03:14 AM, Dmitry Osipenko wrote:

quoted

Several channels could be made to write the same unit concurrently via the
SETCLASS opcode, trusting userspace is a bad idea. It should be possible to
drop the per-client channel reservation and add a per-unit locking by
inserting MLOCK's to the command stream to re-allow the SETCLASS opcode, but
it will be much more work. Let's forbid the unit-unrelated class changes for
now.

Signed-off-by: Dmitry Osipenko <redacted>
---
  drivers/gpu/drm/tegra/drm.c  |  1 +
  drivers/gpu/drm/tegra/drm.h  |  1 +
  drivers/gpu/drm/tegra/gr2d.c | 12 ++++++++++++
  drivers/gpu/host1x/job.c     | 24 ++++++++++++++++++++----
  include/linux/host1x.h       |  5 ++++-
  5 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index cdb05d6efde4..17416e1c219a 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c

@@ -531,6 +531,7 @@ int tegra_drm_submit(struct tegra_drm_context *context,
      }
        job->is_addr_reg = context->client->ops->is_addr_reg;
+    job->is_valid_class = context->client->ops->is_valid_class;
      job->syncpt_incrs = syncpt.incrs;
      job->syncpt_id = syncpt.id;
      job->timeout = 10000;

diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
index 85aa2e3d9d4e..6d6da01282f3 100644
--- a/drivers/gpu/drm/tegra/drm.h
+++ b/drivers/gpu/drm/tegra/drm.h

@@ -83,6 +83,7 @@ struct tegra_drm_client_ops {
                  struct tegra_drm_context *context);
      void (*close_channel)(struct tegra_drm_context *context);
      int (*is_addr_reg)(struct device *dev, u32 class, u32 offset);
+    int (*is_valid_class)(u32 class);
      int (*submit)(struct tegra_drm_context *context,
                struct drm_tegra_submit *args, struct drm_device *drm,
                struct drm_file *file);

diff --git a/drivers/gpu/drm/tegra/gr2d.c b/drivers/gpu/drm/tegra/gr2d.c
index 02cd3e37a6ec..782231c41a1a 100644
--- a/drivers/gpu/drm/tegra/gr2d.c
+++ b/drivers/gpu/drm/tegra/gr2d.c

@@ -109,10 +109,22 @@ static int gr2d_is_addr_reg(struct device *dev, u32

class, u32 offset)
      return 0;
  }
  +static int gr2d_is_valid_class(u32 class)
+{
+    switch (class) {
+    case HOST1X_CLASS_GR2D:
+    case HOST1X_CLASS_GR2D_SB:
+        return 1;
+    }
+
+    return 0;
+}

This could be just

return (class == HOST1X_CLASS_GR2D || class == HOST1X_CLASS_GR2D_SB);

That's a matter of a taste as both variants result in a same assembly being
generated. I don't mind your variant ;)

quoted

+
  static const struct tegra_drm_client_ops gr2d_ops = {
      .open_channel = gr2d_open_channel,
      .close_channel = gr2d_close_channel,
      .is_addr_reg = gr2d_is_addr_reg,
+    .is_valid_class = gr2d_is_valid_class,
      .submit = tegra_drm_submit,
  };
  diff --git a/drivers/gpu/host1x/job.c b/drivers/gpu/host1x/job.c
index cf335c5979e2..65e12219405a 100644

--- a/drivers/gpu/host1x/job.c
+++ b/drivers/gpu/host1x/job.c

@@ -358,6 +358,9 @@ struct host1x_firewall {
    static int check_register(struct host1x_firewall *fw, unsigned long offset)
  {
+    if (!fw->job->is_addr_reg)
+        return 0;
+
      if (fw->job->is_addr_reg(fw->dev, fw->class, offset)) {
          if (!fw->num_relocs)
              return -EINVAL;

@@ -372,6 +375,19 @@ static int check_register(struct host1x_firewall *fw,

unsigned long offset)
      return 0;
  }
  +static int check_class(struct host1x_firewall *fw, u32 class)
+{
+    if (!fw->job->is_valid_class) {
+        if (fw->class != class)
+            return -EINVAL;
+    } else {
+        if (!fw->job->is_valid_class(fw->class))
+            return -EINVAL;
+    }
+
+    return 0;
+}
+
  static int check_mask(struct host1x_firewall *fw)
  {
      u32 mask = fw->mask;

@@ -445,11 +461,9 @@ static int validate(struct host1x_firewall *fw, struct

host1x_job_gather *g)
  {
      u32 *cmdbuf_base = (u32 *)fw->job->gather_copy_mapped +
          (g->offset / sizeof(u32));
+    u32 job_class = fw->class;
      int err = 0;
  -    if (!fw->job->is_addr_reg)
-        return 0;
-
      fw->words = g->words;
      fw->cmdbuf = g->bo;
      fw->offset = 0;

@@ -469,7 +483,9 @@ static int validate(struct host1x_firewall *fw, struct

host1x_job_gather *g)
              fw->class = word >> 6 & 0x3ff;
              fw->mask = word & 0x3f;
              fw->reg = word >> 16 & 0xfff;
-            err = check_mask(fw);
+            err = check_class(fw, job_class);
+            if (!err)
+                err = check_mask(fw);
              if (err)
                  goto out;
              break;

diff --git a/include/linux/host1x.h b/include/linux/host1x.h
index aa323e43ae4e..561d6bb6580d 100644
--- a/include/linux/host1x.h
+++ b/include/linux/host1x.h

@@ -233,7 +233,10 @@ struct host1x_job {
      u8 *gather_copy_mapped;
        /* Check if register is marked as an address reg */
-    int (*is_addr_reg)(struct device *dev, u32 reg, u32 class);
+    int (*is_addr_reg)(struct device *dev, u32 class, u32 reg);
+
+    /* Check if class belongs to the unit */
+    int (*is_valid_class)(u32 class);
        /* Request a SETCLASS to this class */
      u32 class;

-- 
Dmitry