drm/i915: refactor VBT validation

Make the validation function a boolean operating on a buffer of given
size, removing the extra pointer dances.

Move the OpRegion based VBT validation to intel_opregion_setup(), only
initializing opregion->vbt if it's valid.

v2: move logging about valid VBT to opregion setup too (Ville)

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450178175-27420-1-git-send-email-jani.nikula@intel.com

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a2bd4c6a86a1843b8b4009e8ce524c17ccebf570..ef15f1710b503cdeaafedaba1ce5f3a53a384f0b 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3354,6 +3354,7 @@ extern void intel_i2c_reset(struct drm_device *dev);
 
 /* intel_bios.c */
 int intel_bios_init(struct drm_device *dev);
+bool intel_bios_is_valid_vbt(const void *buf, size_t size);
 
 /* intel_opregion.c */
 #ifdef CONFIG_ACPI

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 04fb9ded1805638c4c1ecb955f77b7878322657d..dc3a0fb1946ca8e152fef949fefe02b7341207d3 100644 (file)
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -1221,37 +1221,40 @@ static const struct bdb_header *get_bdb_header(const struct vbt_header *vbt)
        return _vbt + vbt->bdb_offset;
 }
 
-static const struct vbt_header *validate_vbt(const void *base,
-                                            size_t size,
-                                            const void *_vbt)
+/**
+ * intel_bios_is_valid_vbt - does the given buffer contain a valid VBT
+ * @buf:       pointer to a buffer to validate
+ * @size:      size of the buffer
+ *
+ * Returns true on valid VBT.
+ */
+bool intel_bios_is_valid_vbt(const void *buf, size_t size)
 {
-       size_t offset = _vbt - base;
-       const struct vbt_header *vbt = _vbt;
+       const struct vbt_header *vbt = buf;
        const struct bdb_header *bdb;
 
        if (!vbt)
-               return NULL;
+               return false;
 
-       if (offset + sizeof(struct vbt_header) > size) {
+       if (sizeof(struct vbt_header) > size) {
                DRM_DEBUG_DRIVER("VBT header incomplete\n");
-               return NULL;
+               return false;
        }
 
        if (memcmp(vbt->signature, "$VBT", 4)) {
                DRM_DEBUG_DRIVER("VBT invalid signature\n");
-               return NULL;
+               return false;
        }
 
-       offset += vbt->bdb_offset;
-       if (offset + sizeof(struct bdb_header) > size) {
+       if (vbt->bdb_offset + sizeof(struct bdb_header) > size) {
                DRM_DEBUG_DRIVER("BDB header incomplete\n");
-               return NULL;
+               return false;
        }
 
        bdb = get_bdb_header(vbt);
-       if (offset + bdb->bdb_size > size) {
+       if (vbt->bdb_offset + bdb->bdb_size > size) {
                DRM_DEBUG_DRIVER("BDB incomplete\n");
-               return NULL;
+               return false;
        }
 
        return vbt;
@@ -1259,26 +1262,27 @@ static const struct vbt_header *validate_vbt(const void *base,
 
 static const struct vbt_header *find_vbt(void __iomem *bios, size_t size)
 {
-       const struct vbt_header *vbt = NULL;
        size_t i;
 
        /* Scour memory looking for the VBT signature. */
        for (i = 0; i + 4 < size; i++) {
-               if (ioread32(bios + i) == *((const u32 *) "$VBT")) {
-                       /*
-                        * This is the one place where we explicitly discard the
-                        * address space (__iomem) of the BIOS/VBT. From now on
-                        * everything is based on 'base', and treated as regular
-                        * memory.
-                        */
-                       void *_bios = (void __force *) bios;
+               void *vbt;
 
-                       vbt = validate_vbt(_bios, size, _bios + i);
-                       break;
-               }
+               if (ioread32(bios + i) != *((const u32 *) "$VBT"))
+                       continue;
+
+               /*
+                * This is the one place where we explicitly discard the address
+                * space (__iomem) of the BIOS/VBT.
+                */
+               vbt = (void __force *) bios + i;
+               if (intel_bios_is_valid_vbt(vbt, size - i))
+                       return vbt;
+
+               break;
        }
 
-       return vbt;
+       return NULL;
 }
 
 /**
@@ -1295,7 +1299,7 @@ intel_bios_init(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct pci_dev *pdev = dev->pdev;
-       const struct vbt_header *vbt;
+       const struct vbt_header *vbt = dev_priv->opregion.vbt;
        const struct bdb_header *bdb;
        u8 __iomem *bios = NULL;
 
@@ -1304,12 +1308,7 @@ intel_bios_init(struct drm_device *dev)
 
        init_vbt_defaults(dev_priv);
 
-       /* XXX Should this validation be moved to intel_opregion.c? */
-       vbt = validate_vbt(dev_priv->opregion.header, OPREGION_SIZE,
-                          dev_priv->opregion.vbt);
-       if (vbt) {
-               DRM_DEBUG_KMS("Found valid VBT in ACPI OpRegion\n");
-       } else {
+       if (!vbt) {
                size_t size;
 
                bios = pci_map_rom(pdev, &size);

diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
index 5b9fc790d30089733fa40483db6a9a5ad1b8b2d6..859c9acbee730a26bdfd910f7198a0cfcb9a70e4 100644 (file)
--- a/drivers/gpu/drm/i915/intel_opregion.c
+++ b/drivers/gpu/drm/i915/intel_opregion.c
@@ -986,8 +986,15 @@ int intel_opregion_setup(struct drm_device *dev)
        if (mboxes & MBOX_ASLE_EXT)
                DRM_DEBUG_DRIVER("ASLE extension supported\n");
 
-       if (!dmi_check_system(intel_no_opregion_vbt))
-               opregion->vbt = base + OPREGION_VBT_OFFSET;
+       if (!dmi_check_system(intel_no_opregion_vbt)) {
+               void *vbt = base + OPREGION_VBT_OFFSET;
+               u32 vbt_size = OPREGION_SIZE - OPREGION_VBT_OFFSET;
+
+               if (intel_bios_is_valid_vbt(vbt, vbt_size)) {
+                       DRM_DEBUG_KMS("Found valid VBT in ACPI OpRegion\n");
+                       opregion->vbt = vbt;
+               }
+       }
 
        return 0;