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drm/i915/bios: abstract finding the panel sequence block

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Make the whole thing easier to read. While at it, make the parsing more
robust, and ensure we don't read past buffer being parsed.

v2: improve commit message (Daniel)

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1452001851-8967-1-git-send-email-jani.nikula@intel.com
This commit is contained in:
Jani Nikula 2016-01-05 15:50:51 +02:00
parent 08c0888b28
commit 5db72099e8
1 changed files with 42 additions and 34 deletions
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76
drivers/gpu/drm/i915/intel_bios.c
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@ -697,7 +697,7 @@ parse_psr(struct drm_i915_private *dev_priv, const struct bdb_header *bdb)
dev_priv->vbt.psr.tp2_tp3_wakeup_time = psr_table->tp2_tp3_wakeup_time;
}
static u8 *goto_next_sequence(u8 *data, int *size)
static u8 *goto_next_sequence(u8 *data, u16 *size)
{
u16 len;
int tmp = *size;
@ -818,15 +818,52 @@ parse_mipi_config(struct drm_i915_private *dev_priv,
dev_priv->vbt.dsi.panel_id = MIPI_DSI_GENERIC_PANEL_ID;
}
/* Find the sequence block and size for the given panel. */
static const u8 *
find_panel_sequence_block(const struct bdb_mipi_sequence *sequence,
u16 panel_id, u16 *seq_size)
{
u32 total = get_blocksize(sequence);
const u8 *data = &sequence->data[0];
u8 current_id;
u16 current_size;
int index = 0;
int i;
for (i = 0; i < MAX_MIPI_CONFIGURATIONS && index + 3 < total; i++) {
current_id = *(data + index);
index++;
current_size = *((const u16 *)(data + index));
index += 2;
if (index + current_size > total) {
DRM_ERROR("Invalid sequence block\n");
return NULL;
}
if (current_id == panel_id) {
*seq_size = current_size;
return data + index;
}
index += current_size;
}
DRM_ERROR("Sequence block detected but no valid configuration\n");
return NULL;
}
static void
parse_mipi_sequence(struct drm_i915_private *dev_priv,
const struct bdb_header *bdb)
{
const struct bdb_mipi_sequence *sequence;
const u8 *seq_data;
u16 seq_size;
u8 *data;
u16 block_size;
int i, panel_id, seq_size;
/* Only our generic panel driver uses the sequence block. */
if (dev_priv->vbt.dsi.panel_id != MIPI_DSI_GENERIC_PANEL_ID)
@ -853,40 +890,11 @@ parse_mipi_sequence(struct drm_i915_private *dev_priv,
*/
dev_priv->vbt.dsi.seq_version = sequence->version;
seq_data = &sequence->data[0];
/*
* sequence block is variable length and hence we need to parse and
* get the sequence data for specific panel id
*/
for (i = 0; i < MAX_MIPI_CONFIGURATIONS; i++) {
panel_id = *seq_data;
seq_size = *((u16 *) (seq_data + 1));
if (panel_id == panel_type)
break;
/* skip the sequence including seq header of 3 bytes */
seq_data = seq_data + 3 + seq_size;
if ((seq_data - &sequence->data[0]) > block_size) {
DRM_ERROR("Sequence start is beyond sequence block size, corrupted sequence block\n");
return;
}
}
if (i == MAX_MIPI_CONFIGURATIONS) {
DRM_ERROR("Sequence block detected but no valid configuration\n");
seq_data = find_panel_sequence_block(sequence, panel_type, &seq_size);
if (!seq_data)
return;
}
/* check if found sequence is completely within the sequence block
* just being paranoid */
if (seq_size > block_size) {
DRM_ERROR("Corrupted sequence/size, bailing out\n");
return;
}
/* skip the panel id(1 byte) and seq size(2 bytes) */
dev_priv->vbt.dsi.data = kmemdup(seq_data + 3, seq_size, GFP_KERNEL);
dev_priv->vbt.dsi.data = kmemdup(seq_data, seq_size, GFP_KERNEL);
if (!dev_priv->vbt.dsi.data)
return;