[Mesa-dev] [PATCH] aubinator: Fix the decoding of values that span two Dwords

[Sirisha Gandikota]

From: Sirisha Gandikota <Sirisha.Gandikota at intel.com>

Fixed the way the values that span two Dwords are decoded.
Based on the start and end indices of the field, the Dwords
are fetched and decoded accordingly.

Earlier, 64-bit fields (such as most pointers on Gen8+)
weren't decoded correctly.  gen_field_iterator_next seemed
to walk one DWord at a time, sets v.dw, and then passes it
to field(). So, even though field() takes a uint64_t, we're
passing it a uint32_t (which gets promoted, so the top 32
bits will always be zero). This seems pretty bogus... (Ken)

Signed-off-by: Sirisha Gandikota <Sirisha.Gandikota at intel.com>
---
 src/intel/tools/decoder.c | 40 ++++++++++++++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 8 deletions(-)

diff --git a/src/intel/tools/decoder.c b/src/intel/tools/decoder.c
index b5f557c..bea9f22 100644
--- a/src/intel/tools/decoder.c
+++ b/src/intel/tools/decoder.c
@@ -191,6 +191,26 @@ get_register_offset(const char **atts, uint32_t *offset)
    return;
 }
 
+static void
+get_start_end_pos(int *start, int *end)
+{
+   /* start value has to be mod with 32 as we need the relative
+    * start position in the first DWord. For the end position, add
+    * the length of the field to the start position to get the
+    * relative postion in the 64 bit address.
+    */
+   if (*end - *start > 32) {
+      int len = *end - *start;
+      *start = *start % 32;
+      *end = *start + len;
+   } else {
+      *start = *start % 32;
+      *end = *end % 32;
+   }
+
+   return;
+}
+
 static inline uint64_t
 mask(int start, int end)
 {
@@ -204,18 +224,16 @@ mask(int start, int end)
 static inline uint64_t
 field(uint64_t value, int start, int end)
 {
-   /* The field values are obtained from the DWord,
-    * Hence, get the relative start and end positions
-    * by doing a %32 on the start and end positions
-    */
-   return (value & mask(start % 32, end % 32)) >> (start % 32);
+   get_start_end_pos(&start, &end);
+   return (value & mask(start, end)) >> (start);
 }
 
 static inline uint64_t
 field_address(uint64_t value, int start, int end)
 {
    /* no need to right shift for address/offset */
-   return (value & mask(start % 32, end % 32));
+   get_start_end_pos(&start, &end);
+   return (value & mask(start, end));
 }
 
 static struct gen_type
@@ -491,7 +509,7 @@ gen_field_iterator_next(struct gen_field_iterator *iter)
 {
    struct gen_field *f;
    union {
-      uint32_t dw;
+      uint64_t dw;
       float f;
    } v;
 
@@ -500,7 +518,13 @@ gen_field_iterator_next(struct gen_field_iterator *iter)
 
    f = iter->group->fields[iter->i++];
    iter->name = f->name;
-   v.dw = iter->p[f->start / 32];
+   int index = f->start / 32;
+
+   if ((f->end - f->start) > 32)
+      v.dw = ((uint64_t) iter->p[index+1] << 32 ) | iter->p[index];
+   else
+      v.dw = iter->p[index];
+
    switch (f->type.kind) {
    case GEN_TYPE_UNKNOWN:
    case GEN_TYPE_INT:
-- 
2.7.4