[Mesa-dev] [PATCH 2/3] intel/gen_decoder: return -1 for unknown command formats

[Jordan Justen]

Decoding with aubinator encountered a command of 0xffffffff. With the
previous code, it caused aubinator to jump 255 + 2 dwords to start
decoding again.

Instead we can attempt to detect the known instruction formats. If the
format is not recognized, then we can advance just 1 dword.

Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
---
 src/intel/common/gen_decoder.c                | 21 +++++++++++++++------
 src/intel/tools/aubinator.c                   |  4 ++--
 src/mesa/drivers/dri/i965/intel_batchbuffer.c |  2 ++
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/intel/common/gen_decoder.c b/src/intel/common/gen_decoder.c
index 1244f4c4480..d5ba3e6265e 100644
--- a/src/intel/common/gen_decoder.c
+++ b/src/intel/common/gen_decoder.c
@@ -692,28 +692,37 @@ gen_group_get_length(struct gen_group *group, const uint32_t *p)
 
    case 3: /* Render */ {
       uint32_t subtype = field(h, 27, 28);
+      uint32_t opcode = field(h, 24, 26);
       switch (subtype) {
       case 0:
-         return field(h, 0, 7) + 2;
+         if (opcode < 2)
+            return field(h, 0, 7) + 2;
+         else
+            return -1;
       case 1:
-         return 1;
+         if (opcode < 2)
+            return 1;
+         else
+            return -1;
       case 2: {
-         uint32_t opcode = field(h, 24, 26);
-         assert(opcode < 3 /* 3 and above currently reserved */);
          if (opcode == 0)
             return field(h, 0, 7) + 2;
          else if (opcode < 3)
             return field(h, 0, 15) + 2;
          else
-            return 1; /* FIXME: if more opcodes are added */
+            return -1;
       }
       case 3:
-         return field(h, 0, 7) + 2;
+         if (opcode < 4)
+            return field(h, 0, 7) + 2;
+         else
+            return -1;
       }
    }
    }
 
    unreachable("bad opcode");
+   return -1;
 }
 
 void
diff --git a/src/intel/tools/aubinator.c b/src/intel/tools/aubinator.c
index cae578babac..a64bce7a536 100644
--- a/src/intel/tools/aubinator.c
+++ b/src/intel/tools/aubinator.c
@@ -687,12 +687,12 @@ parse_commands(struct gen_spec *spec, uint32_t *cmds, int size, int engine)
 
    for (p = cmds; p < end; p += length) {
       inst = gen_spec_find_instruction(spec, p);
+      length = gen_group_get_length(inst, p);
       if (inst == NULL) {
          fprintf(outfile, "unknown instruction %08x\n", p[0]);
-         length = (p[0] & 0xff) + 2;
+         length = MIN2(1, length);
          continue;
       }
-      length = gen_group_get_length(inst, p);
 
       const char *color, *reset_color = NORMAL;
       uint64_t offset;
diff --git a/src/mesa/drivers/dri/i965/intel_batchbuffer.c b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
index 54bab9efb02..d16b4622456 100644
--- a/src/mesa/drivers/dri/i965/intel_batchbuffer.c
+++ b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
@@ -318,6 +318,8 @@ do_batch_dump(struct brw_context *brw)
       }
 
       length = gen_group_get_length(inst, p);
+      assert(length > 0);
+      length = MAX2(length, 1);
    }
 
    if (ret == 0) {
-- 
2.11.0