[Mesa-dev] [PATCH 08/33] intel: decoder: don't read qword outside instruction/struct limit

[Lionel Landwerlin]

We used to print invalid data when the last field was being clamped to
32bits due to Dword Length of the whole instruction. Here is an
example where the decoder read part of the next instruction instead of
stopping at the 32bit limit:

0x000ce0b4:  0x10000002:  MI_STORE_DATA_IMM
0x000ce0b4:  0x10000002 : Dword 0
    DWord Length: 2
    Store Qword: 0
    Use Global GTT: false
0x000ce0b8:  0x00045010 : Dword 1
    Core Mode Enable: 0
    Address: 0x00045010
0x000ce0bc:  0x00000000 : Dword 2
0x000ce0c0:  0x00000000 : Dword 3
    Immediate Data: 8791026489807077376

With this change we have the proper value :

0x000ce0b4:  0x10000002:  MI_STORE_DATA_IMM (4 Dwords)
0x000ce0b4:  0x10000002 : Dword 0
    DWord Length: 2
    Store Qword: 0
    Use Global GTT: false
0x000ce0b8:  0x00045010 : Dword 1
    Core Mode Enable: 0
    Address: 0x00045010
0x000ce0bc:  0x00000000 : Dword 2
0x000ce0c0:  0x00000000 : Dword 3
    Immediate Data: 0

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
---
 src/intel/common/gen_decoder.c | 11 ++++++++---
 src/intel/common/gen_decoder.h |  1 +
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/intel/common/gen_decoder.c b/src/intel/common/gen_decoder.c
index 4ce3a577f96..c1affc47a02 100644
--- a/src/intel/common/gen_decoder.c
+++ b/src/intel/common/gen_decoder.c
@@ -842,9 +842,13 @@ gen_field_decode(struct gen_field_iterator *iter)
    else
       memset(iter->name, 0, sizeof(iter->name));
 
-   if ((iter->field->end - iter->field->start) > 32)
-      v.qw = ((uint64_t) iter->p[iter->dword+1] << 32) | iter->p[iter->dword];
-   else
+   memset(&v, 0, sizeof(v));
+
+   if ((iter->field->end - iter->field->start) > 32) {
+      if (&iter->p[iter->dword + 1] < iter->end)
+         v.qw = ((uint64_t) iter->p[iter->dword+1] << 32);
+      v.qw |= iter->p[iter->dword];
+   } else
       v.qw = iter->p[iter->dword];
 
    const char *enum_name = NULL;
@@ -933,6 +937,7 @@ gen_field_iterator_init(struct gen_field_iterator *iter,
    else
       iter->field = group->next->fields;
    iter->p = p;
+   iter->end = &p[gen_group_get_length(iter->group, iter->p)];
    iter->print_colors = print_colors;
 
    gen_field_decode(iter);
diff --git a/src/intel/common/gen_decoder.h b/src/intel/common/gen_decoder.h
index b11927d2693..4d9edf78ff0 100644
--- a/src/intel/common/gen_decoder.h
+++ b/src/intel/common/gen_decoder.h
@@ -57,6 +57,7 @@ struct gen_field_iterator {
    char value[128];
    struct gen_group *struct_desc;
    const uint32_t *p;
+   const uint32_t *end;
    int dword; /**< current field starts at &p[dword] */
 
    int group_iter;
-- 
2.15.0.rc2