llvmpipe: do constant buffer bounds checking in shaders

It's possible to bind a smaller buffer as a constant buffer, than
what the shader actually uses/requires. This could cause nasty
crashes. This patch adds the architecture to pass the maximum
allowable constant buffer index to the jit to let it make
sure that the constant buffer indices are always within bounds.
The behavior follows the d3d10 spec, which says the overflow
should always return all zeros, and overflow is only defined
as access beyond the size of the currently bound buffer. Accesses
beyond the declared shader constant register size are not
considered an overflow and expected to return garbage but consistent
garbage (we follow the behavior which some wlk tests expect which
is to return the actual values from the bound buffer).

Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>

1 files changed, 21 insertions, 11 deletions

diff --git a/src/gallium/auxiliary/draw/draw_llvm.h b/src/gallium/auxiliary/draw/draw_llvm.h
index 1d238a2a9c2..2e465b2239c 100644
--- a/src/gallium/auxiliary/draw/draw_llvm.h
+++ b/src/gallium/auxiliary/draw/draw_llvm.h
@@ -123,6 +123,7 @@ enum {
 struct draw_jit_context
 {
    const float *vs_constants[LP_MAX_TGSI_CONST_BUFFERS];
+   int num_vs_constants[LP_MAX_TGSI_CONST_BUFFERS];
    float (*planes) [DRAW_TOTAL_CLIP_PLANES][4];
    float *viewport;
 
@@ -131,17 +132,21 @@ struct draw_jit_context
 };
 
 enum {
-   DRAW_JIT_CTX_CONSTANTS   = 0,
-   DRAW_JIT_CTX_PLANES      = 1,
-   DRAW_JIT_CTX_VIEWPORT    = 2,
-   DRAW_JIT_CTX_TEXTURES    = 3,
-   DRAW_JIT_CTX_SAMPLERS    = 4,
+   DRAW_JIT_CTX_CONSTANTS            = 0,
+   DRAW_JIT_CTX_NUM_CONSTANTS        = 1,
+   DRAW_JIT_CTX_PLANES               = 2,
+   DRAW_JIT_CTX_VIEWPORT             = 3,
+   DRAW_JIT_CTX_TEXTURES             = 4,
+   DRAW_JIT_CTX_SAMPLERS             = 5,
    DRAW_JIT_CTX_NUM_FIELDS
 };
 
 #define draw_jit_context_vs_constants(_gallivm, _ptr) \
    lp_build_struct_get_ptr(_gallivm, _ptr, DRAW_JIT_CTX_CONSTANTS, "vs_constants")
 
+#define draw_jit_context_num_vs_constants(_gallivm, _ptr) \
+   lp_build_struct_get_ptr(_gallivm, _ptr, DRAW_JIT_CTX_NUM_CONSTANTS, "num_vs_constants")
+
 #define draw_jit_context_planes(_gallivm, _ptr) \
    lp_build_struct_get(_gallivm, _ptr, DRAW_JIT_CTX_PLANES, "planes")
 
@@ -200,6 +205,7 @@ enum {
 struct draw_gs_jit_context
 {
    const float *constants[LP_MAX_TGSI_CONST_BUFFERS];
+   int num_constants[LP_MAX_TGSI_CONST_BUFFERS];
    float (*planes) [DRAW_TOTAL_CLIP_PLANES][4];
    float *viewport;
 
@@ -215,23 +221,27 @@ struct draw_gs_jit_context
 
 enum {
    DRAW_GS_JIT_CTX_CONSTANTS = 0,
-   DRAW_GS_JIT_CTX_PLANES = 1,
-   DRAW_GS_JIT_CTX_VIEWPORT = 2,
+   DRAW_GS_JIT_CTX_NUM_CONSTANTS = 1,
+   DRAW_GS_JIT_CTX_PLANES = 2,
+   DRAW_GS_JIT_CTX_VIEWPORT = 3,
    /* Textures and samples are reserved for DRAW_JIT_CTX_TEXTURES
     * and DRAW_JIT_CTX_SAMPLERS, because they both need
     * to be at exactly the same locations as they are in the
     * VS ctx structure for sampling to work. */
    DRAW_GS_JIT_CTX_TEXTURES = DRAW_JIT_CTX_TEXTURES,
    DRAW_GS_JIT_CTX_SAMPLERS = DRAW_JIT_CTX_SAMPLERS,
-   DRAW_GS_JIT_CTX_PRIM_LENGTHS = 5,
-   DRAW_GS_JIT_CTX_EMITTED_VERTICES = 6,
-   DRAW_GS_JIT_CTX_EMITTED_PRIMS = 7,
-   DRAW_GS_JIT_CTX_NUM_FIELDS = 8
+   DRAW_GS_JIT_CTX_PRIM_LENGTHS = 6,
+   DRAW_GS_JIT_CTX_EMITTED_VERTICES = 7,
+   DRAW_GS_JIT_CTX_EMITTED_PRIMS = 8,
+   DRAW_GS_JIT_CTX_NUM_FIELDS = 9
 };
 
 #define draw_gs_jit_context_constants(_gallivm, _ptr) \
    lp_build_struct_get_ptr(_gallivm, _ptr, DRAW_GS_JIT_CTX_CONSTANTS, "constants")
 
+#define draw_gs_jit_context_num_constants(_gallivm, _ptr) \
+   lp_build_struct_get_ptr(_gallivm, _ptr, DRAW_GS_JIT_CTX_NUM_CONSTANTS, "num_constants")
+
 #define draw_gs_jit_context_planes(_gallivm, _ptr) \
    lp_build_struct_get(_gallivm, _ptr, DRAW_GS_JIT_CTX_PLANES, "planes")