drivers/gpu/drm/vc4/vc4_validate_shaders.c

   1 /*
   2  * Copyright © 2014 Broadcom
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23
  24 /**
  25  * DOC: Shader validator for VC4.
  26  *
  27  * The VC4 has no IOMMU between it and system memory, so a user with
  28  * access to execute shaders could escalate privilege by overwriting
  29  * system memory (using the VPM write address register in the
  30  * general-purpose DMA mode) or reading system memory it shouldn't
  31  * (reading it as a texture, or uniform data, or vertex data).
  32  *
  33  * This walks over a shader BO, ensuring that its accesses are
  34  * appropriately bounded, and recording how many texture accesses are
  35  * made and where so that we can do relocations for them in the
  36  * uniform stream.
  37  */
  38
  39 #include "vc4_drv.h"
  40 #include "vc4_qpu_defines.h"
  41
  42 #define LIVE_REG_COUNT (32 + 32 + 4)
  43
  44 struct vc4_shader_validation_state {
  45         /* Current IP being validated. */
  46         uint32_t ip;
  47
  48         /* IP at the end of the BO, do not read shader[max_ip] */
  49         uint32_t max_ip;
  50
  51         uint64_t *shader;
  52
  53         struct vc4_texture_sample_info tmu_setup[2];
  54         int tmu_write_count[2];
  55
  56         /* For registers that were last written to by a MIN instruction with
  57          * one argument being a uniform, the address of the uniform.
  58          * Otherwise, ~0.
  59          *
  60          * This is used for the validation of direct address memory reads.
  61          */
  62         uint32_t live_min_clamp_offsets[LIVE_REG_COUNT];
  63         bool live_max_clamp_regs[LIVE_REG_COUNT];
  64         uint32_t live_immediates[LIVE_REG_COUNT];
  65
  66         /* Bitfield of which IPs are used as branch targets.
  67          *
  68          * Used for validation that the uniform stream is updated at the right
  69          * points and clearing the texturing/clamping state.
  70          */
  71         unsigned long *branch_targets;
  72
  73         /* Set when entering a basic block, and cleared when the uniform
  74          * address update is found.  This is used to make sure that we don't
  75          * read uniforms when the address is undefined.
  76          */
  77         bool needs_uniform_address_update;
  78
  79         /* Set when we find a backwards branch.  If the branch is backwards,
  80          * the taraget is probably doing an address reset to read uniforms,
  81          * and so we need to be sure that a uniforms address is present in the
  82          * stream, even if the shader didn't need to read uniforms in later
  83          * basic blocks.
  84          */
  85         bool needs_uniform_address_for_loop;
  86
  87         /* Set when we find an instruction writing the top half of the
  88          * register files.  If we allowed writing the unusable regs in
  89          * a threaded shader, then the other shader running on our
  90          * QPU's clamp validation would be invalid.
  91          */
  92         bool all_registers_used;
  93 };
  94
  95 static uint32_t
  96 waddr_to_live_reg_index(uint32_t waddr, bool is_b)
  97 {
  98         if (waddr < 32) {
  99                 if (is_b)
 100                         return 32 + waddr;
 101                 else
 102                         return waddr;
 103         } else if (waddr <= QPU_W_ACC3) {
 104                 return 64 + waddr - QPU_W_ACC0;
 105         } else {
 106                 return ~0;
 107         }
 108 }
 109
 110 static uint32_t
 111 raddr_add_a_to_live_reg_index(uint64_t inst)
 112 {
 113         uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
 114         uint32_t add_a = QPU_GET_FIELD(inst, QPU_ADD_A);
 115         uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
 116         uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
 117
 118         if (add_a == QPU_MUX_A)
 119                 return raddr_a;
 120         else if (add_a == QPU_MUX_B && sig != QPU_SIG_SMALL_IMM)
 121                 return 32 + raddr_b;
 122         else if (add_a <= QPU_MUX_R3)
 123                 return 64 + add_a;
 124         else
 125                 return ~0;
 126 }
 127
 128 static bool
 129 live_reg_is_upper_half(uint32_t lri)
 130 {
 131         return  (lri >= 16 && lri < 32) ||
 132                 (lri >= 32 + 16 && lri < 32 + 32);
 133 }
 134
 135 static bool
 136 is_tmu_submit(uint32_t waddr)
 137 {
 138         return (waddr == QPU_W_TMU0_S ||
 139                 waddr == QPU_W_TMU1_S);
 140 }
 141
 142 static bool
 143 is_tmu_write(uint32_t waddr)
 144 {
 145         return (waddr >= QPU_W_TMU0_S &&
 146                 waddr <= QPU_W_TMU1_B);
 147 }
 148
 149 static bool
 150 record_texture_sample(struct vc4_validated_shader_info *validated_shader,
 151                       struct vc4_shader_validation_state *validation_state,
 152                       int tmu)
 153 {
 154         uint32_t s = validated_shader->num_texture_samples;
 155         int i;
 156         struct vc4_texture_sample_info *temp_samples;
 157
 158         temp_samples = krealloc(validated_shader->texture_samples,
 159                                 (s + 1) * sizeof(*temp_samples),
 160                                 GFP_KERNEL);
 161         if (!temp_samples)
 162                 return false;
 163
 164         memcpy(&temp_samples[s],
 165                &validation_state->tmu_setup[tmu],
 166                sizeof(*temp_samples));
 167
 168         validated_shader->num_texture_samples = s + 1;
 169         validated_shader->texture_samples = temp_samples;
 170
 171         for (i = 0; i < 4; i++)
 172                 validation_state->tmu_setup[tmu].p_offset[i] = ~0;
 173
 174         return true;
 175 }
 176
 177 static bool
 178 check_tmu_write(struct vc4_validated_shader_info *validated_shader,
 179                 struct vc4_shader_validation_state *validation_state,
 180                 bool is_mul)
 181 {
 182         uint64_t inst = validation_state->shader[validation_state->ip];
 183         uint32_t waddr = (is_mul ?
 184                           QPU_GET_FIELD(inst, QPU_WADDR_MUL) :
 185                           QPU_GET_FIELD(inst, QPU_WADDR_ADD));
 186         uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
 187         uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
 188         int tmu = waddr > QPU_W_TMU0_B;
 189         bool submit = is_tmu_submit(waddr);
 190         bool is_direct = submit && validation_state->tmu_write_count[tmu] == 0;
 191         uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
 192
 193         if (is_direct) {
 194                 uint32_t add_b = QPU_GET_FIELD(inst, QPU_ADD_B);
 195                 uint32_t clamp_reg, clamp_offset;
 196
 197                 if (sig == QPU_SIG_SMALL_IMM) {
 198                         DRM_ERROR("direct TMU read used small immediate\n");
 199                         return false;
 200                 }
 201
 202                 /* Make sure that this texture load is an add of the base
 203                  * address of the UBO to a clamped offset within the UBO.
 204                  */
 205                 if (is_mul ||
 206                     QPU_GET_FIELD(inst, QPU_OP_ADD) != QPU_A_ADD) {
 207                         DRM_ERROR("direct TMU load wasn't an add\n");
 208                         return false;
 209                 }
 210
 211                 /* We assert that the clamped address is the first
 212                  * argument, and the UBO base address is the second argument.
 213                  * This is arbitrary, but simpler than supporting flipping the
 214                  * two either way.
 215                  */
 216                 clamp_reg = raddr_add_a_to_live_reg_index(inst);
 217                 if (clamp_reg == ~0) {
 218                         DRM_ERROR("direct TMU load wasn't clamped\n");
 219                         return false;
 220                 }
 221
 222                 clamp_offset = validation_state->live_min_clamp_offsets[clamp_reg];
 223                 if (clamp_offset == ~0) {
 224                         DRM_ERROR("direct TMU load wasn't clamped\n");
 225                         return false;
 226                 }
 227
 228                 /* Store the clamp value's offset in p1 (see reloc_tex() in
 229                  * vc4_validate.c).
 230                  */
 231                 validation_state->tmu_setup[tmu].p_offset[1] =
 232                         clamp_offset;
 233
 234                 if (!(add_b == QPU_MUX_A && raddr_a == QPU_R_UNIF) &&
 235                     !(add_b == QPU_MUX_B && raddr_b == QPU_R_UNIF)) {
 236                         DRM_ERROR("direct TMU load didn't add to a uniform\n");
 237                         return false;
 238                 }
 239
 240                 validation_state->tmu_setup[tmu].is_direct = true;
 241         } else {
 242                 if (raddr_a == QPU_R_UNIF || (sig != QPU_SIG_SMALL_IMM &&
 243                                               raddr_b == QPU_R_UNIF)) {
 244                         DRM_ERROR("uniform read in the same instruction as "
 245                                   "texture setup.\n");
 246                         return false;
 247                 }
 248         }
 249
 250         if (validation_state->tmu_write_count[tmu] >= 4) {
 251                 DRM_ERROR("TMU%d got too many parameters before dispatch\n",
 252                           tmu);
 253                 return false;
 254         }
 255         validation_state->tmu_setup[tmu].p_offset[validation_state->tmu_write_count[tmu]] =
 256                 validated_shader->uniforms_size;
 257         validation_state->tmu_write_count[tmu]++;
 258         /* Since direct uses a RADDR uniform reference, it will get counted in
 259          * check_instruction_reads()
 260          */
 261         if (!is_direct) {
 262                 if (validation_state->needs_uniform_address_update) {
 263                         DRM_ERROR("Texturing with undefined uniform address\n");
 264                         return false;
 265                 }
 266
 267                 validated_shader->uniforms_size += 4;
 268         }
 269
 270         if (submit) {
 271                 if (!record_texture_sample(validated_shader,
 272                                            validation_state, tmu)) {
 273                         return false;
 274                 }
 275
 276                 validation_state->tmu_write_count[tmu] = 0;
 277         }
 278
 279         return true;
 280 }
 281
 282 static bool require_uniform_address_uniform(struct vc4_validated_shader_info *validated_shader)
 283 {
 284         uint32_t o = validated_shader->num_uniform_addr_offsets;
 285         uint32_t num_uniforms = validated_shader->uniforms_size / 4;
 286
 287         validated_shader->uniform_addr_offsets =
 288                 krealloc(validated_shader->uniform_addr_offsets,
 289                          (o + 1) *
 290                          sizeof(*validated_shader->uniform_addr_offsets),
 291                          GFP_KERNEL);
 292         if (!validated_shader->uniform_addr_offsets)
 293                 return false;
 294
 295         validated_shader->uniform_addr_offsets[o] = num_uniforms;
 296         validated_shader->num_uniform_addr_offsets++;
 297
 298         return true;
 299 }
 300
 301 static bool
 302 validate_uniform_address_write(struct vc4_validated_shader_info *validated_shader,
 303                                struct vc4_shader_validation_state *validation_state,
 304                                bool is_mul)
 305 {
 306         uint64_t inst = validation_state->shader[validation_state->ip];
 307         u32 add_b = QPU_GET_FIELD(inst, QPU_ADD_B);
 308         u32 raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
 309         u32 raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
 310         u32 add_lri = raddr_add_a_to_live_reg_index(inst);
 311         /* We want our reset to be pointing at whatever uniform follows the
 312          * uniforms base address.
 313          */
 314         u32 expected_offset = validated_shader->uniforms_size + 4;
 315
 316         /* We only support absolute uniform address changes, and we
 317          * require that they be in the current basic block before any
 318          * of its uniform reads.
 319          *
 320          * One could potentially emit more efficient QPU code, by
 321          * noticing that (say) an if statement does uniform control
 322          * flow for all threads and that the if reads the same number
 323          * of uniforms on each side.  However, this scheme is easy to
 324          * validate so it's all we allow for now.
 325          */
 326         switch (QPU_GET_FIELD(inst, QPU_SIG)) {
 327         case QPU_SIG_NONE:
 328         case QPU_SIG_SCOREBOARD_UNLOCK:
 329         case QPU_SIG_COLOR_LOAD:
 330         case QPU_SIG_LOAD_TMU0:
 331         case QPU_SIG_LOAD_TMU1:
 332                 break;
 333         default:
 334                 DRM_ERROR("uniforms address change must be "
 335                           "normal math\n");
 336                 return false;
 337         }
 338
 339         if (is_mul || QPU_GET_FIELD(inst, QPU_OP_ADD) != QPU_A_ADD) {
 340                 DRM_ERROR("Uniform address reset must be an ADD.\n");
 341                 return false;
 342         }
 343
 344         if (QPU_GET_FIELD(inst, QPU_COND_ADD) != QPU_COND_ALWAYS) {
 345                 DRM_ERROR("Uniform address reset must be unconditional.\n");
 346                 return false;
 347         }
 348
 349         if (QPU_GET_FIELD(inst, QPU_PACK) != QPU_PACK_A_NOP &&
 350             !(inst & QPU_PM)) {
 351                 DRM_ERROR("No packing allowed on uniforms reset\n");
 352                 return false;
 353         }
 354
 355         if (add_lri == -1) {
 356                 DRM_ERROR("First argument of uniform address write must be "
 357                           "an immediate value.\n");
 358                 return false;
 359         }
 360
 361         if (validation_state->live_immediates[add_lri] != expected_offset) {
 362                 DRM_ERROR("Resetting uniforms with offset %db instead of %db\n",
 363                           validation_state->live_immediates[add_lri],
 364                           expected_offset);
 365                 return false;
 366         }
 367
 368         if (!(add_b == QPU_MUX_A && raddr_a == QPU_R_UNIF) &&
 369             !(add_b == QPU_MUX_B && raddr_b == QPU_R_UNIF)) {
 370                 DRM_ERROR("Second argument of uniform address write must be "
 371                           "a uniform.\n");
 372                 return false;
 373         }
 374
 375         validation_state->needs_uniform_address_update = false;
 376         validation_state->needs_uniform_address_for_loop = false;
 377         return require_uniform_address_uniform(validated_shader);
 378 }
 379
 380 static bool
 381 check_reg_write(struct vc4_validated_shader_info *validated_shader,
 382                 struct vc4_shader_validation_state *validation_state,
 383                 bool is_mul)
 384 {
 385         uint64_t inst = validation_state->shader[validation_state->ip];
 386         uint32_t waddr = (is_mul ?
 387                           QPU_GET_FIELD(inst, QPU_WADDR_MUL) :
 388                           QPU_GET_FIELD(inst, QPU_WADDR_ADD));
 389         uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
 390         bool ws = inst & QPU_WS;
 391         bool is_b = is_mul ^ ws;
 392         u32 lri = waddr_to_live_reg_index(waddr, is_b);
 393
 394         if (lri != -1) {
 395                 uint32_t cond_add = QPU_GET_FIELD(inst, QPU_COND_ADD);
 396                 uint32_t cond_mul = QPU_GET_FIELD(inst, QPU_COND_MUL);
 397
 398                 if (sig == QPU_SIG_LOAD_IMM &&
 399                     QPU_GET_FIELD(inst, QPU_PACK) == QPU_PACK_A_NOP &&
 400                     ((is_mul && cond_mul == QPU_COND_ALWAYS) ||
 401                      (!is_mul && cond_add == QPU_COND_ALWAYS))) {
 402                         validation_state->live_immediates[lri] =
 403                                 QPU_GET_FIELD(inst, QPU_LOAD_IMM);
 404                 } else {
 405                         validation_state->live_immediates[lri] = ~0;
 406                 }
 407
 408                 if (live_reg_is_upper_half(lri))
 409                         validation_state->all_registers_used = true;
 410         }
 411
 412         switch (waddr) {
 413         case QPU_W_UNIFORMS_ADDRESS:
 414                 if (is_b) {
 415                         DRM_ERROR("relative uniforms address change "
 416                                   "unsupported\n");
 417                         return false;
 418                 }
 419
 420                 return validate_uniform_address_write(validated_shader,
 421                                                       validation_state,
 422                                                       is_mul);
 423
 424         case QPU_W_TLB_COLOR_MS:
 425         case QPU_W_TLB_COLOR_ALL:
 426         case QPU_W_TLB_Z:
 427                 /* These only interact with the tile buffer, not main memory,
 428                  * so they're safe.
 429                  */
 430                 return true;
 431
 432         case QPU_W_TMU0_S:
 433         case QPU_W_TMU0_T:
 434         case QPU_W_TMU0_R:
 435         case QPU_W_TMU0_B:
 436         case QPU_W_TMU1_S:
 437         case QPU_W_TMU1_T:
 438         case QPU_W_TMU1_R:
 439         case QPU_W_TMU1_B:
 440                 return check_tmu_write(validated_shader, validation_state,
 441                                        is_mul);
 442
 443         case QPU_W_HOST_INT:
 444         case QPU_W_TMU_NOSWAP:
 445         case QPU_W_TLB_ALPHA_MASK:
 446         case QPU_W_MUTEX_RELEASE:
 447                 /* XXX: I haven't thought about these, so don't support them
 448                  * for now.
 449                  */
 450                 DRM_ERROR("Unsupported waddr %d\n", waddr);
 451                 return false;
 452
 453         case QPU_W_VPM_ADDR:
 454                 DRM_ERROR("General VPM DMA unsupported\n");
 455                 return false;
 456
 457         case QPU_W_VPM:
 458         case QPU_W_VPMVCD_SETUP:
 459                 /* We allow VPM setup in general, even including VPM DMA
 460                  * configuration setup, because the (unsafe) DMA can only be
 461                  * triggered by QPU_W_VPM_ADDR writes.
 462                  */
 463                 return true;
 464
 465         case QPU_W_TLB_STENCIL_SETUP:
 466                 return true;
 467         }
 468
 469         return true;
 470 }
 471
 472 static void
 473 track_live_clamps(struct vc4_validated_shader_info *validated_shader,
 474                   struct vc4_shader_validation_state *validation_state)
 475 {
 476         uint64_t inst = validation_state->shader[validation_state->ip];
 477         uint32_t op_add = QPU_GET_FIELD(inst, QPU_OP_ADD);
 478         uint32_t waddr_add = QPU_GET_FIELD(inst, QPU_WADDR_ADD);
 479         uint32_t waddr_mul = QPU_GET_FIELD(inst, QPU_WADDR_MUL);
 480         uint32_t cond_add = QPU_GET_FIELD(inst, QPU_COND_ADD);
 481         uint32_t add_a = QPU_GET_FIELD(inst, QPU_ADD_A);
 482         uint32_t add_b = QPU_GET_FIELD(inst, QPU_ADD_B);
 483         uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
 484         uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
 485         uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
 486         bool ws = inst & QPU_WS;
 487         uint32_t lri_add_a, lri_add, lri_mul;
 488         bool add_a_is_min_0;
 489
 490         /* Check whether OP_ADD's A argumennt comes from a live MAX(x, 0),
 491          * before we clear previous live state.
 492          */
 493         lri_add_a = raddr_add_a_to_live_reg_index(inst);
 494         add_a_is_min_0 = (lri_add_a != ~0 &&
 495                           validation_state->live_max_clamp_regs[lri_add_a]);
 496
 497         /* Clear live state for registers written by our instruction. */
 498         lri_add = waddr_to_live_reg_index(waddr_add, ws);
 499         lri_mul = waddr_to_live_reg_index(waddr_mul, !ws);
 500         if (lri_mul != ~0) {
 501                 validation_state->live_max_clamp_regs[lri_mul] = false;
 502                 validation_state->live_min_clamp_offsets[lri_mul] = ~0;
 503         }
 504         if (lri_add != ~0) {
 505                 validation_state->live_max_clamp_regs[lri_add] = false;
 506                 validation_state->live_min_clamp_offsets[lri_add] = ~0;
 507         } else {
 508                 /* Nothing further to do for live tracking, since only ADDs
 509                  * generate new live clamp registers.
 510                  */
 511                 return;
 512         }
 513
 514         /* Now, handle remaining live clamp tracking for the ADD operation. */
 515
 516         if (cond_add != QPU_COND_ALWAYS)
 517                 return;
 518
 519         if (op_add == QPU_A_MAX) {
 520                 /* Track live clamps of a value to a minimum of 0 (in either
 521                  * arg).
 522                  */
 523                 if (sig != QPU_SIG_SMALL_IMM || raddr_b != 0 ||
 524                     (add_a != QPU_MUX_B && add_b != QPU_MUX_B)) {
 525                         return;
 526                 }
 527
 528                 validation_state->live_max_clamp_regs[lri_add] = true;
 529         } else if (op_add == QPU_A_MIN) {
 530                 /* Track live clamps of a value clamped to a minimum of 0 and
 531                  * a maximum of some uniform's offset.
 532                  */
 533                 if (!add_a_is_min_0)
 534                         return;
 535
 536                 if (!(add_b == QPU_MUX_A && raddr_a == QPU_R_UNIF) &&
 537                     !(add_b == QPU_MUX_B && raddr_b == QPU_R_UNIF &&
 538                       sig != QPU_SIG_SMALL_IMM)) {
 539                         return;
 540                 }
 541
 542                 validation_state->live_min_clamp_offsets[lri_add] =
 543                         validated_shader->uniforms_size;
 544         }
 545 }
 546
 547 static bool
 548 check_instruction_writes(struct vc4_validated_shader_info *validated_shader,
 549                          struct vc4_shader_validation_state *validation_state)
 550 {
 551         uint64_t inst = validation_state->shader[validation_state->ip];
 552         uint32_t waddr_add = QPU_GET_FIELD(inst, QPU_WADDR_ADD);
 553         uint32_t waddr_mul = QPU_GET_FIELD(inst, QPU_WADDR_MUL);
 554         bool ok;
 555
 556         if (is_tmu_write(waddr_add) && is_tmu_write(waddr_mul)) {
 557                 DRM_ERROR("ADD and MUL both set up textures\n");
 558                 return false;
 559         }
 560
 561         ok = (check_reg_write(validated_shader, validation_state, false) &&
 562               check_reg_write(validated_shader, validation_state, true));
 563
 564         track_live_clamps(validated_shader, validation_state);
 565
 566         return ok;
 567 }
 568
 569 static bool
 570 check_branch(uint64_t inst,
 571              struct vc4_validated_shader_info *validated_shader,
 572              struct vc4_shader_validation_state *validation_state,
 573              int ip)
 574 {
 575         int32_t branch_imm = QPU_GET_FIELD(inst, QPU_BRANCH_TARGET);
 576         uint32_t waddr_add = QPU_GET_FIELD(inst, QPU_WADDR_ADD);
 577         uint32_t waddr_mul = QPU_GET_FIELD(inst, QPU_WADDR_MUL);
 578
 579         if ((int)branch_imm < 0)
 580                 validation_state->needs_uniform_address_for_loop = true;
 581
 582         /* We don't want to have to worry about validation of this, and
 583          * there's no need for it.
 584          */
 585         if (waddr_add != QPU_W_NOP || waddr_mul != QPU_W_NOP) {
 586                 DRM_ERROR("branch instruction at %d wrote a register.\n",
 587                           validation_state->ip);
 588                 return false;
 589         }
 590
 591         return true;
 592 }
 593
 594 static bool
 595 check_instruction_reads(struct vc4_validated_shader_info *validated_shader,
 596                         struct vc4_shader_validation_state *validation_state)
 597 {
 598         uint64_t inst = validation_state->shader[validation_state->ip];
 599         uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
 600         uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
 601         uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
 602
 603         if (raddr_a == QPU_R_UNIF ||
 604             (raddr_b == QPU_R_UNIF && sig != QPU_SIG_SMALL_IMM)) {
 605                 /* This can't overflow the uint32_t, because we're reading 8
 606                  * bytes of instruction to increment by 4 here, so we'd
 607                  * already be OOM.
 608                  */
 609                 validated_shader->uniforms_size += 4;
 610
 611                 if (validation_state->needs_uniform_address_update) {
 612                         DRM_ERROR("Uniform read with undefined uniform "
 613                                   "address\n");
 614                         return false;
 615                 }
 616         }
 617
 618         if ((raddr_a >= 16 && raddr_a < 32) ||
 619             (raddr_b >= 16 && raddr_b < 32 && sig != QPU_SIG_SMALL_IMM)) {
 620                 validation_state->all_registers_used = true;
 621         }
 622
 623         return true;
 624 }
 625
 626 /* Make sure that all branches are absolute and point within the shader, and
 627  * note their targets for later.
 628  */
 629 static bool
 630 vc4_validate_branches(struct vc4_shader_validation_state *validation_state)
 631 {
 632         uint32_t max_branch_target = 0;
 633         int ip;
 634         int last_branch = -2;
 635
 636         for (ip = 0; ip < validation_state->max_ip; ip++) {
 637                 uint64_t inst = validation_state->shader[ip];
 638                 int32_t branch_imm = QPU_GET_FIELD(inst, QPU_BRANCH_TARGET);
 639                 uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
 640                 uint32_t after_delay_ip = ip + 4;
 641                 uint32_t branch_target_ip;
 642
 643                 if (sig == QPU_SIG_PROG_END) {
 644                         /* There are two delay slots after program end is
 645                          * signaled that are still executed, then we're
 646                          * finished.  validation_state->max_ip is the
 647                          * instruction after the last valid instruction in the
 648                          * program.
 649                          */
 650                         validation_state->max_ip = ip + 3;
 651                         continue;
 652                 }
 653
 654                 if (sig != QPU_SIG_BRANCH)
 655                         continue;
 656
 657                 if (ip - last_branch < 4) {
 658                         DRM_ERROR("Branch at %d during delay slots\n", ip);
 659                         return false;
 660                 }
 661                 last_branch = ip;
 662
 663                 if (inst & QPU_BRANCH_REG) {
 664                         DRM_ERROR("branching from register relative "
 665                                   "not supported\n");
 666                         return false;
 667                 }
 668
 669                 if (!(inst & QPU_BRANCH_REL)) {
 670                         DRM_ERROR("relative branching required\n");
 671                         return false;
 672                 }
 673
 674                 /* The actual branch target is the instruction after the delay
 675                  * slots, plus whatever byte offset is in the low 32 bits of
 676                  * the instruction.  Make sure we're not branching beyond the
 677                  * end of the shader object.
 678                  */
 679                 if (branch_imm % sizeof(inst) != 0) {
 680                         DRM_ERROR("branch target not aligned\n");
 681                         return false;
 682                 }
 683
 684                 branch_target_ip = after_delay_ip + (branch_imm >> 3);
 685                 if (branch_target_ip >= validation_state->max_ip) {
 686                         DRM_ERROR("Branch at %d outside of shader (ip %d/%d)\n",
 687                                   ip, branch_target_ip,
 688                                   validation_state->max_ip);
 689                         return false;
 690                 }
 691                 set_bit(branch_target_ip, validation_state->branch_targets);
 692
 693                 /* Make sure that the non-branching path is also not outside
 694                  * the shader.
 695                  */
 696                 if (after_delay_ip >= validation_state->max_ip) {
 697                         DRM_ERROR("Branch at %d continues past shader end "
 698                                   "(%d/%d)\n",
 699                                   ip, after_delay_ip, validation_state->max_ip);
 700                         return false;
 701                 }
 702                 set_bit(after_delay_ip, validation_state->branch_targets);
 703                 max_branch_target = max(max_branch_target, after_delay_ip);
 704         }
 705
 706         if (max_branch_target > validation_state->max_ip - 3) {
 707                 DRM_ERROR("Branch landed after QPU_SIG_PROG_END");
 708                 return false;
 709         }
 710
 711         return true;
 712 }
 713
 714 /* Resets any known state for the shader, used when we may be branched to from
 715  * multiple locations in the program (or at shader start).
 716  */
 717 static void
 718 reset_validation_state(struct vc4_shader_validation_state *validation_state)
 719 {
 720         int i;
 721
 722         for (i = 0; i < 8; i++)
 723                 validation_state->tmu_setup[i / 4].p_offset[i % 4] = ~0;
 724
 725         for (i = 0; i < LIVE_REG_COUNT; i++) {
 726                 validation_state->live_min_clamp_offsets[i] = ~0;
 727                 validation_state->live_max_clamp_regs[i] = false;
 728                 validation_state->live_immediates[i] = ~0;
 729         }
 730 }
 731
 732 static bool
 733 texturing_in_progress(struct vc4_shader_validation_state *validation_state)
 734 {
 735         return (validation_state->tmu_write_count[0] != 0 ||
 736                 validation_state->tmu_write_count[1] != 0);
 737 }
 738
 739 static bool
 740 vc4_handle_branch_target(struct vc4_shader_validation_state *validation_state)
 741 {
 742         uint32_t ip = validation_state->ip;
 743
 744         if (!test_bit(ip, validation_state->branch_targets))
 745                 return true;
 746
 747         if (texturing_in_progress(validation_state)) {
 748                 DRM_ERROR("Branch target landed during TMU setup\n");
 749                 return false;
 750         }
 751
 752         /* Reset our live values tracking, since this instruction may have
 753          * multiple predecessors.
 754          *
 755          * One could potentially do analysis to determine that, for
 756          * example, all predecessors have a live max clamp in the same
 757          * register, but we don't bother with that.
 758          */
 759         reset_validation_state(validation_state);
 760
 761         /* Since we've entered a basic block from potentially multiple
 762          * predecessors, we need the uniforms address to be updated before any
 763          * unforms are read.  We require that after any branch point, the next
 764          * uniform to be loaded is a uniform address offset.  That uniform's
 765          * offset will be marked by the uniform address register write
 766          * validation, or a one-off the end-of-program check.
 767          */
 768         validation_state->needs_uniform_address_update = true;
 769
 770         return true;
 771 }
 772
 773 struct vc4_validated_shader_info *
 774 vc4_validate_shader(struct drm_gem_cma_object *shader_obj)
 775 {
 776         bool found_shader_end = false;
 777         int shader_end_ip = 0;
 778         uint32_t last_thread_switch_ip = -3;
 779         uint32_t ip;
 780         struct vc4_validated_shader_info *validated_shader = NULL;
 781         struct vc4_shader_validation_state validation_state;
 782
 783         memset(&validation_state, 0, sizeof(validation_state));
 784         validation_state.shader = shader_obj->vaddr;
 785         validation_state.max_ip = shader_obj->base.size / sizeof(uint64_t);
 786
 787         reset_validation_state(&validation_state);
 788
 789         validation_state.branch_targets =
 790                 kcalloc(BITS_TO_LONGS(validation_state.max_ip),
 791                         sizeof(unsigned long), GFP_KERNEL);
 792         if (!validation_state.branch_targets)
 793                 goto fail;
 794
 795         validated_shader = kcalloc(1, sizeof(*validated_shader), GFP_KERNEL);
 796         if (!validated_shader)
 797                 goto fail;
 798
 799         if (!vc4_validate_branches(&validation_state))
 800                 goto fail;
 801
 802         for (ip = 0; ip < validation_state.max_ip; ip++) {
 803                 uint64_t inst = validation_state.shader[ip];
 804                 uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
 805
 806                 validation_state.ip = ip;
 807
 808                 if (!vc4_handle_branch_target(&validation_state))
 809                         goto fail;
 810
 811                 if (ip == last_thread_switch_ip + 3) {
 812                         /* Reset r0-r3 live clamp data */
 813                         int i;
 814
 815                         for (i = 64; i < LIVE_REG_COUNT; i++) {
 816                                 validation_state.live_min_clamp_offsets[i] = ~0;
 817                                 validation_state.live_max_clamp_regs[i] = false;
 818                                 validation_state.live_immediates[i] = ~0;
 819                         }
 820                 }
 821
 822                 switch (sig) {
 823                 case QPU_SIG_NONE:
 824                 case QPU_SIG_WAIT_FOR_SCOREBOARD:
 825                 case QPU_SIG_SCOREBOARD_UNLOCK:
 826                 case QPU_SIG_COLOR_LOAD:
 827                 case QPU_SIG_LOAD_TMU0:
 828                 case QPU_SIG_LOAD_TMU1:
 829                 case QPU_SIG_PROG_END:
 830                 case QPU_SIG_SMALL_IMM:
 831                 case QPU_SIG_THREAD_SWITCH:
 832                 case QPU_SIG_LAST_THREAD_SWITCH:
 833                         if (!check_instruction_writes(validated_shader,
 834                                                       &validation_state)) {
 835                                 DRM_ERROR("Bad write at ip %d\n", ip);
 836                                 goto fail;
 837                         }
 838
 839                         if (!check_instruction_reads(validated_shader,
 840                                                      &validation_state))
 841                                 goto fail;
 842
 843                         if (sig == QPU_SIG_PROG_END) {
 844                                 found_shader_end = true;
 845                                 shader_end_ip = ip;
 846                         }
 847
 848                         if (sig == QPU_SIG_THREAD_SWITCH ||
 849                             sig == QPU_SIG_LAST_THREAD_SWITCH) {
 850                                 validated_shader->is_threaded = true;
 851
 852                                 if (ip < last_thread_switch_ip + 3) {
 853                                         DRM_ERROR("Thread switch too soon after "
 854                                                   "last switch at ip %d\n", ip);
 855                                         goto fail;
 856                                 }
 857                                 last_thread_switch_ip = ip;
 858                         }
 859
 860                         break;
 861
 862                 case QPU_SIG_LOAD_IMM:
 863                         if (!check_instruction_writes(validated_shader,
 864                                                       &validation_state)) {
 865                                 DRM_ERROR("Bad LOAD_IMM write at ip %d\n", ip);
 866                                 goto fail;
 867                         }
 868                         break;
 869
 870                 case QPU_SIG_BRANCH:
 871                         if (!check_branch(inst, validated_shader,
 872                                           &validation_state, ip))
 873                                 goto fail;
 874
 875                         if (ip < last_thread_switch_ip + 3) {
 876                                 DRM_ERROR("Branch in thread switch at ip %d",
 877                                           ip);
 878                                 goto fail;
 879                         }
 880
 881                         break;
 882                 default:
 883                         DRM_ERROR("Unsupported QPU signal %d at "
 884                                   "instruction %d\n", sig, ip);
 885                         goto fail;
 886                 }
 887
 888                 /* There are two delay slots after program end is signaled
 889                  * that are still executed, then we're finished.
 890                  */
 891                 if (found_shader_end && ip == shader_end_ip + 2)
 892                         break;
 893         }
 894
 895         if (ip == validation_state.max_ip) {
 896                 DRM_ERROR("shader failed to terminate before "
 897                           "shader BO end at %zd\n",
 898                           shader_obj->base.size);
 899                 goto fail;
 900         }
 901
 902         /* Might corrupt other thread */
 903         if (validated_shader->is_threaded &&
 904             validation_state.all_registers_used) {
 905                 DRM_ERROR("Shader uses threading, but uses the upper "
 906                           "half of the registers, too\n");
 907                 goto fail;
 908         }
 909
 910         /* If we did a backwards branch and we haven't emitted a uniforms
 911          * reset since then, we still need the uniforms stream to have the
 912          * uniforms address available so that the backwards branch can do its
 913          * uniforms reset.
 914          *
 915          * We could potentially prove that the backwards branch doesn't
 916          * contain any uses of uniforms until program exit, but that doesn't
 917          * seem to be worth the trouble.
 918          */
 919         if (validation_state.needs_uniform_address_for_loop) {
 920                 if (!require_uniform_address_uniform(validated_shader))
 921                         goto fail;
 922                 validated_shader->uniforms_size += 4;
 923         }
 924
 925         /* Again, no chance of integer overflow here because the worst case
 926          * scenario is 8 bytes of uniforms plus handles per 8-byte
 927          * instruction.
 928          */
 929         validated_shader->uniforms_src_size =
 930                 (validated_shader->uniforms_size +
 931                  4 * validated_shader->num_texture_samples);
 932
 933         kfree(validation_state.branch_targets);
 934
 935         return validated_shader;
 936
 937 fail:
 938         kfree(validation_state.branch_targets);
 939         if (validated_shader) {
 940                 kfree(validated_shader->texture_samples);
 941                 kfree(validated_shader);
 942         }
 943         return NULL;
 944 }