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 struct vc4_shader_validation_state {
  43         struct vc4_texture_sample_info tmu_setup[2];
  44         int tmu_write_count[2];
  45
  46         /* For registers that were last written to by a MIN instruction with
  47          * one argument being a uniform, the address of the uniform.
  48          * Otherwise, ~0.
  49          *
  50          * This is used for the validation of direct address memory reads.
  51          */
  52         uint32_t live_min_clamp_offsets[32 + 32 + 4];
  53         bool live_max_clamp_regs[32 + 32 + 4];
  54 };
  55
  56 static uint32_t
  57 waddr_to_live_reg_index(uint32_t waddr, bool is_b)
  58 {
  59         if (waddr < 32) {
  60                 if (is_b)
  61                         return 32 + waddr;
  62                 else
  63                         return waddr;
  64         } else if (waddr <= QPU_W_ACC3) {
  65                 return 64 + waddr - QPU_W_ACC0;
  66         } else {
  67                 return ~0;
  68         }
  69 }
  70
  71 static uint32_t
  72 raddr_add_a_to_live_reg_index(uint64_t inst)
  73 {
  74         uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
  75         uint32_t add_a = QPU_GET_FIELD(inst, QPU_ADD_A);
  76         uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
  77         uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
  78
  79         if (add_a == QPU_MUX_A)
  80                 return raddr_a;
  81         else if (add_a == QPU_MUX_B && sig != QPU_SIG_SMALL_IMM)
  82                 return 32 + raddr_b;
  83         else if (add_a <= QPU_MUX_R3)
  84                 return 64 + add_a;
  85         else
  86                 return ~0;
  87 }
  88
  89 static bool
  90 is_tmu_submit(uint32_t waddr)
  91 {
  92         return (waddr == QPU_W_TMU0_S ||
  93                 waddr == QPU_W_TMU1_S);
  94 }
  95
  96 static bool
  97 is_tmu_write(uint32_t waddr)
  98 {
  99         return (waddr >= QPU_W_TMU0_S &&
 100                 waddr <= QPU_W_TMU1_B);
 101 }
 102
 103 static bool
 104 record_texture_sample(struct vc4_validated_shader_info *validated_shader,
 105                       struct vc4_shader_validation_state *validation_state,
 106                       int tmu)
 107 {
 108         uint32_t s = validated_shader->num_texture_samples;
 109         int i;
 110         struct vc4_texture_sample_info *temp_samples;
 111
 112         temp_samples = krealloc(validated_shader->texture_samples,
 113                                 (s + 1) * sizeof(*temp_samples),
 114                                 GFP_KERNEL);
 115         if (!temp_samples)
 116                 return false;
 117
 118         memcpy(&temp_samples[s],
 119                &validation_state->tmu_setup[tmu],
 120                sizeof(*temp_samples));
 121
 122         validated_shader->num_texture_samples = s + 1;
 123         validated_shader->texture_samples = temp_samples;
 124
 125         for (i = 0; i < 4; i++)
 126                 validation_state->tmu_setup[tmu].p_offset[i] = ~0;
 127
 128         return true;
 129 }
 130
 131 static bool
 132 check_tmu_write(uint64_t inst,
 133                 struct vc4_validated_shader_info *validated_shader,
 134                 struct vc4_shader_validation_state *validation_state,
 135                 bool is_mul)
 136 {
 137         uint32_t waddr = (is_mul ?
 138                           QPU_GET_FIELD(inst, QPU_WADDR_MUL) :
 139                           QPU_GET_FIELD(inst, QPU_WADDR_ADD));
 140         uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
 141         uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
 142         int tmu = waddr > QPU_W_TMU0_B;
 143         bool submit = is_tmu_submit(waddr);
 144         bool is_direct = submit && validation_state->tmu_write_count[tmu] == 0;
 145         uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
 146
 147         if (is_direct) {
 148                 uint32_t add_b = QPU_GET_FIELD(inst, QPU_ADD_B);
 149                 uint32_t clamp_reg, clamp_offset;
 150
 151                 if (sig == QPU_SIG_SMALL_IMM) {
 152                         DRM_ERROR("direct TMU read used small immediate\n");
 153                         return false;
 154                 }
 155
 156                 /* Make sure that this texture load is an add of the base
 157                  * address of the UBO to a clamped offset within the UBO.
 158                  */
 159                 if (is_mul ||
 160                     QPU_GET_FIELD(inst, QPU_OP_ADD) != QPU_A_ADD) {
 161                         DRM_ERROR("direct TMU load wasn't an add\n");
 162                         return false;
 163                 }
 164
 165                 /* We assert that the the clamped address is the first
 166                  * argument, and the UBO base address is the second argument.
 167                  * This is arbitrary, but simpler than supporting flipping the
 168                  * two either way.
 169                  */
 170                 clamp_reg = raddr_add_a_to_live_reg_index(inst);
 171                 if (clamp_reg == ~0) {
 172                         DRM_ERROR("direct TMU load wasn't clamped\n");
 173                         return false;
 174                 }
 175
 176                 clamp_offset = validation_state->live_min_clamp_offsets[clamp_reg];
 177                 if (clamp_offset == ~0) {
 178                         DRM_ERROR("direct TMU load wasn't clamped\n");
 179                         return false;
 180                 }
 181
 182                 /* Store the clamp value's offset in p1 (see reloc_tex() in
 183                  * vc4_validate.c).
 184                  */
 185                 validation_state->tmu_setup[tmu].p_offset[1] =
 186                         clamp_offset;
 187
 188                 if (!(add_b == QPU_MUX_A && raddr_a == QPU_R_UNIF) &&
 189                     !(add_b == QPU_MUX_B && raddr_b == QPU_R_UNIF)) {
 190                         DRM_ERROR("direct TMU load didn't add to a uniform\n");
 191                         return false;
 192                 }
 193
 194                 validation_state->tmu_setup[tmu].is_direct = true;
 195         } else {
 196                 if (raddr_a == QPU_R_UNIF || (sig != QPU_SIG_SMALL_IMM &&
 197                                               raddr_b == QPU_R_UNIF)) {
 198                         DRM_ERROR("uniform read in the same instruction as "
 199                                   "texture setup.\n");
 200                         return false;
 201                 }
 202         }
 203
 204         if (validation_state->tmu_write_count[tmu] >= 4) {
 205                 DRM_ERROR("TMU%d got too many parameters before dispatch\n",
 206                           tmu);
 207                 return false;
 208         }
 209         validation_state->tmu_setup[tmu].p_offset[validation_state->tmu_write_count[tmu]] =
 210                 validated_shader->uniforms_size;
 211         validation_state->tmu_write_count[tmu]++;
 212         /* Since direct uses a RADDR uniform reference, it will get counted in
 213          * check_instruction_reads()
 214          */
 215         if (!is_direct)
 216                 validated_shader->uniforms_size += 4;
 217
 218         if (submit) {
 219                 if (!record_texture_sample(validated_shader,
 220                                            validation_state, tmu)) {
 221                         return false;
 222                 }
 223
 224                 validation_state->tmu_write_count[tmu] = 0;
 225         }
 226
 227         return true;
 228 }
 229
 230 static bool
 231 check_reg_write(uint64_t inst,
 232                 struct vc4_validated_shader_info *validated_shader,
 233                 struct vc4_shader_validation_state *validation_state,
 234                 bool is_mul)
 235 {
 236         uint32_t waddr = (is_mul ?
 237                           QPU_GET_FIELD(inst, QPU_WADDR_MUL) :
 238                           QPU_GET_FIELD(inst, QPU_WADDR_ADD));
 239
 240         switch (waddr) {
 241         case QPU_W_UNIFORMS_ADDRESS:
 242                 /* XXX: We'll probably need to support this for reladdr, but
 243                  * it's definitely a security-related one.
 244                  */
 245                 DRM_ERROR("uniforms address load unsupported\n");
 246                 return false;
 247
 248         case QPU_W_TLB_COLOR_MS:
 249         case QPU_W_TLB_COLOR_ALL:
 250         case QPU_W_TLB_Z:
 251                 /* These only interact with the tile buffer, not main memory,
 252                  * so they're safe.
 253                  */
 254                 return true;
 255
 256         case QPU_W_TMU0_S:
 257         case QPU_W_TMU0_T:
 258         case QPU_W_TMU0_R:
 259         case QPU_W_TMU0_B:
 260         case QPU_W_TMU1_S:
 261         case QPU_W_TMU1_T:
 262         case QPU_W_TMU1_R:
 263         case QPU_W_TMU1_B:
 264                 return check_tmu_write(inst, validated_shader, validation_state,
 265                                        is_mul);
 266
 267         case QPU_W_HOST_INT:
 268         case QPU_W_TMU_NOSWAP:
 269         case QPU_W_TLB_ALPHA_MASK:
 270         case QPU_W_MUTEX_RELEASE:
 271                 /* XXX: I haven't thought about these, so don't support them
 272                  * for now.
 273                  */
 274                 DRM_ERROR("Unsupported waddr %d\n", waddr);
 275                 return false;
 276
 277         case QPU_W_VPM_ADDR:
 278                 DRM_ERROR("General VPM DMA unsupported\n");
 279                 return false;
 280
 281         case QPU_W_VPM:
 282         case QPU_W_VPMVCD_SETUP:
 283                 /* We allow VPM setup in general, even including VPM DMA
 284                  * configuration setup, because the (unsafe) DMA can only be
 285                  * triggered by QPU_W_VPM_ADDR writes.
 286                  */
 287                 return true;
 288
 289         case QPU_W_TLB_STENCIL_SETUP:
 290                 return true;
 291         }
 292
 293         return true;
 294 }
 295
 296 static void
 297 track_live_clamps(uint64_t inst,
 298                   struct vc4_validated_shader_info *validated_shader,
 299                   struct vc4_shader_validation_state *validation_state)
 300 {
 301         uint32_t op_add = QPU_GET_FIELD(inst, QPU_OP_ADD);
 302         uint32_t waddr_add = QPU_GET_FIELD(inst, QPU_WADDR_ADD);
 303         uint32_t waddr_mul = QPU_GET_FIELD(inst, QPU_WADDR_MUL);
 304         uint32_t cond_add = QPU_GET_FIELD(inst, QPU_COND_ADD);
 305         uint32_t add_a = QPU_GET_FIELD(inst, QPU_ADD_A);
 306         uint32_t add_b = QPU_GET_FIELD(inst, QPU_ADD_B);
 307         uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
 308         uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
 309         uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
 310         bool ws = inst & QPU_WS;
 311         uint32_t lri_add_a, lri_add, lri_mul;
 312         bool add_a_is_min_0;
 313
 314         /* Check whether OP_ADD's A argumennt comes from a live MAX(x, 0),
 315          * before we clear previous live state.
 316          */
 317         lri_add_a = raddr_add_a_to_live_reg_index(inst);
 318         add_a_is_min_0 = (lri_add_a != ~0 &&
 319                           validation_state->live_max_clamp_regs[lri_add_a]);
 320
 321         /* Clear live state for registers written by our instruction. */
 322         lri_add = waddr_to_live_reg_index(waddr_add, ws);
 323         lri_mul = waddr_to_live_reg_index(waddr_mul, !ws);
 324         if (lri_mul != ~0) {
 325                 validation_state->live_max_clamp_regs[lri_mul] = false;
 326                 validation_state->live_min_clamp_offsets[lri_mul] = ~0;
 327         }
 328         if (lri_add != ~0) {
 329                 validation_state->live_max_clamp_regs[lri_add] = false;
 330                 validation_state->live_min_clamp_offsets[lri_add] = ~0;
 331         } else {
 332                 /* Nothing further to do for live tracking, since only ADDs
 333                  * generate new live clamp registers.
 334                  */
 335                 return;
 336         }
 337
 338         /* Now, handle remaining live clamp tracking for the ADD operation. */
 339
 340         if (cond_add != QPU_COND_ALWAYS)
 341                 return;
 342
 343         if (op_add == QPU_A_MAX) {
 344                 /* Track live clamps of a value to a minimum of 0 (in either
 345                  * arg).
 346                  */
 347                 if (sig != QPU_SIG_SMALL_IMM || raddr_b != 0 ||
 348                     (add_a != QPU_MUX_B && add_b != QPU_MUX_B)) {
 349                         return;
 350                 }
 351
 352                 validation_state->live_max_clamp_regs[lri_add] = true;
 353         } else if (op_add == QPU_A_MIN) {
 354                 /* Track live clamps of a value clamped to a minimum of 0 and
 355                  * a maximum of some uniform's offset.
 356                  */
 357                 if (!add_a_is_min_0)
 358                         return;
 359
 360                 if (!(add_b == QPU_MUX_A && raddr_a == QPU_R_UNIF) &&
 361                     !(add_b == QPU_MUX_B && raddr_b == QPU_R_UNIF &&
 362                       sig != QPU_SIG_SMALL_IMM)) {
 363                         return;
 364                 }
 365
 366                 validation_state->live_min_clamp_offsets[lri_add] =
 367                         validated_shader->uniforms_size;
 368         }
 369 }
 370
 371 static bool
 372 check_instruction_writes(uint64_t inst,
 373                          struct vc4_validated_shader_info *validated_shader,
 374                          struct vc4_shader_validation_state *validation_state)
 375 {
 376         uint32_t waddr_add = QPU_GET_FIELD(inst, QPU_WADDR_ADD);
 377         uint32_t waddr_mul = QPU_GET_FIELD(inst, QPU_WADDR_MUL);
 378         bool ok;
 379
 380         if (is_tmu_write(waddr_add) && is_tmu_write(waddr_mul)) {
 381                 DRM_ERROR("ADD and MUL both set up textures\n");
 382                 return false;
 383         }
 384
 385         ok = (check_reg_write(inst, validated_shader, validation_state,
 386                               false) &&
 387               check_reg_write(inst, validated_shader, validation_state,
 388                               true));
 389
 390         track_live_clamps(inst, validated_shader, validation_state);
 391
 392         return ok;
 393 }
 394
 395 static bool
 396 check_instruction_reads(uint64_t inst,
 397                         struct vc4_validated_shader_info *validated_shader)
 398 {
 399         uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
 400         uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
 401         uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
 402
 403         if (raddr_a == QPU_R_UNIF ||
 404             (raddr_b == QPU_R_UNIF && sig != QPU_SIG_SMALL_IMM)) {
 405                 /* This can't overflow the uint32_t, because we're reading 8
 406                  * bytes of instruction to increment by 4 here, so we'd
 407                  * already be OOM.
 408                  */
 409                 validated_shader->uniforms_size += 4;
 410         }
 411
 412         return true;
 413 }
 414
 415 struct vc4_validated_shader_info *
 416 vc4_validate_shader(struct drm_gem_cma_object *shader_obj)
 417 {
 418         bool found_shader_end = false;
 419         int shader_end_ip = 0;
 420         uint32_t ip, max_ip;
 421         uint64_t *shader;
 422         struct vc4_validated_shader_info *validated_shader;
 423         struct vc4_shader_validation_state validation_state;
 424         int i;
 425
 426         memset(&validation_state, 0, sizeof(validation_state));
 427
 428         for (i = 0; i < 8; i++)
 429                 validation_state.tmu_setup[i / 4].p_offset[i % 4] = ~0;
 430         for (i = 0; i < ARRAY_SIZE(validation_state.live_min_clamp_offsets); i++)
 431                 validation_state.live_min_clamp_offsets[i] = ~0;
 432
 433         shader = shader_obj->vaddr;
 434         max_ip = shader_obj->base.size / sizeof(uint64_t);
 435
 436         validated_shader = kcalloc(1, sizeof(*validated_shader), GFP_KERNEL);
 437         if (!validated_shader)
 438                 return NULL;
 439
 440         for (ip = 0; ip < max_ip; ip++) {
 441                 uint64_t inst = shader[ip];
 442                 uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
 443
 444                 switch (sig) {
 445                 case QPU_SIG_NONE:
 446                 case QPU_SIG_WAIT_FOR_SCOREBOARD:
 447                 case QPU_SIG_SCOREBOARD_UNLOCK:
 448                 case QPU_SIG_COLOR_LOAD:
 449                 case QPU_SIG_LOAD_TMU0:
 450                 case QPU_SIG_LOAD_TMU1:
 451                 case QPU_SIG_PROG_END:
 452                 case QPU_SIG_SMALL_IMM:
 453                         if (!check_instruction_writes(inst, validated_shader,
 454                                                       &validation_state)) {
 455                                 DRM_ERROR("Bad write at ip %d\n", ip);
 456                                 goto fail;
 457                         }
 458
 459                         if (!check_instruction_reads(inst, validated_shader))
 460                                 goto fail;
 461
 462                         if (sig == QPU_SIG_PROG_END) {
 463                                 found_shader_end = true;
 464                                 shader_end_ip = ip;
 465                         }
 466
 467                         break;
 468
 469                 case QPU_SIG_LOAD_IMM:
 470                         if (!check_instruction_writes(inst, validated_shader,
 471                                                       &validation_state)) {
 472                                 DRM_ERROR("Bad LOAD_IMM write at ip %d\n", ip);
 473                                 goto fail;
 474                         }
 475                         break;
 476
 477                 default:
 478                         DRM_ERROR("Unsupported QPU signal %d at "
 479                                   "instruction %d\n", sig, ip);
 480                         goto fail;
 481                 }
 482
 483                 /* There are two delay slots after program end is signaled
 484                  * that are still executed, then we're finished.
 485                  */
 486                 if (found_shader_end && ip == shader_end_ip + 2)
 487                         break;
 488         }
 489
 490         if (ip == max_ip) {
 491                 DRM_ERROR("shader failed to terminate before "
 492                           "shader BO end at %zd\n",
 493                           shader_obj->base.size);
 494                 goto fail;
 495         }
 496
 497         /* Again, no chance of integer overflow here because the worst case
 498          * scenario is 8 bytes of uniforms plus handles per 8-byte
 499          * instruction.
 500          */
 501         validated_shader->uniforms_src_size =
 502                 (validated_shader->uniforms_size +
 503                  4 * validated_shader->num_texture_samples);
 504
 505         return validated_shader;
 506
 507 fail:
 508         if (validated_shader) {
 509                 kfree(validated_shader->texture_samples);
 510                 kfree(validated_shader);
 511         }
 512         return NULL;
 513 }