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 * Since the VC4 has no IOMMU between it and system memory, a user
28 * with access to execute shaders could escalate privilege by
29 * overwriting system memory (using the VPM write address register in
30 * the general-purpose DMA mode) or reading system memory it shouldn't
31 * (reading it as a texture, uniform data, or direct-addressed TMU
32 * lookup).
33 *
34 * The shader validator walks over a shader's BO, ensuring that its
35 * accesses are appropriately bounded, and recording where texture
36 * accesses are made so that we can do relocations for them in the
37 * uniform stream.
38 *
39 * Shader BO are immutable for their lifetimes (enforced by not
40 * allowing mmaps, GEM prime export, or rendering to from a CL), so
41 * this validation is only performed at BO creation time.
42 */
43
44#include "vc4_drv.h"
45#include "vc4_qpu_defines.h"
46
47#define LIVE_REG_COUNT (32 + 32 + 4)
48
49struct vc4_shader_validation_state {
50 /* Current IP being validated. */
51 uint32_t ip;
52
53 /* IP at the end of the BO, do not read shader[max_ip] */
54 uint32_t max_ip;
55
56 uint64_t *shader;
57
58 struct vc4_texture_sample_info tmu_setup[2];
59 int tmu_write_count[2];
60
61 /* For registers that were last written to by a MIN instruction with
62 * one argument being a uniform, the address of the uniform.
63 * Otherwise, ~0.
64 *
65 * This is used for the validation of direct address memory reads.
66 */
67 uint32_t live_min_clamp_offsets[LIVE_REG_COUNT];
68 bool live_max_clamp_regs[LIVE_REG_COUNT];
69 uint32_t live_immediates[LIVE_REG_COUNT];
70
71 /* Bitfield of which IPs are used as branch targets.
72 *
73 * Used for validation that the uniform stream is updated at the right
74 * points and clearing the texturing/clamping state.
75 */
76 unsigned long *branch_targets;
77
78 /* Set when entering a basic block, and cleared when the uniform
79 * address update is found. This is used to make sure that we don't
80 * read uniforms when the address is undefined.
81 */
82 bool needs_uniform_address_update;
83
84 /* Set when we find a backwards branch. If the branch is backwards,
85 * the taraget is probably doing an address reset to read uniforms,
86 * and so we need to be sure that a uniforms address is present in the
87 * stream, even if the shader didn't need to read uniforms in later
88 * basic blocks.
89 */
90 bool needs_uniform_address_for_loop;
91
92 /* Set when we find an instruction writing the top half of the
93 * register files. If we allowed writing the unusable regs in
94 * a threaded shader, then the other shader running on our
95 * QPU's clamp validation would be invalid.
96 */
97 bool all_registers_used;
98};
99
100static uint32_t
101waddr_to_live_reg_index(uint32_t waddr, bool is_b)
102{
103 if (waddr < 32) {
104 if (is_b)
105 return 32 + waddr;
106 else
107 return waddr;
108 } else if (waddr <= QPU_W_ACC3) {
109 return 64 + waddr - QPU_W_ACC0;
110 } else {
111 return ~0;
112 }
113}
114
115static uint32_t
116raddr_add_a_to_live_reg_index(uint64_t inst)
117{
118 uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
119 uint32_t add_a = QPU_GET_FIELD(inst, QPU_ADD_A);
120 uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
121 uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
122
123 if (add_a == QPU_MUX_A)
124 return raddr_a;
125 else if (add_a == QPU_MUX_B && sig != QPU_SIG_SMALL_IMM)
126 return 32 + raddr_b;
127 else if (add_a <= QPU_MUX_R3)
128 return 64 + add_a;
129 else
130 return ~0;
131}
132
133static bool
134live_reg_is_upper_half(uint32_t lri)
135{
136 return (lri >= 16 && lri < 32) ||
137 (lri >= 32 + 16 && lri < 32 + 32);
138}
139
140static bool
141is_tmu_submit(uint32_t waddr)
142{
143 return (waddr == QPU_W_TMU0_S ||
144 waddr == QPU_W_TMU1_S);
145}
146
147static bool
148is_tmu_write(uint32_t waddr)
149{
150 return (waddr >= QPU_W_TMU0_S &&
151 waddr <= QPU_W_TMU1_B);
152}
153
154static bool
155record_texture_sample(struct vc4_validated_shader_info *validated_shader,
156 struct vc4_shader_validation_state *validation_state,
157 int tmu)
158{
159 uint32_t s = validated_shader->num_texture_samples;
160 int i;
161 struct vc4_texture_sample_info *temp_samples;
162
163 temp_samples = krealloc(objp: validated_shader->texture_samples,
164 new_size: (s + 1) * sizeof(*temp_samples),
165 GFP_KERNEL);
166 if (!temp_samples)
167 return false;
168
169 memcpy(&temp_samples[s],
170 &validation_state->tmu_setup[tmu],
171 sizeof(*temp_samples));
172
173 validated_shader->num_texture_samples = s + 1;
174 validated_shader->texture_samples = temp_samples;
175
176 for (i = 0; i < 4; i++)
177 validation_state->tmu_setup[tmu].p_offset[i] = ~0;
178
179 return true;
180}
181
182static bool
183check_tmu_write(struct vc4_validated_shader_info *validated_shader,
184 struct vc4_shader_validation_state *validation_state,
185 bool is_mul)
186{
187 uint64_t inst = validation_state->shader[validation_state->ip];
188 uint32_t waddr = (is_mul ?
189 QPU_GET_FIELD(inst, QPU_WADDR_MUL) :
190 QPU_GET_FIELD(inst, QPU_WADDR_ADD));
191 uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
192 uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
193 int tmu = waddr > QPU_W_TMU0_B;
194 bool submit = is_tmu_submit(waddr);
195 bool is_direct = submit && validation_state->tmu_write_count[tmu] == 0;
196 uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
197
198 if (is_direct) {
199 uint32_t add_b = QPU_GET_FIELD(inst, QPU_ADD_B);
200 uint32_t clamp_reg, clamp_offset;
201
202 if (sig == QPU_SIG_SMALL_IMM) {
203 DRM_DEBUG("direct TMU read used small immediate\n");
204 return false;
205 }
206
207 /* Make sure that this texture load is an add of the base
208 * address of the UBO to a clamped offset within the UBO.
209 */
210 if (is_mul ||
211 QPU_GET_FIELD(inst, QPU_OP_ADD) != QPU_A_ADD) {
212 DRM_DEBUG("direct TMU load wasn't an add\n");
213 return false;
214 }
215
216 /* We assert that the clamped address is the first
217 * argument, and the UBO base address is the second argument.
218 * This is arbitrary, but simpler than supporting flipping the
219 * two either way.
220 */
221 clamp_reg = raddr_add_a_to_live_reg_index(inst);
222 if (clamp_reg == ~0) {
223 DRM_DEBUG("direct TMU load wasn't clamped\n");
224 return false;
225 }
226
227 clamp_offset = validation_state->live_min_clamp_offsets[clamp_reg];
228 if (clamp_offset == ~0) {
229 DRM_DEBUG("direct TMU load wasn't clamped\n");
230 return false;
231 }
232
233 /* Store the clamp value's offset in p1 (see reloc_tex() in
234 * vc4_validate.c).
235 */
236 validation_state->tmu_setup[tmu].p_offset[1] =
237 clamp_offset;
238
239 if (!(add_b == QPU_MUX_A && raddr_a == QPU_R_UNIF) &&
240 !(add_b == QPU_MUX_B && raddr_b == QPU_R_UNIF)) {
241 DRM_DEBUG("direct TMU load didn't add to a uniform\n");
242 return false;
243 }
244
245 validation_state->tmu_setup[tmu].is_direct = true;
246 } else {
247 if (raddr_a == QPU_R_UNIF || (sig != QPU_SIG_SMALL_IMM &&
248 raddr_b == QPU_R_UNIF)) {
249 DRM_DEBUG("uniform read in the same instruction as "
250 "texture setup.\n");
251 return false;
252 }
253 }
254
255 if (validation_state->tmu_write_count[tmu] >= 4) {
256 DRM_DEBUG("TMU%d got too many parameters before dispatch\n",
257 tmu);
258 return false;
259 }
260 validation_state->tmu_setup[tmu].p_offset[validation_state->tmu_write_count[tmu]] =
261 validated_shader->uniforms_size;
262 validation_state->tmu_write_count[tmu]++;
263 /* Since direct uses a RADDR uniform reference, it will get counted in
264 * check_instruction_reads()
265 */
266 if (!is_direct) {
267 if (validation_state->needs_uniform_address_update) {
268 DRM_DEBUG("Texturing with undefined uniform address\n");
269 return false;
270 }
271
272 validated_shader->uniforms_size += 4;
273 }
274
275 if (submit) {
276 if (!record_texture_sample(validated_shader,
277 validation_state, tmu)) {
278 return false;
279 }
280
281 validation_state->tmu_write_count[tmu] = 0;
282 }
283
284 return true;
285}
286
287static bool require_uniform_address_uniform(struct vc4_validated_shader_info *validated_shader)
288{
289 uint32_t o = validated_shader->num_uniform_addr_offsets;
290 uint32_t num_uniforms = validated_shader->uniforms_size / 4;
291
292 validated_shader->uniform_addr_offsets =
293 krealloc(objp: validated_shader->uniform_addr_offsets,
294 new_size: (o + 1) *
295 sizeof(*validated_shader->uniform_addr_offsets),
296 GFP_KERNEL);
297 if (!validated_shader->uniform_addr_offsets)
298 return false;
299
300 validated_shader->uniform_addr_offsets[o] = num_uniforms;
301 validated_shader->num_uniform_addr_offsets++;
302
303 return true;
304}
305
306static bool
307validate_uniform_address_write(struct vc4_validated_shader_info *validated_shader,
308 struct vc4_shader_validation_state *validation_state,
309 bool is_mul)
310{
311 uint64_t inst = validation_state->shader[validation_state->ip];
312 u32 add_b = QPU_GET_FIELD(inst, QPU_ADD_B);
313 u32 raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
314 u32 raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
315 u32 add_lri = raddr_add_a_to_live_reg_index(inst);
316 /* We want our reset to be pointing at whatever uniform follows the
317 * uniforms base address.
318 */
319 u32 expected_offset = validated_shader->uniforms_size + 4;
320
321 /* We only support absolute uniform address changes, and we
322 * require that they be in the current basic block before any
323 * of its uniform reads.
324 *
325 * One could potentially emit more efficient QPU code, by
326 * noticing that (say) an if statement does uniform control
327 * flow for all threads and that the if reads the same number
328 * of uniforms on each side. However, this scheme is easy to
329 * validate so it's all we allow for now.
330 */
331 switch (QPU_GET_FIELD(inst, QPU_SIG)) {
332 case QPU_SIG_NONE:
333 case QPU_SIG_SCOREBOARD_UNLOCK:
334 case QPU_SIG_COLOR_LOAD:
335 case QPU_SIG_LOAD_TMU0:
336 case QPU_SIG_LOAD_TMU1:
337 break;
338 default:
339 DRM_DEBUG("uniforms address change must be "
340 "normal math\n");
341 return false;
342 }
343
344 if (is_mul || QPU_GET_FIELD(inst, QPU_OP_ADD) != QPU_A_ADD) {
345 DRM_DEBUG("Uniform address reset must be an ADD.\n");
346 return false;
347 }
348
349 if (QPU_GET_FIELD(inst, QPU_COND_ADD) != QPU_COND_ALWAYS) {
350 DRM_DEBUG("Uniform address reset must be unconditional.\n");
351 return false;
352 }
353
354 if (QPU_GET_FIELD(inst, QPU_PACK) != QPU_PACK_A_NOP &&
355 !(inst & QPU_PM)) {
356 DRM_DEBUG("No packing allowed on uniforms reset\n");
357 return false;
358 }
359
360 if (add_lri == -1) {
361 DRM_DEBUG("First argument of uniform address write must be "
362 "an immediate value.\n");
363 return false;
364 }
365
366 if (validation_state->live_immediates[add_lri] != expected_offset) {
367 DRM_DEBUG("Resetting uniforms with offset %db instead of %db\n",
368 validation_state->live_immediates[add_lri],
369 expected_offset);
370 return false;
371 }
372
373 if (!(add_b == QPU_MUX_A && raddr_a == QPU_R_UNIF) &&
374 !(add_b == QPU_MUX_B && raddr_b == QPU_R_UNIF)) {
375 DRM_DEBUG("Second argument of uniform address write must be "
376 "a uniform.\n");
377 return false;
378 }
379
380 validation_state->needs_uniform_address_update = false;
381 validation_state->needs_uniform_address_for_loop = false;
382 return require_uniform_address_uniform(validated_shader);
383}
384
385static bool
386check_reg_write(struct vc4_validated_shader_info *validated_shader,
387 struct vc4_shader_validation_state *validation_state,
388 bool is_mul)
389{
390 uint64_t inst = validation_state->shader[validation_state->ip];
391 uint32_t waddr = (is_mul ?
392 QPU_GET_FIELD(inst, QPU_WADDR_MUL) :
393 QPU_GET_FIELD(inst, QPU_WADDR_ADD));
394 uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
395 bool ws = inst & QPU_WS;
396 bool is_b = is_mul ^ ws;
397 u32 lri = waddr_to_live_reg_index(waddr, is_b);
398
399 if (lri != -1) {
400 uint32_t cond_add = QPU_GET_FIELD(inst, QPU_COND_ADD);
401 uint32_t cond_mul = QPU_GET_FIELD(inst, QPU_COND_MUL);
402
403 if (sig == QPU_SIG_LOAD_IMM &&
404 QPU_GET_FIELD(inst, QPU_PACK) == QPU_PACK_A_NOP &&
405 ((is_mul && cond_mul == QPU_COND_ALWAYS) ||
406 (!is_mul && cond_add == QPU_COND_ALWAYS))) {
407 validation_state->live_immediates[lri] =
408 QPU_GET_FIELD(inst, QPU_LOAD_IMM);
409 } else {
410 validation_state->live_immediates[lri] = ~0;
411 }
412
413 if (live_reg_is_upper_half(lri))
414 validation_state->all_registers_used = true;
415 }
416
417 switch (waddr) {
418 case QPU_W_UNIFORMS_ADDRESS:
419 if (is_b) {
420 DRM_DEBUG("relative uniforms address change "
421 "unsupported\n");
422 return false;
423 }
424
425 return validate_uniform_address_write(validated_shader,
426 validation_state,
427 is_mul);
428
429 case QPU_W_TLB_COLOR_MS:
430 case QPU_W_TLB_COLOR_ALL:
431 case QPU_W_TLB_Z:
432 /* These only interact with the tile buffer, not main memory,
433 * so they're safe.
434 */
435 return true;
436
437 case QPU_W_TMU0_S:
438 case QPU_W_TMU0_T:
439 case QPU_W_TMU0_R:
440 case QPU_W_TMU0_B:
441 case QPU_W_TMU1_S:
442 case QPU_W_TMU1_T:
443 case QPU_W_TMU1_R:
444 case QPU_W_TMU1_B:
445 return check_tmu_write(validated_shader, validation_state,
446 is_mul);
447
448 case QPU_W_HOST_INT:
449 case QPU_W_TMU_NOSWAP:
450 case QPU_W_TLB_ALPHA_MASK:
451 case QPU_W_MUTEX_RELEASE:
452 /* XXX: I haven't thought about these, so don't support them
453 * for now.
454 */
455 DRM_DEBUG("Unsupported waddr %d\n", waddr);
456 return false;
457
458 case QPU_W_VPM_ADDR:
459 DRM_DEBUG("General VPM DMA unsupported\n");
460 return false;
461
462 case QPU_W_VPM:
463 case QPU_W_VPMVCD_SETUP:
464 /* We allow VPM setup in general, even including VPM DMA
465 * configuration setup, because the (unsafe) DMA can only be
466 * triggered by QPU_W_VPM_ADDR writes.
467 */
468 return true;
469
470 case QPU_W_TLB_STENCIL_SETUP:
471 return true;
472 }
473
474 return true;
475}
476
477static void
478track_live_clamps(struct vc4_validated_shader_info *validated_shader,
479 struct vc4_shader_validation_state *validation_state)
480{
481 uint64_t inst = validation_state->shader[validation_state->ip];
482 uint32_t op_add = QPU_GET_FIELD(inst, QPU_OP_ADD);
483 uint32_t waddr_add = QPU_GET_FIELD(inst, QPU_WADDR_ADD);
484 uint32_t waddr_mul = QPU_GET_FIELD(inst, QPU_WADDR_MUL);
485 uint32_t cond_add = QPU_GET_FIELD(inst, QPU_COND_ADD);
486 uint32_t add_a = QPU_GET_FIELD(inst, QPU_ADD_A);
487 uint32_t add_b = QPU_GET_FIELD(inst, QPU_ADD_B);
488 uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
489 uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
490 uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
491 bool ws = inst & QPU_WS;
492 uint32_t lri_add_a, lri_add, lri_mul;
493 bool add_a_is_min_0;
494
495 /* Check whether OP_ADD's A argumennt comes from a live MAX(x, 0),
496 * before we clear previous live state.
497 */
498 lri_add_a = raddr_add_a_to_live_reg_index(inst);
499 add_a_is_min_0 = (lri_add_a != ~0 &&
500 validation_state->live_max_clamp_regs[lri_add_a]);
501
502 /* Clear live state for registers written by our instruction. */
503 lri_add = waddr_to_live_reg_index(waddr: waddr_add, is_b: ws);
504 lri_mul = waddr_to_live_reg_index(waddr: waddr_mul, is_b: !ws);
505 if (lri_mul != ~0) {
506 validation_state->live_max_clamp_regs[lri_mul] = false;
507 validation_state->live_min_clamp_offsets[lri_mul] = ~0;
508 }
509 if (lri_add != ~0) {
510 validation_state->live_max_clamp_regs[lri_add] = false;
511 validation_state->live_min_clamp_offsets[lri_add] = ~0;
512 } else {
513 /* Nothing further to do for live tracking, since only ADDs
514 * generate new live clamp registers.
515 */
516 return;
517 }
518
519 /* Now, handle remaining live clamp tracking for the ADD operation. */
520
521 if (cond_add != QPU_COND_ALWAYS)
522 return;
523
524 if (op_add == QPU_A_MAX) {
525 /* Track live clamps of a value to a minimum of 0 (in either
526 * arg).
527 */
528 if (sig != QPU_SIG_SMALL_IMM || raddr_b != 0 ||
529 (add_a != QPU_MUX_B && add_b != QPU_MUX_B)) {
530 return;
531 }
532
533 validation_state->live_max_clamp_regs[lri_add] = true;
534 } else if (op_add == QPU_A_MIN) {
535 /* Track live clamps of a value clamped to a minimum of 0 and
536 * a maximum of some uniform's offset.
537 */
538 if (!add_a_is_min_0)
539 return;
540
541 if (!(add_b == QPU_MUX_A && raddr_a == QPU_R_UNIF) &&
542 !(add_b == QPU_MUX_B && raddr_b == QPU_R_UNIF &&
543 sig != QPU_SIG_SMALL_IMM)) {
544 return;
545 }
546
547 validation_state->live_min_clamp_offsets[lri_add] =
548 validated_shader->uniforms_size;
549 }
550}
551
552static bool
553check_instruction_writes(struct vc4_validated_shader_info *validated_shader,
554 struct vc4_shader_validation_state *validation_state)
555{
556 uint64_t inst = validation_state->shader[validation_state->ip];
557 uint32_t waddr_add = QPU_GET_FIELD(inst, QPU_WADDR_ADD);
558 uint32_t waddr_mul = QPU_GET_FIELD(inst, QPU_WADDR_MUL);
559 bool ok;
560
561 if (is_tmu_write(waddr: waddr_add) && is_tmu_write(waddr: waddr_mul)) {
562 DRM_DEBUG("ADD and MUL both set up textures\n");
563 return false;
564 }
565
566 ok = (check_reg_write(validated_shader, validation_state, is_mul: false) &&
567 check_reg_write(validated_shader, validation_state, is_mul: true));
568
569 track_live_clamps(validated_shader, validation_state);
570
571 return ok;
572}
573
574static bool
575check_branch(uint64_t inst,
576 struct vc4_validated_shader_info *validated_shader,
577 struct vc4_shader_validation_state *validation_state,
578 int ip)
579{
580 int32_t branch_imm = QPU_GET_FIELD(inst, QPU_BRANCH_TARGET);
581 uint32_t waddr_add = QPU_GET_FIELD(inst, QPU_WADDR_ADD);
582 uint32_t waddr_mul = QPU_GET_FIELD(inst, QPU_WADDR_MUL);
583
584 if ((int)branch_imm < 0)
585 validation_state->needs_uniform_address_for_loop = true;
586
587 /* We don't want to have to worry about validation of this, and
588 * there's no need for it.
589 */
590 if (waddr_add != QPU_W_NOP || waddr_mul != QPU_W_NOP) {
591 DRM_DEBUG("branch instruction at %d wrote a register.\n",
592 validation_state->ip);
593 return false;
594 }
595
596 return true;
597}
598
599static bool
600check_instruction_reads(struct vc4_validated_shader_info *validated_shader,
601 struct vc4_shader_validation_state *validation_state)
602{
603 uint64_t inst = validation_state->shader[validation_state->ip];
604 uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
605 uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
606 uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
607
608 if (raddr_a == QPU_R_UNIF ||
609 (raddr_b == QPU_R_UNIF && sig != QPU_SIG_SMALL_IMM)) {
610 /* This can't overflow the uint32_t, because we're reading 8
611 * bytes of instruction to increment by 4 here, so we'd
612 * already be OOM.
613 */
614 validated_shader->uniforms_size += 4;
615
616 if (validation_state->needs_uniform_address_update) {
617 DRM_DEBUG("Uniform read with undefined uniform "
618 "address\n");
619 return false;
620 }
621 }
622
623 if ((raddr_a >= 16 && raddr_a < 32) ||
624 (raddr_b >= 16 && raddr_b < 32 && sig != QPU_SIG_SMALL_IMM)) {
625 validation_state->all_registers_used = true;
626 }
627
628 return true;
629}
630
631/* Make sure that all branches are absolute and point within the shader, and
632 * note their targets for later.
633 */
634static bool
635vc4_validate_branches(struct vc4_shader_validation_state *validation_state)
636{
637 uint32_t max_branch_target = 0;
638 int ip;
639 int last_branch = -2;
640
641 for (ip = 0; ip < validation_state->max_ip; ip++) {
642 uint64_t inst = validation_state->shader[ip];
643 int32_t branch_imm = QPU_GET_FIELD(inst, QPU_BRANCH_TARGET);
644 uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
645 uint32_t after_delay_ip = ip + 4;
646 uint32_t branch_target_ip;
647
648 if (sig == QPU_SIG_PROG_END) {
649 /* There are two delay slots after program end is
650 * signaled that are still executed, then we're
651 * finished. validation_state->max_ip is the
652 * instruction after the last valid instruction in the
653 * program.
654 */
655 validation_state->max_ip = ip + 3;
656 continue;
657 }
658
659 if (sig != QPU_SIG_BRANCH)
660 continue;
661
662 if (ip - last_branch < 4) {
663 DRM_DEBUG("Branch at %d during delay slots\n", ip);
664 return false;
665 }
666 last_branch = ip;
667
668 if (inst & QPU_BRANCH_REG) {
669 DRM_DEBUG("branching from register relative "
670 "not supported\n");
671 return false;
672 }
673
674 if (!(inst & QPU_BRANCH_REL)) {
675 DRM_DEBUG("relative branching required\n");
676 return false;
677 }
678
679 /* The actual branch target is the instruction after the delay
680 * slots, plus whatever byte offset is in the low 32 bits of
681 * the instruction. Make sure we're not branching beyond the
682 * end of the shader object.
683 */
684 if (branch_imm % sizeof(inst) != 0) {
685 DRM_DEBUG("branch target not aligned\n");
686 return false;
687 }
688
689 branch_target_ip = after_delay_ip + (branch_imm >> 3);
690 if (branch_target_ip >= validation_state->max_ip) {
691 DRM_DEBUG("Branch at %d outside of shader (ip %d/%d)\n",
692 ip, branch_target_ip,
693 validation_state->max_ip);
694 return false;
695 }
696 set_bit(nr: branch_target_ip, addr: validation_state->branch_targets);
697
698 /* Make sure that the non-branching path is also not outside
699 * the shader.
700 */
701 if (after_delay_ip >= validation_state->max_ip) {
702 DRM_DEBUG("Branch at %d continues past shader end "
703 "(%d/%d)\n",
704 ip, after_delay_ip, validation_state->max_ip);
705 return false;
706 }
707 set_bit(nr: after_delay_ip, addr: validation_state->branch_targets);
708 max_branch_target = max(max_branch_target, after_delay_ip);
709 }
710
711 if (max_branch_target > validation_state->max_ip - 3) {
712 DRM_DEBUG("Branch landed after QPU_SIG_PROG_END");
713 return false;
714 }
715
716 return true;
717}
718
719/* Resets any known state for the shader, used when we may be branched to from
720 * multiple locations in the program (or at shader start).
721 */
722static void
723reset_validation_state(struct vc4_shader_validation_state *validation_state)
724{
725 int i;
726
727 for (i = 0; i < 8; i++)
728 validation_state->tmu_setup[i / 4].p_offset[i % 4] = ~0;
729
730 for (i = 0; i < LIVE_REG_COUNT; i++) {
731 validation_state->live_min_clamp_offsets[i] = ~0;
732 validation_state->live_max_clamp_regs[i] = false;
733 validation_state->live_immediates[i] = ~0;
734 }
735}
736
737static bool
738texturing_in_progress(struct vc4_shader_validation_state *validation_state)
739{
740 return (validation_state->tmu_write_count[0] != 0 ||
741 validation_state->tmu_write_count[1] != 0);
742}
743
744static bool
745vc4_handle_branch_target(struct vc4_shader_validation_state *validation_state)
746{
747 uint32_t ip = validation_state->ip;
748
749 if (!test_bit(ip, validation_state->branch_targets))
750 return true;
751
752 if (texturing_in_progress(validation_state)) {
753 DRM_DEBUG("Branch target landed during TMU setup\n");
754 return false;
755 }
756
757 /* Reset our live values tracking, since this instruction may have
758 * multiple predecessors.
759 *
760 * One could potentially do analysis to determine that, for
761 * example, all predecessors have a live max clamp in the same
762 * register, but we don't bother with that.
763 */
764 reset_validation_state(validation_state);
765
766 /* Since we've entered a basic block from potentially multiple
767 * predecessors, we need the uniforms address to be updated before any
768 * unforms are read. We require that after any branch point, the next
769 * uniform to be loaded is a uniform address offset. That uniform's
770 * offset will be marked by the uniform address register write
771 * validation, or a one-off the end-of-program check.
772 */
773 validation_state->needs_uniform_address_update = true;
774
775 return true;
776}
777
778struct vc4_validated_shader_info *
779vc4_validate_shader(struct drm_gem_dma_object *shader_obj)
780{
781 struct vc4_dev *vc4 = to_vc4_dev(shader_obj->base.dev);
782 bool found_shader_end = false;
783 int shader_end_ip = 0;
784 uint32_t last_thread_switch_ip = -3;
785 uint32_t ip;
786 struct vc4_validated_shader_info *validated_shader = NULL;
787 struct vc4_shader_validation_state validation_state;
788
789 if (WARN_ON_ONCE(vc4->is_vc5))
790 return NULL;
791
792 memset(&validation_state, 0, sizeof(validation_state));
793 validation_state.shader = shader_obj->vaddr;
794 validation_state.max_ip = shader_obj->base.size / sizeof(uint64_t);
795
796 reset_validation_state(validation_state: &validation_state);
797
798 validation_state.branch_targets =
799 kcalloc(BITS_TO_LONGS(validation_state.max_ip),
800 size: sizeof(unsigned long), GFP_KERNEL);
801 if (!validation_state.branch_targets)
802 goto fail;
803
804 validated_shader = kcalloc(n: 1, size: sizeof(*validated_shader), GFP_KERNEL);
805 if (!validated_shader)
806 goto fail;
807
808 if (!vc4_validate_branches(validation_state: &validation_state))
809 goto fail;
810
811 for (ip = 0; ip < validation_state.max_ip; ip++) {
812 uint64_t inst = validation_state.shader[ip];
813 uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
814
815 validation_state.ip = ip;
816
817 if (!vc4_handle_branch_target(validation_state: &validation_state))
818 goto fail;
819
820 if (ip == last_thread_switch_ip + 3) {
821 /* Reset r0-r3 live clamp data */
822 int i;
823
824 for (i = 64; i < LIVE_REG_COUNT; i++) {
825 validation_state.live_min_clamp_offsets[i] = ~0;
826 validation_state.live_max_clamp_regs[i] = false;
827 validation_state.live_immediates[i] = ~0;
828 }
829 }
830
831 switch (sig) {
832 case QPU_SIG_NONE:
833 case QPU_SIG_WAIT_FOR_SCOREBOARD:
834 case QPU_SIG_SCOREBOARD_UNLOCK:
835 case QPU_SIG_COLOR_LOAD:
836 case QPU_SIG_LOAD_TMU0:
837 case QPU_SIG_LOAD_TMU1:
838 case QPU_SIG_PROG_END:
839 case QPU_SIG_SMALL_IMM:
840 case QPU_SIG_THREAD_SWITCH:
841 case QPU_SIG_LAST_THREAD_SWITCH:
842 if (!check_instruction_writes(validated_shader,
843 validation_state: &validation_state)) {
844 DRM_DEBUG("Bad write at ip %d\n", ip);
845 goto fail;
846 }
847
848 if (!check_instruction_reads(validated_shader,
849 validation_state: &validation_state))
850 goto fail;
851
852 if (sig == QPU_SIG_PROG_END) {
853 found_shader_end = true;
854 shader_end_ip = ip;
855 }
856
857 if (sig == QPU_SIG_THREAD_SWITCH ||
858 sig == QPU_SIG_LAST_THREAD_SWITCH) {
859 validated_shader->is_threaded = true;
860
861 if (ip < last_thread_switch_ip + 3) {
862 DRM_DEBUG("Thread switch too soon after "
863 "last switch at ip %d\n", ip);
864 goto fail;
865 }
866 last_thread_switch_ip = ip;
867 }
868
869 break;
870
871 case QPU_SIG_LOAD_IMM:
872 if (!check_instruction_writes(validated_shader,
873 validation_state: &validation_state)) {
874 DRM_DEBUG("Bad LOAD_IMM write at ip %d\n", ip);
875 goto fail;
876 }
877 break;
878
879 case QPU_SIG_BRANCH:
880 if (!check_branch(inst, validated_shader,
881 validation_state: &validation_state, ip))
882 goto fail;
883
884 if (ip < last_thread_switch_ip + 3) {
885 DRM_DEBUG("Branch in thread switch at ip %d",
886 ip);
887 goto fail;
888 }
889
890 break;
891 default:
892 DRM_DEBUG("Unsupported QPU signal %d at "
893 "instruction %d\n", sig, ip);
894 goto fail;
895 }
896
897 /* There are two delay slots after program end is signaled
898 * that are still executed, then we're finished.
899 */
900 if (found_shader_end && ip == shader_end_ip + 2)
901 break;
902 }
903
904 if (ip == validation_state.max_ip) {
905 DRM_DEBUG("shader failed to terminate before "
906 "shader BO end at %zd\n",
907 shader_obj->base.size);
908 goto fail;
909 }
910
911 /* Might corrupt other thread */
912 if (validated_shader->is_threaded &&
913 validation_state.all_registers_used) {
914 DRM_DEBUG("Shader uses threading, but uses the upper "
915 "half of the registers, too\n");
916 goto fail;
917 }
918
919 /* If we did a backwards branch and we haven't emitted a uniforms
920 * reset since then, we still need the uniforms stream to have the
921 * uniforms address available so that the backwards branch can do its
922 * uniforms reset.
923 *
924 * We could potentially prove that the backwards branch doesn't
925 * contain any uses of uniforms until program exit, but that doesn't
926 * seem to be worth the trouble.
927 */
928 if (validation_state.needs_uniform_address_for_loop) {
929 if (!require_uniform_address_uniform(validated_shader))
930 goto fail;
931 validated_shader->uniforms_size += 4;
932 }
933
934 /* Again, no chance of integer overflow here because the worst case
935 * scenario is 8 bytes of uniforms plus handles per 8-byte
936 * instruction.
937 */
938 validated_shader->uniforms_src_size =
939 (validated_shader->uniforms_size +
940 4 * validated_shader->num_texture_samples);
941
942 kfree(objp: validation_state.branch_targets);
943
944 return validated_shader;
945
946fail:
947 kfree(objp: validation_state.branch_targets);
948 if (validated_shader) {
949 kfree(objp: validated_shader->uniform_addr_offsets);
950 kfree(objp: validated_shader->texture_samples);
951 kfree(objp: validated_shader);
952 }
953 return NULL;
954}
955

source code of linux/drivers/gpu/drm/vc4/vc4_validate_shaders.c