1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * eBPF JIT compiler 4 * 5 * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> 6 * IBM Corporation 7 * 8 * Based on the powerpc classic BPF JIT compiler by Matt Evans 9 */ 10 #include <linux/moduleloader.h> 11 #include <asm/cacheflush.h> 12 #include <asm/asm-compat.h> 13 #include <linux/netdevice.h> 14 #include <linux/filter.h> 15 #include <linux/if_vlan.h> 16 #include <linux/kernel.h> 17 #include <linux/memory.h> 18 #include <linux/bpf.h> 19 20 #include <asm/kprobes.h> 21 #include <asm/text-patching.h> 22 23 #include "bpf_jit.h" 24 25 /* These offsets are from bpf prog end and stay the same across progs */ 26 static int bpf_jit_ool_stub, bpf_jit_long_branch_stub; 27 28 static void bpf_jit_fill_ill_insns(void *area, unsigned int size) 29 { 30 memset32(area, BREAKPOINT_INSTRUCTION, size / 4); 31 } 32 33 void dummy_tramp(void); 34 35 asm ( 36 " .pushsection .text, \"ax\", @progbits ;" 37 " .global dummy_tramp ;" 38 " .type dummy_tramp, @function ;" 39 "dummy_tramp: ;" 40 #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE 41 " blr ;" 42 #else 43 /* LR is always in r11, so we don't need a 'mflr r11' here */ 44 " mtctr 11 ;" 45 " mtlr 0 ;" 46 " bctr ;" 47 #endif 48 " .size dummy_tramp, .-dummy_tramp ;" 49 " .popsection ;" 50 ); 51 52 void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx) 53 { 54 int ool_stub_idx, long_branch_stub_idx; 55 56 /* 57 * Out-of-line stub: 58 * mflr r0 59 * [b|bl] tramp 60 * mtlr r0 // only with CONFIG_PPC_FTRACE_OUT_OF_LINE 61 * b bpf_func + 4 62 */ 63 ool_stub_idx = ctx->idx; 64 EMIT(PPC_RAW_MFLR(_R0)); 65 EMIT(PPC_RAW_NOP()); 66 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) 67 EMIT(PPC_RAW_MTLR(_R0)); 68 WARN_ON_ONCE(!is_offset_in_branch_range(4 - (long)ctx->idx * 4)); 69 EMIT(PPC_RAW_BRANCH(4 - (long)ctx->idx * 4)); 70 71 /* 72 * Long branch stub: 73 * .long <dummy_tramp_addr> 74 * mflr r11 75 * bcl 20,31,$+4 76 * mflr r12 77 * ld r12, -8-SZL(r12) 78 * mtctr r12 79 * mtlr r11 // needed to retain ftrace ABI 80 * bctr 81 */ 82 if (image) 83 *((unsigned long *)&image[ctx->idx]) = (unsigned long)dummy_tramp; 84 ctx->idx += SZL / 4; 85 long_branch_stub_idx = ctx->idx; 86 EMIT(PPC_RAW_MFLR(_R11)); 87 EMIT(PPC_RAW_BCL4()); 88 EMIT(PPC_RAW_MFLR(_R12)); 89 EMIT(PPC_RAW_LL(_R12, _R12, -8-SZL)); 90 EMIT(PPC_RAW_MTCTR(_R12)); 91 EMIT(PPC_RAW_MTLR(_R11)); 92 EMIT(PPC_RAW_BCTR()); 93 94 if (!bpf_jit_ool_stub) { 95 bpf_jit_ool_stub = (ctx->idx - ool_stub_idx) * 4; 96 bpf_jit_long_branch_stub = (ctx->idx - long_branch_stub_idx) * 4; 97 } 98 } 99 100 int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr) 101 { 102 if (!exit_addr || is_offset_in_branch_range(exit_addr - (ctx->idx * 4))) { 103 PPC_JMP(exit_addr); 104 } else if (ctx->alt_exit_addr) { 105 if (WARN_ON(!is_offset_in_branch_range((long)ctx->alt_exit_addr - (ctx->idx * 4)))) 106 return -1; 107 PPC_JMP(ctx->alt_exit_addr); 108 } else { 109 ctx->alt_exit_addr = ctx->idx * 4; 110 bpf_jit_build_epilogue(image, ctx); 111 } 112 113 return 0; 114 } 115 116 struct powerpc_jit_data { 117 /* address of rw header */ 118 struct bpf_binary_header *hdr; 119 /* address of ro final header */ 120 struct bpf_binary_header *fhdr; 121 u32 *addrs; 122 u8 *fimage; 123 u32 proglen; 124 struct codegen_context ctx; 125 }; 126 127 bool bpf_jit_needs_zext(void) 128 { 129 return true; 130 } 131 132 static void priv_stack_init_guard(void __percpu *priv_stack_ptr, int alloc_size) 133 { 134 int cpu, underflow_idx = (alloc_size - PRIV_STACK_GUARD_SZ) >> 3; 135 u64 *stack_ptr; 136 137 for_each_possible_cpu(cpu) { 138 stack_ptr = per_cpu_ptr(priv_stack_ptr, cpu); 139 stack_ptr[0] = PRIV_STACK_GUARD_VAL; 140 stack_ptr[1] = PRIV_STACK_GUARD_VAL; 141 stack_ptr[underflow_idx] = PRIV_STACK_GUARD_VAL; 142 stack_ptr[underflow_idx + 1] = PRIV_STACK_GUARD_VAL; 143 } 144 } 145 146 static void priv_stack_check_guard(void __percpu *priv_stack_ptr, int alloc_size, 147 struct bpf_prog *fp) 148 { 149 int cpu, underflow_idx = (alloc_size - PRIV_STACK_GUARD_SZ) >> 3; 150 u64 *stack_ptr; 151 152 for_each_possible_cpu(cpu) { 153 stack_ptr = per_cpu_ptr(priv_stack_ptr, cpu); 154 if (stack_ptr[0] != PRIV_STACK_GUARD_VAL || 155 stack_ptr[1] != PRIV_STACK_GUARD_VAL || 156 stack_ptr[underflow_idx] != PRIV_STACK_GUARD_VAL || 157 stack_ptr[underflow_idx + 1] != PRIV_STACK_GUARD_VAL) { 158 pr_err("BPF private stack overflow/underflow detected for prog %s\n", 159 bpf_jit_get_prog_name(fp)); 160 break; 161 } 162 } 163 } 164 165 struct bpf_prog *bpf_int_jit_compile(struct bpf_verifier_env *env, struct bpf_prog *fp) 166 { 167 u32 proglen; 168 u32 alloclen; 169 u8 *image = NULL; 170 u32 *code_base = NULL; 171 u32 *addrs = NULL; 172 struct powerpc_jit_data *jit_data = NULL; 173 struct codegen_context cgctx; 174 int pass; 175 int flen; 176 int priv_stack_alloc_size; 177 void __percpu *priv_stack_ptr = NULL; 178 struct bpf_binary_header *fhdr = NULL; 179 struct bpf_binary_header *hdr = NULL; 180 bool extra_pass = false; 181 u8 *fimage = NULL; 182 u32 *fcode_base = NULL; 183 u32 extable_len; 184 u32 fixup_len; 185 186 if (!fp->jit_requested) 187 return fp; 188 189 jit_data = fp->aux->jit_data; 190 if (!jit_data) { 191 jit_data = kzalloc_obj(*jit_data); 192 if (!jit_data) 193 return fp; 194 fp->aux->jit_data = jit_data; 195 } 196 197 priv_stack_ptr = fp->aux->priv_stack_ptr; 198 if (!priv_stack_ptr && fp->aux->jits_use_priv_stack) { 199 /* 200 * Allocate private stack of size equivalent to 201 * verifier-calculated stack size plus two memory 202 * guard regions to detect private stack overflow 203 * and underflow. 204 */ 205 priv_stack_alloc_size = round_up(fp->aux->stack_depth, 16) + 206 2 * PRIV_STACK_GUARD_SZ; 207 priv_stack_ptr = __alloc_percpu_gfp(priv_stack_alloc_size, 16, GFP_KERNEL); 208 if (!priv_stack_ptr) 209 goto out_priv_stack; 210 211 priv_stack_init_guard(priv_stack_ptr, priv_stack_alloc_size); 212 fp->aux->priv_stack_ptr = priv_stack_ptr; 213 } 214 215 flen = fp->len; 216 addrs = jit_data->addrs; 217 if (addrs) { 218 cgctx = jit_data->ctx; 219 /* 220 * JIT compiled to a writable location (image/code_base) first. 221 * It is then moved to the readonly final location (fimage/fcode_base) 222 * using instruction patching. 223 */ 224 fimage = jit_data->fimage; 225 fhdr = jit_data->fhdr; 226 proglen = jit_data->proglen; 227 hdr = jit_data->hdr; 228 image = (void *)hdr + ((void *)fimage - (void *)fhdr); 229 extra_pass = true; 230 /* During extra pass, ensure index is reset before repopulating extable entries */ 231 cgctx.exentry_idx = 0; 232 goto skip_init_ctx; 233 } 234 235 addrs = kcalloc(flen + 1, sizeof(*addrs), GFP_KERNEL); 236 if (addrs == NULL) 237 goto out_err; 238 239 memset(&cgctx, 0, sizeof(struct codegen_context)); 240 bpf_jit_init_reg_mapping(&cgctx); 241 242 /* Make sure that the stack is quadword aligned. */ 243 cgctx.stack_size = round_up(fp->aux->stack_depth, 16); 244 cgctx.arena_vm_start = bpf_arena_get_kern_vm_start(fp->aux->arena); 245 cgctx.user_vm_start = bpf_arena_get_user_vm_start(fp->aux->arena); 246 cgctx.is_subprog = bpf_is_subprog(fp); 247 cgctx.exception_boundary = fp->aux->exception_boundary; 248 cgctx.exception_cb = fp->aux->exception_cb; 249 cgctx.priv_sp = priv_stack_ptr; 250 cgctx.priv_stack_size = 0; 251 if (priv_stack_ptr) { 252 /* 253 * priv_stack_size required for setting bpf FP inside 254 * percpu allocation. 255 * stack_size is marked 0 to prevent allocation on 256 * general stack and offset calculation don't go for 257 * a toss in bpf_jit_stack_offsetof() & bpf_jit_stack_local() 258 */ 259 cgctx.priv_stack_size = cgctx.stack_size; 260 cgctx.stack_size = 0; 261 } 262 263 /* Scouting faux-generate pass 0 */ 264 if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) 265 /* We hit something illegal or unsupported. */ 266 goto out_err; 267 268 /* 269 * If we have seen a tail call, we need a second pass. 270 * This is because bpf_jit_emit_common_epilogue() is called 271 * from bpf_jit_emit_tail_call() with a not yet stable ctx->seen. 272 * We also need a second pass if we ended up with too large 273 * a program so as to ensure BPF_EXIT branches are in range. 274 */ 275 if (cgctx.seen & SEEN_TAILCALL || !is_offset_in_branch_range((long)cgctx.idx * 4)) { 276 cgctx.idx = 0; 277 if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) 278 goto out_err; 279 } 280 281 bpf_jit_realloc_regs(&cgctx); 282 /* 283 * Pretend to build prologue, given the features we've seen. This will 284 * update ctgtx.idx as it pretends to output instructions, then we can 285 * calculate total size from idx. 286 */ 287 bpf_jit_build_prologue(NULL, &cgctx); 288 addrs[fp->len] = cgctx.idx * 4; 289 bpf_jit_build_epilogue(NULL, &cgctx); 290 291 fixup_len = fp->aux->num_exentries * BPF_FIXUP_LEN * 4; 292 extable_len = fp->aux->num_exentries * sizeof(struct exception_table_entry); 293 294 proglen = cgctx.idx * 4; 295 alloclen = proglen + FUNCTION_DESCR_SIZE + fixup_len + extable_len; 296 297 fhdr = bpf_jit_binary_pack_alloc(alloclen, &fimage, 4, &hdr, &image, 298 bpf_jit_fill_ill_insns); 299 if (!fhdr) 300 goto out_err; 301 302 if (extable_len) 303 fp->aux->extable = (void *)fimage + FUNCTION_DESCR_SIZE + proglen + fixup_len; 304 305 skip_init_ctx: 306 code_base = (u32 *)(image + FUNCTION_DESCR_SIZE); 307 fcode_base = (u32 *)(fimage + FUNCTION_DESCR_SIZE); 308 309 /* Code generation passes 1-2 */ 310 for (pass = 1; pass < 3; pass++) { 311 /* Now build the prologue, body code & epilogue for real. */ 312 cgctx.idx = 0; 313 cgctx.alt_exit_addr = 0; 314 bpf_jit_build_prologue(code_base, &cgctx); 315 if (bpf_jit_build_body(fp, code_base, fcode_base, &cgctx, addrs, pass, 316 extra_pass)) { 317 bpf_arch_text_copy(&fhdr->size, &hdr->size, sizeof(hdr->size)); 318 bpf_jit_binary_pack_free(fhdr, hdr); 319 goto out_err; 320 } 321 bpf_jit_build_epilogue(code_base, &cgctx); 322 323 if (bpf_jit_enable > 1) 324 pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass, 325 proglen - (cgctx.idx * 4), cgctx.seen); 326 } 327 328 if (bpf_jit_enable > 1) 329 /* 330 * Note that we output the base address of the code_base 331 * rather than image, since opcodes are in code_base. 332 */ 333 bpf_jit_dump(flen, proglen, pass, code_base); 334 335 #ifdef CONFIG_PPC64_ELF_ABI_V1 336 /* Function descriptor nastiness: Address + TOC */ 337 ((u64 *)image)[0] = (u64)fcode_base; 338 ((u64 *)image)[1] = local_paca->kernel_toc; 339 #endif 340 341 if (!fp->is_func || extra_pass) { 342 if (bpf_jit_binary_pack_finalize(fhdr, hdr)) 343 goto out_err; 344 } 345 346 fp->bpf_func = (void *)fimage; 347 fp->jited = 1; 348 fp->jited_len = cgctx.idx * 4 + FUNCTION_DESCR_SIZE; 349 350 if (!fp->is_func || extra_pass) { 351 bpf_prog_fill_jited_linfo(fp, addrs); 352 /* 353 * On ABI V1, executable code starts after the function 354 * descriptor, so adjust base accordingly. 355 */ 356 bpf_prog_update_insn_ptrs(fp, addrs, 357 (void *)fimage + FUNCTION_DESCR_SIZE); 358 359 out_addrs: 360 if (!image && priv_stack_ptr) { 361 fp->aux->priv_stack_ptr = NULL; 362 free_percpu(priv_stack_ptr); 363 } 364 out_priv_stack: 365 kfree(addrs); 366 kfree(jit_data); 367 fp->aux->jit_data = NULL; 368 } else { 369 jit_data->addrs = addrs; 370 jit_data->ctx = cgctx; 371 jit_data->proglen = proglen; 372 jit_data->fimage = fimage; 373 jit_data->fhdr = fhdr; 374 jit_data->hdr = hdr; 375 } 376 377 return fp; 378 379 out_err: 380 if (extra_pass) { 381 fp->bpf_func = NULL; 382 fp->jited = 0; 383 fp->jited_len = 0; 384 } 385 goto out_addrs; 386 } 387 388 /* 389 * The caller should check for (BPF_MODE(code) == BPF_PROBE_MEM) before calling 390 * this function, as this only applies to BPF_PROBE_MEM, for now. 391 */ 392 int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass, 393 struct codegen_context *ctx, int insn_idx, int jmp_off, 394 int dst_reg, u32 code) 395 { 396 off_t offset; 397 unsigned long pc; 398 struct exception_table_entry *ex, *ex_entry; 399 u32 *fixup; 400 401 /* Populate extable entries only in the last pass */ 402 if (pass != 2) 403 return 0; 404 405 if (!fp->aux->extable || 406 WARN_ON_ONCE(ctx->exentry_idx >= fp->aux->num_exentries)) 407 return -EINVAL; 408 409 /* 410 * Program is first written to image before copying to the 411 * final location (fimage). Accordingly, update in the image first. 412 * As all offsets used are relative, copying as is to the 413 * final location should be alright. 414 */ 415 pc = (unsigned long)&image[insn_idx]; 416 ex = (void *)fp->aux->extable - (void *)fimage + (void *)image; 417 418 fixup = (void *)ex - 419 (fp->aux->num_exentries * BPF_FIXUP_LEN * 4) + 420 (ctx->exentry_idx * BPF_FIXUP_LEN * 4); 421 422 fixup[0] = PPC_RAW_LI(dst_reg, 0); 423 if (BPF_CLASS(code) == BPF_ST || BPF_CLASS(code) == BPF_STX) 424 fixup[0] = PPC_RAW_NOP(); 425 426 if (IS_ENABLED(CONFIG_PPC32)) 427 fixup[1] = PPC_RAW_LI(dst_reg - 1, 0); /* clear higher 32-bit register too */ 428 429 fixup[BPF_FIXUP_LEN - 1] = 430 PPC_RAW_BRANCH((long)(pc + jmp_off) - (long)&fixup[BPF_FIXUP_LEN - 1]); 431 432 ex_entry = &ex[ctx->exentry_idx]; 433 434 offset = pc - (long)&ex_entry->insn; 435 if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN)) 436 return -ERANGE; 437 ex_entry->insn = offset; 438 439 offset = (long)fixup - (long)&ex_entry->fixup; 440 if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN)) 441 return -ERANGE; 442 ex_entry->fixup = offset; 443 444 ctx->exentry_idx++; 445 return 0; 446 } 447 448 void *bpf_arch_text_copy(void *dst, void *src, size_t len) 449 { 450 int err; 451 452 if (WARN_ON_ONCE(core_kernel_text((unsigned long)dst))) 453 return ERR_PTR(-EINVAL); 454 455 mutex_lock(&text_mutex); 456 err = patch_instructions(dst, src, len, false); 457 mutex_unlock(&text_mutex); 458 459 return err ? ERR_PTR(err) : dst; 460 } 461 462 int bpf_arch_text_invalidate(void *dst, size_t len) 463 { 464 u32 insn = BREAKPOINT_INSTRUCTION; 465 int ret; 466 467 if (WARN_ON_ONCE(core_kernel_text((unsigned long)dst))) 468 return -EINVAL; 469 470 mutex_lock(&text_mutex); 471 ret = patch_instructions(dst, &insn, len, true); 472 mutex_unlock(&text_mutex); 473 474 return ret; 475 } 476 477 void bpf_jit_free(struct bpf_prog *fp) 478 { 479 if (fp->jited) { 480 struct powerpc_jit_data *jit_data = fp->aux->jit_data; 481 struct bpf_binary_header *hdr; 482 void __percpu *priv_stack_ptr; 483 int priv_stack_alloc_size; 484 485 /* 486 * If we fail the final pass of JIT (from jit_subprogs), 487 * the program may not be finalized yet. Call finalize here 488 * before freeing it. 489 */ 490 if (jit_data) { 491 bpf_jit_binary_pack_finalize(jit_data->fhdr, jit_data->hdr); 492 kvfree(jit_data->addrs); 493 kfree(jit_data); 494 } 495 hdr = bpf_jit_binary_pack_hdr(fp); 496 bpf_jit_binary_pack_free(hdr, NULL); 497 priv_stack_ptr = fp->aux->priv_stack_ptr; 498 if (priv_stack_ptr) { 499 priv_stack_alloc_size = round_up(fp->aux->stack_depth, 16) + 500 2 * PRIV_STACK_GUARD_SZ; 501 priv_stack_check_guard(priv_stack_ptr, priv_stack_alloc_size, fp); 502 free_percpu(priv_stack_ptr); 503 } 504 WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(fp)); 505 } 506 507 bpf_prog_unlock_free(fp); 508 } 509 510 bool bpf_jit_supports_exceptions(void) 511 { 512 return IS_ENABLED(CONFIG_PPC64); 513 } 514 515 bool bpf_jit_supports_subprog_tailcalls(void) 516 { 517 return IS_ENABLED(CONFIG_PPC64); 518 } 519 520 bool bpf_jit_supports_timed_may_goto(void) 521 { 522 return IS_ENABLED(CONFIG_PPC64); 523 } 524 525 bool bpf_jit_supports_kfunc_call(void) 526 { 527 return IS_ENABLED(CONFIG_PPC64); 528 } 529 530 bool bpf_jit_supports_private_stack(void) 531 { 532 return IS_ENABLED(CONFIG_PPC64); 533 } 534 535 bool bpf_jit_supports_fsession(void) 536 { 537 /* 538 * TODO: Remove after validating support 539 * for fsession and trampoline on ppc32. 540 */ 541 if (IS_ENABLED(CONFIG_PPC32)) 542 return -EOPNOTSUPP; 543 return true; 544 } 545 546 bool bpf_jit_supports_arena(void) 547 { 548 return IS_ENABLED(CONFIG_PPC64); 549 } 550 551 bool bpf_jit_supports_far_kfunc_call(void) 552 { 553 return IS_ENABLED(CONFIG_PPC64); 554 } 555 556 bool bpf_jit_supports_insn(struct bpf_insn *insn, bool in_arena) 557 { 558 if (!in_arena) 559 return true; 560 switch (insn->code) { 561 case BPF_STX | BPF_ATOMIC | BPF_H: 562 case BPF_STX | BPF_ATOMIC | BPF_B: 563 case BPF_STX | BPF_ATOMIC | BPF_W: 564 case BPF_STX | BPF_ATOMIC | BPF_DW: 565 if (bpf_atomic_is_load_store(insn)) 566 return false; 567 return IS_ENABLED(CONFIG_PPC64); 568 } 569 return true; 570 } 571 572 bool bpf_jit_supports_percpu_insn(void) 573 { 574 return IS_ENABLED(CONFIG_PPC64); 575 } 576 577 bool bpf_jit_inlines_helper_call(s32 imm) 578 { 579 switch (imm) { 580 case BPF_FUNC_get_smp_processor_id: 581 case BPF_FUNC_get_current_task: 582 case BPF_FUNC_get_current_task_btf: 583 return true; 584 default: 585 return false; 586 } 587 } 588 589 void *arch_alloc_bpf_trampoline(unsigned int size) 590 { 591 return bpf_prog_pack_alloc(size, bpf_jit_fill_ill_insns); 592 } 593 594 void arch_free_bpf_trampoline(void *image, unsigned int size) 595 { 596 bpf_prog_pack_free(image, size); 597 } 598 599 int arch_protect_bpf_trampoline(void *image, unsigned int size) 600 { 601 return 0; 602 } 603 604 static int invoke_bpf_prog(u32 *image, u32 *ro_image, struct codegen_context *ctx, 605 struct bpf_tramp_node *n, int regs_off, int retval_off, 606 int run_ctx_off, bool save_ret) 607 { 608 struct bpf_prog *p = n->link->prog; 609 ppc_inst_t branch_insn; 610 u32 jmp_idx; 611 int ret = 0; 612 613 /* Save cookie */ 614 if (IS_ENABLED(CONFIG_PPC64)) { 615 PPC_LI64(_R3, n->cookie); 616 EMIT(PPC_RAW_STD(_R3, _R1, run_ctx_off + offsetof(struct bpf_tramp_run_ctx, 617 bpf_cookie))); 618 } else { 619 PPC_LI32(_R3, n->cookie >> 32); 620 PPC_LI32(_R4, n->cookie); 621 EMIT(PPC_RAW_STW(_R3, _R1, 622 run_ctx_off + offsetof(struct bpf_tramp_run_ctx, bpf_cookie))); 623 EMIT(PPC_RAW_STW(_R4, _R1, 624 run_ctx_off + offsetof(struct bpf_tramp_run_ctx, bpf_cookie) + 4)); 625 } 626 627 /* __bpf_prog_enter(p, &bpf_tramp_run_ctx) */ 628 PPC_LI_ADDR(_R3, p); 629 EMIT(PPC_RAW_MR(_R25, _R3)); 630 EMIT(PPC_RAW_ADDI(_R4, _R1, run_ctx_off)); 631 ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, 632 (unsigned long)bpf_trampoline_enter(p)); 633 if (ret) 634 return ret; 635 636 /* Remember prog start time returned by __bpf_prog_enter */ 637 EMIT(PPC_RAW_MR(_R26, _R3)); 638 639 /* 640 * if (__bpf_prog_enter(p) == 0) 641 * goto skip_exec_of_prog; 642 * 643 * Emit a nop to be later patched with conditional branch, once offset is known 644 */ 645 EMIT(PPC_RAW_CMPLI(_R3, 0)); 646 jmp_idx = ctx->idx; 647 EMIT(PPC_RAW_NOP()); 648 649 /* p->bpf_func(ctx) */ 650 EMIT(PPC_RAW_ADDI(_R3, _R1, regs_off)); 651 if (!p->jited) 652 PPC_LI_ADDR(_R4, (unsigned long)p->insnsi); 653 /* Account for max possible instructions during dummy pass for size calculation */ 654 if (image && !create_branch(&branch_insn, (u32 *)&ro_image[ctx->idx], 655 (unsigned long)p->bpf_func, 656 BRANCH_SET_LINK)) { 657 image[ctx->idx] = ppc_inst_val(branch_insn); 658 ctx->idx++; 659 } else { 660 EMIT(PPC_RAW_LL(_R12, _R25, offsetof(struct bpf_prog, bpf_func))); 661 EMIT(PPC_RAW_MTCTR(_R12)); 662 EMIT(PPC_RAW_BCTRL()); 663 } 664 665 if (save_ret) 666 EMIT(PPC_RAW_STL(_R3, _R1, retval_off)); 667 668 /* Fix up branch */ 669 if (image) { 670 if (create_cond_branch(&branch_insn, &image[jmp_idx], 671 (unsigned long)&image[ctx->idx], COND_EQ << 16)) 672 return -EINVAL; 673 image[jmp_idx] = ppc_inst_val(branch_insn); 674 } 675 676 /* __bpf_prog_exit(p, start_time, &bpf_tramp_run_ctx) */ 677 EMIT(PPC_RAW_MR(_R3, _R25)); 678 EMIT(PPC_RAW_MR(_R4, _R26)); 679 EMIT(PPC_RAW_ADDI(_R5, _R1, run_ctx_off)); 680 ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, 681 (unsigned long)bpf_trampoline_exit(p)); 682 683 return ret; 684 } 685 686 static int invoke_bpf_mod_ret(u32 *image, u32 *ro_image, struct codegen_context *ctx, 687 struct bpf_tramp_nodes *tn, int regs_off, int retval_off, 688 int run_ctx_off, u32 *branches) 689 { 690 int i; 691 692 /* 693 * The first fmod_ret program will receive a garbage return value. 694 * Set this to 0 to avoid confusing the program. 695 */ 696 EMIT(PPC_RAW_LI(_R3, 0)); 697 EMIT(PPC_RAW_STL(_R3, _R1, retval_off)); 698 for (i = 0; i < tn->nr_nodes; i++) { 699 if (invoke_bpf_prog(image, ro_image, ctx, tn->nodes[i], regs_off, retval_off, 700 run_ctx_off, true)) 701 return -EINVAL; 702 703 /* 704 * mod_ret prog stored return value after prog ctx. Emit: 705 * if (*(u64 *)(ret_val) != 0) 706 * goto do_fexit; 707 */ 708 EMIT(PPC_RAW_LL(_R3, _R1, retval_off)); 709 EMIT(PPC_RAW_CMPLI(_R3, 0)); 710 711 /* 712 * Save the location of the branch and generate a nop, which is 713 * replaced with a conditional jump once do_fexit (i.e. the 714 * start of the fexit invocation) is finalized. 715 */ 716 branches[i] = ctx->idx; 717 EMIT(PPC_RAW_NOP()); 718 } 719 720 return 0; 721 } 722 723 /* 724 * Refer __arch_prepare_bpf_trampoline() for stack component details. 725 * 726 * The tailcall count/reference is present in caller's stack frame. The 727 * tail_call_info is saved at the same offset on the trampoline frame 728 * for the traced function (BPF subprog/callee) to fetch it. 729 */ 730 static void bpf_trampoline_setup_tail_call_info(u32 *image, struct codegen_context *ctx, 731 int bpf_frame_size, int r4_off) 732 { 733 if (IS_ENABLED(CONFIG_PPC64)) { 734 EMIT(PPC_RAW_LD(_R4, _R1, bpf_frame_size)); 735 /* Refer to trampoline's Generated stack layout */ 736 EMIT(PPC_RAW_LD(_R3, _R4, -BPF_PPC_TAILCALL)); 737 738 /* 739 * Setting the tail_call_info in trampoline's frame 740 * depending on if previous frame had value or reference. 741 */ 742 EMIT(PPC_RAW_CMPLWI(_R3, MAX_TAIL_CALL_CNT)); 743 PPC_BCC_CONST_SHORT(COND_GT, 8); 744 EMIT(PPC_RAW_ADDI(_R3, _R4, -BPF_PPC_TAILCALL)); 745 746 /* 747 * Trampoline's tail_call_info is at the same offset, as that of 748 * any bpf program, with reference to previous frame. Update the 749 * address of main's tail_call_info in trampoline frame. 750 */ 751 EMIT(PPC_RAW_STL(_R3, _R1, bpf_frame_size - BPF_PPC_TAILCALL)); 752 } else { 753 /* See bpf_jit_stack_offsetof() and BPF_PPC_TC */ 754 EMIT(PPC_RAW_LL(_R4, _R1, r4_off)); 755 } 756 } 757 758 static void bpf_trampoline_restore_tail_call_cnt(u32 *image, struct codegen_context *ctx, 759 int bpf_frame_size, int r4_off) 760 { 761 if (IS_ENABLED(CONFIG_PPC32)) { 762 /* 763 * Restore tailcall for 32-bit powerpc 764 * See bpf_jit_stack_offsetof() and BPF_PPC_TC 765 */ 766 EMIT(PPC_RAW_STL(_R4, _R1, r4_off)); 767 } 768 } 769 770 static void bpf_trampoline_save_args(u32 *image, struct codegen_context *ctx, 771 int bpf_frame_size, int nr_regs, int regs_off) 772 { 773 int param_save_area_offset; 774 775 param_save_area_offset = bpf_frame_size; 776 param_save_area_offset += STACK_FRAME_MIN_SIZE; /* param save area is past frame header */ 777 778 for (int i = 0; i < nr_regs; i++) { 779 if (i < 8) { 780 EMIT(PPC_RAW_STL(_R3 + i, _R1, regs_off + i * SZL)); 781 } else { 782 EMIT(PPC_RAW_LL(_R3, _R1, param_save_area_offset + i * SZL)); 783 EMIT(PPC_RAW_STL(_R3, _R1, regs_off + i * SZL)); 784 } 785 } 786 } 787 788 /* Used when restoring just the register parameters when returning back */ 789 static void bpf_trampoline_restore_args_regs(u32 *image, struct codegen_context *ctx, 790 int nr_regs, int regs_off) 791 { 792 for (int i = 0; i < nr_regs && i < 8; i++) 793 EMIT(PPC_RAW_LL(_R3 + i, _R1, regs_off + i * SZL)); 794 } 795 796 /* Used when we call into the traced function. Replicate parameter save area */ 797 static void bpf_trampoline_restore_args_stack(u32 *image, struct codegen_context *ctx, 798 int bpf_frame_size, int nr_regs, int regs_off) 799 { 800 int param_save_area_offset; 801 802 param_save_area_offset = bpf_frame_size; 803 param_save_area_offset += STACK_FRAME_MIN_SIZE; /* param save area is past frame header */ 804 805 for (int i = 8; i < nr_regs; i++) { 806 EMIT(PPC_RAW_LL(_R3, _R1, param_save_area_offset + i * SZL)); 807 EMIT(PPC_RAW_STL(_R3, _R1, STACK_FRAME_MIN_SIZE + i * SZL)); 808 } 809 bpf_trampoline_restore_args_regs(image, ctx, nr_regs, regs_off); 810 } 811 812 static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_image, 813 void *rw_image_end, void *ro_image, 814 const struct btf_func_model *m, u32 flags, 815 struct bpf_tramp_nodes *tnodes, 816 void *func_addr) 817 { 818 int regs_off, func_meta_off, ip_off, run_ctx_off, retval_off; 819 int nvr_off, alt_lr_off, r4_off = 0; 820 struct bpf_tramp_nodes *fmod_ret = &tnodes[BPF_TRAMP_MODIFY_RETURN]; 821 struct bpf_tramp_nodes *fentry = &tnodes[BPF_TRAMP_FENTRY]; 822 struct bpf_tramp_nodes *fexit = &tnodes[BPF_TRAMP_FEXIT]; 823 int i, ret, nr_regs, retaddr_off, bpf_frame_size = 0; 824 struct codegen_context codegen_ctx, *ctx; 825 int cookie_off, cookie_cnt, cookie_ctx_off; 826 int fsession_cnt = bpf_fsession_cnt(tnodes); 827 u64 func_meta; 828 u32 *image = (u32 *)rw_image; 829 ppc_inst_t branch_insn; 830 u32 *branches = NULL; 831 bool save_ret; 832 833 if (IS_ENABLED(CONFIG_PPC32)) 834 return -EOPNOTSUPP; 835 836 nr_regs = m->nr_args; 837 /* Extra registers for struct arguments */ 838 for (i = 0; i < m->nr_args; i++) 839 if (m->arg_size[i] > SZL) 840 nr_regs += round_up(m->arg_size[i], SZL) / SZL - 1; 841 842 if (nr_regs > MAX_BPF_FUNC_ARGS) 843 return -EOPNOTSUPP; 844 845 ctx = &codegen_ctx; 846 memset(ctx, 0, sizeof(*ctx)); 847 848 /* 849 * Generated stack layout: 850 * 851 * func prev back chain [ back chain ] 852 * [ tail_call_info ] optional - 64-bit powerpc 853 * [ padding ] align stack frame 854 * r4_off [ r4 (tailcallcnt) ] optional - 32-bit powerpc 855 * alt_lr_off [ real lr (ool stub)] optional - actual lr 856 * retaddr_off [ return address ] 857 * [ r26 ] 858 * nvr_off [ r25 ] nvr save area 859 * retval_off [ return value ] 860 * [ reg argN ] 861 * [ ... ] 862 * regs_off [ reg_arg1 ] prog_ctx 863 * func_meta_off [ args count ] ((u64 *)prog_ctx)[-1] 864 * ip_off [ traced function ] ((u64 *)prog_ctx)[-2] 865 * [ stack cookieN ] 866 * [ ... ] 867 * cookie_off [ stack cookie1 ] 868 * run_ctx_off [ bpf_tramp_run_ctx ] 869 * [ reg argN ] 870 * [ ... ] 871 * param_save_area [ reg_arg1 ] min 8 doublewords, per ABI 872 * [ TOC save (64-bit) ] -- 873 * [ LR save (64-bit) ] | header 874 * [ LR save (32-bit) ] | 875 * bpf trampoline frame [ back chain 2 ] -- 876 * 877 */ 878 879 /* Minimum stack frame header */ 880 bpf_frame_size = STACK_FRAME_MIN_SIZE; 881 882 /* 883 * Room for parameter save area. 884 * 885 * As per the ABI, this is required if we call into the traced 886 * function (BPF_TRAMP_F_CALL_ORIG): 887 * - if the function takes more than 8 arguments for the rest to spill onto the stack 888 * - or, if the function has variadic arguments 889 * - or, if this functions's prototype was not available to the caller 890 * 891 * Reserve space for at least 8 registers for now. This can be optimized later. 892 */ 893 bpf_frame_size += (nr_regs > 8 ? nr_regs : 8) * SZL; 894 895 /* Room for struct bpf_tramp_run_ctx */ 896 run_ctx_off = bpf_frame_size; 897 bpf_frame_size += round_up(sizeof(struct bpf_tramp_run_ctx), SZL); 898 899 /* room for session cookies */ 900 cookie_off = bpf_frame_size; 901 cookie_cnt = bpf_fsession_cookie_cnt(tnodes); 902 bpf_frame_size += cookie_cnt * 8; 903 904 /* Room for IP address argument */ 905 ip_off = bpf_frame_size; 906 if (flags & BPF_TRAMP_F_IP_ARG) 907 bpf_frame_size += SZL; 908 909 /* Room for function metadata, arg regs count */ 910 func_meta_off = bpf_frame_size; 911 bpf_frame_size += SZL; 912 913 /* Room for arg regs */ 914 regs_off = bpf_frame_size; 915 bpf_frame_size += nr_regs * SZL; 916 917 /* Room for return value of func_addr or fentry prog */ 918 retval_off = bpf_frame_size; 919 save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET); 920 if (save_ret) 921 bpf_frame_size += SZL; 922 923 /* Room for nvr save area */ 924 nvr_off = bpf_frame_size; 925 bpf_frame_size += 2 * SZL; 926 927 /* Save area for return address */ 928 retaddr_off = bpf_frame_size; 929 bpf_frame_size += SZL; 930 931 /* Optional save area for actual LR in case of ool ftrace */ 932 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) { 933 alt_lr_off = bpf_frame_size; 934 bpf_frame_size += SZL; 935 } 936 937 if (IS_ENABLED(CONFIG_PPC32)) { 938 if (nr_regs < 2) { 939 r4_off = bpf_frame_size; 940 bpf_frame_size += SZL; 941 } else { 942 r4_off = regs_off + SZL; 943 } 944 } 945 946 /* 947 * Save tailcall count pointer at the same offset on the 948 * stack where subprogs expect it 949 */ 950 if ((flags & BPF_TRAMP_F_CALL_ORIG) && 951 (flags & BPF_TRAMP_F_TAIL_CALL_CTX)) 952 bpf_frame_size += BPF_PPC_TAILCALL; 953 954 /* Padding to align stack frame, if any */ 955 bpf_frame_size = round_up(bpf_frame_size, SZL * 2); 956 957 /* Store original return value */ 958 EMIT(PPC_RAW_STL(_R0, _R1, PPC_LR_STKOFF)); 959 960 /* Create our stack frame */ 961 EMIT(PPC_RAW_STLU(_R1, _R1, -bpf_frame_size)); 962 963 /* 64-bit: Save TOC and load kernel TOC */ 964 if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) { 965 EMIT(PPC_RAW_STD(_R2, _R1, 24)); 966 PPC64_LOAD_PACA(); 967 } 968 969 /* 32-bit: save tail call count in r4 */ 970 if (IS_ENABLED(CONFIG_PPC32) && nr_regs < 2) 971 EMIT(PPC_RAW_STL(_R4, _R1, r4_off)); 972 973 bpf_trampoline_save_args(image, ctx, bpf_frame_size, nr_regs, regs_off); 974 975 /* Save our LR/return address */ 976 EMIT(PPC_RAW_MFLR(_R3)); 977 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) 978 EMIT(PPC_RAW_STL(_R3, _R1, alt_lr_off)); 979 else 980 EMIT(PPC_RAW_STL(_R3, _R1, retaddr_off)); 981 982 /* 983 * Derive IP address of the traced function. 984 * In case of CONFIG_PPC_FTRACE_OUT_OF_LINE or BPF program, LR points to the instruction 985 * after the 'bl' instruction in the OOL stub. Refer to ftrace_init_ool_stub() and 986 * bpf_arch_text_poke() for OOL stub of kernel functions and bpf programs respectively. 987 * Relevant stub sequence: 988 * 989 * bl <tramp> 990 * LR (R3) => mtlr r0 991 * b <func_addr+4> 992 * 993 * Recover kernel function/bpf program address from the unconditional 994 * branch instruction at the end of OOL stub. 995 */ 996 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE) || flags & BPF_TRAMP_F_IP_ARG) { 997 EMIT(PPC_RAW_LWZ(_R4, _R3, 4)); 998 EMIT(PPC_RAW_SLWI(_R4, _R4, 6)); 999 EMIT(PPC_RAW_SRAWI(_R4, _R4, 6)); 1000 EMIT(PPC_RAW_ADD(_R3, _R3, _R4)); 1001 } 1002 1003 if (flags & BPF_TRAMP_F_IP_ARG) 1004 EMIT(PPC_RAW_STL(_R3, _R1, ip_off)); 1005 1006 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) { 1007 /* Fake our LR for BPF_TRAMP_F_CALL_ORIG case */ 1008 EMIT(PPC_RAW_ADDI(_R3, _R3, 4)); 1009 EMIT(PPC_RAW_STL(_R3, _R1, retaddr_off)); 1010 } 1011 1012 /* Save function arg regs count -- see bpf_get_func_arg_cnt() */ 1013 func_meta = nr_regs; 1014 store_func_meta(image, ctx, func_meta, func_meta_off); 1015 1016 /* Save nv regs */ 1017 EMIT(PPC_RAW_STL(_R25, _R1, nvr_off)); 1018 EMIT(PPC_RAW_STL(_R26, _R1, nvr_off + SZL)); 1019 1020 if (flags & BPF_TRAMP_F_CALL_ORIG) { 1021 PPC_LI_ADDR(_R3, (unsigned long)im); 1022 ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, 1023 (unsigned long)__bpf_tramp_enter); 1024 if (ret) 1025 return ret; 1026 } 1027 1028 if (fsession_cnt) { 1029 /* 1030 * Clear all the session cookies' values 1031 * Clear the return value to make sure fentry always get 0 1032 */ 1033 prepare_for_fsession_fentry(image, ctx, cookie_cnt, cookie_off, retval_off); 1034 } 1035 1036 cookie_ctx_off = (regs_off - cookie_off) / 8; 1037 1038 for (i = 0; i < fentry->nr_nodes; i++) { 1039 if (bpf_prog_calls_session_cookie(fentry->nodes[i])) { 1040 u64 meta = func_meta | (cookie_ctx_off << BPF_TRAMP_COOKIE_INDEX_SHIFT); 1041 1042 store_func_meta(image, ctx, meta, func_meta_off); 1043 cookie_ctx_off--; 1044 } 1045 1046 if (invoke_bpf_prog(image, ro_image, ctx, fentry->nodes[i], regs_off, retval_off, 1047 run_ctx_off, flags & BPF_TRAMP_F_RET_FENTRY_RET)) 1048 return -EINVAL; 1049 } 1050 1051 if (fmod_ret->nr_nodes) { 1052 branches = kcalloc(fmod_ret->nr_nodes, sizeof(u32), GFP_KERNEL); 1053 if (!branches) 1054 return -ENOMEM; 1055 1056 if (invoke_bpf_mod_ret(image, ro_image, ctx, fmod_ret, regs_off, retval_off, 1057 run_ctx_off, branches)) { 1058 ret = -EINVAL; 1059 goto cleanup; 1060 } 1061 } 1062 1063 /* Call the traced function */ 1064 if (flags & BPF_TRAMP_F_CALL_ORIG) { 1065 /* 1066 * retaddr on trampoline stack points to the correct point in the original function 1067 * with both PPC_FTRACE_OUT_OF_LINE as well as with traditional ftrace instruction 1068 * sequence 1069 */ 1070 EMIT(PPC_RAW_LL(_R3, _R1, retaddr_off)); 1071 EMIT(PPC_RAW_MTCTR(_R3)); 1072 1073 /* Replicate tail_call_cnt before calling the original BPF prog */ 1074 if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) 1075 bpf_trampoline_setup_tail_call_info(image, ctx, bpf_frame_size, r4_off); 1076 1077 /* Restore args */ 1078 bpf_trampoline_restore_args_stack(image, ctx, bpf_frame_size, nr_regs, regs_off); 1079 1080 /* Restore TOC for 64-bit */ 1081 if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) 1082 EMIT(PPC_RAW_LD(_R2, _R1, 24)); 1083 EMIT(PPC_RAW_BCTRL()); 1084 if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) 1085 PPC64_LOAD_PACA(); 1086 1087 /* Store return value for bpf prog to access */ 1088 EMIT(PPC_RAW_STL(_R3, _R1, retval_off)); 1089 1090 /* Restore updated tail_call_cnt */ 1091 if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) 1092 bpf_trampoline_restore_tail_call_cnt(image, ctx, bpf_frame_size, r4_off); 1093 1094 /* Reserve space to patch branch instruction to skip fexit progs */ 1095 if (ro_image) /* image is NULL for dummy pass */ 1096 im->ip_after_call = &((u32 *)ro_image)[ctx->idx]; 1097 EMIT(PPC_RAW_NOP()); 1098 } 1099 1100 /* Update branches saved in invoke_bpf_mod_ret with address of do_fexit */ 1101 for (i = 0; i < fmod_ret->nr_nodes && image; i++) { 1102 if (create_cond_branch(&branch_insn, &image[branches[i]], 1103 (unsigned long)&image[ctx->idx], COND_NE << 16)) { 1104 ret = -EINVAL; 1105 goto cleanup; 1106 } 1107 1108 image[branches[i]] = ppc_inst_val(branch_insn); 1109 } 1110 1111 /* set the "is_return" flag for fsession */ 1112 func_meta |= (1ULL << BPF_TRAMP_IS_RETURN_SHIFT); 1113 if (fsession_cnt) 1114 store_func_meta(image, ctx, func_meta, func_meta_off); 1115 1116 cookie_ctx_off = (regs_off - cookie_off) / 8; 1117 1118 for (i = 0; i < fexit->nr_nodes; i++) { 1119 if (bpf_prog_calls_session_cookie(fexit->nodes[i])) { 1120 u64 meta = func_meta | (cookie_ctx_off << BPF_TRAMP_COOKIE_INDEX_SHIFT); 1121 1122 store_func_meta(image, ctx, meta, func_meta_off); 1123 cookie_ctx_off--; 1124 } 1125 1126 if (invoke_bpf_prog(image, ro_image, ctx, fexit->nodes[i], regs_off, retval_off, 1127 run_ctx_off, false)) { 1128 ret = -EINVAL; 1129 goto cleanup; 1130 } 1131 } 1132 1133 if (flags & BPF_TRAMP_F_CALL_ORIG) { 1134 if (ro_image) /* image is NULL for dummy pass */ 1135 im->ip_epilogue = &((u32 *)ro_image)[ctx->idx]; 1136 PPC_LI_ADDR(_R3, im); 1137 ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, 1138 (unsigned long)__bpf_tramp_exit); 1139 if (ret) 1140 goto cleanup; 1141 } 1142 1143 if (flags & BPF_TRAMP_F_RESTORE_REGS) 1144 bpf_trampoline_restore_args_regs(image, ctx, nr_regs, regs_off); 1145 1146 /* Restore return value of func_addr or fentry prog */ 1147 if (save_ret) 1148 EMIT(PPC_RAW_LL(_R3, _R1, retval_off)); 1149 1150 /* Restore nv regs */ 1151 EMIT(PPC_RAW_LL(_R26, _R1, nvr_off + SZL)); 1152 EMIT(PPC_RAW_LL(_R25, _R1, nvr_off)); 1153 1154 /* Epilogue */ 1155 if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) 1156 EMIT(PPC_RAW_LD(_R2, _R1, 24)); 1157 if (flags & BPF_TRAMP_F_SKIP_FRAME) { 1158 /* Skip the traced function and return to parent */ 1159 EMIT(PPC_RAW_ADDI(_R1, _R1, bpf_frame_size)); 1160 EMIT(PPC_RAW_LL(_R0, _R1, PPC_LR_STKOFF)); 1161 EMIT(PPC_RAW_MTLR(_R0)); 1162 EMIT(PPC_RAW_BLR()); 1163 } else { 1164 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) { 1165 EMIT(PPC_RAW_LL(_R0, _R1, alt_lr_off)); 1166 EMIT(PPC_RAW_MTLR(_R0)); 1167 EMIT(PPC_RAW_ADDI(_R1, _R1, bpf_frame_size)); 1168 EMIT(PPC_RAW_LL(_R0, _R1, PPC_LR_STKOFF)); 1169 EMIT(PPC_RAW_BLR()); 1170 } else { 1171 EMIT(PPC_RAW_LL(_R0, _R1, retaddr_off)); 1172 EMIT(PPC_RAW_MTCTR(_R0)); 1173 EMIT(PPC_RAW_ADDI(_R1, _R1, bpf_frame_size)); 1174 EMIT(PPC_RAW_LL(_R0, _R1, PPC_LR_STKOFF)); 1175 EMIT(PPC_RAW_MTLR(_R0)); 1176 EMIT(PPC_RAW_BCTR()); 1177 } 1178 } 1179 1180 /* Make sure the trampoline generation logic doesn't overflow */ 1181 if (image && WARN_ON_ONCE(&image[ctx->idx] > (u32 *)rw_image_end - BPF_INSN_SAFETY)) { 1182 ret = -EFAULT; 1183 goto cleanup; 1184 } 1185 ret = ctx->idx * 4 + BPF_INSN_SAFETY * 4; 1186 1187 cleanup: 1188 kfree(branches); 1189 return ret; 1190 } 1191 1192 int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, 1193 struct bpf_tramp_nodes *tnodes, void *func_addr) 1194 { 1195 struct bpf_tramp_image im; 1196 int ret; 1197 1198 ret = __arch_prepare_bpf_trampoline(&im, NULL, NULL, NULL, m, flags, tnodes, func_addr); 1199 return ret; 1200 } 1201 1202 int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, 1203 const struct btf_func_model *m, u32 flags, 1204 struct bpf_tramp_nodes *tnodes, 1205 void *func_addr) 1206 { 1207 u32 size = image_end - image; 1208 void *rw_image, *tmp; 1209 int ret; 1210 1211 /* 1212 * rw_image doesn't need to be in module memory range, so we can 1213 * use kvmalloc. 1214 */ 1215 rw_image = kvmalloc(size, GFP_KERNEL); 1216 if (!rw_image) 1217 return -ENOMEM; 1218 1219 ret = __arch_prepare_bpf_trampoline(im, rw_image, rw_image + size, image, m, 1220 flags, tnodes, func_addr); 1221 if (ret < 0) 1222 goto out; 1223 1224 if (bpf_jit_enable > 1) 1225 bpf_jit_dump(1, ret - BPF_INSN_SAFETY * 4, 1, rw_image); 1226 1227 tmp = bpf_arch_text_copy(image, rw_image, size); 1228 if (IS_ERR(tmp)) 1229 ret = PTR_ERR(tmp); 1230 1231 out: 1232 kvfree(rw_image); 1233 return ret; 1234 } 1235 1236 static int bpf_modify_inst(void *ip, ppc_inst_t old_inst, ppc_inst_t new_inst) 1237 { 1238 ppc_inst_t org_inst; 1239 1240 if (copy_inst_from_kernel_nofault(&org_inst, ip)) { 1241 pr_err("0x%lx: fetching instruction failed\n", (unsigned long)ip); 1242 return -EFAULT; 1243 } 1244 1245 if (!ppc_inst_equal(org_inst, old_inst)) { 1246 pr_err("0x%lx: expected (%08lx) != found (%08lx)\n", 1247 (unsigned long)ip, ppc_inst_as_ulong(old_inst), ppc_inst_as_ulong(org_inst)); 1248 return -EINVAL; 1249 } 1250 1251 if (ppc_inst_equal(old_inst, new_inst)) 1252 return 0; 1253 1254 return patch_instruction(ip, new_inst); 1255 } 1256 1257 static void do_isync(void *info __maybe_unused) 1258 { 1259 isync(); 1260 } 1261 1262 /* 1263 * A 3-step process for bpf prog entry: 1264 * 1. At bpf prog entry, a single nop/b: 1265 * bpf_func: 1266 * [nop|b] ool_stub 1267 * 2. Out-of-line stub: 1268 * ool_stub: 1269 * mflr r0 1270 * [b|bl] <bpf_prog>/<long_branch_stub> 1271 * mtlr r0 // CONFIG_PPC_FTRACE_OUT_OF_LINE only 1272 * b bpf_func + 4 1273 * 3. Long branch stub: 1274 * long_branch_stub: 1275 * .long <branch_addr>/<dummy_tramp> 1276 * mflr r11 1277 * bcl 20,31,$+4 1278 * mflr r12 1279 * ld r12, -16(r12) 1280 * mtctr r12 1281 * mtlr r11 // needed to retain ftrace ABI 1282 * bctr 1283 * 1284 * dummy_tramp is used to reduce synchronization requirements. 1285 * 1286 * When attaching a bpf trampoline to a bpf prog, we do not need any 1287 * synchronization here since we always have a valid branch target regardless 1288 * of the order in which the above stores are seen. dummy_tramp ensures that 1289 * the long_branch stub goes to a valid destination on other cpus, even when 1290 * the branch to the long_branch stub is seen before the updated trampoline 1291 * address. 1292 * 1293 * However, when detaching a bpf trampoline from a bpf prog, or if changing 1294 * the bpf trampoline address, we need synchronization to ensure that other 1295 * cpus can no longer branch into the older trampoline so that it can be 1296 * safely freed. bpf_tramp_image_put() uses rcu_tasks to ensure all cpus 1297 * make forward progress, but we still need to ensure that other cpus 1298 * execute isync (or some CSI) so that they don't go back into the 1299 * trampoline again. 1300 */ 1301 int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type old_t, 1302 enum bpf_text_poke_type new_t, void *old_addr, 1303 void *new_addr) 1304 { 1305 unsigned long bpf_func, bpf_func_end, size, offset; 1306 ppc_inst_t old_inst, new_inst; 1307 int ret = 0, branch_flags; 1308 char name[KSYM_NAME_LEN]; 1309 1310 if (IS_ENABLED(CONFIG_PPC32)) 1311 return -EOPNOTSUPP; 1312 1313 bpf_func = (unsigned long)ip; 1314 1315 /* We currently only support poking bpf programs */ 1316 if (!bpf_address_lookup(bpf_func, &size, &offset, name)) { 1317 pr_err("%s (0x%lx): kernel/modules are not supported\n", __func__, bpf_func); 1318 return -EOPNOTSUPP; 1319 } 1320 1321 /* 1322 * If we are not poking at bpf prog entry, then we are simply patching in/out 1323 * an unconditional branch instruction at im->ip_after_call 1324 */ 1325 if (offset) { 1326 if (old_t == BPF_MOD_CALL || new_t == BPF_MOD_CALL) { 1327 pr_err("%s (0x%lx): calls are not supported in bpf prog body\n", __func__, 1328 bpf_func); 1329 return -EOPNOTSUPP; 1330 } 1331 old_inst = ppc_inst(PPC_RAW_NOP()); 1332 if (old_addr) 1333 if (create_branch(&old_inst, ip, (unsigned long)old_addr, 0)) 1334 return -ERANGE; 1335 new_inst = ppc_inst(PPC_RAW_NOP()); 1336 if (new_addr) 1337 if (create_branch(&new_inst, ip, (unsigned long)new_addr, 0)) 1338 return -ERANGE; 1339 mutex_lock(&text_mutex); 1340 ret = bpf_modify_inst(ip, old_inst, new_inst); 1341 mutex_unlock(&text_mutex); 1342 1343 /* Make sure all cpus see the new instruction */ 1344 smp_call_function(do_isync, NULL, 1); 1345 return ret; 1346 } 1347 1348 bpf_func_end = bpf_func + size; 1349 1350 /* Address of the jmp/call instruction in the out-of-line stub */ 1351 ip = (void *)(bpf_func_end - bpf_jit_ool_stub + 4); 1352 1353 if (!is_offset_in_branch_range((long)ip - 4 - bpf_func)) { 1354 pr_err("%s (0x%lx): bpf prog too large, ool stub out of branch range\n", __func__, 1355 bpf_func); 1356 return -ERANGE; 1357 } 1358 1359 old_inst = ppc_inst(PPC_RAW_NOP()); 1360 branch_flags = old_t == BPF_MOD_CALL ? BRANCH_SET_LINK : 0; 1361 if (old_addr) { 1362 if (is_offset_in_branch_range(ip - old_addr)) 1363 create_branch(&old_inst, ip, (unsigned long)old_addr, branch_flags); 1364 else 1365 create_branch(&old_inst, ip, bpf_func_end - bpf_jit_long_branch_stub, 1366 branch_flags); 1367 } 1368 new_inst = ppc_inst(PPC_RAW_NOP()); 1369 branch_flags = new_t == BPF_MOD_CALL ? BRANCH_SET_LINK : 0; 1370 if (new_addr) { 1371 if (is_offset_in_branch_range(ip - new_addr)) 1372 create_branch(&new_inst, ip, (unsigned long)new_addr, branch_flags); 1373 else 1374 create_branch(&new_inst, ip, bpf_func_end - bpf_jit_long_branch_stub, 1375 branch_flags); 1376 } 1377 1378 mutex_lock(&text_mutex); 1379 1380 /* 1381 * 1. Update the address in the long branch stub: 1382 * If new_addr is out of range, we will have to use the long branch stub, so patch new_addr 1383 * here. Otherwise, revert to dummy_tramp, but only if we had patched old_addr here. 1384 */ 1385 if ((new_addr && !is_offset_in_branch_range(new_addr - ip)) || 1386 (old_addr && !is_offset_in_branch_range(old_addr - ip))) 1387 ret = patch_ulong((void *)(bpf_func_end - bpf_jit_long_branch_stub - SZL), 1388 (new_addr && !is_offset_in_branch_range(new_addr - ip)) ? 1389 (unsigned long)new_addr : (unsigned long)dummy_tramp); 1390 if (ret) 1391 goto out; 1392 1393 /* 2. Update the branch/call in the out-of-line stub */ 1394 ret = bpf_modify_inst(ip, old_inst, new_inst); 1395 if (ret) 1396 goto out; 1397 1398 /* 3. Update instruction at bpf prog entry */ 1399 ip = (void *)bpf_func; 1400 if (!old_addr || !new_addr) { 1401 if (!old_addr) { 1402 old_inst = ppc_inst(PPC_RAW_NOP()); 1403 create_branch(&new_inst, ip, bpf_func_end - bpf_jit_ool_stub, 0); 1404 } else { 1405 new_inst = ppc_inst(PPC_RAW_NOP()); 1406 create_branch(&old_inst, ip, bpf_func_end - bpf_jit_ool_stub, 0); 1407 } 1408 ret = bpf_modify_inst(ip, old_inst, new_inst); 1409 } 1410 1411 out: 1412 mutex_unlock(&text_mutex); 1413 1414 /* 1415 * Sync only if we are not attaching a trampoline to a bpf prog so the older 1416 * trampoline can be freed safely. 1417 */ 1418 if (old_addr) 1419 smp_call_function(do_isync, NULL, 1); 1420 1421 return ret; 1422 } 1423