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_kfunc_call(void) 521 { 522 return IS_ENABLED(CONFIG_PPC64); 523 } 524 525 bool bpf_jit_supports_private_stack(void) 526 { 527 return IS_ENABLED(CONFIG_PPC64); 528 } 529 530 bool bpf_jit_supports_fsession(void) 531 { 532 /* 533 * TODO: Remove after validating support 534 * for fsession and trampoline on ppc32. 535 */ 536 if (IS_ENABLED(CONFIG_PPC32)) 537 return -EOPNOTSUPP; 538 return true; 539 } 540 541 bool bpf_jit_supports_arena(void) 542 { 543 return IS_ENABLED(CONFIG_PPC64); 544 } 545 546 bool bpf_jit_supports_far_kfunc_call(void) 547 { 548 return IS_ENABLED(CONFIG_PPC64); 549 } 550 551 bool bpf_jit_supports_insn(struct bpf_insn *insn, bool in_arena) 552 { 553 if (!in_arena) 554 return true; 555 switch (insn->code) { 556 case BPF_STX | BPF_ATOMIC | BPF_H: 557 case BPF_STX | BPF_ATOMIC | BPF_B: 558 case BPF_STX | BPF_ATOMIC | BPF_W: 559 case BPF_STX | BPF_ATOMIC | BPF_DW: 560 if (bpf_atomic_is_load_store(insn)) 561 return false; 562 return IS_ENABLED(CONFIG_PPC64); 563 } 564 return true; 565 } 566 567 bool bpf_jit_supports_percpu_insn(void) 568 { 569 return IS_ENABLED(CONFIG_PPC64); 570 } 571 572 bool bpf_jit_inlines_helper_call(s32 imm) 573 { 574 switch (imm) { 575 case BPF_FUNC_get_smp_processor_id: 576 case BPF_FUNC_get_current_task: 577 case BPF_FUNC_get_current_task_btf: 578 return true; 579 default: 580 return false; 581 } 582 } 583 584 void *arch_alloc_bpf_trampoline(unsigned int size) 585 { 586 return bpf_prog_pack_alloc(size, bpf_jit_fill_ill_insns); 587 } 588 589 void arch_free_bpf_trampoline(void *image, unsigned int size) 590 { 591 bpf_prog_pack_free(image, size); 592 } 593 594 int arch_protect_bpf_trampoline(void *image, unsigned int size) 595 { 596 return 0; 597 } 598 599 static int invoke_bpf_prog(u32 *image, u32 *ro_image, struct codegen_context *ctx, 600 struct bpf_tramp_link *l, int regs_off, int retval_off, 601 int run_ctx_off, bool save_ret) 602 { 603 struct bpf_prog *p = l->link.prog; 604 ppc_inst_t branch_insn; 605 u32 jmp_idx; 606 int ret = 0; 607 608 /* Save cookie */ 609 if (IS_ENABLED(CONFIG_PPC64)) { 610 PPC_LI64(_R3, l->cookie); 611 EMIT(PPC_RAW_STD(_R3, _R1, run_ctx_off + offsetof(struct bpf_tramp_run_ctx, 612 bpf_cookie))); 613 } else { 614 PPC_LI32(_R3, l->cookie >> 32); 615 PPC_LI32(_R4, l->cookie); 616 EMIT(PPC_RAW_STW(_R3, _R1, 617 run_ctx_off + offsetof(struct bpf_tramp_run_ctx, bpf_cookie))); 618 EMIT(PPC_RAW_STW(_R4, _R1, 619 run_ctx_off + offsetof(struct bpf_tramp_run_ctx, bpf_cookie) + 4)); 620 } 621 622 /* __bpf_prog_enter(p, &bpf_tramp_run_ctx) */ 623 PPC_LI_ADDR(_R3, p); 624 EMIT(PPC_RAW_MR(_R25, _R3)); 625 EMIT(PPC_RAW_ADDI(_R4, _R1, run_ctx_off)); 626 ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, 627 (unsigned long)bpf_trampoline_enter(p)); 628 if (ret) 629 return ret; 630 631 /* Remember prog start time returned by __bpf_prog_enter */ 632 EMIT(PPC_RAW_MR(_R26, _R3)); 633 634 /* 635 * if (__bpf_prog_enter(p) == 0) 636 * goto skip_exec_of_prog; 637 * 638 * Emit a nop to be later patched with conditional branch, once offset is known 639 */ 640 EMIT(PPC_RAW_CMPLI(_R3, 0)); 641 jmp_idx = ctx->idx; 642 EMIT(PPC_RAW_NOP()); 643 644 /* p->bpf_func(ctx) */ 645 EMIT(PPC_RAW_ADDI(_R3, _R1, regs_off)); 646 if (!p->jited) 647 PPC_LI_ADDR(_R4, (unsigned long)p->insnsi); 648 /* Account for max possible instructions during dummy pass for size calculation */ 649 if (image && !create_branch(&branch_insn, (u32 *)&ro_image[ctx->idx], 650 (unsigned long)p->bpf_func, 651 BRANCH_SET_LINK)) { 652 image[ctx->idx] = ppc_inst_val(branch_insn); 653 ctx->idx++; 654 } else { 655 EMIT(PPC_RAW_LL(_R12, _R25, offsetof(struct bpf_prog, bpf_func))); 656 EMIT(PPC_RAW_MTCTR(_R12)); 657 EMIT(PPC_RAW_BCTRL()); 658 } 659 660 if (save_ret) 661 EMIT(PPC_RAW_STL(_R3, _R1, retval_off)); 662 663 /* Fix up branch */ 664 if (image) { 665 if (create_cond_branch(&branch_insn, &image[jmp_idx], 666 (unsigned long)&image[ctx->idx], COND_EQ << 16)) 667 return -EINVAL; 668 image[jmp_idx] = ppc_inst_val(branch_insn); 669 } 670 671 /* __bpf_prog_exit(p, start_time, &bpf_tramp_run_ctx) */ 672 EMIT(PPC_RAW_MR(_R3, _R25)); 673 EMIT(PPC_RAW_MR(_R4, _R26)); 674 EMIT(PPC_RAW_ADDI(_R5, _R1, run_ctx_off)); 675 ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, 676 (unsigned long)bpf_trampoline_exit(p)); 677 678 return ret; 679 } 680 681 static int invoke_bpf_mod_ret(u32 *image, u32 *ro_image, struct codegen_context *ctx, 682 struct bpf_tramp_links *tl, int regs_off, int retval_off, 683 int run_ctx_off, u32 *branches) 684 { 685 int i; 686 687 /* 688 * The first fmod_ret program will receive a garbage return value. 689 * Set this to 0 to avoid confusing the program. 690 */ 691 EMIT(PPC_RAW_LI(_R3, 0)); 692 EMIT(PPC_RAW_STL(_R3, _R1, retval_off)); 693 for (i = 0; i < tl->nr_links; i++) { 694 if (invoke_bpf_prog(image, ro_image, ctx, tl->links[i], regs_off, retval_off, 695 run_ctx_off, true)) 696 return -EINVAL; 697 698 /* 699 * mod_ret prog stored return value after prog ctx. Emit: 700 * if (*(u64 *)(ret_val) != 0) 701 * goto do_fexit; 702 */ 703 EMIT(PPC_RAW_LL(_R3, _R1, retval_off)); 704 EMIT(PPC_RAW_CMPLI(_R3, 0)); 705 706 /* 707 * Save the location of the branch and generate a nop, which is 708 * replaced with a conditional jump once do_fexit (i.e. the 709 * start of the fexit invocation) is finalized. 710 */ 711 branches[i] = ctx->idx; 712 EMIT(PPC_RAW_NOP()); 713 } 714 715 return 0; 716 } 717 718 /* 719 * Refer __arch_prepare_bpf_trampoline() for stack component details. 720 * 721 * The tailcall count/reference is present in caller's stack frame. The 722 * tail_call_info is saved at the same offset on the trampoline frame 723 * for the traced function (BPF subprog/callee) to fetch it. 724 */ 725 static void bpf_trampoline_setup_tail_call_info(u32 *image, struct codegen_context *ctx, 726 int bpf_frame_size, int r4_off) 727 { 728 if (IS_ENABLED(CONFIG_PPC64)) { 729 EMIT(PPC_RAW_LD(_R4, _R1, bpf_frame_size)); 730 /* Refer to trampoline's Generated stack layout */ 731 EMIT(PPC_RAW_LD(_R3, _R4, -BPF_PPC_TAILCALL)); 732 733 /* 734 * Setting the tail_call_info in trampoline's frame 735 * depending on if previous frame had value or reference. 736 */ 737 EMIT(PPC_RAW_CMPLWI(_R3, MAX_TAIL_CALL_CNT)); 738 PPC_BCC_CONST_SHORT(COND_GT, 8); 739 EMIT(PPC_RAW_ADDI(_R3, _R4, -BPF_PPC_TAILCALL)); 740 741 /* 742 * Trampoline's tail_call_info is at the same offset, as that of 743 * any bpf program, with reference to previous frame. Update the 744 * address of main's tail_call_info in trampoline frame. 745 */ 746 EMIT(PPC_RAW_STL(_R3, _R1, bpf_frame_size - BPF_PPC_TAILCALL)); 747 } else { 748 /* See bpf_jit_stack_offsetof() and BPF_PPC_TC */ 749 EMIT(PPC_RAW_LL(_R4, _R1, r4_off)); 750 } 751 } 752 753 static void bpf_trampoline_restore_tail_call_cnt(u32 *image, struct codegen_context *ctx, 754 int bpf_frame_size, int r4_off) 755 { 756 if (IS_ENABLED(CONFIG_PPC32)) { 757 /* 758 * Restore tailcall for 32-bit powerpc 759 * See bpf_jit_stack_offsetof() and BPF_PPC_TC 760 */ 761 EMIT(PPC_RAW_STL(_R4, _R1, r4_off)); 762 } 763 } 764 765 static void bpf_trampoline_save_args(u32 *image, struct codegen_context *ctx, 766 int bpf_frame_size, int nr_regs, int regs_off) 767 { 768 int param_save_area_offset; 769 770 param_save_area_offset = bpf_frame_size; 771 param_save_area_offset += STACK_FRAME_MIN_SIZE; /* param save area is past frame header */ 772 773 for (int i = 0; i < nr_regs; i++) { 774 if (i < 8) { 775 EMIT(PPC_RAW_STL(_R3 + i, _R1, regs_off + i * SZL)); 776 } else { 777 EMIT(PPC_RAW_LL(_R3, _R1, param_save_area_offset + i * SZL)); 778 EMIT(PPC_RAW_STL(_R3, _R1, regs_off + i * SZL)); 779 } 780 } 781 } 782 783 /* Used when restoring just the register parameters when returning back */ 784 static void bpf_trampoline_restore_args_regs(u32 *image, struct codegen_context *ctx, 785 int nr_regs, int regs_off) 786 { 787 for (int i = 0; i < nr_regs && i < 8; i++) 788 EMIT(PPC_RAW_LL(_R3 + i, _R1, regs_off + i * SZL)); 789 } 790 791 /* Used when we call into the traced function. Replicate parameter save area */ 792 static void bpf_trampoline_restore_args_stack(u32 *image, struct codegen_context *ctx, 793 int bpf_frame_size, int nr_regs, int regs_off) 794 { 795 int param_save_area_offset; 796 797 param_save_area_offset = bpf_frame_size; 798 param_save_area_offset += STACK_FRAME_MIN_SIZE; /* param save area is past frame header */ 799 800 for (int i = 8; i < nr_regs; i++) { 801 EMIT(PPC_RAW_LL(_R3, _R1, param_save_area_offset + i * SZL)); 802 EMIT(PPC_RAW_STL(_R3, _R1, STACK_FRAME_MIN_SIZE + i * SZL)); 803 } 804 bpf_trampoline_restore_args_regs(image, ctx, nr_regs, regs_off); 805 } 806 807 static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_image, 808 void *rw_image_end, void *ro_image, 809 const struct btf_func_model *m, u32 flags, 810 struct bpf_tramp_links *tlinks, 811 void *func_addr) 812 { 813 int regs_off, func_meta_off, ip_off, run_ctx_off, retval_off; 814 int nvr_off, alt_lr_off, r4_off = 0; 815 struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN]; 816 struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY]; 817 struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT]; 818 int i, ret, nr_regs, retaddr_off, bpf_frame_size = 0; 819 struct codegen_context codegen_ctx, *ctx; 820 int cookie_off, cookie_cnt, cookie_ctx_off; 821 int fsession_cnt = bpf_fsession_cnt(tlinks); 822 u64 func_meta; 823 u32 *image = (u32 *)rw_image; 824 ppc_inst_t branch_insn; 825 u32 *branches = NULL; 826 bool save_ret; 827 828 if (IS_ENABLED(CONFIG_PPC32)) 829 return -EOPNOTSUPP; 830 831 nr_regs = m->nr_args; 832 /* Extra registers for struct arguments */ 833 for (i = 0; i < m->nr_args; i++) 834 if (m->arg_size[i] > SZL) 835 nr_regs += round_up(m->arg_size[i], SZL) / SZL - 1; 836 837 if (nr_regs > MAX_BPF_FUNC_ARGS) 838 return -EOPNOTSUPP; 839 840 ctx = &codegen_ctx; 841 memset(ctx, 0, sizeof(*ctx)); 842 843 /* 844 * Generated stack layout: 845 * 846 * func prev back chain [ back chain ] 847 * [ tail_call_info ] optional - 64-bit powerpc 848 * [ padding ] align stack frame 849 * r4_off [ r4 (tailcallcnt) ] optional - 32-bit powerpc 850 * alt_lr_off [ real lr (ool stub)] optional - actual lr 851 * retaddr_off [ return address ] 852 * [ r26 ] 853 * nvr_off [ r25 ] nvr save area 854 * retval_off [ return value ] 855 * [ reg argN ] 856 * [ ... ] 857 * regs_off [ reg_arg1 ] prog_ctx 858 * func_meta_off [ args count ] ((u64 *)prog_ctx)[-1] 859 * ip_off [ traced function ] ((u64 *)prog_ctx)[-2] 860 * [ stack cookieN ] 861 * [ ... ] 862 * cookie_off [ stack cookie1 ] 863 * run_ctx_off [ bpf_tramp_run_ctx ] 864 * [ reg argN ] 865 * [ ... ] 866 * param_save_area [ reg_arg1 ] min 8 doublewords, per ABI 867 * [ TOC save (64-bit) ] -- 868 * [ LR save (64-bit) ] | header 869 * [ LR save (32-bit) ] | 870 * bpf trampoline frame [ back chain 2 ] -- 871 * 872 */ 873 874 /* Minimum stack frame header */ 875 bpf_frame_size = STACK_FRAME_MIN_SIZE; 876 877 /* 878 * Room for parameter save area. 879 * 880 * As per the ABI, this is required if we call into the traced 881 * function (BPF_TRAMP_F_CALL_ORIG): 882 * - if the function takes more than 8 arguments for the rest to spill onto the stack 883 * - or, if the function has variadic arguments 884 * - or, if this functions's prototype was not available to the caller 885 * 886 * Reserve space for at least 8 registers for now. This can be optimized later. 887 */ 888 bpf_frame_size += (nr_regs > 8 ? nr_regs : 8) * SZL; 889 890 /* Room for struct bpf_tramp_run_ctx */ 891 run_ctx_off = bpf_frame_size; 892 bpf_frame_size += round_up(sizeof(struct bpf_tramp_run_ctx), SZL); 893 894 /* room for session cookies */ 895 cookie_off = bpf_frame_size; 896 cookie_cnt = bpf_fsession_cookie_cnt(tlinks); 897 bpf_frame_size += cookie_cnt * 8; 898 899 /* Room for IP address argument */ 900 ip_off = bpf_frame_size; 901 if (flags & BPF_TRAMP_F_IP_ARG) 902 bpf_frame_size += SZL; 903 904 /* Room for function metadata, arg regs count */ 905 func_meta_off = bpf_frame_size; 906 bpf_frame_size += SZL; 907 908 /* Room for arg regs */ 909 regs_off = bpf_frame_size; 910 bpf_frame_size += nr_regs * SZL; 911 912 /* Room for return value of func_addr or fentry prog */ 913 retval_off = bpf_frame_size; 914 save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET); 915 if (save_ret) 916 bpf_frame_size += SZL; 917 918 /* Room for nvr save area */ 919 nvr_off = bpf_frame_size; 920 bpf_frame_size += 2 * SZL; 921 922 /* Save area for return address */ 923 retaddr_off = bpf_frame_size; 924 bpf_frame_size += SZL; 925 926 /* Optional save area for actual LR in case of ool ftrace */ 927 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) { 928 alt_lr_off = bpf_frame_size; 929 bpf_frame_size += SZL; 930 } 931 932 if (IS_ENABLED(CONFIG_PPC32)) { 933 if (nr_regs < 2) { 934 r4_off = bpf_frame_size; 935 bpf_frame_size += SZL; 936 } else { 937 r4_off = regs_off + SZL; 938 } 939 } 940 941 /* 942 * Save tailcall count pointer at the same offset on the 943 * stack where subprogs expect it 944 */ 945 if ((flags & BPF_TRAMP_F_CALL_ORIG) && 946 (flags & BPF_TRAMP_F_TAIL_CALL_CTX)) 947 bpf_frame_size += BPF_PPC_TAILCALL; 948 949 /* Padding to align stack frame, if any */ 950 bpf_frame_size = round_up(bpf_frame_size, SZL * 2); 951 952 /* Store original return value */ 953 EMIT(PPC_RAW_STL(_R0, _R1, PPC_LR_STKOFF)); 954 955 /* Create our stack frame */ 956 EMIT(PPC_RAW_STLU(_R1, _R1, -bpf_frame_size)); 957 958 /* 64-bit: Save TOC and load kernel TOC */ 959 if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) { 960 EMIT(PPC_RAW_STD(_R2, _R1, 24)); 961 PPC64_LOAD_PACA(); 962 } 963 964 /* 32-bit: save tail call count in r4 */ 965 if (IS_ENABLED(CONFIG_PPC32) && nr_regs < 2) 966 EMIT(PPC_RAW_STL(_R4, _R1, r4_off)); 967 968 bpf_trampoline_save_args(image, ctx, bpf_frame_size, nr_regs, regs_off); 969 970 /* Save our LR/return address */ 971 EMIT(PPC_RAW_MFLR(_R3)); 972 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) 973 EMIT(PPC_RAW_STL(_R3, _R1, alt_lr_off)); 974 else 975 EMIT(PPC_RAW_STL(_R3, _R1, retaddr_off)); 976 977 /* 978 * Derive IP address of the traced function. 979 * In case of CONFIG_PPC_FTRACE_OUT_OF_LINE or BPF program, LR points to the instruction 980 * after the 'bl' instruction in the OOL stub. Refer to ftrace_init_ool_stub() and 981 * bpf_arch_text_poke() for OOL stub of kernel functions and bpf programs respectively. 982 * Relevant stub sequence: 983 * 984 * bl <tramp> 985 * LR (R3) => mtlr r0 986 * b <func_addr+4> 987 * 988 * Recover kernel function/bpf program address from the unconditional 989 * branch instruction at the end of OOL stub. 990 */ 991 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE) || flags & BPF_TRAMP_F_IP_ARG) { 992 EMIT(PPC_RAW_LWZ(_R4, _R3, 4)); 993 EMIT(PPC_RAW_SLWI(_R4, _R4, 6)); 994 EMIT(PPC_RAW_SRAWI(_R4, _R4, 6)); 995 EMIT(PPC_RAW_ADD(_R3, _R3, _R4)); 996 } 997 998 if (flags & BPF_TRAMP_F_IP_ARG) 999 EMIT(PPC_RAW_STL(_R3, _R1, ip_off)); 1000 1001 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) { 1002 /* Fake our LR for BPF_TRAMP_F_CALL_ORIG case */ 1003 EMIT(PPC_RAW_ADDI(_R3, _R3, 4)); 1004 EMIT(PPC_RAW_STL(_R3, _R1, retaddr_off)); 1005 } 1006 1007 /* Save function arg regs count -- see bpf_get_func_arg_cnt() */ 1008 func_meta = nr_regs; 1009 store_func_meta(image, ctx, func_meta, func_meta_off); 1010 1011 /* Save nv regs */ 1012 EMIT(PPC_RAW_STL(_R25, _R1, nvr_off)); 1013 EMIT(PPC_RAW_STL(_R26, _R1, nvr_off + SZL)); 1014 1015 if (flags & BPF_TRAMP_F_CALL_ORIG) { 1016 PPC_LI_ADDR(_R3, (unsigned long)im); 1017 ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, 1018 (unsigned long)__bpf_tramp_enter); 1019 if (ret) 1020 return ret; 1021 } 1022 1023 if (fsession_cnt) { 1024 /* 1025 * Clear all the session cookies' values 1026 * Clear the return value to make sure fentry always get 0 1027 */ 1028 prepare_for_fsession_fentry(image, ctx, cookie_cnt, cookie_off, retval_off); 1029 } 1030 1031 cookie_ctx_off = (regs_off - cookie_off) / 8; 1032 1033 for (i = 0; i < fentry->nr_links; i++) { 1034 if (bpf_prog_calls_session_cookie(fentry->links[i])) { 1035 u64 meta = func_meta | (cookie_ctx_off << BPF_TRAMP_COOKIE_INDEX_SHIFT); 1036 1037 store_func_meta(image, ctx, meta, func_meta_off); 1038 cookie_ctx_off--; 1039 } 1040 1041 if (invoke_bpf_prog(image, ro_image, ctx, fentry->links[i], regs_off, retval_off, 1042 run_ctx_off, flags & BPF_TRAMP_F_RET_FENTRY_RET)) 1043 return -EINVAL; 1044 } 1045 1046 if (fmod_ret->nr_links) { 1047 branches = kcalloc(fmod_ret->nr_links, sizeof(u32), GFP_KERNEL); 1048 if (!branches) 1049 return -ENOMEM; 1050 1051 if (invoke_bpf_mod_ret(image, ro_image, ctx, fmod_ret, regs_off, retval_off, 1052 run_ctx_off, branches)) { 1053 ret = -EINVAL; 1054 goto cleanup; 1055 } 1056 } 1057 1058 /* Call the traced function */ 1059 if (flags & BPF_TRAMP_F_CALL_ORIG) { 1060 /* 1061 * retaddr on trampoline stack points to the correct point in the original function 1062 * with both PPC_FTRACE_OUT_OF_LINE as well as with traditional ftrace instruction 1063 * sequence 1064 */ 1065 EMIT(PPC_RAW_LL(_R3, _R1, retaddr_off)); 1066 EMIT(PPC_RAW_MTCTR(_R3)); 1067 1068 /* Replicate tail_call_cnt before calling the original BPF prog */ 1069 if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) 1070 bpf_trampoline_setup_tail_call_info(image, ctx, bpf_frame_size, r4_off); 1071 1072 /* Restore args */ 1073 bpf_trampoline_restore_args_stack(image, ctx, bpf_frame_size, nr_regs, regs_off); 1074 1075 /* Restore TOC for 64-bit */ 1076 if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) 1077 EMIT(PPC_RAW_LD(_R2, _R1, 24)); 1078 EMIT(PPC_RAW_BCTRL()); 1079 if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) 1080 PPC64_LOAD_PACA(); 1081 1082 /* Store return value for bpf prog to access */ 1083 EMIT(PPC_RAW_STL(_R3, _R1, retval_off)); 1084 1085 /* Restore updated tail_call_cnt */ 1086 if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) 1087 bpf_trampoline_restore_tail_call_cnt(image, ctx, bpf_frame_size, r4_off); 1088 1089 /* Reserve space to patch branch instruction to skip fexit progs */ 1090 if (ro_image) /* image is NULL for dummy pass */ 1091 im->ip_after_call = &((u32 *)ro_image)[ctx->idx]; 1092 EMIT(PPC_RAW_NOP()); 1093 } 1094 1095 /* Update branches saved in invoke_bpf_mod_ret with address of do_fexit */ 1096 for (i = 0; i < fmod_ret->nr_links && image; i++) { 1097 if (create_cond_branch(&branch_insn, &image[branches[i]], 1098 (unsigned long)&image[ctx->idx], COND_NE << 16)) { 1099 ret = -EINVAL; 1100 goto cleanup; 1101 } 1102 1103 image[branches[i]] = ppc_inst_val(branch_insn); 1104 } 1105 1106 /* set the "is_return" flag for fsession */ 1107 func_meta |= (1ULL << BPF_TRAMP_IS_RETURN_SHIFT); 1108 if (fsession_cnt) 1109 store_func_meta(image, ctx, func_meta, func_meta_off); 1110 1111 cookie_ctx_off = (regs_off - cookie_off) / 8; 1112 1113 for (i = 0; i < fexit->nr_links; i++) { 1114 if (bpf_prog_calls_session_cookie(fexit->links[i])) { 1115 u64 meta = func_meta | (cookie_ctx_off << BPF_TRAMP_COOKIE_INDEX_SHIFT); 1116 1117 store_func_meta(image, ctx, meta, func_meta_off); 1118 cookie_ctx_off--; 1119 } 1120 1121 if (invoke_bpf_prog(image, ro_image, ctx, fexit->links[i], regs_off, retval_off, 1122 run_ctx_off, false)) { 1123 ret = -EINVAL; 1124 goto cleanup; 1125 } 1126 } 1127 1128 if (flags & BPF_TRAMP_F_CALL_ORIG) { 1129 if (ro_image) /* image is NULL for dummy pass */ 1130 im->ip_epilogue = &((u32 *)ro_image)[ctx->idx]; 1131 PPC_LI_ADDR(_R3, im); 1132 ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, 1133 (unsigned long)__bpf_tramp_exit); 1134 if (ret) 1135 goto cleanup; 1136 } 1137 1138 if (flags & BPF_TRAMP_F_RESTORE_REGS) 1139 bpf_trampoline_restore_args_regs(image, ctx, nr_regs, regs_off); 1140 1141 /* Restore return value of func_addr or fentry prog */ 1142 if (save_ret) 1143 EMIT(PPC_RAW_LL(_R3, _R1, retval_off)); 1144 1145 /* Restore nv regs */ 1146 EMIT(PPC_RAW_LL(_R26, _R1, nvr_off + SZL)); 1147 EMIT(PPC_RAW_LL(_R25, _R1, nvr_off)); 1148 1149 /* Epilogue */ 1150 if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) 1151 EMIT(PPC_RAW_LD(_R2, _R1, 24)); 1152 if (flags & BPF_TRAMP_F_SKIP_FRAME) { 1153 /* Skip the traced function and return to parent */ 1154 EMIT(PPC_RAW_ADDI(_R1, _R1, bpf_frame_size)); 1155 EMIT(PPC_RAW_LL(_R0, _R1, PPC_LR_STKOFF)); 1156 EMIT(PPC_RAW_MTLR(_R0)); 1157 EMIT(PPC_RAW_BLR()); 1158 } else { 1159 if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) { 1160 EMIT(PPC_RAW_LL(_R0, _R1, alt_lr_off)); 1161 EMIT(PPC_RAW_MTLR(_R0)); 1162 EMIT(PPC_RAW_ADDI(_R1, _R1, bpf_frame_size)); 1163 EMIT(PPC_RAW_LL(_R0, _R1, PPC_LR_STKOFF)); 1164 EMIT(PPC_RAW_BLR()); 1165 } else { 1166 EMIT(PPC_RAW_LL(_R0, _R1, retaddr_off)); 1167 EMIT(PPC_RAW_MTCTR(_R0)); 1168 EMIT(PPC_RAW_ADDI(_R1, _R1, bpf_frame_size)); 1169 EMIT(PPC_RAW_LL(_R0, _R1, PPC_LR_STKOFF)); 1170 EMIT(PPC_RAW_MTLR(_R0)); 1171 EMIT(PPC_RAW_BCTR()); 1172 } 1173 } 1174 1175 /* Make sure the trampoline generation logic doesn't overflow */ 1176 if (image && WARN_ON_ONCE(&image[ctx->idx] > (u32 *)rw_image_end - BPF_INSN_SAFETY)) { 1177 ret = -EFAULT; 1178 goto cleanup; 1179 } 1180 ret = ctx->idx * 4 + BPF_INSN_SAFETY * 4; 1181 1182 cleanup: 1183 kfree(branches); 1184 return ret; 1185 } 1186 1187 int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, 1188 struct bpf_tramp_links *tlinks, void *func_addr) 1189 { 1190 struct bpf_tramp_image im; 1191 int ret; 1192 1193 ret = __arch_prepare_bpf_trampoline(&im, NULL, NULL, NULL, m, flags, tlinks, func_addr); 1194 return ret; 1195 } 1196 1197 int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, 1198 const struct btf_func_model *m, u32 flags, 1199 struct bpf_tramp_links *tlinks, 1200 void *func_addr) 1201 { 1202 u32 size = image_end - image; 1203 void *rw_image, *tmp; 1204 int ret; 1205 1206 /* 1207 * rw_image doesn't need to be in module memory range, so we can 1208 * use kvmalloc. 1209 */ 1210 rw_image = kvmalloc(size, GFP_KERNEL); 1211 if (!rw_image) 1212 return -ENOMEM; 1213 1214 ret = __arch_prepare_bpf_trampoline(im, rw_image, rw_image + size, image, m, 1215 flags, tlinks, func_addr); 1216 if (ret < 0) 1217 goto out; 1218 1219 if (bpf_jit_enable > 1) 1220 bpf_jit_dump(1, ret - BPF_INSN_SAFETY * 4, 1, rw_image); 1221 1222 tmp = bpf_arch_text_copy(image, rw_image, size); 1223 if (IS_ERR(tmp)) 1224 ret = PTR_ERR(tmp); 1225 1226 out: 1227 kvfree(rw_image); 1228 return ret; 1229 } 1230 1231 static int bpf_modify_inst(void *ip, ppc_inst_t old_inst, ppc_inst_t new_inst) 1232 { 1233 ppc_inst_t org_inst; 1234 1235 if (copy_inst_from_kernel_nofault(&org_inst, ip)) { 1236 pr_err("0x%lx: fetching instruction failed\n", (unsigned long)ip); 1237 return -EFAULT; 1238 } 1239 1240 if (!ppc_inst_equal(org_inst, old_inst)) { 1241 pr_err("0x%lx: expected (%08lx) != found (%08lx)\n", 1242 (unsigned long)ip, ppc_inst_as_ulong(old_inst), ppc_inst_as_ulong(org_inst)); 1243 return -EINVAL; 1244 } 1245 1246 if (ppc_inst_equal(old_inst, new_inst)) 1247 return 0; 1248 1249 return patch_instruction(ip, new_inst); 1250 } 1251 1252 static void do_isync(void *info __maybe_unused) 1253 { 1254 isync(); 1255 } 1256 1257 /* 1258 * A 3-step process for bpf prog entry: 1259 * 1. At bpf prog entry, a single nop/b: 1260 * bpf_func: 1261 * [nop|b] ool_stub 1262 * 2. Out-of-line stub: 1263 * ool_stub: 1264 * mflr r0 1265 * [b|bl] <bpf_prog>/<long_branch_stub> 1266 * mtlr r0 // CONFIG_PPC_FTRACE_OUT_OF_LINE only 1267 * b bpf_func + 4 1268 * 3. Long branch stub: 1269 * long_branch_stub: 1270 * .long <branch_addr>/<dummy_tramp> 1271 * mflr r11 1272 * bcl 20,31,$+4 1273 * mflr r12 1274 * ld r12, -16(r12) 1275 * mtctr r12 1276 * mtlr r11 // needed to retain ftrace ABI 1277 * bctr 1278 * 1279 * dummy_tramp is used to reduce synchronization requirements. 1280 * 1281 * When attaching a bpf trampoline to a bpf prog, we do not need any 1282 * synchronization here since we always have a valid branch target regardless 1283 * of the order in which the above stores are seen. dummy_tramp ensures that 1284 * the long_branch stub goes to a valid destination on other cpus, even when 1285 * the branch to the long_branch stub is seen before the updated trampoline 1286 * address. 1287 * 1288 * However, when detaching a bpf trampoline from a bpf prog, or if changing 1289 * the bpf trampoline address, we need synchronization to ensure that other 1290 * cpus can no longer branch into the older trampoline so that it can be 1291 * safely freed. bpf_tramp_image_put() uses rcu_tasks to ensure all cpus 1292 * make forward progress, but we still need to ensure that other cpus 1293 * execute isync (or some CSI) so that they don't go back into the 1294 * trampoline again. 1295 */ 1296 int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type old_t, 1297 enum bpf_text_poke_type new_t, void *old_addr, 1298 void *new_addr) 1299 { 1300 unsigned long bpf_func, bpf_func_end, size, offset; 1301 ppc_inst_t old_inst, new_inst; 1302 int ret = 0, branch_flags; 1303 char name[KSYM_NAME_LEN]; 1304 1305 if (IS_ENABLED(CONFIG_PPC32)) 1306 return -EOPNOTSUPP; 1307 1308 bpf_func = (unsigned long)ip; 1309 1310 /* We currently only support poking bpf programs */ 1311 if (!bpf_address_lookup(bpf_func, &size, &offset, name)) { 1312 pr_err("%s (0x%lx): kernel/modules are not supported\n", __func__, bpf_func); 1313 return -EOPNOTSUPP; 1314 } 1315 1316 /* 1317 * If we are not poking at bpf prog entry, then we are simply patching in/out 1318 * an unconditional branch instruction at im->ip_after_call 1319 */ 1320 if (offset) { 1321 if (old_t == BPF_MOD_CALL || new_t == BPF_MOD_CALL) { 1322 pr_err("%s (0x%lx): calls are not supported in bpf prog body\n", __func__, 1323 bpf_func); 1324 return -EOPNOTSUPP; 1325 } 1326 old_inst = ppc_inst(PPC_RAW_NOP()); 1327 if (old_addr) 1328 if (create_branch(&old_inst, ip, (unsigned long)old_addr, 0)) 1329 return -ERANGE; 1330 new_inst = ppc_inst(PPC_RAW_NOP()); 1331 if (new_addr) 1332 if (create_branch(&new_inst, ip, (unsigned long)new_addr, 0)) 1333 return -ERANGE; 1334 mutex_lock(&text_mutex); 1335 ret = bpf_modify_inst(ip, old_inst, new_inst); 1336 mutex_unlock(&text_mutex); 1337 1338 /* Make sure all cpus see the new instruction */ 1339 smp_call_function(do_isync, NULL, 1); 1340 return ret; 1341 } 1342 1343 bpf_func_end = bpf_func + size; 1344 1345 /* Address of the jmp/call instruction in the out-of-line stub */ 1346 ip = (void *)(bpf_func_end - bpf_jit_ool_stub + 4); 1347 1348 if (!is_offset_in_branch_range((long)ip - 4 - bpf_func)) { 1349 pr_err("%s (0x%lx): bpf prog too large, ool stub out of branch range\n", __func__, 1350 bpf_func); 1351 return -ERANGE; 1352 } 1353 1354 old_inst = ppc_inst(PPC_RAW_NOP()); 1355 branch_flags = old_t == BPF_MOD_CALL ? BRANCH_SET_LINK : 0; 1356 if (old_addr) { 1357 if (is_offset_in_branch_range(ip - old_addr)) 1358 create_branch(&old_inst, ip, (unsigned long)old_addr, branch_flags); 1359 else 1360 create_branch(&old_inst, ip, bpf_func_end - bpf_jit_long_branch_stub, 1361 branch_flags); 1362 } 1363 new_inst = ppc_inst(PPC_RAW_NOP()); 1364 branch_flags = new_t == BPF_MOD_CALL ? BRANCH_SET_LINK : 0; 1365 if (new_addr) { 1366 if (is_offset_in_branch_range(ip - new_addr)) 1367 create_branch(&new_inst, ip, (unsigned long)new_addr, branch_flags); 1368 else 1369 create_branch(&new_inst, ip, bpf_func_end - bpf_jit_long_branch_stub, 1370 branch_flags); 1371 } 1372 1373 mutex_lock(&text_mutex); 1374 1375 /* 1376 * 1. Update the address in the long branch stub: 1377 * If new_addr is out of range, we will have to use the long branch stub, so patch new_addr 1378 * here. Otherwise, revert to dummy_tramp, but only if we had patched old_addr here. 1379 */ 1380 if ((new_addr && !is_offset_in_branch_range(new_addr - ip)) || 1381 (old_addr && !is_offset_in_branch_range(old_addr - ip))) 1382 ret = patch_ulong((void *)(bpf_func_end - bpf_jit_long_branch_stub - SZL), 1383 (new_addr && !is_offset_in_branch_range(new_addr - ip)) ? 1384 (unsigned long)new_addr : (unsigned long)dummy_tramp); 1385 if (ret) 1386 goto out; 1387 1388 /* 2. Update the branch/call in the out-of-line stub */ 1389 ret = bpf_modify_inst(ip, old_inst, new_inst); 1390 if (ret) 1391 goto out; 1392 1393 /* 3. Update instruction at bpf prog entry */ 1394 ip = (void *)bpf_func; 1395 if (!old_addr || !new_addr) { 1396 if (!old_addr) { 1397 old_inst = ppc_inst(PPC_RAW_NOP()); 1398 create_branch(&new_inst, ip, bpf_func_end - bpf_jit_ool_stub, 0); 1399 } else { 1400 new_inst = ppc_inst(PPC_RAW_NOP()); 1401 create_branch(&old_inst, ip, bpf_func_end - bpf_jit_ool_stub, 0); 1402 } 1403 ret = bpf_modify_inst(ip, old_inst, new_inst); 1404 } 1405 1406 out: 1407 mutex_unlock(&text_mutex); 1408 1409 /* 1410 * Sync only if we are not attaching a trampoline to a bpf prog so the older 1411 * trampoline can be freed safely. 1412 */ 1413 if (old_addr) 1414 smp_call_function(do_isync, NULL, 1); 1415 1416 return ret; 1417 } 1418