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