x86,objtool: Separate unret validation from unwind hints

+7 -7

arch/x86/entry/entry_64.S

··· 388 388 389 389 .if \vector == X86_TRAP_BP 390 390 /* #BP advances %rip to the next instruction */ 391 - UNWIND_HINT_IRET_REGS offset=\has_error_code*8 signal=0 391 + UNWIND_HINT_IRET_ENTRY offset=\has_error_code*8 signal=0 392 392 .else 393 - UNWIND_HINT_IRET_REGS offset=\has_error_code*8 393 + UNWIND_HINT_IRET_ENTRY offset=\has_error_code*8 394 394 .endif 395 395 396 396 ENDBR ··· 461 461 */ 462 462 .macro idtentry_mce_db vector asmsym cfunc 463 463 SYM_CODE_START(\asmsym) 464 - UNWIND_HINT_IRET_REGS 464 + UNWIND_HINT_IRET_ENTRY 465 465 ENDBR 466 466 ASM_CLAC 467 467 cld ··· 518 518 */ 519 519 .macro idtentry_vc vector asmsym cfunc 520 520 SYM_CODE_START(\asmsym) 521 - UNWIND_HINT_IRET_REGS 521 + UNWIND_HINT_IRET_ENTRY 522 522 ENDBR 523 523 ASM_CLAC 524 524 cld ··· 582 582 */ 583 583 .macro idtentry_df vector asmsym cfunc 584 584 SYM_CODE_START(\asmsym) 585 - UNWIND_HINT_IRET_REGS offset=8 585 + UNWIND_HINT_IRET_ENTRY offset=8 586 586 ENDBR 587 587 ASM_CLAC 588 588 cld ··· 1107 1107 FENCE_SWAPGS_KERNEL_ENTRY 1108 1108 CALL_DEPTH_ACCOUNT 1109 1109 leaq 8(%rsp), %rax /* return pt_regs pointer */ 1110 - ANNOTATE_UNRET_END 1110 + VALIDATE_UNRET_END 1111 1111 RET 1112 1112 1113 1113 .Lbstep_iret: ··· 1153 1153 * when PAGE_TABLE_ISOLATION is in use. Do not clobber. 1154 1154 */ 1155 1155 SYM_CODE_START(asm_exc_nmi) 1156 - UNWIND_HINT_IRET_REGS 1156 + UNWIND_HINT_IRET_ENTRY 1157 1157 ENDBR 1158 1158 1159 1159 /*

+4 -4

arch/x86/include/asm/nospec-branch.h

··· 210 210 * Abuse ANNOTATE_RETPOLINE_SAFE on a NOP to indicate UNRET_END, should 211 211 * eventually turn into it's own annotation. 212 212 */ 213 - .macro ANNOTATE_UNRET_END 214 - #ifdef CONFIG_DEBUG_ENTRY 213 + .macro VALIDATE_UNRET_END 214 + #if defined(CONFIG_NOINSTR_VALIDATION) && defined(CONFIG_CPU_UNRET_ENTRY) 215 215 ANNOTATE_RETPOLINE_SAFE 216 216 nop 217 217 #endif ··· 286 286 .macro UNTRAIN_RET 287 287 #if defined(CONFIG_CPU_UNRET_ENTRY) || defined(CONFIG_CPU_IBPB_ENTRY) || \ 288 288 defined(CONFIG_CALL_DEPTH_TRACKING) 289 - ANNOTATE_UNRET_END 289 + VALIDATE_UNRET_END 290 290 ALTERNATIVE_3 "", \ 291 291 CALL_ZEN_UNTRAIN_RET, X86_FEATURE_UNRET, \ 292 292 "call entry_ibpb", X86_FEATURE_ENTRY_IBPB, \ ··· 297 297 .macro UNTRAIN_RET_FROM_CALL 298 298 #if defined(CONFIG_CPU_UNRET_ENTRY) || defined(CONFIG_CPU_IBPB_ENTRY) || \ 299 299 defined(CONFIG_CALL_DEPTH_TRACKING) 300 - ANNOTATE_UNRET_END 300 + VALIDATE_UNRET_END 301 301 ALTERNATIVE_3 "", \ 302 302 CALL_ZEN_UNTRAIN_RET, X86_FEATURE_UNRET, \ 303 303 "call entry_ibpb", X86_FEATURE_ENTRY_IBPB, \

+7 -1

arch/x86/include/asm/unwind_hints.h

··· 12 12 .endm 13 13 14 14 .macro UNWIND_HINT_ENTRY 15 - UNWIND_HINT type=UNWIND_HINT_TYPE_ENTRY end=1 15 + VALIDATE_UNRET_BEGIN 16 + UNWIND_HINT_EMPTY 16 17 .endm 17 18 18 19 .macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 partial=0 signal=1 ··· 51 50 52 51 .macro UNWIND_HINT_IRET_REGS base=%rsp offset=0 signal=1 53 52 UNWIND_HINT_REGS base=\base offset=\offset partial=1 signal=\signal 53 + .endm 54 + 55 + .macro UNWIND_HINT_IRET_ENTRY base=%rsp offset=0 signal=1 56 + VALIDATE_UNRET_BEGIN 57 + UNWIND_HINT_IRET_REGS base=\base offset=\offset signal=\signal 54 58 .endm 55 59 56 60 .macro UNWIND_HINT_FUNC

-5

arch/x86/kernel/head_64.S

··· 390 390 UNWIND_HINT_IRET_REGS offset=8 391 391 ENDBR 392 392 393 - ANNOTATE_UNRET_END 394 - 395 393 /* Build pt_regs */ 396 394 PUSH_AND_CLEAR_REGS 397 395 ··· 449 451 450 452 SYM_CODE_START_LOCAL(early_idt_handler_common) 451 453 UNWIND_HINT_IRET_REGS offset=16 452 - ANNOTATE_UNRET_END 453 454 /* 454 455 * The stack is the hardware frame, an error code or zero, and the 455 456 * vector number. ··· 497 500 SYM_CODE_START_NOALIGN(vc_no_ghcb) 498 501 UNWIND_HINT_IRET_REGS offset=8 499 502 ENDBR 500 - 501 - ANNOTATE_UNRET_END 502 503 503 504 /* Build pt_regs */ 504 505 PUSH_AND_CLEAR_REGS

+16

include/linux/objtool.h

··· 124 124 .popsection 125 125 .endm 126 126 127 + /* 128 + * Use objtool to validate the entry requirement that all code paths do 129 + * VALIDATE_UNRET_END before RET. 130 + * 131 + * NOTE: The macro must be used at the beginning of a global symbol, otherwise 132 + * it will be ignored. 133 + */ 134 + .macro VALIDATE_UNRET_BEGIN 135 + #if defined(CONFIG_NOINSTR_VALIDATION) && defined(CONFIG_CPU_UNRET_ENTRY) 136 + .Lhere_\@: 137 + .pushsection .discard.validate_unret 138 + .long .Lhere_\@ - . 139 + .popsection 140 + #endif 141 + .endm 142 + 127 143 .macro REACHABLE 128 144 .Lhere_\@: 129 145 .pushsection .discard.reachable

+2 -3

include/linux/objtool_types.h

··· 42 42 #define UNWIND_HINT_TYPE_REGS_PARTIAL 2 43 43 /* The below hint types don't have corresponding ORC types */ 44 44 #define UNWIND_HINT_TYPE_FUNC 3 45 - #define UNWIND_HINT_TYPE_ENTRY 4 46 - #define UNWIND_HINT_TYPE_SAVE 5 47 - #define UNWIND_HINT_TYPE_RESTORE 6 45 + #define UNWIND_HINT_TYPE_SAVE 4 46 + #define UNWIND_HINT_TYPE_RESTORE 5 48 47 49 48 #endif /* _LINUX_OBJTOOL_TYPES_H */

+2 -3

tools/include/linux/objtool_types.h

··· 42 42 #define UNWIND_HINT_TYPE_REGS_PARTIAL 2 43 43 /* The below hint types don't have corresponding ORC types */ 44 44 #define UNWIND_HINT_TYPE_FUNC 3 45 - #define UNWIND_HINT_TYPE_ENTRY 4 46 - #define UNWIND_HINT_TYPE_SAVE 5 47 - #define UNWIND_HINT_TYPE_RESTORE 6 45 + #define UNWIND_HINT_TYPE_SAVE 4 46 + #define UNWIND_HINT_TYPE_RESTORE 5 48 47 49 48 #endif /* _LINUX_OBJTOOL_TYPES_H */

+45 -20

tools/objtool/check.c

··· 2307 2307 WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR", 2308 2308 insn->sec, insn->offset); 2309 2309 } 2310 - 2311 - insn->entry = 1; 2312 2310 } 2313 - } 2314 - 2315 - if (hint->type == UNWIND_HINT_TYPE_ENTRY) { 2316 - hint->type = UNWIND_HINT_TYPE_CALL; 2317 - insn->entry = 1; 2318 2311 } 2319 2312 2320 2313 if (hint->type == UNWIND_HINT_TYPE_FUNC) { ··· 2441 2448 2442 2449 return 0; 2443 2450 } 2451 + 2452 + static int read_validate_unret_hints(struct objtool_file *file) 2453 + { 2454 + struct section *sec; 2455 + struct instruction *insn; 2456 + struct reloc *reloc; 2457 + 2458 + sec = find_section_by_name(file->elf, ".rela.discard.validate_unret"); 2459 + if (!sec) 2460 + return 0; 2461 + 2462 + list_for_each_entry(reloc, &sec->reloc_list, list) { 2463 + if (reloc->sym->type != STT_SECTION) { 2464 + WARN("unexpected relocation symbol type in %s", sec->name); 2465 + return -1; 2466 + } 2467 + 2468 + insn = find_insn(file, reloc->sym->sec, reloc->addend); 2469 + if (!insn) { 2470 + WARN("bad .discard.instr_end entry"); 2471 + return -1; 2472 + } 2473 + insn->unret = 1; 2474 + } 2475 + 2476 + return 0; 2477 + } 2478 + 2444 2479 2445 2480 static int read_intra_function_calls(struct objtool_file *file) 2446 2481 { ··· 2685 2664 return ret; 2686 2665 2687 2666 ret = read_instr_hints(file); 2667 + if (ret) 2668 + return ret; 2669 + 2670 + ret = read_validate_unret_hints(file); 2688 2671 if (ret) 2689 2672 return ret; 2690 2673 ··· 3888 3863 /* 3889 3864 * Validate rethunk entry constraint: must untrain RET before the first RET. 3890 3865 * 3891 - * Follow every branch (intra-function) and ensure ANNOTATE_UNRET_END comes 3866 + * Follow every branch (intra-function) and ensure VALIDATE_UNRET_END comes 3892 3867 * before an actual RET instruction. 3893 3868 */ 3894 - static int validate_entry(struct objtool_file *file, struct instruction *insn) 3869 + static int validate_unret(struct objtool_file *file, struct instruction *insn) 3895 3870 { 3896 3871 struct instruction *next, *dest; 3897 3872 int ret, warnings = 0; ··· 3899 3874 for (;;) { 3900 3875 next = next_insn_to_validate(file, insn); 3901 3876 3902 - if (insn->visited & VISITED_ENTRY) 3877 + if (insn->visited & VISITED_UNRET) 3903 3878 return 0; 3904 3879 3905 - insn->visited |= VISITED_ENTRY; 3880 + insn->visited |= VISITED_UNRET; 3906 3881 3907 3882 if (!insn->ignore_alts && insn->alts) { 3908 3883 struct alternative *alt; ··· 3912 3887 if (alt->skip_orig) 3913 3888 skip_orig = true; 3914 3889 3915 - ret = validate_entry(file, alt->insn); 3890 + ret = validate_unret(file, alt->insn); 3916 3891 if (ret) { 3917 3892 if (opts.backtrace) 3918 3893 BT_FUNC("(alt)", insn); ··· 3940 3915 insn->sec, insn->offset); 3941 3916 return -1; 3942 3917 } 3943 - ret = validate_entry(file, insn->jump_dest); 3918 + ret = validate_unret(file, insn->jump_dest); 3944 3919 if (ret) { 3945 3920 if (opts.backtrace) { 3946 3921 BT_FUNC("(branch%s)", insn, ··· 3965 3940 return -1; 3966 3941 } 3967 3942 3968 - ret = validate_entry(file, dest); 3943 + ret = validate_unret(file, dest); 3969 3944 if (ret) { 3970 3945 if (opts.backtrace) 3971 3946 BT_FUNC("(call)", insn); ··· 4001 3976 } 4002 3977 4003 3978 /* 4004 - * Validate that all branches starting at 'insn->entry' encounter UNRET_END 4005 - * before RET. 3979 + * Validate that all branches starting at VALIDATE_UNRET_BEGIN encounter 3980 + * VALIDATE_UNRET_END before RET. 4006 3981 */ 4007 - static int validate_unret(struct objtool_file *file) 3982 + static int validate_unrets(struct objtool_file *file) 4008 3983 { 4009 3984 struct instruction *insn; 4010 3985 int ret, warnings = 0; 4011 3986 4012 3987 for_each_insn(file, insn) { 4013 - if (!insn->entry) 3988 + if (!insn->unret) 4014 3989 continue; 4015 3990 4016 - ret = validate_entry(file, insn); 3991 + ret = validate_unret(file, insn); 4017 3992 if (ret < 0) { 4018 3993 WARN_FUNC("Failed UNRET validation", insn->sec, insn->offset); 4019 3994 return ret; ··· 4632 4607 * Must be after validate_branch() and friends, it plays 4633 4608 * further games with insn->visited. 4634 4609 */ 4635 - ret = validate_unret(file); 4610 + ret = validate_unrets(file); 4636 4611 if (ret < 0) 4637 4612 return ret; 4638 4613 warnings += ret;

+2 -2

tools/objtool/include/objtool/check.h

··· 61 61 restore : 1, 62 62 retpoline_safe : 1, 63 63 noendbr : 1, 64 - entry : 1, 64 + unret : 1, 65 65 visited : 4, 66 66 no_reloc : 1; 67 67 /* 10 bit hole */ ··· 92 92 #define VISITED_BRANCH 0x01 93 93 #define VISITED_BRANCH_UACCESS 0x02 94 94 #define VISITED_BRANCH_MASK 0x03 95 - #define VISITED_ENTRY 0x04 95 + #define VISITED_UNRET 0x04 96 96 97 97 static inline bool is_static_jump(struct instruction *insn) 98 98 {

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