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Fri, 03 Apr 2026 10:09:19 -0700 (PDT) Received: from localhost.localdomain ([116.128.244.171]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82cf9b3c930sm6588725b3a.17.2026.04.03.10.09.12 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 03 Apr 2026 10:09:18 -0700 (PDT) From: Chengkaitao To: arnd@arndb.de, ast@kernel.org, ihor.solodrai@linux.dev, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, john.fastabend@gmail.com, pengdonglin@xiaomi.com Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, bpf@vger.kernel.org, Kaitao Cheng Subject: [PATCH bpf-next 1/3] bpf: Teach resolve_btfids about the setsc type Date: Sat, 4 Apr 2026 01:08:55 +0800 Message-ID: <20260403170900.58659-2-pilgrimtao@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260403170900.58659-1-pilgrimtao@gmail.com> References: <20260403170900.58659-1-pilgrimtao@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Kaitao Cheng Add .BTF_ids.##sfx subsections under the .BTF_ids output section. The number of entries in each .BTF_ids.##sfx subsection is derived from (__BTF_ids_seg_end_##sfx - sym.st_value). With this, resolve_btfids no longer relies on BTF_SET_END(). That allows kernel code to avoid forcing symbols with similar properties to sit strictly between BTF_SET_START and BTF_SET_END, and it sets the stage for refactoring the BTF_SET* and BTF_ID* macros later. Signed-off-by: Kaitao Cheng --- include/asm-generic/btf_ids.lds.h | 23 ++++++++ include/asm-generic/vmlinux.lds.h | 2 + tools/bpf/resolve_btfids/main.c | 89 +++++++++++++++++++++++++++++-- 3 files changed, 111 insertions(+), 3 deletions(-) create mode 100644 include/asm-generic/btf_ids.lds.h diff --git a/include/asm-generic/btf_ids.lds.h b/include/asm-generic/btf_id= s.lds.h new file mode 100644 index 000000000000..7579ba58f5ff --- /dev/null +++ b/include/asm-generic/btf_ids.lds.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2026 KylinSoft Corporation. + * Copyright (c) 2026 Kaitao Cheng + */ +#ifndef __ASM_GENERIC_BTF_IDS_LDS_H +#define __ASM_GENERIC_BTF_IDS_LDS_H + +/* + * Linker script helpers for CONFIG_DEBUG_INFO_BTF .BTF_ids subsections. + * Input section .BTF_ids.##sfx must match __BTF_IDS_SUBSEC(sfx) in btf_id= s.h. + */ +#ifdef CONFIG_DEBUG_INFO_BTF + +#define BTF_IDS_SUBSEG(sfx) \ + KEEP(*(.BTF_ids.##sfx)) \ + __BTF_ids_seg_end_##sfx =3D .; + +#define BTF_IDS_VERIFIER_SUBSEGS + +#endif /* CONFIG_DEBUG_INFO_BTF */ + +#endif /* __ASM_GENERIC_BTF_IDS_LDS_H */ diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinu= x.lds.h index 1e1580febe4b..96407498629e 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -51,6 +51,7 @@ */ =20 #include +#include =20 #ifndef LOAD_OFFSET #define LOAD_OFFSET 0 @@ -691,6 +692,7 @@ . =3D ALIGN(PAGE_SIZE); \ .BTF_ids : AT(ADDR(.BTF_ids) - LOAD_OFFSET) { \ *(.BTF_ids) \ + BTF_IDS_VERIFIER_SUBSEGS \ } #else #define BTF diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/mai= n.c index f8a91fa7584f..d9b0c9c25eda 100644 --- a/tools/bpf/resolve_btfids/main.c +++ b/tools/bpf/resolve_btfids/main.c @@ -89,6 +89,7 @@ #define BTF_FUNC "func" #define BTF_SET "set" #define BTF_SET8 "set8" +#define BTF_SETSC "setsc" =20 #define ADDR_CNT 100 =20 @@ -104,7 +105,8 @@ enum btf_id_kind { BTF_ID_KIND_NONE, BTF_ID_KIND_SYM, BTF_ID_KIND_SET, - BTF_ID_KIND_SET8 + BTF_ID_KIND_SET8, + BTF_ID_KIND_SETSC, }; =20 struct btf_id { @@ -309,6 +311,77 @@ static int get_id(const char *prefix_end, char *buf, s= ize_t buf_sz) return 0; } =20 +static int elf_sym_value_by_name(struct object *obj, const char *sym_name, + GElf_Addr *val) +{ + Elf_Scn *scn =3D NULL; + GElf_Shdr sh; + int n, i; + + scn =3D elf_getscn(obj->efile.elf, obj->efile.symbols_shndx); + if (!scn || gelf_getshdr(scn, &sh) !=3D &sh) + return -1; + + n =3D sh.sh_size / sh.sh_entsize; + for (i =3D 0; i < n; i++) { + GElf_Sym sym; + char *name; + + if (!gelf_getsym(obj->efile.symbols, i, &sym)) + return -1; + if (sym.st_shndx =3D=3D SHN_UNDEF) + continue; + name =3D elf_strptr(obj->efile.elf, obj->efile.strtabidx, + sym.st_name); + if (name && !strcmp(name, sym_name)) { + *val =3D sym.st_value; + return 0; + } + } + return -1; +} + +/* + * BTF_ID_KIND_SETSC: begin is __BTF_ID__setsc__ (sym.st_value); end= is + * __BTF_ids_seg_end_ from the linker script (btf_ids.lds.h). + */ +static int scatter_set_cnt_from_seg(struct object *obj, struct btf_id *id, + GElf_Addr begin) +{ + GElf_Addr end; + char sym_end[KSYM_NAME_LEN]; + int cnt; + + if (snprintf(sym_end, sizeof(sym_end), "__BTF_ids_seg_end_%s", + id->name) >=3D (int)sizeof(sym_end)) { + pr_err("FAILED scatter set symbol name overflow: %s\n", id->name); + return -1; + } + + if (elf_sym_value_by_name(obj, sym_end, &end)) { + pr_err("FAILED scatter set %s: missing %s in %s\n", + id->name, sym_end, obj->path); + return -1; + } + + if (end <=3D begin || (end - begin) % sizeof(int)) { + pr_err("FAILED scatter set %s: bad span (begin %#lx .. end %s %#lx)\n", + id->name, (unsigned long)begin, sym_end, (unsigned long)end); + return -1; + } + + cnt =3D (int)((unsigned long)(end - begin) / sizeof(int) - 1); + if (cnt < 0) { + pr_err("FAILED scatter set %s: negative cnt\n", id->name); + return -1; + } + id->cnt =3D cnt; + pr_debug("scatter set %s cnt %d span %lu\n", id->name, cnt, + (unsigned long)(end - begin)); + + return 0; +} + static struct btf_id *add_set(struct object *obj, char *name, enum btf_id_= kind kind) { int len =3D strlen(name); @@ -327,6 +400,9 @@ static struct btf_id *add_set(struct object *obj, char = *name, enum btf_id_kind k case BTF_ID_KIND_SET8: prefixlen =3D sizeof(BTF_SET8 "__") - 1; break; + case BTF_ID_KIND_SETSC: + prefixlen =3D sizeof(BTF_SETSC "__") - 1; + break; default: pr_err("Unexpected kind %d passed to %s() for symbol %s\n", kind, __func= __, name); return NULL; @@ -549,6 +625,11 @@ static int symbols_collect(struct object *obj) */ if (id) id->cnt =3D sym.st_size / sizeof(uint64_t) - 1; + /* setsc */ + } else if (!strncmp(prefix, BTF_SETSC, sizeof(BTF_SETSC) - 1)) { + id =3D add_set(obj, prefix, BTF_ID_KIND_SETSC); + if (id && scatter_set_cnt_from_seg(obj, id, sym.st_value)) + return -1; /* set */ } else if (!strncmp(prefix, BTF_SET, sizeof(BTF_SET) - 1)) { id =3D add_set(obj, prefix, BTF_ID_KIND_SET); @@ -690,8 +771,9 @@ static int id_patch(struct object *obj, struct btf_id *= id) int *ptr =3D data->d_buf; int i; =20 - /* For set, set8, id->id may be 0 */ - if (!id->id && id->kind !=3D BTF_ID_KIND_SET && id->kind !=3D BTF_ID_KIND= _SET8) { + /* For set, set8, setsc, id->id may be 0 */ + if (!id->id && id->kind !=3D BTF_ID_KIND_SET && + id->kind !=3D BTF_ID_KIND_SET8 && id->kind !=3D BTF_ID_KIND_SETSC) { pr_err("WARN: resolve_btfids: unresolved symbol %s\n", id->name); warnings++; } @@ -766,6 +848,7 @@ static int sets_patch(struct object *obj) =20 switch (id->kind) { case BTF_ID_KIND_SET: + case BTF_ID_KIND_SETSC: set =3D data->d_buf + off; cnt =3D set->cnt; qsort(set->ids, set->cnt, sizeof(set->ids[0]), cmp_id); --=20 2.43.0 From nobody Tue Apr 7 12:37:03 2026 Received: from mail-pf1-f170.google.com (mail-pf1-f170.google.com [209.85.210.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C3CAE3D3312 for ; Fri, 3 Apr 2026 17:09:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.170 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775236169; cv=none; b=a9ruO/txYUEMkLV+Jm3fVgcHmLc6Oxg/C2lAkp3YM5Tt054M0D7yiUqDIyfq15t1KT0ebd34G42J+4CmQrOqX+owwd2tikdLKX3Q/47/XQePxKpVMcyvXbt6LP+cYVAGmH2X1B6gVH8O3jLmyPSY5cJtqd9vydEFt5bVsTiPBX4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; 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Fri, 03 Apr 2026 10:09:26 -0700 (PDT) Received: from localhost.localdomain ([116.128.244.171]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82cf9b3c930sm6588725b3a.17.2026.04.03.10.09.20 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 03 Apr 2026 10:09:26 -0700 (PDT) From: Chengkaitao To: arnd@arndb.de, ast@kernel.org, ihor.solodrai@linux.dev, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, john.fastabend@gmail.com, pengdonglin@xiaomi.com Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, bpf@vger.kernel.org, Kaitao Cheng Subject: [PATCH bpf-next 2/3] bpf: Introduce BTF_SET/ID_SUB and BPF_VERIF_KFUNC_DEF Date: Sat, 4 Apr 2026 01:08:56 +0800 Message-ID: <20260403170900.58659-3-pilgrimtao@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260403170900.58659-1-pilgrimtao@gmail.com> References: <20260403170900.58659-1-pilgrimtao@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Kaitao Cheng Use BTF_SET_SUB to provide the same kind of grouping as BTF_SET_START/END, so BTF_ID_SUB no longer has to follow the strict sequence (BTF_SET_START, BTF_ID, BTF_SET_END). That lets us scatter BTF_ID_SUB definitions across the file and collect entries with similar properties together, which reduces maintenance overhead. Signed-off-by: Kaitao Cheng --- include/linux/btf_ids.h | 92 +++++++++++++++++++++++++++++++---- tools/include/linux/btf_ids.h | 83 +++++++++++++++++++++++++++---- 2 files changed, 156 insertions(+), 19 deletions(-) diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h index af011db39ab3..c45275c88649 100644 --- a/include/linux/btf_ids.h +++ b/include/linux/btf_ids.h @@ -40,9 +40,9 @@ struct btf_id_set8 { =20 #define BTF_IDS_SECTION ".BTF_ids" =20 -#define ____BTF_ID(symbol, word) \ +#define ____BTF_ID(symbol, word, sec) \ asm( \ -".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \ +".pushsection " sec ",\"a\"; \n" \ ".local " #symbol " ; \n" \ ".type " #symbol ", STT_OBJECT; \n" \ ".size " #symbol ", 4; \n" \ @@ -52,7 +52,7 @@ word \ ".popsection; \n"); =20 #define __BTF_ID(symbol, word) \ - ____BTF_ID(symbol, word) + ____BTF_ID(symbol, word, BTF_IDS_SECTION) =20 #define __ID(prefix) \ __PASTE(__PASTE(prefix, __COUNTER__), __LINE__) @@ -86,19 +86,19 @@ word \ * .zero 4 * */ -#define __BTF_ID_LIST(name, scope) \ +#define __BTF_ID_LIST(name, scope, sec) \ asm( \ -".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \ +".pushsection " sec ",\"a\"; \n" \ "." #scope " " #name "; \n" \ #name ":; \n" \ ".popsection; \n"); =20 #define BTF_ID_LIST(name) \ -__BTF_ID_LIST(name, local) \ +__BTF_ID_LIST(name, local, BTF_IDS_SECTION) \ extern u32 name[]; =20 #define BTF_ID_LIST_GLOBAL(name, n) \ -__BTF_ID_LIST(name, globl) +__BTF_ID_LIST(name, globl, BTF_IDS_SECTION) =20 /* The BTF_ID_LIST_SINGLE macro defines a BTF_ID_LIST with * a single entry. @@ -154,11 +154,11 @@ asm( \ ".popsection; \n"); =20 #define BTF_SET_START(name) \ -__BTF_ID_LIST(name, local) \ +__BTF_ID_LIST(name, local, BTF_IDS_SECTION) \ __BTF_SET_START(name, local) =20 #define BTF_SET_START_GLOBAL(name) \ -__BTF_ID_LIST(name, globl) \ +__BTF_ID_LIST(name, globl, BTF_IDS_SECTION) \ __BTF_SET_START(name, globl) =20 #define BTF_SET_END(name) \ @@ -168,6 +168,75 @@ asm( \ ".popsection; \n"); \ extern struct btf_id_set name; =20 +/* + * BTF_SET_SUB =E2=80=94 place a set in .BTF_ids. so vmlinux.lds.h c= an merge + * multiple input sections into one output .BTF_ids in a fixed order. + * must be a single preprocessor token (e.g. bpf_verif_kfunc_arena). + * + * Member count: begin is __BTF_ID__setsc__ (first in .BTF_ids.); + * end is linker symbol __BTF_ids_seg_end_ (see btf_ids.lds.h). reso= lve_btfids + * uses cnt =3D (end - begin) / 4 - 1. must not contain "__seg__". + * + * extern struct btf_id_set name is emitted by BTF_SET_SUB. BTF_ID_SUB(na= me, ...) + * must use the same as the subsection token. + */ +#define __BTF_IDS_SUBSEC(sub) ".BTF_ids." #sub + +/* Indirection so __ID() expands before ____BTF_ID() stringifies its symbo= l arg. */ +#define __BTF_ID_SUB(sym, sec) ____BTF_ID(sym, "", sec) + +#define BTF_ID_SUB(sub, prefix, name) \ + __BTF_ID_SUB(__ID(__BTF_ID__##prefix##__##name##__), __BTF_IDS_SUBSEC(sub= )) + +#define __BTF_ID_LIST_SUB(name, scope) \ + __BTF_ID_LIST(name, scope, __BTF_IDS_SUBSEC(name)) + +#define __BTF_SET_SUB(name, scope) \ +asm( \ +".pushsection " __BTF_IDS_SUBSEC(name) ",\"a\"; \n" \ +"." #scope " __BTF_ID__setsc__" #name "; \n" \ +"__BTF_ID__setsc__" #name ":; \n" \ +".zero 4 \n" \ +".popsection; \n"); + +#define BTF_SET_SUB(name) \ +extern struct btf_id_set name; \ +__BTF_ID_LIST_SUB(name, local) \ +__BTF_SET_SUB(name, local) + +#include /* CONCATENATE, COUNT_ARGS */ + +/* bpf_verif_kfunc_ (e.g. rbtree_add =E2=86=92 bpf_verif_kfunc_rbtree= _add) */ +#define __BPF_VERIF_KFUNC_SUB(sub) bpf_verif_kfunc_##sub + +/* Cascade: emit first subsection, recurse on the rest (same kfunc @name).= Up to 6 subs. */ +#define __BPF_VERIF_KFUNC_DEF_1(name, s1) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) + +#define __BPF_VERIF_KFUNC_DEF_2(name, s1, s2) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) \ + __BPF_VERIF_KFUNC_DEF_1(name, s2) + +#define __BPF_VERIF_KFUNC_DEF_3(name, s1, s2, s3) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) \ + __BPF_VERIF_KFUNC_DEF_2(name, s2, s3) + +#define __BPF_VERIF_KFUNC_DEF_4(name, s1, s2, s3, s4) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) \ + __BPF_VERIF_KFUNC_DEF_3(name, s2, s3, s4) + +#define __BPF_VERIF_KFUNC_DEF_5(name, s1, s2, s3, s4, s5) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) \ + __BPF_VERIF_KFUNC_DEF_4(name, s2, s3, s4, s5) + +#define __BPF_VERIF_KFUNC_DEF_6(name, s1, s2, s3, s4, s5, s6) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) \ + __BPF_VERIF_KFUNC_DEF_5(name, s2, s3, s4, s5, s6) + +/* First arg: kfunc symbol; rest: subsection suffix tokens matching bpf_ve= rif_kfunc_. */ +#define BPF_VERIF_KFUNC_DEF(name, ...) \ + CONCATENATE(__BPF_VERIF_KFUNC_DEF_, COUNT_ARGS(__VA_ARGS__))(name, __VA_A= RGS__) + /* * The BTF_SET8_START/END macros pair defines sorted list of * BTF IDs and their flags plus its members count, with the @@ -190,7 +259,7 @@ extern struct btf_id_set name; * */ #define __BTF_SET8_START(name, scope, flags) \ -__BTF_ID_LIST(name, local) \ +__BTF_ID_LIST(name, local, BTF_IDS_SECTION) \ asm( \ ".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \ "." #scope " __BTF_ID__set8__" #name "; \n" \ @@ -227,6 +296,9 @@ BTF_SET8_END(name) #define BTF_SET_START(name) static struct btf_id_set __maybe_unused name = =3D { 0 }; #define BTF_SET_START_GLOBAL(name) static struct btf_id_set __maybe_unused= name =3D { 0 }; #define BTF_SET_END(name) +#define BTF_SET_SUB(name) static struct btf_id_set __maybe_unused name =3D= { 0 }; +#define BTF_ID_SUB(sub, prefix, name) +#define BPF_VERIF_KFUNC_DEF(name, ...) #define BTF_SET8_START(name) static struct btf_id_set8 __maybe_unused name= =3D { 0 }; #define BTF_SET8_END(name) #define BTF_KFUNCS_START(name) static struct btf_id_set8 __maybe_unused na= me =3D { .flags =3D BTF_SET8_KFUNCS }; diff --git a/tools/include/linux/btf_ids.h b/tools/include/linux/btf_ids.h index 72ea363d434d..026fd5bfc6d5 100644 --- a/tools/include/linux/btf_ids.h +++ b/tools/include/linux/btf_ids.h @@ -35,9 +35,9 @@ struct btf_id_set8 { =20 #define BTF_IDS_SECTION ".BTF_ids" =20 -#define ____BTF_ID(symbol) \ +#define ____BTF_ID(symbol, sec) \ asm( \ -".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \ +".pushsection " sec ",\"a\"; \n" \ ".local " #symbol " ; \n" \ ".type " #symbol ", STT_OBJECT; \n" \ ".size " #symbol ", 4; \n" \ @@ -46,7 +46,7 @@ asm( \ ".popsection; \n"); =20 #define __BTF_ID(symbol) \ - ____BTF_ID(symbol) + ____BTF_ID(symbol, BTF_IDS_SECTION) =20 #define __ID(prefix) \ __PASTE(__PASTE(prefix, __COUNTER__), __LINE__) @@ -73,19 +73,19 @@ asm( \ * .zero 4 * */ -#define __BTF_ID_LIST(name, scope) \ +#define __BTF_ID_LIST(name, scope, sec) \ asm( \ -".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \ +".pushsection " sec ",\"a\"; \n" \ "." #scope " " #name "; \n" \ #name ":; \n" \ ".popsection; \n"); =20 #define BTF_ID_LIST(name) \ -__BTF_ID_LIST(name, local) \ +__BTF_ID_LIST(name, local, BTF_IDS_SECTION) \ extern u32 name[]; =20 #define BTF_ID_LIST_GLOBAL(name, n) \ -__BTF_ID_LIST(name, globl) +__BTF_ID_LIST(name, globl, BTF_IDS_SECTION) =20 /* The BTF_ID_LIST_SINGLE macro defines a BTF_ID_LIST with * a single entry. @@ -141,11 +141,11 @@ asm( \ ".popsection; \n"); =20 #define BTF_SET_START(name) \ -__BTF_ID_LIST(name, local) \ +__BTF_ID_LIST(name, local, BTF_IDS_SECTION) \ __BTF_SET_START(name, local) =20 #define BTF_SET_START_GLOBAL(name) \ -__BTF_ID_LIST(name, globl) \ +__BTF_ID_LIST(name, globl, BTF_IDS_SECTION) \ __BTF_SET_START(name, globl) =20 #define BTF_SET_END(name) \ @@ -155,6 +155,68 @@ asm( \ ".popsection; \n"); \ extern struct btf_id_set name; =20 +/* + * See include/linux/btf_ids.h: BTF_SET_SUB uses __BTF_ids_seg_end_ = in + * btf_ids.lds.h; begin is __BTF_ID__setsc__. extern struct btf_id_= set name + * is in BTF_SET_SUB. + */ +#define __BTF_IDS_SUBSEC(sub) ".BTF_ids." #sub + +/* Indirection so __ID() expands before ____BTF_ID() stringifies its symbo= l arg. */ +#define __BTF_ID_SUB(sym, sec) ____BTF_ID(sym, sec) + +#define BTF_ID_SUB(sub, prefix, name) \ + __BTF_ID_SUB(__ID(__BTF_ID__##prefix##__##name##__), __BTF_IDS_SUBSEC(sub= )) + +#define __BTF_ID_LIST_SUB(name, scope) \ + __BTF_ID_LIST(name, scope, __BTF_IDS_SUBSEC(name)) + +#define __BTF_SET_SUB(name, scope) \ +asm( \ +".pushsection " __BTF_IDS_SUBSEC(name) ",\"a\"; \n" \ +"." #scope " __BTF_ID__setsc__" #name "; \n" \ +"__BTF_ID__setsc__" #name ":; \n" \ +".zero 4 \n" \ +".popsection; \n"); + +#define BTF_SET_SUB(name) \ +extern struct btf_id_set name; \ +__BTF_ID_LIST_SUB(name, local) \ +__BTF_SET_SUB(name, local) + +#include /* CONCATENATE, COUNT_ARGS */ + +/* bpf_verif_kfunc_ (e.g. rbtree_add =E2=86=92 bpf_verif_kfunc_rbtree= _add) */ +#define __BPF_VERIF_KFUNC_SUB(sub) bpf_verif_kfunc_##sub + +/* Cascade: emit first subsection, recurse on the rest (same kfunc @name).= Up to 6 subs. */ +#define __BPF_VERIF_KFUNC_DEF_1(name, s1) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) + +#define __BPF_VERIF_KFUNC_DEF_2(name, s1, s2) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) \ + __BPF_VERIF_KFUNC_DEF_1(name, s2) + +#define __BPF_VERIF_KFUNC_DEF_3(name, s1, s2, s3) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) \ + __BPF_VERIF_KFUNC_DEF_2(name, s2, s3) + +#define __BPF_VERIF_KFUNC_DEF_4(name, s1, s2, s3, s4) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) \ + __BPF_VERIF_KFUNC_DEF_3(name, s2, s3, s4) + +#define __BPF_VERIF_KFUNC_DEF_5(name, s1, s2, s3, s4, s5) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) \ + __BPF_VERIF_KFUNC_DEF_4(name, s2, s3, s4, s5) + +#define __BPF_VERIF_KFUNC_DEF_6(name, s1, s2, s3, s4, s5, s6) \ + BTF_ID_SUB(__BPF_VERIF_KFUNC_SUB(s1), func, name) \ + __BPF_VERIF_KFUNC_DEF_5(name, s2, s3, s4, s5, s6) + +/* First arg: kfunc symbol; 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Fri, 03 Apr 2026 10:09:34 -0700 (PDT) Received: from localhost.localdomain ([116.128.244.171]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82cf9b3c930sm6588725b3a.17.2026.04.03.10.09.27 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 03 Apr 2026 10:09:33 -0700 (PDT) From: Chengkaitao To: arnd@arndb.de, ast@kernel.org, ihor.solodrai@linux.dev, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, john.fastabend@gmail.com, pengdonglin@xiaomi.com Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, bpf@vger.kernel.org, Kaitao Cheng Subject: [PATCH bpf-next 3/3] bpf: classify rbtree kfuncs with BPF_VERIF_KFUNC_DEF sets Date: Sat, 4 Apr 2026 01:08:57 +0800 Message-ID: <20260403170900.58659-4-pilgrimtao@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260403170900.58659-1-pilgrimtao@gmail.com> References: <20260403170900.58659-1-pilgrimtao@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Kaitao Cheng Remove verifier logic that enumerated special_kfunc_list[KF_bpf_rbtree_*] and compared against it. Use BPF_VERIF_KFUNC_DEF so each kfunc's verifier-facing safety classification is declared in one place next to the implementation. When adding new kfuncs later, you no longer need to thread ad-hoc allowlists through scattered verifier branches=E2=80=94tagging the kfunc on= ce with BPF_VERIF_KFUNC_DEF is enough. This patch only migrates the rbtree kfuncs; other kfunc families can be converted the same way in follow-up work. Signed-off-by: Kaitao Cheng --- include/asm-generic/btf_ids.lds.h | 5 +++- kernel/bpf/helpers.c | 7 +++++ kernel/bpf/verifier.c | 44 +++++++++++-------------------- 3 files changed, 26 insertions(+), 30 deletions(-) diff --git a/include/asm-generic/btf_ids.lds.h b/include/asm-generic/btf_id= s.lds.h index 7579ba58f5ff..879391725d97 100644 --- a/include/asm-generic/btf_ids.lds.h +++ b/include/asm-generic/btf_ids.lds.h @@ -16,7 +16,10 @@ KEEP(*(.BTF_ids.##sfx)) \ __BTF_ids_seg_end_##sfx =3D .; =20 -#define BTF_IDS_VERIFIER_SUBSEGS +#define BTF_IDS_VERIFIER_SUBSEGS \ + BTF_IDS_SUBSEG(bpf_verif_kfunc_rbtree_add) \ + BTF_IDS_SUBSEG(bpf_verif_kfunc_rbtree_graph_node) \ + BTF_IDS_SUBSEG(bpf_verif_kfunc_rbtree_api) =20 #endif /* CONFIG_DEBUG_INFO_BTF */ =20 diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 2d8538bf4cfa..d4a8b0b98210 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2606,6 +2606,7 @@ __bpf_kfunc struct bpf_rb_node *bpf_rbtree_remove(str= uct bpf_rb_root *root, WRITE_ONCE(node_internal->owner, NULL); return (struct bpf_rb_node *)n; } +BPF_VERIF_KFUNC_DEF(bpf_rbtree_remove, rbtree_api, rbtree_graph_node) =20 /* Need to copy rbtree_add_cached's logic here because our 'less' is a BPF * program @@ -2667,6 +2668,7 @@ __bpf_kfunc int bpf_rbtree_add(struct bpf_rb_root *ro= ot, =20 return __bpf_rbtree_add(root, n, (void *)less, meta ? meta->record : NULL= , off); } +BPF_VERIF_KFUNC_DEF(bpf_rbtree_add, rbtree_api, rbtree_add, rbtree_graph_n= ode) =20 __bpf_kfunc int bpf_rbtree_add_impl(struct bpf_rb_root *root, struct bpf_r= b_node *node, bool (less)(struct bpf_rb_node *a, const struct bpf_rb_node *b), @@ -2674,6 +2676,7 @@ __bpf_kfunc int bpf_rbtree_add_impl(struct bpf_rb_roo= t *root, struct bpf_rb_node { return bpf_rbtree_add(root, node, less, meta__ign, off); } +BPF_VERIF_KFUNC_DEF(bpf_rbtree_add_impl, rbtree_api, rbtree_add, rbtree_gr= aph_node) =20 __bpf_kfunc struct bpf_rb_node *bpf_rbtree_first(struct bpf_rb_root *root) { @@ -2681,6 +2684,7 @@ __bpf_kfunc struct bpf_rb_node *bpf_rbtree_first(stru= ct bpf_rb_root *root) =20 return (struct bpf_rb_node *)rb_first_cached(r); } +BPF_VERIF_KFUNC_DEF(bpf_rbtree_first, rbtree_api) =20 __bpf_kfunc struct bpf_rb_node *bpf_rbtree_root(struct bpf_rb_root *root) { @@ -2688,6 +2692,7 @@ __bpf_kfunc struct bpf_rb_node *bpf_rbtree_root(struc= t bpf_rb_root *root) =20 return (struct bpf_rb_node *)r->rb_root.rb_node; } +BPF_VERIF_KFUNC_DEF(bpf_rbtree_root, rbtree_api) =20 __bpf_kfunc struct bpf_rb_node *bpf_rbtree_left(struct bpf_rb_root *root, = struct bpf_rb_node *node) { @@ -2698,6 +2703,7 @@ __bpf_kfunc struct bpf_rb_node *bpf_rbtree_left(struc= t bpf_rb_root *root, struct =20 return (struct bpf_rb_node *)node_internal->rb_node.rb_left; } +BPF_VERIF_KFUNC_DEF(bpf_rbtree_left, rbtree_api, rbtree_graph_node) =20 __bpf_kfunc struct bpf_rb_node *bpf_rbtree_right(struct bpf_rb_root *root,= struct bpf_rb_node *node) { @@ -2708,6 +2714,7 @@ __bpf_kfunc struct bpf_rb_node *bpf_rbtree_right(stru= ct bpf_rb_root *root, struc =20 return (struct bpf_rb_node *)node_internal->rb_node.rb_right; } +BPF_VERIF_KFUNC_DEF(bpf_rbtree_right, rbtree_api, rbtree_graph_node) =20 /** * bpf_task_acquire - Acquire a reference to a task. A task acquired by th= is diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8c1cf2eb6cbb..db9ba47903ef 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12714,6 +12714,10 @@ BTF_ID(func, bpf_session_is_return) BTF_ID(func, bpf_stream_vprintk) BTF_ID(func, bpf_stream_print_stack) =20 +BTF_SET_SUB(bpf_verif_kfunc_rbtree_add) +BTF_SET_SUB(bpf_verif_kfunc_rbtree_graph_node) +BTF_SET_SUB(bpf_verif_kfunc_rbtree_api) + static bool is_bpf_obj_new_kfunc(u32 func_id) { return func_id =3D=3D special_kfunc_list[KF_bpf_obj_new] || @@ -12752,12 +12756,6 @@ static bool is_bpf_list_push_kfunc(u32 func_id) func_id =3D=3D special_kfunc_list[KF_bpf_list_push_back_impl]; } =20 -static bool is_bpf_rbtree_add_kfunc(u32 func_id) -{ - return func_id =3D=3D special_kfunc_list[KF_bpf_rbtree_add] || - func_id =3D=3D special_kfunc_list[KF_bpf_rbtree_add_impl]; -} - static bool is_task_work_add_kfunc(u32 func_id) { return func_id =3D=3D special_kfunc_list[KF_bpf_task_work_schedule_signal= ] || @@ -13162,16 +13160,6 @@ static bool is_bpf_list_api_kfunc(u32 btf_id) btf_id =3D=3D special_kfunc_list[KF_bpf_list_back]; } =20 -static bool is_bpf_rbtree_api_kfunc(u32 btf_id) -{ - return is_bpf_rbtree_add_kfunc(btf_id) || - btf_id =3D=3D special_kfunc_list[KF_bpf_rbtree_remove] || - btf_id =3D=3D special_kfunc_list[KF_bpf_rbtree_first] || - btf_id =3D=3D special_kfunc_list[KF_bpf_rbtree_root] || - btf_id =3D=3D special_kfunc_list[KF_bpf_rbtree_left] || - btf_id =3D=3D special_kfunc_list[KF_bpf_rbtree_right]; -} - static bool is_bpf_iter_num_api_kfunc(u32 btf_id) { return btf_id =3D=3D special_kfunc_list[KF_bpf_iter_num_new] || @@ -13182,7 +13170,7 @@ static bool is_bpf_iter_num_api_kfunc(u32 btf_id) static bool is_bpf_graph_api_kfunc(u32 btf_id) { return is_bpf_list_api_kfunc(btf_id) || - is_bpf_rbtree_api_kfunc(btf_id) || + btf_id_set_contains(&bpf_verif_kfunc_rbtree_api, btf_id) || is_bpf_refcount_acquire_kfunc(btf_id); } =20 @@ -13216,7 +13204,7 @@ static bool kfunc_spin_allowed(u32 btf_id) =20 static bool is_sync_callback_calling_kfunc(u32 btf_id) { - return is_bpf_rbtree_add_kfunc(btf_id); + return btf_id_set_contains(&bpf_verif_kfunc_rbtree_add, btf_id); } =20 static bool is_async_callback_calling_kfunc(u32 btf_id) @@ -13244,7 +13232,7 @@ static bool is_callback_calling_kfunc(u32 btf_id) =20 static bool is_rbtree_lock_required_kfunc(u32 btf_id) { - return is_bpf_rbtree_api_kfunc(btf_id); + return btf_id_set_contains(&bpf_verif_kfunc_rbtree_api, btf_id); } =20 static bool check_kfunc_is_graph_root_api(struct bpf_verifier_env *env, @@ -13258,7 +13246,7 @@ static bool check_kfunc_is_graph_root_api(struct bp= f_verifier_env *env, ret =3D is_bpf_list_api_kfunc(kfunc_btf_id); break; case BPF_RB_ROOT: - ret =3D is_bpf_rbtree_api_kfunc(kfunc_btf_id); + ret =3D btf_id_set_contains(&bpf_verif_kfunc_rbtree_api, kfunc_btf_id); break; default: verbose(env, "verifier internal error: unexpected graph root argument ty= pe %s\n", @@ -13283,10 +13271,7 @@ static bool check_kfunc_is_graph_node_api(struct b= pf_verifier_env *env, ret =3D is_bpf_list_push_kfunc(kfunc_btf_id); break; case BPF_RB_NODE: - ret =3D (is_bpf_rbtree_add_kfunc(kfunc_btf_id) || - kfunc_btf_id =3D=3D special_kfunc_list[KF_bpf_rbtree_remove] || - kfunc_btf_id =3D=3D special_kfunc_list[KF_bpf_rbtree_left] || - kfunc_btf_id =3D=3D special_kfunc_list[KF_bpf_rbtree_right]); + ret =3D btf_id_set_contains(&bpf_verif_kfunc_rbtree_graph_node, kfunc_bt= f_id); break; default: verbose(env, "verifier internal error: unexpected graph node argument ty= pe %s\n", @@ -13823,7 +13808,7 @@ static int check_kfunc_args(struct bpf_verifier_env= *env, struct bpf_kfunc_call_ return ret; break; case KF_ARG_PTR_TO_RB_NODE: - if (is_bpf_rbtree_add_kfunc(meta->func_id)) { + if (btf_id_set_contains(&bpf_verif_kfunc_rbtree_add, meta->func_id)) { if (reg->type !=3D (PTR_TO_BTF_ID | MEM_ALLOC)) { verbose(env, "arg#%d expected pointer to allocated object\n", i); return -EINVAL; @@ -14305,7 +14290,7 @@ static int check_kfunc_call(struct bpf_verifier_env= *env, struct bpf_insn *insn, if (err < 0) return err; =20 - if (is_bpf_rbtree_add_kfunc(meta.func_id)) { + if (btf_id_set_contains(&bpf_verif_kfunc_rbtree_add, meta.func_id)) { err =3D push_callback_call(env, insn, insn_idx, meta.subprogno, set_rbtree_add_callback_state); if (err) { @@ -14409,7 +14394,8 @@ static int check_kfunc_call(struct bpf_verifier_env= *env, struct bpf_insn *insn, return err; } =20 - if (is_bpf_list_push_kfunc(meta.func_id) || is_bpf_rbtree_add_kfunc(meta.= func_id)) { + if (is_bpf_list_push_kfunc(meta.func_id) || + btf_id_set_contains(&bpf_verif_kfunc_rbtree_add, meta.func_id)) { release_ref_obj_id =3D regs[BPF_REG_2].ref_obj_id; insn_aux->insert_off =3D regs[BPF_REG_2].var_off.value; insn_aux->kptr_struct_meta =3D btf_find_struct_meta(meta.arg_btf, meta.a= rg_btf_id); @@ -23438,13 +23424,13 @@ static int fixup_kfunc_call(struct bpf_verifier_e= nv *env, struct bpf_insn *insn, insn_buf[2] =3D *insn; *cnt =3D 3; } else if (is_bpf_list_push_kfunc(desc->func_id) || - is_bpf_rbtree_add_kfunc(desc->func_id)) { + btf_id_set_contains(&bpf_verif_kfunc_rbtree_add, desc->func_id)) { struct btf_struct_meta *kptr_struct_meta =3D env->insn_aux_data[insn_idx= ].kptr_struct_meta; int struct_meta_reg =3D BPF_REG_3; int node_offset_reg =3D BPF_REG_4; =20 /* rbtree_add has extra 'less' arg, so args-to-fixup are in diff regs */ - if (is_bpf_rbtree_add_kfunc(desc->func_id)) { + if (btf_id_set_contains(&bpf_verif_kfunc_rbtree_add, desc->func_id)) { struct_meta_reg =3D BPF_REG_4; node_offset_reg =3D BPF_REG_5; } --=20 2.43.0