From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-189.mta1.migadu.com (out-189.mta1.migadu.com [95.215.58.189]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 063BE2ECE86 for ; Wed, 22 Jul 2026 23:35:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.189 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784763358; cv=none; b=dGg5NHxooRVEry10LtQC82cWFQyhKiInT1J+FIBScRHLCPP/qu5hV86yf/KehKD7HQBqvElpHtTFTe/90sl0UwhV0u3OAgyHcYmc/5Qy4nijY6r7I/73mQvOk2aObwtwxdX/H/EQw2rc9+PjXg2bdyOvaEu5rWlcDEhfEV3HQKA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784763358; c=relaxed/simple; bh=S0pRpgTyeOPk5JZhszv5iZlrVURb94N/Jmqo0kbQBuE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kzJzs95WR51AMueqY3KRzFAWvCDg8VIcW2AwWDG1S20U7Nr2bFuFZjWzCHcUAXfGBCjoDsNpBqgbW+j0R+w75wn5HMcJdrWguyIhyjuj6JUc702cdevFhch68S1ean6v0+cV9CV7cLEUsQxRPMgecunkrL35DhCv7uL3pccA9F4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=JObIAOlc; arc=none smtp.client-ip=95.215.58.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="JObIAOlc" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1784763351; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IgKzIztyg2ynJSPTwAKfWXCZTuSXuB3UVG2hchvJlWA=; b=JObIAOlccjCighFirjZxhaFBImouOlKwiLP99iAt3j2pEH+5lB/WaABX7O41UfyWMqtv+r es5tCOfT1kI9ZvoRbQoPBM9mB32yX6IERm7PMC0Dgqsm1ZfPVRxr5Sh216QeBw+++Fk0T/ cLW7dkUstETfjcOl8lGVWo2YoVWcTg0= From: Ihor Solodrai To: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Eduard Zingerman , Kumar Kartikeya Dwivedi Cc: Benjamin Tissoires , Jiri Kosina , Emil Tsalapatis , Jiri Olsa , bpf@vger.kernel.org, linux-input@vger.kernel.org, kernel-team@meta.com Subject: [PATCH bpf-next v1 2/8] resolve_btfids: Index BTF ID symbols by address Date: Wed, 22 Jul 2026 16:35:12 -0700 Message-ID: <20260722233518.778854-3-ihor.solodrai@linux.dev> In-Reply-To: <20260722233518.778854-1-ihor.solodrai@linux.dev> References: <20260722233518.778854-1-ihor.solodrai@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Keep an address-sorted index of parsed .BTF_ids symbols so that the original BTF_ID symbol name can be recovered from an entry address. Use the index in find_kfunc_flags() to scan BTF_SET8_KFUNCS entries directly and match each entry back to the requested kfunc. Signed-off-by: Ihor Solodrai Reviewed-by: Emil Tsalapatis --- tools/bpf/resolve_btfids/main.c | 96 ++++++++++++++++++++++++--------- 1 file changed, 72 insertions(+), 24 deletions(-) diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c index 183466ddc5f9..3198198b03a7 100644 --- a/tools/bpf/resolve_btfids/main.c +++ b/tools/bpf/resolve_btfids/main.c @@ -119,6 +119,11 @@ struct btf_id { Elf64_Addr addr[ADDR_CNT]; }; +struct addr_sym { + Elf64_Addr addr; + const char *name; +}; + struct object { const char *path; const char *btf_path; @@ -150,6 +155,10 @@ struct object { int nr_structs; int nr_unions; int nr_typedefs; + + struct addr_sym *addr_syms; + u32 addr_syms_cnt; + u32 addr_syms_cap; }; #define KF_IMPLICIT_ARGS (1 << 16) @@ -509,6 +518,40 @@ static int elf_collect(struct object *obj) return 0; } +static int push_addr_sym(struct object *obj, Elf64_Addr addr, const char *name) +{ + if (ensure_mem(&obj->addr_syms, &obj->addr_syms_cap, obj->addr_syms_cnt + 1)) + return -ENOMEM; + + obj->addr_syms[obj->addr_syms_cnt++] = (struct addr_sym){ + .addr = addr, + .name = name, + }; + + return 0; +} + +static int cmp_addr_sym(const void *a, const void *b) +{ + Elf64_Addr aa = ((const struct addr_sym *)a)->addr; + Elf64_Addr ab = ((const struct addr_sym *)b)->addr; + + return (aa > ab) - (aa < ab); +} + +static const char *find_name_by_addr(struct object *obj, Elf64_Addr addr) +{ + struct addr_sym key = { .addr = addr }; + struct addr_sym *res; + + if (!obj->addr_syms_cnt) + return NULL; + + res = bsearch(&key, obj->addr_syms, obj->addr_syms_cnt, + sizeof(*obj->addr_syms), cmp_addr_sym); + return res ? res->name : NULL; +} + static int symbols_collect(struct object *obj) { Elf_Scn *scn = NULL; @@ -602,8 +645,15 @@ static int symbols_collect(struct object *obj) return -1; } id->addr[id->addr_cnt++] = sym.st_value; + + if (push_addr_sym(obj, sym.st_value, id->name)) + return -1; } + if (obj->addr_syms_cnt) + qsort(obj->addr_syms, obj->addr_syms_cnt, + sizeof(*obj->addr_syms), cmp_addr_sym); + return 0; } @@ -957,43 +1007,40 @@ static int collect_decl_tags(struct btf2btf_context *ctx) } /* - * To find the kfunc flags having its struct btf_id (with ELF addresses) - * we need to find the address that is in range of a set8. - * If a set8 is found, then the flags are located at addr + 4 bytes. + * To find kfunc flags, scan BTF_SET8_KFUNCS entries and use the entry + * address to recover the corresponding BTF_ID symbol name. * Return 0 (no flags!) if not found. */ static u32 find_kfunc_flags(struct object *obj, struct btf_id *kfunc_id) { - const u32 *elf_data_ptr = obj->efile.idlist->d_buf; - u64 set_lower_addr, set_upper_addr, addr; + Elf_Data *idlist = obj->efile.idlist; struct btf_id *set_id; struct rb_node *next; - u32 flags; - u64 idx; for (next = rb_first(&obj->sets); next; next = rb_next(next)) { + struct btf_id_set8 *set8; + u64 set_addr; + set_id = rb_entry(next, struct btf_id, rb_node); if (set_id->kind != BTF_ID_KIND_SET8 || set_id->addr_cnt != 1) continue; - set_lower_addr = set_id->addr[0]; - set_upper_addr = set_lower_addr + set_id->cnt * sizeof(u64); + set_addr = set_id->addr[0]; + set8 = idlist->d_buf + (set_addr - obj->efile.idlist_addr); + if (!(set8->flags & BTF_SET8_KFUNCS)) + continue; - for (u32 i = 0; i < kfunc_id->addr_cnt; i++) { - addr = kfunc_id->addr[i]; - /* - * Lower bound is exclusive to skip the 8-byte header of the set. - * Upper bound is inclusive to capture the last entry at offset 8*cnt. - */ - if (set_lower_addr < addr && addr <= set_upper_addr) { - pr_debug("found kfunc %s in BTF_ID_FLAGS %s\n", - kfunc_id->name, set_id->name); - idx = addr - obj->efile.idlist_addr; - idx = idx / sizeof(u32) + 1; - flags = elf_data_ptr[idx]; - - return flags; - } + for (u32 i = 0; i < set_id->cnt; i++) { + size_t off = (char *)&set8->pairs[i] - (char *)set8; + const char *name = find_name_by_addr(obj, set_addr + off); + + if (!name || strcmp(name, kfunc_id->name) != 0) + continue; + + pr_debug("found kfunc %s in BTF_ID_FLAGS %s\n", + kfunc_id->name, set_id->name); + + return set8->pairs[i].flags; } } @@ -1586,6 +1633,7 @@ int main(int argc, const char **argv) btf_id__free_all(&obj.typedefs); btf_id__free_all(&obj.funcs); btf_id__free_all(&obj.sets); + free(obj.addr_syms); if (obj.efile.elf) { elf_end(obj.efile.elf); close(obj.efile.fd); -- 2.55.0