From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB0D0C433F5 for ; Tue, 17 May 2022 15:44:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240468AbiEQPn4 (ORCPT ); Tue, 17 May 2022 11:43:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350608AbiEQPnP (ORCPT ); Tue, 17 May 2022 11:43:15 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8DCEB50B3B for ; Tue, 17 May 2022 08:42:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=C8bFBcYQ8gfp+jZZiMampXlgPGTpsfmScw6kMFrgs3U=; b=UWuNvE0x8LsLtL/c7YtTLBqfmp mjTcSO2ASvIM2tNUw3mLFqt8evsaGid/2l2LFDysiimrcSduyHp/uHz8mxA6UIXAite02w5iexLtE +lcWMFycrvlSjqVrVyO9YDZ+3kPJupACACj3jLSfaUe6TssTo77o1r5phFw58WQBxX2rKcpCPoEQV ddf5FVH41IUvFfiyaVwgKwq6ZbyJo30xAcALAh4Qp/0jQac4i1CDanEJqi5r0ADqxGL7Wvd/2pimO 2zAUEHI6D93D1A2xnRQpe3NYXqHnOnDPgDBRHmXMegGtednF88HANYe/LCmvvtdrhilClDCvkkLZK Ed16ySRQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nqzKo-001H0b-MG; Tue, 17 May 2022 15:42:07 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 7B57D3003AA; Tue, 17 May 2022 17:42:04 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6036A2040ACD7; Tue, 17 May 2022 17:42:04 +0200 (CEST) Date: Tue, 17 May 2022 17:42:04 +0200 From: Peter Zijlstra To: Nathan Chancellor Cc: Josh Poimboeuf , Nick Desaulniers , llvm@lists.linux.dev, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com Subject: Re: objtool "no non-local symbols" error with tip of tree LLVM Message-ID: References: <20220516214005.GQ76023@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 17, 2022 at 05:33:59PM +0200, Peter Zijlstra wrote: > On Mon, May 16, 2022 at 11:40:06PM +0200, Peter Zijlstra wrote: > > Does something simple like this work? If not, I'll try and reproduce > > tomorrow, it shouldn't be too hard to fix. > > Oh, man, I so shouldn't have said that :/ > > I have something that almost works, except it now mightly upsets > modpost. > > I'm not entirely sure how the old code worked as well as it did. Oh > well, I'll get it sorted. Pff, it's been a *long* day.. here this works. --- tools/objtool/elf.c | 191 ++++++++++++++++++++++++++++++++++------------------ 1 file changed, 125 insertions(+), 66 deletions(-) diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index ebf2ba5755c1..a9c3e27527de 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -600,24 +600,24 @@ static void elf_dirty_reloc_sym(struct elf *elf, struct symbol *sym) } /* - * Move the first global symbol, as per sh_info, into a new, higher symbol - * index. This fees up the shndx for a new local symbol. + * The libelf API is terrible; gelf_update_sym*() takes a data block relative + * index value. As such, iterate the data blocks and adjust index until it fits. + * + * If no data block is found, allow adding a new data block provided the index + * is only one past the end. */ -static int elf_move_global_symbol(struct elf *elf, struct section *symtab, - struct section *symtab_shndx) +static int elf_update_symbol(struct elf *elf, struct section *symtab, + struct section *symtab_shndx, struct symbol *sym) { - Elf_Data *data, *shndx_data = NULL; - Elf32_Word first_non_local; - struct symbol *sym; - Elf_Scn *s; + Elf_Data *symtab_data = NULL, *shndx_data = NULL; + Elf32_Word shndx = sym->sec->idx; + Elf_Scn *s, *t = NULL; + int size, idx = sym->idx; - first_non_local = symtab->sh.sh_info; - - sym = find_symbol_by_index(elf, first_non_local); - if (!sym) { - WARN("no non-local symbols !?"); - return first_non_local; - } + if (elf->ehdr.e_ident[EI_CLASS] == ELFCLASS32) + size = sizeof(Elf32_Sym); + else + size = sizeof(Elf64_Sym); s = elf_getscn(elf->elf, symtab->idx); if (!s) { @@ -625,79 +625,120 @@ static int elf_move_global_symbol(struct elf *elf, struct section *symtab, return -1; } - data = elf_newdata(s); - if (!data) { - WARN_ELF("elf_newdata"); - return -1; + if (symtab_shndx) { + t = elf_getscn(elf->elf, symtab_shndx->idx); + if (!t) { + WARN_ELF("elf_getscn"); + return -1; + } } - data->d_buf = &sym->sym; - data->d_size = sizeof(sym->sym); - data->d_align = 1; - data->d_type = ELF_T_SYM; + for (;;) { + symtab_data = elf_getdata(s, symtab_data); + if (t) + shndx_data = elf_getdata(t, shndx_data); - sym->idx = symtab->sh.sh_size / sizeof(sym->sym); - elf_dirty_reloc_sym(elf, sym); + if (!symtab_data) { + if (!idx) { + void *buf; - symtab->sh.sh_info += 1; - symtab->sh.sh_size += data->d_size; - symtab->changed = true; + symtab_data = elf_newdata(s); + if (t) + shndx_data = elf_newdata(t); - if (symtab_shndx) { - s = elf_getscn(elf->elf, symtab_shndx->idx); - if (!s) { - WARN_ELF("elf_getscn"); + buf = calloc(1, size); + if (!buf) { + WARN("malloc"); + return -1; + } + + symtab_data->d_buf = buf; + symtab_data->d_size = size; + symtab_data->d_align = 1; + symtab_data->d_type = ELF_T_SYM; + + symtab->sh.sh_size += size; + symtab->changed = true; + + if (t) { + shndx_data->d_buf = &sym->sec->idx; + shndx_data->d_size = sizeof(Elf32_Word); + shndx_data->d_align = 4; + shndx_data->d_type = ELF_T_WORD; + + symtab_shndx->sh.sh_size += 4; + symtab_shndx->changed = true; + } + + break; + } + + WARN("index out of range"); return -1; } - shndx_data = elf_newdata(s); - if (!shndx_data) { - WARN_ELF("elf_newshndx_data"); + if (!symtab_data->d_size) { + WARN("zero size data"); return -1; } - shndx_data->d_buf = &sym->sec->idx; - shndx_data->d_size = sizeof(Elf32_Word); - shndx_data->d_align = 4; - shndx_data->d_type = ELF_T_WORD; + if (idx * size < symtab_data->d_size) + break; - symtab_shndx->sh.sh_size += 4; - symtab_shndx->changed = true; + idx -= symtab_data->d_size / size; } - return first_non_local; + if (idx < 0) { + WARN("negative index"); + return -1; + } + + if (shndx >= SHN_UNDEF && shndx < SHN_LORESERVE) { + sym->sym.st_shndx = shndx; + if (!shndx_data) + shndx = 0; + } else { + sym->sym.st_shndx = SHN_XINDEX; + if (!shndx_data) { + WARN("no .symtab_shndx"); + return -1; + } + } + + if (!gelf_update_symshndx(symtab_data, shndx_data, idx, &sym->sym, shndx)) { + WARN_ELF("gelf_update_symshndx"); + return -1; + } + + return 0; } static struct symbol * elf_create_section_symbol(struct elf *elf, struct section *sec) { struct section *symtab, *symtab_shndx; - Elf_Data *shndx_data = NULL; - struct symbol *sym; - Elf32_Word shndx; + Elf32_Word first_non_local, new; + struct symbol *sym, *old; + int size; + + if (elf->ehdr.e_ident[EI_CLASS] == ELFCLASS32) + size = sizeof(Elf32_Sym); + else + size = sizeof(Elf64_Sym); symtab = find_section_by_name(elf, ".symtab"); if (symtab) { symtab_shndx = find_section_by_name(elf, ".symtab_shndx"); - if (symtab_shndx) - shndx_data = symtab_shndx->data; } else { WARN("no .symtab"); return NULL; } - sym = malloc(sizeof(*sym)); + sym = calloc(1, sizeof(*sym)); if (!sym) { perror("malloc"); return NULL; } - memset(sym, 0, sizeof(*sym)); - - sym->idx = elf_move_global_symbol(elf, symtab, symtab_shndx); - if (sym->idx < 0) { - WARN("elf_move_global_symbol"); - return NULL; - } sym->name = sec->name; sym->sec = sec; @@ -707,24 +748,42 @@ elf_create_section_symbol(struct elf *elf, struct section *sec) // st_other 0 // st_value 0 // st_size 0 - shndx = sec->idx; - if (shndx >= SHN_UNDEF && shndx < SHN_LORESERVE) { - sym->sym.st_shndx = shndx; - if (!shndx_data) - shndx = 0; - } else { - sym->sym.st_shndx = SHN_XINDEX; - if (!shndx_data) { - WARN("no .symtab_shndx"); + + new = symtab->sh.sh_size / size; + + /* + * Move the first global symbol, as per sh_info, into a new, higher + * symbol index. This fees up a spot for a new local symbol. + */ + first_non_local = symtab->sh.sh_info; + old = find_symbol_by_index(elf, first_non_local); + if (old) { + old->idx = new; + + hlist_del(&old->hash); + elf_hash_add(symbol, &old->hash, old->idx); + + elf_dirty_reloc_sym(elf, old); + + if (elf_update_symbol(elf, symtab, symtab_shndx, old)) { + WARN("elf_update_symbol move"); return NULL; } + + new = first_non_local; } - if (!gelf_update_symshndx(symtab->data, shndx_data, sym->idx, &sym->sym, shndx)) { - WARN_ELF("gelf_update_symshndx"); + sym->idx = new; + if (elf_update_symbol(elf, symtab, symtab_shndx, sym)) { + WARN("elf_update_symbol"); return NULL; } + /* + * Either way, we added a LOCAL symbol. + */ + symtab->sh.sh_info += 1; + elf_add_symbol(elf, sym); return sym;