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 X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, UNWANTED_LANGUAGE_BODY,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9AA85C433DF for ; Fri, 10 Jul 2020 22:32:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7468F20720 for ; Fri, 10 Jul 2020 22:32:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726645AbgGJWb7 (ORCPT ); Fri, 10 Jul 2020 18:31:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:44816 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726407AbgGJWb7 (ORCPT ); Fri, 10 Jul 2020 18:31:59 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3B33F206F4; Fri, 10 Jul 2020 22:31:57 +0000 (UTC) Date: Fri, 10 Jul 2020 18:31:55 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: x86@kernel.org, linux-kernel@vger.kernel.org, mhiramat@kernel.org, bristot@redhat.com, jbaron@akamai.com, torvalds@linux-foundation.org, tglx@linutronix.de, mingo@kernel.org, namit@vmware.com, hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org, jpoimboe@redhat.com, pbonzini@redhat.com, mathieu.desnoyers@efficios.com, linux@rasmusvillemoes.dk Subject: Re: [PATCH v6 10/17] x86/static_call: Add inline static call implementation for x86-64 Message-ID: <20200710183155.05eae629@oasis.local.home> In-Reply-To: <20200710134336.739394269@infradead.org> References: <20200710133831.943894387@infradead.org> <20200710134336.739394269@infradead.org> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 10 Jul 2020 15:38:41 +0200 Peter Zijlstra wrote: > --- a/tools/objtool/check.c > +++ b/tools/objtool/check.c > @@ -16,6 +16,7 @@ > > #include > #include > +#include > > #define FAKE_JUMP_OFFSET -1 > > @@ -433,6 +434,99 @@ static int add_dead_ends(struct objtool_ > return 0; > } > > +static int create_static_call_sections(struct objtool_file *file) > +{ > + struct section *sec, *reloc_sec; > + struct reloc *reloc; > + struct static_call_site *site; > + struct instruction *insn; > + struct symbol *key_sym; > + char *key_name, *tmp; > + int idx; > + > + sec = find_section_by_name(file->elf, ".static_call_sites"); > + if (sec) { > + INIT_LIST_HEAD(&file->static_call_list); > + WARN("file already has .static_call_sites section, skipping"); > + return 0; > + } > + > + if (list_empty(&file->static_call_list)) > + return 0; > + > + idx = 0; > + list_for_each_entry(insn, &file->static_call_list, static_call_node) > + idx++; > + > + sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE, > + sizeof(struct static_call_site), idx); > + if (!sec) > + return -1; > + > + reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA); > + if (!reloc_sec) > + return -1; > + > + idx = 0; > + list_for_each_entry(insn, &file->static_call_list, static_call_node) { > + > + site = (struct static_call_site *)sec->data->d_buf + idx; > + memset(site, 0, sizeof(struct static_call_site)); > + > + /* populate reloc for 'addr' */ > + reloc = malloc(sizeof(*reloc)); > + if (!reloc) { > + perror("malloc"); > + return -1; > + } > + memset(reloc, 0, sizeof(*reloc)); > + reloc->sym = insn->sec->sym; > + reloc->addend = insn->offset; > + reloc->type = R_X86_64_PC32; > + reloc->offset = idx * sizeof(struct static_call_site); > + reloc->sec = reloc_sec; > + elf_add_reloc(file->elf, reloc); > + > + /* find key symbol */ > + key_name = strdup(insn->call_dest->name); Should check for failed allocation of strdup(). > + if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR, > + strlen(STATIC_CALL_TRAMP_PREFIX_STR))) { > + WARN("static_call: trampoline name malformed: %s", key_name); > + return -1; > + } > + tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN; > + memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN); > + > + key_sym = find_symbol_by_name(file->elf, tmp); > + if (!key_sym) { > + WARN("static_call: can't find static_call_key symbol: %s", tmp); > + return -1; > + } > + free(key_name); > + > + /* populate reloc for 'key' */ > + reloc = malloc(sizeof(*reloc)); > + if (!reloc) { > + perror("malloc"); > + return -1; > + } > + memset(reloc, 0, sizeof(*reloc)); > + reloc->sym = key_sym; > + reloc->addend = 0; > + reloc->type = R_X86_64_PC32; How easy would this be for other architectures to implement this? That is how much of this function is x86 specific? -- Steve > + reloc->offset = idx * sizeof(struct static_call_site) + 4; > + reloc->sec = reloc_sec; > + elf_add_reloc(file->elf, reloc); > + > + idx++; > + } > + > + if (elf_rebuild_reloc_section(file->elf, reloc_sec)) > + return -1; > + > + return 0; > +} > +