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=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS 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 7A0C7C352AA for ; Mon, 7 Oct 2019 11:25:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4753421D7E for ; Mon, 7 Oct 2019 11:25:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="XbKDMWvb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728195AbfJGLZK (ORCPT ); Mon, 7 Oct 2019 07:25:10 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:50242 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727795AbfJGLXk (ORCPT ); Mon, 7 Oct 2019 07:23:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=2DP7SdddmBPCqTl/EX42Xv/iKdY/IVrkhlnqstt7XuU=; b=XbKDMWvbnvsAV/H/eZiu8yg+lp qgXEq2x4REFjFVe6WtV9Ii7Mnl/dqpqv1s9H/ZYW8vbvCN5s581lC7tQvlD6iudnSJdeNpPQLlev+ w68udFUw4rZ+RhSEI7Sc4e+Sbyb0dA/ztS6UuO9B5kBM58KCzAjO97ijAZ3X6g8uFH/utRDynIYst ExCv+PBe27TFH+pYcuqHkFOPZ/CgLjXVzKF9ysSe1Dva0+PYPq+y0VbrHXJz/UlZMYZbIhMuocnLO l8R0be989o1MFScsC55yZE/jcntUZ8Ji4DsZr4gexMoKBvMwemodlqhAYpL/2T3ve/MDudslNBkYV fk84iJMw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.2 #3 (Red Hat Linux)) id 1iHR6y-0003Gx-5J; Mon, 07 Oct 2019 11:23:32 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 38FDD30709E; Mon, 7 Oct 2019 13:22:36 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id DD155202A1952; Mon, 7 Oct 2019 13:23:26 +0200 (CEST) Message-Id: <20191007083831.15486812.0@infradead.org> User-Agent: quilt/0.65 Date: Mon, 07 Oct 2019 10:27:19 +0200 From: Peter Zijlstra To: x86@kernel.org Cc: peterz@infradead.org, linux-kernel@vger.kernel.org, rostedt@goodmis.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 Subject: [PATCH v2 11/13] static_call: Handle tail-calls References: <20191007082708.01393931.1@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org GCC can turn our static_call(name)(args...) into a tail call, in which case we get a JMP.d32 into the trampoline (which then does a further tail-call). Teach objtool to recognise and mark these in .static_call_sites and adjust the code patching to deal with this. Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/kernel/static_call.c | 4 ++-- include/linux/static_call.h | 4 ++-- include/linux/static_call_types.h | 7 +++++++ kernel/static_call.c | 21 +++++++++++++-------- tools/include/linux/static_call_types.h | 7 +++++++ tools/objtool/check.c | 18 +++++++++++++----- 6 files changed, 44 insertions(+), 17 deletions(-) --- a/arch/x86/kernel/static_call.c +++ b/arch/x86/kernel/static_call.c @@ -41,7 +41,7 @@ static void __static_call_transform(void text_poke_bp(insn, code, size, NULL); } -void arch_static_call_transform(void *site, void *tramp, void *func) +void arch_static_call_transform(void *site, void *tramp, void *func, bool tail) { mutex_lock(&text_mutex); @@ -49,7 +49,7 @@ void arch_static_call_transform(void *si __static_call_transform(tramp, jmp + !func, func); if (IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE) && site) - __static_call_transform(site, !func, func); + __static_call_transform(site, 2*tail + !func, func); mutex_unlock(&text_mutex); } --- a/include/linux/static_call.h +++ b/include/linux/static_call.h @@ -64,7 +64,7 @@ /* * Either @site or @tramp can be NULL. */ -extern void arch_static_call_transform(void *site, void *tramp, void *func); +extern void arch_static_call_transform(void *site, void *tramp, void *func, bool tail); #endif @@ -137,7 +137,7 @@ void __static_call_update(struct static_ { cpus_read_lock(); WRITE_ONCE(key->func, func); - arch_static_call_transform(NULL, tramp, func); + arch_static_call_transform(NULL, tramp, func, false); cpus_read_unlock(); } --- a/include/linux/static_call_types.h +++ b/include/linux/static_call_types.h @@ -13,6 +13,13 @@ #define STATIC_CALL_TRAMP_STR(name) __stringify(STATIC_CALL_TRAMP(name)) /* + * Flags in the low bits of static_call_site::key. + */ +#define STATIC_CALL_SITE_TAIL 1UL /* tail call */ +#define STATIC_CALL_SITE_INIT 2UL /* init section */ +#define STATIC_CALL_SITE_FLAGS 3UL + +/* * The static call site table needs to be created by external tooling (objtool * or a compiler plugin). */ --- a/kernel/static_call.c +++ b/kernel/static_call.c @@ -15,8 +15,6 @@ extern struct static_call_site __start_s static bool static_call_initialized; -#define STATIC_CALL_INIT 1UL - /* mutex to protect key modules/sites */ static DEFINE_MUTEX(static_call_mutex); @@ -39,18 +37,23 @@ static inline void *static_call_addr(str static inline struct static_call_key *static_call_key(const struct static_call_site *site) { return (struct static_call_key *) - (((long)site->key + (long)&site->key) & ~STATIC_CALL_INIT); + (((long)site->key + (long)&site->key) & ~STATIC_CALL_SITE_FLAGS); } /* These assume the key is word-aligned. */ static inline bool static_call_is_init(struct static_call_site *site) { - return ((long)site->key + (long)&site->key) & STATIC_CALL_INIT; + return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_INIT; +} + +static inline bool static_call_is_tail(struct static_call_site *site) +{ + return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_TAIL; } static inline void static_call_set_init(struct static_call_site *site) { - site->key = ((long)static_call_key(site) | STATIC_CALL_INIT) - + site->key = ((long)static_call_key(site) | STATIC_CALL_SITE_INIT) - (long)&site->key; } @@ -104,7 +107,7 @@ void __static_call_update(struct static_ key->func = func; - arch_static_call_transform(NULL, tramp, func); + arch_static_call_transform(NULL, tramp, func, false); /* * If uninitialized, we'll not update the callsites, but they still @@ -153,7 +156,8 @@ void __static_call_update(struct static_ continue; } - arch_static_call_transform(site_addr, NULL, func); + arch_static_call_transform(site_addr, NULL, func, + static_call_is_tail(site)); } } @@ -197,7 +201,8 @@ static int __static_call_init(struct mod key->next = site_mod; } - arch_static_call_transform(site_addr, NULL, key->func); + arch_static_call_transform(site_addr, NULL, key->func, + static_call_is_tail(site)); } return 0; --- a/tools/include/linux/static_call_types.h +++ b/tools/include/linux/static_call_types.h @@ -13,6 +13,13 @@ #define STATIC_CALL_TRAMP_STR(name) __stringify(STATIC_CALL_TRAMP(name)) /* + * Flags in the low bits of static_call_site::key. + */ +#define STATIC_CALL_SITE_TAIL 1UL /* tail call */ +#define STATIC_CALL_SITE_INIT 2UL /* init section */ +#define STATIC_CALL_SITE_FLAGS 3UL + +/* * The static call site table needs to be created by external tooling (objtool * or a compiler plugin). */ --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -585,6 +585,10 @@ static int add_jump_destinations(struct } else { /* external sibling call */ insn->call_dest = rela->sym; + if (insn->call_dest->static_call_tramp) { + list_add_tail(&insn->static_call_node, + &file->static_call_list); + } continue; } @@ -636,6 +640,10 @@ static int add_jump_destinations(struct /* internal sibling call */ insn->call_dest = insn->jump_dest->func; + if (insn->call_dest->static_call_tramp) { + list_add_tail(&insn->static_call_node, + &file->static_call_list); + } } } } @@ -1348,6 +1356,10 @@ static int decode_sections(struct objtoo if (ret) return ret; + ret = read_static_call_tramps(file); + if (ret) + return ret; + ret = add_jump_destinations(file); if (ret) return ret; @@ -1372,10 +1384,6 @@ static int decode_sections(struct objtoo if (ret) return ret; - ret = read_static_call_tramps(file); - if (ret) - return ret; - return 0; } @@ -2505,7 +2513,7 @@ static int create_static_call_sections(s } memset(rela, 0, sizeof(*rela)); rela->sym = key_sym; - rela->addend = 0; + rela->addend = is_sibling_call(insn) ? STATIC_CALL_SITE_TAIL : 0; rela->type = R_X86_64_PC32; rela->offset = idx * sizeof(struct static_call_site) + 4; list_add_tail(&rela->list, &rela_sec->rela_list);