From patchwork Wed Dec 27 08:50:32 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 853115 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [103.22.144.68]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3z66TM4PR8z9s81 for ; Wed, 27 Dec 2017 20:08:23 +1100 (AEDT) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.b="WxlwI5eY"; dkim-atps=neutral Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 3z66TM2y2dzDqZg for ; Wed, 27 Dec 2017 20:08:23 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.b="WxlwI5eY"; dkim-atps=neutral X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=linaro.org (client-ip=2a00:1450:400c:c09::241; helo=mail-wm0-x241.google.com; envelope-from=ard.biesheuvel@linaro.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.b="WxlwI5eY"; dkim-atps=neutral Received: from mail-wm0-x241.google.com (mail-wm0-x241.google.com [IPv6:2a00:1450:400c:c09::241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3z665t2Dr8zDqhc for ; Wed, 27 Dec 2017 19:51:30 +1100 (AEDT) Received: by mail-wm0-x241.google.com with SMTP id y82so38517349wmg.1 for ; Wed, 27 Dec 2017 00:51:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=nmovwwxZQQa2ugEDLnXxoU69CsqWUnhsDto5qVfQljI=; b=WxlwI5eYdKaO3NmcGBbfQz+LK6UKVWOFoMQ+Jyib+BEmRa2fOBlwIMLzNism5cTraH jwShntvWLc1MLEshXs0fqjK4udpfG/RyCibzZzw0w/no0a/0bNsUe8LbcE4bd6Bxc4nm APC55TMa+SgyxGz/NqB151Pg5zBZdpBRBlez4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=nmovwwxZQQa2ugEDLnXxoU69CsqWUnhsDto5qVfQljI=; b=cbRqgvncpKc7VOdZDi4kf+e7hTXADve8dz506KdmaLPIMeZcHkg6CvTQvqz6v/7982 XKUPMebmjAU30kL1SKrK+UluiufCx6LeV4BReuNeI5i0gdPMwZS+dFgChxdx5o+9LwqY g3uORtcYI8mu6hVov2Pc10H1KwMNN8yrOeykddogls/gQ6i1kRDBp9vA+VFioD0nTqZb 3+TwS1oEo9wzcNMOjvOSy5OxNViw8BPxN2mgixYrOmRgGJQ6DcygHpidiX4h7dtqIWsu o5PpYemPEzu5aX+A3pTVUxU+Kra59g0u7FottISwzWReVG6Lba9aXDtP78M5p2c2paRZ G0ZA== X-Gm-Message-State: AKGB3mItJgLKwmElr14jf8bgB/W8Z3EEFE7R2W5gOwwLZ7czxCTIDfea dJ+ItbbxgfMlcjs6/sGYToDmAA== X-Google-Smtp-Source: ACJfBouT6Yv5ICoKDoJ5zQmMjwCc9Y5/e0CV6F9Dks2hPZVOf06j2qsqk5jnO93VU2vB0WsiNsHSTg== X-Received: by 10.28.106.16 with SMTP id f16mr13613978wmc.58.1514364687433; Wed, 27 Dec 2017 00:51:27 -0800 (PST) Received: from localhost.localdomain ([105.137.110.132]) by smtp.gmail.com with ESMTPSA id q74sm32677226wmg.22.2017.12.27.00.51.21 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 27 Dec 2017 00:51:26 -0800 (PST) From: Ard Biesheuvel To: linux-kernel@vger.kernel.org Subject: [PATCH v6 7/8] arm64/kernel: jump_label: use relative references Date: Wed, 27 Dec 2017 08:50:32 +0000 Message-Id: <20171227085033.22389-8-ard.biesheuvel@linaro.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20171227085033.22389-1-ard.biesheuvel@linaro.org> References: <20171227085033.22389-1-ard.biesheuvel@linaro.org> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.24 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-mips@linux-mips.org, Will Deacon , Paul Mackerras , "H. Peter Anvin" , sparclinux@vger.kernel.org, linux-s390@vger.kernel.org, Nicolas Pitre , x86@kernel.org, Russell King , Ingo Molnar , Catalin Marinas , "Serge E. Hallyn" , Petr Mladek , Kees Cook , Arnd Bergmann , Heiko Carstens , Steven Rostedt , James Morris , Josh Poimboeuf , Bjorn Helgaas , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Ard Biesheuvel , linuxppc-dev@lists.ozlabs.org, Ralf Baechle , Thomas Garnier , Sergey Senozhatsky , Jessica Yu , Martin Schwidefsky , Andrew Morton , Linus Torvalds , "David S. Miller" Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" On a randomly chosen distro kernel build for arm64, vmlinux.o shows the following sections, containing jump label entries, and the associated RELA relocation records, respectively: ... [38088] __jump_table PROGBITS 0000000000000000 00e19f30 000000000002ea10 0000000000000000 WA 0 0 8 [38089] .rela__jump_table RELA 0000000000000000 01fd8bb0 000000000008be30 0000000000000018 I 38178 38088 8 ... In other words, we have 190 KB worth of 'struct jump_entry' instances, and 573 KB worth of RELA entries to relocate each entry's code, target and key members. This means the RELA section occupies 10% of the .init segment, and the two sections combined represent 5% of vmlinux's entire memory footprint. So let's switch from 64-bit absolute references to 32-bit relative references: this reduces the size of the __jump_table by 50%, and gets rid of the RELA section entirely. Note that this requires some extra care in the sorting routine, given that the offsets change when entries are moved around in the jump_entry table. Signed-off-by: Ard Biesheuvel --- arch/arm64/include/asm/jump_label.h | 27 ++++++++++++-------- arch/arm64/kernel/jump_label.c | 22 +++++++++++++--- 2 files changed, 36 insertions(+), 13 deletions(-) diff --git a/arch/arm64/include/asm/jump_label.h b/arch/arm64/include/asm/jump_label.h index 9d6e46355c89..5cec68616125 100644 --- a/arch/arm64/include/asm/jump_label.h +++ b/arch/arm64/include/asm/jump_label.h @@ -30,8 +30,8 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran { asm goto("1: nop\n\t" ".pushsection __jump_table, \"aw\"\n\t" - ".align 3\n\t" - ".quad 1b, %l[l_yes], %c0\n\t" + ".align 2\n\t" + ".long 1b - ., %l[l_yes] - ., %c0 - .\n\t" ".popsection\n\t" : : "i"(&((char *)key)[branch]) : : l_yes); @@ -44,8 +44,8 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool { asm goto("1: b %l[l_yes]\n\t" ".pushsection __jump_table, \"aw\"\n\t" - ".align 3\n\t" - ".quad 1b, %l[l_yes], %c0\n\t" + ".align 2\n\t" + ".long 1b - ., %l[l_yes] - ., %c0 - .\n\t" ".popsection\n\t" : : "i"(&((char *)key)[branch]) : : l_yes); @@ -57,19 +57,26 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool typedef u64 jump_label_t; struct jump_entry { - jump_label_t code; - jump_label_t target; - jump_label_t key; + s32 code; + s32 target; + s32 key; }; static inline jump_label_t jump_entry_code(const struct jump_entry *entry) { - return entry->code; + return (jump_label_t)&entry->code + entry->code; +} + +static inline jump_label_t jump_entry_target(const struct jump_entry *entry) +{ + return (jump_label_t)&entry->target + entry->target; } static inline struct static_key *jump_entry_key(const struct jump_entry *entry) { - return (struct static_key *)((unsigned long)entry->key & ~1UL); + unsigned long key = (unsigned long)&entry->key + entry->key; + + return (struct static_key *)(key & ~1UL); } static inline bool jump_entry_is_branch(const struct jump_entry *entry) @@ -87,7 +94,7 @@ static inline void jump_entry_set_module_init(struct jump_entry *entry) entry->code = 0; } -#define jump_label_swap NULL +void jump_label_swap(void *a, void *b, int size); #endif /* __ASSEMBLY__ */ #endif /* __ASM_JUMP_LABEL_H */ diff --git a/arch/arm64/kernel/jump_label.c b/arch/arm64/kernel/jump_label.c index c2dd1ad3e648..2b8e459e91f7 100644 --- a/arch/arm64/kernel/jump_label.c +++ b/arch/arm64/kernel/jump_label.c @@ -25,12 +25,12 @@ void arch_jump_label_transform(struct jump_entry *entry, enum jump_label_type type) { - void *addr = (void *)entry->code; + void *addr = (void *)jump_entry_code(entry); u32 insn; if (type == JUMP_LABEL_JMP) { - insn = aarch64_insn_gen_branch_imm(entry->code, - entry->target, + insn = aarch64_insn_gen_branch_imm(jump_entry_code(entry), + jump_entry_target(entry), AARCH64_INSN_BRANCH_NOLINK); } else { insn = aarch64_insn_gen_nop(); @@ -50,4 +50,20 @@ void arch_jump_label_transform_static(struct jump_entry *entry, */ } +void jump_label_swap(void *a, void *b, int size) +{ + long delta = (unsigned long)a - (unsigned long)b; + struct jump_entry *jea = a; + struct jump_entry *jeb = b; + struct jump_entry tmp = *jea; + + jea->code = jeb->code - delta; + jea->target = jeb->target - delta; + jea->key = jeb->key - delta; + + jeb->code = tmp.code + delta; + jeb->target = tmp.target + delta; + jeb->key = tmp.key + delta; +} + #endif /* HAVE_JUMP_LABEL */