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[209.132.180.67]) by mx.google.com with ESMTP id j5-v6si4113271pfh.3.2018.06.27.09.07.03; Wed, 27 Jun 2018 09:07:03 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b="dJd/8Yyx"; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965682AbeF0QHB (ORCPT + 31 others); Wed, 27 Jun 2018 12:07:01 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:33955 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935065AbeF0QGQ (ORCPT ); Wed, 27 Jun 2018 12:06:16 -0400 Received: by mail-wm0-f66.google.com with SMTP id l15-v6so18434174wmc.1 for ; Wed, 27 Jun 2018 09:06:15 -0700 (PDT) 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=3yRjPsLxkB46VvOLi+86pNrf3CoOWXbFse0Dmkmvc3s=; b=dJd/8Yyxskiuc9hVUV5Gfebg3Y4+xz/jCiFF1KxcKQSG52XBlC+lTLyMk2p8oPrGG3 KmsT5bX8P+tY1kJZmQGtm6EgEYtf29u8fShb3/iUI1R2lnezr+6CZn00weWsHco3D7F/ +LKJ4oW6Qi4mWcz25rt1dZmJvl26KrnPeURcI= 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=3yRjPsLxkB46VvOLi+86pNrf3CoOWXbFse0Dmkmvc3s=; b=gqra1e9LSbACLQARq8hNiI0QPl5HzsDTdq+gJWFbgYBy6Z+mWP5OhfJ9+4okCeW0n/ V4GAeWmN5LgnLBCqQfJQLyef8vNMj8hXZdepQGxzh0JrsQaXIt+5LhQgukznLTwWjzQ5 tAIRndZEL3R75vmLlqIhflyzAdNfVK9mazeaAflG+/UfIVCxsM/mf7Jic8nQ5fFvekCv WgC6ISxGGgDq2Krs8yUQ4rmckfJjnHvlllhFBR7SliCBgDw07yZyu2QMWoOtLdIZ6IVr dYtpFAUJPE6neaO5lkx/ofTdUMg9VcAxZ2c8Qi+ncdim+cdEBXL+bzOGFJS7tB55JyKT cHzA== X-Gm-Message-State: APt69E3csB+3dlGot0j2FklVIVc2p3OyhSsjaYIqyqIU6GtCZNkdOiwv VqStsIFGdThouXzRx6NiqnnC++su/bg= X-Received: by 2002:a1c:9c4c:: with SMTP id f73-v6mr5286896wme.141.1530115574543; Wed, 27 Jun 2018 09:06:14 -0700 (PDT) Received: from rev02.home ([2a01:cb1d:112:6f00:4d04:66e:dea8:5b23]) by smtp.gmail.com with ESMTPSA id s2-v6sm7055000wrn.75.2018.06.27.09.06.13 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 27 Jun 2018 09:06:13 -0700 (PDT) From: Ard Biesheuvel To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org Cc: Ard Biesheuvel , Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , Arnd Bergmann , Steven Rostedt , Peter Zijlstra Subject: [PATCH 5/5] x86/kernel: jump_table: use relative references Date: Wed, 27 Jun 2018 18:06:04 +0200 Message-Id: <20180627160604.8154-6-ard.biesheuvel@linaro.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180627160604.8154-1-ard.biesheuvel@linaro.org> References: <20180627160604.8154-1-ard.biesheuvel@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Similar to the arm64 case, 64-bit x86 can benefit from using 32-bit relative references rather than 64-bit absolute ones when emitting struct jump_entry instances. Not only does this reduce the memory footprint of the entries themselves by 50%, it also removes the need for carrying relocation metadata on relocatable builds (i.e., for KASLR) which saves a fair chunk of .init space as well (although the savings are not as dramatic as on arm64) Signed-off-by: Ard Biesheuvel --- arch/x86/Kconfig | 1 + arch/x86/include/asm/jump_label.h | 28 ++++++-------------- tools/objtool/special.c | 4 +-- 3 files changed, 11 insertions(+), 22 deletions(-) -- 2.11.0 diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index e10a3542db7e..dd71258ec1cc 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -118,6 +118,7 @@ config X86 select HAVE_ARCH_AUDITSYSCALL select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE select HAVE_ARCH_JUMP_LABEL + select HAVE_ARCH_JUMP_LABEL_RELATIVE select HAVE_ARCH_KASAN if X86_64 select HAVE_ARCH_KGDB select HAVE_ARCH_MMAP_RND_BITS if MMU diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h index 8c0de4282659..d0f1f25b41d5 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -36,8 +36,8 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran asm_volatile_goto("1:" ".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t" ".pushsection __jump_table, \"aw\" \n\t" - _ASM_ALIGN "\n\t" - _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t" + ".balign 4\n\t" + ".long 1b - ., %l[l_yes] - ., %c0 + %c1 - .\n\t" ".popsection \n\t" : : "i" (key), "i" (branch) : : l_yes); @@ -52,8 +52,8 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool ".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t" "2:\n\t" ".pushsection __jump_table, \"aw\" \n\t" - _ASM_ALIGN "\n\t" - _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t" + ".balign 4\n\t" + ".long 1b - ., %l[l_yes] - ., %c0 + %c1 - .\n\t" ".popsection \n\t" : : "i" (key), "i" (branch) : : l_yes); @@ -62,18 +62,6 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool return true; } -#ifdef CONFIG_X86_64 -typedef u64 jump_label_t; -#else -typedef u32 jump_label_t; -#endif - -struct jump_entry { - jump_label_t code; - jump_label_t target; - jump_label_t key; -}; - #else /* __ASSEMBLY__ */ .macro STATIC_JUMP_IF_TRUE target, key, def @@ -87,8 +75,8 @@ struct jump_entry { .byte STATIC_KEY_INIT_NOP .endif .pushsection __jump_table, "aw" - _ASM_ALIGN - _ASM_PTR .Lstatic_jump_\@, \target, \key + .balign 4 + .long .Lstatic_jump_\@ - ., \target - ., \key - . .popsection .endm @@ -103,8 +91,8 @@ struct jump_entry { .Lstatic_jump_after_\@: .endif .pushsection __jump_table, "aw" - _ASM_ALIGN - _ASM_PTR .Lstatic_jump_\@, \target, \key + 1 + .balign 4 + .long .Lstatic_jump_\@ - ., \target - ., \key + 1 - . .popsection .endm diff --git a/tools/objtool/special.c b/tools/objtool/special.c index 84f001d52322..98ae55b39037 100644 --- a/tools/objtool/special.c +++ b/tools/objtool/special.c @@ -30,9 +30,9 @@ #define EX_ORIG_OFFSET 0 #define EX_NEW_OFFSET 4 -#define JUMP_ENTRY_SIZE 24 +#define JUMP_ENTRY_SIZE 12 #define JUMP_ORIG_OFFSET 0 -#define JUMP_NEW_OFFSET 8 +#define JUMP_NEW_OFFSET 4 #define ALT_ENTRY_SIZE 13 #define ALT_ORIG_OFFSET 0