From patchwork Fri Jun 22 08:31:18 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 10481525 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id AB9F160388 for ; Fri, 22 Jun 2018 08:33:16 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9871A27B2F for ; Fri, 22 Jun 2018 08:33:16 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8BF0127F8F; Fri, 22 Jun 2018 08:33:16 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 0375E27B2F for ; Fri, 22 Jun 2018 08:33:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=BHz3Tm6HrKFRcxn3/NOrk13rRq07+O7c4UwbnzTJFsQ=; b=jPJR10L/LkBl/R3SWfoGDTVBhP 6v9u80/G+2h4qToF8pJhGmZwKriaFuxBnkLKirJ82ttgavvTfmBT+oiPXIx5PI/9I3+DPb8V86fLh MBH2QcN+ZxpO5wtjs2TVidkRXRsNfGcYA9WxqkLdh7bE8oxcuy4w0RWaxYSZ71b0pwYdYRz1TlLtY enQ00L6AIZv+DBz1d1MIj4cvAHMHhyTbcgsQ66OXW5y8s3Zoha7lxwqOWhozA0gY9Rd+TXTeIII/f ILmQ0fZ78VfAk7F6YNtg9KXNfxBxuf5q7RKX5ohh1+uUYHOmCwVUMeryxbIU7ctuEgJD2pRRv+6Ig uGsVwb/w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fWHV8-00009G-RT; Fri, 22 Jun 2018 08:33:02 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fWHT5-0007OU-1A for linux-arm-kernel@lists.infradead.org; Fri, 22 Jun 2018 08:30:59 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A0733164F; Fri, 22 Jun 2018 01:30:44 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 722DC3F58F; Fri, 22 Jun 2018 01:30:44 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id C98801AE37BD; Fri, 22 Jun 2018 09:31:20 +0100 (BST) From: Will Deacon To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 4/4] arm64: insn: Don't fallback on nosync path for general insn patching Date: Fri, 22 Jun 2018 09:31:18 +0100 Message-Id: <1529656278-878-5-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1529656278-878-1-git-send-email-will.deacon@arm.com> References: <1529656278-878-1-git-send-email-will.deacon@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180622_013055_132862_18ADEC98 X-CRM114-Status: GOOD ( 15.45 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, rokhanna@nvidia.com, steve.capper@arm.com, catalin.marinas@arm.com, Will Deacon , leif.lindholm@linaro.org, avanbrunt@nvidia.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Patching kernel instructions at runtime requires other CPUs to undergo a context synchronisation event via an explicit ISB or an IPI in order to ensure that the new instructions are visible. This is required even for "hotpatch" instructions such as NOP and BL, so avoid optimising in this case and always go via stop_machine() when performing general patching. ftrace isn't quite as strict, so it can continue to call the nosync code directly. Signed-off-by: Will Deacon --- arch/arm64/include/asm/insn.h | 2 -- arch/arm64/kernel/insn.c | 56 +------------------------------------------ 2 files changed, 1 insertion(+), 57 deletions(-) diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h index f62c56b1793f..c6802dea6cab 100644 --- a/arch/arm64/include/asm/insn.h +++ b/arch/arm64/include/asm/insn.h @@ -446,8 +446,6 @@ u32 aarch64_insn_gen_prefetch(enum aarch64_insn_register base, s32 aarch64_get_branch_offset(u32 insn); u32 aarch64_set_branch_offset(u32 insn, s32 offset); -bool aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn); - int aarch64_insn_patch_text_nosync(void *addr, u32 insn); int aarch64_insn_patch_text(void *addrs[], u32 insns[], int cnt); diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c index 0f6a2e0cfde0..2b3413549734 100644 --- a/arch/arm64/kernel/insn.c +++ b/arch/arm64/kernel/insn.c @@ -149,20 +149,6 @@ int __kprobes aarch64_insn_write(void *addr, u32 insn) return __aarch64_insn_write(addr, cpu_to_le32(insn)); } -static bool __kprobes __aarch64_insn_hotpatch_safe(u32 insn) -{ - if (aarch64_get_insn_class(insn) != AARCH64_INSN_CLS_BR_SYS) - return false; - - return aarch64_insn_is_b(insn) || - aarch64_insn_is_bl(insn) || - aarch64_insn_is_svc(insn) || - aarch64_insn_is_hvc(insn) || - aarch64_insn_is_smc(insn) || - aarch64_insn_is_brk(insn) || - aarch64_insn_is_nop(insn); -} - bool __kprobes aarch64_insn_uses_literal(u32 insn) { /* ldr/ldrsw (literal), prfm */ @@ -189,22 +175,6 @@ bool __kprobes aarch64_insn_is_branch(u32 insn) aarch64_insn_is_bcond(insn); } -/* - * ARM Architecture Reference Manual for ARMv8 Profile-A, Issue A.a - * Section B2.6.5 "Concurrent modification and execution of instructions": - * Concurrent modification and execution of instructions can lead to the - * resulting instruction performing any behavior that can be achieved by - * executing any sequence of instructions that can be executed from the - * same Exception level, except where the instruction before modification - * and the instruction after modification is a B, BL, NOP, BKPT, SVC, HVC, - * or SMC instruction. - */ -bool __kprobes aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn) -{ - return __aarch64_insn_hotpatch_safe(old_insn) && - __aarch64_insn_hotpatch_safe(new_insn); -} - int __kprobes aarch64_insn_patch_text_nosync(void *addr, u32 insn) { u32 *tp = addr; @@ -239,11 +209,6 @@ static int __kprobes aarch64_insn_patch_text_cb(void *arg) for (i = 0; ret == 0 && i < pp->insn_cnt; i++) ret = aarch64_insn_patch_text_nosync(pp->text_addrs[i], pp->new_insns[i]); - /* - * aarch64_insn_patch_text_nosync() calls flush_icache_range(), - * which ends with "dsb; isb" pair guaranteeing global - * visibility. - */ /* Notify other processors with an additional increment. */ atomic_inc(&pp->cpu_count); } else { @@ -255,8 +220,7 @@ static int __kprobes aarch64_insn_patch_text_cb(void *arg) return ret; } -static -int __kprobes aarch64_insn_patch_text_sync(void *addrs[], u32 insns[], int cnt) +int __kprobes aarch64_insn_patch_text(void *addrs[], u32 insns[], int cnt) { struct aarch64_insn_patch patch = { .text_addrs = addrs, @@ -272,24 +236,6 @@ int __kprobes aarch64_insn_patch_text_sync(void *addrs[], u32 insns[], int cnt) cpu_online_mask); } -int __kprobes aarch64_insn_patch_text(void *addrs[], u32 insns[], int cnt) -{ - int ret; - u32 insn; - - /* Unsafe to patch multiple instructions without synchronizaiton */ - if (cnt == 1) { - ret = aarch64_insn_read(addrs[0], &insn); - if (ret) - return ret; - - if (aarch64_insn_hotpatch_safe(insn, insns[0])) - return aarch64_insn_patch_text_nosync(addrs[0], insns[0]); - } - - return aarch64_insn_patch_text_sync(addrs, insns, cnt); -} - static int __kprobes aarch64_get_imm_shift_mask(enum aarch64_insn_imm_type type, u32 *maskp, int *shiftp) {