From patchwork Fri Apr 5 12:40:45 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 10887337 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 739E615AC for ; Fri, 5 Apr 2019 12:42:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 59E1C28B67 for ; Fri, 5 Apr 2019 12:42:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 583EB28B72; Fri, 5 Apr 2019 12:42:09 +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=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED 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 CC35F28B67 for ; Fri, 5 Apr 2019 12:42:08 +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=kuzVbmIM3URnn+WHeBI4jhe96W43F9wSNMSISRhFkas=; b=FKogbrsH6yhBTHyLkoI+1l6nuC wOEvpkucXxpYO9LRuXOTmWZorN+NVIVGVtAsxR7z6cd4RX1ncCvmJEwxogLHVqo76Alt37geNVwuf 4jAmoUWdsYWHA4pS82ZxzaHGMdhKz+fTY04rJw4bulaA9mR7F9K9fNlA8xsAL0Q9krhcA/hX9AVQc HVnBHTs6OOhRBTbMlMzNcLRDP9wEcDaA4Zyd3/el7vZUJEBZAHcpWmscorvtC0n88TRojIxkv63Zk BDgq+wSvGo1KWPgbi6XQvsgGSPIi5Zqc2FxiGAyXXcxGBVEIinpqUEr35F2n/iPw2aIgj3OPYzk9H lc20yMtQ==; 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 1hCOAU-0006AU-7v; Fri, 05 Apr 2019 12:42:02 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hCO9X-00050a-7G for linux-arm-kernel@lists.infradead.org; Fri, 05 Apr 2019 12:41:17 +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 51C551A25; Fri, 5 Apr 2019 05:40:58 -0700 (PDT) Received: from fuggles.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 88E643F557; Fri, 5 Apr 2019 05:40:57 -0700 (PDT) From: Will Deacon To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 5/8] arm64: kprobes: Avoid calling kprobes debug handlers explicitly Date: Fri, 5 Apr 2019 13:40:45 +0100 Message-Id: <20190405124048.3287-6-will.deacon@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190405124048.3287-1-will.deacon@arm.com> References: <20190405124048.3287-1-will.deacon@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190405_054103_682509_438DC566 X-CRM114-Status: GOOD ( 14.56 ) 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, Will Deacon 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 Kprobes bypasses our debug hook registration code so that it doesn't get tangled up with recursive debug exceptions from things like lockdep: http://lists.infradead.org/pipermail/linux-arm-kernel/2015-February/324385.html However, since then, (a) the hook list has become RCU protected and (b) the kprobes hooks were found not to filter out exceptions from userspace correctly. On top of that, the step handler is invoked directly from single_step_handler(), which *does* use the debug hook list, so it's clearly not the end of the world. For now, have kprobes use the debug hook registration API like everybody else. We can revisit this in the future if this is found to limit coverage significantly. Reviewed-by: Mark Rutland Signed-off-by: Will Deacon --- arch/arm64/include/asm/kprobes.h | 2 -- arch/arm64/kernel/debug-monitors.c | 10 ---------- arch/arm64/kernel/probes/kprobes.c | 16 ++++++++++++++-- 3 files changed, 14 insertions(+), 14 deletions(-) diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h index d5a44cf859e9..21721fbf44e7 100644 --- a/arch/arm64/include/asm/kprobes.h +++ b/arch/arm64/include/asm/kprobes.h @@ -54,8 +54,6 @@ void arch_remove_kprobe(struct kprobe *); int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr); int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data); -int kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr); -int kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr); void kretprobe_trampoline(void); void __kprobes *trampoline_probe_handler(struct pt_regs *regs); diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index 9b3fd7fa5b43..f4d8cda8830d 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -258,10 +258,6 @@ static int single_step_handler(unsigned long unused, unsigned int esr, if (!reinstall_suspended_bps(regs)) return 0; -#ifdef CONFIG_KPROBES - if (kprobe_single_step_handler(regs, esr) == DBG_HOOK_HANDLED) - handler_found = true; -#endif if (!handler_found && call_step_hook(regs, esr) == DBG_HOOK_HANDLED) handler_found = true; @@ -337,12 +333,6 @@ static int brk_handler(unsigned long unused, unsigned int esr, { bool handler_found = false; -#ifdef CONFIG_KPROBES - if ((esr & BRK64_ESR_MASK) == BRK64_ESR_KPROBES) { - if (kprobe_breakpoint_handler(regs, esr) == DBG_HOOK_HANDLED) - handler_found = true; - } -#endif if (!handler_found && call_break_hook(regs, esr) == DBG_HOOK_HANDLED) handler_found = true; diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index 7a679caf4585..baf97f47aec0 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -439,7 +439,7 @@ kprobe_ss_hit(struct kprobe_ctlblk *kcb, unsigned long addr) return DBG_HOOK_ERROR; } -int __kprobes +static int __kprobes kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr) { struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); @@ -461,7 +461,11 @@ kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr) return retval; } -int __kprobes +static struct step_hook kprobes_step_hook = { + .fn = kprobe_single_step_handler, +}; + +static int __kprobes kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr) { if (user_mode(regs)) @@ -471,6 +475,11 @@ kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr) return DBG_HOOK_HANDLED; } +static struct break_hook kprobes_break_hook = { + .imm = BRK64_ESR_KPROBES, + .fn = kprobe_breakpoint_handler, +}; + /* * Provide a blacklist of symbols identifying ranges which cannot be kprobed. * This blacklist is exposed to userspace via debugfs (kprobes/blacklist). @@ -599,5 +608,8 @@ int __kprobes arch_trampoline_kprobe(struct kprobe *p) int __init arch_init_kprobes(void) { + register_kernel_break_hook(&kprobes_break_hook); + register_kernel_step_hook(&kprobes_step_hook); + return 0; }