From patchwork Mon Jun 15 19:07:08 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Long X-Patchwork-Id: 6611921 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 521DCC0020 for ; Mon, 15 Jun 2015 19:12:13 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 65F362077C for ; Mon, 15 Jun 2015 19:12:12 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CA3A220776 for ; Mon, 15 Jun 2015 19:12:10 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Z4ZlN-0006z6-8t; Mon, 15 Jun 2015 19:09:41 +0000 Received: from mail-qc0-f178.google.com ([209.85.216.178]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Z4ZjQ-0005bD-3d for linux-arm-kernel@lists.infradead.org; Mon, 15 Jun 2015 19:07:43 +0000 Received: by qcbfz6 with SMTP id fz6so7800798qcb.0 for ; Mon, 15 Jun 2015 12:07:18 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=j8G82t13DU9J8FDFpcRkmebdDxvaU9By3rH/0i+DqeE=; b=jkyeNITSTgIYqpl6Gewo6tsikBKW+rGLxQCa0Gwk7bk7GJlr9dUw1A3pG7v06u27OF p539cd2nl2AGMxOKV7mbsnqfHa2lHa1QixKXShb2iIoA+RqAU1sSZBRHUIK/eDVE2x8t LrjkuIS3OoHRBeCLyQuO5ZBD00Gj1UOeOVMQhQ9JWKaMDQg+C0o+4twIGX0noWbvNlnC z0bHnoUrsHL9wOmTJL29ZzlZF2TSDyjoTEGvYomFuHaOhO3D0XI+6Ns9SgA82teIGaKN 6flYfydVfdVInyF172ONFKxqR23pMlLQ9B+TIeNekNYqG0Qg9AGy3+JEbMmYSUHAhVvm zKWw== X-Gm-Message-State: ALoCoQnJJMsp8eZNvFcs3V0lGuNIVUpz83/2wFEGc2/rcWYFACNoTMEuTZLfOXELRdXwtol3Dd4g X-Received: by 10.140.83.168 with SMTP id j37mr37305568qgd.18.1434395238531; Mon, 15 Jun 2015 12:07:18 -0700 (PDT) Received: from localhost.localdomain (pool-72-71-243-249.cncdnh.fast00.myfairpoint.net. [72.71.243.249]) by mx.google.com with ESMTPSA id 6sm6748404qks.37.2015.06.15.12.07.17 (version=TLSv1.1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 15 Jun 2015 12:07:17 -0700 (PDT) From: David Long To: Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, Russell King Subject: [PATCH v7 6/7] arm64: Add kernel return probes support (kretprobes) Date: Mon, 15 Jun 2015 15:07:08 -0400 Message-Id: <1434395229-6654-7-git-send-email-dave.long@linaro.org> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1434395229-6654-1-git-send-email-dave.long@linaro.org> References: <1434395229-6654-1-git-send-email-dave.long@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150615_120740_307328_0CF9ECF7 X-CRM114-Status: GOOD ( 19.59 ) X-Spam-Score: -0.7 (/) Cc: "Jon Medhurst \(Tixy\)" , Steve Capper , Ananth N Mavinakayanahalli , linux-kernel@vger.kernel.org, Anil S Keshavamurthy , Masami Hiramatsu , Mark Brown , sandeepa.s.prabhu@gmail.com, William Cohen , davem@davemloft.net X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.7 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Sandeepa Prabhu The pre-handler of this special 'trampoline' kprobe executes the return probe handler functions and restores original return address in ELR_EL1. This way the saved pt_regs still hold the original register context to be carried back to the probed kernel function. Signed-off-by: Sandeepa Prabhu Signed-off-by: David A. Long --- arch/arm64/Kconfig | 1 + arch/arm64/kernel/kprobes.c | 75 ++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 75 insertions(+), 1 deletion(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 45a9bd81..5312be5 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -72,6 +72,7 @@ config ARM64 select HAVE_RCU_TABLE_FREE select HAVE_SYSCALL_TRACEPOINTS select HAVE_KPROBES + select HAVE_KRETPROBES if HAVE_KPROBES select IRQ_DOMAIN select MODULES_USE_ELF_RELA select NO_BOOTMEM diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c index 570218c..7e34ef3 100644 --- a/arch/arm64/kernel/kprobes.c +++ b/arch/arm64/kernel/kprobes.c @@ -583,7 +583,80 @@ static void __used __kprobes kretprobe_trampoline_holder(void) static void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) { - return (void *) 0; + struct kretprobe_instance *ri = NULL; + struct hlist_head *head, empty_rp; + struct hlist_node *tmp; + unsigned long flags, orig_ret_addr = 0; + unsigned long trampoline_address = + (unsigned long)&kretprobe_trampoline; + + INIT_HLIST_HEAD(&empty_rp); + kretprobe_hash_lock(current, &head, &flags); + + /* + * It is possible to have multiple instances associated with a given + * task either because multiple functions in the call path have + * a return probe installed on them, and/or more than one return + * probe was registered for a target function. + * + * We can handle this because: + * - instances are always inserted at the head of the list + * - when multiple return probes are registered for the same + * function, the first instance's ret_addr will point to the + * real return address, and all the rest will point to + * kretprobe_trampoline + */ + hlist_for_each_entry_safe(ri, tmp, head, hlist) { + if (ri->task != current) + /* another task is sharing our hash bucket */ + continue; + + if (ri->rp && ri->rp->handler) { + __this_cpu_write(current_kprobe, &ri->rp->kp); + get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; + ri->rp->handler(ri, regs); + __this_cpu_write(current_kprobe, NULL); + } + + orig_ret_addr = (unsigned long)ri->ret_addr; + recycle_rp_inst(ri, &empty_rp); + + if (orig_ret_addr != trampoline_address) + /* + * This is the real return address. Any other + * instances associated with this task are for + * other calls deeper on the call stack + */ + break; + } + + kretprobe_assert(ri, orig_ret_addr, trampoline_address); + /* restore the original return address */ + instruction_pointer(regs) = orig_ret_addr; + reset_current_kprobe(); + kretprobe_hash_unlock(current, &flags); + + hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { + hlist_del(&ri->hlist); + kfree(ri); + } + + /* return 1 so that post handlers not called */ + return (void *) orig_ret_addr; +} + +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, + struct pt_regs *regs) +{ + ri->ret_addr = (kprobe_opcode_t *)regs->regs[30]; + + /* replace return addr (x30) with trampoline */ + regs->regs[30] = (long)&kretprobe_trampoline; +} + +int __kprobes arch_trampoline_kprobe(struct kprobe *p) +{ + return 0; } int __init arch_init_kprobes(void)