From patchwork Tue Aug 11 00:52:43 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Long X-Patchwork-Id: 52276 Return-Path: X-Original-To: linaro@patches.linaro.org Delivered-To: linaro@patches.linaro.org Received: from mail-wi0-f197.google.com (mail-wi0-f197.google.com [209.85.212.197]) by patches.linaro.org (Postfix) with ESMTPS id 7E8D12152A for ; Tue, 11 Aug 2015 00:53:06 +0000 (UTC) Received: by wijp15 with SMTP id p15sf43846396wij.3 for ; Mon, 10 Aug 2015 17:53:05 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:delivered-to:from:to:cc:subject :date:message-id:in-reply-to:references:x-original-sender :x-original-authentication-results:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-unsubscribe; bh=ZPUqMrlgLo8GnvhGYDZ4D+7ncCIx4KzeXrsYbifUveA=; b=T98kKlcp/yzzMAaU+3BLeIsl1Tzk7arCcszuyGxqr5rWAdQ6ruFl6Kemf3fs3z2R94 Ky3gsiGiIOghUPpE1xkCj/mevl15YyLgr87N3joajyGWR38BvoTp5hTQC2vK9UmHzDhx PLg78IjbEptNfZWCIkRbUIiVapMCxejgJydXBTMDkFCIXMGk2iR6VpHz/HQe+pi8ktSK g487qytax5/r7Jxl+mBG5BaYNFNRQszN7NE4sBb+7Knp4EeDtAqTTl+HNw8vh11f4khs cSdrXSv+6qmWJCIO81KvRiTCh2NU4uMDFJZ19ZKP4KEAbQSs+Mb2Gs8l7onw6DlfcsKx Xh3Q== X-Gm-Message-State: ALoCoQnJu0HeggJeOIMJDw+o5pCSdT0khfGf9NGYb6o4AxyKCkSVJZlvDBR82IRP4NI/C5/RVt6R X-Received: by 10.180.75.49 with SMTP id z17mr4510963wiv.7.1439254385865; Mon, 10 Aug 2015 17:53:05 -0700 (PDT) MIME-Version: 1.0 X-BeenThere: patchwork-forward@linaro.org Received: by 10.152.21.3 with SMTP id r3ls892313lae.89.gmail; Mon, 10 Aug 2015 17:53:05 -0700 (PDT) X-Received: by 10.152.44.196 with SMTP id g4mr5118956lam.56.1439254385693; Mon, 10 Aug 2015 17:53:05 -0700 (PDT) Received: from mail-la0-f52.google.com (mail-la0-f52.google.com. [209.85.215.52]) by mx.google.com with ESMTPS id kx19si26867lbb.32.2015.08.10.17.53.05 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 10 Aug 2015 17:53:05 -0700 (PDT) Received-SPF: pass (google.com: domain of patch+caf_=patchwork-forward=linaro.org@linaro.org designates 209.85.215.52 as permitted sender) client-ip=209.85.215.52; Received: by lahi9 with SMTP id i9so32231340lah.2 for ; Mon, 10 Aug 2015 17:53:05 -0700 (PDT) X-Received: by 10.112.176.228 with SMTP id cl4mr23649053lbc.106.1439254385566; Mon, 10 Aug 2015 17:53:05 -0700 (PDT) X-Forwarded-To: patchwork-forward@linaro.org X-Forwarded-For: patch@linaro.org patchwork-forward@linaro.org Delivered-To: patches@linaro.org Received: by 10.112.7.198 with SMTP id l6csp2215539lba; Mon, 10 Aug 2015 17:53:04 -0700 (PDT) X-Received: by 10.140.93.103 with SMTP id c94mr19875127qge.54.1439254374156; Mon, 10 Aug 2015 17:52:54 -0700 (PDT) Received: from mail-qg0-f42.google.com (mail-qg0-f42.google.com. [209.85.192.42]) by mx.google.com with ESMTPS id b41si29297qkh.99.2015.08.10.17.52.53 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 10 Aug 2015 17:52:54 -0700 (PDT) Received-SPF: pass (google.com: domain of dave.long@linaro.org designates 209.85.192.42 as permitted sender) client-ip=209.85.192.42; Received: by qgj62 with SMTP id 62so104828816qgj.2 for ; Mon, 10 Aug 2015 17:52:53 -0700 (PDT) X-Received: by 10.140.30.118 with SMTP id c109mr16212252qgc.37.1439254373436; Mon, 10 Aug 2015 17:52:53 -0700 (PDT) Received: from localhost.localdomain (pool-72-71-243-249.cncdnh.fast00.myfairpoint.net. [72.71.243.249]) by smtp.googlemail.com with ESMTPSA id m62sm167234qhb.45.2015.08.10.17.52.52 (version=TLSv1.1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 10 Aug 2015 17:52:53 -0700 (PDT) From: David Long To: Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, Russell King Cc: sandeepa.s.prabhu@gmail.com, William Cohen , Steve Capper , "Jon Medhurst (Tixy)" , Masami Hiramatsu , Ananth N Mavinakayanahalli , Anil S Keshavamurthy , , Mark Brown , linux-kernel@vger.kernel.org Subject: [PATCH v8 6/7] arm64: Add kernel return probes support (kretprobes) Date: Mon, 10 Aug 2015 20:52:43 -0400 Message-Id: <1439254364-15362-7-git-send-email-dave.long@linaro.org> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1439254364-15362-1-git-send-email-dave.long@linaro.org> References: <1439254364-15362-1-git-send-email-dave.long@linaro.org> X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: dave.long@linaro.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of patch+caf_=patchwork-forward=linaro.org@linaro.org designates 209.85.215.52 as permitted sender) smtp.mailfrom=patch+caf_=patchwork-forward=linaro.org@linaro.org Precedence: list Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org List-ID: X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , 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 1bb07f7..9a589a6 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -74,6 +74,7 @@ config ARM64 select HAVE_RCU_TABLE_FREE select HAVE_SYSCALL_TRACEPOINTS select HAVE_KPROBES + select HAVE_KRETPROBES if HAVE_KPROBES select IRQ_DOMAIN select IRQ_FORCED_THREADING select MODULES_USE_ELF_RELA diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c index 98db85c..1dadad8 100644 --- a/arch/arm64/kernel/kprobes.c +++ b/arch/arm64/kernel/kprobes.c @@ -562,7 +562,80 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) 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)