From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8889C54E8B for ; Sun, 10 May 2020 08:59:48 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BEB49208E4 for ; Sun, 10 May 2020 08:59:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Wv/Yr+xb"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="HNsh0B/2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BEB49208E4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Mime-Version:References:In-Reply-To: Message-Id:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=FetQGybE+/Trwh1olRn4uZnn4rwyliolR5xT9TykoPw=; b=Wv/Yr+xb21OKPq 4ezJ87aKCQHw9ycQBOeJnj02Je2+Nhtl7w8woKicjGp0UHQnEZl6LKjQ8NPviJpe3yk+ylyjekLj6 IhFkJXo2amdn2ZKJDwvZkQmsUSny5LRZU2fhOl9z2BiJONwtc0DpT4uHt3dt9pkU+SxRI9nYHPaWD C4RIGee/s5N+TOsiWpVJhXr6oHlL5bpngoUrAkspNtZdF2TGI6/cYJ2617YNHPU2n7VVLyOmP0wM5 X3VsDmJiwGDGXJ3MK/G9pnbivfGoYYtxm07vY3PQaYnPjnb4odf78Ec2rM5GhRAUuNDdOX04gkjgc Ihma0Hkz7CKXx/EAfZjg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jXhoJ-0004uO-VY; Sun, 10 May 2020 08:59:47 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jXhoH-0004tk-6o for linux-arm-kernel@lists.infradead.org; Sun, 10 May 2020 08:59:46 +0000 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 367B9208DB; Sun, 10 May 2020 08:59:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589101183; bh=/RntUQgZ4VxLxMu4+YNoen/YFz9jHRYb9h2qimOY4zI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=HNsh0B/2fbkkfKqwDlJ6WNg6+tgtHSwmphr8OrRhTD986IKOz0KikcMko3h0lnP4s MDPvuIH6Rf2CCgePtqjqBoSxKU2KWPrB2fjWtrhElXZvIx6KQPnEc2Y20NKk6ej3gt tDgGgbrOx84K7Xr18Uif4Sgs9KTqTqOFCuD3uOgM= Date: Sun, 10 May 2020 17:59:38 +0900 From: Masami Hiramatsu To: Wei Li Subject: Re: [PATCH 2/4] arm64: Extract kprobes_save_local_irqflag() and kprobes_restore_local_irqflag() Message-Id: <20200510175938.7c888bd01f82d29203995c63@kernel.org> In-Reply-To: <20200509214159.19680-3-liwei391@huawei.com> References: <20200509214159.19680-1-liwei391@huawei.com> <20200509214159.19680-3-liwei391@huawei.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200510_015945_289303_6D3C1B03 X-CRM114-Status: GOOD ( 18.61 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, daniel.thompson@linaro.org, catalin.marinas@arm.com, maz@kernel.org, dianders@chromium.org, linux-kernel@vger.kernel.org, liwei1412@163.com, jason.wessel@windriver.com, will@kernel.org, davem@davemloft.net, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Wei, On Sun, 10 May 2020 05:41:57 +0800 Wei Li wrote: > PSTATE.I and PSTATE.D are very important for single-step working. > > Without disabling interrupt on local CPU, there is a chance of > interrupt occurrence in the period of exception return and start of > out-of-line single-step, that result in wrongly single stepping > into the interrupt handler. And if D bit is set then, it results into > undefined exception and when it's handler enables dbg then single-step > exception is generated, not as expected. > > As they are maintained well in kprobes_save_local_irqflag() and > kprobes_restore_local_irqflag() for kprobe module, extract them as > kernel_prepare_single_step() and kernel_cleanup_single_step() for > general use. Agreed, these prepare/cleanup should be generic. Reviewed-by: Masami Hiramatsu Thank you! > > Signed-off-by: Wei Li > --- > arch/arm64/include/asm/debug-monitors.h | 4 ++++ > arch/arm64/kernel/debug-monitors.c | 26 +++++++++++++++++++++++ > arch/arm64/kernel/probes/kprobes.c | 28 ++----------------------- > 3 files changed, 32 insertions(+), 26 deletions(-) > > diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h > index 7619f473155f..b62469f3475b 100644 > --- a/arch/arm64/include/asm/debug-monitors.h > +++ b/arch/arm64/include/asm/debug-monitors.h > @@ -113,6 +113,10 @@ void user_fastforward_single_step(struct task_struct *task); > void kernel_enable_single_step(struct pt_regs *regs); > void kernel_disable_single_step(void); > int kernel_active_single_step(void); > +void kernel_prepare_single_step(unsigned long *flags, > + struct pt_regs *regs); > +void kernel_cleanup_single_step(unsigned long flags, > + struct pt_regs *regs); > > #ifdef CONFIG_HAVE_HW_BREAKPOINT > int reinstall_suspended_bps(struct pt_regs *regs); > diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c > index 48222a4760c2..25ce6b5a52d2 100644 > --- a/arch/arm64/kernel/debug-monitors.c > +++ b/arch/arm64/kernel/debug-monitors.c > @@ -429,6 +429,32 @@ int kernel_active_single_step(void) > } > NOKPROBE_SYMBOL(kernel_active_single_step); > > +/* > + * Interrupts need to be disabled before single-step mode is set, and not > + * reenabled until after single-step mode ends. > + * Without disabling interrupt on local CPU, there is a chance of > + * interrupt occurrence in the period of exception return and start of > + * out-of-line single-step, that result in wrongly single stepping > + * into the interrupt handler. > + */ > +void kernel_prepare_single_step(unsigned long *flags, > + struct pt_regs *regs) > +{ > + *flags = regs->pstate & DAIF_MASK; > + regs->pstate |= PSR_I_BIT; > + /* Unmask PSTATE.D for enabling software step exceptions. */ > + regs->pstate &= ~PSR_D_BIT; > +} > +NOKPROBE_SYMBOL(kernel_prepare_single_step); > + > +void kernel_cleanup_single_step(unsigned long flags, > + struct pt_regs *regs) > +{ > + regs->pstate &= ~DAIF_MASK; > + regs->pstate |= flags; > +} > +NOKPROBE_SYMBOL(kernel_cleanup_single_step); > + > /* ptrace API */ > void user_enable_single_step(struct task_struct *task) > { > diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c > index d1c95dcf1d78..c655b6b543e3 100644 > --- a/arch/arm64/kernel/probes/kprobes.c > +++ b/arch/arm64/kernel/probes/kprobes.c > @@ -168,30 +168,6 @@ static void __kprobes set_current_kprobe(struct kprobe *p) > __this_cpu_write(current_kprobe, p); > } > > -/* > - * Interrupts need to be disabled before single-step mode is set, and not > - * reenabled until after single-step mode ends. > - * Without disabling interrupt on local CPU, there is a chance of > - * interrupt occurrence in the period of exception return and start of > - * out-of-line single-step, that result in wrongly single stepping > - * into the interrupt handler. > - */ > -static void __kprobes kprobes_save_local_irqflag(struct kprobe_ctlblk *kcb, > - struct pt_regs *regs) > -{ > - kcb->saved_irqflag = regs->pstate & DAIF_MASK; > - regs->pstate |= PSR_I_BIT; > - /* Unmask PSTATE.D for enabling software step exceptions. */ > - regs->pstate &= ~PSR_D_BIT; > -} > - > -static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb, > - struct pt_regs *regs) > -{ > - regs->pstate &= ~DAIF_MASK; > - regs->pstate |= kcb->saved_irqflag; > -} > - > static void __kprobes > set_ss_context(struct kprobe_ctlblk *kcb, unsigned long addr) > { > @@ -227,7 +203,7 @@ static void __kprobes setup_singlestep(struct kprobe *p, > set_ss_context(kcb, slot); /* mark pending ss */ > > /* IRQs and single stepping do not mix well. */ > - kprobes_save_local_irqflag(kcb, regs); > + kernel_prepare_single_step(&kcb->saved_irqflag, regs); > kernel_enable_single_step(regs); > instruction_pointer_set(regs, slot); > } else { > @@ -414,7 +390,7 @@ kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr) > retval = kprobe_ss_hit(kcb, instruction_pointer(regs)); > > if (retval == DBG_HOOK_HANDLED) { > - kprobes_restore_local_irqflag(kcb, regs); > + kernel_cleanup_single_step(kcb->saved_irqflag, regs); > kernel_disable_single_step(); > > post_kprobe_handler(kcb, regs); > -- > 2.17.1 > -- Masami Hiramatsu _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel