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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 05198C433FE for ; Wed, 13 Oct 2021 08:14:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE1A36103C for ; Wed, 13 Oct 2021 08:14:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238808AbhJMIQ2 (ORCPT ); Wed, 13 Oct 2021 04:16:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:50766 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229830AbhJMIQY (ORCPT ); Wed, 13 Oct 2021 04:16:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E316860FDA; Wed, 13 Oct 2021 08:14:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1634112861; bh=NykAuL4Zs+K1r0m5ec470r276RbfqkZyRxE5hp85tts=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YDJuvWzO9Q9VVshMROzj0M+J3PvfMSu2V4Hj8rvk2A9SEnSRwGQQ0i7Ai54KcpYtZ TKZVNl9ExEhZUZ5lfMGfVCLhn36epSWvd+oYvYY21GY/N6kEPaOmhs1x6CIXh3aRks x+ipkpeNICeDerkzU3iAcnrQ0M+tWN7Nj/JCzyF1s1A0ByUPmqFaHPjaFF+sWuwnnW Y3CB7VIttO78gYaUbRRxdAW4zBIPeYPgAWse/pk67jNEHGFQyxnq5cqRNs6mzHUBi9 G/Cgf2BD8KHKoJyKJB9LC3JA7Osp7adEErhC3ufinnGfjLopagms8bsyej3iSqoo82 t3HZR+tIBOv0Q== Date: Wed, 13 Oct 2021 09:14:16 +0100 From: Will Deacon To: Masami Hiramatsu Cc: Steven Rostedt , "Naveen N . Rao" , Ananth N Mavinakayanahalli , Ingo Molnar , linux-kernel@vger.kernel.org, Sven Schnelle , Catalin Marinas , Russell King , Nathan Chancellor , Nick Desaulniers , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 5/8] arm64: Recover kretprobe modified return address in stacktrace Message-ID: <20211013081416.GC6701@willie-the-truck> References: <163369609308.636038.15295764725220907794.stgit@devnote2> <163369613866.636038.15240679956943005288.stgit@devnote2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <163369613866.636038.15240679956943005288.stgit@devnote2> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 08, 2021 at 09:28:58PM +0900, Masami Hiramatsu wrote: > Since the kretprobe replaces the function return address with > the kretprobe_trampoline on the stack, stack unwinder shows it > instead of the correct return address. > > This checks whether the next return address is the > __kretprobe_trampoline(), and if so, try to find the correct > return address from the kretprobe instance list. > > With this fix, now arm64 can enable > CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE, and pass the > kprobe self tests. > > Signed-off-by: Masami Hiramatsu > --- > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/stacktrace.h | 2 ++ > arch/arm64/kernel/stacktrace.c | 3 +++ > 3 files changed, 6 insertions(+) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 5c7ae4c3954b..edde5171ffb2 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -11,6 +11,7 @@ config ARM64 > select ACPI_PPTT if ACPI > select ARCH_HAS_DEBUG_WX > select ARCH_BINFMT_ELF_STATE > + select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE > select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION > select ARCH_ENABLE_MEMORY_HOTPLUG > select ARCH_ENABLE_MEMORY_HOTREMOVE > diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h > index 8aebc00c1718..8f997a602651 100644 > --- a/arch/arm64/include/asm/stacktrace.h > +++ b/arch/arm64/include/asm/stacktrace.h > @@ -9,6 +9,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -59,6 +60,7 @@ struct stackframe { > #ifdef CONFIG_FUNCTION_GRAPH_TRACER > int graph; > #endif > + struct llist_node *kr_cur; > }; Please update the comment above this structure to describe the new member you're adding. If it's only relevant for kprobes, then let's define it conditionally too (based on CONFIG_KRETPROBES ?) > extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame); > diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c > index 8982a2b78acf..f1eef5745542 100644 > --- a/arch/arm64/kernel/stacktrace.c > +++ b/arch/arm64/kernel/stacktrace.c > @@ -129,6 +129,8 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) > frame->pc = ret_stack->ret; > } > #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ > + if (is_kretprobe_trampoline(frame->pc)) > + frame->pc = kretprobe_find_ret_addr(tsk, (void *)frame->fp, &frame->kr_cur); > > frame->pc = ptrauth_strip_insn_pac(frame->pc); > > @@ -224,6 +226,7 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, > { > struct stackframe frame; > > + memset(&frame, 0, sizeof(frame)); Why do we need this? Will