From nobody Thu Sep 18 23:13:21 2025 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1E87CC4332F for ; Fri, 2 Dec 2022 02:18:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232025AbiLBCSr (ORCPT ); Thu, 1 Dec 2022 21:18:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231990AbiLBCSj (ORCPT ); Thu, 1 Dec 2022 21:18:39 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7715ECAF96 for ; Thu, 1 Dec 2022 18:18:38 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EE6C9621EF for ; Fri, 2 Dec 2022 02:18:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6393C433D6; Fri, 2 Dec 2022 02:18:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669947517; bh=d/lXGG0C2aiD02jOJY4ptnK9ZuIklkzqbOFkMk8yr0Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nIcOtysO/1w3lc+kLQuqC0ib2g7qPgkTgrCEhLuYzBJpk/gtzaibZPU4g2BgqOhRf mDc07gKkTVFokUSPi/PCJBp6rerTt+MmmmR1Cx8dUD/qfKSdvUOikLBrtp/R/VtQid fRv9cybKiXw4Nfgjbb9hVipdUBiWS2kdrTtUPPkqo4KQ6lNl+aTRmHxt3KqAPMk6jN Mplg13O9zyrFyUNYQI3JiAJgntKbbRH+gZqNO/pEIMOZYvZRzUg497vpeVCxsUYn7i pUhJDFtfRX/5/DgCW7aGnfvPeaYG4ECIwh41hqpPObpsFZDK56a+XEZn0ipoHUNd8D sWxn78mF86hdQ== From: "Masami Hiramatsu (Google)" To: Catalin Marinas , Will Deacon Cc: Mark Rutland , Mark Brown , Kalesh Singh , Masami Hiramatsu , Marc Zyngier , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sandeepa Prabhu Subject: [PATCH v2 1/3] arm64: Prohibit instrumentation on arch_stack_walk() Date: Fri, 2 Dec 2022 11:18:33 +0900 Message-Id: <166994751368.439920.3236636557520824664.stgit@devnote3> X-Mailer: git-send-email 2.39.0.rc0.267.gcb52ba06e7-goog In-Reply-To: <166994750386.439920.1754385804350980158.stgit@devnote3> References: <166994750386.439920.1754385804350980158.stgit@devnote3> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu (Google) Mark arch_stack_walk() as noinstr instead of notrace and inline functions called from arch_stack_walk() as __always_inline so that user does not put any instrumentations on it, because this function can be used from return_address() which is used by lockdep. Without this, if the kernel built with CONFIG_LOCKDEP=3Dy, just probing arch_stack_walk() via /kprobe_events will crash the kernel on arm64. # echo p arch_stack_walk >> ${TRACEFS}/kprobe_events # echo 1 > ${TRACEFS}/events/kprobes/enable kprobes: Failed to recover from reentered kprobes. kprobes: Dump kprobe: .symbol_name =3D arch_stack_walk, .offset =3D 0, .addr =3D arch_stack_wal= k+0x0/0x1c0 ------------[ cut here ]------------ kernel BUG at arch/arm64/kernel/probes/kprobes.c:241! kprobes: Failed to recover from reentered kprobes. kprobes: Dump kprobe: .symbol_name =3D arch_stack_walk, .offset =3D 0, .addr =3D arch_stack_wal= k+0x0/0x1c0 ------------[ cut here ]------------ kernel BUG at arch/arm64/kernel/probes/kprobes.c:241! PREEMPT SMP Modules linked in: CPU: 0 PID: 17 Comm: migration/0 Tainted: G N 6.1.0-rc5+ = #6 Hardware name: linux,dummy-virt (DT) Stopper: 0x0 <- 0x0 pstate: 600003c5 (nZCv DAIF -PAN -UAO -TCO -DIT -SSBS BTYPE=3D--) pc : kprobe_breakpoint_handler+0x178/0x17c lr : kprobe_breakpoint_handler+0x178/0x17c sp : ffff8000080d3090 x29: ffff8000080d3090 x28: ffff0df5845798c0 x27: ffffc4f59057a774 x26: ffff0df5ffbba770 x25: ffff0df58f420f18 x24: ffff49006f641000 x23: ffffc4f590579768 x22: ffff0df58f420f18 x21: ffff8000080d31c0 x20: ffffc4f590579768 x19: ffffc4f590579770 x18: 0000000000000006 x17: 5f6b636174735f68 x16: 637261203d207264 x15: 64612e202c30203d x14: 2074657366666f2e x13: 30633178302f3078 x12: 302b6b6c61775f6b x11: 636174735f686372 x10: ffffc4f590dc5bd8 x9 : ffffc4f58eb31958 x8 : 00000000ffffefff x7 : ffffc4f590dc5bd8 x6 : 80000000fffff000 x5 : 000000000000bff4 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000000 x1 : ffff0df5845798c0 x0 : 0000000000000064 Call trace: kprobes: Failed to recover from reentered kprobes. kprobes: Dump kprobe: .symbol_name =3D arch_stack_walk, .offset =3D 0, .addr =3D arch_stack_wal= k+0x0/0x1c0 ------------[ cut here ]------------ kernel BUG at arch/arm64/kernel/probes/kprobes.c:241! Fixes: 39ef362d2d45 ("arm64: Make return_address() use arch_stack_walk()") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) Acked-by: Mark Rutland --- Changes in v2: - Use noinstr instead of NOKPROBE_SYMBOL() - Use __always_inline because nokprobe_inline will be changed if CONFIG_KPROBES=3Dn. - Fix indentation. --- arch/arm64/kernel/stacktrace.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 634279b3b03d..117e2c180f3c 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -23,8 +23,8 @@ * * The regs must be on a stack currently owned by the calling task. */ -static inline void unwind_init_from_regs(struct unwind_state *state, - struct pt_regs *regs) +static __always_inline void unwind_init_from_regs(struct unwind_state *sta= te, + struct pt_regs *regs) { unwind_init_common(state, current); =20 @@ -58,8 +58,8 @@ static __always_inline void unwind_init_from_caller(struc= t unwind_state *state) * duration of the unwind, or the unwind will be bogus. It is never valid = to * call this for the current task. */ -static inline void unwind_init_from_task(struct unwind_state *state, - struct task_struct *task) +static __always_inline void unwind_init_from_task(struct unwind_state *sta= te, + struct task_struct *task) { unwind_init_common(state, task); =20 @@ -186,7 +186,7 @@ void show_stack(struct task_struct *tsk, unsigned long = *sp, const char *loglvl) : stackinfo_get_unknown(); \ }) =20 -noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, +noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, struct task_struct *task, struct pt_regs *regs) {