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=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 049F3C433E0 for ; Wed, 3 Feb 2021 01:55:36 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 B327D64F75 for ; Wed, 3 Feb 2021 01:55:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B327D64F75 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4DVlBX3nzZzDwk2 for ; Wed, 3 Feb 2021 12:55:32 +1100 (AEDT) Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4DVQ2L1tY3zDqRB for ; Wed, 3 Feb 2021 00:02:18 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=kqRY050g; dkim-atps=neutral Received: by ozlabs.org (Postfix) id 4DVQ2G00BBz9vFD; Wed, 3 Feb 2021 00:02:14 +1100 (AEDT) Received: by ozlabs.org (Postfix, from userid 1034) id 4DVQ2F4p7Gz9vFF; Wed, 3 Feb 2021 00:02:13 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1612270933; bh=Bx30iDFxYr5YeLlZWgnT3sSvAGju3qwUqafhouzOPtU=; h=From:To:Subject:Date:From; b=kqRY050gSbjvlWo4TKOiygR6v+pKo0laYo2EJnEC/3bNDhME8UvrSh7OVSlfH4xpL g41811wz+laMMYzQARV3Hnzlui6GC4bcJ3aORqoniWRxCA2sWseo7HcyVxoI1EKbJX FHqwz7gjySVvfQ16V244jbZr/7c3jQLtKnp1THdbF7Mi1PpcyPusmNXm5i6jpOy98O iIS8TZvchr631Br+Di2xWhrdiZGdx/O9mksXwf9ICzRHgxv8n5VROeLEaSVL7Mw98R 31hp9LwmkAZAJjD5UW0qvAwVWzcEqHbsML07lIAPCX7S2152H6wGDiVt8LvhmbDvQl oPY3r7YujDtlw== From: Michael Ellerman To: linuxppc-dev@ozlabs.org Subject: [PATCH 1/2] powerpc/64: Make stack tracing work during very early boot Date: Wed, 3 Feb 2021 00:02:06 +1100 Message-Id: <20210202130207.1303975-1-mpe@ellerman.id.au> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" If we try to stack trace very early during boot, either due to a WARN/BUG or manual dump_stack(), we will oops in valid_emergency_stack() when we try to dereference the paca_ptrs array. The fix is simple, we just return false if paca_ptrs isn't allocated yet. The stack pointer definitely isn't part of any emergency stack because we haven't allocated any yet. Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/process.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 8520ed5ae144..e296440e9d16 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -2047,6 +2047,9 @@ static inline int valid_emergency_stack(unsigned long sp, struct task_struct *p, unsigned long stack_page; unsigned long cpu = task_cpu(p); + if (!paca_ptrs) + return 0; + stack_page = (unsigned long)paca_ptrs[cpu]->emergency_sp - THREAD_SIZE; if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes) return 1; -- 2.25.1