From patchwork Tue Feb 15 18:31:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 1593206 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=2404:9400:2:0:216:3eff:fee1:b9f1; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org; receiver=) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2404:9400:2:0:216:3eff:fee1:b9f1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by bilbo.ozlabs.org (Postfix) with ESMTPS id 4JyqTQ6mv0z9sCD for ; Wed, 16 Feb 2022 05:32:58 +1100 (AEDT) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4JyqTQ3TlBz3cYp for ; Wed, 16 Feb 2022 05:32:58 +1100 (AEDT) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=csgroup.eu (client-ip=93.17.235.10; helo=pegase2.c-s.fr; envelope-from=christophe.leroy@csgroup.eu; receiver=) Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4JyqST515Mz3cCG for ; Wed, 16 Feb 2022 05:32:09 +1100 (AEDT) Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4JyqSD4Khxz9sS9; Tue, 15 Feb 2022 19:31:56 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8ypNzNVQ374H; Tue, 15 Feb 2022 19:31:56 +0100 (CET) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4JyqSB1WCKz9sSB; Tue, 15 Feb 2022 19:31:54 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 124AC8B77B; Tue, 15 Feb 2022 19:31:54 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id p6EysXEEycC9; Tue, 15 Feb 2022 19:31:53 +0100 (CET) Received: from PO20335.IDSI0.si.c-s.fr (unknown [192.168.6.174]) by messagerie.si.c-s.fr (Postfix) with ESMTP id BEE268B779; Tue, 15 Feb 2022 19:31:53 +0100 (CET) Received: from PO20335.IDSI0.si.c-s.fr (localhost [127.0.0.1]) by PO20335.IDSI0.si.c-s.fr (8.17.1/8.16.1) with ESMTPS id 21FIViqR146776 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Tue, 15 Feb 2022 19:31:44 +0100 Received: (from chleroy@localhost) by PO20335.IDSI0.si.c-s.fr (8.17.1/8.17.1/Submit) id 21FIVijG146775; Tue, 15 Feb 2022 19:31:44 +0100 X-Authentication-Warning: PO20335.IDSI0.si.c-s.fr: chleroy set sender to christophe.leroy@csgroup.eu using -f From: Christophe Leroy To: Steven Rostedt , Ingo Molnar , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Subject: [PATCH v1 3/4] powerpc/ftrace: Have arch_ftrace_get_regs() return NULL unless FL_SAVE_REGS is set Date: Tue, 15 Feb 2022 19:31:24 +0100 Message-Id: <2f9a7e898c93cc7438ef5ccd47cb9c3a9c5b53ef.1644949750.git.christophe.leroy@csgroup.eu> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1644949837; l=1733; s=20211009; h=from:subject:message-id; bh=cAWvlwCa+nEKIutuhyeNrkOt9aAuzzmtgF3bPEJq5WY=; b=b07RY3tcCjuMLFy7nTaDe7Z4KjEYo6N6K86nUQyejxDiLo0SVJ2huhqZmQGwbQzw5+lFz7MY26rx gpN8vPayC0jqRosi3GwRiBDBGu1g6JPW7fH1WqZoQrIyf2CDX7+N X-Developer-Key: i=christophe.leroy@csgroup.eu; a=ed25519; pk=HIzTzUj91asvincQGOFx6+ZF5AoUuP9GdOtQChs7Mm0= 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: , Cc: "Naveen N . Rao" , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" When FL_SAVE_REGS is not set we get here via ftrace_caller() which doesn't save all registers. ftrace_caller() explicitely clears regs.msr, so we can rely on it to know where we come from. We don't expect MSR register to be 0 at all when involving ftrace. Reported-by: Naveen N. Rao Fixes: 40b035efe288 ("powerpc/ftrace: Implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS") Signed-off-by: Christophe Leroy --- arch/powerpc/include/asm/ftrace.h | 3 ++- arch/powerpc/kernel/trace/ftrace_mprofile.S | 4 ++++ 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 70b457097098..ff034ae4e472 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -30,7 +30,8 @@ struct ftrace_regs { static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *fregs) { - return &fregs->regs; + /* We clear regs.msr in ftrace_call */ + return fregs->regs.msr ? &fregs->regs : NULL; } static __always_inline void ftrace_instruction_pointer_set(struct ftrace_regs *fregs, diff --git a/arch/powerpc/kernel/trace/ftrace_mprofile.S b/arch/powerpc/kernel/trace/ftrace_mprofile.S index 8443902d5a05..eb077270ec2f 100644 --- a/arch/powerpc/kernel/trace/ftrace_mprofile.S +++ b/arch/powerpc/kernel/trace/ftrace_mprofile.S @@ -205,6 +205,10 @@ _GLOBAL(ftrace_caller) PPC_STL r0, _LINK(r1) mr r4, r0 + /* Clear MSR to flag as ftrace_caller versus frace_regs_caller */ + li r8, 0 + PPC_STL r8, _MSR(r1) + /* Load &pt_regs in r6 for call below */ addi r6, r1 ,STACK_FRAME_OVERHEAD