From patchwork Thu Dec 1 07:56:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 13061030 X-Patchwork-Delegate: bpf@iogearbox.net 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 073D0C43217 for ; Thu, 1 Dec 2022 07:57:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229904AbiLAH5c (ORCPT ); Thu, 1 Dec 2022 02:57:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35482 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229875AbiLAH53 (ORCPT ); Thu, 1 Dec 2022 02:57:29 -0500 Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8502D532F8; Wed, 30 Nov 2022 23:57:11 -0800 (PST) Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4NN7hH2FBjz9sZt; Thu, 1 Dec 2022 08:57:03 +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 M1e-p4nP_thr; Thu, 1 Dec 2022 08:57:03 +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 4NN7hD43Snz9sZx; Thu, 1 Dec 2022 08:57:00 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 78E138B763; Thu, 1 Dec 2022 08:57:00 +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 sFoZRa7m0HU2; Thu, 1 Dec 2022 08:57:00 +0100 (CET) Received: from PO20335.IDSI0.si.c-s.fr (unknown [172.25.230.108]) by messagerie.si.c-s.fr (Postfix) with ESMTP id C7A9A8B781; Thu, 1 Dec 2022 08:56:59 +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 2B17uudK130816 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Thu, 1 Dec 2022 08:56:56 +0100 Received: (from chleroy@localhost) by PO20335.IDSI0.si.c-s.fr (8.17.1/8.17.1/Submit) id 2B17uuGg130811; Thu, 1 Dec 2022 08:56:56 +0100 X-Authentication-Warning: PO20335.IDSI0.si.c-s.fr: chleroy set sender to christophe.leroy@csgroup.eu using -f From: Christophe Leroy To: Michael Ellerman , Nicholas Piggin , "Naveen N. Rao" Cc: Christophe Leroy , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, bpf@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa Subject: [PATCH v1 03/10] powerpc/bpf/32: No need to zeroise r4 when not doing tail call Date: Thu, 1 Dec 2022 08:56:28 +0100 Message-Id: X-Mailer: git-send-email 2.38.1 In-Reply-To: References: MIME-Version: 1.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1669881390; l=924; s=20211009; h=from:subject:message-id; bh=I16YVnQHQYIVB+npE1u3C3GDSkabRAUr5Fvl4cfu+v0=; b=o0mZ6QHayEwIm1KTsJGpiPMhIaZvo4OWxBY/I4a2MD0/kDcSY21VZgAEGsSFqwqLB+SJuUMAHhid 2fTOIp91A3eQBLgEWx4H7HSOA1ju9k+LQGovkHpdH5GEUXhVCZzy X-Developer-Key: i=christophe.leroy@csgroup.eu; a=ed25519; pk=HIzTzUj91asvincQGOFx6+ZF5AoUuP9GdOtQChs7Mm0= Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net r4 is cleared at function entry and used as tail call count. But when the function does not perform tail call, r4 is ignored, so no need to clear it. Replace it by a NOP in that case. Signed-off-by: Christophe Leroy --- arch/powerpc/net/bpf_jit_comp32.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index a379b0ce19ff..4e6caee9c98a 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c @@ -114,7 +114,10 @@ void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) int i; /* Initialize tail_call_cnt, to be skipped if we do tail calls. */ - EMIT(PPC_RAW_LI(_R4, 0)); + if (ctx->seen & SEEN_TAILCALL) + EMIT(PPC_RAW_LI(_R4, 0)); + else + EMIT(PPC_RAW_NOP()); #define BPF_TAILCALL_PROLOGUE_SIZE 4