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=-10.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 1C34EC433E2 for ; Fri, 4 Sep 2020 11:03:30 +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 C283D2074D for ; Fri, 4 Sep 2020 11:03:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C283D2074D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=csgroup.eu 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 4BjZXv6hnkzDrCp for ; Fri, 4 Sep 2020 21:03:27 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=csgroup.eu (client-ip=93.17.236.30; helo=pegase1.c-s.fr; envelope-from=christophe.leroy@csgroup.eu; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=csgroup.eu Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4BjZVl2JWszDr45 for ; Fri, 4 Sep 2020 21:01:35 +1000 (AEST) Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4BjZVf4YvpzB09bQ; Fri, 4 Sep 2020 13:01:30 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id p6qrsTlmFVgo; Fri, 4 Sep 2020 13:01:30 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4BjZVf2pPlzB09bP; Fri, 4 Sep 2020 13:01:30 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id A12548B81C; Fri, 4 Sep 2020 13:01:31 +0200 (CEST) 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 oo9Efquu5ZWU; Fri, 4 Sep 2020 13:01:31 +0200 (CEST) Received: from po17688vm.idsi0.si.c-s.fr (unknown [10.25.210.31]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 731BC8B81B; Fri, 4 Sep 2020 13:01:31 +0200 (CEST) Received: by po17688vm.idsi0.si.c-s.fr (Postfix, from userid 0) id E4778653FF; Fri, 4 Sep 2020 11:01:30 +0000 (UTC) Message-Id: <94ba5a5138f99522e1562dbcdb38d31aa790dc89.1599216721.git.christophe.leroy@csgroup.eu> From: Christophe Leroy Subject: [PATCH 1/3] powerpc/uaccess: Switch __put_user_size_allowed() to __put_user_asm_goto() To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Date: Fri, 4 Sep 2020 11:01:30 +0000 (UTC) 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: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" __put_user_asm_goto() provides more flexibility to GCC and avoids using a local variable to tell if the write succeeded or not. GCC can then avoid implementing a cmp in the fast path. See the difference for a small function like the PPC64 version of save_general_regs() in arch/powerpc/kernel/signal_32.c: Before the patch (unreachable nop removed): 0000000000000c10 <.save_general_regs>: c10: 39 20 00 2c li r9,44 c14: 39 40 00 00 li r10,0 c18: 7d 29 03 a6 mtctr r9 c1c: 38 c0 00 00 li r6,0 c20: 48 00 00 14 b c34 <.save_general_regs+0x24> c30: 42 40 00 40 bdz c70 <.save_general_regs+0x60> c34: 28 2a 00 27 cmpldi r10,39 c38: 7c c8 33 78 mr r8,r6 c3c: 79 47 1f 24 rldicr r7,r10,3,60 c40: 39 20 00 01 li r9,1 c44: 41 82 00 0c beq c50 <.save_general_regs+0x40> c48: 7d 23 38 2a ldx r9,r3,r7 c4c: 79 29 00 20 clrldi r9,r9,32 c50: 91 24 00 00 stw r9,0(r4) c54: 2c 28 00 00 cmpdi r8,0 c58: 39 4a 00 01 addi r10,r10,1 c5c: 38 84 00 04 addi r4,r4,4 c60: 41 82 ff d0 beq c30 <.save_general_regs+0x20> c64: 38 60 ff f2 li r3,-14 c68: 4e 80 00 20 blr c70: 38 60 00 00 li r3,0 c74: 4e 80 00 20 blr 0000000000000000 <.fixup>: cc: 39 00 ff f2 li r8,-14 d0: 48 00 00 00 b d0 <.fixup+0xd0> d0: R_PPC64_REL24 .text+0xc54 After the patch: 0000000000001490 <.save_general_regs>: 1490: 39 20 00 2c li r9,44 1494: 39 40 00 00 li r10,0 1498: 7d 29 03 a6 mtctr r9 149c: 60 00 00 00 nop 14a0: 28 2a 00 27 cmpldi r10,39 14a4: 79 48 1f 24 rldicr r8,r10,3,60 14a8: 39 20 00 01 li r9,1 14ac: 41 82 00 0c beq 14b8 <.save_general_regs+0x28> 14b0: 7d 23 40 2a ldx r9,r3,r8 14b4: 79 29 00 20 clrldi r9,r9,32 14b8: 91 24 00 00 stw r9,0(r4) 14bc: 39 4a 00 01 addi r10,r10,1 14c0: 38 84 00 04 addi r4,r4,4 14c4: 42 00 ff dc bdnz 14a0 <.save_general_regs+0x10> 14c8: 38 60 00 00 li r3,0 14cc: 4e 80 00 20 blr 14d0: 38 60 ff f2 li r3,-14 14d4: 4e 80 00 20 blr Signed-off-by: Christophe Leroy --- arch/powerpc/include/asm/uaccess.h | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index a5cfe867fbdc..96d1c144f92b 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -189,14 +189,14 @@ extern long __put_user_bad(void); #define __put_user_size_allowed(x, ptr, size, retval) \ do { \ + __label__ __pu_failed; \ + \ retval = 0; \ - switch (size) { \ - case 1: __put_user_asm(x, ptr, retval, "stb"); break; \ - case 2: __put_user_asm(x, ptr, retval, "sth"); break; \ - case 4: __put_user_asm(x, ptr, retval, "stw"); break; \ - case 8: __put_user_asm2(x, ptr, retval); break; \ - default: __put_user_bad(); \ - } \ + __put_user_size_goto(x, ptr, size, __pu_failed); \ + break; \ + \ +__pu_failed: \ + retval = -EFAULT; \ } while (0) #define __put_user_size(x, ptr, size, retval) \ -- 2.25.0