From patchwork Thu Jan 16 17:58:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 11337521 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0EB5914B7 for ; Thu, 16 Jan 2020 17:59:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D64C0246A7 for ; Thu, 16 Jan 2020 17:59:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="PU7eTaOI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2394542AbgAPR62 (ORCPT ); Thu, 16 Jan 2020 12:58:28 -0500 Received: from pegase1.c-s.fr ([93.17.236.30]:50290 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2393889AbgAPR61 (ORCPT ); Thu, 16 Jan 2020 12:58:27 -0500 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 47zBkl4Rxnz9v0MT; Thu, 16 Jan 2020 18:58:23 +0100 (CET) Authentication-Results: localhost; dkim=pass reason="1024-bit key; insecure key" header.d=c-s.fr header.i=@c-s.fr header.b=PU7eTaOI; dkim-adsp=pass; dkim-atps=neutral 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 SjVALX4P8BV2; Thu, 16 Jan 2020 18:58:23 +0100 (CET) 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 47zBkl379cz9v0MQ; Thu, 16 Jan 2020 18:58:23 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=c-s.fr; s=mail; t=1579197503; bh=UUBKk15KITQNNRJp5evVzKMcsza8d4oSE6jeKhRMcDE=; h=From:Subject:To:Cc:Date:From; b=PU7eTaOIhtqxVjMZbHoIHKjqp9r3ETp1+1A3ditRGh62MKQuHKKpA1ukHm+n4/PQ8 KC/rDW+iuJ+YJeQ+75hFrx42zs79+bFb+B+mlB6Spffdcew/8JaUUYE+lQ+28d9Voa cGAdfy+u4wFjdM2xKEN8a7q76RRkglF0nFieQvTc= Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 187F68B82D; Thu, 16 Jan 2020 18:58:25 +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 Q42v6gYwsPbp; Thu, 16 Jan 2020 18:58:24 +0100 (CET) Received: from po14934vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 8EC048B82C; Thu, 16 Jan 2020 18:58:24 +0100 (CET) Received: by po14934vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 3689964A35; Thu, 16 Jan 2020 17:58:24 +0000 (UTC) Message-Id: From: Christophe Leroy Subject: [RFC PATCH v4 00/11] powerpc: switch VDSO to C implementation. To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , nathanl@linux.ibm.com, arnd@arndb.de, tglx@linutronix.de, vincenzo.frascino@arm.com, luto@kernel.org Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, x86@kernel.org Date: Thu, 16 Jan 2020 17:58:24 +0000 (UTC) Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org This is a fourth tentative to switch powerpc VDSO to generic C implementation. This version should work on PPC64 (untested). VDSO32 for PPC64 is impossible to build and has been de-activated, because the powerpc ASM header files for C are not prepared to build 32 bits code with CONFIG_PPC64. powerpc is a bit special for VDSO as well as system calls in the way that it requires setting CR SO bit which cannot be done in C. Therefore, entry/exit and fallback need to be performed in ASM. Note that on previous patches, a buggy version of vdsotest was used which was underestimating the time in gettimeofday compared to clock-get... functions. This series applies on a merge of powerpc/merge and tip/timers/core branches, series "lib/vdso: Bugfix and consolidation" (https://lore.kernel.org/patchwork/project/lkml/list/?series=425784) applied after the above merge. On a powerpc8xx, with current powerpc/32 ASM VDSO: gettimeofday: vdso: 907 nsec/call clock-getres-realtime: vdso: 484 nsec/call clock-gettime-realtime: vdso: 899 nsec/call The first patch adds VDSO generic C support without any changes to common code. Performance is as follows: gettimeofday: vdso: 1211 nsec/call clock-getres-realtime: vdso: 722 nsec/call clock-gettime-realtime: vdso: 1216 nsec/call Then a few changes in the common code have allowed performance improvement. At the end of the series we have: gettimeofday: vdso: 974 nsec/call clock-getres-realtime: vdso: 545 nsec/call clock-gettime-realtime: vdso: 941 nsec/call The final result is rather close to pure ASM VDSO: * 7% more on gettimeofday (9 cycles) * 5% more on clock-gettime-realtime (6 cycles) * 12% more on clock-getres-realtime (8 cycles) Due to the unavoidable ASM trampoline, we won't get much closer but that should be acceptable for a port from ASM to a generic C code (here, 1 cycle is about 7,5 ns) Christophe Leroy (11): powerpc/64: Don't provide time functions in compat VDSO32 powerpc/vdso: Switch VDSO to generic C implementation. lib: vdso: only read hrtimer_res when needed in __cvdso_clock_getres() powerpc/vdso: simplify __get_datapage() lib: vdso: allow arches to provide vdso data pointer powerpc/vdso: provide inline alternative to __get_datapage() powerpc/vdso: provide vdso data pointer from the ASM caller. lib: vdso: allow fixed clock mode powerpc/vdso: override __arch_vdso_capable() lib: vdso: Allow arches to override the ns shift operation powerpc/32: provide vdso_shift_ns() arch/powerpc/Kconfig | 2 + arch/powerpc/include/asm/clocksource.h | 6 + arch/powerpc/include/asm/vdso/gettimeofday.h | 117 ++++++++++++ arch/powerpc/include/asm/vdso/vsyscall.h | 25 +++ arch/powerpc/include/asm/vdso_datapage.h | 52 +++--- arch/powerpc/kernel/asm-offsets.c | 46 +---- arch/powerpc/kernel/time.c | 91 +--------- arch/powerpc/kernel/vdso.c | 58 ++---- arch/powerpc/kernel/vdso32/Makefile | 27 ++- arch/powerpc/kernel/vdso32/datapage.S | 10 +- arch/powerpc/kernel/vdso32/gettimeofday.S | 258 ++++----------------------- arch/powerpc/kernel/vdso32/vdso32.lds.S | 9 +- arch/powerpc/kernel/vdso32/vgettimeofday.c | 29 +++ arch/powerpc/kernel/vdso64/Makefile | 23 ++- arch/powerpc/kernel/vdso64/datapage.S | 13 +- arch/powerpc/kernel/vdso64/gettimeofday.S | 257 ++++---------------------- arch/powerpc/kernel/vdso64/vdso64.lds.S | 7 +- arch/powerpc/kernel/vdso64/vgettimeofday.c | 29 +++ lib/vdso/gettimeofday.c | 107 ++++++++--- 19 files changed, 457 insertions(+), 709 deletions(-) create mode 100644 arch/powerpc/include/asm/clocksource.h create mode 100644 arch/powerpc/include/asm/vdso/gettimeofday.h create mode 100644 arch/powerpc/include/asm/vdso/vsyscall.h create mode 100644 arch/powerpc/kernel/vdso32/vgettimeofday.c create mode 100644 arch/powerpc/kernel/vdso64/vgettimeofday.c