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=-11.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,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 11538C48BE4 for ; Mon, 24 Jun 2019 01:41:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CAF8922CEB for ; Mon, 24 Jun 2019 01:41:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="vzwMQXl6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726658AbfFXBlG (ORCPT ); Sun, 23 Jun 2019 21:41:06 -0400 Received: from terminus.zytor.com ([198.137.202.136]:51211 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726608AbfFXBlC (ORCPT ); Sun, 23 Jun 2019 21:41:02 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id x5NNjFWu2858551 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Sun, 23 Jun 2019 16:45:16 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 terminus.zytor.com x5NNjFWu2858551 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2019061801; t=1561333517; bh=Evgqj95MxCdHmrZD9Gj/G1s1uNeyfycUHVgn0y35FwY=; h=Date:From:Cc:Reply-To:In-Reply-To:References:To:Subject:From; b=vzwMQXl6F/0bcG+i79Vt41249va70n6G8sVL0UTGykrAQHETTe5409WZUHxtbtLI2 hDNzUCOtLYihLjMzJdPfbGROagn9dx/tVbRhidB8tbs1xleSDD6jbgW+R1OzRP90eo zBLf4Zo5z/yK39FydSmwOutTFFmaxUV7XIboRxYUDlCWAAJ/k3aVZbHrcb0g4s0w3f GGcHT35sK/q8tzhQEn3TtlL9zQLw50Vh/IqSU+2h2rjw4vqyXluApaPH0kYVuZlbLM t+f/766MdFefdi9z5QBAjTT/gUkXV1TJY0bunaeFEUN348D+DtNpMbI+7eVKLKdtNo Omx2Sni6p+VRg== Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id x5NNjFC22858548; Sun, 23 Jun 2019 16:45:15 -0700 Date: Sun, 23 Jun 2019 16:45:15 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Vincenzo Frascino Message-ID: Cc: pcc@google.com, salyzyn@android.com, linux@armlinux.org.uk, shuah@kernel.org, mingo@kernel.org, paul.burton@mips.com, 0x7f454c46@gmail.com, huw@codeweavers.com, sthotton@marvell.com, hpa@zytor.com, andre.przywara@arm.com, vincenzo.frascino@arm.com, daniel.lezcano@linaro.org, catalin.marinas@arm.com, linux@rasmusvillemoes.dk, ralf@linux-mips.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, will.deacon@arm.com, arnd@arndb.de Reply-To: pcc@google.com, linux@armlinux.org.uk, salyzyn@android.com, shuah@kernel.org, mingo@kernel.org, paul.burton@mips.com, 0x7f454c46@gmail.com, huw@codeweavers.com, hpa@zytor.com, sthotton@marvell.com, vincenzo.frascino@arm.com, andre.przywara@arm.com, daniel.lezcano@linaro.org, linux@rasmusvillemoes.dk, catalin.marinas@arm.com, ralf@linux-mips.org, linux-kernel@vger.kernel.org, will.deacon@arm.com, tglx@linutronix.de, arnd@arndb.de In-Reply-To: <20190621095252.32307-3-vincenzo.frascino@arm.com> References: <20190621095252.32307-3-vincenzo.frascino@arm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/vdso] lib/vdso: Provide generic VDSO implementation Git-Commit-ID: 00b26474c2f1613d7ab894c525f775c67c8a9e8f X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 00b26474c2f1613d7ab894c525f775c67c8a9e8f Gitweb: https://git.kernel.org/tip/00b26474c2f1613d7ab894c525f775c67c8a9e8f Author: Vincenzo Frascino AuthorDate: Fri, 21 Jun 2019 10:52:29 +0100 Committer: Thomas Gleixner CommitDate: Sat, 22 Jun 2019 21:21:05 +0200 lib/vdso: Provide generic VDSO implementation In the last few years the kernel gained quite some architecture specific vdso implementations which contain very similar code. Introduce a generic VDSO implementation of gettimeofday() which will be shareable between architectures once they are converted over. The implementation is based on the current x86 VDSO code. [ tglx: Massaged changelog and made the kernel doc tabular ] Signed-off-by: Vincenzo Frascino Signed-off-by: Thomas Gleixner Tested-by: Shijith Thotton Tested-by: Andre Przywara Cc: linux-arch@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-mips@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Cc: Catalin Marinas Cc: Will Deacon Cc: Arnd Bergmann Cc: Russell King Cc: Ralf Baechle Cc: Paul Burton Cc: Daniel Lezcano Cc: Mark Salyzyn Cc: Peter Collingbourne Cc: Shuah Khan Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Rasmus Villemoes Cc: Huw Davies Link: https://lkml.kernel.org/r/20190621095252.32307-3-vincenzo.frascino@arm.com --- include/vdso/helpers.h | 56 ++++++++++++ lib/Kconfig | 5 ++ lib/vdso/Kconfig | 36 ++++++++ lib/vdso/Makefile | 22 +++++ lib/vdso/gettimeofday.c | 224 ++++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 343 insertions(+) diff --git a/include/vdso/helpers.h b/include/vdso/helpers.h new file mode 100644 index 000000000000..01641dbb68ef --- /dev/null +++ b/include/vdso/helpers.h @@ -0,0 +1,56 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __VDSO_HELPERS_H +#define __VDSO_HELPERS_H + +#ifndef __ASSEMBLY__ + +#include + +static __always_inline u32 vdso_read_begin(const struct vdso_data *vd) +{ + u32 seq; + + while ((seq = READ_ONCE(vd->seq)) & 1) + cpu_relax(); + + smp_rmb(); + return seq; +} + +static __always_inline u32 vdso_read_retry(const struct vdso_data *vd, + u32 start) +{ + u32 seq; + + smp_rmb(); + seq = READ_ONCE(vd->seq); + return seq != start; +} + +static __always_inline void vdso_write_begin(struct vdso_data *vd) +{ + /* + * WRITE_ONCE it is required otherwise the compiler can validly tear + * updates to vd[x].seq and it is possible that the value seen by the + * reader it is inconsistent. + */ + WRITE_ONCE(vd[CS_HRES_COARSE].seq, vd[CS_HRES_COARSE].seq + 1); + WRITE_ONCE(vd[CS_RAW].seq, vd[CS_RAW].seq + 1); + smp_wmb(); +} + +static __always_inline void vdso_write_end(struct vdso_data *vd) +{ + smp_wmb(); + /* + * WRITE_ONCE it is required otherwise the compiler can validly tear + * updates to vd[x].seq and it is possible that the value seen by the + * reader it is inconsistent. + */ + WRITE_ONCE(vd[CS_HRES_COARSE].seq, vd[CS_HRES_COARSE].seq + 1); + WRITE_ONCE(vd[CS_RAW].seq, vd[CS_RAW].seq + 1); +} + +#endif /* !__ASSEMBLY__ */ + +#endif /* __VDSO_HELPERS_H */ diff --git a/lib/Kconfig b/lib/Kconfig index 90623a0e1942..8c8eefc5e54c 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -576,6 +576,11 @@ config OID_REGISTRY config UCS2_STRING tristate +# +# generic vdso +# +source "lib/vdso/Kconfig" + source "lib/fonts/Kconfig" config SG_SPLIT diff --git a/lib/vdso/Kconfig b/lib/vdso/Kconfig new file mode 100644 index 000000000000..cc00364bd2c2 --- /dev/null +++ b/lib/vdso/Kconfig @@ -0,0 +1,36 @@ +# SPDX-License-Identifier: GPL-2.0 + +config HAVE_GENERIC_VDSO + bool + +if HAVE_GENERIC_VDSO + +config GENERIC_GETTIMEOFDAY + bool + help + This is a generic implementation of gettimeofday vdso. + Each architecture that enables this feature has to + provide the fallback implementation. + +config GENERIC_VDSO_32 + bool + depends on GENERIC_GETTIMEOFDAY && !64BIT + help + This config option helps to avoid possible performance issues + in 32 bit only architectures. + +config GENERIC_COMPAT_VDSO + bool + help + This config option enables the compat VDSO layer. + +config CROSS_COMPILE_COMPAT_VDSO + string "32 bit Toolchain prefix for compat vDSO" + default "" + depends on GENERIC_COMPAT_VDSO + help + Defines the cross-compiler prefix for compiling compat vDSO. + If a 64 bit compiler (i.e. x86_64) can compile the VDSO for + 32 bit, it does not need to define this parameter. + +endif diff --git a/lib/vdso/Makefile b/lib/vdso/Makefile new file mode 100644 index 000000000000..c415a685d61b --- /dev/null +++ b/lib/vdso/Makefile @@ -0,0 +1,22 @@ +# SPDX-License-Identifier: GPL-2.0 + +GENERIC_VDSO_MK_PATH := $(abspath $(lastword $(MAKEFILE_LIST))) +GENERIC_VDSO_DIR := $(dir $(GENERIC_VDSO_MK_PATH)) + +c-gettimeofday-$(CONFIG_GENERIC_GETTIMEOFDAY) := $(addprefix $(GENERIC_VDSO_DIR), gettimeofday.c) + +# This cmd checks that the vdso library does not contain absolute relocation +# It has to be called after the linking of the vdso library and requires it +# as a parameter. +# +# $(ARCH_REL_TYPE_ABS) is defined in the arch specific makefile and corresponds +# to the absolute relocation types printed by "objdump -R" and accepted by the +# dynamic linker. +ifndef ARCH_REL_TYPE_ABS +$(error ARCH_REL_TYPE_ABS is not set) +endif + +quiet_cmd_vdso_check = VDSOCHK $@ + cmd_vdso_check = if $(OBJDUMP) -R $@ | egrep -h "$(ARCH_REL_TYPE_ABS)"; \ + then (echo >&2 "$@: dynamic relocations are not supported"; \ + rm -f $@; /bin/false); fi diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c new file mode 100644 index 000000000000..767d3a0bcb06 --- /dev/null +++ b/lib/vdso/gettimeofday.c @@ -0,0 +1,224 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Generic userspace implementations of gettimeofday() and similar. + */ +#include +#include +#include +#include +#include +#include +#include + +/* + * The generic vDSO implementation requires that gettimeofday.h + * provides: + * - __arch_get_vdso_data(): to get the vdso datapage. + * - __arch_get_hw_counter(): to get the hw counter based on the + * clock_mode. + * - gettimeofday_fallback(): fallback for gettimeofday. + * - clock_gettime_fallback(): fallback for clock_gettime. + * - clock_getres_fallback(): fallback for clock_getres. + */ +#include + +static int do_hres(const struct vdso_data *vd, clockid_t clk, + struct __kernel_timespec *ts) +{ + const struct vdso_timestamp *vdso_ts = &vd->basetime[clk]; + u64 cycles, last, sec, ns; + u32 seq; + + do { + seq = vdso_read_begin(vd); + cycles = __arch_get_hw_counter(vd->clock_mode) & + vd->mask; + ns = vdso_ts->nsec; + last = vd->cycle_last; + if (unlikely((s64)cycles < 0)) + return clock_gettime_fallback(clk, ts); + if (cycles > last) + ns += (cycles - last) * vd->mult; + ns >>= vd->shift; + sec = vdso_ts->sec; + } while (unlikely(vdso_read_retry(vd, seq))); + + /* + * Do this outside the loop: a race inside the loop could result + * in __iter_div_u64_rem() being extremely slow. + */ + ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); + ts->tv_nsec = ns; + + return 0; +} + +static void do_coarse(const struct vdso_data *vd, clockid_t clk, + struct __kernel_timespec *ts) +{ + const struct vdso_timestamp *vdso_ts = &vd->basetime[clk]; + u32 seq; + + do { + seq = vdso_read_begin(vd); + ts->tv_sec = vdso_ts->sec; + ts->tv_nsec = vdso_ts->nsec; + } while (unlikely(vdso_read_retry(vd, seq))); +} + +static __maybe_unused int +__cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts) +{ + const struct vdso_data *vd = __arch_get_vdso_data(); + u32 msk; + + /* Check for negative values or invalid clocks */ + if (unlikely((u32) clock >= MAX_CLOCKS)) + goto fallback; + + /* + * Convert the clockid to a bitmask and use it to check which + * clocks are handled in the VDSO directly. + */ + msk = 1U << clock; + if (likely(msk & VDSO_HRES)) { + return do_hres(&vd[CS_HRES_COARSE], clock, ts); + } else if (msk & VDSO_COARSE) { + do_coarse(&vd[CS_HRES_COARSE], clock, ts); + return 0; + } else if (msk & VDSO_RAW) { + return do_hres(&vd[CS_RAW], clock, ts); + } + +fallback: + return clock_gettime_fallback(clock, ts); +} + +static __maybe_unused int +__cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res) +{ + struct __kernel_timespec ts; + int ret; + + if (res == NULL) + goto fallback; + + ret = __cvdso_clock_gettime(clock, &ts); + + if (ret == 0) { + res->tv_sec = ts.tv_sec; + res->tv_nsec = ts.tv_nsec; + } + + return ret; + +fallback: + return clock_gettime_fallback(clock, (struct __kernel_timespec *)res); +} + +static __maybe_unused int +__cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz) +{ + const struct vdso_data *vd = __arch_get_vdso_data(); + + if (likely(tv != NULL)) { + struct __kernel_timespec ts; + + if (do_hres(&vd[CS_HRES_COARSE], CLOCK_REALTIME, &ts)) + return gettimeofday_fallback(tv, tz); + + tv->tv_sec = ts.tv_sec; + tv->tv_usec = (u32)ts.tv_nsec / NSEC_PER_USEC; + } + + if (unlikely(tz != NULL)) { + tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest; + tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime; + } + + return 0; +} + +#ifdef VDSO_HAS_TIME +static __maybe_unused time_t __cvdso_time(time_t *time) +{ + const struct vdso_data *vd = __arch_get_vdso_data(); + time_t t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec); + + if (time) + *time = t; + + return t; +} +#endif /* VDSO_HAS_TIME */ + +#ifdef VDSO_HAS_CLOCK_GETRES +static __maybe_unused +int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res) +{ + const struct vdso_data *vd = __arch_get_vdso_data(); + u64 ns; + u32 msk; + u64 hrtimer_res = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res); + + /* Check for negative values or invalid clocks */ + if (unlikely((u32) clock >= MAX_CLOCKS)) + goto fallback; + + /* + * Convert the clockid to a bitmask and use it to check which + * clocks are handled in the VDSO directly. + */ + msk = 1U << clock; + if (msk & VDSO_HRES) { + /* + * Preserves the behaviour of posix_get_hrtimer_res(). + */ + ns = hrtimer_res; + } else if (msk & VDSO_COARSE) { + /* + * Preserves the behaviour of posix_get_coarse_res(). + */ + ns = LOW_RES_NSEC; + } else if (msk & VDSO_RAW) { + /* + * Preserves the behaviour of posix_get_hrtimer_res(). + */ + ns = hrtimer_res; + } else { + goto fallback; + } + + if (res) { + res->tv_sec = 0; + res->tv_nsec = ns; + } + + return 0; + +fallback: + return clock_getres_fallback(clock, res); +} + +static __maybe_unused int +__cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res) +{ + struct __kernel_timespec ts; + int ret; + + if (res == NULL) + goto fallback; + + ret = __cvdso_clock_getres(clock, &ts); + + if (ret == 0) { + res->tv_sec = ts.tv_sec; + res->tv_nsec = ts.tv_nsec; + } + + return ret; + +fallback: + return clock_getres_fallback(clock, (struct __kernel_timespec *)res); +} +#endif /* VDSO_HAS_CLOCK_GETRES */