From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751743AbdGYMRk (ORCPT ); Tue, 25 Jul 2017 08:17:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36784 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750839AbdGYMRi (ORCPT ); Tue, 25 Jul 2017 08:17:38 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 92EEC285B9 Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=prarit@redhat.com From: Prarit Bhargava To: linux-kernel@vger.kernel.org Cc: Prarit Bhargava , Mark Salyzyn , Jonathan Corbet , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , John Stultz , Thomas Gleixner , Stephen Boyd , Andrew Morton , Greg Kroah-Hartman , "Paul E. McKenney" , Christoffer Dall , Deepa Dinamani , Ingo Molnar , Joel Fernandes , Kees Cook , Peter Zijlstra , Geert Uytterhoeven , "Luis R. Rodriguez" , Nicholas Piggin , "Jason A. Donenfeld" , Olof Johansson , "Theodore Ts'o" , Josh Poimboeuf , linux-doc@vger.kernel.org Subject: [PATCH 0/2] printk: allow different timestamps for printk.time Date: Tue, 25 Jul 2017 08:17:25 -0400 Message-Id: <1500985047-23038-1-git-send-email-prarit@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 25 Jul 2017 12:17:38 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Over the past years I've seen many reports of bugs that include time-stamped kernel logs (enabled when CONFIG_PRINTK_TIME=y or print.time=1 is specified as a kernel parameter) that do not align with either external time stamped logs or /var/log/messages. This also makes determining the time of a failure difficult in cases where /var/log/messages is unavailable. For example, [root@intel-wildcatpass-06 ~]# date; echo "Hello!" > /dev/kmsg ; date Thu Jul 20 11:38:22 EST 2017 Thu Jul 20 11:38:22 EST 2017 which displays [83973.768912] Hello! on the serial console. Running a script to convert this to the stamped time, [root@intel-wildcatpass-06 ~]# ./human.sh | tail -1 [Thu July 17 11:39:45 2017] Hello! which is already off by 1 minute and 23 seconds off after ~24 hours of uptime. This occurs because the printk time stamp is obtained from a call to local_clock() which (on x86) is a direct call to the hardware. These hardware clock reads are not modified by the standard ntp or ptp protocol The other timestamps are and that results in situations external time sources are further and further offset from the kernel log timestamps. Implement printk.time settings to allow a user to specify the monotonic or real clocks. The default is the local clock (hardware clock). Real clock & 32-bit systems: Selecting the real clock printk timestamp may lead to unlikely situations where a timestamp is wrong because the real time offset is read without the protection of a sequence lock in the call to ktime_get_log_ts() in printk_get_ts(). Signed-off-by: Prarit Bhargava Cc: Mark Salyzyn Cc: Jonathan Corbet Cc: Petr Mladek Cc: Sergey Senozhatsky Cc: Steven Rostedt Cc: John Stultz Cc: Thomas Gleixner Cc: Stephen Boyd Cc: Andrew Morton Cc: Greg Kroah-Hartman Cc: "Paul E. McKenney" Cc: Christoffer Dall Cc: Deepa Dinamani Cc: Ingo Molnar Cc: Joel Fernandes Cc: Kees Cook Cc: Peter Zijlstra Cc: Geert Uytterhoeven Cc: "Luis R. Rodriguez" Cc: Nicholas Piggin Cc: "Jason A. Donenfeld" Cc: Olof Johansson Cc: "Theodore Ts'o" Cc: Josh Poimboeuf Cc: linux-doc@vger.kernel.org Prarit Bhargava (2): printk: Make CONFIG_PRINTK_TIME an int printk: Add boottime and real timestamps Documentation/admin-guide/kernel-parameters.txt | 6 +- arch/arm/configs/aspeed_g4_defconfig | 2 +- arch/arm/configs/aspeed_g5_defconfig | 2 +- arch/arm/configs/axm55xx_defconfig | 2 +- arch/arm/configs/bcm2835_defconfig | 2 +- arch/arm/configs/colibri_pxa270_defconfig | 2 +- arch/arm/configs/colibri_pxa300_defconfig | 2 +- arch/arm/configs/dove_defconfig | 2 +- arch/arm/configs/efm32_defconfig | 2 +- arch/arm/configs/exynos_defconfig | 2 +- arch/arm/configs/ezx_defconfig | 2 +- arch/arm/configs/h5000_defconfig | 2 +- arch/arm/configs/hisi_defconfig | 2 +- arch/arm/configs/imote2_defconfig | 2 +- arch/arm/configs/imx_v6_v7_defconfig | 2 +- arch/arm/configs/keystone_defconfig | 2 +- arch/arm/configs/lpc18xx_defconfig | 2 +- arch/arm/configs/magician_defconfig | 2 +- arch/arm/configs/mmp2_defconfig | 2 +- arch/arm/configs/moxart_defconfig | 2 +- arch/arm/configs/mps2_defconfig | 2 +- arch/arm/configs/multi_v7_defconfig | 2 +- arch/arm/configs/mvebu_v7_defconfig | 2 +- arch/arm/configs/mxs_defconfig | 2 +- arch/arm/configs/omap2plus_defconfig | 2 +- arch/arm/configs/pxa168_defconfig | 2 +- arch/arm/configs/pxa3xx_defconfig | 2 +- arch/arm/configs/pxa910_defconfig | 2 +- arch/arm/configs/pxa_defconfig | 2 +- arch/arm/configs/qcom_defconfig | 2 +- arch/arm/configs/raumfeld_defconfig | 2 +- arch/arm/configs/shmobile_defconfig | 2 +- arch/arm/configs/socfpga_defconfig | 2 +- arch/arm/configs/stm32_defconfig | 2 +- arch/arm/configs/sunxi_defconfig | 2 +- arch/arm/configs/tango4_defconfig | 2 +- arch/arm/configs/tegra_defconfig | 2 +- arch/arm/configs/u300_defconfig | 2 +- arch/arm/configs/u8500_defconfig | 2 +- arch/arm/configs/vt8500_v6_v7_defconfig | 2 +- arch/arm/configs/xcep_defconfig | 2 +- arch/arm/configs/zx_defconfig | 2 +- arch/arm64/configs/defconfig | 2 +- arch/m68k/configs/amcore_defconfig | 2 +- arch/mips/configs/ath25_defconfig | 2 +- arch/mips/configs/bcm47xx_defconfig | 2 +- arch/mips/configs/bmips_be_defconfig | 2 +- arch/mips/configs/bmips_stb_defconfig | 2 +- arch/mips/configs/ci20_defconfig | 2 +- arch/mips/configs/generic_defconfig | 2 +- arch/mips/configs/lemote2f_defconfig | 2 +- arch/mips/configs/loongson3_defconfig | 2 +- arch/mips/configs/nlm_xlp_defconfig | 2 +- arch/mips/configs/nlm_xlr_defconfig | 2 +- arch/mips/configs/pistachio_defconfig | 2 +- arch/mips/configs/qi_lb60_defconfig | 2 +- arch/mips/configs/rt305x_defconfig | 2 +- arch/mips/configs/xway_defconfig | 2 +- arch/parisc/configs/generic-64bit_defconfig | 2 +- arch/powerpc/configs/40x/virtex_defconfig | 2 +- arch/powerpc/configs/44x/fsp2_defconfig | 2 +- arch/powerpc/configs/44x/virtex5_defconfig | 2 +- arch/powerpc/configs/44x/warp_defconfig | 2 +- arch/powerpc/configs/52xx/cm5200_defconfig | 2 +- arch/powerpc/configs/52xx/lite5200b_defconfig | 2 +- arch/powerpc/configs/52xx/motionpro_defconfig | 2 +- arch/powerpc/configs/52xx/tqm5200_defconfig | 2 +- arch/powerpc/configs/gamecube_defconfig | 2 +- arch/powerpc/configs/mpc5200_defconfig | 2 +- arch/powerpc/configs/pasemi_defconfig | 2 +- arch/powerpc/configs/wii_defconfig | 2 +- arch/s390/configs/default_defconfig | 2 +- arch/s390/configs/gcov_defconfig | 2 +- arch/s390/configs/performance_defconfig | 2 +- arch/s390/configs/zfcpdump_defconfig | 2 +- arch/sh/configs/edosk7760_defconfig | 2 +- arch/sh/configs/sdk7786_defconfig | 2 +- arch/sh/configs/se7722_defconfig | 2 +- arch/sh/configs/sh7785lcr_32bit_defconfig | 2 +- arch/sh/configs/urquell_defconfig | 2 +- arch/sparc/configs/sparc64_defconfig | 2 +- arch/x86/configs/i386_defconfig | 2 +- arch/x86/configs/x86_64_defconfig | 2 +- arch/xtensa/configs/audio_kc705_defconfig | 2 +- arch/xtensa/configs/cadence_csp_defconfig | 2 +- arch/xtensa/configs/generic_kc705_defconfig | 2 +- arch/xtensa/configs/nommu_kc705_defconfig | 2 +- arch/xtensa/configs/smp_lx200_defconfig | 2 +- include/linux/timekeeping.h | 1 + kernel/printk/printk.c | 95 +++++++++++++++++++++- kernel/time/timekeeping.c | 14 ++++ lib/Kconfig.debug | 8 +- .../selftests/rcutorture/configs/lock/CFcommon | 2 +- .../selftests/rcutorture/configs/rcu/CFcommon | 2 +- .../selftests/rcutorture/configs/rcuperf/CFcommon | 2 +- 95 files changed, 206 insertions(+), 98 deletions(-) -- 1.8.5.5