linux/arch
Thomas Gleixner f2e04214ef x86/tsc: Avoid the large time jump when sanitizing TSC ADJUST
Olof reported that on a machine which has a BIOS wreckaged TSC the
timestamps in dmesg are making a large jump because the TSC value is
jumping forward after resetting the TSC ADJUST register to a sane value.

This can be avoided by calling the TSC ADJUST saniziting function before
initializing the per cpu sched clock machinery. That takes the offset into
account and avoid the time jump.

What cannot be avoided is that the 'Firmware Bug' warnings on the secondary
CPUs are printed with the large time offsets because it would be too much
effort and ugly hackery to print those warnings into a buffer and emit them
after the adjustemt on the starting CPUs. It's a firmware bug and should be
fixed in firmware. The weird timestamps are collateral damage and just
illustrate the sillyness of the BIOS folks:

[    0.397445] smp: Bringing up secondary CPUs ...
[    0.402100] x86: Booting SMP configuration:
[    0.406343] .... node  #0, CPUs:      #1
[1265776479.930667] [Firmware Bug]: TSC ADJUST differs: Reference CPU0: -2978888639075328 CPU1: -2978888639183101
[1265776479.944664] TSC ADJUST synchronize: Reference CPU0: 0 CPU1: -2978888639183101
[    0.508119]  #2
[1265776480.032346] [Firmware Bug]: TSC ADJUST differs: Reference CPU0: -2978888639075328 CPU2: -2978888639183677
[1265776480.044192] TSC ADJUST synchronize: Reference CPU0: 0 CPU2: -2978888639183677
[    0.607643]  #3
[1265776480.131874] [Firmware Bug]: TSC ADJUST differs: Reference CPU0: -2978888639075328 CPU3: -2978888639184530
[1265776480.143720] TSC ADJUST synchronize: Reference CPU0: 0 CPU3: -2978888639184530
[    0.707108] smp: Brought up 1 node, 4 CPUs
[    0.711271] smpboot: Total of 4 processors activated (21698.88 BogoMIPS)

Reported-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170209151231.411460506@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-02-10 09:47:16 +01:00
..
alpha clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
arc ARC: [arcompact] handle unaligned access delay slot corner case 2017-01-27 10:54:20 -08:00
arm KVM fixes for v4.10-rc5 2017-01-20 14:19:34 -08:00
arm64 Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-02-01 09:24:00 -08:00
avr32 clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
blackfin Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
c6x clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
cris Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
frv frv: add missing atomic64 operations 2017-01-24 16:26:14 -08:00
h8300 Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
hexagon clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
ia64 clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
m32r Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
m68k clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
metag Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:05:56 -08:00
microblaze clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
mips KVM fixes for v4.10-rc3 2017-01-06 15:27:17 -08:00
mn10300 mn10300: fix build error of missing fpu_save() 2017-01-24 16:26:14 -08:00
nios2 clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
openrisc openrisc: Add _text symbol to fix ksym build error 2017-01-02 10:35:11 +09:00
parisc parisc: Don't use BITS_PER_LONG in userspace-exported swab.h header 2017-01-28 21:54:23 +01:00
powerpc powerpc fixes for 4.10 #3 2017-02-03 11:10:06 -08:00
s390 s390/mm: Fix cmma unused transfer from pgste into pte 2017-01-24 16:03:42 +01:00
score Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
sh Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
sparc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc 2017-01-30 15:47:19 -08:00
tile tile/ptrace: Preserve previous registers for short regset write 2017-01-06 15:14:08 -05:00
um clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
unicore32 clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
x86 x86/tsc: Avoid the large time jump when sanitizing TSC ADJUST 2017-02-10 09:47:16 +01:00
xtensa Xtensa fix for v4.10-rc7: 2017-02-02 12:39:10 -08:00
.gitignore
Kconfig powerpc: ima: get the kexec buffer passed by the previous kernel 2016-12-20 09:48:40 -08:00