/* * linux/kernel/time/timecounter.c * * based on code that migrated away from * linux/kernel/time/clocksource.c * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #include #include void timecounter_init(struct timecounter *tc, const struct cyclecounter *cc, u64 start_tstamp) { tc->cc = cc; tc->cycle_last = cc->read(cc); tc->nsec = start_tstamp; tc->mask = (1ULL << cc->shift) - 1; tc->frac = 0; } EXPORT_SYMBOL_GPL(timecounter_init); /** * timecounter_read_delta - get nanoseconds since last call of this function * @tc: Pointer to time counter * * When the underlying cycle counter runs over, this will be handled * correctly as long as it does not run over more than once between * calls. * * The first call to this function for a new time counter initializes * the time tracking and returns an undefined result. */ static u64 timecounter_read_delta(struct timecounter *tc) { u64 cycle_now, cycle_delta; u64 ns_offset; /* read cycle counter: */ cycle_now = tc->cc->read(tc->cc); /* calculate the delta since the last timecounter_read_delta(): */ cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask; /* convert to nanoseconds: */ ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta, tc->mask, &tc->frac); /* update time stamp of timecounter_read_delta() call: */ tc->cycle_last = cycle_now; return ns_offset; } u64 timecounter_read(struct timecounter *tc) { u64 nsec; /* increment time by nanoseconds since last call */ nsec = timecounter_read_delta(tc); nsec += tc->nsec; tc->nsec = nsec; return nsec; } EXPORT_SYMBOL_GPL(timecounter_read); /* * This is like cyclecounter_cyc2ns(), but it is used for computing a * time previous to the time stored in the cycle counter. */ static u64 cc_cyc2ns_backwards(const struct cyclecounter *cc, u64 cycles, u64 mask, u64 frac) { u64 ns = (u64) cycles; ns = ((ns * cc->mult) - frac) >> cc->shift; return ns; } u64 timecounter_cyc2time(struct timecounter *tc, u64 cycle_tstamp) { u64 delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask; u64 nsec = tc->nsec, frac = tc->frac; /* * Instead of always treating cycle_tstamp as more recent * than tc->cycle_last, detect when it is too far in the * future and treat it as old time stamp instead. */ if (delta > tc->cc->mask / 2) { delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask; nsec -= cc_cyc2ns_backwards(tc->cc, delta, tc->mask, frac); } else { nsec += cyclecounter_cyc2ns(tc->cc, delta, tc->mask, &frac); } return nsec; } EXPORT_SYMBOL_GPL(timecounter_cyc2time); f259ba09c'>kernel/bounds.c
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authorBorislav Petkov <bp@suse.de>2017-01-20 21:29:40 +0100
committerThomas Gleixner <tglx@linutronix.de>2017-01-23 09:39:55 +0100
commitc26665ab5c49ad3e142e0f054ca3204f259ba09c (patch)
tree3bab11918e18e9d25ef7544dba05cdf39d1abec5 /kernel/bounds.c
parent7a308bb3016f57e5be11a677d15b821536419d36 (diff)
x86/microcode/intel: Drop stashed AP patch pointer optimization
This was meant to save us the scanning of the microcode containter in the initrd since the first AP had already done that but it can also hurt us: Imagine a single hyperthreaded CPU (Intel(R) Atom(TM) CPU N270, for example) which updates the microcode on the BSP but since the microcode engine is shared between the two threads, the update on CPU1 doesn't happen because it has already happened on CPU0 and we don't find a newer microcode revision on CPU1. Which doesn't set the intel_ucode_patch pointer and at initrd jettisoning time we don't save the microcode patch for later application. Now, when we suspend to RAM, the loaded microcode gets cleared so we need to reload but there's no patch saved in the cache. Removing the optimization fixes this issue and all is fine and dandy. Fixes: 06b8534cb728 ("x86/microcode: Rework microcode loading") Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170120202955.4091-2-bp@alien8.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/bounds.c')