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authorLinus Torvalds <torvalds@linux-foundation.org>2014-08-05 17:46:42 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-05 17:46:42 -0700
commite7fda6c4c3c1a7d6996dd75fd84670fa0b5d448f (patch)
treedaa51c16462c318b890acf7f01fba5827275dd74 /arch/x86/kernel
parent08d69a25714429850cf9ef71f22d8cdc9189d93f (diff)
parent953dec21aed4038464fec02f96a2f1b8701a5bce (diff)
downloadlinux-e7fda6c4c3c1a7d6996dd75fd84670fa0b5d448f.tar.bz2
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer and time updates from Thomas Gleixner: "A rather large update of timers, timekeeping & co - Core timekeeping code is year-2038 safe now for 32bit machines. Now we just need to fix all in kernel users and the gazillion of user space interfaces which rely on timespec/timeval :) - Better cache layout for the timekeeping internal data structures. - Proper nanosecond based interfaces for in kernel users. - Tree wide cleanup of code which wants nanoseconds but does hoops and loops to convert back and forth from timespecs. Some of it definitely belongs into the ugly code museum. - Consolidation of the timekeeping interface zoo. - A fast NMI safe accessor to clock monotonic for tracing. This is a long standing request to support correlated user/kernel space traces. With proper NTP frequency correction it's also suitable for correlation of traces accross separate machines. - Checkpoint/restart support for timerfd. - A few NOHZ[_FULL] improvements in the [hr]timer code. - Code move from kernel to kernel/time of all time* related code. - New clocksource/event drivers from the ARM universe. I'm really impressed that despite an architected timer in the newer chips SoC manufacturers insist on inventing new and differently broken SoC specific timers. [ Ed. "Impressed"? I don't think that word means what you think it means ] - Another round of code move from arch to drivers. Looks like most of the legacy mess in ARM regarding timers is sorted out except for a few obnoxious strongholds. - The usual updates and fixlets all over the place" * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (114 commits) timekeeping: Fixup typo in update_vsyscall_old definition clocksource: document some basic timekeeping concepts timekeeping: Use cached ntp_tick_length when accumulating error timekeeping: Rework frequency adjustments to work better w/ nohz timekeeping: Minor fixup for timespec64->timespec assignment ftrace: Provide trace clocks monotonic timekeeping: Provide fast and NMI safe access to CLOCK_MONOTONIC seqcount: Add raw_write_seqcount_latch() seqcount: Provide raw_read_seqcount() timekeeping: Use tk_read_base as argument for timekeeping_get_ns() timekeeping: Create struct tk_read_base and use it in struct timekeeper timekeeping: Restructure the timekeeper some more clocksource: Get rid of cycle_last clocksource: Move cycle_last validation to core code clocksource: Make delta calculation a function wireless: ath9k: Get rid of timespec conversions drm: vmwgfx: Use nsec based interfaces drm: i915: Use nsec based interfaces timekeeping: Provide ktime_get_raw() hangcheck-timer: Use ktime_get_ns() ...
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/tsc.c21
-rw-r--r--arch/x86/kernel/vsyscall_gtod.c23
2 files changed, 21 insertions, 23 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 56b0c338061e..b6025f9e36c6 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -950,7 +950,7 @@ core_initcall(cpufreq_tsc);
static struct clocksource clocksource_tsc;
/*
- * We compare the TSC to the cycle_last value in the clocksource
+ * We used to compare the TSC to the cycle_last value in the clocksource
* structure to avoid a nasty time-warp. This can be observed in a
* very small window right after one CPU updated cycle_last under
* xtime/vsyscall_gtod lock and the other CPU reads a TSC value which
@@ -960,26 +960,23 @@ static struct clocksource clocksource_tsc;
* due to the unsigned delta calculation of the time keeping core
* code, which is necessary to support wrapping clocksources like pm
* timer.
+ *
+ * This sanity check is now done in the core timekeeping code.
+ * checking the result of read_tsc() - cycle_last for being negative.
+ * That works because CLOCKSOURCE_MASK(64) does not mask out any bit.
*/
static cycle_t read_tsc(struct clocksource *cs)
{
- cycle_t ret = (cycle_t)get_cycles();
-
- return ret >= clocksource_tsc.cycle_last ?
- ret : clocksource_tsc.cycle_last;
-}
-
-static void resume_tsc(struct clocksource *cs)
-{
- if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC_S3))
- clocksource_tsc.cycle_last = 0;
+ return (cycle_t)get_cycles();
}
+/*
+ * .mask MUST be CLOCKSOURCE_MASK(64). See comment above read_tsc()
+ */
static struct clocksource clocksource_tsc = {
.name = "tsc",
.rating = 300,
.read = read_tsc,
- .resume = resume_tsc,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
CLOCK_SOURCE_MUST_VERIFY,
diff --git a/arch/x86/kernel/vsyscall_gtod.c b/arch/x86/kernel/vsyscall_gtod.c
index 9531fbb123ba..c7d791f32b98 100644
--- a/arch/x86/kernel/vsyscall_gtod.c
+++ b/arch/x86/kernel/vsyscall_gtod.c
@@ -31,29 +31,30 @@ void update_vsyscall(struct timekeeper *tk)
gtod_write_begin(vdata);
/* copy vsyscall data */
- vdata->vclock_mode = tk->clock->archdata.vclock_mode;
- vdata->cycle_last = tk->clock->cycle_last;
- vdata->mask = tk->clock->mask;
- vdata->mult = tk->mult;
- vdata->shift = tk->shift;
+ vdata->vclock_mode = tk->tkr.clock->archdata.vclock_mode;
+ vdata->cycle_last = tk->tkr.cycle_last;
+ vdata->mask = tk->tkr.mask;
+ vdata->mult = tk->tkr.mult;
+ vdata->shift = tk->tkr.shift;
vdata->wall_time_sec = tk->xtime_sec;
- vdata->wall_time_snsec = tk->xtime_nsec;
+ vdata->wall_time_snsec = tk->tkr.xtime_nsec;
vdata->monotonic_time_sec = tk->xtime_sec
+ tk->wall_to_monotonic.tv_sec;
- vdata->monotonic_time_snsec = tk->xtime_nsec
+ vdata->monotonic_time_snsec = tk->tkr.xtime_nsec
+ ((u64)tk->wall_to_monotonic.tv_nsec
- << tk->shift);
+ << tk->tkr.shift);
while (vdata->monotonic_time_snsec >=
- (((u64)NSEC_PER_SEC) << tk->shift)) {
+ (((u64)NSEC_PER_SEC) << tk->tkr.shift)) {
vdata->monotonic_time_snsec -=
- ((u64)NSEC_PER_SEC) << tk->shift;
+ ((u64)NSEC_PER_SEC) << tk->tkr.shift;
vdata->monotonic_time_sec++;
}
vdata->wall_time_coarse_sec = tk->xtime_sec;
- vdata->wall_time_coarse_nsec = (long)(tk->xtime_nsec >> tk->shift);
+ vdata->wall_time_coarse_nsec = (long)(tk->tkr.xtime_nsec >>
+ tk->tkr.shift);
vdata->monotonic_time_coarse_sec =
vdata->wall_time_coarse_sec + tk->wall_to_monotonic.tv_sec;