From fc804f65d46236c211f530174904c1ed70db5888 Mon Sep 17 00:00:00 2001 From: Rajvi Jingar Date: Thu, 8 Mar 2018 09:28:36 -0800 Subject: x86/tsc: Convert ART in nanoseconds to TSC Device drivers use get_device_system_crosststamp() to produce precise system/device cross-timestamps. The PHC clock and ALSA interfaces, for example, make the cross-timestamps available to user applications. On Intel platforms, get_device_system_crosststamp() requires a TSC value derived from ART (Always Running Timer) to compute the monotonic raw and realtime system timestamps. Starting with Intel Goldmont platforms, the PCIe root complex supports the PTM time sync protocol. PTM requires all timestamps to be in units of nanoseconds. The Intel root complex hardware propagates system time derived from ART in units of nanoseconds performing the conversion as follows: ART_NS = ART * 1e9 / When user software requests a cross-timestamp, the system timestamps (generally read from device registers) must be converted to TSC by the driver software as follows: TSC = ART_NS * TSC_KHZ / 1e6 This is valid when CPU feature flag X86_FEATURE_TSC_KNOWN_FREQ is set indicating that tsc_khz is derived from CPUID[15H]. Drivers should check whether this flag is set before conversion to TSC is attempted. Suggested-by: Christopher S. Hall Signed-off-by: Rajvi Jingar Signed-off-by: Thomas Gleixner Cc: peterz@infradead.org Link: https://lkml.kernel.org/r/1520530116-4925-1-git-send-email-rajvi.jingar@intel.com --- arch/x86/include/asm/tsc.h | 1 + arch/x86/kernel/tsc.c | 39 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+) diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h index cf5d53c3f9ea..2701d221583a 100644 --- a/arch/x86/include/asm/tsc.h +++ b/arch/x86/include/asm/tsc.h @@ -31,6 +31,7 @@ static inline cycles_t get_cycles(void) } extern struct system_counterval_t convert_art_to_tsc(u64 art); +extern struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns); extern void tsc_early_delay_calibrate(void); extern void tsc_init(void); diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index fb4302738410..ef32297ff17e 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -1179,6 +1179,45 @@ struct system_counterval_t convert_art_to_tsc(u64 art) } EXPORT_SYMBOL(convert_art_to_tsc); +/** + * convert_art_ns_to_tsc() - Convert ART in nanoseconds to TSC. + * @art_ns: ART (Always Running Timer) in unit of nanoseconds + * + * PTM requires all timestamps to be in units of nanoseconds. When user + * software requests a cross-timestamp, this function converts system timestamp + * to TSC. + * + * This is valid when CPU feature flag X86_FEATURE_TSC_KNOWN_FREQ is set + * indicating the tsc_khz is derived from CPUID[15H]. Drivers should check + * that this flag is set before conversion to TSC is attempted. + * + * Return: + * struct system_counterval_t - system counter value with the pointer to the + * corresponding clocksource + * @cycles: System counter value + * @cs: Clocksource corresponding to system counter value. Used + * by timekeeping code to verify comparibility of two cycle + * values. + */ + +struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns) +{ + u64 tmp, res, rem; + + rem = do_div(art_ns, USEC_PER_SEC); + + res = art_ns * tsc_khz; + tmp = rem * tsc_khz; + + do_div(tmp, USEC_PER_SEC); + res += tmp; + + return (struct system_counterval_t) { .cs = art_related_clocksource, + .cycles = res}; +} +EXPORT_SYMBOL(convert_art_ns_to_tsc); + + static void tsc_refine_calibration_work(struct work_struct *work); static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work); /** -- cgit v1.2.3 From ea89c065482179b2bf9f9b6788b06a6e0c68a73b Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 23 Mar 2018 00:05:29 +0100 Subject: x86/tsc: Get rid of rdtscll() Commit 99770737ca7e ("x86/asm/tsc: Add rdtscll() merge helper") added rdtscll() in August 2015 along with the comment: /* Deprecated, keep it for a cycle for easier merging: */ 12 cycles later it's really overdue for removal. Signed-off-by: Thomas Gleixner --- arch/x86/events/msr.c | 3 ++- arch/x86/include/asm/msr.h | 3 --- arch/x86/kernel/cpu/mcheck/mce-inject.c | 2 +- 3 files changed, 3 insertions(+), 5 deletions(-) diff --git a/arch/x86/events/msr.c b/arch/x86/events/msr.c index 18e2628e2d8f..e7edf19e64c2 100644 --- a/arch/x86/events/msr.c +++ b/arch/x86/events/msr.c @@ -188,10 +188,11 @@ static inline u64 msr_read_counter(struct perf_event *event) if (event->hw.event_base) rdmsrl(event->hw.event_base, now); else - rdtscll(now); + now = rdtsc_ordered(); return now; } + static void msr_event_update(struct perf_event *event) { u64 prev, now; diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h index 30df295f6d94..392f05d57e78 100644 --- a/arch/x86/include/asm/msr.h +++ b/arch/x86/include/asm/msr.h @@ -218,9 +218,6 @@ static __always_inline unsigned long long rdtsc_ordered(void) return rdtsc(); } -/* Deprecated, keep it for a cycle for easier merging: */ -#define rdtscll(now) do { (now) = rdtsc_ordered(); } while (0) - static inline unsigned long long native_read_pmc(int counter) { DECLARE_ARGS(val, low, high); diff --git a/arch/x86/kernel/cpu/mcheck/mce-inject.c b/arch/x86/kernel/cpu/mcheck/mce-inject.c index 231ad23b24a9..475cb4f5f14f 100644 --- a/arch/x86/kernel/cpu/mcheck/mce-inject.c +++ b/arch/x86/kernel/cpu/mcheck/mce-inject.c @@ -491,7 +491,7 @@ static void do_inject(void) unsigned int cpu = i_mce.extcpu; u8 b = i_mce.bank; - rdtscll(i_mce.tsc); + i_mce.tsc = rdtsc_ordered(); if (i_mce.misc) i_mce.status |= MCI_STATUS_MISCV; -- cgit v1.2.3