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x86/tsc: Add clocksource ID, set system_counterval_t.cs_id

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Add a clocksource ID for TSC and a distinct one for the early TSC.

Use distinct IDs for TSC and early TSC, since those also have distinct
clocksource structs. This should help to keep existing semantics when
comparing clocksources.

Also, set the recently added struct system_counterval_t member cs_id to the
TSC ID in the cases where the clocksource member is being set to the TSC
clocksource. In the future, get_device_system_crosststamp() will compare
the clocksource ID in struct system_counterval_t, rather than the
clocksource.

For the x86 ART related code, system_counterval_t.cs == NULL corresponds to
system_counterval_t.cs_id == CSID_GENERIC (0).

Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240201010453.2212371-4-peter.hilber@opensynergy.com
This commit is contained in:
Peter Hilber 2024-02-01 02:04:48 +01:00 committed by Thomas Gleixner
parent 93630d6df7
commit a2c1fe7206
2 changed files with 23 additions and 7 deletions
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28
arch/x86/kernel/tsc.c
View File

@ -54,6 +54,7 @@ static u32 art_to_tsc_numerator;
static u32 art_to_tsc_denominator;
static u64 art_to_tsc_offset;
static struct clocksource *art_related_clocksource;
static bool have_art;
struct cyc2ns {
struct cyc2ns_data data[2]; /* 0 + 2*16 = 32 */
@ -1168,6 +1169,7 @@ static struct clocksource clocksource_tsc_early = {
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
CLOCK_SOURCE_MUST_VERIFY,
.id = CSID_X86_TSC_EARLY,
.vdso_clock_mode = VDSO_CLOCKMODE_TSC,
.enable = tsc_cs_enable,
.resume = tsc_resume,
@ -1190,6 +1192,7 @@ static struct clocksource clocksource_tsc = {
CLOCK_SOURCE_VALID_FOR_HRES |
CLOCK_SOURCE_MUST_VERIFY |
CLOCK_SOURCE_VERIFY_PERCPU,
.id = CSID_X86_TSC,
.vdso_clock_mode = VDSO_CLOCKMODE_TSC,
.enable = tsc_cs_enable,
.resume = tsc_resume,
@ -1309,8 +1312,11 @@ struct system_counterval_t convert_art_to_tsc(u64 art)
do_div(tmp, art_to_tsc_denominator);
res += tmp + art_to_tsc_offset;
return (struct system_counterval_t) {.cs = art_related_clocksource,
.cycles = res};
return (struct system_counterval_t) {
.cs = art_related_clocksource,
.cs_id = have_art ? CSID_X86_TSC : CSID_GENERIC,
.cycles = res,
};
}
EXPORT_SYMBOL(convert_art_to_tsc);
@ -1327,9 +1333,10 @@ EXPORT_SYMBOL(convert_art_to_tsc);
* that this flag is set before conversion to TSC is attempted.
*
* Return:
* struct system_counterval_t - system counter value with the pointer to the
* struct system_counterval_t - system counter value with the ID of the
* corresponding clocksource:
* cycles: System counter value
* cs_id: The clocksource ID for validating comparability
* cs: Clocksource corresponding to system counter value. Used
* by timekeeping code to verify comparability of two cycle
* values.
@ -1347,8 +1354,11 @@ struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns)
do_div(tmp, USEC_PER_SEC);
res += tmp;
return (struct system_counterval_t) { .cs = art_related_clocksource,
.cycles = res};
return (struct system_counterval_t) {
.cs = art_related_clocksource,
.cs_id = have_art ? CSID_X86_TSC : CSID_GENERIC,
.cycles = res,
};
}
EXPORT_SYMBOL(convert_art_ns_to_tsc);
@ -1454,8 +1464,10 @@ out:
if (tsc_unstable)
goto unreg;
if (boot_cpu_has(X86_FEATURE_ART))
if (boot_cpu_has(X86_FEATURE_ART)) {
art_related_clocksource = &clocksource_tsc;
have_art = true;
}
clocksource_register_khz(&clocksource_tsc, tsc_khz);
unreg:
clocksource_unregister(&clocksource_tsc_early);
@ -1480,8 +1492,10 @@ static int __init init_tsc_clocksource(void)
* the refined calibration and directly register it as a clocksource.
*/
if (boot_cpu_has(X86_FEATURE_TSC_KNOWN_FREQ)) {
if (boot_cpu_has(X86_FEATURE_ART))
if (boot_cpu_has(X86_FEATURE_ART)) {
art_related_clocksource = &clocksource_tsc;
have_art = true;
}
clocksource_register_khz(&clocksource_tsc, tsc_khz);
clocksource_unregister(&clocksource_tsc_early);

2
include/linux/clocksource_ids.h
View File

@ -6,6 +6,8 @@
enum clocksource_ids {
CSID_GENERIC = 0,
CSID_ARM_ARCH_COUNTER,
CSID_X86_TSC_EARLY,
CSID_X86_TSC,
CSID_MAX,
};