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 <[email protected]>
---
Notes:
v3:
- Omit redundant clocksource_ids.h include (Andy Shevchenko).
- Omit struct system_counterval_t member documentation, to resolve
kernel-doc warning pointed out by Simon Horman.
v2:
- Name clock id according to Thomas Gleixner's mockup.
- Refer to clocksource IDs as such in comments (Thomas Gleixner).
- Update comments which were still referring to clocksource pointers.
arch/x86/kernel/tsc.c | 27 ++++++++++++++++++++-------
include/linux/clocksource_ids.h | 2 ++
2 files changed, 22 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 42328f9653c1..9f164aad5e94 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -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);
@@ -1327,7 +1333,7 @@ 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
*/
@@ -1343,8 +1349,11 @@ 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);
@@ -1450,8 +1459,10 @@ static void tsc_refine_calibration_work(struct work_struct *work)
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);
@@ -1476,8 +1487,10 @@ 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);
diff --git a/include/linux/clocksource_ids.h b/include/linux/clocksource_ids.h
index 16775d7d8f8d..f8467946e9ee 100644
--- a/include/linux/clocksource_ids.h
+++ b/include/linux/clocksource_ids.h
@@ -6,6 +6,8 @@
enum clocksource_ids {
CSID_GENERIC = 0,
CSID_ARM_ARCH_COUNTER,
+ CSID_X86_TSC_EARLY,
+ CSID_X86_TSC,
CSID_MAX,
};
--
2.40.1
The following commit has been merged into the timers/ptp branch of tip:
Commit-ID: a2c1fe72062a5dd69de4dfe892f6436d6c0479dd
Gitweb: https://git.kernel.org/tip/a2c1fe72062a5dd69de4dfe892f6436d6c0479dd
Author: Peter Hilber <[email protected]>
AuthorDate: Thu, 01 Feb 2024 02:04:48 +01:00
Committer: Thomas Gleixner <[email protected]>
CommitterDate: Wed, 07 Feb 2024 17:05:21 +01:00
x86/tsc: Add clocksource ID, set system_counterval_t.cs_id
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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
arch/x86/kernel/tsc.c | 28 +++++++++++++++++++++-------
include/linux/clocksource_ids.h | 2 ++
2 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 7978f31..fd567a0 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -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);
diff --git a/include/linux/clocksource_ids.h b/include/linux/clocksource_ids.h
index 16775d7..f846794 100644
--- a/include/linux/clocksource_ids.h
+++ b/include/linux/clocksource_ids.h
@@ -6,6 +6,8 @@
enum clocksource_ids {
CSID_GENERIC = 0,
CSID_ARM_ARCH_COUNTER,
+ CSID_X86_TSC_EARLY,
+ CSID_X86_TSC,
CSID_MAX,
};