linux-kernel - [PATCH 2/3] x86/tsc: Add set_tsc_system

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Date:   Mon, 23 Jan 2023 10:27:27 -0800
From:   kan.liang@...ux.intel.com
To:     peterz@...radead.org, mingo@...hat.com, tglx@...utronix.de,
        jstultz@...gle.com, sboyd@...nel.org, linux-kernel@...r.kernel.org
Cc:     eranian@...gle.com, namhyung@...nel.org, ak@...ux.intel.com,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH 2/3] x86/tsc: Add set_tsc_system_counterval

From: Kan Liang <kan.liang@...ux.intel.com>

The perf_event subsystem wants to convert a TSC of a PEBS record to a
monotonic clock. Introduce a new function to provide both the TSC
value and TSC clocksource information with the format required by the
callback function from the timekeeping code.

Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 arch/x86/include/asm/tsc.h | 1 +
 arch/x86/kernel/tsc.c      | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index fbdc3d951494..45aac88b5ce4 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -29,6 +29,7 @@ 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 struct system_counterval_t set_tsc_system_counterval(u64 tsc);
 
 extern void tsc_early_init(void);
 extern void tsc_init(void);
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index a78e73da4a74..45803e65630e 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1311,6 +1311,12 @@ struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns)
 }
 EXPORT_SYMBOL(convert_art_ns_to_tsc);
 
+struct system_counterval_t set_tsc_system_counterval(u64 tsc)
+{
+	return (struct system_counterval_t) { .cs = &clocksource_tsc,
+					      .cycles = tsc};
+}
+EXPORT_SYMBOL(set_tsc_system_counterval);
 
 static void tsc_refine_calibration_work(struct work_struct *work);
 static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work);
-- 
2.35.1