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From: Athira Rajeev <atrajeev@linux.ibm.com>
To: acme@kernel.org, jolsa@kernel.org, adrian.hunter@intel.com,
	maddy@linux.ibm.com, irogers@google.com, namhyung@kernel.org
Cc: linux-perf-users@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	aboorvad@linux.ibm.com, sshegde@linux.ibm.com,
	atrajeev@linux.ibm.com, kjain@linux.ibm.com,
	hbathini@linux.vnet.ibm.com, Aditya.Bodkhe1@ibm.com,
	venkat88@linux.ibm.com
Subject: [PATCH 01/14] powerpc/time: Expose boot_tb via accessor
Date: Fri, 15 Aug 2025 14:03:54 +0530	[thread overview]
Message-ID: <20250815083407.27953-2-atrajeev@linux.ibm.com> (raw)
In-Reply-To: <20250815083407.27953-1-atrajeev@linux.ibm.com>

From: Aboorva Devarajan <aboorvad@linux.ibm.com>

- Define accessor function get_boot_tb() to safely return boot_tb.
- Tag boot_tb as __ro_after_init (only initialized once and never updated).
- Add a debug log to output the boot timebase during initialization.

Signed-off-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
---
 arch/powerpc/include/asm/time.h | 2 ++
 arch/powerpc/kernel/time.c      | 7 ++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
index f8885586efaf..31bb6be4d355 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -29,6 +29,8 @@ extern u64 decrementer_max;
 
 extern void generic_calibrate_decr(void);
 
+extern u64 get_boot_tb(void);
+
 /* Some sane defaults: 125 MHz timebase, 1GHz processor */
 extern unsigned long ppc_proc_freq;
 #define DEFAULT_PROC_FREQ	(DEFAULT_TB_FREQ * 8)
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 8224381c1dba..f5106b90e517 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -137,7 +137,7 @@ EXPORT_SYMBOL_GPL(rtc_lock);
 
 static u64 tb_to_ns_scale __read_mostly;
 static unsigned tb_to_ns_shift __read_mostly;
-static u64 boot_tb __read_mostly;
+static u64 boot_tb __ro_after_init;
 
 extern struct timezone sys_tz;
 static long timezone_offset;
@@ -639,6 +639,10 @@ notrace unsigned long long sched_clock(void)
 	return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
 }
 
+u64 get_boot_tb(void)
+{
+	return boot_tb;
+}
 
 #ifdef CONFIG_PPC_PSERIES
 
@@ -975,6 +979,7 @@ void __init time_init(void)
 	tb_to_ns_shift = shift;
 	/* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
 	boot_tb = get_tb();
+	pr_debug("%s: timebase at boot: %llu\n", __func__, (unsigned long long)boot_tb);
 
 	/* If platform provided a timezone (pmac), we correct the time */
 	if (timezone_offset) {
-- 
2.47.1


  reply	other threads:[~2025-08-15  8:34 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-15  8:33 [PATCH 00/14] Add interface to expose vpa dtl counters via perf Athira Rajeev
2025-08-15  8:33 ` Athira Rajeev [this message]
2025-08-15  8:33 ` [PATCH 02/14] powerpc/vpa_dtl: " Athira Rajeev
2025-08-20 11:53   ` Shrikanth Hegde
2025-09-04  7:25     ` Athira Rajeev
2025-08-15  8:33 ` [PATCH 03/14] docs: ABI: sysfs-bus-event_source-devices-vpa-dtl: Document sysfs event format entries for vpa_dtl pmu Athira Rajeev
2025-08-15  8:33 ` [PATCH 04/14] powerpc/perf/vpa-dtl: Add support to setup and free aux buffer for capturing DTL data Athira Rajeev
2025-08-15  8:33 ` [PATCH 05/14] powerpc/perf/vpa-dtl: Add support to capture DTL data in aux buffer Athira Rajeev
2025-08-15  8:33 ` [PATCH 06/14] powerpc/perf/vpa-dtl: Handle the writing of perf record when aux wake up is needed Athira Rajeev
2025-08-15  8:34 ` [PATCH 07/14] tools/perf: Add basic CONFIG_AUXTRACE support for VPA pmu on powerpc Athira Rajeev
2025-08-27 17:27   ` Adrian Hunter
2025-08-29  8:29     ` Athira Rajeev
2025-08-15  8:34 ` [PATCH 08/14] tools/perf: process auxtrace events and display in perf report -D Athira Rajeev
2025-08-27 17:28   ` Adrian Hunter
2025-08-29  8:31     ` Athira Rajeev
2025-08-15  8:34 ` [PATCH 09/14] tools/perf: Add event name as vpa-dtl of PERF_TYPE_SYNTH type to present DTL samples Athira Rajeev
2025-08-15  8:34 ` [PATCH 10/14] tools/perf: Allocate and setup aux buffer queue to help co-relate with other events across CPU's Athira Rajeev
2025-08-27 17:29   ` Adrian Hunter
2025-08-15  8:34 ` [PATCH 11/14] tools/perf: Process the DTL entries in queue and deliver samples Athira Rajeev
2025-08-27 17:29   ` Adrian Hunter
2025-08-29  8:33     ` Athira Rajeev
2025-08-15  8:34 ` [PATCH 12/14] tools/perf: Add support for printing synth event details via default callback Athira Rajeev
2025-08-27 17:29   ` Adrian Hunter
2025-08-29  8:35     ` Athira Rajeev
2025-08-15  8:34 ` [PATCH 13/14] tools/perf: Enable perf script to present the DTL entries Athira Rajeev
2025-08-27 17:30   ` Adrian Hunter
2025-08-15  8:34 ` [PATCH 14/14] powerpc/perf/vpa-dtl: Add documentation for VPA dispatch trace log PMU Athira Rajeev
2025-08-15 12:17 ` [PATCH 00/14] Add interface to expose vpa dtl counters via perf Venkat Rao Bagalkote
2025-08-15 12:51   ` Athira Rajeev
2025-08-18 14:41 ` tejas05

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