linux-kernel - [tip: sched/core] loongarch: Provide noinstr sched_clock

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Message-ID: <168599257836.404.16765871891993348111.tip-bot2@tip-bot2>
Date:   Mon, 05 Jun 2023 19:16:18 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Michael Kelley <mikelley@...rosoft.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] loongarch: Provide noinstr sched_clock_read()

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     6b10fef09f937433563822f4bb6a2f947176e5a0
Gitweb:        https://git.kernel.org/tip/6b10fef09f937433563822f4bb6a2f947176e5a0
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Fri, 19 May 2023 12:21:03 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Mon, 05 Jun 2023 21:11:05 +02:00

loongarch: Provide noinstr sched_clock_read()

With the intent to provide local_clock_noinstr(), a variant of
local_clock() that's safe to be called from noinstr code (with the
assumption that any such code will already be non-preemptible),
prepare for things by providing a noinstr sched_clock_read() function.

Specifically, preempt_enable_*() calls out to schedule(), which upsets
noinstr validation efforts.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Tested-by: Michael Kelley <mikelley@...rosoft.com>  # Hyper-V
Link: https://lore.kernel.org/r/20230519102715.502547082@infradead.org
---
 arch/loongarch/include/asm/loongarch.h | 2 +-
 arch/loongarch/kernel/time.c           | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
index b3323ab..357ef70 100644
--- a/arch/loongarch/include/asm/loongarch.h
+++ b/arch/loongarch/include/asm/loongarch.h
@@ -1167,7 +1167,7 @@ static __always_inline void iocsr_write64(u64 val, u32 reg)
 
 #ifndef __ASSEMBLY__
 
-static inline u64 drdtime(void)
+static __always_inline u64 drdtime(void)
 {
 	int rID = 0;
 	u64 val = 0;
diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c
index f377e50..c189e03 100644
--- a/arch/loongarch/kernel/time.c
+++ b/arch/loongarch/kernel/time.c
@@ -190,9 +190,9 @@ static u64 read_const_counter(struct clocksource *clk)
 	return drdtime();
 }
 
-static u64 native_sched_clock(void)
+static noinstr u64 sched_clock_read(void)
 {
-	return read_const_counter(NULL);
+	return drdtime();
 }
 
 static struct clocksource clocksource_const = {
@@ -211,7 +211,7 @@ int __init constant_clocksource_init(void)
 
 	res = clocksource_register_hz(&clocksource_const, freq);
 
-	sched_clock_register(native_sched_clock, 64, freq);
+	sched_clock_register(sched_clock_read, 64, freq);
 
 	pr_info("Constant clock source device register\n");