From: Ionela Voinescu <ionela.voinescu@arm.com>
To: catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com,
maz@kernel.org, suzuki.poulose@arm.com, sudeep.holla@arm.com,
lukasz.luba@arm.com, valentin.schneider@arm.com,
dietmar.eggemann@arm.com, rjw@rjwysocki.net,
pkondeti@codeaurora.org, ionela.voinescu@arm.com
Cc: peterz@infradead.org, mingo@redhat.com,
vincent.guittot@linaro.org, viresh.kumar@linaro.org,
linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: [PATCH v6 7/7] clocksource/drivers/arm_arch_timer: validate arch_timer_rate
Date: Thu, 5 Mar 2020 09:06:27 +0000 [thread overview]
Message-ID: <20200305090627.31908-8-ionela.voinescu@arm.com> (raw)
In-Reply-To: <20200305090627.31908-1-ionela.voinescu@arm.com>
Using an arch timer with a frequency of less than 1MHz can potentially
result in incorrect functionality in systems that assume a reasonable
rate of the arch timer of 1 to 50MHz, described as typical in the
architecture specification.
Therefore, warn if the arch timer rate is below 1MHz, which is
considered atypical and worth emphasizing.
Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Suggested-by: Valentin Schneider <valentin.schneider@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
drivers/clocksource/arm_arch_timer.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 9a5464c625b4..4faa930eabf8 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -885,6 +885,17 @@ static int arch_timer_starting_cpu(unsigned int cpu)
return 0;
}
+static int validate_timer_rate(void)
+{
+ if (!arch_timer_rate)
+ return -EINVAL;
+
+ /* Arch timer frequency < 1MHz can cause trouble */
+ WARN_ON(arch_timer_rate < 1000000);
+
+ return 0;
+}
+
/*
* For historical reasons, when probing with DT we use whichever (non-zero)
* rate was probed first, and don't verify that others match. If the first node
@@ -900,7 +911,7 @@ static void arch_timer_of_configure_rate(u32 rate, struct device_node *np)
arch_timer_rate = rate;
/* Check the timer frequency. */
- if (arch_timer_rate == 0)
+ if (validate_timer_rate())
pr_warn("frequency not available\n");
}
@@ -1594,9 +1605,10 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
* CNTFRQ value. This *must* be correct.
*/
arch_timer_rate = arch_timer_get_cntfrq();
- if (!arch_timer_rate) {
+ ret = validate_timer_rate();
+ if (ret) {
pr_err(FW_BUG "frequency not available.\n");
- return -EINVAL;
+ return ret;
}
arch_timer_uses_ppi = arch_timer_select_ppi();
--
2.17.1
next prev parent reply other threads:[~2020-03-05 9:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-05 9:06 [PATCH v6 0/7] arm64: ARMv8.4 Activity Monitors support Ionela Voinescu
2020-03-05 9:06 ` [PATCH v6 1/7] arm64: add support for the AMU extension v1 Ionela Voinescu
2020-03-05 9:06 ` [PATCH v6 2/7] arm64: trap to EL1 accesses to AMU counters from EL0 Ionela Voinescu
2020-03-05 9:06 ` [PATCH v6 3/7] arm64/kvm: disable access to AMU registers from kvm guests Ionela Voinescu
2020-03-05 9:06 ` [PATCH v6 4/7] Documentation: arm64: document support for the AMU extension Ionela Voinescu
2020-03-05 9:06 ` [PATCH v6 5/7] cpufreq: add function to get the hardware max frequency Ionela Voinescu
2020-03-05 9:06 ` [PATCH v6 6/7] arm64: use activity monitors for frequency invariance Ionela Voinescu
2020-03-06 11:53 ` Sudeep Holla
2020-03-05 9:06 ` Ionela Voinescu [this message]
2020-03-06 11:21 ` [PATCH v6 0/7] arm64: ARMv8.4 Activity Monitors support Catalin Marinas
2020-03-09 14:11 ` Ionela Voinescu
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