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, rjw@rjwysocki.net, 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 v3 7/7] clocksource/drivers/arm_arch_timer: validate arch_timer_rate Date: Tue, 11 Feb 2020 18:45:42 +0000 [thread overview] Message-ID: <20200211184542.29585-8-ionela.voinescu@arm.com> (raw) In-Reply-To: <20200211184542.29585-1-ionela.voinescu@arm.com> From: Valentin Schneider <valentin.schneider@arm.com> Using an arch timer with a frequency of less than 1MHz can result in an incorrect functionality of the system which assumes a reasonable rate. One example is the use of activity monitors for frequency invariance which uses the rate of the arch timer as the known rate of the constant cycle counter in computing its ratio compared to the maximum frequency of a CPU. For arch timer frequencies less than 1MHz this ratio could end up being 0 which is an invalid value for its use. Therefore, warn if the arch timer rate is below 1MHz which contravenes the recommended architecture interval of 1 to 50MHz. Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com> 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
WARNING: multiple messages have this Message-ID (diff)
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, rjw@rjwysocki.net, ionela.voinescu@arm.com Cc: linux-doc@vger.kernel.org, peterz@infradead.org, viresh.kumar@linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 7/7] clocksource/drivers/arm_arch_timer: validate arch_timer_rate Date: Tue, 11 Feb 2020 18:45:42 +0000 [thread overview] Message-ID: <20200211184542.29585-8-ionela.voinescu@arm.com> (raw) In-Reply-To: <20200211184542.29585-1-ionela.voinescu@arm.com> From: Valentin Schneider <valentin.schneider@arm.com> Using an arch timer with a frequency of less than 1MHz can result in an incorrect functionality of the system which assumes a reasonable rate. One example is the use of activity monitors for frequency invariance which uses the rate of the arch timer as the known rate of the constant cycle counter in computing its ratio compared to the maximum frequency of a CPU. For arch timer frequencies less than 1MHz this ratio could end up being 0 which is an invalid value for its use. Therefore, warn if the arch timer rate is below 1MHz which contravenes the recommended architecture interval of 1 to 50MHz. Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com> 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-02-11 18:46 UTC|newest] Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-02-11 18:45 [PATCH v3 0/7] arm64: ARMv8.4 Activity Monitors support Ionela Voinescu 2020-02-11 18:45 ` Ionela Voinescu 2020-02-11 18:45 ` [PATCH v3 1/7] arm64: add support for the AMU extension v1 Ionela Voinescu 2020-02-11 18:45 ` Ionela Voinescu 2020-02-12 11:30 ` Suzuki Kuruppassery Poulose 2020-02-12 11:30 ` Suzuki Kuruppassery Poulose 2020-02-12 14:54 ` Valentin Schneider 2020-02-12 14:54 ` Valentin Schneider 2020-02-12 16:10 ` Ionela Voinescu 2020-02-12 16:10 ` Ionela Voinescu 2020-02-12 16:20 ` Suzuki Kuruppassery Poulose 2020-02-12 16:20 ` Suzuki Kuruppassery Poulose 2020-02-12 18:20 ` Ionela Voinescu 2020-02-12 18:20 ` Ionela Voinescu 2020-02-12 19:24 ` Suzuki K Poulose 2020-02-12 19:24 ` Suzuki K Poulose 2020-02-12 20:19 ` Ionela Voinescu 2020-02-12 20:19 ` Ionela Voinescu 2020-02-12 16:24 ` Vladimir Murzin 2020-02-12 16:24 ` Vladimir Murzin 2020-02-12 18:27 ` Ionela Voinescu 2020-02-12 18:27 ` Ionela Voinescu 2020-02-11 18:45 ` [PATCH v3 2/7] arm64: trap to EL1 accesses to AMU counters from EL0 Ionela Voinescu 2020-02-11 18:45 ` Ionela Voinescu 2020-02-12 11:44 ` Suzuki Kuruppassery Poulose 2020-02-12 11:44 ` Suzuki Kuruppassery Poulose 2020-02-12 15:36 ` Valentin Schneider 2020-02-12 15:36 ` Valentin Schneider 2020-02-11 18:45 ` [PATCH v3 3/7] arm64/kvm: disable access to AMU registers from kvm guests Ionela Voinescu 2020-02-11 18:45 ` Ionela Voinescu 2020-02-12 15:36 ` Valentin Schneider 2020-02-12 15:36 ` Valentin Schneider 2020-02-12 16:33 ` Suzuki Kuruppassery Poulose 2020-02-12 16:33 ` Suzuki Kuruppassery Poulose 2020-02-11 18:45 ` [PATCH v3 4/7] Documentation: arm64: document support for the AMU extension Ionela Voinescu 2020-02-11 18:45 ` Ionela Voinescu 2020-02-12 15:36 ` Valentin Schneider 2020-02-12 15:36 ` Valentin Schneider 2020-02-11 18:45 ` [PATCH v3 5/7] cpufreq: add function to get the hardware max frequency Ionela Voinescu 2020-02-11 18:45 ` Ionela Voinescu 2020-02-12 4:14 ` Viresh Kumar 2020-02-12 4:14 ` Viresh Kumar 2020-02-13 11:59 ` Valentin Schneider 2020-02-13 11:59 ` Valentin Schneider 2020-02-13 12:59 ` Ionela Voinescu 2020-02-13 12:59 ` Ionela Voinescu 2020-02-13 15:22 ` Valentin Schneider 2020-02-13 15:22 ` Valentin Schneider 2020-02-11 18:45 ` [PATCH v3 6/7] arm64: use activity monitors for frequency invariance Ionela Voinescu 2020-02-11 18:45 ` Ionela Voinescu 2020-02-12 18:59 ` Lukasz Luba 2020-02-12 18:59 ` Lukasz Luba 2020-02-13 9:47 ` Ionela Voinescu 2020-02-13 9:47 ` Ionela Voinescu 2020-02-17 16:59 ` Valentin Schneider 2020-02-17 16:59 ` Valentin Schneider 2020-02-23 18:49 ` Ionela Voinescu 2020-02-23 18:49 ` Ionela Voinescu 2020-02-11 18:45 ` Ionela Voinescu [this message] 2020-02-11 18:45 ` [PATCH v3 7/7] clocksource/drivers/arm_arch_timer: validate arch_timer_rate Ionela Voinescu 2020-02-12 9:30 ` Valentin Schneider 2020-02-12 9:30 ` Valentin Schneider 2020-02-12 10:32 ` Ionela Voinescu 2020-02-12 10:32 ` Ionela Voinescu 2020-02-12 10:01 ` Lukasz Luba 2020-02-12 10:01 ` Lukasz Luba 2020-02-12 10:12 ` Marc Zyngier 2020-02-12 10:12 ` Marc Zyngier 2020-02-12 10:54 ` Ionela Voinescu 2020-02-12 10:54 ` Ionela Voinescu 2020-02-12 10:55 ` Lukasz Luba 2020-02-12 10:55 ` Lukasz Luba 2020-02-12 11:10 ` Marc Zyngier 2020-02-12 11:10 ` Marc Zyngier 2020-02-12 11:43 ` Lukasz Luba 2020-02-12 11:43 ` Lukasz Luba 2020-02-12 11:12 ` Valentin Schneider 2020-02-12 11:12 ` Valentin Schneider 2020-02-14 0:35 ` Thomas Gleixner 2020-02-14 0:35 ` Thomas Gleixner 2020-02-14 15:45 ` Ionela Voinescu 2020-02-14 15:45 ` Ionela Voinescu 2020-02-14 15:57 ` Ionela Voinescu 2020-02-14 15:57 ` Ionela Voinescu
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