From: Suzuki K Poulose <suzuki.poulose@arm.com> To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, will@kernel.org, catalin.marinas@arm.com, mathieu.poirier@linaro.org, mike.leach@linaro.org, leo.yan@linaro.org, anshuman.khandual@arm.com, coresight@lists.linaro.org, maz@kernel.org, james.morse@arm.com, mark.rutland@arm.com, lcherian@marvell.com, Suzuki K Poulose <suzuki.poulose@arm.com> Subject: [PATCH v3 09/16] coresight: trbe: Add infrastructure for Errata handling Date: Fri, 8 Oct 2021 19:28:59 +0100 [thread overview] Message-ID: <20211008182906.1688009-10-suzuki.poulose@arm.com> (raw) In-Reply-To: <20211008182906.1688009-1-suzuki.poulose@arm.com> Add a minimal infrastructure to keep track of the errata affecting the given TRBE instance. Given that we have heterogeneous CPUs, we have to manage the list per-TRBE instance to be able to apply the work around as needed. Thus we will need to check if individual CPUs are affected by the erratum. We rely on the arm64 errata framework for the actual description and the discovery of a given erratum, to keep the Erratum work around at a central place and benefit from the code and the advertisement from the kernel. Though we could reuse the "this_cpu_has_cap()" to apply an erratum work around, it is a bit of a heavy operation, as it must go through the "erratum" detection check on the CPU every time it is called (e.g, scanning through a table of affected MIDRs). Since we need to do this check for every session, may be multiple times (depending on the wrok around), we could save the cycles by caching the affected errata per-CPU instance in the per-CPU struct trbe_cpudata. Since we are only interested in the errata affecting the TRBE driver, we only need to track a very few of them per-CPU. Thus we use a local mapping of the CPUCAP for the erratum to avoid bloating up a bitmap for trbe_cpudata. i.e, each arm64 TRBE erratum bit is assigned a "index" within the driver to track. Each trbe instance updates the list of affected erratum at probe time on the CPU. This makes sure that we can easily access the list of errata on a given TRBE instance without much overhead. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Mike Leach <mike.leach@linaro.org> Cc: Leo Yan <leo.yan@linaro.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> --- Changes since v2: - Automatically define TRBE_ERRATA_MAX - Add some basic sanity check to make sure the new entries are added in order. - Describe the design choice of caching CPU local errata in trbe_cpudata instead of using this_cpu_has_cap() Changes since v1: - Flip the order of args for trbe_has_erratum() - Move erratum detection further down in the sequence --- drivers/hwtracing/coresight/coresight-trbe.c | 58 +++++++++++++++++++- 1 file changed, 57 insertions(+), 1 deletion(-) diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index f8c04c428780..443194114eb3 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -16,6 +16,7 @@ #define pr_fmt(fmt) DRVNAME ": " fmt #include <asm/barrier.h> + #include "coresight-self-hosted-trace.h" #include "coresight-trbe.h" @@ -67,14 +68,43 @@ struct trbe_buf { struct trbe_cpudata *cpudata; }; +/* + * TRBE erratum list + * + * The errata are defined in arm64 generic cpu_errata framework. + * Since the errata work arounds could be applied individually + * to the affected CPUs inside the TRBE driver, we need to know if + * a given CPU is affected by the erratum. Unlike the other erratum + * work arounds, TRBE driver needs to check multiple times during + * a trace session. Thus we need a quicker access to per-CPU + * errata and not issue costly this_cpu_has_cap() everytime. + * We keep a set of the affected errata in trbe_cpudata, per TRBE. + * + * We rely on the corresponding cpucaps to be defined for a given + * TRBE erratum. We map the given cpucap into a TRBE internal number + * to make the tracking of the errata lean. + * + * This helps in : + * - Not duplicating the detection logic + * - Streamlined detection of erratum across the system + */ + +static int trbe_errata_cpucaps[] = { + -1, /* Sentinel, must be the last entry */ +}; + +/* The total number of listed errata in trbe_errata_cpucaps */ +#define TRBE_ERRATA_MAX (ARRAY_SIZE(trbe_errata_cpucaps) - 1) + /* * struct trbe_cpudata: TRBE instance specific data * @trbe_flag - TRBE dirty/access flag support * @trbe_hw_align - Actual TRBE alignment required for TRBPTR_EL1. - * @trbe_align - Software alignment used for the TRBPTR_EL1, + * @trbe_align - Software alignment used for the TRBPTR_EL1 * @cpu - CPU this TRBE belongs to. * @mode - Mode of current operation. (perf/disabled) * @drvdata - TRBE specific drvdata + * @errata - Bit map for the errata on this TRBE. */ struct trbe_cpudata { bool trbe_flag; @@ -84,6 +114,7 @@ struct trbe_cpudata { enum cs_mode mode; struct trbe_buf *buf; struct trbe_drvdata *drvdata; + DECLARE_BITMAP(errata, TRBE_ERRATA_MAX); }; struct trbe_drvdata { @@ -96,6 +127,25 @@ struct trbe_drvdata { struct platform_device *pdev; }; +static void trbe_check_errata(struct trbe_cpudata *cpudata) +{ + int i; + + for (i = 0; i < TRBE_ERRATA_MAX; i++) { + int cap = trbe_errata_cpucaps[i]; + + if (WARN_ON_ONCE(cap < 0)) + return; + if (this_cpu_has_cap(cap)) + set_bit(i, cpudata->errata); + } +} + +static inline bool trbe_has_erratum(struct trbe_cpudata *cpudata, int i) +{ + return (i < TRBE_ERRATA_MAX) && test_bit(i, cpudata->errata); +} + static int trbe_alloc_node(struct perf_event *event) { if (event->cpu == -1) @@ -979,6 +1029,12 @@ static void arm_trbe_probe_cpu(void *info) goto cpu_clear; } + /* + * Run the TRBE erratum checks, now that we know + * this instance is about to be registered. + */ + trbe_check_errata(cpudata); + cpudata->trbe_align = cpudata->trbe_hw_align; cpudata->trbe_flag = get_trbe_flag_update(trbidr); cpudata->cpu = cpu; -- 2.25.4
WARNING: multiple messages have this Message-ID (diff)
From: Suzuki K Poulose <suzuki.poulose@arm.com> To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, will@kernel.org, catalin.marinas@arm.com, mathieu.poirier@linaro.org, mike.leach@linaro.org, leo.yan@linaro.org, anshuman.khandual@arm.com, coresight@lists.linaro.org, maz@kernel.org, james.morse@arm.com, mark.rutland@arm.com, lcherian@marvell.com, Suzuki K Poulose <suzuki.poulose@arm.com> Subject: [PATCH v3 09/16] coresight: trbe: Add infrastructure for Errata handling Date: Fri, 8 Oct 2021 19:28:59 +0100 [thread overview] Message-ID: <20211008182906.1688009-10-suzuki.poulose@arm.com> (raw) In-Reply-To: <20211008182906.1688009-1-suzuki.poulose@arm.com> Add a minimal infrastructure to keep track of the errata affecting the given TRBE instance. Given that we have heterogeneous CPUs, we have to manage the list per-TRBE instance to be able to apply the work around as needed. Thus we will need to check if individual CPUs are affected by the erratum. We rely on the arm64 errata framework for the actual description and the discovery of a given erratum, to keep the Erratum work around at a central place and benefit from the code and the advertisement from the kernel. Though we could reuse the "this_cpu_has_cap()" to apply an erratum work around, it is a bit of a heavy operation, as it must go through the "erratum" detection check on the CPU every time it is called (e.g, scanning through a table of affected MIDRs). Since we need to do this check for every session, may be multiple times (depending on the wrok around), we could save the cycles by caching the affected errata per-CPU instance in the per-CPU struct trbe_cpudata. Since we are only interested in the errata affecting the TRBE driver, we only need to track a very few of them per-CPU. Thus we use a local mapping of the CPUCAP for the erratum to avoid bloating up a bitmap for trbe_cpudata. i.e, each arm64 TRBE erratum bit is assigned a "index" within the driver to track. Each trbe instance updates the list of affected erratum at probe time on the CPU. This makes sure that we can easily access the list of errata on a given TRBE instance without much overhead. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Mike Leach <mike.leach@linaro.org> Cc: Leo Yan <leo.yan@linaro.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> --- Changes since v2: - Automatically define TRBE_ERRATA_MAX - Add some basic sanity check to make sure the new entries are added in order. - Describe the design choice of caching CPU local errata in trbe_cpudata instead of using this_cpu_has_cap() Changes since v1: - Flip the order of args for trbe_has_erratum() - Move erratum detection further down in the sequence --- drivers/hwtracing/coresight/coresight-trbe.c | 58 +++++++++++++++++++- 1 file changed, 57 insertions(+), 1 deletion(-) diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index f8c04c428780..443194114eb3 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -16,6 +16,7 @@ #define pr_fmt(fmt) DRVNAME ": " fmt #include <asm/barrier.h> + #include "coresight-self-hosted-trace.h" #include "coresight-trbe.h" @@ -67,14 +68,43 @@ struct trbe_buf { struct trbe_cpudata *cpudata; }; +/* + * TRBE erratum list + * + * The errata are defined in arm64 generic cpu_errata framework. + * Since the errata work arounds could be applied individually + * to the affected CPUs inside the TRBE driver, we need to know if + * a given CPU is affected by the erratum. Unlike the other erratum + * work arounds, TRBE driver needs to check multiple times during + * a trace session. Thus we need a quicker access to per-CPU + * errata and not issue costly this_cpu_has_cap() everytime. + * We keep a set of the affected errata in trbe_cpudata, per TRBE. + * + * We rely on the corresponding cpucaps to be defined for a given + * TRBE erratum. We map the given cpucap into a TRBE internal number + * to make the tracking of the errata lean. + * + * This helps in : + * - Not duplicating the detection logic + * - Streamlined detection of erratum across the system + */ + +static int trbe_errata_cpucaps[] = { + -1, /* Sentinel, must be the last entry */ +}; + +/* The total number of listed errata in trbe_errata_cpucaps */ +#define TRBE_ERRATA_MAX (ARRAY_SIZE(trbe_errata_cpucaps) - 1) + /* * struct trbe_cpudata: TRBE instance specific data * @trbe_flag - TRBE dirty/access flag support * @trbe_hw_align - Actual TRBE alignment required for TRBPTR_EL1. - * @trbe_align - Software alignment used for the TRBPTR_EL1, + * @trbe_align - Software alignment used for the TRBPTR_EL1 * @cpu - CPU this TRBE belongs to. * @mode - Mode of current operation. (perf/disabled) * @drvdata - TRBE specific drvdata + * @errata - Bit map for the errata on this TRBE. */ struct trbe_cpudata { bool trbe_flag; @@ -84,6 +114,7 @@ struct trbe_cpudata { enum cs_mode mode; struct trbe_buf *buf; struct trbe_drvdata *drvdata; + DECLARE_BITMAP(errata, TRBE_ERRATA_MAX); }; struct trbe_drvdata { @@ -96,6 +127,25 @@ struct trbe_drvdata { struct platform_device *pdev; }; +static void trbe_check_errata(struct trbe_cpudata *cpudata) +{ + int i; + + for (i = 0; i < TRBE_ERRATA_MAX; i++) { + int cap = trbe_errata_cpucaps[i]; + + if (WARN_ON_ONCE(cap < 0)) + return; + if (this_cpu_has_cap(cap)) + set_bit(i, cpudata->errata); + } +} + +static inline bool trbe_has_erratum(struct trbe_cpudata *cpudata, int i) +{ + return (i < TRBE_ERRATA_MAX) && test_bit(i, cpudata->errata); +} + static int trbe_alloc_node(struct perf_event *event) { if (event->cpu == -1) @@ -979,6 +1029,12 @@ static void arm_trbe_probe_cpu(void *info) goto cpu_clear; } + /* + * Run the TRBE erratum checks, now that we know + * this instance is about to be registered. + */ + trbe_check_errata(cpudata); + cpudata->trbe_align = cpudata->trbe_hw_align; cpudata->trbe_flag = get_trbe_flag_update(trbidr); cpudata->cpu = cpu; -- 2.25.4 _______________________________________________ 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:[~2021-10-08 18:29 UTC|newest] Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-08 18:28 [PATCH v3 00/16] arm64: Self-hosted trace related errata workarounds Suzuki K Poulose 2021-10-08 18:28 ` Suzuki K Poulose 2021-10-08 18:28 ` [PATCH v3 01/16] arm64: Add Neoverse-N2, Cortex-A710 CPU part definition Suzuki K Poulose 2021-10-08 18:28 ` Suzuki K Poulose 2021-10-08 18:28 ` [PATCH v3 02/16] arm64: errata: Add detection for TRBE overwrite in FILL mode Suzuki K Poulose 2021-10-08 18:28 ` Suzuki K Poulose 2021-10-08 18:28 ` [PATCH v3 03/16] arm64: errata: Add workaround for TSB flush failures Suzuki K Poulose 2021-10-08 18:28 ` Suzuki K Poulose 2021-10-11 10:20 ` Will Deacon 2021-10-11 10:20 ` Will Deacon 2021-10-08 18:28 ` [PATCH v3 04/16] arm64: errata: Add detection for TRBE write to out-of-range Suzuki K Poulose 2021-10-08 18:28 ` Suzuki K Poulose 2021-10-08 18:28 ` [PATCH v3 05/16] coresight: trbe: Add a helper to calculate the trace generated Suzuki K Poulose 2021-10-08 18:28 ` Suzuki K Poulose 2021-10-08 18:28 ` [PATCH v3 06/16] coresight: trbe: Add a helper to pad a given buffer area Suzuki K Poulose 2021-10-08 18:28 ` Suzuki K Poulose 2021-10-08 18:28 ` [PATCH v3 07/16] coresight: trbe: Decouple buffer base from the hardware base Suzuki K Poulose 2021-10-08 18:28 ` Suzuki K Poulose 2021-10-08 18:28 ` [PATCH v3 08/16] coresight: trbe: Allow driver to choose a different alignment Suzuki K Poulose 2021-10-08 18:28 ` Suzuki K Poulose 2021-10-08 18:28 ` Suzuki K Poulose [this message] 2021-10-08 18:28 ` [PATCH v3 09/16] coresight: trbe: Add infrastructure for Errata handling Suzuki K Poulose 2021-10-08 18:29 ` [PATCH v3 10/16] coresight: trbe: Workaround TRBE errata overwrite in FILL mode Suzuki K Poulose 2021-10-08 18:29 ` Suzuki K Poulose 2021-10-08 18:29 ` [PATCH v3 11/16] coresight: trbe: Add a helper to determine the minimum buffer size Suzuki K Poulose 2021-10-08 18:29 ` Suzuki K Poulose 2021-10-08 18:29 ` [PATCH v3 12/16] coresight: trbe: Make sure we have enough space Suzuki K Poulose 2021-10-08 18:29 ` Suzuki K Poulose 2021-10-08 18:29 ` [PATCH v3 13/16] coresight: trbe: Work around write to out of range Suzuki K Poulose 2021-10-08 18:29 ` Suzuki K Poulose 2021-10-08 18:29 ` [PATCH v3 14/16] arm64: errata: Advertise workaround for TRBE overwrite in FILL mode Suzuki K Poulose 2021-10-08 18:29 ` Suzuki K Poulose 2021-10-08 18:29 ` [PATCH v3 15/16] arm64: errata: Advertise the workaround for TSB flush failures Suzuki K Poulose 2021-10-08 18:29 ` Suzuki K Poulose 2021-10-11 10:18 ` Will Deacon 2021-10-11 10:18 ` Will Deacon 2021-10-11 12:32 ` Suzuki K Poulose 2021-10-11 12:32 ` Suzuki K Poulose 2021-10-08 18:29 ` [PATCH v3 16/16] arm64: errata: Advertise TRBE erratum workaround for write to out-of-range address Suzuki K Poulose 2021-10-08 18:29 ` Suzuki K Poulose
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