linux-kernel - [PATCH 30/31] coresight: Add support for v8.4 SelfHosted tracing

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Message-Id: <20210201181351.1475223-31-mathieu.poirier@linaro.org>
Date:   Mon,  1 Feb 2021 11:13:50 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 30/31] coresight: Add support for v8.4 SelfHosted tracing

From: Jonathan Zhou <jonathan.zhouwen@...wei.com>

v8.4 tracing extensions added support for trace filtering controlled
by TRFCR_ELx. This must be programmed to allow tracing at EL1/EL2 and
EL0. The timestamp used is the virtual time. Also enable CONTEXIDR_EL2
tracing if we are running the kernel at EL2.

Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Mike Leach <mike.leach@...aro.org>
Cc: Will Deacon <will@...nel.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
Signed-off-by: Jonathan Zhou <jonathan.zhouwen@...wei.com>
[ Move the trace filtering setup etm_init_arch_data() and clean ups]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Link: https://lore.kernel.org/r/20210110224850.1880240-29-suzuki.poulose@arm.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
---
 .../coresight/coresight-etm4x-core.c          | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index c6238e208685..473ab7480a36 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -859,6 +859,30 @@ static bool etm4_init_csdev_access(struct etmv4_drvdata *drvdata,
 	return false;
 }
 
+static void cpu_enable_tracing(void)
+{
+	u64 dfr0 = read_sysreg(id_aa64dfr0_el1);
+	u64 trfcr;
+
+	if (!cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_TRACE_FILT_SHIFT))
+		return;
+
+	/*
+	 * If the CPU supports v8.4 SelfHosted Tracing, enable
+	 * tracing at the kernel EL and EL0, forcing to use the
+	 * virtual time as the timestamp.
+	 */
+	trfcr = (TRFCR_ELx_TS_VIRTUAL |
+		 TRFCR_ELx_ExTRE |
+		 TRFCR_ELx_E0TRE);
+
+	/* If we are running at EL2, allow tracing the CONTEXTIDR_EL2. */
+	if (is_kernel_in_hyp_mode())
+		trfcr |= TRFCR_EL2_CX;
+
+	write_sysreg_s(trfcr, SYS_TRFCR_EL1);
+}
+
 static void etm4_init_arch_data(void *info)
 {
 	u32 etmidr0;
@@ -1044,6 +1068,7 @@ static void etm4_init_arch_data(void *info)
 	/* NUMCNTR, bits[30:28] number of counters available for tracing */
 	drvdata->nr_cntr = BMVAL(etmidr5, 28, 30);
 	etm4_cs_lock(drvdata, csa);
+	cpu_enable_tracing();
 }
 
 static inline u32 etm4_get_victlr_access_type(struct etmv4_config *config)
-- 
2.25.1