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Subject[PATCH v7 28/28] coresight: Add support for v8.4 SelfHosted tracing
Date
From: Jonathan Zhou <jonathan.zhouwen@huawei.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@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Jonathan Zhou <jonathan.zhouwen@huawei.com>
[ Move the trace filtering setup etm_init_arch_data() and
clean ups]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
.../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 3d3165dd09d4..18c1a80abab8 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)
--
2.24.1
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