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authorSuzuki K Poulose <suzuki.poulose@arm.com>2021-02-01 11:13:44 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-02-04 17:00:34 +0100
commitdc1747a716fe91b88691cc8bd35f986a6774fc47 (patch)
tree0b645c8a4d4b9d51be4db5ac1f49db4159a9fe22 /drivers/hwtracing
parent1ab3bb9df5e35183fee8da2b3fb30feda9a53ce9 (diff)
coresight: etm4x: Detect system instructions support
ETM v4.4 onwards adds support for system instruction access to the ETM. Detect the support on an ETM and switch to using the mode when available. Link: https://lore.kernel.org/r/20210110224850.1880240-23-suzuki.poulose@arm.com Cc: Mike Leach <mike.leach@linaro.org> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Link: https://lore.kernel.org/r/20210201181351.1475223-25-mathieu.poirier@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hwtracing')
-rw-r--r--drivers/hwtracing/coresight/coresight-etm4x-core.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 8d644e93de51..48d8e99e31eb 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -782,6 +782,37 @@ static const struct coresight_ops etm4_cs_ops = {
.source_ops = &etm4_source_ops,
};
+static inline bool cpu_supports_sysreg_trace(void)
+{
+ u64 dfr0 = read_sysreg_s(SYS_ID_AA64DFR0_EL1);
+
+ return ((dfr0 >> ID_AA64DFR0_TRACEVER_SHIFT) & 0xfUL) > 0;
+}
+
+static bool etm4_init_sysreg_access(struct etmv4_drvdata *drvdata,
+ struct csdev_access *csa)
+{
+ u32 devarch;
+
+ if (!cpu_supports_sysreg_trace())
+ return false;
+
+ /*
+ * ETMs implementing sysreg access must implement TRCDEVARCH.
+ */
+ devarch = read_etm4x_sysreg_const_offset(TRCDEVARCH);
+ if ((devarch & ETM_DEVARCH_ID_MASK) != ETM_DEVARCH_ETMv4x_ARCH)
+ return false;
+ *csa = (struct csdev_access) {
+ .io_mem = false,
+ .read = etm4x_sysreg_read,
+ .write = etm4x_sysreg_write,
+ };
+
+ drvdata->arch = etm_devarch_to_arch(devarch);
+ return true;
+}
+
static bool etm4_init_iomem_access(struct etmv4_drvdata *drvdata,
struct csdev_access *csa)
{
@@ -812,9 +843,17 @@ static bool etm4_init_iomem_access(struct etmv4_drvdata *drvdata,
static bool etm4_init_csdev_access(struct etmv4_drvdata *drvdata,
struct csdev_access *csa)
{
+ /*
+ * Always choose the memory mapped io, if there is
+ * a memory map to prevent sysreg access on broken
+ * systems.
+ */
if (drvdata->base)
return etm4_init_iomem_access(drvdata, csa);
+ if (etm4_init_sysreg_access(drvdata, csa))
+ return true;
+
return false;
}