coresight: etm4x: Add support for PE OS lock

mainline inclusion
from mainline-v5.12-rc3
commit bc2c689f
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5YCYK
CVE: NA

Reference: https://lore.kernel.org/r/20210405164307.1720226-12-suzuki.poulose@arm.com

--------------------------------------------------------------------------

ETE may not implement the OS lock and instead could rely on
the PE OS Lock for the trace unit access. This is indicated
by the TRCOLSR.OSM == 0b100. Add support for handling the
PE OS lock

Cc: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Nmike.leach <mike.leach@linaro.org>
Signed-off-by: NSuzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20210405164307.1720226-12-suzuki.poulose@arm.comSigned-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>

drivers/hwtracing/coresight/coresight-etm4x-core.c

@@ -131,30 +131,59 @@ static void ete_sysreg_write(u64 val, u32 offset, bool _relaxed, bool _64bit)
 	}
 }
 
-static void etm4_os_unlock_csa(struct etmv4_drvdata *drvdata, struct csdev_access *csa)
+static void etm_detect_os_lock(struct etmv4_drvdata *drvdata,
+			       struct csdev_access *csa)
 {
-	/* Writing 0 to TRCOSLAR unlocks the trace registers */
-	etm4x_relaxed_write32(csa, 0x0, TRCOSLAR);
-	drvdata->os_unlock = true;
+	u32 oslsr = etm4x_relaxed_read32(csa, TRCOSLSR);
+
+	drvdata->os_lock_model = ETM_OSLSR_OSLM(oslsr);
+}
+
+static void etm_write_os_lock(struct etmv4_drvdata *drvdata,
+			      struct csdev_access *csa, u32 val)
+{
+	val = !!val;
+
+	switch (drvdata->os_lock_model) {
+	case ETM_OSLOCK_PRESENT:
+		etm4x_relaxed_write32(csa, val, TRCOSLAR);
+		break;
+	case ETM_OSLOCK_PE:
+		write_sysreg_s(val, SYS_OSLAR_EL1);
+		break;
+	default:
+		pr_warn_once("CPU%d: Unsupported Trace OSLock model: %x\n",
+			     smp_processor_id(), drvdata->os_lock_model);
+		fallthrough;
+	case ETM_OSLOCK_NI:
+		return;
+	}
 	isb();
 }
 
+static inline void etm4_os_unlock_csa(struct etmv4_drvdata *drvdata,
+				      struct csdev_access *csa)
+{
+	WARN_ON(drvdata->cpu != smp_processor_id());
+
+	/* Writing 0 to OS Lock unlocks the trace unit registers */
+	etm_write_os_lock(drvdata, csa, 0x0);
+	drvdata->os_unlock = true;
+}
+
 static void etm4_os_unlock(struct etmv4_drvdata *drvdata)
 {
 	if (!WARN_ON(!drvdata->csdev))
 		etm4_os_unlock_csa(drvdata, &drvdata->csdev->access);
-
 }
 
 static void etm4_os_lock(struct etmv4_drvdata *drvdata)
 {
 	if (WARN_ON(!drvdata->csdev))
 		return;
-
-	/* Writing 0x1 to TRCOSLAR locks the trace registers */
-	etm4x_relaxed_write32(&drvdata->csdev->access, 0x1, TRCOSLAR);
+	/* Writing 0x1 to OS Lock locks the trace registers */
+	etm_write_os_lock(drvdata, &drvdata->csdev->access, 0x1);
 	drvdata->os_unlock = false;
-	isb();
 }
 
 static void etm4_cs_lock(struct etmv4_drvdata *drvdata,
@@ -1012,9 +1041,11 @@ static void etm4_init_arch_data(void *info)
 	if (!etm4_init_csdev_access(drvdata, csa))
 		return;
 
+	/* Detect the support for OS Lock before we actually use it */
+	etm_detect_os_lock(drvdata, csa);
 
 	/* Make sure all registers are accessible */
-	etm4_os_unlock(drvdata);
+	etm4_os_unlock_csa(drvdata, csa);
 	etm4_cs_unlock(drvdata, csa);
 
 	/* find all capabilities of the tracing unit */

drivers/hwtracing/coresight/coresight-etm4x.h

@@ -538,6 +538,20 @@
 					 ETM_MODE_EXCL_KERN | \
 					 ETM_MODE_EXCL_USER)
 
+/*
+ * TRCOSLSR.OSLM advertises the OS Lock model.
+ * OSLM[2:0] = TRCOSLSR[4:3,0]
+ *
+ *	0b000 - Trace OS Lock is not implemented.
+ *	0b010 - Trace OS Lock is implemented.
+ *	0b100 - Trace OS Lock is not implemented, unit is controlled by PE OS Lock.
+ */
+#define ETM_OSLOCK_NI		0b000
+#define ETM_OSLOCK_PRESENT	0b010
+#define ETM_OSLOCK_PE		0b100
+
+#define ETM_OSLSR_OSLM(oslsr)	((((oslsr) & GENMASK(4, 3)) >> 2) | (oslsr & 0x1))
+
 /*
  * TRCDEVARCH Bit field definitions
  * Bits[31:21]	- ARCHITECT = Always Arm Ltd.
@@ -922,6 +936,7 @@ struct etmv4_drvdata {
 	u8				s_ex_level;
 	u8				ns_ex_level;
 	u8				q_support;
+	u8				os_lock_model;
 	bool				sticky_enable;
 	bool				boot_enable;
 	bool				os_unlock;