arm-bsp/tc: enable tracing in Total Compute

Message ID 20220203154345.36540-1-davidson.kumaresan@arm.com
State New
Headers show
Series arm-bsp/tc: enable tracing in Total Compute | expand

Commit Message

Davidson Kumaresan Feb. 3, 2022, 3:43 p.m. UTC
Enable coresight components in the config and also port the patches
which were upstreamed in later version of the linux kernel.

Change-Id: I27983abd5f2945328f7465cc1b2af4f8e848b69b
Signed-off-by: Davidson K <davidson.kumaresan@arm.com>
---
 .../bsp/arm-platforms/tc.scc                  |   1 +
 .../bsp/arm-platforms/tc/autofdo.cfg          |   3 +
 .../linux/linux-arm-platforms.inc             |   2 +
 ...resight-etm4x-Save-restore-TRFCR_EL1.patch | 181 ++++++++++++++
 ...Use-Trace-Filtering-controls-dynamic.patch | 227 ++++++++++++++++++
 5 files changed, 414 insertions(+)
 create mode 100644 meta-arm-bsp/recipes-kernel/linux/arm-platforms-kmeta/bsp/arm-platforms/tc/autofdo.cfg
 create mode 100644 meta-arm-bsp/recipes-kernel/linux/linux-arm64-ack-5.10/tc/0022-coresight-etm4x-Save-restore-TRFCR_EL1.patch
 create mode 100644 meta-arm-bsp/recipes-kernel/linux/linux-arm64-ack-5.10/tc/0023-coresight-etm4x-Use-Trace-Filtering-controls-dynamic.patch

Comments

Jon Mason Feb. 4, 2022, 3:56 a.m. UTC | #1
On Thu, 3 Feb 2022 21:13:45 +0530, Davidson K wrote:
> Enable coresight components in the config and also port the patches
> which were upstreamed in later version of the linux kernel.

Applied, thanks!

[1/1] arm-bsp/tc: enable tracing in Total Compute
      commit: 37ee3eecc521778ab7ead0136c91b92304f43d0f

Best regards,

Patch

diff --git a/meta-arm-bsp/recipes-kernel/linux/arm-platforms-kmeta/bsp/arm-platforms/tc.scc b/meta-arm-bsp/recipes-kernel/linux/arm-platforms-kmeta/bsp/arm-platforms/tc.scc
index 86e450c6..62748e1c 100644
--- a/meta-arm-bsp/recipes-kernel/linux/arm-platforms-kmeta/bsp/arm-platforms/tc.scc
+++ b/meta-arm-bsp/recipes-kernel/linux/arm-platforms-kmeta/bsp/arm-platforms/tc.scc
@@ -5,3 +5,4 @@  kconf non-hardware tc/gralloc.cfg
 kconf non-hardware tc/mali.cfg
 kconf non-hardware tc/tee.cfg
 kconf non-hardware tc/virtio.cfg
+kconf non-hardware tc/autofdo.cfg
diff --git a/meta-arm-bsp/recipes-kernel/linux/arm-platforms-kmeta/bsp/arm-platforms/tc/autofdo.cfg b/meta-arm-bsp/recipes-kernel/linux/arm-platforms-kmeta/bsp/arm-platforms/tc/autofdo.cfg
new file mode 100644
index 00000000..8530c884
--- /dev/null
+++ b/meta-arm-bsp/recipes-kernel/linux/arm-platforms-kmeta/bsp/arm-platforms/tc/autofdo.cfg
@@ -0,0 +1,3 @@ 
+CONFIG_CORESIGHT=y
+CONFIG_CORESIGHT_SOURCE_ETM4X=y
+CONFIG_CORESIGHT_TRBE=y
diff --git a/meta-arm-bsp/recipes-kernel/linux/linux-arm-platforms.inc b/meta-arm-bsp/recipes-kernel/linux/linux-arm-platforms.inc
index 418ea3dd..0f62011c 100644
--- a/meta-arm-bsp/recipes-kernel/linux/linux-arm-platforms.inc
+++ b/meta-arm-bsp/recipes-kernel/linux/linux-arm-platforms.inc
@@ -220,5 +220,7 @@  SRC_URI:append:tc = " \
     file://0018-optee-add-a-FF-A-memory-pool.patch \
     file://0019-optee-add-FF-A-support.patch \
     file://0021-arm_ffa-add-support-for-FFA-v1.1.patch \
+    file://0022-coresight-etm4x-Save-restore-TRFCR_EL1.patch \
+    file://0023-coresight-etm4x-Use-Trace-Filtering-controls-dynamic.patch \
     "
 KERNEL_FEATURES:append:tc = " bsp/arm-platforms/tc.scc"
diff --git a/meta-arm-bsp/recipes-kernel/linux/linux-arm64-ack-5.10/tc/0022-coresight-etm4x-Save-restore-TRFCR_EL1.patch b/meta-arm-bsp/recipes-kernel/linux/linux-arm64-ack-5.10/tc/0022-coresight-etm4x-Save-restore-TRFCR_EL1.patch
new file mode 100644
index 00000000..e67658fa
--- /dev/null
+++ b/meta-arm-bsp/recipes-kernel/linux/linux-arm64-ack-5.10/tc/0022-coresight-etm4x-Save-restore-TRFCR_EL1.patch
@@ -0,0 +1,181 @@ 
+From 7150eac72ee0c2c7da03f53a90a871c3d6d4e538 Mon Sep 17 00:00:00 2001
+From: Suzuki K Poulose <suzuki.poulose@arm.com>
+Date: Tue, 14 Sep 2021 11:26:32 +0100
+Subject: [PATCH 1/2] coresight: etm4x: Save restore TRFCR_EL1
+
+When the CPU enters a low power mode, the TRFCR_EL1 contents could be
+reset. Thus we need to save/restore the TRFCR_EL1 along with the ETM4x
+registers to allow the tracing.
+
+The TRFCR related helpers are in a new header file, as we need to use
+them for TRBE in the later patches.
+
+Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
+Cc: Anshuman Khandual <anshuman.khandual@arm.com>
+Cc: Mike Leach <mike.leach@linaro.org>
+Cc: Leo Yan <leo.yan@linaro.org>
+Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
+Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
+Link: https://lore.kernel.org/r/20210914102641.1852544-2-suzuki.poulose@arm.com
+[Fixed cosmetic details]
+Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
+
+Upstream-Status: Backport [https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=937d3f58cacf377cab7c32e475e1ffa91d611dce]
+Signed-off-by: Davidson K <davidson.kumaresan@arm.com>
+---
+ .../coresight/coresight-etm4x-core.c          | 43 +++++++++++++------
+ drivers/hwtracing/coresight/coresight-etm4x.h |  2 +
+ .../coresight/coresight-self-hosted-trace.h   | 24 +++++++++++
+ 3 files changed, 57 insertions(+), 12 deletions(-)
+ create mode 100644 drivers/hwtracing/coresight/coresight-self-hosted-trace.h
+
+diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
+index 90827077d2f9..b78080d169f8 100644
+--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
++++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
+@@ -39,6 +39,7 @@
+ 
+ #include "coresight-etm4x.h"
+ #include "coresight-etm-perf.h"
++#include "coresight-self-hosted-trace.h"
+ 
+ static int boot_enable;
+ module_param(boot_enable, int, 0444);
+@@ -990,7 +991,7 @@ static void cpu_enable_tracing(struct etmv4_drvdata *drvdata)
+ 	if (is_kernel_in_hyp_mode())
+ 		trfcr |= TRFCR_EL2_CX;
+ 
+-	write_sysreg_s(trfcr, SYS_TRFCR_EL1);
++	write_trfcr(trfcr);
+ }
+ 
+ static void etm4_init_arch_data(void *info)
+@@ -1528,7 +1529,7 @@ static void etm4_init_trace_id(struct etmv4_drvdata *drvdata)
+ 	drvdata->trcid = coresight_get_trace_id(drvdata->cpu);
+ }
+ 
+-static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
++static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
+ {
+ 	int i, ret = 0;
+ 	struct etmv4_save_state *state;
+@@ -1667,7 +1668,23 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
+ 	return ret;
+ }
+ 
+-static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
++static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
++{
++	int ret = 0;
++
++	/* Save the TRFCR irrespective of whether the ETM is ON */
++	if (drvdata->trfc)
++		drvdata->save_trfcr = read_trfcr();
++	/*
++	 * Save and restore the ETM Trace registers only if
++	 * the ETM is active.
++	 */
++	if (local_read(&drvdata->mode) && drvdata->save_state)
++		ret = __etm4_cpu_save(drvdata);
++	return ret;
++}
++
++static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
+ {
+ 	int i;
+ 	struct etmv4_save_state *state = drvdata->save_state;
+@@ -1763,6 +1780,14 @@ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
+ 	etm4_cs_lock(drvdata, csa);
+ }
+ 
++static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
++{
++	if (drvdata->trfc)
++		write_trfcr(drvdata->save_trfcr);
++	if (drvdata->state_needs_restore)
++		__etm4_cpu_restore(drvdata);
++}
++
+ static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
+ 			      void *v)
+ {
+@@ -1774,23 +1799,17 @@ static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
+ 
+ 	drvdata = etmdrvdata[cpu];
+ 
+-	if (!drvdata->save_state)
+-		return NOTIFY_OK;
+-
+ 	if (WARN_ON_ONCE(drvdata->cpu != cpu))
+ 		return NOTIFY_BAD;
+ 
+ 	switch (cmd) {
+ 	case CPU_PM_ENTER:
+-		/* save the state if self-hosted coresight is in use */
+-		if (local_read(&drvdata->mode))
+-			if (etm4_cpu_save(drvdata))
+-				return NOTIFY_BAD;
++		if (etm4_cpu_save(drvdata))
++			return NOTIFY_BAD;
+ 		break;
+ 	case CPU_PM_EXIT:
+ 	case CPU_PM_ENTER_FAILED:
+-		if (drvdata->state_needs_restore)
+-			etm4_cpu_restore(drvdata);
++		etm4_cpu_restore(drvdata);
+ 		break;
+ 	default:
+ 		return NOTIFY_DONE;
+diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
+index e5b79bdb9851..82cba16b73a6 100644
+--- a/drivers/hwtracing/coresight/coresight-etm4x.h
++++ b/drivers/hwtracing/coresight/coresight-etm4x.h
+@@ -921,6 +921,7 @@ struct etmv4_save_state {
+  * @lpoverride:	If the implementation can support low-power state over.
+  * @trfc:	If the implementation supports Arm v8.4 trace filter controls.
+  * @config:	structure holding configuration parameters.
++ * @save_trfcr:	Saved TRFCR_EL1 register during a CPU PM event.
+  * @save_state:	State to be preserved across power loss
+  * @state_needs_restore: True when there is context to restore after PM exit
+  * @skip_power_up: Indicates if an implementation can skip powering up
+@@ -973,6 +974,7 @@ struct etmv4_drvdata {
+ 	bool				lpoverride;
+ 	bool				trfc;
+ 	struct etmv4_config		config;
++	u64				save_trfcr;
+ 	struct etmv4_save_state		*save_state;
+ 	bool				state_needs_restore;
+ 	bool				skip_power_up;
+diff --git a/drivers/hwtracing/coresight/coresight-self-hosted-trace.h b/drivers/hwtracing/coresight/coresight-self-hosted-trace.h
+new file mode 100644
+index 000000000000..303d71911870
+--- /dev/null
++++ b/drivers/hwtracing/coresight/coresight-self-hosted-trace.h
+@@ -0,0 +1,24 @@
++/* SPDX-License-Identifier: GPL-2.0-only */
++/*
++ * Arm v8 Self-Hosted trace support.
++ *
++ * Copyright (C) 2021 ARM Ltd.
++ */
++
++#ifndef __CORESIGHT_SELF_HOSTED_TRACE_H
++#define __CORESIGHT_SELF_HOSTED_TRACE_H
++
++#include <asm/sysreg.h>
++
++static inline u64 read_trfcr(void)
++{
++	return read_sysreg_s(SYS_TRFCR_EL1);
++}
++
++static inline void write_trfcr(u64 val)
++{
++	write_sysreg_s(val, SYS_TRFCR_EL1);
++	isb();
++}
++
++#endif /*  __CORESIGHT_SELF_HOSTED_TRACE_H */
+-- 
+2.34.1
+
diff --git a/meta-arm-bsp/recipes-kernel/linux/linux-arm64-ack-5.10/tc/0023-coresight-etm4x-Use-Trace-Filtering-controls-dynamic.patch b/meta-arm-bsp/recipes-kernel/linux/linux-arm64-ack-5.10/tc/0023-coresight-etm4x-Use-Trace-Filtering-controls-dynamic.patch
new file mode 100644
index 00000000..4d5a719b
--- /dev/null
+++ b/meta-arm-bsp/recipes-kernel/linux/linux-arm64-ack-5.10/tc/0023-coresight-etm4x-Use-Trace-Filtering-controls-dynamic.patch
@@ -0,0 +1,227 @@ 
+From 55228b0522bfb7d945019a8931742ab9b063b6c9 Mon Sep 17 00:00:00 2001
+From: Suzuki K Poulose <suzuki.poulose@arm.com>
+Date: Tue, 14 Sep 2021 11:26:33 +0100
+Subject: [PATCH 2/2] coresight: etm4x: Use Trace Filtering controls
+ dynamically
+
+The Trace Filtering support (FEAT_TRF) ensures that the ETM
+can be prohibited from generating any trace for a given EL.
+This is much stricter knob, than the TRCVICTLR exception level
+masks, which doesn't prevent the ETM from generating Context
+packets for an "excluded" EL. At the moment, we do a onetime
+enable trace at user and kernel and leave it untouched for the
+kernel life time. This implies that the ETM could potentially
+generate trace packets containing the kernel addresses, and
+thus leaking the kernel virtual address in the trace.
+
+This patch makes the switch dynamic, by honoring the filters
+set by the user and enforcing them in the TRFCR controls.
+We also rename the cpu_enable_tracing() appropriately to
+cpu_detect_trace_filtering() and the drvdata member
+trfc => trfcr to indicate the "value" of the TRFCR_EL1.
+
+Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
+Cc: Al Grant <al.grant@arm.com>
+Cc: Mike Leach <mike.leach@linaro.org>
+Cc: Leo Yan <leo.yan@linaro.org>
+Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
+Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
+Link: https://lore.kernel.org/r/20210914102641.1852544-3-suzuki.poulose@arm.com
+Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
+
+Upstream-Status: Backport [https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5f6fd1aa8cc147b111af1a833574487a87237dc0]
+Signed-off-by: Davidson K <davidson.kumaresan@arm.com>
+---
+ .../coresight/coresight-etm4x-core.c          | 63 ++++++++++++++-----
+ drivers/hwtracing/coresight/coresight-etm4x.h |  7 ++-
+ .../coresight/coresight-self-hosted-trace.h   |  7 +++
+ 3 files changed, 59 insertions(+), 18 deletions(-)
+
+diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
+index b78080d169f8..b804d4413b43 100644
+--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
++++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
+@@ -237,6 +237,45 @@ struct etm4_enable_arg {
+ 	int rc;
+ };
+ 
++/*
++ * etm4x_prohibit_trace - Prohibit the CPU from tracing at all ELs.
++ * When the CPU supports FEAT_TRF, we could move the ETM to a trace
++ * prohibited state by filtering the Exception levels via TRFCR_EL1.
++ */
++static void etm4x_prohibit_trace(struct etmv4_drvdata *drvdata)
++{
++	/* If the CPU doesn't support FEAT_TRF, nothing to do */
++	if (!drvdata->trfcr)
++		return;
++	cpu_prohibit_trace();
++}
++
++/*
++ * etm4x_allow_trace - Allow CPU tracing in the respective ELs,
++ * as configured by the drvdata->config.mode for the current
++ * session. Even though we have TRCVICTLR bits to filter the
++ * trace in the ELs, it doesn't prevent the ETM from generating
++ * a packet (e.g, TraceInfo) that might contain the addresses from
++ * the excluded levels. Thus we use the additional controls provided
++ * via the Trace Filtering controls (FEAT_TRF) to make sure no trace
++ * is generated for the excluded ELs.
++ */
++static void etm4x_allow_trace(struct etmv4_drvdata *drvdata)
++{
++	u64 trfcr = drvdata->trfcr;
++
++	/* If the CPU doesn't support FEAT_TRF, nothing to do */
++	if (!trfcr)
++		return;
++
++	if (drvdata->config.mode & ETM_MODE_EXCL_KERN)
++		trfcr &= ~TRFCR_ELx_ExTRE;
++	if (drvdata->config.mode & ETM_MODE_EXCL_USER)
++		trfcr &= ~TRFCR_ELx_E0TRE;
++
++	write_trfcr(trfcr);
++}
++
+ #ifdef CONFIG_ETM4X_IMPDEF_FEATURE
+ 
+ #define HISI_HIP08_AMBA_ID		0x000b6d01
+@@ -441,6 +480,7 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
+ 	if (etm4x_is_ete(drvdata))
+ 		etm4x_relaxed_write32(csa, TRCRSR_TA, TRCRSR);
+ 
++	etm4x_allow_trace(drvdata);
+ 	/* Enable the trace unit */
+ 	etm4x_relaxed_write32(csa, 1, TRCPRGCTLR);
+ 
+@@ -724,7 +764,6 @@ static int etm4_enable(struct coresight_device *csdev,
+ static void etm4_disable_hw(void *info)
+ {
+ 	u32 control;
+-	u64 trfcr;
+ 	struct etmv4_drvdata *drvdata = info;
+ 	struct etmv4_config *config = &drvdata->config;
+ 	struct coresight_device *csdev = drvdata->csdev;
+@@ -751,12 +790,7 @@ static void etm4_disable_hw(void *info)
+ 	 * If the CPU supports v8.4 Trace filter Control,
+ 	 * set the ETM to trace prohibited region.
+ 	 */
+-	if (drvdata->trfc) {
+-		trfcr = read_sysreg_s(SYS_TRFCR_EL1);
+-		write_sysreg_s(trfcr & ~(TRFCR_ELx_ExTRE | TRFCR_ELx_E0TRE),
+-			       SYS_TRFCR_EL1);
+-		isb();
+-	}
++	etm4x_prohibit_trace(drvdata);
+ 	/*
+ 	 * Make sure everything completes before disabling, as recommended
+ 	 * by section 7.3.77 ("TRCVICTLR, ViewInst Main Control Register,
+@@ -772,9 +806,6 @@ static void etm4_disable_hw(void *info)
+ 	if (coresight_timeout(csa, TRCSTATR, TRCSTATR_PMSTABLE_BIT, 1))
+ 		dev_err(etm_dev,
+ 			"timeout while waiting for PM stable Trace Status\n");
+-	if (drvdata->trfc)
+-		write_sysreg_s(trfcr, SYS_TRFCR_EL1);
+-
+ 	/* read the status of the single shot comparators */
+ 	for (i = 0; i < drvdata->nr_ss_cmp; i++) {
+ 		config->ss_status[i] =
+@@ -969,15 +1000,15 @@ static bool etm4_init_csdev_access(struct etmv4_drvdata *drvdata,
+ 	return false;
+ }
+ 
+-static void cpu_enable_tracing(struct etmv4_drvdata *drvdata)
++static void cpu_detect_trace_filtering(struct etmv4_drvdata *drvdata)
+ {
+ 	u64 dfr0 = read_sysreg(id_aa64dfr0_el1);
+ 	u64 trfcr;
+ 
++	drvdata->trfcr = 0;
+ 	if (!cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_TRACE_FILT_SHIFT))
+ 		return;
+ 
+-	drvdata->trfc = true;
+ 	/*
+ 	 * If the CPU supports v8.4 SelfHosted Tracing, enable
+ 	 * tracing at the kernel EL and EL0, forcing to use the
+@@ -991,7 +1022,7 @@ static void cpu_enable_tracing(struct etmv4_drvdata *drvdata)
+ 	if (is_kernel_in_hyp_mode())
+ 		trfcr |= TRFCR_EL2_CX;
+ 
+-	write_trfcr(trfcr);
++	drvdata->trfcr = trfcr;
+ }
+ 
+ static void etm4_init_arch_data(void *info)
+@@ -1177,7 +1208,7 @@ 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(drvdata);
++	cpu_detect_trace_filtering(drvdata);
+ }
+ 
+ static inline u32 etm4_get_victlr_access_type(struct etmv4_config *config)
+@@ -1673,7 +1704,7 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
+ 	int ret = 0;
+ 
+ 	/* Save the TRFCR irrespective of whether the ETM is ON */
+-	if (drvdata->trfc)
++	if (drvdata->trfcr)
+ 		drvdata->save_trfcr = read_trfcr();
+ 	/*
+ 	 * Save and restore the ETM Trace registers only if
+@@ -1782,7 +1813,7 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
+ 
+ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
+ {
+-	if (drvdata->trfc)
++	if (drvdata->trfcr)
+ 		write_trfcr(drvdata->save_trfcr);
+ 	if (drvdata->state_needs_restore)
+ 		__etm4_cpu_restore(drvdata);
+diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
+index 82cba16b73a6..3c4d69b096ca 100644
+--- a/drivers/hwtracing/coresight/coresight-etm4x.h
++++ b/drivers/hwtracing/coresight/coresight-etm4x.h
+@@ -919,7 +919,10 @@ struct etmv4_save_state {
+  * @nooverflow:	Indicate if overflow prevention is supported.
+  * @atbtrig:	If the implementation can support ATB triggers
+  * @lpoverride:	If the implementation can support low-power state over.
+- * @trfc:	If the implementation supports Arm v8.4 trace filter controls.
++ * @trfcr:	If the CPU supports FEAT_TRF, value of the TRFCR_ELx that
++ *		allows tracing at all ELs. We don't want to compute this
++ *		at runtime, due to the additional setting of TRFCR_CX when
++ *		in EL2. Otherwise, 0.
+  * @config:	structure holding configuration parameters.
+  * @save_trfcr:	Saved TRFCR_EL1 register during a CPU PM event.
+  * @save_state:	State to be preserved across power loss
+@@ -972,7 +975,7 @@ struct etmv4_drvdata {
+ 	bool				nooverflow;
+ 	bool				atbtrig;
+ 	bool				lpoverride;
+-	bool				trfc;
++	u64				trfcr;
+ 	struct etmv4_config		config;
+ 	u64				save_trfcr;
+ 	struct etmv4_save_state		*save_state;
+diff --git a/drivers/hwtracing/coresight/coresight-self-hosted-trace.h b/drivers/hwtracing/coresight/coresight-self-hosted-trace.h
+index 303d71911870..23f05df3f173 100644
+--- a/drivers/hwtracing/coresight/coresight-self-hosted-trace.h
++++ b/drivers/hwtracing/coresight/coresight-self-hosted-trace.h
+@@ -21,4 +21,11 @@ static inline void write_trfcr(u64 val)
+ 	isb();
+ }
+ 
++static inline void cpu_prohibit_trace(void)
++{
++	u64 trfcr = read_trfcr();
++
++	/* Prohibit tracing at EL0 & the kernel EL */
++	write_trfcr(trfcr & ~(TRFCR_ELx_ExTRE | TRFCR_ELx_E0TRE));
++}
+ #endif /*  __CORESIGHT_SELF_HOSTED_TRACE_H */
+-- 
+2.34.1
+