lib/extensions/amu/aarch64/amu.c - filogic/atf - Gitiles

 /*
  * Copyright (c) 2017-2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */

 #include <assert.h>
 #include <stdbool.h>

 #include <arch.h>
 #include <arch_features.h>
 #include <arch_helpers.h>

 #include <lib/el3_runtime/pubsub_events.h>
 #include <lib/extensions/amu.h>
 #include <lib/extensions/amu_private.h>

 #include <plat/common/platform.h>

 static struct amu_ctx amu_ctxs[PLATFORM_CORE_COUNT];

 /*
  * Get AMU version value from aa64pfr0.
  * Return values
  *   ID_AA64PFR0_AMU_V1: FEAT_AMUv1 supported (introduced in ARM v8.4)
  *   ID_AA64PFR0_AMU_V1P1: FEAT_AMUv1p1 supported (introduced in ARM v8.6)
  *   ID_AA64PFR0_AMU_NOT_SUPPORTED: not supported
  */
 unsigned int amu_get_version(void)
 {
 	return (unsigned int)(read_id_aa64pfr0_el1() >> ID_AA64PFR0_AMU_SHIFT) &
 		ID_AA64PFR0_AMU_MASK;
 }

 #if AMU_GROUP1_NR_COUNTERS
 /* Check if group 1 counters is implemented */
 bool amu_group1_supported(void)
 {
 	uint64_t features = read_amcfgr_el0() >> AMCFGR_EL0_NCG_SHIFT;

 	return (features & AMCFGR_EL0_NCG_MASK) == 1U;
 }
 #endif

 /*
  * Enable counters. This function is meant to be invoked
  * by the context management library before exiting from EL3.
  */
 void amu_enable(bool el2_unused)
 {
 	uint64_t v;
 	unsigned int amu_version = amu_get_version();

 	if (amu_version == ID_AA64PFR0_AMU_NOT_SUPPORTED) {
 		return;
 	}

 #if AMU_GROUP1_NR_COUNTERS
 	/* Check and set presence of group 1 counters */
 	if (!amu_group1_supported()) {
 		ERROR("AMU Counter Group 1 is not implemented\n");
 		panic();
 	}

 	/* Check number of group 1 counters */
 	uint64_t cnt_num = (read_amcgcr_el0() >> AMCGCR_EL0_CG1NC_SHIFT) &
 				AMCGCR_EL0_CG1NC_MASK;
 	VERBOSE("%s%llu. %s%u\n",
 		"Number of AMU Group 1 Counters ", cnt_num,
 		"Requested number ", AMU_GROUP1_NR_COUNTERS);

 	if (cnt_num < AMU_GROUP1_NR_COUNTERS) {
 		ERROR("%s%llu is less than %s%u\n",
 		"Number of AMU Group 1 Counters ", cnt_num,
 		"Requested number ", AMU_GROUP1_NR_COUNTERS);
 		panic();
 	}
 #endif

 	if (el2_unused) {
 		/*
 		 * CPTR_EL2.TAM: Set to zero so any accesses to
 		 * the Activity Monitor registers do not trap to EL2.
 		 */
 		v = read_cptr_el2();
 		v &= ~CPTR_EL2_TAM_BIT;
 		write_cptr_el2(v);
 	}

 	/*
 	 * CPTR_EL3.TAM: Set to zero so that any accesses to
 	 * the Activity Monitor registers do not trap to EL3.
 	 */
 	v = read_cptr_el3();
 	v &= ~TAM_BIT;
 	write_cptr_el3(v);

 	/* Enable group 0 counters */
 	write_amcntenset0_el0(AMU_GROUP0_COUNTERS_MASK);

 #if AMU_GROUP1_NR_COUNTERS
 	/* Enable group 1 counters */
 	write_amcntenset1_el0(AMU_GROUP1_COUNTERS_MASK);
 #endif

 	/* Initialize FEAT_AMUv1p1 features if present. */
 	if (amu_version < ID_AA64PFR0_AMU_V1P1) {
 		return;
 	}

 	if (el2_unused) {
 		/* Make sure virtual offsets are disabled if EL2 not used. */
 		write_hcr_el2(read_hcr_el2() & ~HCR_AMVOFFEN_BIT);
 	}

 #if AMU_RESTRICT_COUNTERS
 	/*
 	 * FEAT_AMUv1p1 adds a register field to restrict access to group 1
 	 * counters at all but the highest implemented EL.  This is controlled
 	 * with the AMU_RESTRICT_COUNTERS compile time flag, when set, system
 	 * register reads at lower ELs return zero.  Reads from the memory
 	 * mapped view are unaffected.
 	 */
 	VERBOSE("AMU group 1 counter access restricted.\n");
 	write_amcr_el0(read_amcr_el0() | AMCR_CG1RZ_BIT);
 #else
 	write_amcr_el0(read_amcr_el0() & ~AMCR_CG1RZ_BIT);
 #endif
 }

 /* Read the group 0 counter identified by the given `idx`. */
 uint64_t amu_group0_cnt_read(unsigned int idx)
 {
 	assert(amu_get_version() != ID_AA64PFR0_AMU_NOT_SUPPORTED);
 	assert(idx < AMU_GROUP0_NR_COUNTERS);

 	return amu_group0_cnt_read_internal(idx);
 }

 /* Write the group 0 counter identified by the given `idx` with `val` */
 void amu_group0_cnt_write(unsigned  int idx, uint64_t val)
 {
 	assert(amu_get_version() != ID_AA64PFR0_AMU_NOT_SUPPORTED);
 	assert(idx < AMU_GROUP0_NR_COUNTERS);

 	amu_group0_cnt_write_internal(idx, val);
 	isb();
 }

 /*
  * Read the group 0 offset register for a given index. Index must be 0, 2,
  * or 3, the register for 1 does not exist.
  *
  * Using this function requires FEAT_AMUv1p1 support.
  */
 uint64_t amu_group0_voffset_read(unsigned int idx)
 {
 	assert(amu_get_version() >= ID_AA64PFR0_AMU_V1P1);
 	assert(idx < AMU_GROUP0_NR_COUNTERS);
 	assert(idx != 1U);

 	return amu_group0_voffset_read_internal(idx);
 }

 /*
  * Write the group 0 offset register for a given index. Index must be 0, 2, or
  * 3, the register for 1 does not exist.
  *
  * Using this function requires FEAT_AMUv1p1 support.
  */
 void amu_group0_voffset_write(unsigned int idx, uint64_t val)
 {
 	assert(amu_get_version() >= ID_AA64PFR0_AMU_V1P1);
 	assert(idx < AMU_GROUP0_NR_COUNTERS);
 	assert(idx != 1U);

 	amu_group0_voffset_write_internal(idx, val);
 	isb();
 }

 #if AMU_GROUP1_NR_COUNTERS
 /* Read the group 1 counter identified by the given `idx` */
 uint64_t amu_group1_cnt_read(unsigned int idx)
 {
 	assert(amu_get_version() != ID_AA64PFR0_AMU_NOT_SUPPORTED);
 	assert(amu_group1_supported());
 	assert(idx < AMU_GROUP1_NR_COUNTERS);

 	return amu_group1_cnt_read_internal(idx);
 }

 /* Write the group 1 counter identified by the given `idx` with `val` */
 void amu_group1_cnt_write(unsigned int idx, uint64_t val)
 {
 	assert(amu_get_version() != ID_AA64PFR0_AMU_NOT_SUPPORTED);
 	assert(amu_group1_supported());
 	assert(idx < AMU_GROUP1_NR_COUNTERS);

 	amu_group1_cnt_write_internal(idx, val);
 	isb();
 }

 /*
  * Read the group 1 offset register for a given index.
  *
  * Using this function requires FEAT_AMUv1p1 support.
  */
 uint64_t amu_group1_voffset_read(unsigned int idx)
 {
 	assert(amu_get_version() >= ID_AA64PFR0_AMU_V1P1);
 	assert(amu_group1_supported());
 	assert(idx < AMU_GROUP1_NR_COUNTERS);
 	assert(((read_amcg1idr_el0() >> AMCG1IDR_VOFF_SHIFT) &
 		(1ULL << idx)) != 0ULL);

 	return amu_group1_voffset_read_internal(idx);
 }

 /*
  * Write the group 1 offset register for a given index.
  *
  * Using this function requires FEAT_AMUv1p1 support.
  */
 void amu_group1_voffset_write(unsigned int idx, uint64_t val)
 {
 	assert(amu_get_version() >= ID_AA64PFR0_AMU_V1P1);
 	assert(amu_group1_supported());
 	assert(idx < AMU_GROUP1_NR_COUNTERS);
 	assert(((read_amcg1idr_el0() >> AMCG1IDR_VOFF_SHIFT) &
 		(1ULL << idx)) != 0ULL);

 	amu_group1_voffset_write_internal(idx, val);
 	isb();
 }

 /*
  * Program the event type register for the given `idx` with
  * the event number `val`
  */
 void amu_group1_set_evtype(unsigned int idx, unsigned int val)
 {
 	assert(amu_get_version() != ID_AA64PFR0_AMU_NOT_SUPPORTED);
 	assert(amu_group1_supported());
 	assert(idx < AMU_GROUP1_NR_COUNTERS);

 	amu_group1_set_evtype_internal(idx, val);
 	isb();
 }
 #endif	/* AMU_GROUP1_NR_COUNTERS */

 static void *amu_context_save(const void *arg)
 {
 	struct amu_ctx *ctx = &amu_ctxs[plat_my_core_pos()];
 	unsigned int i;

 	if (amu_get_version() == ID_AA64PFR0_AMU_NOT_SUPPORTED) {
 		return (void *)-1;
 	}

 #if AMU_GROUP1_NR_COUNTERS
 	if (!amu_group1_supported()) {
 		return (void *)-1;
 	}
 #endif
 	/* Assert that group 0/1 counter configuration is what we expect */
 	assert(read_amcntenset0_el0() == AMU_GROUP0_COUNTERS_MASK);

 #if AMU_GROUP1_NR_COUNTERS
 	assert(read_amcntenset1_el0() == AMU_GROUP1_COUNTERS_MASK);
 #endif
 	/*
 	 * Disable group 0/1 counters to avoid other observers like SCP sampling
 	 * counter values from the future via the memory mapped view.
 	 */
 	write_amcntenclr0_el0(AMU_GROUP0_COUNTERS_MASK);

 #if AMU_GROUP1_NR_COUNTERS
 	write_amcntenclr1_el0(AMU_GROUP1_COUNTERS_MASK);
 #endif
 	isb();

 	/* Save all group 0 counters */
 	for (i = 0U; i < AMU_GROUP0_NR_COUNTERS; i++) {
 		ctx->group0_cnts[i] = amu_group0_cnt_read(i);
 	}

 	/* Save group 0 virtual offsets if supported and enabled. */
 	if ((amu_get_version() >= ID_AA64PFR0_AMU_V1P1) &&
 			((read_hcr_el2() & HCR_AMVOFFEN_BIT) != 0ULL)) {
 		/* Not using a loop because count is fixed and index 1 DNE. */
 		ctx->group0_voffsets[0U] = amu_group0_voffset_read(0U);
 		ctx->group0_voffsets[1U] = amu_group0_voffset_read(2U);
 		ctx->group0_voffsets[2U] = amu_group0_voffset_read(3U);
 	}

 #if AMU_GROUP1_NR_COUNTERS
 	/* Save group 1 counters */
 	for (i = 0U; i < AMU_GROUP1_NR_COUNTERS; i++) {
 		if ((AMU_GROUP1_COUNTERS_MASK & (1UL << i)) != 0U) {
 			ctx->group1_cnts[i] = amu_group1_cnt_read(i);
 		}
 	}

 	/* Save group 1 virtual offsets if supported and enabled. */
 	if ((amu_get_version() >= ID_AA64PFR0_AMU_V1P1) &&
 			((read_hcr_el2() & HCR_AMVOFFEN_BIT) != 0ULL)) {
 		u_register_t amcg1idr = read_amcg1idr_el0() >>
 			AMCG1IDR_VOFF_SHIFT;
 		amcg1idr = amcg1idr & AMU_GROUP1_COUNTERS_MASK;

 		for (i = 0U; i < AMU_GROUP1_NR_COUNTERS; i++) {
 			if (((amcg1idr >> i) & 1ULL) != 0ULL) {
 				ctx->group1_voffsets[i] =
 					amu_group1_voffset_read(i);
 			}
 		}
 	}
 #endif
 	return (void *)0;
 }

 static void *amu_context_restore(const void *arg)
 {
 	struct amu_ctx *ctx = &amu_ctxs[plat_my_core_pos()];
 	unsigned int i;

 	if (amu_get_version() == ID_AA64PFR0_AMU_NOT_SUPPORTED) {
 		return (void *)-1;
 	}

 #if AMU_GROUP1_NR_COUNTERS
 	if (!amu_group1_supported()) {
 		return (void *)-1;
 	}
 #endif
 	/* Counters were disabled in `amu_context_save()` */
 	assert(read_amcntenset0_el0() == 0U);

 #if AMU_GROUP1_NR_COUNTERS
 	assert(read_amcntenset1_el0() == 0U);
 #endif

 	/* Restore all group 0 counters */
 	for (i = 0U; i < AMU_GROUP0_NR_COUNTERS; i++) {
 		amu_group0_cnt_write(i, ctx->group0_cnts[i]);
 	}

 	/* Restore group 0 virtual offsets if supported and enabled. */
 	if ((amu_get_version() >= ID_AA64PFR0_AMU_V1P1) &&
 			((read_hcr_el2() & HCR_AMVOFFEN_BIT) != 0ULL)) {
 		/* Not using a loop because count is fixed and index 1 DNE. */
 		amu_group0_voffset_write(0U, ctx->group0_voffsets[0U]);
 		amu_group0_voffset_write(2U, ctx->group0_voffsets[1U]);
 		amu_group0_voffset_write(3U, ctx->group0_voffsets[2U]);
 	}

 	/* Restore group 0 counter configuration */
 	write_amcntenset0_el0(AMU_GROUP0_COUNTERS_MASK);

 #if AMU_GROUP1_NR_COUNTERS
 	/* Restore group 1 counters */
 	for (i = 0U; i < AMU_GROUP1_NR_COUNTERS; i++) {
 		if ((AMU_GROUP1_COUNTERS_MASK & (1UL << i)) != 0U) {
 			amu_group1_cnt_write(i, ctx->group1_cnts[i]);
 		}
 	}

 	/* Restore group 1 virtual offsets if supported and enabled. */
 	if ((amu_get_version() >= ID_AA64PFR0_AMU_V1P1) &&
 			((read_hcr_el2() & HCR_AMVOFFEN_BIT) != 0ULL)) {
 		u_register_t amcg1idr = read_amcg1idr_el0() >>
 			AMCG1IDR_VOFF_SHIFT;
 		amcg1idr = amcg1idr & AMU_GROUP1_COUNTERS_MASK;

 		for (i = 0U; i < AMU_GROUP1_NR_COUNTERS; i++) {
 			if (((amcg1idr >> i) & 1ULL) != 0ULL) {
 				amu_group1_voffset_write(i,
 					ctx->group1_voffsets[i]);
 			}
 		}
 	}

 	/* Restore group 1 counter configuration */
 	write_amcntenset1_el0(AMU_GROUP1_COUNTERS_MASK);
 #endif

 	return (void *)0;
 }

 SUBSCRIBE_TO_EVENT(psci_suspend_pwrdown_start, amu_context_save);
 SUBSCRIBE_TO_EVENT(psci_suspend_pwrdown_finish, amu_context_restore);
	/*
	* Copyright (c) 2017-2021, ARM Limited and Contributors. All rights reserved.
	*
	* SPDX-License-Identifier: BSD-3-Clause
	*/

	#include <assert.h>
	#include <stdbool.h>

	#include <arch.h>
	#include <arch_features.h>
	#include <arch_helpers.h>

	#include <lib/el3_runtime/pubsub_events.h>
	#include <lib/extensions/amu.h>
	#include <lib/extensions/amu_private.h>

	#include <plat/common/platform.h>

	static struct amu_ctx amu_ctxs[PLATFORM_CORE_COUNT];

	/*
	* Get AMU version value from aa64pfr0.
	* Return values
	* ID_AA64PFR0_AMU_V1: FEAT_AMUv1 supported (introduced in ARM v8.4)
	* ID_AA64PFR0_AMU_V1P1: FEAT_AMUv1p1 supported (introduced in ARM v8.6)
	* ID_AA64PFR0_AMU_NOT_SUPPORTED: not supported
	*/
	unsigned int amu_get_version(void)
	{
	return (unsigned int)(read_id_aa64pfr0_el1() >> ID_AA64PFR0_AMU_SHIFT) &
	ID_AA64PFR0_AMU_MASK;
	}

	#if AMU_GROUP1_NR_COUNTERS
	/* Check if group 1 counters is implemented */
	bool amu_group1_supported(void)
	{
	uint64_t features = read_amcfgr_el0() >> AMCFGR_EL0_NCG_SHIFT;

	return (features & AMCFGR_EL0_NCG_MASK) == 1U;
	}
	#endif

	/*
	* Enable counters. This function is meant to be invoked
	* by the context management library before exiting from EL3.
	*/
	void amu_enable(bool el2_unused)
	{
	uint64_t v;
	unsigned int amu_version = amu_get_version();

	if (amu_version == ID_AA64PFR0_AMU_NOT_SUPPORTED) {
	return;
	}

	#if AMU_GROUP1_NR_COUNTERS
	/* Check and set presence of group 1 counters */
	if (!amu_group1_supported()) {
	ERROR("AMU Counter Group 1 is not implemented\n");
	panic();
	}

	/* Check number of group 1 counters */
	uint64_t cnt_num = (read_amcgcr_el0() >> AMCGCR_EL0_CG1NC_SHIFT) &
	AMCGCR_EL0_CG1NC_MASK;
	VERBOSE("%s%llu. %s%u\n",
	"Number of AMU Group 1 Counters ", cnt_num,
	"Requested number ", AMU_GROUP1_NR_COUNTERS);

	if (cnt_num < AMU_GROUP1_NR_COUNTERS) {
	ERROR("%s%llu is less than %s%u\n",
	"Number of AMU Group 1 Counters ", cnt_num,
	"Requested number ", AMU_GROUP1_NR_COUNTERS);
	panic();
	}
	#endif

	if (el2_unused) {
	/*
	* CPTR_EL2.TAM: Set to zero so any accesses to
	* the Activity Monitor registers do not trap to EL2.
	*/
	v = read_cptr_el2();
	v &= ~CPTR_EL2_TAM_BIT;
	write_cptr_el2(v);
	}

	/*
	* CPTR_EL3.TAM: Set to zero so that any accesses to
	* the Activity Monitor registers do not trap to EL3.
	*/
	v = read_cptr_el3();
	v &= ~TAM_BIT;
	write_cptr_el3(v);

	/* Enable group 0 counters */
	write_amcntenset0_el0(AMU_GROUP0_COUNTERS_MASK);

	#if AMU_GROUP1_NR_COUNTERS
	/* Enable group 1 counters */
	write_amcntenset1_el0(AMU_GROUP1_COUNTERS_MASK);
	#endif

	/* Initialize FEAT_AMUv1p1 features if present. */
	if (amu_version < ID_AA64PFR0_AMU_V1P1) {
	return;
	}

	if (el2_unused) {
	/* Make sure virtual offsets are disabled if EL2 not used. */
	write_hcr_el2(read_hcr_el2() & ~HCR_AMVOFFEN_BIT);
	}

	#if AMU_RESTRICT_COUNTERS
	/*
	* FEAT_AMUv1p1 adds a register field to restrict access to group 1
	* counters at all but the highest implemented EL. This is controlled
	* with the AMU_RESTRICT_COUNTERS compile time flag, when set, system
	* register reads at lower ELs return zero. Reads from the memory
	* mapped view are unaffected.
	*/
	VERBOSE("AMU group 1 counter access restricted.\n");
	write_amcr_el0(read_amcr_el0() \| AMCR_CG1RZ_BIT);
	#else
	write_amcr_el0(read_amcr_el0() & ~AMCR_CG1RZ_BIT);
	#endif
	}

	/* Read the group 0 counter identified by the given `idx`. */
	uint64_t amu_group0_cnt_read(unsigned int idx)
	{
	assert(amu_get_version() != ID_AA64PFR0_AMU_NOT_SUPPORTED);
	assert(idx < AMU_GROUP0_NR_COUNTERS);

	return amu_group0_cnt_read_internal(idx);
	}

	/* Write the group 0 counter identified by the given `idx` with `val` */
	void amu_group0_cnt_write(unsigned int idx, uint64_t val)
	{
	assert(amu_get_version() != ID_AA64PFR0_AMU_NOT_SUPPORTED);
	assert(idx < AMU_GROUP0_NR_COUNTERS);

	amu_group0_cnt_write_internal(idx, val);
	isb();
	}

	/*
	* Read the group 0 offset register for a given index. Index must be 0, 2,
	* or 3, the register for 1 does not exist.
	*
	* Using this function requires FEAT_AMUv1p1 support.
	*/
	uint64_t amu_group0_voffset_read(unsigned int idx)
	{
	assert(amu_get_version() >= ID_AA64PFR0_AMU_V1P1);
	assert(idx < AMU_GROUP0_NR_COUNTERS);
	assert(idx != 1U);

	return amu_group0_voffset_read_internal(idx);
	}

	/*
	* Write the group 0 offset register for a given index. Index must be 0, 2, or
	* 3, the register for 1 does not exist.
	*
	* Using this function requires FEAT_AMUv1p1 support.
	*/
	void amu_group0_voffset_write(unsigned int idx, uint64_t val)
	{
	assert(amu_get_version() >= ID_AA64PFR0_AMU_V1P1);
	assert(idx < AMU_GROUP0_NR_COUNTERS);
	assert(idx != 1U);

	amu_group0_voffset_write_internal(idx, val);
	isb();
	}

	#if AMU_GROUP1_NR_COUNTERS
	/* Read the group 1 counter identified by the given `idx` */
	uint64_t amu_group1_cnt_read(unsigned int idx)
	{
	assert(amu_get_version() != ID_AA64PFR0_AMU_NOT_SUPPORTED);
	assert(amu_group1_supported());
	assert(idx < AMU_GROUP1_NR_COUNTERS);

	return amu_group1_cnt_read_internal(idx);
	}

	/* Write the group 1 counter identified by the given `idx` with `val` */
	void amu_group1_cnt_write(unsigned int idx, uint64_t val)
	{
	assert(amu_get_version() != ID_AA64PFR0_AMU_NOT_SUPPORTED);
	assert(amu_group1_supported());
	assert(idx < AMU_GROUP1_NR_COUNTERS);

	amu_group1_cnt_write_internal(idx, val);
	isb();
	}

	/*
	* Read the group 1 offset register for a given index.
	*
	* Using this function requires FEAT_AMUv1p1 support.
	*/
	uint64_t amu_group1_voffset_read(unsigned int idx)
	{
	assert(amu_get_version() >= ID_AA64PFR0_AMU_V1P1);
	assert(amu_group1_supported());
	assert(idx < AMU_GROUP1_NR_COUNTERS);
	assert(((read_amcg1idr_el0() >> AMCG1IDR_VOFF_SHIFT) &
	(1ULL << idx)) != 0ULL);

	return amu_group1_voffset_read_internal(idx);
	}

	/*
	* Write the group 1 offset register for a given index.
	*
	* Using this function requires FEAT_AMUv1p1 support.
	*/
	void amu_group1_voffset_write(unsigned int idx, uint64_t val)
	{
	assert(amu_get_version() >= ID_AA64PFR0_AMU_V1P1);
	assert(amu_group1_supported());
	assert(idx < AMU_GROUP1_NR_COUNTERS);
	assert(((read_amcg1idr_el0() >> AMCG1IDR_VOFF_SHIFT) &
	(1ULL << idx)) != 0ULL);

	amu_group1_voffset_write_internal(idx, val);
	isb();
	}

	/*
	* Program the event type register for the given `idx` with
	* the event number `val`
	*/
	void amu_group1_set_evtype(unsigned int idx, unsigned int val)
	{
	assert(amu_get_version() != ID_AA64PFR0_AMU_NOT_SUPPORTED);
	assert(amu_group1_supported());
	assert(idx < AMU_GROUP1_NR_COUNTERS);

	amu_group1_set_evtype_internal(idx, val);
	isb();
	}
	#endif /* AMU_GROUP1_NR_COUNTERS */

	static void amu_context_save(const void arg)
	{
	struct amu_ctx *ctx = &amu_ctxs[plat_my_core_pos()];
	unsigned int i;

	if (amu_get_version() == ID_AA64PFR0_AMU_NOT_SUPPORTED) {
	return (void *)-1;
	}

	#if AMU_GROUP1_NR_COUNTERS
	if (!amu_group1_supported()) {
	return (void *)-1;
	}
	#endif
	/* Assert that group 0/1 counter configuration is what we expect */
	assert(read_amcntenset0_el0() == AMU_GROUP0_COUNTERS_MASK);

	#if AMU_GROUP1_NR_COUNTERS
	assert(read_amcntenset1_el0() == AMU_GROUP1_COUNTERS_MASK);
	#endif
	/*
	* Disable group 0/1 counters to avoid other observers like SCP sampling
	* counter values from the future via the memory mapped view.
	*/
	write_amcntenclr0_el0(AMU_GROUP0_COUNTERS_MASK);

	#if AMU_GROUP1_NR_COUNTERS
	write_amcntenclr1_el0(AMU_GROUP1_COUNTERS_MASK);
	#endif
	isb();

	/* Save all group 0 counters */
	for (i = 0U; i < AMU_GROUP0_NR_COUNTERS; i++) {
	ctx->group0_cnts[i] = amu_group0_cnt_read(i);
	}

	/* Save group 0 virtual offsets if supported and enabled. */
	if ((amu_get_version() >= ID_AA64PFR0_AMU_V1P1) &&
	((read_hcr_el2() & HCR_AMVOFFEN_BIT) != 0ULL)) {
	/* Not using a loop because count is fixed and index 1 DNE. */
	ctx->group0_voffsets[0U] = amu_group0_voffset_read(0U);
	ctx->group0_voffsets[1U] = amu_group0_voffset_read(2U);
	ctx->group0_voffsets[2U] = amu_group0_voffset_read(3U);
	}

	#if AMU_GROUP1_NR_COUNTERS
	/* Save group 1 counters */
	for (i = 0U; i < AMU_GROUP1_NR_COUNTERS; i++) {
	if ((AMU_GROUP1_COUNTERS_MASK & (1UL << i)) != 0U) {
	ctx->group1_cnts[i] = amu_group1_cnt_read(i);
	}
	}

	/* Save group 1 virtual offsets if supported and enabled. */
	if ((amu_get_version() >= ID_AA64PFR0_AMU_V1P1) &&
	((read_hcr_el2() & HCR_AMVOFFEN_BIT) != 0ULL)) {
	u_register_t amcg1idr = read_amcg1idr_el0() >>
	AMCG1IDR_VOFF_SHIFT;
	amcg1idr = amcg1idr & AMU_GROUP1_COUNTERS_MASK;

	for (i = 0U; i < AMU_GROUP1_NR_COUNTERS; i++) {
	if (((amcg1idr >> i) & 1ULL) != 0ULL) {
	ctx->group1_voffsets[i] =
	amu_group1_voffset_read(i);
	}
	}
	}
	#endif
	return (void *)0;
	}

	static void amu_context_restore(const void arg)
	{
	struct amu_ctx *ctx = &amu_ctxs[plat_my_core_pos()];
	unsigned int i;

	if (amu_get_version() == ID_AA64PFR0_AMU_NOT_SUPPORTED) {
	return (void *)-1;
	}

	#if AMU_GROUP1_NR_COUNTERS
	if (!amu_group1_supported()) {
	return (void *)-1;
	}
	#endif
	/* Counters were disabled in `amu_context_save()` */
	assert(read_amcntenset0_el0() == 0U);

	#if AMU_GROUP1_NR_COUNTERS
	assert(read_amcntenset1_el0() == 0U);
	#endif

	/* Restore all group 0 counters */
	for (i = 0U; i < AMU_GROUP0_NR_COUNTERS; i++) {
	amu_group0_cnt_write(i, ctx->group0_cnts[i]);
	}

	/* Restore group 0 virtual offsets if supported and enabled. */
	if ((amu_get_version() >= ID_AA64PFR0_AMU_V1P1) &&
	((read_hcr_el2() & HCR_AMVOFFEN_BIT) != 0ULL)) {
	/* Not using a loop because count is fixed and index 1 DNE. */
	amu_group0_voffset_write(0U, ctx->group0_voffsets[0U]);
	amu_group0_voffset_write(2U, ctx->group0_voffsets[1U]);
	amu_group0_voffset_write(3U, ctx->group0_voffsets[2U]);
	}

	/* Restore group 0 counter configuration */
	write_amcntenset0_el0(AMU_GROUP0_COUNTERS_MASK);

	#if AMU_GROUP1_NR_COUNTERS
	/* Restore group 1 counters */
	for (i = 0U; i < AMU_GROUP1_NR_COUNTERS; i++) {
	if ((AMU_GROUP1_COUNTERS_MASK & (1UL << i)) != 0U) {
	amu_group1_cnt_write(i, ctx->group1_cnts[i]);
	}
	}

	/* Restore group 1 virtual offsets if supported and enabled. */
	if ((amu_get_version() >= ID_AA64PFR0_AMU_V1P1) &&
	((read_hcr_el2() & HCR_AMVOFFEN_BIT) != 0ULL)) {
	u_register_t amcg1idr = read_amcg1idr_el0() >>
	AMCG1IDR_VOFF_SHIFT;
	amcg1idr = amcg1idr & AMU_GROUP1_COUNTERS_MASK;

	for (i = 0U; i < AMU_GROUP1_NR_COUNTERS; i++) {
	if (((amcg1idr >> i) & 1ULL) != 0ULL) {
	amu_group1_voffset_write(i,
	ctx->group1_voffsets[i]);
	}
	}
	}

	/* Restore group 1 counter configuration */
	write_amcntenset1_el0(AMU_GROUP1_COUNTERS_MASK);
	#endif

	return (void *)0;
	}

	SUBSCRIBE_TO_EVENT(psci_suspend_pwrdown_start, amu_context_save);
	SUBSCRIBE_TO_EVENT(psci_suspend_pwrdown_finish, amu_context_restore);