[PATCH 0/3] Ampere Computing ETMv4.x Support

[PATCH 0/3] Ampere Computing ETMv4.x Support

[Steve Clevenger]

First pass at Ampere ETMv4.x support. Added Ampere ETM ID, and changes
required by the Ampere ETMv4.x hardware implementation.

Steve Clevenger (3):
  coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read
  coresight etm4x: Add 32-bit read/write option to split 64-bit words
  coresight etm4x: Add pr_debug statement for Coresight component
    PID/CID

 drivers/amba/bus.c                            |   7 ++
 .../coresight/coresight-etm4x-core.c          | 115 ++++++++++++++----
 drivers/hwtracing/coresight/coresight-etm4x.h |  34 ++++++
 3 files changed, 131 insertions(+), 25 deletions(-)

-- 
2.25.1


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[PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Steve Clevenger]

Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
Computing design decision MMIO reads are considered the same as an
external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
results in a bus fault followed by a kernel panic.  A TRCIDR1 read
is valid regardless of TRCOSLAR.OSLK provided MMIO access
(now deprecated) is supported.
AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation

Add Ampere ETM PID required for Coresight ETM driver support.

Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
---
 .../coresight/coresight-etm4x-core.c          | 36 +++++++++++++++----
 drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
 2 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 1cc052979e01..533be1928a09 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
 	drvdata = dev_get_drvdata(init_arg->dev);
 	csa = init_arg->csa;
 
+	/* Detect the support for OS Lock before we actually use it */
+	etm_detect_os_lock(drvdata, csa);
+
+	/*
+	 * For ETM implementations that consider MMIO an external access
+	 * clear TRCOSLAR.OSLK early.
+	 */
+	if (drvdata->mmio_external)
+		etm4_os_unlock_csa(drvdata, csa);
+
 	/*
 	 * If we are unable to detect the access mechanism,
 	 * or unable to detect the trace unit type, fail
-	 * early.
+	 * early. Reset TRCOSLAR.OSLK if cleared.
 	 */
-	if (!etm4_init_csdev_access(drvdata, csa))
+	if (!etm4_init_csdev_access(drvdata, csa)) {
+		if (drvdata->mmio_external)
+			etm4_os_lock(drvdata);
 		return;
+	}
 
-	/* Detect the support for OS Lock before we actually use it */
-	etm_detect_os_lock(drvdata, csa);
+	/*
+	 * Make sure all registers are accessible
+	 * TRCOSLAR.OSLK may already be clear
+	 */
+	if (!drvdata->mmio_external)
+		etm4_os_unlock_csa(drvdata, csa);
 
-	/* Make sure all registers are accessible */
-	etm4_os_unlock_csa(drvdata, csa);
 	etm4_cs_unlock(drvdata, csa);
 
 	etm4_check_arch_features(drvdata, init_arg->pid);
@@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
 	init_arg.csa = &access;
 	init_arg.pid = etm_pid;
 
+	/*
+	 * Ampere ETM v4.6 considers MMIO access as external. This mask
+	 * isolates the manufacturer JEP106 ID in the PID.
+	 * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
+	 */
+	if ((init_arg.pid & 0x000FF000) == 0x00096000)
+		drvdata->mmio_external = true;
+
 	/*
 	 * Serialize against CPUHP callbacks to avoid race condition
 	 * between the smp call and saving the delayed probe.
@@ -2192,6 +2215,7 @@ static const struct amba_id etm4_ids[] = {
 	CS_AMBA_ID(0x000bb95e),			/* Cortex-A57 */
 	CS_AMBA_ID(0x000bb95a),			/* Cortex-A72 */
 	CS_AMBA_ID(0x000bb959),			/* Cortex-A73 */
+	CS_AMBA_UCI_ID(0x00096000, uci_id_etm4),/* Ampere ARMv8 */
 	CS_AMBA_UCI_ID(0x000bb9da, uci_id_etm4),/* Cortex-A35 */
 	CS_AMBA_UCI_ID(0x000bbd05, uci_id_etm4),/* Cortex-A55 */
 	CS_AMBA_UCI_ID(0x000bbd0a, uci_id_etm4),/* Cortex-A75 */
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index 4b21bb79f168..cf4f9f2e1807 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -1015,6 +1015,7 @@ struct etmv4_save_state {
  * @skip_power_up: Indicates if an implementation can skip powering up
  *		   the trace unit.
  * @arch_features: Bitmap of arch features of etmv4 devices.
+ * @mmio_external: True if ETM considers MMIO an external access.
  */
 struct etmv4_drvdata {
 	void __iomem			*base;
@@ -1067,6 +1068,7 @@ struct etmv4_drvdata {
 	bool				state_needs_restore;
 	bool				skip_power_up;
 	DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
+	bool				mmio_external;
 };
 
 /* Address comparator access types */
-- 
2.25.1


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[PATCH 2/3] coresight etm4x: Add 32-bit read/write option to split 64-bit words

[Steve Clevenger]

Add 32-bit read/write access option for Ampere ETMv4.6 64-bit registers.
Ampere Computing erratum AC03_DEBUG_10 describes a design decision where
64-bit read/write access is not supported for the ETMv4.6 implementation.
These 64-bit registers must be accessed as 2 ea. 32-bit registers.
AC03_DEBUG_10 is described in the AmpereOne Developer Errata:
https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation

Fix drvdata->nr_addr_cmp for() loop range bug to drvdata->nr_addr_cmp * 2
in etm_enable_hw.

Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
---
 .../coresight/coresight-etm4x-core.c          | 81 ++++++++++++++-----
 drivers/hwtracing/coresight/coresight-etm4x.h | 32 ++++++++
 2 files changed, 93 insertions(+), 20 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 533be1928a09..bf4daa649cdf 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -452,18 +452,31 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
 		if (etm4x_sspcicrn_present(drvdata, i))
 			etm4x_relaxed_write32(csa, config->ss_pe_cmp[i], TRCSSPCICRn(i));
 	}
-	for (i = 0; i < drvdata->nr_addr_cmp; i++) {
-		etm4x_relaxed_write64(csa, config->addr_val[i], TRCACVRn(i));
-		etm4x_relaxed_write64(csa, config->addr_acc[i], TRCACATRn(i));
+	for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
+		if (drvdata->no_quad_mmio) {
+			etm4x_split_write64(csa, config->addr_val[i], TRCACVRn(i));
+			etm4x_split_write64(csa, config->addr_acc[i], TRCACATRn(i));
+		} else {
+			etm4x_relaxed_write64(csa, config->addr_val[i], TRCACVRn(i));
+			etm4x_relaxed_write64(csa, config->addr_acc[i], TRCACATRn(i));
+		}
+	}
+	for (i = 0; i < drvdata->numcidc; i++) {
+		if (drvdata->no_quad_mmio)
+			etm4x_split_write64(csa, config->ctxid_pid[i], TRCCIDCVRn(i));
+		else
+			etm4x_relaxed_write64(csa, config->ctxid_pid[i], TRCCIDCVRn(i));
 	}
-	for (i = 0; i < drvdata->numcidc; i++)
-		etm4x_relaxed_write64(csa, config->ctxid_pid[i], TRCCIDCVRn(i));
 	etm4x_relaxed_write32(csa, config->ctxid_mask0, TRCCIDCCTLR0);
 	if (drvdata->numcidc > 4)
 		etm4x_relaxed_write32(csa, config->ctxid_mask1, TRCCIDCCTLR1);
 
-	for (i = 0; i < drvdata->numvmidc; i++)
-		etm4x_relaxed_write64(csa, config->vmid_val[i], TRCVMIDCVRn(i));
+	for (i = 0; i < drvdata->numvmidc; i++) {
+		if (drvdata->no_quad_mmio)
+			etm4x_split_write64(csa, config->vmid_val[i], TRCVMIDCVRn(i));
+		else
+			etm4x_relaxed_write64(csa, config->vmid_val[i], TRCVMIDCVRn(i));
+	}
 	etm4x_relaxed_write32(csa, config->vmid_mask0, TRCVMIDCCTLR0);
 	if (drvdata->numvmidc > 4)
 		etm4x_relaxed_write32(csa, config->vmid_mask1, TRCVMIDCCTLR1);
@@ -1670,8 +1683,13 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
 	}
 
 	for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
-		state->trcacvr[i] = etm4x_read64(csa, TRCACVRn(i));
-		state->trcacatr[i] = etm4x_read64(csa, TRCACATRn(i));
+		if (drvdata->no_quad_mmio) {
+			state->trcacvr[i] = etm4x_split_read64(csa, TRCACVRn(i));
+			state->trcacatr[i] = etm4x_split_read64(csa, TRCACATRn(i));
+		} else {
+			state->trcacvr[i] = etm4x_read64(csa, TRCACVRn(i));
+			state->trcacatr[i] = etm4x_read64(csa, TRCACATRn(i));
+		}
 	}
 
 	/*
@@ -1681,11 +1699,19 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
 	 * unit") of ARM IHI 0064D.
 	 */
 
-	for (i = 0; i < drvdata->numcidc; i++)
-		state->trccidcvr[i] = etm4x_read64(csa, TRCCIDCVRn(i));
+	for (i = 0; i < drvdata->numcidc; i++) {
+		if (drvdata->no_quad_mmio) 
+			state->trccidcvr[i] = etm4x_split_read64(csa, TRCCIDCVRn(i));
+		else
+			state->trccidcvr[i] = etm4x_read64(csa, TRCCIDCVRn(i));
+	}
 
-	for (i = 0; i < drvdata->numvmidc; i++)
-		state->trcvmidcvr[i] = etm4x_read64(csa, TRCVMIDCVRn(i));
+	for (i = 0; i < drvdata->numvmidc; i++) {
+		if (drvdata->no_quad_mmio)
+			state->trcvmidcvr[i] = etm4x_split_read64(csa, TRCVMIDCVRn(i));
+		else
+			state->trcvmidcvr[i] = etm4x_read64(csa, TRCVMIDCVRn(i));
+	}
 
 	state->trccidcctlr0 = etm4x_read32(csa, TRCCIDCCTLR0);
 	if (drvdata->numcidc > 4)
@@ -1799,15 +1825,28 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
 	}
 
 	for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
-		etm4x_relaxed_write64(csa, state->trcacvr[i], TRCACVRn(i));
-		etm4x_relaxed_write64(csa, state->trcacatr[i], TRCACATRn(i));
+		if (drvdata->no_quad_mmio) {
+			etm4x_split_write64(csa, state->trcacvr[i], TRCACVRn(i));
+			etm4x_split_write64(csa, state->trcacatr[i], TRCACATRn(i));
+		} else {
+			etm4x_relaxed_write64(csa, state->trcacvr[i], TRCACVRn(i));
+			etm4x_relaxed_write64(csa, state->trcacatr[i], TRCACATRn(i));
+		}
 	}
 
-	for (i = 0; i < drvdata->numcidc; i++)
-		etm4x_relaxed_write64(csa, state->trccidcvr[i], TRCCIDCVRn(i));
+	for (i = 0; i < drvdata->numcidc; i++) {
+		if (drvdata->no_quad_mmio)
+			etm4x_split_write64(csa, state->trccidcvr[i], TRCCIDCVRn(i));
+		else
+			etm4x_relaxed_write64(csa, state->trccidcvr[i], TRCCIDCVRn(i));
+	}
 
-	for (i = 0; i < drvdata->numvmidc; i++)
-		etm4x_relaxed_write64(csa, state->trcvmidcvr[i], TRCVMIDCVRn(i));
+	for (i = 0; i < drvdata->numvmidc; i++) {
+		if (drvdata->no_quad_mmio)
+			etm4x_split_write64(csa, state->trcvmidcvr[i], TRCVMIDCVRn(i));
+		else
+			etm4x_relaxed_write64(csa, state->trcvmidcvr[i], TRCVMIDCVRn(i));
+	}
 
 	etm4x_relaxed_write32(csa, state->trccidcctlr0, TRCCIDCCTLR0);
 	if (drvdata->numcidc > 4)
@@ -2047,8 +2086,10 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
 	 * isolates the manufacturer JEP106 ID in the PID.
 	 * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
 	 */
-	if ((init_arg.pid & 0x000FF000) == 0x00096000)
+	if ((init_arg.pid & 0x000FF000) == 0x00096000) {
 		drvdata->mmio_external = true;
+		drvdata->no_quad_mmio = true;
+	}
 
 	/*
 	 * Serialize against CPUHP callbacks to avoid race condition
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index cf4f9f2e1807..0650bcdff410 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -1016,6 +1016,7 @@ struct etmv4_save_state {
  *		   the trace unit.
  * @arch_features: Bitmap of arch features of etmv4 devices.
  * @mmio_external: True if ETM considers MMIO an external access.
+ * @no_quad_mmio:  True if ETM does not support 64-bit (quad) access.
  */
 struct etmv4_drvdata {
 	void __iomem			*base;
@@ -1069,6 +1070,7 @@ struct etmv4_drvdata {
 	bool				skip_power_up;
 	DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
 	bool				mmio_external;
+	bool				no_quad_mmio;
 };
 
 /* Address comparator access types */
@@ -1093,6 +1095,36 @@ void etm4_config_trace_mode(struct etmv4_config *config);
 u64 etm4x_sysreg_read(u32 offset, bool _relaxed, bool _64bit);
 void etm4x_sysreg_write(u64 val, u32 offset, bool _relaxed, bool _64bit);
 
+/* 64-bit aligned to convert 64-bit access to 2 ea. 32-bit access */
+#pragma pack(push, 8)
+
+struct etm_quad_split {
+	u32 lsw;
+	u32 msw;
+};
+
+#pragma pack(pop)
+
+static inline u64 etm4x_split_read64(struct csdev_access *csa, unsigned int offset)
+{
+	struct etm_quad_split container;
+
+	container.lsw = etm4x_read32(csa, offset);
+	container.msw = etm4x_read32(csa, offset + sizeof(u32));
+
+	return *(u64 *) &container;
+}
+
+static inline void etm4x_split_write64(struct csdev_access *csa, u64 quad, unsigned int offset)
+{
+	struct etm_quad_split container;
+
+	*(u64 *) &container = quad;
+
+	etm4x_relaxed_write32(csa, container.lsw, offset);
+	etm4x_relaxed_write32(csa, container.msw, offset + sizeof(u32));
+}
+
 static inline bool etm4x_is_ete(struct etmv4_drvdata *drvdata)
 {
 	return drvdata->arch >= ETM_ARCH_ETE;
-- 
2.25.1


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[PATCH 3/3] coresight etm4x: Add pr_debug statement for Coresight component PID/CID

[Steve Clevenger]

Add pr_debug statement to provide visibility into Coresight component PID
and CID settings. This helped debug an intermittent clock related issue
resulting in bad PID/CID values.

Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
---
 drivers/amba/bus.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index ff7454a38058..7c432442862c 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -136,6 +136,7 @@ static int amba_read_periphid(struct amba_device *dev)
 	u32 size, pid, cid;
 	void __iomem *tmp;
 	int i, ret;
+	u32 cid_addr, pid_addr;
 
 	ret = dev_pm_domain_attach(&dev->dev, true);
 	if (ret) {
@@ -178,6 +179,12 @@ static int amba_read_periphid(struct amba_device *dev)
 	for (cid = 0, i = 0; i < 4; i++)
 		cid |= (readl(tmp + size - 0x10 + 4 * i) & 255) << (i * 8);
 
+	/* physical address as meaningful */
+	cid_addr = (u64)(dev->res.start + size - 0x20);
+	pid_addr = (u64)(dev->res.start + size - 0x10);
+
+	pr_debug("pid  (%llX): %08X  cid  (%llX): %08X\n", pid_addr, pid, cid_addr, cid);
+
 	if (cid == CORESIGHT_CID) {
 		/* set the base to the start of the last 4k block */
 		void __iomem *csbase = tmp + size - 4096;
-- 
2.25.1


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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Suzuki K Poulose]

Hi Steve

Thanks for the patches. Have a few comments below.

On 20/01/2023 00:51, Steve Clevenger wrote:
> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
> Computing design decision MMIO reads are considered the same as an
> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
> is valid regardless of TRCOSLAR.OSLK provided MMIO access
> (now deprecated) is supported.
> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation

Please could you add this erratum to the :

Documentation/arm64/silicon-errata.rst ?

Given the ETM is v4.6, doesn't it support system instructions and
that is causing this issue of "MMIO access is considered external" ?
If it does, I think we should drop all of this and simply wire the
system instruction access support.

> 
> Add Ampere ETM PID required for Coresight ETM driver support.
> 
> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
> ---
>   .../coresight/coresight-etm4x-core.c          | 36 +++++++++++++++----
>   drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
>   2 files changed, 32 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 1cc052979e01..533be1928a09 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
>   	drvdata = dev_get_drvdata(init_arg->dev);
>   	csa = init_arg->csa;
>   
> +	/* Detect the support for OS Lock before we actually use it */
> +	etm_detect_os_lock(drvdata, csa);
> + > +	/*
> +	 * For ETM implementations that consider MMIO an external access
> +	 * clear TRCOSLAR.OSLK early.
> +	 */
> +	if (drvdata->mmio_external)
> +		etm4_os_unlock_csa(drvdata, csa);
> +
>   	/*
>   	 * If we are unable to detect the access mechanism,
>   	 * or unable to detect the trace unit type, fail
> -	 * early.
> +	 * early. Reset TRCOSLAR.OSLK if cleared.
>   	 */
> -	if (!etm4_init_csdev_access(drvdata, csa))
> +	if (!etm4_init_csdev_access(drvdata, csa)) {
> +		if (drvdata->mmio_external)
> +			etm4_os_lock(drvdata);

Couldn't this unlock/lock sequence be moved into the 
etm4_init_csdev_iomem_access() where it actually matters ?

Or thinking more about it, we could actually move the unlock step early
for all ETMs irrespective of whether they are affected by this erratum.
Of course, putting this back, if we fail to detect the ETM properly.
I don't see any issue with that.

>   		return;
> +	}
>   
> -	/* Detect the support for OS Lock before we actually use it */
> -	etm_detect_os_lock(drvdata, csa);
> +	/*
> +	 * Make sure all registers are accessible
> +	 * TRCOSLAR.OSLK may already be clear
> +	 */
> +	if (!drvdata->mmio_external)
> +		etm4_os_unlock_csa(drvdata, csa);
>   
> -	/* Make sure all registers are accessible */
> -	etm4_os_unlock_csa(drvdata, csa);
>   	etm4_cs_unlock(drvdata, csa);
>   
>   	etm4_check_arch_features(drvdata, init_arg->pid);
> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
>   	init_arg.csa = &access;
>   	init_arg.pid = etm_pid;
>   
> +	/*
> +	 * Ampere ETM v4.6 considers MMIO access as external. This mask
> +	 * isolates the manufacturer JEP106 ID in the PID.
> +	 * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
> +	 */

Does it affect all Ampere ETMs ? You seem to be ignoring the 
PDIR1.PART_1, PDIR0_PART_0 fields, which happens to be 0.

> +	if ((init_arg.pid & 0x000FF000) == 0x00096000)
> +		drvdata->mmio_external = true;
Like I said, we may be able to get rid of this flag and do the step for 
all ETMs. But before all of that, I would like to see if this is problem
because we are skipping the system instruction route.

Suzuki

>   	/*
>   	 * Serialize against CPUHP callbacks to avoid race condition
>   	 * between the smp call and saving the delayed probe.
> @@ -2192,6 +2215,7 @@ static const struct amba_id etm4_ids[] = {
>   	CS_AMBA_ID(0x000bb95e),			/* Cortex-A57 */
>   	CS_AMBA_ID(0x000bb95a),			/* Cortex-A72 */
>   	CS_AMBA_ID(0x000bb959),			/* Cortex-A73 */
> +	CS_AMBA_UCI_ID(0x00096000, uci_id_etm4),/* Ampere ARMv8 */
>   	CS_AMBA_UCI_ID(0x000bb9da, uci_id_etm4),/* Cortex-A35 */
>   	CS_AMBA_UCI_ID(0x000bbd05, uci_id_etm4),/* Cortex-A55 */
>   	CS_AMBA_UCI_ID(0x000bbd0a, uci_id_etm4),/* Cortex-A75 */
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> index 4b21bb79f168..cf4f9f2e1807 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> @@ -1015,6 +1015,7 @@ struct etmv4_save_state {
>    * @skip_power_up: Indicates if an implementation can skip powering up
>    *		   the trace unit.
>    * @arch_features: Bitmap of arch features of etmv4 devices.
> + * @mmio_external: True if ETM considers MMIO an external access.
>    */
>   struct etmv4_drvdata {
>   	void __iomem			*base;
> @@ -1067,6 +1068,7 @@ struct etmv4_drvdata {
>   	bool				state_needs_restore;
>   	bool				skip_power_up;
>   	DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
> +	bool				mmio_external;
>   };
>   
>   /* Address comparator access types */


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Re: [PATCH 2/3] coresight etm4x: Add 32-bit read/write option to split 64-bit words

[Suzuki K Poulose]

On 20/01/2023 00:51, Steve Clevenger wrote:
> Add 32-bit read/write access option for Ampere ETMv4.6 64-bit registers.
> Ampere Computing erratum AC03_DEBUG_10 describes a design decision where
> 64-bit read/write access is not supported for the ETMv4.6 implementation.
> These 64-bit registers must be accessed as 2 ea. 32-bit registers.
> AC03_DEBUG_10 is described in the AmpereOne Developer Errata:
> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation

As with the previous comment, please :
   a) If this is because of the system instruction access support
   b) Document the erratum

> 
> Fix drvdata->nr_addr_cmp for() loop range bug to drvdata->nr_addr_cmp * 2
> in etm_enable_hw.

Good catch ! Please separate this out and send it as a fix. I can queue 
this.

> 
> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
> ---
>   .../coresight/coresight-etm4x-core.c          | 81 ++++++++++++++-----
>   drivers/hwtracing/coresight/coresight-etm4x.h | 32 ++++++++
>   2 files changed, 93 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 533be1928a09..bf4daa649cdf 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -452,18 +452,31 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
>   		if (etm4x_sspcicrn_present(drvdata, i))
>   			etm4x_relaxed_write32(csa, config->ss_pe_cmp[i], TRCSSPCICRn(i));
>   	}
> -	for (i = 0; i < drvdata->nr_addr_cmp; i++) {
> -		etm4x_relaxed_write64(csa, config->addr_val[i], TRCACVRn(i));
> -		etm4x_relaxed_write64(csa, config->addr_acc[i], TRCACATRn(i));
> +	for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
> +		if (drvdata->no_quad_mmio) {
> +			etm4x_split_write64(csa, config->addr_val[i], TRCACVRn(i));
> +			etm4x_split_write64(csa, config->addr_acc[i], TRCACATRn(i));
> +		} else {
> +			etm4x_relaxed_write64(csa, config->addr_val[i], TRCACVRn(i));
> +			etm4x_relaxed_write64(csa, config->addr_acc[i], TRCACATRn(i));
> +		}
> +	}

Something like this can be leave some places out. I think we could hide 
it under the generic helpers and handle it there. May be "struct 
csdev_access" can cache this "no_quad_mmio" and do the right thing ?


> +	for (i = 0; i < drvdata->numcidc; i++) {
> +		if (drvdata->no_quad_mmio)
> +			etm4x_split_write64(csa, config->ctxid_pid[i], TRCCIDCVRn(i));
> +		else
> +			etm4x_relaxed_write64(csa, config->ctxid_pid[i], TRCCIDCVRn(i));
>   	}
> -	for (i = 0; i < drvdata->numcidc; i++)
> -		etm4x_relaxed_write64(csa, config->ctxid_pid[i], TRCCIDCVRn(i));
>   	etm4x_relaxed_write32(csa, config->ctxid_mask0, TRCCIDCCTLR0);
>   	if (drvdata->numcidc > 4)
>   		etm4x_relaxed_write32(csa, config->ctxid_mask1, TRCCIDCCTLR1);
>   
> -	for (i = 0; i < drvdata->numvmidc; i++)
> -		etm4x_relaxed_write64(csa, config->vmid_val[i], TRCVMIDCVRn(i));
> +	for (i = 0; i < drvdata->numvmidc; i++) {
> +		if (drvdata->no_quad_mmio)
> +			etm4x_split_write64(csa, config->vmid_val[i], TRCVMIDCVRn(i));
> +		else
> +			etm4x_relaxed_write64(csa, config->vmid_val[i], TRCVMIDCVRn(i));
> +	}
>   	etm4x_relaxed_write32(csa, config->vmid_mask0, TRCVMIDCCTLR0);
>   	if (drvdata->numvmidc > 4)
>   		etm4x_relaxed_write32(csa, config->vmid_mask1, TRCVMIDCCTLR1);
> @@ -1670,8 +1683,13 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
>   	}
>   
>   	for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
> -		state->trcacvr[i] = etm4x_read64(csa, TRCACVRn(i));
> -		state->trcacatr[i] = etm4x_read64(csa, TRCACATRn(i));
> +		if (drvdata->no_quad_mmio) {
> +			state->trcacvr[i] = etm4x_split_read64(csa, TRCACVRn(i));
> +			state->trcacatr[i] = etm4x_split_read64(csa, TRCACATRn(i));
> +		} else {
> +			state->trcacvr[i] = etm4x_read64(csa, TRCACVRn(i));
> +			state->trcacatr[i] = etm4x_read64(csa, TRCACATRn(i));
> +		}
>   	}
>   
>   	/*
> @@ -1681,11 +1699,19 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
>   	 * unit") of ARM IHI 0064D.
>   	 */
>   
> -	for (i = 0; i < drvdata->numcidc; i++)
> -		state->trccidcvr[i] = etm4x_read64(csa, TRCCIDCVRn(i));
> +	for (i = 0; i < drvdata->numcidc; i++) {
> +		if (drvdata->no_quad_mmio)
> +			state->trccidcvr[i] = etm4x_split_read64(csa, TRCCIDCVRn(i));
> +		else
> +			state->trccidcvr[i] = etm4x_read64(csa, TRCCIDCVRn(i));
> +	}
>   
> -	for (i = 0; i < drvdata->numvmidc; i++)
> -		state->trcvmidcvr[i] = etm4x_read64(csa, TRCVMIDCVRn(i));
> +	for (i = 0; i < drvdata->numvmidc; i++) {
> +		if (drvdata->no_quad_mmio)
> +			state->trcvmidcvr[i] = etm4x_split_read64(csa, TRCVMIDCVRn(i));
> +		else
> +			state->trcvmidcvr[i] = etm4x_read64(csa, TRCVMIDCVRn(i));
> +	}
>   
>   	state->trccidcctlr0 = etm4x_read32(csa, TRCCIDCCTLR0);
>   	if (drvdata->numcidc > 4)
> @@ -1799,15 +1825,28 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
>   	}
>   
>   	for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
> -		etm4x_relaxed_write64(csa, state->trcacvr[i], TRCACVRn(i));
> -		etm4x_relaxed_write64(csa, state->trcacatr[i], TRCACATRn(i));
> +		if (drvdata->no_quad_mmio) {
> +			etm4x_split_write64(csa, state->trcacvr[i], TRCACVRn(i));
> +			etm4x_split_write64(csa, state->trcacatr[i], TRCACATRn(i));
> +		} else {
> +			etm4x_relaxed_write64(csa, state->trcacvr[i], TRCACVRn(i));
> +			etm4x_relaxed_write64(csa, state->trcacatr[i], TRCACATRn(i));
> +		}
>   	}
>   
> -	for (i = 0; i < drvdata->numcidc; i++)
> -		etm4x_relaxed_write64(csa, state->trccidcvr[i], TRCCIDCVRn(i));
> +	for (i = 0; i < drvdata->numcidc; i++) {
> +		if (drvdata->no_quad_mmio)
> +			etm4x_split_write64(csa, state->trccidcvr[i], TRCCIDCVRn(i));
> +		else
> +			etm4x_relaxed_write64(csa, state->trccidcvr[i], TRCCIDCVRn(i));
> +	}
>   
> -	for (i = 0; i < drvdata->numvmidc; i++)
> -		etm4x_relaxed_write64(csa, state->trcvmidcvr[i], TRCVMIDCVRn(i));
> +	for (i = 0; i < drvdata->numvmidc; i++) {
> +		if (drvdata->no_quad_mmio)
> +			etm4x_split_write64(csa, state->trcvmidcvr[i], TRCVMIDCVRn(i));
> +		else
> +			etm4x_relaxed_write64(csa, state->trcvmidcvr[i], TRCVMIDCVRn(i));
> +	}
>   
>   	etm4x_relaxed_write32(csa, state->trccidcctlr0, TRCCIDCCTLR0);
>   	if (drvdata->numcidc > 4)
> @@ -2047,8 +2086,10 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
>   	 * isolates the manufacturer JEP106 ID in the PID.
>   	 * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>   	 */
> -	if ((init_arg.pid & 0x000FF000) == 0x00096000)
> +	if ((init_arg.pid & 0x000FF000) == 0x00096000) {
>   		drvdata->mmio_external = true;
> +		drvdata->no_quad_mmio = true;
> +	}
>   
>   	/*
>   	 * Serialize against CPUHP callbacks to avoid race condition
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> index cf4f9f2e1807..0650bcdff410 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> @@ -1016,6 +1016,7 @@ struct etmv4_save_state {
>    *		   the trace unit.
>    * @arch_features: Bitmap of arch features of etmv4 devices.
>    * @mmio_external: True if ETM considers MMIO an external access.
> + * @no_quad_mmio:  True if ETM does not support 64-bit (quad) access.
>    */
>   struct etmv4_drvdata {
>   	void __iomem			*base;
> @@ -1069,6 +1070,7 @@ struct etmv4_drvdata {
>   	bool				skip_power_up;
>   	DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
>   	bool				mmio_external;
> +	bool				no_quad_mmio;
>   };
>   
>   /* Address comparator access types */
> @@ -1093,6 +1095,36 @@ void etm4_config_trace_mode(struct etmv4_config *config);
>   u64 etm4x_sysreg_read(u32 offset, bool _relaxed, bool _64bit);
>   void etm4x_sysreg_write(u64 val, u32 offset, bool _relaxed, bool _64bit);
>   
> +/* 64-bit aligned to convert 64-bit access to 2 ea. 32-bit access */
> +#pragma pack(push, 8)
> +
> +struct etm_quad_split {
> +	u32 lsw;
> +	u32 msw;
> +};
> +
> +#pragma pack(pop)
> +
> +static inline u64 etm4x_split_read64(struct csdev_access *csa, unsigned int offset)
> +{
> +	struct etm_quad_split container;
> +
> +	container.lsw = etm4x_read32(csa, offset);
> +	container.msw = etm4x_read32(csa, offset + sizeof(u32));
> +
> +	return *(u64 *) &container;

Wouldn't this break with the "endianness" flip ? (Not that we have BE 
implementations). Could we not combine the two values to a 64bit value 
and pass that instead ?

Similarly below.

Suzuki

> +}
> +
> +static inline void etm4x_split_write64(struct csdev_access *csa, u64 quad, unsigned int offset)
> +{
> +	struct etm_quad_split container;
> +
> +	*(u64 *) &container = quad;
> +
> +	etm4x_relaxed_write32(csa, container.lsw, offset);
> +	etm4x_relaxed_write32(csa, container.msw, offset + sizeof(u32));
> +}
> +
>   static inline bool etm4x_is_ete(struct etmv4_drvdata *drvdata)
>   {
>   	return drvdata->arch >= ETM_ARCH_ETE;


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Re: [PATCH 3/3] coresight etm4x: Add pr_debug statement for Coresight component PID/CID

[Suzuki K Poulose]

Cc: Russell

nit: Subject line doesn't match the patch. This could be :

  "amba: bus: Add pr_debug for AMBA PID/CID"

On 20/01/2023 00:51, Steve Clevenger wrote:
> Add pr_debug statement to provide visibility into Coresight component PID
> and CID settings. This helped debug an intermittent clock related issue
> resulting in bad PID/CID values.

And this change belongs to the AMBA subsystem. Please run :

scripts/get_maintainer.pl on your patch and add the necessary people 
from that list for your patch.

As such, I don't think brings any value to be added to the tree.
I will leave it for the maintainers to comment.

Suzuki

> 
> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
> ---
>   drivers/amba/bus.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index ff7454a38058..7c432442862c 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -136,6 +136,7 @@ static int amba_read_periphid(struct amba_device *dev)
>   	u32 size, pid, cid;
>   	void __iomem *tmp;
>   	int i, ret;
> +	u32 cid_addr, pid_addr;
>   
>   	ret = dev_pm_domain_attach(&dev->dev, true);
>   	if (ret) {
> @@ -178,6 +179,12 @@ static int amba_read_periphid(struct amba_device *dev)
>   	for (cid = 0, i = 0; i < 4; i++)
>   		cid |= (readl(tmp + size - 0x10 + 4 * i) & 255) << (i * 8);
>   
> +	/* physical address as meaningful */
> +	cid_addr = (u64)(dev->res.start + size - 0x20);
> +	pid_addr = (u64)(dev->res.start + size - 0x10);
> +
> +	pr_debug("pid  (%llX): %08X  cid  (%llX): %08X\n", pid_addr, pid, cid_addr, cid);
> +
>   	if (cid == CORESIGHT_CID) {
>   		/* set the base to the start of the last 4k block */
>   		void __iomem *csbase = tmp + size - 4096;


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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Mike Leach]

Hi Steve,

On Fri, 20 Jan 2023 at 00:52, Steve Clevenger
<scclevenger@os.amperecomputing.com> wrote:
>
> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
> Computing design decision MMIO reads are considered the same as an
> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
> is valid regardless of TRCOSLAR.OSLK provided MMIO access
> (now deprecated) is supported.
> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>
> Add Ampere ETM PID required for Coresight ETM driver support.
>
> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
> ---
>  .../coresight/coresight-etm4x-core.c          | 36 +++++++++++++++----
>  drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
>  2 files changed, 32 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 1cc052979e01..533be1928a09 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
>         drvdata = dev_get_drvdata(init_arg->dev);
>         csa = init_arg->csa;
>

As far as I can tell there appears to be an initialisation issue here.
etm_probe()
...
struct csdev_access access = { 0 };
...
init_arg.csa = &access

::call=> etm4_init_arch_data(init_arg)

Thus csa is uninitialised?

> +       /* Detect the support for OS Lock before we actually use it */
> +       etm_detect_os_lock(drvdata, csa);
> +
> +       /*
> +        * For ETM implementations that consider MMIO an external access
> +        * clear TRCOSLAR.OSLK early.
> +        */
> +       if (drvdata->mmio_external)
> +               etm4_os_unlock_csa(drvdata, csa);
> +
>         /*
>          * If we are unable to detect the access mechanism,
>          * or unable to detect the trace unit type, fail
> -        * early.
> +        * early. Reset TRCOSLAR.OSLK if cleared.
>          */
> -       if (!etm4_init_csdev_access(drvdata, csa))
> +       if (!etm4_init_csdev_access(drvdata, csa)) {

This call initialises csa according to sysreg / iomem access requirements



> +               if (drvdata->mmio_external)
> +                       etm4_os_lock(drvdata);
>                 return;
> +       }
>
> -       /* Detect the support for OS Lock before we actually use it */
> -       etm_detect_os_lock(drvdata, csa);
> +       /*
> +        * Make sure all registers are accessible
> +        * TRCOSLAR.OSLK may already be clear
> +        */
> +       if (!drvdata->mmio_external)
> +               etm4_os_unlock_csa(drvdata, csa);
>
> -       /* Make sure all registers are accessible */
> -       etm4_os_unlock_csa(drvdata, csa);
>         etm4_cs_unlock(drvdata, csa);
>
>         etm4_check_arch_features(drvdata, init_arg->pid);
> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
>         init_arg.csa = &access;
>         init_arg.pid = etm_pid;
>
> +       /*
> +        * Ampere ETM v4.6 considers MMIO access as external. This mask
> +        * isolates the manufacturer JEP106 ID in the PID.
> +        * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
> +        */
> +       if ((init_arg.pid & 0x000FF000) == 0x00096000)
> +               drvdata->mmio_external = true;
> +
>         /*
>          * Serialize against CPUHP callbacks to avoid race condition
>          * between the smp call and saving the delayed probe.
> @@ -2192,6 +2215,7 @@ static const struct amba_id etm4_ids[] = {
>         CS_AMBA_ID(0x000bb95e),                 /* Cortex-A57 */
>         CS_AMBA_ID(0x000bb95a),                 /* Cortex-A72 */
>         CS_AMBA_ID(0x000bb959),                 /* Cortex-A73 */
> +       CS_AMBA_UCI_ID(0x00096000, uci_id_etm4),/* Ampere ARMv8 */
>         CS_AMBA_UCI_ID(0x000bb9da, uci_id_etm4),/* Cortex-A35 */
>         CS_AMBA_UCI_ID(0x000bbd05, uci_id_etm4),/* Cortex-A55 */
>         CS_AMBA_UCI_ID(0x000bbd0a, uci_id_etm4),/* Cortex-A75 */
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> index 4b21bb79f168..cf4f9f2e1807 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> @@ -1015,6 +1015,7 @@ struct etmv4_save_state {
>   * @skip_power_up: Indicates if an implementation can skip powering up
>   *                the trace unit.
>   * @arch_features: Bitmap of arch features of etmv4 devices.
> + * @mmio_external: True if ETM considers MMIO an external access.
>   */
>  struct etmv4_drvdata {
>         void __iomem                    *base;
> @@ -1067,6 +1068,7 @@ struct etmv4_drvdata {
>         bool                            state_needs_restore;
>         bool                            skip_power_up;
>         DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);

Rather than continue to add bools - is it not worthwhile adding to the
bitmap above and extending the arch features API to allow a
"has_feature" call?

> +       bool                            mmio_external;
>  };
>
>  /* Address comparator access types */
> --
> 2.25.1
>
Regards

Mike
-- 
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Manchester Design Centre. UK

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Re: [PATCH 3/3] coresight etm4x: Add pr_debug statement for Coresight component PID/CID

[Russell King (Oracle)]

On Fri, Jan 20, 2023 at 11:23:53AM +0000, Suzuki K Poulose wrote:
> 
> Cc: Russell
> 
> nit: Subject line doesn't match the patch. This could be :
> 
>  "amba: bus: Add pr_debug for AMBA PID/CID"
> 
> On 20/01/2023 00:51, Steve Clevenger wrote:
> > Add pr_debug statement to provide visibility into Coresight component PID
> > and CID settings. This helped debug an intermittent clock related issue
> > resulting in bad PID/CID values.
> 
> And this change belongs to the AMBA subsystem. Please run :
> 
> scripts/get_maintainer.pl on your patch and add the necessary people from
> that list for your patch.
> 
> As such, I don't think brings any value to be added to the tree.
> I will leave it for the maintainers to comment.

Looking at the context in this patch, I see code that is reading at
least the CID but likely also the PID from the device, duplicating
the code that is already in the bus layer, and stored in the
amba_device's periphid and cid members...

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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Steve Clevenger]

Hi Suzuki,

Comments in-line. Please note the approach I attempted while adding in
the Ampere support was to otherwise not disturb existing driver code for
non-Ampere parts.

Steve

On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
> Hi Steve
> 
> Thanks for the patches. Have a few comments below.
> 
> On 20/01/2023 00:51, Steve Clevenger wrote:
>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>> Computing design decision MMIO reads are considered the same as an
>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>> (now deprecated) is supported.
>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
> 
> Please could you add this erratum to the :
> 
> Documentation/arm64/silicon-errata.rst ?
> 
> Given the ETM is v4.6, doesn't it support system instructions and
> that is causing this issue of "MMIO access is considered external" ?
> If it does, I think we should drop all of this and simply wire the
> system instruction access support.
That's not the issue in this case. This MMIO access should've been
allowed by the Ampere ETMv4.6 implementation.  Based on comments I've
read in the driver code, the MMIO read access to TRCIDR1 occurs after a
TRCDEVARCH access. The comments suggest this was to accommodate
potentially unreliable TRCDEVARCH (and TRCIDR1) values. This Ampere
ETMv4.6 allows an MMIO access to TRCDEVARCH, but not to TRCIDR1 unless
the TRCOSLAR.OSLK lock is cleared first.

> 
>>
>> Add Ampere ETM PID required for Coresight ETM driver support.
>>
>> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
>> ---
>>   .../coresight/coresight-etm4x-core.c          | 36 +++++++++++++++----
>>   drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
>>   2 files changed, 32 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> index 1cc052979e01..533be1928a09 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
>>       drvdata = dev_get_drvdata(init_arg->dev);
>>       csa = init_arg->csa;
>>   +    /* Detect the support for OS Lock before we actually use it */
>> +    etm_detect_os_lock(drvdata, csa);
>> + > +    /*
>> +     * For ETM implementations that consider MMIO an external access
>> +     * clear TRCOSLAR.OSLK early.
>> +     */
>> +    if (drvdata->mmio_external)
>> +        etm4_os_unlock_csa(drvdata, csa);
>> +
>>       /*
>>        * If we are unable to detect the access mechanism,
>>        * or unable to detect the trace unit type, fail
>> -     * early.
>> +     * early. Reset TRCOSLAR.OSLK if cleared.
>>        */
>> -    if (!etm4_init_csdev_access(drvdata, csa))
>> +    if (!etm4_init_csdev_access(drvdata, csa)) {
>> +        if (drvdata->mmio_external)
>> +            etm4_os_lock(drvdata);
> 
> Couldn't this unlock/lock sequence be moved into the
> etm4_init_csdev_iomem_access() where it actually matters ?
> 
> Or thinking more about it, we could actually move the unlock step early
> for all ETMs irrespective of whether they are affected by this erratum.
> Of course, putting this back, if we fail to detect the ETM properly.
> I don't see any issue with that.
I agree the lock could be cleared earlier in the code. That's what this
patch does for Ampere. If it's decided ok to do for other (or all)
manufacturers, then the Ampere specific ID check goes away in this
place. The Ampere ID check (and flag) to determine whether the [Patch
2/3] 64-bit access is split into 2 ea. 32-bit accesses would remain, or
use an existing feature mask as suggested by Mike Leach in a later review.

> 
>>           return;
>> +    }
>>   -    /* Detect the support for OS Lock before we actually use it */
>> -    etm_detect_os_lock(drvdata, csa);
>> +    /*
>> +     * Make sure all registers are accessible
>> +     * TRCOSLAR.OSLK may already be clear
>> +     */
>> +    if (!drvdata->mmio_external)
>> +        etm4_os_unlock_csa(drvdata, csa);
>>   -    /* Make sure all registers are accessible */
>> -    etm4_os_unlock_csa(drvdata, csa);
>>       etm4_cs_unlock(drvdata, csa);
>>         etm4_check_arch_features(drvdata, init_arg->pid);
>> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void
>> __iomem *base, u32 etm_pid)
>>       init_arg.csa = &access;
>>       init_arg.pid = etm_pid;
>>   +    /*
>> +     * Ampere ETM v4.6 considers MMIO access as external. This mask
>> +     * isolates the manufacturer JEP106 ID in the PID.
>> +     * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>> +     */
> 
> Does it affect all Ampere ETMs ? You seem to be ignoring the
> PDIR1.PART_1, PDIR0_PART_0 fields, which happens to be 0.
This is the first Ampere ETMv4.x implementation. I wrote the ID check
like this specifically because Ampere does not intend to address this
for ETM designs in progress.

> 
>> +    if ((init_arg.pid & 0x000FF000) == 0x00096000)
>> +        drvdata->mmio_external = true;
> Like I said, we may be able to get rid of this flag and do the step for
> all ETMs. But before all of that, I would like to see if this is problem
> because we are skipping the system instruction route.
> 
We understand MMIO access is deprecated going forward. There is other
Linux code to be concerned about. For example, AMBA code reads the
component PID/CID. This discovery code uses mapped values digested from
the CoreSight ACPI which are the descriptions and graphs for the
manufacturer trace implementation. There may be other Linux code I'm not
aware. Note the ASL examples in ARM Document number: DEN0067 specify
MMIO locations for every CoreSight component.

> Suzuki
> 
>>       /*
>>        * Serialize against CPUHP callbacks to avoid race condition
>>        * between the smp call and saving the delayed probe.
>> @@ -2192,6 +2215,7 @@ static const struct amba_id etm4_ids[] = {
>>       CS_AMBA_ID(0x000bb95e),            /* Cortex-A57 */
>>       CS_AMBA_ID(0x000bb95a),            /* Cortex-A72 */
>>       CS_AMBA_ID(0x000bb959),            /* Cortex-A73 */
>> +    CS_AMBA_UCI_ID(0x00096000, uci_id_etm4),/* Ampere ARMv8 */
>>       CS_AMBA_UCI_ID(0x000bb9da, uci_id_etm4),/* Cortex-A35 */
>>       CS_AMBA_UCI_ID(0x000bbd05, uci_id_etm4),/* Cortex-A55 */
>>       CS_AMBA_UCI_ID(0x000bbd0a, uci_id_etm4),/* Cortex-A75 */
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h
>> b/drivers/hwtracing/coresight/coresight-etm4x.h
>> index 4b21bb79f168..cf4f9f2e1807 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
>> @@ -1015,6 +1015,7 @@ struct etmv4_save_state {
>>    * @skip_power_up: Indicates if an implementation can skip powering up
>>    *           the trace unit.
>>    * @arch_features: Bitmap of arch features of etmv4 devices.
>> + * @mmio_external: True if ETM considers MMIO an external access.
>>    */
>>   struct etmv4_drvdata {
>>       void __iomem            *base;
>> @@ -1067,6 +1068,7 @@ struct etmv4_drvdata {
>>       bool                state_needs_restore;
>>       bool                skip_power_up;
>>       DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
>> +    bool                mmio_external;
>>   };
>>     /* Address comparator access types */
> 

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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Steve Clevenger]

Hi Mike,

Comments in-line.

Steve

On 1/20/2023 3:45 AM, Mike Leach wrote:
> Hi Steve,
> 
> On Fri, 20 Jan 2023 at 00:52, Steve Clevenger
> <scclevenger@os.amperecomputing.com> wrote:
>>
>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>> Computing design decision MMIO reads are considered the same as an
>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>> (now deprecated) is supported.
>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>
>> Add Ampere ETM PID required for Coresight ETM driver support.
>>
>> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
>> ---
>>  .../coresight/coresight-etm4x-core.c          | 36 +++++++++++++++----
>>  drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
>>  2 files changed, 32 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> index 1cc052979e01..533be1928a09 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
>>         drvdata = dev_get_drvdata(init_arg->dev);
>>         csa = init_arg->csa;
>>
> 
> As far as I can tell there appears to be an initialisation issue here.
> etm_probe()
> ...
> struct csdev_access access = { 0 };
> ...
> init_arg.csa = &access
> 
> ::call=> etm4_init_arch_data(init_arg)
> 
> Thus csa is uninitialised?
It looks to me csa is intended to be initialized to zero? In any case,
the Ampere check uses only the ETM pid, which is initialized directly above.

> 
>> +       /* Detect the support for OS Lock before we actually use it */
>> +       etm_detect_os_lock(drvdata, csa);
>> +
>> +       /*
>> +        * For ETM implementations that consider MMIO an external access
>> +        * clear TRCOSLAR.OSLK early.
>> +        */
>> +       if (drvdata->mmio_external)
>> +               etm4_os_unlock_csa(drvdata, csa);
>> +
>>         /*
>>          * If we are unable to detect the access mechanism,
>>          * or unable to detect the trace unit type, fail
>> -        * early.
>> +        * early. Reset TRCOSLAR.OSLK if cleared.
>>          */
>> -       if (!etm4_init_csdev_access(drvdata, csa))
>> +       if (!etm4_init_csdev_access(drvdata, csa)) {
> 
> This call initialises csa according to sysreg / iomem access requirements
csa is initialized only when no drvdata->base exists. Under what
circumstance would there be no ETM base given the recommended CoreSight
ACPI implementation? See the examples in ARM Document number: DEN0067.
> 
> 
> 
>> +               if (drvdata->mmio_external)
>> +                       etm4_os_lock(drvdata);
>>                 return;
>> +       }
>>
>> -       /* Detect the support for OS Lock before we actually use it */
>> -       etm_detect_os_lock(drvdata, csa);
>> +       /*
>> +        * Make sure all registers are accessible
>> +        * TRCOSLAR.OSLK may already be clear
>> +        */
>> +       if (!drvdata->mmio_external)
>> +               etm4_os_unlock_csa(drvdata, csa);
>>
>> -       /* Make sure all registers are accessible */
>> -       etm4_os_unlock_csa(drvdata, csa);
>>         etm4_cs_unlock(drvdata, csa);
>>
>>         etm4_check_arch_features(drvdata, init_arg->pid);
>> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
>>         init_arg.csa = &access;
>>         init_arg.pid = etm_pid;
>>
>> +       /*
>> +        * Ampere ETM v4.6 considers MMIO access as external. This mask
>> +        * isolates the manufacturer JEP106 ID in the PID.
>> +        * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>> +        */
>> +       if ((init_arg.pid & 0x000FF000) == 0x00096000)
>> +               drvdata->mmio_external = true;
>> +
>>         /*
>>          * Serialize against CPUHP callbacks to avoid race condition
>>          * between the smp call and saving the delayed probe.
>> @@ -2192,6 +2215,7 @@ static const struct amba_id etm4_ids[] = {
>>         CS_AMBA_ID(0x000bb95e),                 /* Cortex-A57 */
>>         CS_AMBA_ID(0x000bb95a),                 /* Cortex-A72 */
>>         CS_AMBA_ID(0x000bb959),                 /* Cortex-A73 */
>> +       CS_AMBA_UCI_ID(0x00096000, uci_id_etm4),/* Ampere ARMv8 */
>>         CS_AMBA_UCI_ID(0x000bb9da, uci_id_etm4),/* Cortex-A35 */
>>         CS_AMBA_UCI_ID(0x000bbd05, uci_id_etm4),/* Cortex-A55 */
>>         CS_AMBA_UCI_ID(0x000bbd0a, uci_id_etm4),/* Cortex-A75 */
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
>> index 4b21bb79f168..cf4f9f2e1807 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
>> @@ -1015,6 +1015,7 @@ struct etmv4_save_state {
>>   * @skip_power_up: Indicates if an implementation can skip powering up
>>   *                the trace unit.
>>   * @arch_features: Bitmap of arch features of etmv4 devices.
>> + * @mmio_external: True if ETM considers MMIO an external access.
>>   */
>>  struct etmv4_drvdata {
>>         void __iomem                    *base;
>> @@ -1067,6 +1068,7 @@ struct etmv4_drvdata {
>>         bool                            state_needs_restore;
>>         bool                            skip_power_up;
>>         DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
> 
> Rather than continue to add bools - is it not worthwhile adding to the
> bitmap above and extending the arch features API to allow a
> "has_feature" call?
I can look into this. I agree using a bool for every exception doesn't
scale well. Referring to one Suzuki Poulose review comment, his proposal
to clear TRCOSLAR.OSLK early for all parts would mean one of these bools
could go away. Otherwise, possibly add one (or more) bit definitions for
use by the etm4_disable_arch_specific call. The order of this call would
need to change, depending.

> 
>> +       bool                            mmio_external;
>>  };
>>
>>  /* Address comparator access types */
>> --
>> 2.25.1
>>
> Regards
> 
> Mike

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Re: [PATCH 3/3] coresight etm4x: Add pr_debug statement for Coresight component PID/CID

[Steve Clevenger]

Hi Russell,

Comments inline.

Steve

On 1/20/2023 4:40 AM, Russell King (Oracle) wrote:
> On Fri, Jan 20, 2023 at 11:23:53AM +0000, Suzuki K Poulose wrote:
>>
>> Cc: Russell
>>
>> nit: Subject line doesn't match the patch. This could be :
>>
>>  "amba: bus: Add pr_debug for AMBA PID/CID"
>>
>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>> Add pr_debug statement to provide visibility into Coresight component PID
>>> and CID settings. This helped debug an intermittent clock related issue
>>> resulting in bad PID/CID values.
>>
>> And this change belongs to the AMBA subsystem. Please run :
>>
>> scripts/get_maintainer.pl on your patch and add the necessary people from
>> that list for your patch.
>>
>> As such, I don't think brings any value to be added to the tree.
>> I will leave it for the maintainers to comment.
> 
> Looking at the context in this patch, I see code that is reading at
> least the CID but likely also the PID from the device, duplicating
> the code that is already in the bus layer, and stored in the
> amba_device's periphid and cid members...
> 
The idea here was to capture and report an intermittent Ampere PID/CID
read error at the first read. It's not going to disturb me if this patch
is not considered value added, but it served its' purpose in this case
so I thought it might be useful for others to turn on under debug. I can
resubmit the patch for AMBA, or not.

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Re: [PATCH 2/3] coresight etm4x: Add 32-bit read/write option to split 64-bit words

[Steve Clevenger]

Hi Suzuki,

Comments in-line.

Steve

On 1/20/2023 3:19 AM, Suzuki K Poulose wrote:
> On 20/01/2023 00:51, Steve Clevenger wrote:
>> Add 32-bit read/write access option for Ampere ETMv4.6 64-bit registers.
>> Ampere Computing erratum AC03_DEBUG_10 describes a design decision where
>> 64-bit read/write access is not supported for the ETMv4.6 implementation.
>> These 64-bit registers must be accessed as 2 ea. 32-bit registers.
>> AC03_DEBUG_10 is described in the AmpereOne Developer Errata:
>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
> 
> As with the previous comment, please :
>   a) If this is because of the system instruction access support
>   b) Document the erratum
>
I presume you're referring to your previous comment about adding these
errata to "Documentation/arm64/silicon-errata.rst". Let me see if
there's any heartburn with this internal to Ampere. I don't expect there
to be.

>>
>> Fix drvdata->nr_addr_cmp for() loop range bug to drvdata->nr_addr_cmp * 2
>> in etm_enable_hw.
> 
> Good catch ! Please separate this out and send it as a fix. I can queue
> this.
I'll submit it as a separate patch.

> 
>>
>> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
>> ---
>>   .../coresight/coresight-etm4x-core.c          | 81 ++++++++++++++-----
>>   drivers/hwtracing/coresight/coresight-etm4x.h | 32 ++++++++
>>   2 files changed, 93 insertions(+), 20 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> index 533be1928a09..bf4daa649cdf 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> @@ -452,18 +452,31 @@ static int etm4_enable_hw(struct etmv4_drvdata
>> *drvdata)
>>           if (etm4x_sspcicrn_present(drvdata, i))
>>               etm4x_relaxed_write32(csa, config->ss_pe_cmp[i],
>> TRCSSPCICRn(i));
>>       }
>> -    for (i = 0; i < drvdata->nr_addr_cmp; i++) {
>> -        etm4x_relaxed_write64(csa, config->addr_val[i], TRCACVRn(i));
>> -        etm4x_relaxed_write64(csa, config->addr_acc[i], TRCACATRn(i));
>> +    for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
>> +        if (drvdata->no_quad_mmio) {
>> +            etm4x_split_write64(csa, config->addr_val[i], TRCACVRn(i));
>> +            etm4x_split_write64(csa, config->addr_acc[i], TRCACATRn(i));
>> +        } else {
>> +            etm4x_relaxed_write64(csa, config->addr_val[i],
>> TRCACVRn(i));
>> +            etm4x_relaxed_write64(csa, config->addr_acc[i],
>> TRCACATRn(i));
>> +        }
>> +    }
> 
> Something like this can be leave some places out. I think we could hide
> it under the generic helpers and handle it there. May be "struct
> csdev_access" can cache this "no_quad_mmio" and do the right thing ?
I'm not sure what you're suggesting here. Please be more specific.

> 
> 
>> +    for (i = 0; i < drvdata->numcidc; i++) {
>> +        if (drvdata->no_quad_mmio)
>> +            etm4x_split_write64(csa, config->ctxid_pid[i],
>> TRCCIDCVRn(i));
>> +        else
>> +            etm4x_relaxed_write64(csa, config->ctxid_pid[i],
>> TRCCIDCVRn(i));
>>       }
>> -    for (i = 0; i < drvdata->numcidc; i++)
>> -        etm4x_relaxed_write64(csa, config->ctxid_pid[i], TRCCIDCVRn(i));
>>       etm4x_relaxed_write32(csa, config->ctxid_mask0, TRCCIDCCTLR0);
>>       if (drvdata->numcidc > 4)
>>           etm4x_relaxed_write32(csa, config->ctxid_mask1, TRCCIDCCTLR1);
>>   -    for (i = 0; i < drvdata->numvmidc; i++)
>> -        etm4x_relaxed_write64(csa, config->vmid_val[i], TRCVMIDCVRn(i));
>> +    for (i = 0; i < drvdata->numvmidc; i++) {
>> +        if (drvdata->no_quad_mmio)
>> +            etm4x_split_write64(csa, config->vmid_val[i],
>> TRCVMIDCVRn(i));
>> +        else
>> +            etm4x_relaxed_write64(csa, config->vmid_val[i],
>> TRCVMIDCVRn(i));
>> +    }
>>       etm4x_relaxed_write32(csa, config->vmid_mask0, TRCVMIDCCTLR0);
>>       if (drvdata->numvmidc > 4)
>>           etm4x_relaxed_write32(csa, config->vmid_mask1, TRCVMIDCCTLR1);
>> @@ -1670,8 +1683,13 @@ static int __etm4_cpu_save(struct etmv4_drvdata
>> *drvdata)
>>       }
>>         for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
>> -        state->trcacvr[i] = etm4x_read64(csa, TRCACVRn(i));
>> -        state->trcacatr[i] = etm4x_read64(csa, TRCACATRn(i));
>> +        if (drvdata->no_quad_mmio) {
>> +            state->trcacvr[i] = etm4x_split_read64(csa, TRCACVRn(i));
>> +            state->trcacatr[i] = etm4x_split_read64(csa, TRCACATRn(i));
>> +        } else {
>> +            state->trcacvr[i] = etm4x_read64(csa, TRCACVRn(i));
>> +            state->trcacatr[i] = etm4x_read64(csa, TRCACATRn(i));
>> +        }
>>       }
>>         /*
>> @@ -1681,11 +1699,19 @@ static int __etm4_cpu_save(struct
>> etmv4_drvdata *drvdata)
>>        * unit") of ARM IHI 0064D.
>>        */
>>   -    for (i = 0; i < drvdata->numcidc; i++)
>> -        state->trccidcvr[i] = etm4x_read64(csa, TRCCIDCVRn(i));
>> +    for (i = 0; i < drvdata->numcidc; i++) {
>> +        if (drvdata->no_quad_mmio)
>> +            state->trccidcvr[i] = etm4x_split_read64(csa,
>> TRCCIDCVRn(i));
>> +        else
>> +            state->trccidcvr[i] = etm4x_read64(csa, TRCCIDCVRn(i));
>> +    }
>>   -    for (i = 0; i < drvdata->numvmidc; i++)
>> -        state->trcvmidcvr[i] = etm4x_read64(csa, TRCVMIDCVRn(i));
>> +    for (i = 0; i < drvdata->numvmidc; i++) {
>> +        if (drvdata->no_quad_mmio)
>> +            state->trcvmidcvr[i] = etm4x_split_read64(csa,
>> TRCVMIDCVRn(i));
>> +        else
>> +            state->trcvmidcvr[i] = etm4x_read64(csa, TRCVMIDCVRn(i));
>> +    }
>>         state->trccidcctlr0 = etm4x_read32(csa, TRCCIDCCTLR0);
>>       if (drvdata->numcidc > 4)
>> @@ -1799,15 +1825,28 @@ static void __etm4_cpu_restore(struct
>> etmv4_drvdata *drvdata)
>>       }
>>         for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
>> -        etm4x_relaxed_write64(csa, state->trcacvr[i], TRCACVRn(i));
>> -        etm4x_relaxed_write64(csa, state->trcacatr[i], TRCACATRn(i));
>> +        if (drvdata->no_quad_mmio) {
>> +            etm4x_split_write64(csa, state->trcacvr[i], TRCACVRn(i));
>> +            etm4x_split_write64(csa, state->trcacatr[i], TRCACATRn(i));
>> +        } else {
>> +            etm4x_relaxed_write64(csa, state->trcacvr[i], TRCACVRn(i));
>> +            etm4x_relaxed_write64(csa, state->trcacatr[i],
>> TRCACATRn(i));
>> +        }
>>       }
>>   -    for (i = 0; i < drvdata->numcidc; i++)
>> -        etm4x_relaxed_write64(csa, state->trccidcvr[i], TRCCIDCVRn(i));
>> +    for (i = 0; i < drvdata->numcidc; i++) {
>> +        if (drvdata->no_quad_mmio)
>> +            etm4x_split_write64(csa, state->trccidcvr[i],
>> TRCCIDCVRn(i));
>> +        else
>> +            etm4x_relaxed_write64(csa, state->trccidcvr[i],
>> TRCCIDCVRn(i));
>> +    }
>>   -    for (i = 0; i < drvdata->numvmidc; i++)
>> -        etm4x_relaxed_write64(csa, state->trcvmidcvr[i],
>> TRCVMIDCVRn(i));
>> +    for (i = 0; i < drvdata->numvmidc; i++) {
>> +        if (drvdata->no_quad_mmio)
>> +            etm4x_split_write64(csa, state->trcvmidcvr[i],
>> TRCVMIDCVRn(i));
>> +        else
>> +            etm4x_relaxed_write64(csa, state->trcvmidcvr[i],
>> TRCVMIDCVRn(i));
>> +    }
>>         etm4x_relaxed_write32(csa, state->trccidcctlr0, TRCCIDCCTLR0);
>>       if (drvdata->numcidc > 4)
>> @@ -2047,8 +2086,10 @@ static int etm4_probe(struct device *dev, void
>> __iomem *base, u32 etm_pid)
>>        * isolates the manufacturer JEP106 ID in the PID.
>>        * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>>        */
>> -    if ((init_arg.pid & 0x000FF000) == 0x00096000)
>> +    if ((init_arg.pid & 0x000FF000) == 0x00096000) {
>>           drvdata->mmio_external = true;
>> +        drvdata->no_quad_mmio = true;
>> +    }
>>         /*
>>        * Serialize against CPUHP callbacks to avoid race condition
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h
>> b/drivers/hwtracing/coresight/coresight-etm4x.h
>> index cf4f9f2e1807..0650bcdff410 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
>> @@ -1016,6 +1016,7 @@ struct etmv4_save_state {
>>    *           the trace unit.
>>    * @arch_features: Bitmap of arch features of etmv4 devices.
>>    * @mmio_external: True if ETM considers MMIO an external access.
>> + * @no_quad_mmio:  True if ETM does not support 64-bit (quad) access.
>>    */
>>   struct etmv4_drvdata {
>>       void __iomem            *base;
>> @@ -1069,6 +1070,7 @@ struct etmv4_drvdata {
>>       bool                skip_power_up;
>>       DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
>>       bool                mmio_external;
>> +    bool                no_quad_mmio;
>>   };
>>     /* Address comparator access types */
>> @@ -1093,6 +1095,36 @@ void etm4_config_trace_mode(struct etmv4_config
>> *config);
>>   u64 etm4x_sysreg_read(u32 offset, bool _relaxed, bool _64bit);
>>   void etm4x_sysreg_write(u64 val, u32 offset, bool _relaxed, bool
>> _64bit);
>>   +/* 64-bit aligned to convert 64-bit access to 2 ea. 32-bit access */
>> +#pragma pack(push, 8)
>> +
>> +struct etm_quad_split {
>> +    u32 lsw;
>> +    u32 msw;
>> +};
>> +
>> +#pragma pack(pop)
>> +
>> +static inline u64 etm4x_split_read64(struct csdev_access *csa,
>> unsigned int offset)
>> +{
>> +    struct etm_quad_split container;
>> +
>> +    container.lsw = etm4x_read32(csa, offset);
>> +    container.msw = etm4x_read32(csa, offset + sizeof(u32));
>> +
>> +    return *(u64 *) &container;
> 
> Wouldn't this break with the "endianness" flip ? (Not that we have BE
> implementations). Could we not combine the two values to a 64bit value
> and pass that instead ?
The split implementation writes/reads 32-bit words to/from 2 consecutive
32-bit aligned memory addresses independent of endianness so it doesn't
care. I'm not sure I understand what you're getting at by combining the
2 ea. 32-bit values into a 1 ea. 64-bit value. The etm4x_split_read64
and etm4x_split_write64 calls both use 64-bit values in and out.
Internal to this code, both read and write accesses must use 32-bit values.

> 
> Similarly below.
> 
> Suzuki
> 
>> +}
>> +
>> +static inline void etm4x_split_write64(struct csdev_access *csa, u64
>> quad, unsigned int offset)
>> +{
>> +    struct etm_quad_split container;
>> +
>> +    *(u64 *) &container = quad;
>> +
>> +    etm4x_relaxed_write32(csa, container.lsw, offset);
>> +    etm4x_relaxed_write32(csa, container.msw, offset + sizeof(u32));
>> +}
>> +
>>   static inline bool etm4x_is_ete(struct etmv4_drvdata *drvdata)
>>   {
>>       return drvdata->arch >= ETM_ARCH_ETE;
> 

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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Suzuki K Poulose]

On 21/01/2023 07:30, Steve Clevenger wrote:
> 
> Hi Suzuki,
> 
> Comments in-line. Please note the approach I attempted while adding in
> the Ampere support was to otherwise not disturb existing driver code for
> non-Ampere parts.
> 
> Steve
> 
> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>> Hi Steve
>>
>> Thanks for the patches. Have a few comments below.
>>
>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>> Computing design decision MMIO reads are considered the same as an
>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>> (now deprecated) is supported.
>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>
>> Please could you add this erratum to the :
>>
>> Documentation/arm64/silicon-errata.rst ?
>>
>> Given the ETM is v4.6, doesn't it support system instructions and
>> that is causing this issue of "MMIO access is considered external" ?
>> If it does, I think we should drop all of this and simply wire the
>> system instruction access support.

> That's not the issue in this case. This MMIO access should've been
> allowed by the Ampere ETMv4.6 implementation.  Based on comments I've

That doesn't answe the question. Please could you confirm the value of 
ID_AA64DFR0_EL1 on your system ?

Or, are you able to try this on your ACPI based system and see if you 
are able to use the etm ? (UNTESTED hack !)


diff --git a/drivers/acpi/acpi_amba.c b/drivers/acpi/acpi_amba.c
index f5b443ab01c2..099966cbac5a 100644
--- a/drivers/acpi/acpi_amba.c
+++ b/drivers/acpi/acpi_amba.c
@@ -22,7 +22,6 @@
  static const struct acpi_device_id amba_id_list[] = {
  	{"ARMH0061", 0}, /* PL061 GPIO Device */
  	{"ARMH0330", 0}, /* ARM DMA Controller DMA-330 */
-	{"ARMHC500", 0}, /* ARM CoreSight ETM4x */
  	{"ARMHC501", 0}, /* ARM CoreSight ETR */
  	{"ARMHC502", 0}, /* ARM CoreSight STM */
  	{"ARMHC503", 0}, /* ARM CoreSight Debug */
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c 
b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 1ea8f173cca0..66670533fd54 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -3,6 +3,7 @@
   * Copyright (c) 2014, The Linux Foundation. All rights reserved.
   */

+#include <linux/acpi.h>
  #include <linux/bitops.h>
  #include <linux/kernel.h>
  #include <linux/moduleparam.h>
@@ -2286,12 +2287,22 @@ static const struct of_device_id 
etm4_sysreg_match[] = {
  	{}
  };

+#ifdef CONFIG_ACPI
+static const struct acpi_device_id etm4x_acpi_ids[] = {
+	{"ARMHC500", 0}, /* ARM CoreSight ETM4x */
+	{}
+};
+
+MODULE_DEVICE_TABLE(acpi, etm4x_acpi_ids);
+#endif
+
  static struct platform_driver etm4_platform_driver = {
  	.probe		= etm4_probe_platform_dev,
  	.remove		= etm4_remove_platform_dev,
  	.driver			= {
  		.name			= "coresight-etm4x",
  		.of_match_table		= etm4_sysreg_match,
+		.acpi_match_table = ACPI_PTR(etm4x_acpi_ids),
  		.suppress_bind_attrs	= true,
  	},
  };




> read in the driver code, the MMIO read access to TRCIDR1 occurs after a
> TRCDEVARCH access. The comments suggest this was to accommodate
> potentially unreliable TRCDEVARCH (and TRCIDR1) values. This Ampere
> ETMv4.6 allows an MMIO access to TRCDEVARCH, but not to TRCIDR1 unless
> the TRCOSLAR.OSLK lock is cleared first.
> 
>>
>>>
>>> Add Ampere ETM PID required for Coresight ETM driver support.
>>>
>>> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
>>> ---
>>>    .../coresight/coresight-etm4x-core.c          | 36 +++++++++++++++----
>>>    drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
>>>    2 files changed, 32 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> index 1cc052979e01..533be1928a09 100644
>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
>>>        drvdata = dev_get_drvdata(init_arg->dev);
>>>        csa = init_arg->csa;
>>>    +    /* Detect the support for OS Lock before we actually use it */
>>> +    etm_detect_os_lock(drvdata, csa);
>>> + > +    /*
>>> +     * For ETM implementations that consider MMIO an external access
>>> +     * clear TRCOSLAR.OSLK early.
>>> +     */
>>> +    if (drvdata->mmio_external)
>>> +        etm4_os_unlock_csa(drvdata, csa);
>>> +
>>>        /*
>>>         * If we are unable to detect the access mechanism,
>>>         * or unable to detect the trace unit type, fail
>>> -     * early.
>>> +     * early. Reset TRCOSLAR.OSLK if cleared.
>>>         */
>>> -    if (!etm4_init_csdev_access(drvdata, csa))
>>> +    if (!etm4_init_csdev_access(drvdata, csa)) {
>>> +        if (drvdata->mmio_external)
>>> +            etm4_os_lock(drvdata);
>>
>> Couldn't this unlock/lock sequence be moved into the
>> etm4_init_csdev_iomem_access() where it actually matters ?
>>
>> Or thinking more about it, we could actually move the unlock step early
>> for all ETMs irrespective of whether they are affected by this erratum.
>> Of course, putting this back, if we fail to detect the ETM properly.
>> I don't see any issue with that.


> I agree the lock could be cleared earlier in the code. That's what this
> patch does for Ampere. If it's decided ok to do for other (or all)
> manufacturers, then the Ampere specific ID check goes away in this
> place. The Ampere ID check (and flag) to determine whether the [Patch
> 2/3] 64-bit access is split into 2 ea. 32-bit accesses would remain, or
> use an existing feature mask as suggested by Mike Leach in a later review.
> 
>>
>>>            return;
>>> +    }
>>>    -    /* Detect the support for OS Lock before we actually use it */
>>> -    etm_detect_os_lock(drvdata, csa);
>>> +    /*
>>> +     * Make sure all registers are accessible
>>> +     * TRCOSLAR.OSLK may already be clear
>>> +     */
>>> +    if (!drvdata->mmio_external)
>>> +        etm4_os_unlock_csa(drvdata, csa);
>>>    -    /* Make sure all registers are accessible */
>>> -    etm4_os_unlock_csa(drvdata, csa);
>>>        etm4_cs_unlock(drvdata, csa);
>>>          etm4_check_arch_features(drvdata, init_arg->pid);
>>> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void
>>> __iomem *base, u32 etm_pid)
>>>        init_arg.csa = &access;
>>>        init_arg.pid = etm_pid;
>>>    +    /*
>>> +     * Ampere ETM v4.6 considers MMIO access as external. This mask
>>> +     * isolates the manufacturer JEP106 ID in the PID.
>>> +     * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>>> +     */
>>
>> Does it affect all Ampere ETMs ? You seem to be ignoring the
>> PDIR1.PART_1, PDIR0_PART_0 fields, which happens to be 0.

> This is the first Ampere ETMv4.x implementation. I wrote the ID check
> like this specifically because Ampere does not intend to address this
> for ETM designs in progress.

I would recommend to make this mask stricter and apply this to the 
current implementation. When there are more, we could add this here, 
rather than having to leave this work around for all the possible cores.

> 
>>
>>> +    if ((init_arg.pid & 0x000FF000) == 0x00096000)
>>> +        drvdata->mmio_external = true;
>> Like I said, we may be able to get rid of this flag and do the step for
>> all ETMs. But before all of that, I would like to see if this is problem
>> because we are skipping the system instruction route.
>>

> We understand MMIO access is deprecated going forward. There is other
> Linux code to be concerned about. For example, AMBA code reads the
> component PID/CID. This discovery code uses mapped values digested from
> the CoreSight ACPI which are the descriptions and graphs for the

With the "proposed" ACPI support for system register, AMBA would not be
involved at all.

> manufacturer trace implementation. There may be other Linux code I'm not
> aware. Note the ASL examples in ARM Document number: DEN0067 specify
> MMIO locations for every CoreSight component.

Yes, but this was never updated to cover the system register based 
implementations. I will chase this up.


Suzuki


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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Mike Leach]

Hi Steve,

On Sat, 21 Jan 2023 at 07:31, Steve Clevenger
<scclevenger@os.amperecomputing.com> wrote:
>
>
> Hi Mike,
>
> Comments in-line.
>
> Steve
>
> On 1/20/2023 3:45 AM, Mike Leach wrote:
> > Hi Steve,
> >
> > On Fri, 20 Jan 2023 at 00:52, Steve Clevenger
> > <scclevenger@os.amperecomputing.com> wrote:
> >>
> >> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
> >> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
> >> Computing design decision MMIO reads are considered the same as an
> >> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
> >> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
> >> is valid regardless of TRCOSLAR.OSLK provided MMIO access
> >> (now deprecated) is supported.
> >> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
> >> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
> >>
> >> Add Ampere ETM PID required for Coresight ETM driver support.
> >>
> >> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
> >> ---
> >>  .../coresight/coresight-etm4x-core.c          | 36 +++++++++++++++----
> >>  drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
> >>  2 files changed, 32 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> >> index 1cc052979e01..533be1928a09 100644
> >> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> >> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> >> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
> >>         drvdata = dev_get_drvdata(init_arg->dev);
> >>         csa = init_arg->csa;
> >>
> >
> > As far as I can tell there appears to be an initialisation issue here.
> > etm_probe()
> > ...
> > struct csdev_access access = { 0 };
> > ...
> > init_arg.csa = &access
> >
> > ::call=> etm4_init_arch_data(init_arg)
> >
> > Thus csa is uninitialised?
> It looks to me csa is intended to be initialized to zero? In any case,
> the Ampere check uses only the ETM pid, which is initialized directly above.
>

Sorry, I should have been more explicit.

csa is the addressing abstraction used by all the underlying register
read/write code.

It is initialised to {0} in the calling code, probably to avoid the
kernel tests complaining about uninitialised use of a variable.

However in the etm4_init_csdev_access() function we are using a base
address then it is initialised to:-

struct csdev_access {
    io_mem = true;
    *base = io_mem_base_addr;
};

and in the access using system registers for an etm4 to:

struct csdev_access {
    io_mem = false;
    *read = etm4x_sysreg_read()
    *write = etm4x_sysreg_write()
};

Thus all underlying register access can use the correct method for the device.

> >
> >> +       /* Detect the support for OS Lock before we actually use it */
> >> +       etm_detect_os_lock(drvdata, csa);
> >> +

Thus passing a 0 init csa object to the etm_detect_os_lock()  fn above
seems to be suspicious.

> >> +       /*
> >> +        * For ETM implementations that consider MMIO an external access
> >> +        * clear TRCOSLAR.OSLK early.
> >> +        */
> >> +       if (drvdata->mmio_external)
> >> +               etm4_os_unlock_csa(drvdata, csa);
> >> +
> >>         /*
> >>          * If we are unable to detect the access mechanism,
> >>          * or unable to detect the trace unit type, fail
> >> -        * early.
> >> +        * early. Reset TRCOSLAR.OSLK if cleared.
> >>          */
> >> -       if (!etm4_init_csdev_access(drvdata, csa))
> >> +       if (!etm4_init_csdev_access(drvdata, csa)) {
> >
> > This call initialises csa according to sysreg / iomem access requirements

> csa is initialized only when no drvdata->base exists.

Not so - csa is initialised in both circumstances as described above.

> Under what
> circumstance would there be no ETM base given the recommended CoreSight
> ACPI implementation? See the examples in ARM Document number: DEN0067.


This will be used in the ETE devices (which share the etm4 driver), or
any ETM4.6+ that uses the "arm,coresight-etm4x-sysreg" device tree
binding (not sure what the ACPI equivalent is).

So, either way, you need an init csa, before passing it to the driver calls.

Later in the initialisation sequence we generate a coresight_device
object which the csa is bound to, and finally if all is well the
coresight_device is bound to drvdata at which point the device is
ready for use.

It is unfortunate, but to handle the two methods of register access,
the initilialisation process for the driver has become more
complicated with ordering dependencies - to ensure that the rest of
the driver remains simpler when accessing device registers.

As Suzuki mentioned - moving this specific lock requirement into the
_init function would be clearer and ensure that the initialisation
sequences were observed.

Regards

Mike

> >
> >
> >
> >> +               if (drvdata->mmio_external)
> >> +                       etm4_os_lock(drvdata);
> >>                 return;
> >> +       }
> >>
> >> -       /* Detect the support for OS Lock before we actually use it */
> >> -       etm_detect_os_lock(drvdata, csa);
> >> +       /*
> >> +        * Make sure all registers are accessible
> >> +        * TRCOSLAR.OSLK may already be clear
> >> +        */
> >> +       if (!drvdata->mmio_external)
> >> +               etm4_os_unlock_csa(drvdata, csa);
> >>
> >> -       /* Make sure all registers are accessible */
> >> -       etm4_os_unlock_csa(drvdata, csa);
> >>         etm4_cs_unlock(drvdata, csa);
> >>
> >>         etm4_check_arch_features(drvdata, init_arg->pid);
> >> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
> >>         init_arg.csa = &access;
> >>         init_arg.pid = etm_pid;
> >>
> >> +       /*
> >> +        * Ampere ETM v4.6 considers MMIO access as external. This mask
> >> +        * isolates the manufacturer JEP106 ID in the PID.
> >> +        * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
> >> +        */
> >> +       if ((init_arg.pid & 0x000FF000) == 0x00096000)
> >> +               drvdata->mmio_external = true;
> >> +
> >>         /*
> >>          * Serialize against CPUHP callbacks to avoid race condition
> >>          * between the smp call and saving the delayed probe.
> >> @@ -2192,6 +2215,7 @@ static const struct amba_id etm4_ids[] = {
> >>         CS_AMBA_ID(0x000bb95e),                 /* Cortex-A57 */
> >>         CS_AMBA_ID(0x000bb95a),                 /* Cortex-A72 */
> >>         CS_AMBA_ID(0x000bb959),                 /* Cortex-A73 */
> >> +       CS_AMBA_UCI_ID(0x00096000, uci_id_etm4),/* Ampere ARMv8 */
> >>         CS_AMBA_UCI_ID(0x000bb9da, uci_id_etm4),/* Cortex-A35 */
> >>         CS_AMBA_UCI_ID(0x000bbd05, uci_id_etm4),/* Cortex-A55 */
> >>         CS_AMBA_UCI_ID(0x000bbd0a, uci_id_etm4),/* Cortex-A75 */
> >> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> >> index 4b21bb79f168..cf4f9f2e1807 100644
> >> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> >> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> >> @@ -1015,6 +1015,7 @@ struct etmv4_save_state {
> >>   * @skip_power_up: Indicates if an implementation can skip powering up
> >>   *                the trace unit.
> >>   * @arch_features: Bitmap of arch features of etmv4 devices.
> >> + * @mmio_external: True if ETM considers MMIO an external access.
> >>   */
> >>  struct etmv4_drvdata {
> >>         void __iomem                    *base;
> >> @@ -1067,6 +1068,7 @@ struct etmv4_drvdata {
> >>         bool                            state_needs_restore;
> >>         bool                            skip_power_up;
> >>         DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
> >
> > Rather than continue to add bools - is it not worthwhile adding to the
> > bitmap above and extending the arch features API to allow a
> > "has_feature" call?
> I can look into this. I agree using a bool for every exception doesn't
> scale well. Referring to one Suzuki Poulose review comment, his proposal
> to clear TRCOSLAR.OSLK early for all parts would mean one of these bools
> could go away. Otherwise, possibly add one (or more) bit definitions for
> use by the etm4_disable_arch_specific call. The order of this call would
> need to change, depending.
>
> >
> >> +       bool                            mmio_external;
> >>  };
> >>
> >>  /* Address comparator access types */
> >> --
> >> 2.25.1
> >>
> > Regards
> >
> > Mike



-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK

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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Steve Clevenger]

On 1/23/2023 2:54 AM, Suzuki K Poulose wrote:
> On 21/01/2023 07:30, Steve Clevenger wrote:
>>
>> Hi Suzuki,
>>
>> Comments in-line. Please note the approach I attempted while adding in
>> the Ampere support was to otherwise not disturb existing driver code for
>> non-Ampere parts.
>>
>> Steve
>>
>> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>>> Hi Steve
>>>
>>> Thanks for the patches. Have a few comments below.
>>>
>>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>> Computing design decision MMIO reads are considered the same as an
>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>> (now deprecated) is supported.
>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>
>>> Please could you add this erratum to the :
>>>
>>> Documentation/arm64/silicon-errata.rst ?
>>>
>>> Given the ETM is v4.6, doesn't it support system instructions and
>>> that is causing this issue of "MMIO access is considered external" ?
>>> If it does, I think we should drop all of this and simply wire the
>>> system instruction access support.
> 
>> That's not the issue in this case. This MMIO access should've been
>> allowed by the Ampere ETMv4.6 implementation.  Based on comments I've
> 
> That doesn't answe the question. Please could you confirm the value of
> ID_AA64DFR0_EL1 on your system ?
This ID_AA64DFR0_EL1 value came from a TRACE32 debug session connected
to this part. The ID_AA64DFR0_EL1 value is 0x000F01F210307619. So,
TraceVer, bits [7:4] are b0001. My understanding is the system register
interface must be implemented on all ETMv4.6 parts.

> 
> Or, are you able to try this on your ACPI based system and see if you
> are able to use the etm ? (UNTESTED hack !)
> 
> 
> diff --git a/drivers/acpi/acpi_amba.c b/drivers/acpi/acpi_amba.c
> index f5b443ab01c2..099966cbac5a 100644
> --- a/drivers/acpi/acpi_amba.c
> +++ b/drivers/acpi/acpi_amba.c
> @@ -22,7 +22,6 @@
>  static const struct acpi_device_id amba_id_list[] = {
>      {"ARMH0061", 0}, /* PL061 GPIO Device */
>      {"ARMH0330", 0}, /* ARM DMA Controller DMA-330 */
> -    {"ARMHC500", 0}, /* ARM CoreSight ETM4x */
>      {"ARMHC501", 0}, /* ARM CoreSight ETR */
>      {"ARMHC502", 0}, /* ARM CoreSight STM */
>      {"ARMHC503", 0}, /* ARM CoreSight Debug */
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 1ea8f173cca0..66670533fd54 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -3,6 +3,7 @@
>   * Copyright (c) 2014, The Linux Foundation. All rights reserved.
>   */
> 
> +#include <linux/acpi.h>
>  #include <linux/bitops.h>
>  #include <linux/kernel.h>
>  #include <linux/moduleparam.h>
> @@ -2286,12 +2287,22 @@ static const struct of_device_id
> etm4_sysreg_match[] = {
>      {}
>  };
> 
> +#ifdef CONFIG_ACPI
> +static const struct acpi_device_id etm4x_acpi_ids[] = {
> +    {"ARMHC500", 0}, /* ARM CoreSight ETM4x */
> +    {}
> +};
> +
> +MODULE_DEVICE_TABLE(acpi, etm4x_acpi_ids);
> +#endif
> +
>  static struct platform_driver etm4_platform_driver = {
>      .probe        = etm4_probe_platform_dev,
>      .remove        = etm4_remove_platform_dev,
>      .driver            = {
>          .name            = "coresight-etm4x",
>          .of_match_table        = etm4_sysreg_match,
> +        .acpi_match_table = ACPI_PTR(etm4x_acpi_ids),
>          .suppress_bind_attrs    = true,
>      },
>  };
> 
> 
> 
> 
>> read in the driver code, the MMIO read access to TRCIDR1 occurs after a
>> TRCDEVARCH access. The comments suggest this was to accommodate
>> potentially unreliable TRCDEVARCH (and TRCIDR1) values. This Ampere
>> ETMv4.6 allows an MMIO access to TRCDEVARCH, but not to TRCIDR1 unless
>> the TRCOSLAR.OSLK lock is cleared first.
>>
>>>
>>>>
>>>> Add Ampere ETM PID required for Coresight ETM driver support.
>>>>
>>>> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
>>>> ---
>>>>    .../coresight/coresight-etm4x-core.c          | 36
>>>> +++++++++++++++----
>>>>    drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
>>>>    2 files changed, 32 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>> index 1cc052979e01..533be1928a09 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
>>>>        drvdata = dev_get_drvdata(init_arg->dev);
>>>>        csa = init_arg->csa;
>>>>    +    /* Detect the support for OS Lock before we actually use it */
>>>> +    etm_detect_os_lock(drvdata, csa);
>>>> + > +    /*
>>>> +     * For ETM implementations that consider MMIO an external access
>>>> +     * clear TRCOSLAR.OSLK early.
>>>> +     */
>>>> +    if (drvdata->mmio_external)
>>>> +        etm4_os_unlock_csa(drvdata, csa);
>>>> +
>>>>        /*
>>>>         * If we are unable to detect the access mechanism,
>>>>         * or unable to detect the trace unit type, fail
>>>> -     * early.
>>>> +     * early. Reset TRCOSLAR.OSLK if cleared.
>>>>         */
>>>> -    if (!etm4_init_csdev_access(drvdata, csa))
>>>> +    if (!etm4_init_csdev_access(drvdata, csa)) {
>>>> +        if (drvdata->mmio_external)
>>>> +            etm4_os_lock(drvdata);
>>>
>>> Couldn't this unlock/lock sequence be moved into the
>>> etm4_init_csdev_iomem_access() where it actually matters ?
>>>
>>> Or thinking more about it, we could actually move the unlock step early
>>> for all ETMs irrespective of whether they are affected by this erratum.
>>> Of course, putting this back, if we fail to detect the ETM properly.
>>> I don't see any issue with that.
> 
> 
>> I agree the lock could be cleared earlier in the code. That's what this
>> patch does for Ampere. If it's decided ok to do for other (or all)
>> manufacturers, then the Ampere specific ID check goes away in this
>> place. The Ampere ID check (and flag) to determine whether the [Patch
>> 2/3] 64-bit access is split into 2 ea. 32-bit accesses would remain, or
>> use an existing feature mask as suggested by Mike Leach in a later
>> review.
>>
>>>
>>>>            return;
>>>> +    }
>>>>    -    /* Detect the support for OS Lock before we actually use it */
>>>> -    etm_detect_os_lock(drvdata, csa);
>>>> +    /*
>>>> +     * Make sure all registers are accessible
>>>> +     * TRCOSLAR.OSLK may already be clear
>>>> +     */
>>>> +    if (!drvdata->mmio_external)
>>>> +        etm4_os_unlock_csa(drvdata, csa);
>>>>    -    /* Make sure all registers are accessible */
>>>> -    etm4_os_unlock_csa(drvdata, csa);
>>>>        etm4_cs_unlock(drvdata, csa);
>>>>          etm4_check_arch_features(drvdata, init_arg->pid);
>>>> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void
>>>> __iomem *base, u32 etm_pid)
>>>>        init_arg.csa = &access;
>>>>        init_arg.pid = etm_pid;
>>>>    +    /*
>>>> +     * Ampere ETM v4.6 considers MMIO access as external. This mask
>>>> +     * isolates the manufacturer JEP106 ID in the PID.
>>>> +     * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>>>> +     */
>>>
>>> Does it affect all Ampere ETMs ? You seem to be ignoring the
>>> PDIR1.PART_1, PDIR0_PART_0 fields, which happens to be 0.
> 
>> This is the first Ampere ETMv4.x implementation. I wrote the ID check
>> like this specifically because Ampere does not intend to address this
>> for ETM designs in progress.
> 
> I would recommend to make this mask stricter and apply this to the
> current implementation. When there are more, we could add this here,
> rather than having to leave this work around for all the possible cores.
> 
>>
>>>
>>>> +    if ((init_arg.pid & 0x000FF000) == 0x00096000)
>>>> +        drvdata->mmio_external = true;
>>> Like I said, we may be able to get rid of this flag and do the step for
>>> all ETMs. But before all of that, I would like to see if this is problem
>>> because we are skipping the system instruction route.
>>>
> 
>> We understand MMIO access is deprecated going forward. There is other
>> Linux code to be concerned about. For example, AMBA code reads the
>> component PID/CID. This discovery code uses mapped values digested from
>> the CoreSight ACPI which are the descriptions and graphs for the
> 
> With the "proposed" ACPI support for system register, AMBA would not be
> involved at all.
> 
>> manufacturer trace implementation. There may be other Linux code I'm not
>> aware. Note the ASL examples in ARM Document number: DEN0067 specify
>> MMIO locations for every CoreSight component.
> 
> Yes, but this was never updated to cover the system register based
> implementations. I will chase this up.
> 
> 
> Suzuki
> 

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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Suzuki K Poulose]

On 23/01/2023 17:22, Steve Clevenger wrote:
> 
> 
> On 1/23/2023 2:54 AM, Suzuki K Poulose wrote:
>> On 21/01/2023 07:30, Steve Clevenger wrote:
>>>
>>> Hi Suzuki,
>>>
>>> Comments in-line. Please note the approach I attempted while adding in
>>> the Ampere support was to otherwise not disturb existing driver code for
>>> non-Ampere parts.
>>>
>>> Steve
>>>
>>> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>>>> Hi Steve
>>>>
>>>> Thanks for the patches. Have a few comments below.
>>>>
>>>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
>>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>>> Computing design decision MMIO reads are considered the same as an
>>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>>> (now deprecated) is supported.
>>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>
>>>> Please could you add this erratum to the :
>>>>
>>>> Documentation/arm64/silicon-errata.rst ?
>>>>
>>>> Given the ETM is v4.6, doesn't it support system instructions and
>>>> that is causing this issue of "MMIO access is considered external" ?
>>>> If it does, I think we should drop all of this and simply wire the
>>>> system instruction access support.
>>
>>> That's not the issue in this case. This MMIO access should've been
>>> allowed by the Ampere ETMv4.6 implementation.  Based on comments I've
>>
>> That doesn't answe the question. Please could you confirm the value of
>> ID_AA64DFR0_EL1 on your system ?
> This ID_AA64DFR0_EL1 value came from a TRACE32 debug session connected
> to this part. The ID_AA64DFR0_EL1 value is 0x000F01F210307619. So,
> TraceVer, bits [7:4] are b0001. My understanding is the system register
> interface must be implemented on all ETMv4.6 parts.

So, I don't understand why we are pushing towards enabling the 
"obsolete" MMIO interface ? Is this because "ACPI" mandates it ?
Then, please don't. The spec needs an update to reflect the ETMs
with sysreg access and ETEs.

Why not stick to the system register access* ?

* PS: The ACPI support for the ETM/ETE needs additional changes to the
CoreSight driver, *not* the CoreSight ACPI spec. @Anshuman is working on 
this at the moment and will be available soon.

The hack patch below should be sufficient to give it a try and if it works.

Kind regards
Suzuki

> 
>>
>> Or, are you able to try this on your ACPI based system and see if you
>> are able to use the etm ? (UNTESTED hack !)
>>
>>
>> diff --git a/drivers/acpi/acpi_amba.c b/drivers/acpi/acpi_amba.c
>> index f5b443ab01c2..099966cbac5a 100644
>> --- a/drivers/acpi/acpi_amba.c
>> +++ b/drivers/acpi/acpi_amba.c
>> @@ -22,7 +22,6 @@
>>   static const struct acpi_device_id amba_id_list[] = {
>>       {"ARMH0061", 0}, /* PL061 GPIO Device */
>>       {"ARMH0330", 0}, /* ARM DMA Controller DMA-330 */
>> -    {"ARMHC500", 0}, /* ARM CoreSight ETM4x */
>>       {"ARMHC501", 0}, /* ARM CoreSight ETR */
>>       {"ARMHC502", 0}, /* ARM CoreSight STM */
>>       {"ARMHC503", 0}, /* ARM CoreSight Debug */
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> index 1ea8f173cca0..66670533fd54 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> @@ -3,6 +3,7 @@
>>    * Copyright (c) 2014, The Linux Foundation. All rights reserved.
>>    */
>>
>> +#include <linux/acpi.h>
>>   #include <linux/bitops.h>
>>   #include <linux/kernel.h>
>>   #include <linux/moduleparam.h>
>> @@ -2286,12 +2287,22 @@ static const struct of_device_id
>> etm4_sysreg_match[] = {
>>       {}
>>   };
>>
>> +#ifdef CONFIG_ACPI
>> +static const struct acpi_device_id etm4x_acpi_ids[] = {
>> +    {"ARMHC500", 0}, /* ARM CoreSight ETM4x */
>> +    {}
>> +};
>> +
>> +MODULE_DEVICE_TABLE(acpi, etm4x_acpi_ids);
>> +#endif
>> +
>>   static struct platform_driver etm4_platform_driver = {
>>       .probe        = etm4_probe_platform_dev,
>>       .remove        = etm4_remove_platform_dev,
>>       .driver            = {
>>           .name            = "coresight-etm4x",
>>           .of_match_table        = etm4_sysreg_match,
>> +        .acpi_match_table = ACPI_PTR(etm4x_acpi_ids),
>>           .suppress_bind_attrs    = true,
>>       },
>>   };
>>
>>
>>
>>
>>> read in the driver code, the MMIO read access to TRCIDR1 occurs after a
>>> TRCDEVARCH access. The comments suggest this was to accommodate
>>> potentially unreliable TRCDEVARCH (and TRCIDR1) values. This Ampere
>>> ETMv4.6 allows an MMIO access to TRCDEVARCH, but not to TRCIDR1 unless
>>> the TRCOSLAR.OSLK lock is cleared first.
>>>
>>>>
>>>>>
>>>>> Add Ampere ETM PID required for Coresight ETM driver support.
>>>>>
>>>>> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
>>>>> ---
>>>>>     .../coresight/coresight-etm4x-core.c          | 36
>>>>> +++++++++++++++----
>>>>>     drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
>>>>>     2 files changed, 32 insertions(+), 6 deletions(-)
>>>>>
>>>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>> index 1cc052979e01..533be1928a09 100644
>>>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
>>>>>         drvdata = dev_get_drvdata(init_arg->dev);
>>>>>         csa = init_arg->csa;
>>>>>     +    /* Detect the support for OS Lock before we actually use it */
>>>>> +    etm_detect_os_lock(drvdata, csa);
>>>>> + > +    /*
>>>>> +     * For ETM implementations that consider MMIO an external access
>>>>> +     * clear TRCOSLAR.OSLK early.
>>>>> +     */
>>>>> +    if (drvdata->mmio_external)
>>>>> +        etm4_os_unlock_csa(drvdata, csa);
>>>>> +
>>>>>         /*
>>>>>          * If we are unable to detect the access mechanism,
>>>>>          * or unable to detect the trace unit type, fail
>>>>> -     * early.
>>>>> +     * early. Reset TRCOSLAR.OSLK if cleared.
>>>>>          */
>>>>> -    if (!etm4_init_csdev_access(drvdata, csa))
>>>>> +    if (!etm4_init_csdev_access(drvdata, csa)) {
>>>>> +        if (drvdata->mmio_external)
>>>>> +            etm4_os_lock(drvdata);
>>>>
>>>> Couldn't this unlock/lock sequence be moved into the
>>>> etm4_init_csdev_iomem_access() where it actually matters ?
>>>>
>>>> Or thinking more about it, we could actually move the unlock step early
>>>> for all ETMs irrespective of whether they are affected by this erratum.
>>>> Of course, putting this back, if we fail to detect the ETM properly.
>>>> I don't see any issue with that.
>>
>>
>>> I agree the lock could be cleared earlier in the code. That's what this
>>> patch does for Ampere. If it's decided ok to do for other (or all)
>>> manufacturers, then the Ampere specific ID check goes away in this
>>> place. The Ampere ID check (and flag) to determine whether the [Patch
>>> 2/3] 64-bit access is split into 2 ea. 32-bit accesses would remain, or
>>> use an existing feature mask as suggested by Mike Leach in a later
>>> review.
>>>
>>>>
>>>>>             return;
>>>>> +    }
>>>>>     -    /* Detect the support for OS Lock before we actually use it */
>>>>> -    etm_detect_os_lock(drvdata, csa);
>>>>> +    /*
>>>>> +     * Make sure all registers are accessible
>>>>> +     * TRCOSLAR.OSLK may already be clear
>>>>> +     */
>>>>> +    if (!drvdata->mmio_external)
>>>>> +        etm4_os_unlock_csa(drvdata, csa);
>>>>>     -    /* Make sure all registers are accessible */
>>>>> -    etm4_os_unlock_csa(drvdata, csa);
>>>>>         etm4_cs_unlock(drvdata, csa);
>>>>>           etm4_check_arch_features(drvdata, init_arg->pid);
>>>>> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void
>>>>> __iomem *base, u32 etm_pid)
>>>>>         init_arg.csa = &access;
>>>>>         init_arg.pid = etm_pid;
>>>>>     +    /*
>>>>> +     * Ampere ETM v4.6 considers MMIO access as external. This mask
>>>>> +     * isolates the manufacturer JEP106 ID in the PID.
>>>>> +     * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>>>>> +     */
>>>>
>>>> Does it affect all Ampere ETMs ? You seem to be ignoring the
>>>> PDIR1.PART_1, PDIR0_PART_0 fields, which happens to be 0.
>>
>>> This is the first Ampere ETMv4.x implementation. I wrote the ID check
>>> like this specifically because Ampere does not intend to address this
>>> for ETM designs in progress.
>>
>> I would recommend to make this mask stricter and apply this to the
>> current implementation. When there are more, we could add this here,
>> rather than having to leave this work around for all the possible cores.
>>
>>>
>>>>
>>>>> +    if ((init_arg.pid & 0x000FF000) == 0x00096000)
>>>>> +        drvdata->mmio_external = true;
>>>> Like I said, we may be able to get rid of this flag and do the step for
>>>> all ETMs. But before all of that, I would like to see if this is problem
>>>> because we are skipping the system instruction route.
>>>>
>>
>>> We understand MMIO access is deprecated going forward. There is other
>>> Linux code to be concerned about. For example, AMBA code reads the
>>> component PID/CID. This discovery code uses mapped values digested from
>>> the CoreSight ACPI which are the descriptions and graphs for the
>>
>> With the "proposed" ACPI support for system register, AMBA would not be
>> involved at all.
>>
>>> manufacturer trace implementation. There may be other Linux code I'm not
>>> aware. Note the ASL examples in ARM Document number: DEN0067 specify
>>> MMIO locations for every CoreSight component.
>>
>> Yes, but this was never updated to cover the system register based
>> implementations. I will chase this up.
>>
>>
>> Suzuki
>>


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Re: [PATCH 2/3] coresight etm4x: Add 32-bit read/write option to split 64-bit words

[Suzuki K Poulose]

On 22/01/2023 08:32, Steve Clevenger wrote:
> 
> Hi Suzuki,
> 
> Comments in-line.
> 
> Steve
> 
> On 1/20/2023 3:19 AM, Suzuki K Poulose wrote:
>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>> Add 32-bit read/write access option for Ampere ETMv4.6 64-bit registers.
>>> Ampere Computing erratum AC03_DEBUG_10 describes a design decision where
>>> 64-bit read/write access is not supported for the ETMv4.6 implementation.
>>> These 64-bit registers must be accessed as 2 ea. 32-bit registers.
>>> AC03_DEBUG_10 is described in the AmpereOne Developer Errata:
>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>
>> As with the previous comment, please :
>>    a) If this is because of the system instruction access support
>>    b) Document the erratum
>>
> I presume you're referring to your previous comment about adding these
> errata to "Documentation/arm64/silicon-errata.rst". Let me see if
> there's any heartburn with this internal to Ampere. I don't expect there
> to be.
> 
>>>
>>> Fix drvdata->nr_addr_cmp for() loop range bug to drvdata->nr_addr_cmp * 2
>>> in etm_enable_hw.
>>
>> Good catch ! Please separate this out and send it as a fix. I can queue
>> this.
> I'll submit it as a separate patch.
> 
>>
>>>
>>> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
>>> ---
>>>    .../coresight/coresight-etm4x-core.c          | 81 ++++++++++++++-----
>>>    drivers/hwtracing/coresight/coresight-etm4x.h | 32 ++++++++
>>>    2 files changed, 93 insertions(+), 20 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> index 533be1928a09..bf4daa649cdf 100644
>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> @@ -452,18 +452,31 @@ static int etm4_enable_hw(struct etmv4_drvdata
>>> *drvdata)
>>>            if (etm4x_sspcicrn_present(drvdata, i))
>>>                etm4x_relaxed_write32(csa, config->ss_pe_cmp[i],
>>> TRCSSPCICRn(i));
>>>        }
>>> -    for (i = 0; i < drvdata->nr_addr_cmp; i++) {
>>> -        etm4x_relaxed_write64(csa, config->addr_val[i], TRCACVRn(i));
>>> -        etm4x_relaxed_write64(csa, config->addr_acc[i], TRCACATRn(i));
>>> +    for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
>>> +        if (drvdata->no_quad_mmio) {
>>> +            etm4x_split_write64(csa, config->addr_val[i], TRCACVRn(i));
>>> +            etm4x_split_write64(csa, config->addr_acc[i], TRCACATRn(i));
>>> +        } else {
>>> +            etm4x_relaxed_write64(csa, config->addr_val[i],
>>> TRCACVRn(i));
>>> +            etm4x_relaxed_write64(csa, config->addr_acc[i],
>>> TRCACATRn(i));
>>> +        }
>>> +    }
>>
>> Something like this can be leave some places out. I think we could hide
>> it under the generic helpers and handle it there. May be "struct
>> csdev_access" can cache this "no_quad_mmio" and do the right thing ?
> I'm not sure what you're suggesting here. Please be more specific.
> 

e.g.,

struct csdev_access {

	bool no_64bit_access;
}


And use the csdev_*_ operations could :

  if (csa->no_64bit_access) {
	split access
  } else {

  }

i.e., move the tracking of no_quad_mmio to "csa" from "drvdata"

Suzuki

>>
>>
>>> +    for (i = 0; i < drvdata->numcidc; i++) {
>>> +        if (drvdata->no_quad_mmio)
>>> +            etm4x_split_write64(csa, config->ctxid_pid[i],
>>> TRCCIDCVRn(i));
>>> +        else
>>> +            etm4x_relaxed_write64(csa, config->ctxid_pid[i],
>>> TRCCIDCVRn(i));
>>>        }
>>> -    for (i = 0; i < drvdata->numcidc; i++)
>>> -        etm4x_relaxed_write64(csa, config->ctxid_pid[i], TRCCIDCVRn(i));
>>>        etm4x_relaxed_write32(csa, config->ctxid_mask0, TRCCIDCCTLR0);
>>>        if (drvdata->numcidc > 4)
>>>            etm4x_relaxed_write32(csa, config->ctxid_mask1, TRCCIDCCTLR1);
>>>    -    for (i = 0; i < drvdata->numvmidc; i++)
>>> -        etm4x_relaxed_write64(csa, config->vmid_val[i], TRCVMIDCVRn(i));
>>> +    for (i = 0; i < drvdata->numvmidc; i++) {
>>> +        if (drvdata->no_quad_mmio)
>>> +            etm4x_split_write64(csa, config->vmid_val[i],
>>> TRCVMIDCVRn(i));
>>> +        else
>>> +            etm4x_relaxed_write64(csa, config->vmid_val[i],
>>> TRCVMIDCVRn(i));
>>> +    }
>>>        etm4x_relaxed_write32(csa, config->vmid_mask0, TRCVMIDCCTLR0);
>>>        if (drvdata->numvmidc > 4)
>>>            etm4x_relaxed_write32(csa, config->vmid_mask1, TRCVMIDCCTLR1);
>>> @@ -1670,8 +1683,13 @@ static int __etm4_cpu_save(struct etmv4_drvdata
>>> *drvdata)
>>>        }
>>>          for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
>>> -        state->trcacvr[i] = etm4x_read64(csa, TRCACVRn(i));
>>> -        state->trcacatr[i] = etm4x_read64(csa, TRCACATRn(i));
>>> +        if (drvdata->no_quad_mmio) {
>>> +            state->trcacvr[i] = etm4x_split_read64(csa, TRCACVRn(i));
>>> +            state->trcacatr[i] = etm4x_split_read64(csa, TRCACATRn(i));
>>> +        } else {
>>> +            state->trcacvr[i] = etm4x_read64(csa, TRCACVRn(i));
>>> +            state->trcacatr[i] = etm4x_read64(csa, TRCACATRn(i));
>>> +        }
>>>        }
>>>          /*
>>> @@ -1681,11 +1699,19 @@ static int __etm4_cpu_save(struct
>>> etmv4_drvdata *drvdata)
>>>         * unit") of ARM IHI 0064D.
>>>         */
>>>    -    for (i = 0; i < drvdata->numcidc; i++)
>>> -        state->trccidcvr[i] = etm4x_read64(csa, TRCCIDCVRn(i));
>>> +    for (i = 0; i < drvdata->numcidc; i++) {
>>> +        if (drvdata->no_quad_mmio)
>>> +            state->trccidcvr[i] = etm4x_split_read64(csa,
>>> TRCCIDCVRn(i));
>>> +        else
>>> +            state->trccidcvr[i] = etm4x_read64(csa, TRCCIDCVRn(i));
>>> +    }
>>>    -    for (i = 0; i < drvdata->numvmidc; i++)
>>> -        state->trcvmidcvr[i] = etm4x_read64(csa, TRCVMIDCVRn(i));
>>> +    for (i = 0; i < drvdata->numvmidc; i++) {
>>> +        if (drvdata->no_quad_mmio)
>>> +            state->trcvmidcvr[i] = etm4x_split_read64(csa,
>>> TRCVMIDCVRn(i));
>>> +        else
>>> +            state->trcvmidcvr[i] = etm4x_read64(csa, TRCVMIDCVRn(i));
>>> +    }
>>>          state->trccidcctlr0 = etm4x_read32(csa, TRCCIDCCTLR0);
>>>        if (drvdata->numcidc > 4)
>>> @@ -1799,15 +1825,28 @@ static void __etm4_cpu_restore(struct
>>> etmv4_drvdata *drvdata)
>>>        }
>>>          for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
>>> -        etm4x_relaxed_write64(csa, state->trcacvr[i], TRCACVRn(i));
>>> -        etm4x_relaxed_write64(csa, state->trcacatr[i], TRCACATRn(i));
>>> +        if (drvdata->no_quad_mmio) {
>>> +            etm4x_split_write64(csa, state->trcacvr[i], TRCACVRn(i));
>>> +            etm4x_split_write64(csa, state->trcacatr[i], TRCACATRn(i));
>>> +        } else {
>>> +            etm4x_relaxed_write64(csa, state->trcacvr[i], TRCACVRn(i));
>>> +            etm4x_relaxed_write64(csa, state->trcacatr[i],
>>> TRCACATRn(i));
>>> +        }
>>>        }
>>>    -    for (i = 0; i < drvdata->numcidc; i++)
>>> -        etm4x_relaxed_write64(csa, state->trccidcvr[i], TRCCIDCVRn(i));
>>> +    for (i = 0; i < drvdata->numcidc; i++) {
>>> +        if (drvdata->no_quad_mmio)
>>> +            etm4x_split_write64(csa, state->trccidcvr[i],
>>> TRCCIDCVRn(i));
>>> +        else
>>> +            etm4x_relaxed_write64(csa, state->trccidcvr[i],
>>> TRCCIDCVRn(i));
>>> +    }
>>>    -    for (i = 0; i < drvdata->numvmidc; i++)
>>> -        etm4x_relaxed_write64(csa, state->trcvmidcvr[i],
>>> TRCVMIDCVRn(i));
>>> +    for (i = 0; i < drvdata->numvmidc; i++) {
>>> +        if (drvdata->no_quad_mmio)
>>> +            etm4x_split_write64(csa, state->trcvmidcvr[i],
>>> TRCVMIDCVRn(i));
>>> +        else
>>> +            etm4x_relaxed_write64(csa, state->trcvmidcvr[i],
>>> TRCVMIDCVRn(i));
>>> +    }
>>>          etm4x_relaxed_write32(csa, state->trccidcctlr0, TRCCIDCCTLR0);
>>>        if (drvdata->numcidc > 4)
>>> @@ -2047,8 +2086,10 @@ static int etm4_probe(struct device *dev, void
>>> __iomem *base, u32 etm_pid)
>>>         * isolates the manufacturer JEP106 ID in the PID.
>>>         * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>>>         */
>>> -    if ((init_arg.pid & 0x000FF000) == 0x00096000)
>>> +    if ((init_arg.pid & 0x000FF000) == 0x00096000) {
>>>            drvdata->mmio_external = true;
>>> +        drvdata->no_quad_mmio = true;
>>> +    }
>>>          /*
>>>         * Serialize against CPUHP callbacks to avoid race condition
>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h
>>> b/drivers/hwtracing/coresight/coresight-etm4x.h
>>> index cf4f9f2e1807..0650bcdff410 100644
>>> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
>>> @@ -1016,6 +1016,7 @@ struct etmv4_save_state {
>>>     *           the trace unit.
>>>     * @arch_features: Bitmap of arch features of etmv4 devices.
>>>     * @mmio_external: True if ETM considers MMIO an external access.
>>> + * @no_quad_mmio:  True if ETM does not support 64-bit (quad) access.
>>>     */
>>>    struct etmv4_drvdata {
>>>        void __iomem            *base;
>>> @@ -1069,6 +1070,7 @@ struct etmv4_drvdata {
>>>        bool                skip_power_up;
>>>        DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
>>>        bool                mmio_external;
>>> +    bool                no_quad_mmio;
>>>    };
>>>      /* Address comparator access types */
>>> @@ -1093,6 +1095,36 @@ void etm4_config_trace_mode(struct etmv4_config
>>> *config);
>>>    u64 etm4x_sysreg_read(u32 offset, bool _relaxed, bool _64bit);
>>>    void etm4x_sysreg_write(u64 val, u32 offset, bool _relaxed, bool
>>> _64bit);
>>>    +/* 64-bit aligned to convert 64-bit access to 2 ea. 32-bit access */
>>> +#pragma pack(push, 8)
>>> +
>>> +struct etm_quad_split {
>>> +    u32 lsw;
>>> +    u32 msw;
>>> +};
>>> +
>>> +#pragma pack(pop)
>>> +
>>> +static inline u64 etm4x_split_read64(struct csdev_access *csa,
>>> unsigned int offset)
>>> +{
>>> +    struct etm_quad_split container;
>>> +
>>> +    container.lsw = etm4x_read32(csa, offset);
>>> +    container.msw = etm4x_read32(csa, offset + sizeof(u32));
>>> +
>>> +    return *(u64 *) &container;
>>
>> Wouldn't this break with the "endianness" flip ? (Not that we have BE
>> implementations). Could we not combine the two values to a 64bit value
>> and pass that instead ?
> The split implementation writes/reads 32-bit words to/from 2 consecutive
> 32-bit aligned memory addresses independent of endianness so it doesn't
> care. I'm not sure I understand what you're getting at by combining the
> 2 ea. 32-bit values into a 1 ea. 64-bit value. The etm4x_split_read64
> and etm4x_split_write64 calls both use 64-bit values in and out.
> Internal to this code, both read and write accesses must use 32-bit values.
> 
>>
>> Similarly below.
>>
>> Suzuki
>>
>>> +}
>>> +
>>> +static inline void etm4x_split_write64(struct csdev_access *csa, u64
>>> quad, unsigned int offset)
>>> +{
>>> +    struct etm_quad_split container;
>>> +
>>> +    *(u64 *) &container = quad;
>>> +
>>> +    etm4x_relaxed_write32(csa, container.lsw, offset);
>>> +    etm4x_relaxed_write32(csa, container.msw, offset + sizeof(u32));
>>> +}
>>> +
>>>    static inline bool etm4x_is_ete(struct etmv4_drvdata *drvdata)
>>>    {
>>>        return drvdata->arch >= ETM_ARCH_ETE;
>>


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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Steve Clevenger]

On 1/23/2023 2:54 AM, Mike Leach wrote:
> Hi Steve,
> 
> On Sat, 21 Jan 2023 at 07:31, Steve Clevenger
> <scclevenger@os.amperecomputing.com> wrote:
>>
>>
>> Hi Mike,
>>
>> Comments in-line.
>>
>> Steve
>>
>> On 1/20/2023 3:45 AM, Mike Leach wrote:
>>> Hi Steve,
>>>
>>> On Fri, 20 Jan 2023 at 00:52, Steve Clevenger
>>> <scclevenger@os.amperecomputing.com> wrote:
>>>>
>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>> Computing design decision MMIO reads are considered the same as an
>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>> (now deprecated) is supported.
>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>
>>>> Add Ampere ETM PID required for Coresight ETM driver support.
>>>>
>>>> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
>>>> ---
>>>>  .../coresight/coresight-etm4x-core.c          | 36 +++++++++++++++----
>>>>  drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
>>>>  2 files changed, 32 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>> index 1cc052979e01..533be1928a09 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
>>>>         drvdata = dev_get_drvdata(init_arg->dev);
>>>>         csa = init_arg->csa;
>>>>
>>>
>>> As far as I can tell there appears to be an initialisation issue here.
>>> etm_probe()
>>> ...
>>> struct csdev_access access = { 0 };
>>> ...
>>> init_arg.csa = &access
>>>
>>> ::call=> etm4_init_arch_data(init_arg)
>>>
>>> Thus csa is uninitialised?
>> It looks to me csa is intended to be initialized to zero? In any case,
>> the Ampere check uses only the ETM pid, which is initialized directly above.
>>
> 
> Sorry, I should have been more explicit.
> 
> csa is the addressing abstraction used by all the underlying register
> read/write code.
> 
> It is initialised to {0} in the calling code, probably to avoid the
> kernel tests complaining about uninitialised use of a variable.
> 
> However in the etm4_init_csdev_access() function we are using a base
> address then it is initialised to:-
> 
> struct csdev_access {
>     io_mem = true;
>     *base = io_mem_base_addr;
> };
> 
> and in the access using system registers for an etm4 to:
> 
> struct csdev_access {
>     io_mem = false;
>     *read = etm4x_sysreg_read()
>     *write = etm4x_sysreg_write()
> };
Yes, csa is initialized indirectly in etm4_init_csdev_access via calls
to etm4_init_iomem_access and etm4_init_sysreg_access. So, you are
correct. csa is zero initialized for the call to etm4_detect_os_lock
(TRCOSLSR read) prior to my patch which clears TRCOSLAR.OSLK. The
TRCOSLSR read and TRCOSLAR.OSLK clear default to sysreg access. The csa
initialization problem is an existing bug I didn't see.
> 
> Thus all underlying register access can use the correct method for the device.
> 
>>>
>>>> +       /* Detect the support for OS Lock before we actually use it */
>>>> +       etm_detect_os_lock(drvdata, csa);
>>>> +
> 
> Thus passing a 0 init csa object to the etm_detect_os_lock()  fn above
> seems to be suspicious.
> 
>>>> +       /*
>>>> +        * For ETM implementations that consider MMIO an external access
>>>> +        * clear TRCOSLAR.OSLK early.
>>>> +        */
>>>> +       if (drvdata->mmio_external)
>>>> +               etm4_os_unlock_csa(drvdata, csa);
>>>> +
>>>>         /*
>>>>          * If we are unable to detect the access mechanism,
>>>>          * or unable to detect the trace unit type, fail
>>>> -        * early.
>>>> +        * early. Reset TRCOSLAR.OSLK if cleared.
>>>>          */
>>>> -       if (!etm4_init_csdev_access(drvdata, csa))
>>>> +       if (!etm4_init_csdev_access(drvdata, csa)) {
>>>
>>> This call initialises csa according to sysreg / iomem access requirements
> 
>> csa is initialized only when no drvdata->base exists.
> 
> Not so - csa is initialised in both circumstances as described above.
> 
>> Under what
>> circumstance would there be no ETM base given the recommended CoreSight
>> ACPI implementation? See the examples in ARM Document number: DEN0067.
> 
> 
> This will be used in the ETE devices (which share the etm4 driver), or
> any ETM4.6+ that uses the "arm,coresight-etm4x-sysreg" device tree
> binding (not sure what the ACPI equivalent is).
> 
> So, either way, you need an init csa, before passing it to the driver calls.
Agreed. See my summary above.

> 
> Later in the initialisation sequence we generate a coresight_device
> object which the csa is bound to, and finally if all is well the
> coresight_device is bound to drvdata at which point the device is
> ready for use.
> 
> It is unfortunate, but to handle the two methods of register access,
> the initilialisation process for the driver has become more
> complicated with ordering dependencies - to ensure that the rest of
> the driver remains simpler when accessing device registers.
> 
> As Suzuki mentioned - moving this specific lock requirement into the
> _init function would be clearer and ensure that the initialisation
> sequences were observed.
Getting back to the etm4_init_csdev_access implementation, if a
drvdata->base exists, etm4_init_sysreg_access is never called. The
driver doesn't initialize sysreg access if a memory map exists by
design. The existing Coresight ACPI specification only has the option of
describing the manufacturer trace implementation using descriptions of
memory mapped components.

> 
> Regards
> 
> Mike
> 
>>>
>>>
>>>
>>>> +               if (drvdata->mmio_external)
>>>> +                       etm4_os_lock(drvdata);
>>>>                 return;
>>>> +       }
>>>>
>>>> -       /* Detect the support for OS Lock before we actually use it */
>>>> -       etm_detect_os_lock(drvdata, csa);
>>>> +       /*
>>>> +        * Make sure all registers are accessible
>>>> +        * TRCOSLAR.OSLK may already be clear
>>>> +        */
>>>> +       if (!drvdata->mmio_external)
>>>> +               etm4_os_unlock_csa(drvdata, csa);
>>>>
>>>> -       /* Make sure all registers are accessible */
>>>> -       etm4_os_unlock_csa(drvdata, csa);
>>>>         etm4_cs_unlock(drvdata, csa);
>>>>
>>>>         etm4_check_arch_features(drvdata, init_arg->pid);
>>>> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
>>>>         init_arg.csa = &access;
>>>>         init_arg.pid = etm_pid;
>>>>
>>>> +       /*
>>>> +        * Ampere ETM v4.6 considers MMIO access as external. This mask
>>>> +        * isolates the manufacturer JEP106 ID in the PID.
>>>> +        * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>>>> +        */
>>>> +       if ((init_arg.pid & 0x000FF000) == 0x00096000)
>>>> +               drvdata->mmio_external = true;
>>>> +
>>>>         /*
>>>>          * Serialize against CPUHP callbacks to avoid race condition
>>>>          * between the smp call and saving the delayed probe.
>>>> @@ -2192,6 +2215,7 @@ static const struct amba_id etm4_ids[] = {
>>>>         CS_AMBA_ID(0x000bb95e),                 /* Cortex-A57 */
>>>>         CS_AMBA_ID(0x000bb95a),                 /* Cortex-A72 */
>>>>         CS_AMBA_ID(0x000bb959),                 /* Cortex-A73 */
>>>> +       CS_AMBA_UCI_ID(0x00096000, uci_id_etm4),/* Ampere ARMv8 */
>>>>         CS_AMBA_UCI_ID(0x000bb9da, uci_id_etm4),/* Cortex-A35 */
>>>>         CS_AMBA_UCI_ID(0x000bbd05, uci_id_etm4),/* Cortex-A55 */
>>>>         CS_AMBA_UCI_ID(0x000bbd0a, uci_id_etm4),/* Cortex-A75 */
>>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
>>>> index 4b21bb79f168..cf4f9f2e1807 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
>>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
>>>> @@ -1015,6 +1015,7 @@ struct etmv4_save_state {
>>>>   * @skip_power_up: Indicates if an implementation can skip powering up
>>>>   *                the trace unit.
>>>>   * @arch_features: Bitmap of arch features of etmv4 devices.
>>>> + * @mmio_external: True if ETM considers MMIO an external access.
>>>>   */
>>>>  struct etmv4_drvdata {
>>>>         void __iomem                    *base;
>>>> @@ -1067,6 +1068,7 @@ struct etmv4_drvdata {
>>>>         bool                            state_needs_restore;
>>>>         bool                            skip_power_up;
>>>>         DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
>>>
>>> Rather than continue to add bools - is it not worthwhile adding to the
>>> bitmap above and extending the arch features API to allow a
>>> "has_feature" call?
>> I can look into this. I agree using a bool for every exception doesn't
>> scale well. Referring to one Suzuki Poulose review comment, his proposal
>> to clear TRCOSLAR.OSLK early for all parts would mean one of these bools
>> could go away. Otherwise, possibly add one (or more) bit definitions for
>> use by the etm4_disable_arch_specific call. The order of this call would
>> need to change, depending.
>>
>>>
>>>> +       bool                            mmio_external;
>>>>  };
>>>>
>>>>  /* Address comparator access types */
>>>> --
>>>> 2.25.1
>>>>
>>> Regards
>>>
>>> Mike
> 
> 
> 

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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Steve Clevenger]

On 1/23/2023 9:33 AM, Suzuki K Poulose wrote:
> On 23/01/2023 17:22, Steve Clevenger wrote:
>>
>>
>> On 1/23/2023 2:54 AM, Suzuki K Poulose wrote:
>>> On 21/01/2023 07:30, Steve Clevenger wrote:
>>>>
>>>> Hi Suzuki,
>>>>
>>>> Comments in-line. Please note the approach I attempted while adding in
>>>> the Ampere support was to otherwise not disturb existing driver code
>>>> for
>>>> non-Ampere parts.
>>>>
>>>> Steve
>>>>
>>>> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>>>>> Hi Steve
>>>>>
>>>>> Thanks for the patches. Have a few comments below.
>>>>>
>>>>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
>>>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>>>> Computing design decision MMIO reads are considered the same as an
>>>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>>>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>>>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>>>> (now deprecated) is supported.
>>>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>>
>>>>> Please could you add this erratum to the :
>>>>>
>>>>> Documentation/arm64/silicon-errata.rst ?
>>>>>
>>>>> Given the ETM is v4.6, doesn't it support system instructions and
>>>>> that is causing this issue of "MMIO access is considered external" ?
>>>>> If it does, I think we should drop all of this and simply wire the
>>>>> system instruction access support.
>>>
>>>> That's not the issue in this case. This MMIO access should've been
>>>> allowed by the Ampere ETMv4.6 implementation.  Based on comments I've
>>>
>>> That doesn't answe the question. Please could you confirm the value of
>>> ID_AA64DFR0_EL1 on your system ?
>> This ID_AA64DFR0_EL1 value came from a TRACE32 debug session connected
>> to this part. The ID_AA64DFR0_EL1 value is 0x000F01F210307619. So,
>> TraceVer, bits [7:4] are b0001. My understanding is the system register
>> interface must be implemented on all ETMv4.6 parts.
> 
> So, I don't understand why we are pushing towards enabling the
> "obsolete" MMIO interface ? Is this because "ACPI" mandates it ?
> Then, please don't. The spec needs an update to reflect the ETMs
> with sysreg access and ETEs.
> 
> Why not stick to the system register access* ?
> 
> * PS: The ACPI support for the ETM/ETE needs additional changes to the
> CoreSight driver, *not* the CoreSight ACPI spec. @Anshuman is working on
> this at the moment and will be available soon.
> 
> The hack patch below should be sufficient to give it a try and if it works.
I don't understand your postscript. Certainly there's driver work to be
done, but I also think the DEN0067 CoreSight ACPI specification needs
update. There's no example for defining a trace implementation without
memory mapped component descriptions. Considering the ACPI as it exists,
the component graphs are the most important. Please see my last exchange
with Mike Leach.

My patches were submitted based on the existing CoreSight driver, not
what it should be. Ampere does not have the flexibility to wait for a
decision on some details we've discussed. I'm available to work through
any concerns the maintainers have with my submissions. What is the best
way forward here?

> Kind regards
> Suzuki
> 
>>
>>>
>>> Or, are you able to try this on your ACPI based system and see if you
>>> are able to use the etm ? (UNTESTED hack !)
>>>
>>>
>>> diff --git a/drivers/acpi/acpi_amba.c b/drivers/acpi/acpi_amba.c
>>> index f5b443ab01c2..099966cbac5a 100644
>>> --- a/drivers/acpi/acpi_amba.c
>>> +++ b/drivers/acpi/acpi_amba.c
>>> @@ -22,7 +22,6 @@
>>>   static const struct acpi_device_id amba_id_list[] = {
>>>       {"ARMH0061", 0}, /* PL061 GPIO Device */
>>>       {"ARMH0330", 0}, /* ARM DMA Controller DMA-330 */
>>> -    {"ARMHC500", 0}, /* ARM CoreSight ETM4x */
>>>       {"ARMHC501", 0}, /* ARM CoreSight ETR */
>>>       {"ARMHC502", 0}, /* ARM CoreSight STM */
>>>       {"ARMHC503", 0}, /* ARM CoreSight Debug */
>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> index 1ea8f173cca0..66670533fd54 100644
>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> @@ -3,6 +3,7 @@
>>>    * Copyright (c) 2014, The Linux Foundation. All rights reserved.
>>>    */
>>>
>>> +#include <linux/acpi.h>
>>>   #include <linux/bitops.h>
>>>   #include <linux/kernel.h>
>>>   #include <linux/moduleparam.h>
>>> @@ -2286,12 +2287,22 @@ static const struct of_device_id
>>> etm4_sysreg_match[] = {
>>>       {}
>>>   };
>>>
>>> +#ifdef CONFIG_ACPI
>>> +static const struct acpi_device_id etm4x_acpi_ids[] = {
>>> +    {"ARMHC500", 0}, /* ARM CoreSight ETM4x */
>>> +    {}
>>> +};
>>> +
>>> +MODULE_DEVICE_TABLE(acpi, etm4x_acpi_ids);
>>> +#endif
>>> +
>>>   static struct platform_driver etm4_platform_driver = {
>>>       .probe        = etm4_probe_platform_dev,
>>>       .remove        = etm4_remove_platform_dev,
>>>       .driver            = {
>>>           .name            = "coresight-etm4x",
>>>           .of_match_table        = etm4_sysreg_match,
>>> +        .acpi_match_table = ACPI_PTR(etm4x_acpi_ids),
>>>           .suppress_bind_attrs    = true,
>>>       },
>>>   };
>>>
>>>
>>>
>>>
>>>> read in the driver code, the MMIO read access to TRCIDR1 occurs after a
>>>> TRCDEVARCH access. The comments suggest this was to accommodate
>>>> potentially unreliable TRCDEVARCH (and TRCIDR1) values. This Ampere
>>>> ETMv4.6 allows an MMIO access to TRCDEVARCH, but not to TRCIDR1 unless
>>>> the TRCOSLAR.OSLK lock is cleared first.
>>>>
>>>>>
>>>>>>
>>>>>> Add Ampere ETM PID required for Coresight ETM driver support.
>>>>>>
>>>>>> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
>>>>>> ---
>>>>>>     .../coresight/coresight-etm4x-core.c          | 36
>>>>>> +++++++++++++++----
>>>>>>     drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
>>>>>>     2 files changed, 32 insertions(+), 6 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>>> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>>> index 1cc052979e01..533be1928a09 100644
>>>>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>>> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
>>>>>>         drvdata = dev_get_drvdata(init_arg->dev);
>>>>>>         csa = init_arg->csa;
>>>>>>     +    /* Detect the support for OS Lock before we actually use
>>>>>> it */
>>>>>> +    etm_detect_os_lock(drvdata, csa);
>>>>>> + > +    /*
>>>>>> +     * For ETM implementations that consider MMIO an external access
>>>>>> +     * clear TRCOSLAR.OSLK early.
>>>>>> +     */
>>>>>> +    if (drvdata->mmio_external)
>>>>>> +        etm4_os_unlock_csa(drvdata, csa);
>>>>>> +
>>>>>>         /*
>>>>>>          * If we are unable to detect the access mechanism,
>>>>>>          * or unable to detect the trace unit type, fail
>>>>>> -     * early.
>>>>>> +     * early. Reset TRCOSLAR.OSLK if cleared.
>>>>>>          */
>>>>>> -    if (!etm4_init_csdev_access(drvdata, csa))
>>>>>> +    if (!etm4_init_csdev_access(drvdata, csa)) {
>>>>>> +        if (drvdata->mmio_external)
>>>>>> +            etm4_os_lock(drvdata);
>>>>>
>>>>> Couldn't this unlock/lock sequence be moved into the
>>>>> etm4_init_csdev_iomem_access() where it actually matters ?
>>>>>
>>>>> Or thinking more about it, we could actually move the unlock step
>>>>> early
>>>>> for all ETMs irrespective of whether they are affected by this
>>>>> erratum.
>>>>> Of course, putting this back, if we fail to detect the ETM properly.
>>>>> I don't see any issue with that.
>>>
>>>
>>>> I agree the lock could be cleared earlier in the code. That's what this
>>>> patch does for Ampere. If it's decided ok to do for other (or all)
>>>> manufacturers, then the Ampere specific ID check goes away in this
>>>> place. The Ampere ID check (and flag) to determine whether the [Patch
>>>> 2/3] 64-bit access is split into 2 ea. 32-bit accesses would remain, or
>>>> use an existing feature mask as suggested by Mike Leach in a later
>>>> review.
>>>>
>>>>>
>>>>>>             return;
>>>>>> +    }
>>>>>>     -    /* Detect the support for OS Lock before we actually use
>>>>>> it */
>>>>>> -    etm_detect_os_lock(drvdata, csa);
>>>>>> +    /*
>>>>>> +     * Make sure all registers are accessible
>>>>>> +     * TRCOSLAR.OSLK may already be clear
>>>>>> +     */
>>>>>> +    if (!drvdata->mmio_external)
>>>>>> +        etm4_os_unlock_csa(drvdata, csa);
>>>>>>     -    /* Make sure all registers are accessible */
>>>>>> -    etm4_os_unlock_csa(drvdata, csa);
>>>>>>         etm4_cs_unlock(drvdata, csa);
>>>>>>           etm4_check_arch_features(drvdata, init_arg->pid);
>>>>>> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void
>>>>>> __iomem *base, u32 etm_pid)
>>>>>>         init_arg.csa = &access;
>>>>>>         init_arg.pid = etm_pid;
>>>>>>     +    /*
>>>>>> +     * Ampere ETM v4.6 considers MMIO access as external. This mask
>>>>>> +     * isolates the manufacturer JEP106 ID in the PID.
>>>>>> +     * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>>>>>> +     */
>>>>>
>>>>> Does it affect all Ampere ETMs ? You seem to be ignoring the
>>>>> PDIR1.PART_1, PDIR0_PART_0 fields, which happens to be 0.
>>>
>>>> This is the first Ampere ETMv4.x implementation. I wrote the ID check
>>>> like this specifically because Ampere does not intend to address this
>>>> for ETM designs in progress.
>>>
>>> I would recommend to make this mask stricter and apply this to the
>>> current implementation. When there are more, we could add this here,
>>> rather than having to leave this work around for all the possible cores.
>>>
>>>>
>>>>>
>>>>>> +    if ((init_arg.pid & 0x000FF000) == 0x00096000)
>>>>>> +        drvdata->mmio_external = true;
>>>>> Like I said, we may be able to get rid of this flag and do the step
>>>>> for
>>>>> all ETMs. But before all of that, I would like to see if this is
>>>>> problem
>>>>> because we are skipping the system instruction route.
>>>>>
>>>
>>>> We understand MMIO access is deprecated going forward. There is other
>>>> Linux code to be concerned about. For example, AMBA code reads the
>>>> component PID/CID. This discovery code uses mapped values digested from
>>>> the CoreSight ACPI which are the descriptions and graphs for the
>>>
>>> With the "proposed" ACPI support for system register, AMBA would not be
>>> involved at all.
>>>
>>>> manufacturer trace implementation. There may be other Linux code I'm
>>>> not
>>>> aware. Note the ASL examples in ARM Document number: DEN0067 specify
>>>> MMIO locations for every CoreSight component.
>>>
>>> Yes, but this was never updated to cover the system register based
>>> implementations. I will chase this up.
>>>
>>>
>>> Suzuki
>>>
> 

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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Suzuki K Poulose]

On 23/01/2023 19:48, Steve Clevenger wrote:
> 
> 
> On 1/23/2023 9:33 AM, Suzuki K Poulose wrote:
>> On 23/01/2023 17:22, Steve Clevenger wrote:
>>>
>>>
>>> On 1/23/2023 2:54 AM, Suzuki K Poulose wrote:
>>>> On 21/01/2023 07:30, Steve Clevenger wrote:
>>>>>
>>>>> Hi Suzuki,
>>>>>
>>>>> Comments in-line. Please note the approach I attempted while adding in
>>>>> the Ampere support was to otherwise not disturb existing driver code
>>>>> for
>>>>> non-Ampere parts.
>>>>>
>>>>> Steve
>>>>>
>>>>> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>>>>>> Hi Steve
>>>>>>
>>>>>> Thanks for the patches. Have a few comments below.
>>>>>>
>>>>>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>>>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
>>>>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>>>>> Computing design decision MMIO reads are considered the same as an
>>>>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>>>>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>>>>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>>>>> (now deprecated) is supported.
>>>>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>>>
>>>>>> Please could you add this erratum to the :
>>>>>>
>>>>>> Documentation/arm64/silicon-errata.rst ?
>>>>>>
>>>>>> Given the ETM is v4.6, doesn't it support system instructions and
>>>>>> that is causing this issue of "MMIO access is considered external" ?
>>>>>> If it does, I think we should drop all of this and simply wire the
>>>>>> system instruction access support.
>>>>
>>>>> That's not the issue in this case. This MMIO access should've been
>>>>> allowed by the Ampere ETMv4.6 implementation.  Based on comments I've
>>>>
>>>> That doesn't answe the question. Please could you confirm the value of
>>>> ID_AA64DFR0_EL1 on your system ?
>>> This ID_AA64DFR0_EL1 value came from a TRACE32 debug session connected
>>> to this part. The ID_AA64DFR0_EL1 value is 0x000F01F210307619. So,
>>> TraceVer, bits [7:4] are b0001. My understanding is the system register
>>> interface must be implemented on all ETMv4.6 parts.
>>
>> So, I don't understand why we are pushing towards enabling the
>> "obsolete" MMIO interface ? Is this because "ACPI" mandates it ?
>> Then, please don't. The spec needs an update to reflect the ETMs
>> with sysreg access and ETEs.
>>
>> Why not stick to the system register access* ?
>>
>> * PS: The ACPI support for the ETM/ETE needs additional changes to the
>> CoreSight driver, *not* the CoreSight ACPI spec. @Anshuman is working on
>> this at the moment and will be available soon.
>>
>> The hack patch below should be sufficient to give it a try and if it works.

> I don't understand your postscript. Certainly there's driver work to be
> done, but I also think the DEN0067 CoreSight ACPI specification needs

The issue is having a single HID for ETMs (which from a spec point of
view makes sense for) with and without MMIO access. That brings two
different components in Linux (AMBA hook for ACPI and a platform driver)
compete for the said HID. There are other reasons to disconnect the
CoreSight from AMBA framework and manage them directly [0].

So, that needs a bit of ground work to move ETM driver away from AMBA
and then we can have a single driver handling both devices. It is much
easier on DT based systems, as we have different compatible strings.

> update. There's no example for defining a trace implementation without
> memory mapped component descriptions. Considering the ACPI as it exists,

I have raised this with the concerned people in Arm and can share the 
update via other channels once we have it. Basically we should be able
to reuse the one for MMIO based systems, except the memory resource.
The Graph connections remain unaffected by this change. This never
made it to the document.

> the component graphs are the most important. Please see my last exchange
> with Mike Leach.
> 
> My patches were submitted based on the existing CoreSight driver, not
> what it should be. Ampere does not have the flexibility to wait for a > decision on some details we've discussed. I'm available to work through

Understand. But that doesn't mean we can push something in that is not
meant to work the way it should.

> any concerns the maintainers have with my submissions. What is the best
> way forward here?

If this is a system with system instruction access, it should be 
described as such and can be supported when the above mentioned
change is in the kernel.

Suzuki


> 
>> Kind regards
>> Suzuki
>>
>>>
>>>>
>>>> Or, are you able to try this on your ACPI based system and see if you
>>>> are able to use the etm ? (UNTESTED hack !)
>>>>
>>>>
>>>> diff --git a/drivers/acpi/acpi_amba.c b/drivers/acpi/acpi_amba.c
>>>> index f5b443ab01c2..099966cbac5a 100644
>>>> --- a/drivers/acpi/acpi_amba.c
>>>> +++ b/drivers/acpi/acpi_amba.c
>>>> @@ -22,7 +22,6 @@
>>>>    static const struct acpi_device_id amba_id_list[] = {
>>>>        {"ARMH0061", 0}, /* PL061 GPIO Device */
>>>>        {"ARMH0330", 0}, /* ARM DMA Controller DMA-330 */
>>>> -    {"ARMHC500", 0}, /* ARM CoreSight ETM4x */
>>>>        {"ARMHC501", 0}, /* ARM CoreSight ETR */
>>>>        {"ARMHC502", 0}, /* ARM CoreSight STM */
>>>>        {"ARMHC503", 0}, /* ARM CoreSight Debug */
>>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>> index 1ea8f173cca0..66670533fd54 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>> @@ -3,6 +3,7 @@
>>>>     * Copyright (c) 2014, The Linux Foundation. All rights reserved.
>>>>     */
>>>>
>>>> +#include <linux/acpi.h>
>>>>    #include <linux/bitops.h>
>>>>    #include <linux/kernel.h>
>>>>    #include <linux/moduleparam.h>
>>>> @@ -2286,12 +2287,22 @@ static const struct of_device_id
>>>> etm4_sysreg_match[] = {
>>>>        {}
>>>>    };
>>>>
>>>> +#ifdef CONFIG_ACPI
>>>> +static const struct acpi_device_id etm4x_acpi_ids[] = {
>>>> +    {"ARMHC500", 0}, /* ARM CoreSight ETM4x */
>>>> +    {}
>>>> +};
>>>> +
>>>> +MODULE_DEVICE_TABLE(acpi, etm4x_acpi_ids);
>>>> +#endif
>>>> +
>>>>    static struct platform_driver etm4_platform_driver = {
>>>>        .probe        = etm4_probe_platform_dev,
>>>>        .remove        = etm4_remove_platform_dev,
>>>>        .driver            = {
>>>>            .name            = "coresight-etm4x",
>>>>            .of_match_table        = etm4_sysreg_match,
>>>> +        .acpi_match_table = ACPI_PTR(etm4x_acpi_ids),
>>>>            .suppress_bind_attrs    = true,
>>>>        },
>>>>    };
>>>>
>>>>
>>>>
>>>>
>>>>> read in the driver code, the MMIO read access to TRCIDR1 occurs after a
>>>>> TRCDEVARCH access. The comments suggest this was to accommodate
>>>>> potentially unreliable TRCDEVARCH (and TRCIDR1) values. This Ampere
>>>>> ETMv4.6 allows an MMIO access to TRCDEVARCH, but not to TRCIDR1 unless
>>>>> the TRCOSLAR.OSLK lock is cleared first.
>>>>>
>>>>>>
>>>>>>>
>>>>>>> Add Ampere ETM PID required for Coresight ETM driver support.
>>>>>>>
>>>>>>> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
>>>>>>> ---
>>>>>>>      .../coresight/coresight-etm4x-core.c          | 36
>>>>>>> +++++++++++++++----
>>>>>>>      drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
>>>>>>>      2 files changed, 32 insertions(+), 6 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>>>> b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>>>> index 1cc052979e01..533be1928a09 100644
>>>>>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>>>> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
>>>>>>>          drvdata = dev_get_drvdata(init_arg->dev);
>>>>>>>          csa = init_arg->csa;
>>>>>>>      +    /* Detect the support for OS Lock before we actually use
>>>>>>> it */
>>>>>>> +    etm_detect_os_lock(drvdata, csa);
>>>>>>> + > +    /*
>>>>>>> +     * For ETM implementations that consider MMIO an external access
>>>>>>> +     * clear TRCOSLAR.OSLK early.
>>>>>>> +     */
>>>>>>> +    if (drvdata->mmio_external)
>>>>>>> +        etm4_os_unlock_csa(drvdata, csa);
>>>>>>> +
>>>>>>>          /*
>>>>>>>           * If we are unable to detect the access mechanism,
>>>>>>>           * or unable to detect the trace unit type, fail
>>>>>>> -     * early.
>>>>>>> +     * early. Reset TRCOSLAR.OSLK if cleared.
>>>>>>>           */
>>>>>>> -    if (!etm4_init_csdev_access(drvdata, csa))
>>>>>>> +    if (!etm4_init_csdev_access(drvdata, csa)) {
>>>>>>> +        if (drvdata->mmio_external)
>>>>>>> +            etm4_os_lock(drvdata);
>>>>>>
>>>>>> Couldn't this unlock/lock sequence be moved into the
>>>>>> etm4_init_csdev_iomem_access() where it actually matters ?
>>>>>>
>>>>>> Or thinking more about it, we could actually move the unlock step
>>>>>> early
>>>>>> for all ETMs irrespective of whether they are affected by this
>>>>>> erratum.
>>>>>> Of course, putting this back, if we fail to detect the ETM properly.
>>>>>> I don't see any issue with that.
>>>>
>>>>
>>>>> I agree the lock could be cleared earlier in the code. That's what this
>>>>> patch does for Ampere. If it's decided ok to do for other (or all)
>>>>> manufacturers, then the Ampere specific ID check goes away in this
>>>>> place. The Ampere ID check (and flag) to determine whether the [Patch
>>>>> 2/3] 64-bit access is split into 2 ea. 32-bit accesses would remain, or
>>>>> use an existing feature mask as suggested by Mike Leach in a later
>>>>> review.
>>>>>
>>>>>>
>>>>>>>              return;
>>>>>>> +    }
>>>>>>>      -    /* Detect the support for OS Lock before we actually use
>>>>>>> it */
>>>>>>> -    etm_detect_os_lock(drvdata, csa);
>>>>>>> +    /*
>>>>>>> +     * Make sure all registers are accessible
>>>>>>> +     * TRCOSLAR.OSLK may already be clear
>>>>>>> +     */
>>>>>>> +    if (!drvdata->mmio_external)
>>>>>>> +        etm4_os_unlock_csa(drvdata, csa);
>>>>>>>      -    /* Make sure all registers are accessible */
>>>>>>> -    etm4_os_unlock_csa(drvdata, csa);
>>>>>>>          etm4_cs_unlock(drvdata, csa);
>>>>>>>            etm4_check_arch_features(drvdata, init_arg->pid);
>>>>>>> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void
>>>>>>> __iomem *base, u32 etm_pid)
>>>>>>>          init_arg.csa = &access;
>>>>>>>          init_arg.pid = etm_pid;
>>>>>>>      +    /*
>>>>>>> +     * Ampere ETM v4.6 considers MMIO access as external. This mask
>>>>>>> +     * isolates the manufacturer JEP106 ID in the PID.
>>>>>>> +     * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>>>>>>> +     */
>>>>>>
>>>>>> Does it affect all Ampere ETMs ? You seem to be ignoring the
>>>>>> PDIR1.PART_1, PDIR0_PART_0 fields, which happens to be 0.
>>>>
>>>>> This is the first Ampere ETMv4.x implementation. I wrote the ID check
>>>>> like this specifically because Ampere does not intend to address this
>>>>> for ETM designs in progress.
>>>>
>>>> I would recommend to make this mask stricter and apply this to the
>>>> current implementation. When there are more, we could add this here,
>>>> rather than having to leave this work around for all the possible cores.
>>>>
>>>>>
>>>>>>
>>>>>>> +    if ((init_arg.pid & 0x000FF000) == 0x00096000)
>>>>>>> +        drvdata->mmio_external = true;
>>>>>> Like I said, we may be able to get rid of this flag and do the step
>>>>>> for
>>>>>> all ETMs. But before all of that, I would like to see if this is
>>>>>> problem
>>>>>> because we are skipping the system instruction route.
>>>>>>
>>>>
>>>>> We understand MMIO access is deprecated going forward. There is other
>>>>> Linux code to be concerned about. For example, AMBA code reads the
>>>>> component PID/CID. This discovery code uses mapped values digested from
>>>>> the CoreSight ACPI which are the descriptions and graphs for the
>>>>
>>>> With the "proposed" ACPI support for system register, AMBA would not be
>>>> involved at all.
>>>>
>>>>> manufacturer trace implementation. There may be other Linux code I'm
>>>>> not
>>>>> aware. Note the ASL examples in ARM Document number: DEN0067 specify
>>>>> MMIO locations for every CoreSight component.
>>>>
>>>> Yes, but this was never updated to cover the system register based
>>>> implementations. I will chase this up.
>>>>
>>>>
>>>> Suzuki
>>>>
>>


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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Suzuki K Poulose]

On 23/01/2023 19:47, Steve Clevenger wrote:
> 
> 
> On 1/23/2023 2:54 AM, Mike Leach wrote:
>> Hi Steve,
>>
>> On Sat, 21 Jan 2023 at 07:31, Steve Clevenger
>> <scclevenger@os.amperecomputing.com> wrote:
>>>
>>>
>>> Hi Mike,
>>>
>>> Comments in-line.
>>>
>>> Steve
>>>
>>> On 1/20/2023 3:45 AM, Mike Leach wrote:
>>>> Hi Steve,
>>>>
>>>> On Fri, 20 Jan 2023 at 00:52, Steve Clevenger
>>>> <scclevenger@os.amperecomputing.com> wrote:
>>>>>
>>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 access.
>>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>>> Computing design decision MMIO reads are considered the same as an
>>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>>> (now deprecated) is supported.
>>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>>
>>>>> Add Ampere ETM PID required for Coresight ETM driver support.
>>>>>
>>>>> Signed-off-by: Steve Clevenger <scclevenger@os.amperecomputing.com>
>>>>> ---
>>>>>   .../coresight/coresight-etm4x-core.c          | 36 +++++++++++++++----
>>>>>   drivers/hwtracing/coresight/coresight-etm4x.h |  2 ++
>>>>>   2 files changed, 32 insertions(+), 6 deletions(-)
>>>>>
>>>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>> index 1cc052979e01..533be1928a09 100644
>>>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>>>> @@ -1091,19 +1091,34 @@ static void etm4_init_arch_data(void *info)
>>>>>          drvdata = dev_get_drvdata(init_arg->dev);
>>>>>          csa = init_arg->csa;
>>>>>
>>>>
>>>> As far as I can tell there appears to be an initialisation issue here.
>>>> etm_probe()
>>>> ...
>>>> struct csdev_access access = { 0 };
>>>> ...
>>>> init_arg.csa = &access
>>>>
>>>> ::call=> etm4_init_arch_data(init_arg)
>>>>
>>>> Thus csa is uninitialised?
>>> It looks to me csa is intended to be initialized to zero? In any case,
>>> the Ampere check uses only the ETM pid, which is initialized directly above.
>>>
>>
>> Sorry, I should have been more explicit.
>>
>> csa is the addressing abstraction used by all the underlying register
>> read/write code.
>>
>> It is initialised to {0} in the calling code, probably to avoid the
>> kernel tests complaining about uninitialised use of a variable.
>>
>> However in the etm4_init_csdev_access() function we are using a base
>> address then it is initialised to:-
>>
>> struct csdev_access {
>>      io_mem = true;
>>      *base = io_mem_base_addr;
>> };
>>
>> and in the access using system registers for an etm4 to:
>>
>> struct csdev_access {
>>      io_mem = false;
>>      *read = etm4x_sysreg_read()
>>      *write = etm4x_sysreg_write()
>> };
> Yes, csa is initialized indirectly in etm4_init_csdev_access via calls
> to etm4_init_iomem_access and etm4_init_sysreg_access. So, you are
> correct. csa is zero initialized for the call to etm4_detect_os_lock
> (TRCOSLSR read) prior to my patch which clears TRCOSLAR.OSLK. The
> TRCOSLSR read and TRCOSLAR.OSLK clear default to sysreg access. The csa
> initialization problem is an existing bug I didn't see.
>>
>> Thus all underlying register access can use the correct method for the device.
>>
>>>>
>>>>> +       /* Detect the support for OS Lock before we actually use it */
>>>>> +       etm_detect_os_lock(drvdata, csa);
>>>>> +
>>
>> Thus passing a 0 init csa object to the etm_detect_os_lock()  fn above
>> seems to be suspicious.
>>
>>>>> +       /*
>>>>> +        * For ETM implementations that consider MMIO an external access
>>>>> +        * clear TRCOSLAR.OSLK early.
>>>>> +        */
>>>>> +       if (drvdata->mmio_external)
>>>>> +               etm4_os_unlock_csa(drvdata, csa);
>>>>> +
>>>>>          /*
>>>>>           * If we are unable to detect the access mechanism,
>>>>>           * or unable to detect the trace unit type, fail
>>>>> -        * early.
>>>>> +        * early. Reset TRCOSLAR.OSLK if cleared.
>>>>>           */
>>>>> -       if (!etm4_init_csdev_access(drvdata, csa))
>>>>> +       if (!etm4_init_csdev_access(drvdata, csa)) {
>>>>
>>>> This call initialises csa according to sysreg / iomem access requirements
>>
>>> csa is initialized only when no drvdata->base exists.
>>
>> Not so - csa is initialised in both circumstances as described above.
>>
>>> Under what
>>> circumstance would there be no ETM base given the recommended CoreSight
>>> ACPI implementation? See the examples in ARM Document number: DEN0067.
>>
>>
>> This will be used in the ETE devices (which share the etm4 driver), or
>> any ETM4.6+ that uses the "arm,coresight-etm4x-sysreg" device tree
>> binding (not sure what the ACPI equivalent is).
>>
>> So, either way, you need an init csa, before passing it to the driver calls.
> Agreed. See my summary above.
> 
>>
>> Later in the initialisation sequence we generate a coresight_device
>> object which the csa is bound to, and finally if all is well the
>> coresight_device is bound to drvdata at which point the device is
>> ready for use.
>>
>> It is unfortunate, but to handle the two methods of register access,
>> the initilialisation process for the driver has become more
>> complicated with ordering dependencies - to ensure that the rest of
>> the driver remains simpler when accessing device registers.
>>
>> As Suzuki mentioned - moving this specific lock requirement into the
>> _init function would be clearer and ensure that the initialisation
>> sequences were observed.
> Getting back to the etm4_init_csdev_access implementation, if a
> drvdata->base exists, etm4_init_sysreg_access is never called. The
> driver doesn't initialize sysreg access if a memory map exists by
> design. The existing Coresight ACPI specification only has the option of
> describing the manufacturer trace implementation using descriptions of
> memory mapped components.

As mentioned in my previous comments, this is only a matter of
updating the spec. You should be able to use everything same for
the ETM, excluding the "MMIO" region.

i.e,

      Device(CPU0) {
         Name(_HID, "ACPI0010"),
         ...
         Device(ETM0) {
           Name (_HID, "ARMHC500")      // ETM
           Name (_CID, "ARMHC500")      // ETM

           /* No _CRS Memory Resource  for sysreg access */
	  /* Graph Connections as usual, if any ATB is connected */
	  Name (_DSD , Package () {
	  ...
	  })
           ...
         } // ETM0
     } // CPU0


Suzuki

> 
>>
>> Regards
>>
>> Mike
>>
>>>>
>>>>
>>>>
>>>>> +               if (drvdata->mmio_external)
>>>>> +                       etm4_os_lock(drvdata);
>>>>>                  return;
>>>>> +       }
>>>>>
>>>>> -       /* Detect the support for OS Lock before we actually use it */
>>>>> -       etm_detect_os_lock(drvdata, csa);
>>>>> +       /*
>>>>> +        * Make sure all registers are accessible
>>>>> +        * TRCOSLAR.OSLK may already be clear
>>>>> +        */
>>>>> +       if (!drvdata->mmio_external)
>>>>> +               etm4_os_unlock_csa(drvdata, csa);
>>>>>
>>>>> -       /* Make sure all registers are accessible */
>>>>> -       etm4_os_unlock_csa(drvdata, csa);
>>>>>          etm4_cs_unlock(drvdata, csa);
>>>>>
>>>>>          etm4_check_arch_features(drvdata, init_arg->pid);
>>>>> @@ -2027,6 +2042,14 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
>>>>>          init_arg.csa = &access;
>>>>>          init_arg.pid = etm_pid;
>>>>>
>>>>> +       /*
>>>>> +        * Ampere ETM v4.6 considers MMIO access as external. This mask
>>>>> +        * isolates the manufacturer JEP106 ID in the PID.
>>>>> +        * TRCPIDR2 (JEDC|DES_1) << 16 | TRCPIDR1 (DES_0) << 8)
>>>>> +        */
>>>>> +       if ((init_arg.pid & 0x000FF000) == 0x00096000)
>>>>> +               drvdata->mmio_external = true;
>>>>> +
>>>>>          /*
>>>>>           * Serialize against CPUHP callbacks to avoid race condition
>>>>>           * between the smp call and saving the delayed probe.
>>>>> @@ -2192,6 +2215,7 @@ static const struct amba_id etm4_ids[] = {
>>>>>          CS_AMBA_ID(0x000bb95e),                 /* Cortex-A57 */
>>>>>          CS_AMBA_ID(0x000bb95a),                 /* Cortex-A72 */
>>>>>          CS_AMBA_ID(0x000bb959),                 /* Cortex-A73 */
>>>>> +       CS_AMBA_UCI_ID(0x00096000, uci_id_etm4),/* Ampere ARMv8 */
>>>>>          CS_AMBA_UCI_ID(0x000bb9da, uci_id_etm4),/* Cortex-A35 */
>>>>>          CS_AMBA_UCI_ID(0x000bbd05, uci_id_etm4),/* Cortex-A55 */
>>>>>          CS_AMBA_UCI_ID(0x000bbd0a, uci_id_etm4),/* Cortex-A75 */
>>>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
>>>>> index 4b21bb79f168..cf4f9f2e1807 100644
>>>>> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
>>>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
>>>>> @@ -1015,6 +1015,7 @@ struct etmv4_save_state {
>>>>>    * @skip_power_up: Indicates if an implementation can skip powering up
>>>>>    *                the trace unit.
>>>>>    * @arch_features: Bitmap of arch features of etmv4 devices.
>>>>> + * @mmio_external: True if ETM considers MMIO an external access.
>>>>>    */
>>>>>   struct etmv4_drvdata {
>>>>>          void __iomem                    *base;
>>>>> @@ -1067,6 +1068,7 @@ struct etmv4_drvdata {
>>>>>          bool                            state_needs_restore;
>>>>>          bool                            skip_power_up;
>>>>>          DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
>>>>
>>>> Rather than continue to add bools - is it not worthwhile adding to the
>>>> bitmap above and extending the arch features API to allow a
>>>> "has_feature" call?
>>> I can look into this. I agree using a bool for every exception doesn't
>>> scale well. Referring to one Suzuki Poulose review comment, his proposal
>>> to clear TRCOSLAR.OSLK early for all parts would mean one of these bools
>>> could go away. Otherwise, possibly add one (or more) bit definitions for
>>> use by the etm4_disable_arch_specific call. The order of this call would
>>> need to change, depending.
>>>
>>>>
>>>>> +       bool                            mmio_external;
>>>>>   };
>>>>>
>>>>>   /* Address comparator access types */
>>>>> --
>>>>> 2.25.1
>>>>>
>>>> Regards
>>>>
>>>> Mike
>>
>>
>>


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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Suzuki K Poulose]

Missed the reference, see below.

On 23/01/2023 22:18, Suzuki K Poulose wrote:
> On 23/01/2023 19:48, Steve Clevenger wrote:
>>
>>
>> On 1/23/2023 9:33 AM, Suzuki K Poulose wrote:
>>> On 23/01/2023 17:22, Steve Clevenger wrote:
>>>>
>>>>
>>>> On 1/23/2023 2:54 AM, Suzuki K Poulose wrote:
>>>>> On 21/01/2023 07:30, Steve Clevenger wrote:
>>>>>>
>>>>>> Hi Suzuki,
>>>>>>
>>>>>> Comments in-line. Please note the approach I attempted while 
>>>>>> adding in
>>>>>> the Ampere support was to otherwise not disturb existing driver code
>>>>>> for
>>>>>> non-Ampere parts.
>>>>>>
>>>>>> Steve
>>>>>>
>>>>>> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>>>>>>> Hi Steve
>>>>>>>
>>>>>>> Thanks for the patches. Have a few comments below.
>>>>>>>
>>>>>>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>>>>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1 
>>>>>>>> access.
>>>>>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>>>>>> Computing design decision MMIO reads are considered the same as an
>>>>>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>>>>>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>>>>>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>>>>>> (now deprecated) is supported.
>>>>>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>>>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>>>>
>>>>>>> Please could you add this erratum to the :
>>>>>>>
>>>>>>> Documentation/arm64/silicon-errata.rst ?
>>>>>>>
>>>>>>> Given the ETM is v4.6, doesn't it support system instructions and
>>>>>>> that is causing this issue of "MMIO access is considered external" ?
>>>>>>> If it does, I think we should drop all of this and simply wire the
>>>>>>> system instruction access support.
>>>>>
>>>>>> That's not the issue in this case. This MMIO access should've been
>>>>>> allowed by the Ampere ETMv4.6 implementation.  Based on comments I've
>>>>>
>>>>> That doesn't answe the question. Please could you confirm the value of
>>>>> ID_AA64DFR0_EL1 on your system ?
>>>> This ID_AA64DFR0_EL1 value came from a TRACE32 debug session connected
>>>> to this part. The ID_AA64DFR0_EL1 value is 0x000F01F210307619. So,
>>>> TraceVer, bits [7:4] are b0001. My understanding is the system register
>>>> interface must be implemented on all ETMv4.6 parts.
>>>
>>> So, I don't understand why we are pushing towards enabling the
>>> "obsolete" MMIO interface ? Is this because "ACPI" mandates it ?
>>> Then, please don't. The spec needs an update to reflect the ETMs
>>> with sysreg access and ETEs.
>>>
>>> Why not stick to the system register access* ?
>>>
>>> * PS: The ACPI support for the ETM/ETE needs additional changes to the
>>> CoreSight driver, *not* the CoreSight ACPI spec. @Anshuman is working on
>>> this at the moment and will be available soon.
>>>
>>> The hack patch below should be sufficient to give it a try and if it 
>>> works.
> 
>> I don't understand your postscript. Certainly there's driver work to be
>> done, but I also think the DEN0067 CoreSight ACPI specification needs
> 
> The issue is having a single HID for ETMs (which from a spec point of
> view makes sense for) with and without MMIO access. That brings two
> different components in Linux (AMBA hook for ACPI and a platform driver)
> compete for the said HID. There are other reasons to disconnect the
> CoreSight from AMBA framework and manage them directly [0].

[0] https://lkml.kernel.org/r/e37e12ab-9701-2883-724a-2a281ad35df2@arm.com



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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Steve Clevenger]

Hi Suzuki,

I've split out the bug fix (i.e. nr_addr_cmp use) to a separate patch
and added references to the Ampere erratum in silicon-errata.rst.
These will be submitted as separate patches.

The ETM4.x TRCOSLAR.OSLK early clear has moved to etm4_init_csdev_iomem
for all manufacturers. I think this is what you asked for.
The no_quad_mmio flag has moved to struct csdev_access, and the split
64-bit read/write logic has been implemented entirely in the header file
coresight-etm4x.h is the existing calls.
I'd like to retire this patch thread, and submit these as a new thread.
Is there an objection?

Thanks,
Steve

On 1/23/2023 2:51 PM, Suzuki K Poulose wrote:
> 
> Missed the reference, see below.
> 
> On 23/01/2023 22:18, Suzuki K Poulose wrote:
>> On 23/01/2023 19:48, Steve Clevenger wrote:
>>>
>>>
>>> On 1/23/2023 9:33 AM, Suzuki K Poulose wrote:
>>>> On 23/01/2023 17:22, Steve Clevenger wrote:
>>>>>
>>>>>
>>>>> On 1/23/2023 2:54 AM, Suzuki K Poulose wrote:
>>>>>> On 21/01/2023 07:30, Steve Clevenger wrote:
>>>>>>>
>>>>>>> Hi Suzuki,
>>>>>>>
>>>>>>> Comments in-line. Please note the approach I attempted while
>>>>>>> adding in
>>>>>>> the Ampere support was to otherwise not disturb existing driver code
>>>>>>> for
>>>>>>> non-Ampere parts.
>>>>>>>
>>>>>>> Steve
>>>>>>>
>>>>>>> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>>>>>>>> Hi Steve
>>>>>>>>
>>>>>>>> Thanks for the patches. Have a few comments below.
>>>>>>>>
>>>>>>>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>>>>>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1
>>>>>>>>> access.
>>>>>>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>>>>>>> Computing design decision MMIO reads are considered the same as an
>>>>>>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>>>>>>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>>>>>>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>>>>>>> (now deprecated) is supported.
>>>>>>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>>>>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>>>>>
>>>>>>>> Please could you add this erratum to the :
>>>>>>>>
>>>>>>>> Documentation/arm64/silicon-errata.rst ?
>>>>>>>>
>>>>>>>> Given the ETM is v4.6, doesn't it support system instructions and
>>>>>>>> that is causing this issue of "MMIO access is considered
>>>>>>>> external" ?
>>>>>>>> If it does, I think we should drop all of this and simply wire the
>>>>>>>> system instruction access support.
>>>>>>
>>>>>>> That's not the issue in this case. This MMIO access should've been
>>>>>>> allowed by the Ampere ETMv4.6 implementation.  Based on comments
>>>>>>> I've
>>>>>>
>>>>>> That doesn't answe the question. Please could you confirm the
>>>>>> value of
>>>>>> ID_AA64DFR0_EL1 on your system ?
>>>>> This ID_AA64DFR0_EL1 value came from a TRACE32 debug session connected
>>>>> to this part. The ID_AA64DFR0_EL1 value is 0x000F01F210307619. So,
>>>>> TraceVer, bits [7:4] are b0001. My understanding is the system
>>>>> register
>>>>> interface must be implemented on all ETMv4.6 parts.
>>>>
>>>> So, I don't understand why we are pushing towards enabling the
>>>> "obsolete" MMIO interface ? Is this because "ACPI" mandates it ?
>>>> Then, please don't. The spec needs an update to reflect the ETMs
>>>> with sysreg access and ETEs.
>>>>
>>>> Why not stick to the system register access* ?
>>>>
>>>> * PS: The ACPI support for the ETM/ETE needs additional changes to the
>>>> CoreSight driver, *not* the CoreSight ACPI spec. @Anshuman is
>>>> working on
>>>> this at the moment and will be available soon.
>>>>
>>>> The hack patch below should be sufficient to give it a try and if it
>>>> works.
>>
>>> I don't understand your postscript. Certainly there's driver work to be
>>> done, but I also think the DEN0067 CoreSight ACPI specification needs
>>
>> The issue is having a single HID for ETMs (which from a spec point of
>> view makes sense for) with and without MMIO access. That brings two
>> different components in Linux (AMBA hook for ACPI and a platform driver)
>> compete for the said HID. There are other reasons to disconnect the
>> CoreSight from AMBA framework and manage them directly [0].
> 
> [0] https://lkml.kernel.org/r/e37e12ab-9701-2883-724a-2a281ad35df2@arm.com
> 
> 

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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Suzuki K Poulose]

On 02/02/2023 05:20, Steve Clevenger wrote:
> 
> Hi Suzuki,
> 
> I've split out the bug fix (i.e. nr_addr_cmp use) to a separate patch

Thanks for that.

> and added references to the Ampere erratum in silicon-errata.rst.
> These will be submitted as separate patches.
> 
> The ETM4.x TRCOSLAR.OSLK early clear has moved to etm4_init_csdev_iomem
> for all manufacturers. I think this is what you asked for.
> The no_quad_mmio flag has moved to struct csdev_access, and the split
> 64-bit read/write logic has been implemented entirely in the header file
> coresight-etm4x.h is the existing calls.
> I'd like to retire this patch thread, and submit these as a new thread.
> Is there an objection?

I would still like to use the system instructions method for the ETM, 
than hacking the MMIO access for something that is obsolete.
The ACPI document for CoreSight will be published soon for review to
accommodate the description for ETMs without MMIO and it no longer
mandates the MemoryResource.

What is the objection to using system instruction access here ?

Thanks
Suzuki



> 
> Thanks,
> Steve
> 
> On 1/23/2023 2:51 PM, Suzuki K Poulose wrote:
>>
>> Missed the reference, see below.
>>
>> On 23/01/2023 22:18, Suzuki K Poulose wrote:
>>> On 23/01/2023 19:48, Steve Clevenger wrote:
>>>>
>>>>
>>>> On 1/23/2023 9:33 AM, Suzuki K Poulose wrote:
>>>>> On 23/01/2023 17:22, Steve Clevenger wrote:
>>>>>>
>>>>>>
>>>>>> On 1/23/2023 2:54 AM, Suzuki K Poulose wrote:
>>>>>>> On 21/01/2023 07:30, Steve Clevenger wrote:
>>>>>>>>
>>>>>>>> Hi Suzuki,
>>>>>>>>
>>>>>>>> Comments in-line. Please note the approach I attempted while
>>>>>>>> adding in
>>>>>>>> the Ampere support was to otherwise not disturb existing driver code
>>>>>>>> for
>>>>>>>> non-Ampere parts.
>>>>>>>>
>>>>>>>> Steve
>>>>>>>>
>>>>>>>> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>>>>>>>>> Hi Steve
>>>>>>>>>
>>>>>>>>> Thanks for the patches. Have a few comments below.
>>>>>>>>>
>>>>>>>>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>>>>>>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1
>>>>>>>>>> access.
>>>>>>>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>>>>>>>> Computing design decision MMIO reads are considered the same as an
>>>>>>>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1 access
>>>>>>>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1 read
>>>>>>>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>>>>>>>> (now deprecated) is supported.
>>>>>>>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>>>>>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>>>>>>
>>>>>>>>> Please could you add this erratum to the :
>>>>>>>>>
>>>>>>>>> Documentation/arm64/silicon-errata.rst ?
>>>>>>>>>
>>>>>>>>> Given the ETM is v4.6, doesn't it support system instructions and
>>>>>>>>> that is causing this issue of "MMIO access is considered
>>>>>>>>> external" ?
>>>>>>>>> If it does, I think we should drop all of this and simply wire the
>>>>>>>>> system instruction access support.
>>>>>>>
>>>>>>>> That's not the issue in this case. This MMIO access should've been
>>>>>>>> allowed by the Ampere ETMv4.6 implementation.  Based on comments
>>>>>>>> I've
>>>>>>>
>>>>>>> That doesn't answe the question. Please could you confirm the
>>>>>>> value of
>>>>>>> ID_AA64DFR0_EL1 on your system ?
>>>>>> This ID_AA64DFR0_EL1 value came from a TRACE32 debug session connected
>>>>>> to this part. The ID_AA64DFR0_EL1 value is 0x000F01F210307619. So,
>>>>>> TraceVer, bits [7:4] are b0001. My understanding is the system
>>>>>> register
>>>>>> interface must be implemented on all ETMv4.6 parts.
>>>>>
>>>>> So, I don't understand why we are pushing towards enabling the
>>>>> "obsolete" MMIO interface ? Is this because "ACPI" mandates it ?
>>>>> Then, please don't. The spec needs an update to reflect the ETMs
>>>>> with sysreg access and ETEs.
>>>>>
>>>>> Why not stick to the system register access* ?
>>>>>
>>>>> * PS: The ACPI support for the ETM/ETE needs additional changes to the
>>>>> CoreSight driver, *not* the CoreSight ACPI spec. @Anshuman is
>>>>> working on
>>>>> this at the moment and will be available soon.
>>>>>
>>>>> The hack patch below should be sufficient to give it a try and if it
>>>>> works.
>>>
>>>> I don't understand your postscript. Certainly there's driver work to be
>>>> done, but I also think the DEN0067 CoreSight ACPI specification needs
>>>
>>> The issue is having a single HID for ETMs (which from a spec point of
>>> view makes sense for) with and without MMIO access. That brings two
>>> different components in Linux (AMBA hook for ACPI and a platform driver)
>>> compete for the said HID. There are other reasons to disconnect the
>>> CoreSight from AMBA framework and manage them directly [0].
>>
>> [0] https://lkml.kernel.org/r/e37e12ab-9701-2883-724a-2a281ad35df2@arm.com
>>
>>


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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Steve Clevenger]

Hi Suzuki,

Commented in-line.

Steve C.

On 2/2/2023 3:16 AM, Suzuki K Poulose wrote:
> On 02/02/2023 05:20, Steve Clevenger wrote:
>>
>> Hi Suzuki,
>>
>> I've split out the bug fix (i.e. nr_addr_cmp use) to a separate patch
> 
> Thanks for that.
> 
>> and added references to the Ampere erratum in silicon-errata.rst.
>> These will be submitted as separate patches.
>>
>> The ETM4.x TRCOSLAR.OSLK early clear has moved to etm4_init_csdev_iomem
>> for all manufacturers. I think this is what you asked for.
>> The no_quad_mmio flag has moved to struct csdev_access, and the split
>> 64-bit read/write logic has been implemented entirely in the header file
>> coresight-etm4x.h is the existing calls.
>> I'd like to retire this patch thread, and submit these as a new thread.
>> Is there an objection?
> 
> I would still like to use the system instructions method for the ETM,
> than hacking the MMIO access for something that is obsolete.
> The ACPI document for CoreSight will be published soon for review to
> accommodate the description for ETMs without MMIO and it no longer
> mandates the MemoryResource.
> 
> What is the objection to using system instruction access here ?
No objection going forward. For our initial release, we're not in a
position to change the CoreSight DSDT based on a specification which is
incomplete.
Based on a quick sysreg only build, I didn't collect trace samples. I
haven't had time to chase this, but the reported error is "timeout while
waiting for Trace Idle Status" on a TRCSTATR read. More testing is
required. If this isn't related to an Ampere sysreg access problem
(doubtful), the next place I'd look is as a synchronization issue.

> 
> Thanks
> Suzuki
> 
> 
> 
>>
>> Thanks,
>> Steve
>>
>> On 1/23/2023 2:51 PM, Suzuki K Poulose wrote:
>>>
>>> Missed the reference, see below.
>>>
>>> On 23/01/2023 22:18, Suzuki K Poulose wrote:
>>>> On 23/01/2023 19:48, Steve Clevenger wrote:
>>>>>
>>>>>
>>>>> On 1/23/2023 9:33 AM, Suzuki K Poulose wrote:
>>>>>> On 23/01/2023 17:22, Steve Clevenger wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 1/23/2023 2:54 AM, Suzuki K Poulose wrote:
>>>>>>>> On 21/01/2023 07:30, Steve Clevenger wrote:
>>>>>>>>>
>>>>>>>>> Hi Suzuki,
>>>>>>>>>
>>>>>>>>> Comments in-line. Please note the approach I attempted while
>>>>>>>>> adding in
>>>>>>>>> the Ampere support was to otherwise not disturb existing driver
>>>>>>>>> code
>>>>>>>>> for
>>>>>>>>> non-Ampere parts.
>>>>>>>>>
>>>>>>>>> Steve
>>>>>>>>>
>>>>>>>>> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>>>>>>>>>> Hi Steve
>>>>>>>>>>
>>>>>>>>>> Thanks for the patches. Have a few comments below.
>>>>>>>>>>
>>>>>>>>>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>>>>>>>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1
>>>>>>>>>>> access.
>>>>>>>>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>>>>>>>>> Computing design decision MMIO reads are considered the same
>>>>>>>>>>> as an
>>>>>>>>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1
>>>>>>>>>>> access
>>>>>>>>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1
>>>>>>>>>>> read
>>>>>>>>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>>>>>>>>> (now deprecated) is supported.
>>>>>>>>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>>>>>>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>>>>>>>
>>>>>>>>>> Please could you add this erratum to the :
>>>>>>>>>>
>>>>>>>>>> Documentation/arm64/silicon-errata.rst ?
>>>>>>>>>>
>>>>>>>>>> Given the ETM is v4.6, doesn't it support system instructions and
>>>>>>>>>> that is causing this issue of "MMIO access is considered
>>>>>>>>>> external" ?
>>>>>>>>>> If it does, I think we should drop all of this and simply wire
>>>>>>>>>> the
>>>>>>>>>> system instruction access support.
>>>>>>>>
>>>>>>>>> That's not the issue in this case. This MMIO access should've been
>>>>>>>>> allowed by the Ampere ETMv4.6 implementation.  Based on comments
>>>>>>>>> I've
>>>>>>>>
>>>>>>>> That doesn't answe the question. Please could you confirm the
>>>>>>>> value of
>>>>>>>> ID_AA64DFR0_EL1 on your system ?
>>>>>>> This ID_AA64DFR0_EL1 value came from a TRACE32 debug session
>>>>>>> connected
>>>>>>> to this part. The ID_AA64DFR0_EL1 value is 0x000F01F210307619. So,
>>>>>>> TraceVer, bits [7:4] are b0001. My understanding is the system
>>>>>>> register
>>>>>>> interface must be implemented on all ETMv4.6 parts.
>>>>>>
>>>>>> So, I don't understand why we are pushing towards enabling the
>>>>>> "obsolete" MMIO interface ? Is this because "ACPI" mandates it ?
>>>>>> Then, please don't. The spec needs an update to reflect the ETMs
>>>>>> with sysreg access and ETEs.
>>>>>>
>>>>>> Why not stick to the system register access* ?
>>>>>>
>>>>>> * PS: The ACPI support for the ETM/ETE needs additional changes to
>>>>>> the
>>>>>> CoreSight driver, *not* the CoreSight ACPI spec. @Anshuman is
>>>>>> working on
>>>>>> this at the moment and will be available soon.
>>>>>>
>>>>>> The hack patch below should be sufficient to give it a try and if it
>>>>>> works.
>>>>
>>>>> I don't understand your postscript. Certainly there's driver work
>>>>> to be
>>>>> done, but I also think the DEN0067 CoreSight ACPI specification needs
>>>>
>>>> The issue is having a single HID for ETMs (which from a spec point of
>>>> view makes sense for) with and without MMIO access. That brings two
>>>> different components in Linux (AMBA hook for ACPI and a platform
>>>> driver)
>>>> compete for the said HID. There are other reasons to disconnect the
>>>> CoreSight from AMBA framework and manage them directly [0].
>>>
>>> [0]
>>> https://lkml.kernel.org/r/e37e12ab-9701-2883-724a-2a281ad35df2@arm.com
>>>
>>>
> 

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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Suzuki K Poulose]

On 02/02/2023 17:12, Steve Clevenger wrote:
> Hi Suzuki,
> 
> Commented in-line.
> 
> Steve C.
> 
> On 2/2/2023 3:16 AM, Suzuki K Poulose wrote:
>> On 02/02/2023 05:20, Steve Clevenger wrote:
>>>
>>> Hi Suzuki,
>>>
>>> I've split out the bug fix (i.e. nr_addr_cmp use) to a separate patch
>>
>> Thanks for that.
>>
>>> and added references to the Ampere erratum in silicon-errata.rst.
>>> These will be submitted as separate patches.
>>>
>>> The ETM4.x TRCOSLAR.OSLK early clear has moved to etm4_init_csdev_iomem
>>> for all manufacturers. I think this is what you asked for.
>>> The no_quad_mmio flag has moved to struct csdev_access, and the split
>>> 64-bit read/write logic has been implemented entirely in the header file
>>> coresight-etm4x.h is the existing calls.
>>> I'd like to retire this patch thread, and submit these as a new thread.
>>> Is there an objection?
>>
>> I would still like to use the system instructions method for the ETM,
>> than hacking the MMIO access for something that is obsolete.
>> The ACPI document for CoreSight will be published soon for review to
>> accommodate the description for ETMs without MMIO and it no longer
>> mandates the MemoryResource.
>>
>> What is the objection to using system instruction access here ?
> No objection going forward. For our initial release, we're not in a
> position to change the CoreSight DSDT based on a specification which is
> incomplete.

There is on change to the CoreSight DSDT specification as such. The only
change to the "spec" is along the lines of :

"MMIO interface is mandatory only if not accessible via system 
instruction access "


> Based on a quick sysreg only build, I didn't collect trace samples. I
> haven't had time to chase this, but the reported error is "timeout while
> waiting for Trace Idle Status" on a TRCSTATR read. More testing is

Are you able to access the other registers ?

e.g,

$ cat /sys/bus/coresight/devices/etm0/mgmt/trcpidr0

Suzuki


> required. If this isn't related to an Ampere sysreg access problem
> (doubtful), the next place I'd look is as a synchronization issue.
> 
>>
>> Thanks
>> Suzuki
>>
>>
>>
>>>
>>> Thanks,
>>> Steve
>>>
>>> On 1/23/2023 2:51 PM, Suzuki K Poulose wrote:
>>>>
>>>> Missed the reference, see below.
>>>>
>>>> On 23/01/2023 22:18, Suzuki K Poulose wrote:
>>>>> On 23/01/2023 19:48, Steve Clevenger wrote:
>>>>>>
>>>>>>
>>>>>> On 1/23/2023 9:33 AM, Suzuki K Poulose wrote:
>>>>>>> On 23/01/2023 17:22, Steve Clevenger wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> On 1/23/2023 2:54 AM, Suzuki K Poulose wrote:
>>>>>>>>> On 21/01/2023 07:30, Steve Clevenger wrote:
>>>>>>>>>>
>>>>>>>>>> Hi Suzuki,
>>>>>>>>>>
>>>>>>>>>> Comments in-line. Please note the approach I attempted while
>>>>>>>>>> adding in
>>>>>>>>>> the Ampere support was to otherwise not disturb existing driver
>>>>>>>>>> code
>>>>>>>>>> for
>>>>>>>>>> non-Ampere parts.
>>>>>>>>>>
>>>>>>>>>> Steve
>>>>>>>>>>
>>>>>>>>>> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>>>>>>>>>>> Hi Steve
>>>>>>>>>>>
>>>>>>>>>>> Thanks for the patches. Have a few comments below.
>>>>>>>>>>>
>>>>>>>>>>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>>>>>>>>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1
>>>>>>>>>>>> access.
>>>>>>>>>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>>>>>>>>>> Computing design decision MMIO reads are considered the same
>>>>>>>>>>>> as an
>>>>>>>>>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1
>>>>>>>>>>>> access
>>>>>>>>>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1
>>>>>>>>>>>> read
>>>>>>>>>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>>>>>>>>>> (now deprecated) is supported.
>>>>>>>>>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>>>>>>>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>>>>>>>>
>>>>>>>>>>> Please could you add this erratum to the :
>>>>>>>>>>>
>>>>>>>>>>> Documentation/arm64/silicon-errata.rst ?
>>>>>>>>>>>
>>>>>>>>>>> Given the ETM is v4.6, doesn't it support system instructions and
>>>>>>>>>>> that is causing this issue of "MMIO access is considered
>>>>>>>>>>> external" ?
>>>>>>>>>>> If it does, I think we should drop all of this and simply wire
>>>>>>>>>>> the
>>>>>>>>>>> system instruction access support.
>>>>>>>>>
>>>>>>>>>> That's not the issue in this case. This MMIO access should've been
>>>>>>>>>> allowed by the Ampere ETMv4.6 implementation.  Based on comments
>>>>>>>>>> I've
>>>>>>>>>
>>>>>>>>> That doesn't answe the question. Please could you confirm the
>>>>>>>>> value of
>>>>>>>>> ID_AA64DFR0_EL1 on your system ?
>>>>>>>> This ID_AA64DFR0_EL1 value came from a TRACE32 debug session
>>>>>>>> connected
>>>>>>>> to this part. The ID_AA64DFR0_EL1 value is 0x000F01F210307619. So,
>>>>>>>> TraceVer, bits [7:4] are b0001. My understanding is the system
>>>>>>>> register
>>>>>>>> interface must be implemented on all ETMv4.6 parts.
>>>>>>>
>>>>>>> So, I don't understand why we are pushing towards enabling the
>>>>>>> "obsolete" MMIO interface ? Is this because "ACPI" mandates it ?
>>>>>>> Then, please don't. The spec needs an update to reflect the ETMs
>>>>>>> with sysreg access and ETEs.
>>>>>>>
>>>>>>> Why not stick to the system register access* ?
>>>>>>>
>>>>>>> * PS: The ACPI support for the ETM/ETE needs additional changes to
>>>>>>> the
>>>>>>> CoreSight driver, *not* the CoreSight ACPI spec. @Anshuman is
>>>>>>> working on
>>>>>>> this at the moment and will be available soon.
>>>>>>>
>>>>>>> The hack patch below should be sufficient to give it a try and if it
>>>>>>> works.
>>>>>
>>>>>> I don't understand your postscript. Certainly there's driver work
>>>>>> to be
>>>>>> done, but I also think the DEN0067 CoreSight ACPI specification needs
>>>>>
>>>>> The issue is having a single HID for ETMs (which from a spec point of
>>>>> view makes sense for) with and without MMIO access. That brings two
>>>>> different components in Linux (AMBA hook for ACPI and a platform
>>>>> driver)
>>>>> compete for the said HID. There are other reasons to disconnect the
>>>>> CoreSight from AMBA framework and manage them directly [0].
>>>>
>>>> [0]
>>>> https://lkml.kernel.org/r/e37e12ab-9701-2883-724a-2a281ad35df2@arm.com
>>>>
>>>>
>>


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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Steve Clevenger]

On 2/2/2023 9:27 AM, Suzuki K Poulose wrote:
> On 02/02/2023 17:12, Steve Clevenger wrote:
>> Hi Suzuki,
>>
>> Commented in-line.
>>
>> Steve C.
>>
>> On 2/2/2023 3:16 AM, Suzuki K Poulose wrote:
>>> On 02/02/2023 05:20, Steve Clevenger wrote:
>>>>
>>>> Hi Suzuki,
>>>>
>>>> I've split out the bug fix (i.e. nr_addr_cmp use) to a separate patch
>>>
>>> Thanks for that.
>>>
>>>> and added references to the Ampere erratum in silicon-errata.rst.
>>>> These will be submitted as separate patches.
>>>>
>>>> The ETM4.x TRCOSLAR.OSLK early clear has moved to etm4_init_csdev_iomem
>>>> for all manufacturers. I think this is what you asked for.
>>>> The no_quad_mmio flag has moved to struct csdev_access, and the split
>>>> 64-bit read/write logic has been implemented entirely in the header
>>>> file
>>>> coresight-etm4x.h is the existing calls.
>>>> I'd like to retire this patch thread, and submit these as a new thread.
>>>> Is there an objection?
>>>
>>> I would still like to use the system instructions method for the ETM,
>>> than hacking the MMIO access for something that is obsolete.
>>> The ACPI document for CoreSight will be published soon for review to
>>> accommodate the description for ETMs without MMIO and it no longer
>>> mandates the MemoryResource.
>>>
>>> What is the objection to using system instruction access here ?
>> No objection going forward. For our initial release, we're not in a
>> position to change the CoreSight DSDT based on a specification which is
>> incomplete.
> 
> There is on change to the CoreSight DSDT specification as such. The only
> change to the "spec" is along the lines of :
> 
> "MMIO interface is mandatory only if not accessible via system
> instruction access "
> 
> 
>> Based on a quick sysreg only build, I didn't collect trace samples. I
>> haven't had time to chase this, but the reported error is "timeout while
>> waiting for Trace Idle Status" on a TRCSTATR read. More testing is
> 
> Are you able to access the other registers ?
> 
> e.g,
> 
> $ cat /sys/bus/coresight/devices/etm0/mgmt/trcpidr0
> 
I'll need to determine which of the 3 coresight_timeout calls which read
the TRCSTATR idle bit times out. In each case a number of sysreg
accesses have occurred prior to any of these 3 calls.

> Suzuki
> 
> 
>> required. If this isn't related to an Ampere sysreg access problem
>> (doubtful), the next place I'd look is as a synchronization issue.
>>
>>>
>>> Thanks
>>> Suzuki
>>>
>>>
>>>
>>>>
>>>> Thanks,
>>>> Steve
>>>>
>>>> On 1/23/2023 2:51 PM, Suzuki K Poulose wrote:
>>>>>
>>>>> Missed the reference, see below.
>>>>>
>>>>> On 23/01/2023 22:18, Suzuki K Poulose wrote:
>>>>>> On 23/01/2023 19:48, Steve Clevenger wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 1/23/2023 9:33 AM, Suzuki K Poulose wrote:
>>>>>>>> On 23/01/2023 17:22, Steve Clevenger wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 1/23/2023 2:54 AM, Suzuki K Poulose wrote:
>>>>>>>>>> On 21/01/2023 07:30, Steve Clevenger wrote:
>>>>>>>>>>>
>>>>>>>>>>> Hi Suzuki,
>>>>>>>>>>>
>>>>>>>>>>> Comments in-line. Please note the approach I attempted while
>>>>>>>>>>> adding in
>>>>>>>>>>> the Ampere support was to otherwise not disturb existing driver
>>>>>>>>>>> code
>>>>>>>>>>> for
>>>>>>>>>>> non-Ampere parts.
>>>>>>>>>>>
>>>>>>>>>>> Steve
>>>>>>>>>>>
>>>>>>>>>>> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>>>>>>>>>>>> Hi Steve
>>>>>>>>>>>>
>>>>>>>>>>>> Thanks for the patches. Have a few comments below.
>>>>>>>>>>>>
>>>>>>>>>>>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>>>>>>>>>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1
>>>>>>>>>>>>> access.
>>>>>>>>>>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>>>>>>>>>>> Computing design decision MMIO reads are considered the same
>>>>>>>>>>>>> as an
>>>>>>>>>>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1
>>>>>>>>>>>>> access
>>>>>>>>>>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1
>>>>>>>>>>>>> read
>>>>>>>>>>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>>>>>>>>>>> (now deprecated) is supported.
>>>>>>>>>>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>>>>>>>>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>>>>>>>>>
>>>>>>>>>>>> Please could you add this erratum to the :
>>>>>>>>>>>>
>>>>>>>>>>>> Documentation/arm64/silicon-errata.rst ?
>>>>>>>>>>>>
>>>>>>>>>>>> Given the ETM is v4.6, doesn't it support system
>>>>>>>>>>>> instructions and
>>>>>>>>>>>> that is causing this issue of "MMIO access is considered
>>>>>>>>>>>> external" ?
>>>>>>>>>>>> If it does, I think we should drop all of this and simply wire
>>>>>>>>>>>> the
>>>>>>>>>>>> system instruction access support.
>>>>>>>>>>
>>>>>>>>>>> That's not the issue in this case. This MMIO access should've
>>>>>>>>>>> been
>>>>>>>>>>> allowed by the Ampere ETMv4.6 implementation.  Based on comments
>>>>>>>>>>> I've
>>>>>>>>>>
>>>>>>>>>> That doesn't answe the question. Please could you confirm the
>>>>>>>>>> value of
>>>>>>>>>> ID_AA64DFR0_EL1 on your system ?
>>>>>>>>> This ID_AA64DFR0_EL1 value came from a TRACE32 debug session
>>>>>>>>> connected
>>>>>>>>> to this part. The ID_AA64DFR0_EL1 value is 0x000F01F210307619. So,
>>>>>>>>> TraceVer, bits [7:4] are b0001. My understanding is the system
>>>>>>>>> register
>>>>>>>>> interface must be implemented on all ETMv4.6 parts.
>>>>>>>>
>>>>>>>> So, I don't understand why we are pushing towards enabling the
>>>>>>>> "obsolete" MMIO interface ? Is this because "ACPI" mandates it ?
>>>>>>>> Then, please don't. The spec needs an update to reflect the ETMs
>>>>>>>> with sysreg access and ETEs.
>>>>>>>>
>>>>>>>> Why not stick to the system register access* ?
>>>>>>>>
>>>>>>>> * PS: The ACPI support for the ETM/ETE needs additional changes to
>>>>>>>> the
>>>>>>>> CoreSight driver, *not* the CoreSight ACPI spec. @Anshuman is
>>>>>>>> working on
>>>>>>>> this at the moment and will be available soon.
>>>>>>>>
>>>>>>>> The hack patch below should be sufficient to give it a try and
>>>>>>>> if it
>>>>>>>> works.
>>>>>>
>>>>>>> I don't understand your postscript. Certainly there's driver work
>>>>>>> to be
>>>>>>> done, but I also think the DEN0067 CoreSight ACPI specification
>>>>>>> needs
>>>>>>
>>>>>> The issue is having a single HID for ETMs (which from a spec point of
>>>>>> view makes sense for) with and without MMIO access. That brings two
>>>>>> different components in Linux (AMBA hook for ACPI and a platform
>>>>>> driver)
>>>>>> compete for the said HID. There are other reasons to disconnect the
>>>>>> CoreSight from AMBA framework and manage them directly [0].
>>>>>
>>>>> [0]
>>>>> https://lkml.kernel.org/r/e37e12ab-9701-2883-724a-2a281ad35df2@arm.com
>>>>>
>>>>>
>>>
> 

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Re: [PATCH 1/3] coresight etm4x: Early clear TRCOSLAR.OSLK prior to TRCIDR1 read

[Suzuki K Poulose]

Hi Steve

fyi, the ACPI spec for CoreSight has been updated to relax the
MMIO region requirement for ETMv4x and ETE. Please find it here :

https://developer.arm.com/documentation/den0067/latest


Kind regards
Suzuki


On 02/02/2023 23:03, Steve Clevenger wrote:
> 
> 
> On 2/2/2023 9:27 AM, Suzuki K Poulose wrote:
>> On 02/02/2023 17:12, Steve Clevenger wrote:
>>> Hi Suzuki,
>>>
>>> Commented in-line.
>>>
>>> Steve C.
>>>
>>> On 2/2/2023 3:16 AM, Suzuki K Poulose wrote:
>>>> On 02/02/2023 05:20, Steve Clevenger wrote:
>>>>>
>>>>> Hi Suzuki,
>>>>>
>>>>> I've split out the bug fix (i.e. nr_addr_cmp use) to a separate patch
>>>>
>>>> Thanks for that.
>>>>
>>>>> and added references to the Ampere erratum in silicon-errata.rst.
>>>>> These will be submitted as separate patches.
>>>>>
>>>>> The ETM4.x TRCOSLAR.OSLK early clear has moved to etm4_init_csdev_iomem
>>>>> for all manufacturers. I think this is what you asked for.
>>>>> The no_quad_mmio flag has moved to struct csdev_access, and the split
>>>>> 64-bit read/write logic has been implemented entirely in the header
>>>>> file
>>>>> coresight-etm4x.h is the existing calls.
>>>>> I'd like to retire this patch thread, and submit these as a new thread.
>>>>> Is there an objection?
>>>>
>>>> I would still like to use the system instructions method for the ETM,
>>>> than hacking the MMIO access for something that is obsolete.
>>>> The ACPI document for CoreSight will be published soon for review to
>>>> accommodate the description for ETMs without MMIO and it no longer
>>>> mandates the MemoryResource.
>>>>
>>>> What is the objection to using system instruction access here ?
>>> No objection going forward. For our initial release, we're not in a
>>> position to change the CoreSight DSDT based on a specification which is
>>> incomplete.
>>
>> There is on change to the CoreSight DSDT specification as such. The only
>> change to the "spec" is along the lines of :
>>
>> "MMIO interface is mandatory only if not accessible via system
>> instruction access "
>>
>>
>>> Based on a quick sysreg only build, I didn't collect trace samples. I
>>> haven't had time to chase this, but the reported error is "timeout while
>>> waiting for Trace Idle Status" on a TRCSTATR read. More testing is
>>
>> Are you able to access the other registers ?
>>
>> e.g,
>>
>> $ cat /sys/bus/coresight/devices/etm0/mgmt/trcpidr0
>>
> I'll need to determine which of the 3 coresight_timeout calls which read
> the TRCSTATR idle bit times out. In each case a number of sysreg
> accesses have occurred prior to any of these 3 calls.
> 
>> Suzuki
>>
>>
>>> required. If this isn't related to an Ampere sysreg access problem
>>> (doubtful), the next place I'd look is as a synchronization issue.
>>>
>>>>
>>>> Thanks
>>>> Suzuki
>>>>
>>>>
>>>>
>>>>>
>>>>> Thanks,
>>>>> Steve
>>>>>
>>>>> On 1/23/2023 2:51 PM, Suzuki K Poulose wrote:
>>>>>>
>>>>>> Missed the reference, see below.
>>>>>>
>>>>>> On 23/01/2023 22:18, Suzuki K Poulose wrote:
>>>>>>> On 23/01/2023 19:48, Steve Clevenger wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> On 1/23/2023 9:33 AM, Suzuki K Poulose wrote:
>>>>>>>>> On 23/01/2023 17:22, Steve Clevenger wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 1/23/2023 2:54 AM, Suzuki K Poulose wrote:
>>>>>>>>>>> On 21/01/2023 07:30, Steve Clevenger wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> Hi Suzuki,
>>>>>>>>>>>>
>>>>>>>>>>>> Comments in-line. Please note the approach I attempted while
>>>>>>>>>>>> adding in
>>>>>>>>>>>> the Ampere support was to otherwise not disturb existing driver
>>>>>>>>>>>> code
>>>>>>>>>>>> for
>>>>>>>>>>>> non-Ampere parts.
>>>>>>>>>>>>
>>>>>>>>>>>> Steve
>>>>>>>>>>>>
>>>>>>>>>>>> On 1/20/2023 3:12 AM, Suzuki K Poulose wrote:
>>>>>>>>>>>>> Hi Steve
>>>>>>>>>>>>>
>>>>>>>>>>>>> Thanks for the patches. Have a few comments below.
>>>>>>>>>>>>>
>>>>>>>>>>>>> On 20/01/2023 00:51, Steve Clevenger wrote:
>>>>>>>>>>>>>> Add Ampere early clear of ETM TRCOSLAR.OSLK prior to TRCIDR1
>>>>>>>>>>>>>> access.
>>>>>>>>>>>>>> Ampere Computing erratum AC03_DEBUG_06 describes an Ampere
>>>>>>>>>>>>>> Computing design decision MMIO reads are considered the same
>>>>>>>>>>>>>> as an
>>>>>>>>>>>>>> external debug access. If TRCOSLAR.OSLK is set, the TRCIDR1
>>>>>>>>>>>>>> access
>>>>>>>>>>>>>> results in a bus fault followed by a kernel panic.  A TRCIDR1
>>>>>>>>>>>>>> read
>>>>>>>>>>>>>> is valid regardless of TRCOSLAR.OSLK provided MMIO access
>>>>>>>>>>>>>> (now deprecated) is supported.
>>>>>>>>>>>>>> AC03_DEBUG_06 is described in the AmpereOne Developer Errata:
>>>>>>>>>>>>>> https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation
>>>>>>>>>>>>>
>>>>>>>>>>>>> Please could you add this erratum to the :
>>>>>>>>>>>>>
>>>>>>>>>>>>> Documentation/arm64/silicon-errata.rst ?
>>>>>>>>>>>>>
>>>>>>>>>>>>> Given the ETM is v4.6, doesn't it support system
>>>>>>>>>>>>> instructions and
>>>>>>>>>>>>> that is causing this issue of "MMIO access is considered
>>>>>>>>>>>>> external" ?
>>>>>>>>>>>>> If it does, I think we should drop all of this and simply wire
>>>>>>>>>>>>> the
>>>>>>>>>>>>> system instruction access support.
>>>>>>>>>>>
>>>>>>>>>>>> That's not the issue in this case. This MMIO access should've
>>>>>>>>>>>> been
>>>>>>>>>>>> allowed by the Ampere ETMv4.6 implementation.  Based on comments
>>>>>>>>>>>> I've
>>>>>>>>>>>
>>>>>>>>>>> That doesn't answe the question. Please could you confirm the
>>>>>>>>>>> value of
>>>>>>>>>>> ID_AA64DFR0_EL1 on your system ?
>>>>>>>>>> This ID_AA64DFR0_EL1 value came from a TRACE32 debug session
>>>>>>>>>> connected
>>>>>>>>>> to this part. The ID_AA64DFR0_EL1 value is 0x000F01F210307619. So,
>>>>>>>>>> TraceVer, bits [7:4] are b0001. My understanding is the system
>>>>>>>>>> register
>>>>>>>>>> interface must be implemented on all ETMv4.6 parts.
>>>>>>>>>
>>>>>>>>> So, I don't understand why we are pushing towards enabling the
>>>>>>>>> "obsolete" MMIO interface ? Is this because "ACPI" mandates it ?
>>>>>>>>> Then, please don't. The spec needs an update to reflect the ETMs
>>>>>>>>> with sysreg access and ETEs.
>>>>>>>>>
>>>>>>>>> Why not stick to the system register access* ?
>>>>>>>>>
>>>>>>>>> * PS: The ACPI support for the ETM/ETE needs additional changes to
>>>>>>>>> the
>>>>>>>>> CoreSight driver, *not* the CoreSight ACPI spec. @Anshuman is
>>>>>>>>> working on
>>>>>>>>> this at the moment and will be available soon.
>>>>>>>>>
>>>>>>>>> The hack patch below should be sufficient to give it a try and
>>>>>>>>> if it
>>>>>>>>> works.
>>>>>>>
>>>>>>>> I don't understand your postscript. Certainly there's driver work
>>>>>>>> to be
>>>>>>>> done, but I also think the DEN0067 CoreSight ACPI specification
>>>>>>>> needs
>>>>>>>
>>>>>>> The issue is having a single HID for ETMs (which from a spec point of
>>>>>>> view makes sense for) with and without MMIO access. That brings two
>>>>>>> different components in Linux (AMBA hook for ACPI and a platform
>>>>>>> driver)
>>>>>>> compete for the said HID. There are other reasons to disconnect the
>>>>>>> CoreSight from AMBA framework and manage them directly [0].
>>>>>>
>>>>>> [0]
>>>>>> https://lkml.kernel.org/r/e37e12ab-9701-2883-724a-2a281ad35df2@arm.com
>>>>>>
>>>>>>
>>>>
>>


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Re: [PATCH 2/3] coresight etm4x: Add 32-bit read/write option to split 64-bit words

[James Clark]

On 20/01/2023 11:19, Suzuki K Poulose wrote:
> On 20/01/2023 00:51, Steve Clevenger wrote:
[...]
>>       }
>> -    for (i = 0; i < drvdata->nr_addr_cmp; i++) {
>> -        etm4x_relaxed_write64(csa, config->addr_val[i], TRCACVRn(i));
>> -        etm4x_relaxed_write64(csa, config->addr_acc[i], TRCACATRn(i));
>> +    for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
>> +        if (drvdata->no_quad_mmio) {
>> +            etm4x_split_write64(csa, config->addr_val[i], TRCACVRn(i));
>> +            etm4x_split_write64(csa, config->addr_acc[i], TRCACATRn(i));
>> +        } else {
>> +            etm4x_relaxed_write64(csa, config->addr_val[i],
>> TRCACVRn(i));
>> +            etm4x_relaxed_write64(csa, config->addr_acc[i],
>> TRCACATRn(i));
>> +        }
>> +    }
> 
> Something like this can be leave some places out. I think we could hide
> it under the generic helpers and handle it there. May be "struct
> csdev_access" can cache this "no_quad_mmio" and do the right thing ?

+1 for this, or just pass drvdata to etm4x_relaxed_write64() and then it
can decide what to do. I'd prefer that to caching the value in
csdev_access because it would just be a copy of some other value and
might go stale or not be set at some point.

James

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Re: [PATCH 2/3] coresight etm4x: Add 32-bit read/write option to split 64-bit words

[Steve Clevenger]

Hi James,

Thanks for the feedback. I did hide the split 64-bit implementation
under the generic helpers. Note these helpers are now static inline code
instead of macro implementations. This significantly reduced the number
of changes where the etm4x_relaxed write64 and etm4x_relaxed_read64
calls were used.

Steve

On 3/6/2023 2:37 AM, James Clark wrote:
> 
> 
> On 20/01/2023 11:19, Suzuki K Poulose wrote:
>> On 20/01/2023 00:51, Steve Clevenger wrote:
> [...]
>>>       }
>>> -    for (i = 0; i < drvdata->nr_addr_cmp; i++) {
>>> -        etm4x_relaxed_write64(csa, config->addr_val[i], TRCACVRn(i));
>>> -        etm4x_relaxed_write64(csa, config->addr_acc[i], TRCACATRn(i));
>>> +    for (i = 0; i < drvdata->nr_addr_cmp * 2; i++) {
>>> +        if (drvdata->no_quad_mmio) {
>>> +            etm4x_split_write64(csa, config->addr_val[i], TRCACVRn(i));
>>> +            etm4x_split_write64(csa, config->addr_acc[i], TRCACATRn(i));
>>> +        } else {
>>> +            etm4x_relaxed_write64(csa, config->addr_val[i],
>>> TRCACVRn(i));
>>> +            etm4x_relaxed_write64(csa, config->addr_acc[i],
>>> TRCACATRn(i));
>>> +        }
>>> +    }
>>
>> Something like this can be leave some places out. I think we could hide
>> it under the generic helpers and handle it there. May be "struct
>> csdev_access" can cache this "no_quad_mmio" and do the right thing ?
> 
> +1 for this, or just pass drvdata to etm4x_relaxed_write64() and then it
> can decide what to do. I'd prefer that to caching the value in
> csdev_access because it would just be a copy of some other value and
> might go stale or not be set at some point.
> 
> James

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