[PATCH 1/2] powerpc/perf: Infrastructure to support checking of attr.config*

Introduce code to support the checking of attr.config* for
values which are reserved for a given platform.
Performance Monitoring Unit (PMU) configuration registers
have fileds that are reserved and specific values to bit fields
as reserved. Writing a none zero values in these fields
or writing invalid value to bit fields will have unknown
behaviours.

Patch here add a generic call-back function "check_attr_config"
in "struct power_pmu", to be called in event_init to
check for attr.config* values for a given platform.
"check_attr_config" is valid only for raw event type.

Suggested-by: Alexey Kardashevskiy <redacted>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
---
 arch/powerpc/include/asm/perf_event_server.h |  6 ++++++
 arch/powerpc/perf/core-book3s.c              | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/arch/powerpc/include/asm/perf_event_server.h b/arch/powerpc/include/asm/perf_event_server.h
index 00e7e671bb4b..dde97d7d9253 100644
--- a/arch/powerpc/include/asm/perf_event_server.h
+++ b/arch/powerpc/include/asm/perf_event_server.h

@@ -67,6 +67,12 @@ struct power_pmu {
 	 * the pmu supports extended perf regs capability
 	 */
 	int		capabilities;
+	/*
+	 * Function to check event code for values which are
+	 * reserved. Function takes struct perf_event as input,
+	 * since event code could be spread in attr.config*
+	 */
+	int		(*check_attr_config)(struct perf_event *ev);
 };
 
 /*

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 6817331e22ff..679d67506299 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c

@@ -1958,6 +1958,18 @@ static int power_pmu_event_init(struct perf_event *event)
 
 		if (ppmu->blacklist_ev && is_event_blacklisted(ev))
 			return -EINVAL;
+		/*
+		 * PMU config registers have fileds that are
+		 * reserved and spacific values to bit fileds be reserved.
+		 * This call-back will check the event code for same.
+		 *
+		 * Event type hardware and hw_cache will not value
+		 * invalid values in the event code which is not true
+		 * for raw event type.
+		 */
+		if (ppmu->check_attr_config &&
+		    ppmu->check_attr_config(event))
+			return -EINVAL;
 		break;
 	default:
 		return -ENOENT;

-- 
2.26.2

Add platform specific attr.config value checks. Patch
includes checks for power9 and power10 platforms.

Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
---
 arch/powerpc/perf/isa207-common.c | 41 +++++++++++++++++++++++++++++++
 arch/powerpc/perf/isa207-common.h |  2 ++
 arch/powerpc/perf/power10-pmu.c   | 13 ++++++++++
 arch/powerpc/perf/power9-pmu.c    | 13 ++++++++++
 4 files changed, 69 insertions(+)

diff --git a/arch/powerpc/perf/isa207-common.c b/arch/powerpc/perf/isa207-common.c
index e4f577da33d8..b255799f5b51 100644
--- a/arch/powerpc/perf/isa207-common.c
+++ b/arch/powerpc/perf/isa207-common.c

@@ -694,3 +694,44 @@ int isa207_get_alternatives(u64 event, u64 alt[], int size, unsigned int flags,
 
 	return num_alt;
 }
+
+int isa3_X_check_attr_config(struct perf_event *ev)
+{
+	u64 val, sample_mode;
+	u64 event = ev->attr.config;
+
+	val = (event >> EVENT_SAMPLE_SHIFT) & EVENT_SAMPLE_MASK;
+	sample_mode = val & 0x3;
+
+	/*
+	 * MMCRA[61:62] is Randome Sampling Mode (SM).
+	 * value of 0b11 is reserved.
+	 */
+	if (sample_mode == 0x3)
+		return -1;
+
+	/*
+	 * Check for all reserved value
+	 */
+	switch (val) {
+	case 0x5:
+	case 0x9:
+	case 0xD:
+	case 0x19:
+	case 0x1D:
+	case 0x1A:
+	case 0x1E:
+		return -1;
+	}
+
+	/*
+	 * MMCRA[48:51]/[52:55]) Threshold Start/Stop
+	 * Events Selection.
+	 * 0b11110000/0b00001111 is reserved.
+	 */
+	val = (event >> EVENT_THR_CTL_SHIFT) & EVENT_THR_CTL_MASK;
+	if (((val & 0xF0) == 0xF0) || ((val & 0xF) == 0xF))
+		return -1;
+
+	return 0;
+}

diff --git a/arch/powerpc/perf/isa207-common.h b/arch/powerpc/perf/isa207-common.h
index 1af0e8c97ac7..ae8eaf05efd1 100644
--- a/arch/powerpc/perf/isa207-common.h
+++ b/arch/powerpc/perf/isa207-common.h

@@ -280,4 +280,6 @@ void isa207_get_mem_data_src(union perf_mem_data_src *dsrc, u32 flags,
 							struct pt_regs *regs);
 void isa207_get_mem_weight(u64 *weight);
 
+int isa3_X_check_attr_config(struct perf_event *ev);
+
 #endif

diff --git a/arch/powerpc/perf/power10-pmu.c b/arch/powerpc/perf/power10-pmu.c
index a901c1348cad..bc64354cab6a 100644
--- a/arch/powerpc/perf/power10-pmu.c
+++ b/arch/powerpc/perf/power10-pmu.c

@@ -106,6 +106,18 @@ static int power10_get_alternatives(u64 event, unsigned int flags, u64 alt[])
 	return num_alt;
 }
 
+static int power10_check_attr_config(struct perf_event *ev)
+{
+	u64 val;
+	u64 event = ev->attr.config;
+
+	val = (event >> EVENT_SAMPLE_SHIFT) & EVENT_SAMPLE_MASK;
+	if (val == 0x10 || isa3_X_check_attr_config(ev))
+		return -1;
+
+	return 0;
+}
+
 GENERIC_EVENT_ATTR(cpu-cycles,			PM_RUN_CYC);
 GENERIC_EVENT_ATTR(instructions,		PM_RUN_INST_CMPL);
 GENERIC_EVENT_ATTR(branch-instructions,		PM_BR_CMPL);

@@ -559,6 +571,7 @@ static struct power_pmu power10_pmu = {
 	.attr_groups		= power10_pmu_attr_groups,
 	.bhrb_nr		= 32,
 	.capabilities           = PERF_PMU_CAP_EXTENDED_REGS,
+	.check_attr_config	= power10_check_attr_config,
 };
 
 int init_power10_pmu(void)

diff --git a/arch/powerpc/perf/power9-pmu.c b/arch/powerpc/perf/power9-pmu.c
index 2a57e93a79dc..b3b9b226d053 100644
--- a/arch/powerpc/perf/power9-pmu.c
+++ b/arch/powerpc/perf/power9-pmu.c

@@ -151,6 +151,18 @@ static int power9_get_alternatives(u64 event, unsigned int flags, u64 alt[])
 	return num_alt;
 }
 
+static int power9_check_attr_config(struct perf_event *ev)
+{
+	u64 val;
+	u64 event = ev->attr.config;
+
+	val = (event >> EVENT_SAMPLE_SHIFT) & EVENT_SAMPLE_MASK;
+	if (val == 0xC || isa3_X_check_attr_config(ev))
+		return -1;
+
+	return 0;
+}
+
 GENERIC_EVENT_ATTR(cpu-cycles,			PM_CYC);
 GENERIC_EVENT_ATTR(stalled-cycles-frontend,	PM_ICT_NOSLOT_CYC);
 GENERIC_EVENT_ATTR(stalled-cycles-backend,	PM_CMPLU_STALL);

@@ -437,6 +449,7 @@ static struct power_pmu power9_pmu = {
 	.attr_groups		= power9_pmu_attr_groups,
 	.bhrb_nr		= 32,
 	.capabilities           = PERF_PMU_CAP_EXTENDED_REGS,
+	.check_attr_config	= power9_check_attr_config,
 };
 
 int init_power9_pmu(void)

-- 
2.26.2

On Wed, Feb 24, 2021 at 07:58:39PM +0530, Madhavan Srinivasan wrote:

Introduce code to support the checking of attr.config* for
values which are reserved for a given platform.
Performance Monitoring Unit (PMU) configuration registers
have fileds that are reserved and specific values to bit fields

s/fileds/fields/

as reserved. Writing a none zero values in these fields

Should the previous sentences say something like "required values
for specific bit fields" or "specific bit fields that are reserved"?

s/none zero/non-zero/

or writing invalid value to bit fields will have unknown
behaviours.

Patch here add a generic call-back function "check_attr_config"

s/add/adds/ or "This patch adds ..." or just "Add ...".

s/spacific/specific/
s/fileds/fields/
Same comment about "specific values to bit fields be reserved", and
rewording that to be more clear.

+		 * This call-back will check the event code for same.
+		 *
+		 * Event type hardware and hw_cache will not value
+		 * invalid values in the event code which is not true
+		 * for raw event type.

I confess I don't understand what this means. (But it could be just me!)

+		 */
+		if (ppmu->check_attr_config &&
+		    ppmu->check_attr_config(event))
+			return -EINVAL;
 		break;
 	default:
 		return -ENOENT;
-- 

PC

On 2/24/21 8:17 PM, Paul A. Clarke wrote:

On Wed, Feb 24, 2021 at 07:58:39PM +0530, Madhavan Srinivasan wrote:

quoted

Introduce code to support the checking of attr.config* for
values which are reserved for a given platform.
Performance Monitoring Unit (PMU) configuration registers
have fileds that are reserved and specific values to bit fields

s/fileds/fields/

quoted

as reserved. Writing a none zero values in these fields

Should the previous sentences say something like "required values
for specific bit fields" or "specific bit fields that are reserved"?

s/none zero/non-zero/

quoted

or writing invalid value to bit fields will have unknown
behaviours.

Patch here add a generic call-back function "check_attr_config"

s/add/adds/ or "This patch adds ..." or just "Add ...".

Thanks for the review. Will fix it.

quoted

in "struct power_pmu", to be called in event_init to
check for attr.config* values for a given platform.
"check_attr_config" is valid only for raw event type.

Suggested-by: Alexey Kardashevskiy <redacted>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
---
  arch/powerpc/include/asm/perf_event_server.h |  6 ++++++
  arch/powerpc/perf/core-book3s.c              | 12 ++++++++++++
  2 files changed, 18 insertions(+)

diff --git a/arch/powerpc/include/asm/perf_event_server.h b/arch/powerpc/include/asm/perf_event_server.h
index 00e7e671bb4b..dde97d7d9253 100644
--- a/arch/powerpc/include/asm/perf_event_server.h
+++ b/arch/powerpc/include/asm/perf_event_server.h

@@ -67,6 +67,12 @@ struct power_pmu {
  	 * the pmu supports extended perf regs capability
  	 */
  	int		capabilities;
+	/*
+	 * Function to check event code for values which are
+	 * reserved. Function takes struct perf_event as input,
+	 * since event code could be spread in attr.config*
+	 */
+	int		(*check_attr_config)(struct perf_event *ev);
  };

  /*

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 6817331e22ff..679d67506299 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c

@@ -1958,6 +1958,18 @@ static int power_pmu_event_init(struct perf_event *event)

  		if (ppmu->blacklist_ev && is_event_blacklisted(ev))
  			return -EINVAL;
+		/*
+		 * PMU config registers have fileds that are
+		 * reserved and spacific values to bit fileds be reserved.

s/spacific/specific/
s/fileds/fields/
Same comment about "specific values to bit fields be reserved", and
rewording that to be more clear.

quoted

+		 * This call-back will check the event code for same.
+		 *
+		 * Event type hardware and hw_cache will not value
+		 * invalid values in the event code which is not true
+		 * for raw event type.

I confess I don't understand what this means. (But it could be just me!)

My bad. What I wanted to say was, this check is needed only

for raw event type, since tools like fuzzer use it to provide

randomized event code values for test. Will fix the comment

Thanks for the review comments.

quoted

+		 */
+		if (ppmu->check_attr_config &&
+		    ppmu->check_attr_config(event))
+			return -EINVAL;
  		break;
  	default:
  		return -ENOENT;
-- 

PC