selftests/powerpc/pmu: Add utility functions to post process the mmap buffer

Add couple of basic utility functions to post process the mmap buffer.
It includes function to read the total number of samples present in the
mmap buffer and function to get the address of the first sample.

Add function "get_intr_regs" which will return pointer to interrupt
registers present in the sample, incase sample type
PERF_SAMPLE_REGS_INTR is set.

Add functions "get_reg_value" which can be used to read any interrupt
register value from a given sample.
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220127072012.662451-5-kjain@linux.ibm.com

tools/testing/selftests/powerpc/pmu/sampling_tests/misc.c

@@ -2,6 +2,7 @@
 /*
  * Copyright 2022, Athira Rajeev, IBM Corp.
  * Copyright 2022, Madhavan Srinivasan, IBM Corp.
+ * Copyright 2022, Kajol Jain, IBM Corp.
  */
 
 #include <unistd.h>
@@ -235,3 +236,177 @@ void *__event_read_samples(void *sample_buff, size_t *size, u64 *sample_count)
 	}
 	return NULL;
 }
+
+int collect_samples(void *sample_buff)
+{
+	u64 sample_count;
+	size_t size = 0;
+
+	__event_read_samples(sample_buff, &size, &sample_count);
+	return sample_count;
+}
+
+static void *perf_read_first_sample(void *sample_buff, size_t *size)
+{
+	return __event_read_samples(sample_buff, size, NULL);
+}
+
+u64 *get_intr_regs(struct event *event, void *sample_buff)
+{
+	u64 type = event->attr.sample_type;
+	u64 *intr_regs;
+	size_t size = 0;
+
+	if ((type ^ PERF_SAMPLE_REGS_INTR))
+		return NULL;
+
+	intr_regs = (u64 *)perf_read_first_sample(sample_buff, &size);
+	if (!intr_regs)
+		return NULL;
+
+	/*
+	 * First entry in the sample buffer used to specify
+	 * PERF_SAMPLE_REGS_ABI_64, skip perf regs abi to access
+	 * interrupt registers.
+	 */
+	++intr_regs;
+
+	return intr_regs;
+}
+
+static const unsigned int __perf_reg_mask(const char *register_name)
+{
+	if (!strcmp(register_name, "R0"))
+		return 0;
+	else if (!strcmp(register_name, "R1"))
+		return 1;
+	else if (!strcmp(register_name, "R2"))
+		return 2;
+	else if (!strcmp(register_name, "R3"))
+		return 3;
+	else if (!strcmp(register_name, "R4"))
+		return 4;
+	else if (!strcmp(register_name, "R5"))
+		return 5;
+	else if (!strcmp(register_name, "R6"))
+		return 6;
+	else if (!strcmp(register_name, "R7"))
+		return 7;
+	else if (!strcmp(register_name, "R8"))
+		return 8;
+	else if (!strcmp(register_name, "R9"))
+		return 9;
+	else if (!strcmp(register_name, "R10"))
+		return 10;
+	else if (!strcmp(register_name, "R11"))
+		return 11;
+	else if (!strcmp(register_name, "R12"))
+		return 12;
+	else if (!strcmp(register_name, "R13"))
+		return 13;
+	else if (!strcmp(register_name, "R14"))
+		return 14;
+	else if (!strcmp(register_name, "R15"))
+		return 15;
+	else if (!strcmp(register_name, "R16"))
+		return 16;
+	else if (!strcmp(register_name, "R17"))
+		return 17;
+	else if (!strcmp(register_name, "R18"))
+		return 18;
+	else if (!strcmp(register_name, "R19"))
+		return 19;
+	else if (!strcmp(register_name, "R20"))
+		return 20;
+	else if (!strcmp(register_name, "R21"))
+		return 21;
+	else if (!strcmp(register_name, "R22"))
+		return 22;
+	else if (!strcmp(register_name, "R23"))
+		return 23;
+	else if (!strcmp(register_name, "R24"))
+		return 24;
+	else if (!strcmp(register_name, "R25"))
+		return 25;
+	else if (!strcmp(register_name, "R26"))
+		return 26;
+	else if (!strcmp(register_name, "R27"))
+		return 27;
+	else if (!strcmp(register_name, "R28"))
+		return 28;
+	else if (!strcmp(register_name, "R29"))
+		return 29;
+	else if (!strcmp(register_name, "R30"))
+		return 30;
+	else if (!strcmp(register_name, "R31"))
+		return 31;
+	else if (!strcmp(register_name, "NIP"))
+		return 32;
+	else if (!strcmp(register_name, "MSR"))
+		return 33;
+	else if (!strcmp(register_name, "ORIG_R3"))
+		return 34;
+	else if (!strcmp(register_name, "CTR"))
+		return 35;
+	else if (!strcmp(register_name, "LINK"))
+		return 36;
+	else if (!strcmp(register_name, "XER"))
+		return 37;
+	else if (!strcmp(register_name, "CCR"))
+		return 38;
+	else if (!strcmp(register_name, "SOFTE"))
+		return 39;
+	else if (!strcmp(register_name, "TRAP"))
+		return 40;
+	else if (!strcmp(register_name, "DAR"))
+		return 41;
+	else if (!strcmp(register_name, "DSISR"))
+		return 42;
+	else if (!strcmp(register_name, "SIER"))
+		return 43;
+	else if (!strcmp(register_name, "MMCRA"))
+		return 44;
+	else if (!strcmp(register_name, "MMCR0"))
+		return 45;
+	else if (!strcmp(register_name, "MMCR1"))
+		return 46;
+	else if (!strcmp(register_name, "MMCR2"))
+		return 47;
+	else if (!strcmp(register_name, "MMCR3"))
+		return 48;
+	else if (!strcmp(register_name, "SIER2"))
+		return 49;
+	else if (!strcmp(register_name, "SIER3"))
+		return 50;
+	else if (!strcmp(register_name, "PMC1"))
+		return 51;
+	else if (!strcmp(register_name, "PMC2"))
+		return 52;
+	else if (!strcmp(register_name, "PMC3"))
+		return 53;
+	else if (!strcmp(register_name, "PMC4"))
+		return 54;
+	else if (!strcmp(register_name, "PMC5"))
+		return 55;
+	else if (!strcmp(register_name, "PMC6"))
+		return 56;
+	else if (!strcmp(register_name, "SDAR"))
+		return 57;
+	else if (!strcmp(register_name, "SIAR"))
+		return 58;
+	else
+		return -1;
+}
+
+u64 get_reg_value(u64 *intr_regs, char *register_name)
+{
+	int register_bit_position;
+
+	register_bit_position = __perf_reg_mask(register_name);
+
+	if (register_bit_position < 0 || (!((platform_extended_mask >>
+			(register_bit_position - 1)) & 1)))
+		return -1;
+
+	return *(intr_regs + register_bit_position);
+}

tools/testing/selftests/powerpc/pmu/sampling_tests/misc.h

@@ -2,6 +2,7 @@
 /*
  * Copyright 2022, Athira Rajeev, IBM Corp.
  * Copyright 2022, Madhavan Srinivasan, IBM Corp.
+ * Copyright 2022, Kajol Jain, IBM Corp.
  */
 
 #include "../event.h"
@@ -43,3 +44,6 @@ extern int check_pvr_for_sampling_tests(void);
 
 void *event_sample_buf_mmap(int fd, int mmap_pages);
 void *__event_read_samples(void *sample_buff, size_t *size, u64 *sample_count);
+int collect_samples(void *sample_buff);
+u64 *get_intr_regs(struct event *event, void *sample_buff);
+u64 get_reg_value(u64 *intr_regs, char *register_name);