s390/cpumf: remove raw event support in basic-only sampling mode

Pu Hou · Martin Schwidefsky · commit 3d43b981eb84 · 2017-11-16T15:06:09.000+01:00
Raw sample was implemented to export the diagnostic samples.
With having this achieved with AUX buffers, there is no requirement
for basic samples to export raw data.  In particular, most basic
sampling information are consumed for creating the perf event sample.

Signed-off-by: Pu Hou &lt;bjhoupu@linux.vnet.ibm.com&gt;
Reviewed-by: Hendrik Brueckner &lt;brueckner@linux.vnet.ibm.com&gt;
Signed-off-by: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
diff --git a/arch/s390/include/asm/perf_event.h b/arch/s390/include/asm/perf_event.h
@@ -64,27 +64,10 @@ struct perf_sf_sde_regs {
 #define REG_OVERFLOW		1
 #define OVERFLOW_REG(hwc)	((hwc)->extra_reg.config)
 #define SFB_ALLOC_REG(hwc)	((hwc)->extra_reg.alloc)
-#define RAWSAMPLE_REG(hwc)	((hwc)->config)
 #define TEAR_REG(hwc)		((hwc)->last_tag)
 #define SAMPL_RATE(hwc)		((hwc)->event_base)
 #define SAMPL_FLAGS(hwc)	((hwc)->config_base)
 #define SAMPL_DIAG_MODE(hwc)	(SAMPL_FLAGS(hwc) & PERF_CPUM_SF_DIAG_MODE)
 #define SDB_FULL_BLOCKS(hwc)	(SAMPL_FLAGS(hwc) & PERF_CPUM_SF_FULL_BLOCKS)
 
-/* Structure for sampling data entries to be passed as perf raw sample data
- * to user space.  Note that raw sample data must be aligned and, thus, might
- * be padded with zeros.
- */
-struct sf_raw_sample {
-#define SF_RAW_SAMPLE_BASIC	PERF_CPUM_SF_BASIC_MODE
-#define SF_RAW_SAMPLE_DIAG	PERF_CPUM_SF_DIAG_MODE
-	u64			format;
-	u32			 size;	  /* Size of sf_raw_sample */
-	u16			bsdes;	  /* Basic-sampling data entry size */
-	u16			dsdes;	  /* Diagnostic-sampling data entry size */
-	struct hws_basic_entry	basic;	  /* Basic-sampling data entry */
-	struct hws_diag_entry	 diag;	  /* Diagnostic-sampling data entry */
-	u8		    padding[];	  /* Padding to next multiple of 8 */
-} __packed;
-
 #endif /* _ASM_S390_PERF_EVENT_H */
diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
@@ -351,22 +351,6 @@ static void sfb_init_allocs(unsigned long num, struct hw_perf_event *hwc)
 	sfb_account_allocs(num, hwc);
 }
 
-static size_t event_sample_size(struct hw_perf_event *hwc)
-{
-	struct sf_raw_sample *sfr = (struct sf_raw_sample *) RAWSAMPLE_REG(hwc);
-	size_t sample_size;
-
-	/* The sample size depends on the sampling function: The basic-sampling
-	 * function must be always enabled, diagnostic-sampling function is
-	 * optional.
-	 */
-	sample_size = sfr->bsdes;
-	if (SAMPL_DIAG_MODE(hwc))
-		sample_size += sfr->dsdes;
-
-	return sample_size;
-}
-
 static void deallocate_buffers(struct cpu_hw_sf *cpuhw)
 {
 	if (cpuhw->sfb.sdbt)
@@ -376,35 +360,7 @@ static void deallocate_buffers(struct cpu_hw_sf *cpuhw)
 static int allocate_buffers(struct cpu_hw_sf *cpuhw, struct hw_perf_event *hwc)
 {
 	unsigned long n_sdb, freq, factor;
-	size_t sfr_size, sample_size;
-	struct sf_raw_sample *sfr;
-
-	/* Allocate raw sample buffer
-	 *
-	 *    The raw sample buffer is used to temporarily store sampling data
-	 *    entries for perf raw sample processing.  The buffer size mainly
-	 *    depends on the size of diagnostic-sampling data entries which is
-	 *    machine-specific.  The exact size calculation includes:
-	 *	1. The first 4 bytes of diagnostic-sampling data entries are
-	 *	   already reflected in the sf_raw_sample structure.  Subtract
-	 *	   these bytes.
-	 *	2. The perf raw sample data must be 8-byte aligned (u64) and
-	 *	   perf's internal data size must be considered too.  So add
-	 *	   an additional u32 for correct alignment and subtract before
-	 *	   allocating the buffer.
-	 *	3. Store the raw sample buffer pointer in the perf event
-	 *	   hardware structure.
-	 */
-	sfr_size = ALIGN((sizeof(*sfr) - sizeof(sfr->diag) + cpuhw->qsi.dsdes) +
-			 sizeof(u32), sizeof(u64));
-	sfr_size -= sizeof(u32);
-	sfr = kzalloc(sfr_size, GFP_KERNEL);
-	if (!sfr)
-		return -ENOMEM;
-	sfr->size = sfr_size;
-	sfr->bsdes = cpuhw->qsi.bsdes;
-	sfr->dsdes = cpuhw->qsi.dsdes;
-	RAWSAMPLE_REG(hwc) = (unsigned long) sfr;
+	size_t sample_size;
 
 	/* Calculate sampling buffers using 4K pages
 	 *
@@ -430,7 +386,7 @@ static int allocate_buffers(struct cpu_hw_sf *cpuhw, struct hw_perf_event *hwc)
 	 *	 ensure a minimum of CPUM_SF_MIN_SDBT (one table can manage up
 	 *	 to 511 SDBs).
 	 */
-	sample_size = event_sample_size(hwc);
+	sample_size = sizeof(struct hws_basic_entry);
 	freq = sample_rate_to_freq(&cpuhw->qsi, SAMPL_RATE(hwc));
 	factor = 1;
 	n_sdb = DIV_ROUND_UP(freq, factor * ((PAGE_SIZE-64) / sample_size));
@@ -629,10 +585,6 @@ static int reserve_pmc_hardware(void)
 
 static void hw_perf_event_destroy(struct perf_event *event)
 {
-	/* Free raw sample buffer */
-	if (RAWSAMPLE_REG(&event->hw))
-		kfree((void *) RAWSAMPLE_REG(&event->hw));
-
 	/* Release PMC if this is the last perf event */
 	if (!atomic_add_unless(&num_events, -1, 1)) {
 		mutex_lock(&pmc_reserve_mutex);
@@ -652,15 +604,8 @@ static void hw_init_period(struct hw_perf_event *hwc, u64 period)
 static void hw_reset_registers(struct hw_perf_event *hwc,
 			       unsigned long *sdbt_origin)
 {
-	struct sf_raw_sample *sfr;
-
 	/* (Re)set to first sample-data-block-table */
 	TEAR_REG(hwc) = (unsigned long) sdbt_origin;
-
-	/* (Re)set raw sampling buffer register */
-	sfr = (struct sf_raw_sample *) RAWSAMPLE_REG(hwc);
-	memset(&sfr->basic, 0, sizeof(sfr->basic));
-	memset(&sfr->diag, 0, sfr->dsdes);
 }
 
 static unsigned long hw_limit_rate(const struct hws_qsi_info_block *si,
@@ -986,22 +931,16 @@ static int perf_exclude_event(struct perf_event *event, struct pt_regs *regs,
  *
  * Return non-zero if an event overflow occurred.
  */
-static int perf_push_sample(struct perf_event *event, struct sf_raw_sample *sfr)
+static int perf_push_sample(struct perf_event *event,
+			    struct hws_basic_entry *basic)
 {
 	int overflow;
 	struct pt_regs regs;
 	struct perf_sf_sde_regs *sde_regs;
 	struct perf_sample_data data;
-	struct perf_raw_record raw = {
-		.frag = {
-			.size = sfr->size,
-			.data = sfr,
-		},
-	};
 
 	/* Setup perf sample */
 	perf_sample_data_init(&data, 0, event->hw.last_period);
-	data.raw = &raw;
 
 	/* Setup pt_regs to look like an CPU-measurement external interrupt
 	 * using the Program Request Alert code.  The regs.int_parm_long
@@ -1013,11 +952,11 @@ static int perf_push_sample(struct perf_event *event, struct sf_raw_sample *sfr)
 	regs.int_parm = CPU_MF_INT_SF_PRA;
 	sde_regs = (struct perf_sf_sde_regs *) &regs.int_parm_long;
 
-	psw_bits(regs.psw).ia	= sfr->basic.ia;
-	psw_bits(regs.psw).dat	= sfr->basic.T;
-	psw_bits(regs.psw).wait = sfr->basic.W;
-	psw_bits(regs.psw).pstate = sfr->basic.P;
-	psw_bits(regs.psw).as	= sfr->basic.AS;
+	psw_bits(regs.psw).ia	= basic->ia;
+	psw_bits(regs.psw).dat	= basic->T;
+	psw_bits(regs.psw).wait = basic->W;
+	psw_bits(regs.psw).pstate = basic->P;
+	psw_bits(regs.psw).as	= basic->AS;
 
 	/*
 	 * Use the hardware provided configuration level to decide if the
@@ -1030,15 +969,15 @@ static int perf_push_sample(struct perf_event *event, struct sf_raw_sample *sfr)
 	 * If the value differs from 0xffff (the host value), we assume to
 	 * be a KVM guest.
 	 */
-	switch (sfr->basic.CL) {
+	switch (basic->CL) {
 	case 1: /* logical partition */
 		sde_regs->in_guest = 0;
 		break;
 	case 2: /* virtual machine */
 		sde_regs->in_guest = 1;
 		break;
 	default: /* old machine, use heuristics */
-		if (sfr->basic.gpp || sfr->basic.prim_asn != 0xffff)
+		if (basic->gpp || basic->prim_asn != 0xffff)
 			sde_regs->in_guest = 1;
 		break;
 	}
@@ -1060,75 +999,12 @@ static void perf_event_count_update(struct perf_event *event, u64 count)
 	local64_add(count, &event->count);
 }
 
-static int sample_format_is_valid(struct hws_combined_entry *sample,
-				   unsigned int flags)
-{
-	if (likely(flags & PERF_CPUM_SF_BASIC_MODE))
-		/* Only basic-sampling data entries with data-entry-format
-		 * version of 0x0001 can be processed.
-		 */
-		if (sample->basic.def != 0x0001)
-			return 0;
-	if (flags & PERF_CPUM_SF_DIAG_MODE)
-		/* The data-entry-format number of diagnostic-sampling data
-		 * entries can vary.  Because diagnostic data is just passed
-		 * through, do only a sanity check on the DEF.
-		 */
-		if (sample->diag.def < 0x8001)
-			return 0;
-	return 1;
-}
-
-static int sample_is_consistent(struct hws_combined_entry *sample,
-				unsigned long flags)
-{
-	/* This check applies only to basic-sampling data entries of potentially
-	 * combined-sampling data entries.  Invalid entries cannot be processed
-	 * by the PMU and, thus, do not deliver an associated
-	 * diagnostic-sampling data entry.
-	 */
-	if (unlikely(!(flags & PERF_CPUM_SF_BASIC_MODE)))
-		return 0;
-	/*
-	 * Samples are skipped, if they are invalid or for which the
-	 * instruction address is not predictable, i.e., the wait-state bit is
-	 * set.
-	 */
-	if (sample->basic.I || sample->basic.W)
-		return 0;
-	return 1;
-}
-
-static void reset_sample_slot(struct hws_combined_entry *sample,
-			      unsigned long flags)
-{
-	if (likely(flags & PERF_CPUM_SF_BASIC_MODE))
-		sample->basic.def = 0;
-	if (flags & PERF_CPUM_SF_DIAG_MODE)
-		sample->diag.def = 0;
-}
-
-static void sfr_store_sample(struct sf_raw_sample *sfr,
-			     struct hws_combined_entry *sample)
-{
-	if (likely(sfr->format & PERF_CPUM_SF_BASIC_MODE))
-		sfr->basic = sample->basic;
-	if (sfr->format & PERF_CPUM_SF_DIAG_MODE)
-		memcpy(&sfr->diag, &sample->diag, sfr->dsdes);
-}
-
-static void debug_sample_entry(struct hws_combined_entry *sample,
-			       struct hws_trailer_entry *te,
-			       unsigned long flags)
+static void debug_sample_entry(struct hws_basic_entry *sample,
+			       struct hws_trailer_entry *te)
 {
 	debug_sprintf_event(sfdbg, 4, "hw_collect_samples: Found unknown "
-			    "sampling data entry: te->f=%i basic.def=%04x (%p)"
-			    " diag.def=%04x (%p)\n", te->f,
-			    sample->basic.def, &sample->basic,
-			    (flags & PERF_CPUM_SF_DIAG_MODE)
-					? sample->diag.def : 0xFFFF,
-			    (flags & PERF_CPUM_SF_DIAG_MODE)
-					?  &sample->diag : NULL);
+			    "sampling data entry: te->f=%i basic.def=%04x (%p)\n",
+			    te->f, sample->def, sample);
 }
 
 /* hw_collect_samples() - Walk through a sample-data-block and collect samples
@@ -1154,44 +1030,37 @@ static void debug_sample_entry(struct hws_combined_entry *sample,
 static void hw_collect_samples(struct perf_event *event, unsigned long *sdbt,
 			       unsigned long long *overflow)
 {
-	unsigned long flags = SAMPL_FLAGS(&event->hw);
-	struct hws_combined_entry *sample;
 	struct hws_trailer_entry *te;
-	struct sf_raw_sample *sfr;
-	size_t sample_size;
-
-	/* Prepare and initialize raw sample data */
-	sfr = (struct sf_raw_sample *) RAWSAMPLE_REG(&event->hw);
-	sfr->format = flags & PERF_CPUM_SF_MODE_MASK;
+	struct hws_basic_entry *sample;
 
-	sample_size = event_sample_size(&event->hw);
 	te = (struct hws_trailer_entry *) trailer_entry_ptr(*sdbt);
-	sample = (struct hws_combined_entry *) *sdbt;
+	sample = (struct hws_basic_entry *) *sdbt;
 	while ((unsigned long *) sample < (unsigned long *) te) {
 		/* Check for an empty sample */
-		if (!sample->basic.def)
+		if (!sample->def)
 			break;
 
 		/* Update perf event period */
 		perf_event_count_update(event, SAMPL_RATE(&event->hw));
 
-		/* Check sampling data entry */
-		if (sample_format_is_valid(sample, flags)) {
+		/* Check whether sample is valid */
+		if (sample->def == 0x0001) {
 			/* If an event overflow occurred, the PMU is stopped to
 			 * throttle event delivery.  Remaining sample data is
 			 * discarded.
 			 */
 			if (!*overflow) {
-				if (sample_is_consistent(sample, flags)) {
+				/* Check whether sample is consistent */
+				if (sample->I == 0 && sample->W == 0) {
 					/* Deliver sample data to perf */
-					sfr_store_sample(sfr, sample);
-					*overflow = perf_push_sample(event, sfr);
+					*overflow = perf_push_sample(event,
+								     sample);
 				}
 			} else
 				/* Count discarded samples */
 				*overflow += 1;
 		} else {
-			debug_sample_entry(sample, te, flags);
+			debug_sample_entry(sample, te);
 			/* Sample slot is not yet written or other record.
 			 *
 			 * This condition can occur if the buffer was reused
@@ -1207,8 +1076,8 @@ static void hw_collect_samples(struct perf_event *event, unsigned long *sdbt,
 		}
 
 		/* Reset sample slot and advance to next sample */
-		reset_sample_slot(sample, flags);
-		sample += sample_size;
+		sample->def = 0;
+		sample++;
 	}
 }
 
