hwpmc: Initial support for AMD IBS

This patch adds support for AMD IBS.  It adds a new class of performance
counter that cotains two events: ibs-fetch and ibs-op events. Unlike
most existing sampled events, IBS events provide a number of values
containing extra information regarding the sample.  To support this we
use the existing callchain event, and introduce a new flag for multipart
payloads.  The first 8 bytes of the pc_sample contains a header that
defines up to four payloads.

Sponsored by: Netflix

Reviewed by: imp,mhorne
Pull Request: https://github.com/freebsd/freebsd-src/pull/2022

14 files changed, 1130 insertions, 32 deletions

diff --git a/lib/libpmc/libpmc.c b/lib/libpmc/libpmc.c
index 10e357f55935..155da7cf6a7b 100644
--- a/lib/libpmc/libpmc.c
+++ b/lib/libpmc/libpmc.c
@@ -50,8 +50,8 @@
 #if defined(__amd64__) || defined(__i386__)
 static int k8_allocate_pmc(enum pmc_event _pe, char *_ctrspec,
     struct pmc_op_pmcallocate *_pmc_config);
-#endif
-#if defined(__amd64__) || defined(__i386__)
+static int ibs_allocate_pmc(enum pmc_event _pe, char *_ctrspec,
+    struct pmc_op_pmcallocate *_pmc_config);
 static int tsc_allocate_pmc(enum pmc_event _pe, char *_ctrspec,
     struct pmc_op_pmcallocate *_pmc_config);
 #endif
@@ -132,6 +132,7 @@ struct pmc_class_descr {
 
 PMC_CLASSDEP_TABLE(iaf, IAF);
 PMC_CLASSDEP_TABLE(k8, K8);
+PMC_CLASSDEP_TABLE(ibs, IBS);
 PMC_CLASSDEP_TABLE(armv7, ARMV7);
 PMC_CLASSDEP_TABLE(armv8, ARMV8);
 PMC_CLASSDEP_TABLE(cmn600_pmu, CMN600_PMU);
@@ -201,8 +202,7 @@ static const struct pmc_class_descr NAME##_class_table_descr =	\
 
 #if	defined(__i386__) || defined(__amd64__)
 PMC_CLASS_TABLE_DESC(k8, K8, k8, k8);
-#endif
-#if	defined(__i386__) || defined(__amd64__)
+PMC_CLASS_TABLE_DESC(ibs, IBS, ibs, ibs);
 PMC_CLASS_TABLE_DESC(tsc, TSC, tsc, tsc);
 #endif
 #if	defined(__arm__)
@@ -691,9 +691,49 @@ k8_allocate_pmc(enum pmc_event pe, char *ctrspec,
 	return (0);
 }
 
-#endif
+static int
+ibs_allocate_pmc(enum pmc_event pe, char *ctrspec,
+    struct pmc_op_pmcallocate *pmc_config)
+{
+	char *e, *p, *q;
+	uint64_t ctl;
+
+	pmc_config->pm_caps |=
+	    (PMC_CAP_SYSTEM | PMC_CAP_EDGE | PMC_CAP_PRECISE);
+	pmc_config->pm_md.pm_ibs.ibs_ctl = 0;
+
+	/* setup parsing tables */
+	switch (pe) {
+	case PMC_EV_IBS_FETCH:
+		pmc_config->pm_md.pm_ibs.ibs_type = IBS_PMC_FETCH;
+		break;
+	case PMC_EV_IBS_OP:
+		pmc_config->pm_md.pm_ibs.ibs_type = IBS_PMC_OP;
+		break;
+	default:
+		return (-1);
+	}
+
+	/* parse parameters */
+	while ((p = strsep(&ctrspec, ",")) != NULL) {
+		if (KWPREFIXMATCH(p, "ctl=")) {
+			q = strchr(p, '=');
+			if (*++q == '\0') /* skip '=' */
+				return (-1);
+
+			ctl = strtoull(q, &e, 0);
+			if (e == q || *e != '\0')
+				return (-1);
+
+			pmc_config->pm_md.pm_ibs.ibs_ctl |= ctl;
+		} else {
+			return (-1);
+		}
+	}
+
+	return (0);
+}
 
-#if	defined(__i386__) || defined(__amd64__)
 static int
 tsc_allocate_pmc(enum pmc_event pe, char *ctrspec,
     struct pmc_op_pmcallocate *pmc_config)
@@ -1268,6 +1308,10 @@ pmc_event_names_of_class(enum pmc_class cl, const char ***eventnames,
 		ev = k8_event_table;
 		count = PMC_EVENT_TABLE_SIZE(k8);
 		break;
+	case PMC_CLASS_IBS:
+		ev = ibs_event_table;
+		count = PMC_EVENT_TABLE_SIZE(ibs);
+		break;
 	case PMC_CLASS_ARMV7:
 		switch (cpu_info.pm_cputype) {
 		default:
@@ -1471,6 +1515,10 @@ pmc_init(void)
 		case PMC_CLASS_K8:
 			pmc_class_table[n++] = &k8_class_table_descr;
 			break;
+
+		case PMC_CLASS_IBS:
+			pmc_class_table[n++] = &ibs_class_table_descr;
+			break;
 #endif
 
 		case PMC_CLASS_SOFT:
@@ -1676,7 +1724,9 @@ _pmc_name_of_event(enum pmc_event pe, enum pmc_cputype cpu)
 	if (pe >= PMC_EV_K8_FIRST && pe <= PMC_EV_K8_LAST) {
 		ev = k8_event_table;
 		evfence = k8_event_table + PMC_EVENT_TABLE_SIZE(k8);
-
+	} else if (pe >= PMC_EV_IBS_FIRST && pe <= PMC_EV_IBS_LAST) {
+		ev = ibs_event_table;
+		evfence = ibs_event_table + PMC_EVENT_TABLE_SIZE(ibs);
 	} else if (pe >= PMC_EV_ARMV7_FIRST && pe <= PMC_EV_ARMV7_LAST) {
 		switch (cpu) {
 		case PMC_CPU_ARMV7_CORTEX_A8:
diff --git a/sys/amd64/include/pmc_mdep.h b/sys/amd64/include/pmc_mdep.h
index 5c20d8473855..24b785312a16 100644
--- a/sys/amd64/include/pmc_mdep.h
+++ b/sys/amd64/include/pmc_mdep.h
@@ -41,6 +41,7 @@ struct pmc_mdep;
 
 #include <dev/hwpmc/hwpmc_amd.h>
 #include <dev/hwpmc/hwpmc_core.h>
+#include <dev/hwpmc/hwpmc_ibs.h>
 #include <dev/hwpmc/hwpmc_tsc.h>
 #include <dev/hwpmc/hwpmc_uncore.h>
 
@@ -51,6 +52,7 @@ struct pmc_mdep;
  */
 #define	PMC_MDEP_CLASS_INDEX_TSC	1
 #define	PMC_MDEP_CLASS_INDEX_K8		2
+#define	PMC_MDEP_CLASS_INDEX_IBS	3
 #define	PMC_MDEP_CLASS_INDEX_P4		2
 #define	PMC_MDEP_CLASS_INDEX_IAP	2
 #define	PMC_MDEP_CLASS_INDEX_IAF	3
@@ -62,6 +64,7 @@ struct pmc_mdep;
  *
  * TSC		The timestamp counter
  * K8		AMD Athlon64 and Opteron PMCs in 64 bit mode.
+ * IBS		AMD IBS
  * PIV		Intel P4/HTT and P4/EMT64
  * IAP		Intel Core/Core2/Atom CPUs in 64 bits mode.
  * IAF		Intel fixed-function PMCs in Core2 and later CPUs.
@@ -71,6 +74,7 @@ struct pmc_mdep;
 
 union pmc_md_op_pmcallocate  {
 	struct pmc_md_amd_op_pmcallocate	pm_amd;
+	struct pmc_md_ibs_op_pmcallocate	pm_ibs;
 	struct pmc_md_iap_op_pmcallocate	pm_iap;
 	struct pmc_md_ucf_op_pmcallocate	pm_ucf;
 	struct pmc_md_ucp_op_pmcallocate	pm_ucp;
@@ -85,6 +89,7 @@ union pmc_md_op_pmcallocate  {
 
 union pmc_md_pmc {
 	struct pmc_md_amd_pmc	pm_amd;
+	struct pmc_md_ibs_pmc	pm_ibs;
 	struct pmc_md_iaf_pmc	pm_iaf;
 	struct pmc_md_iap_pmc	pm_iap;
 	struct pmc_md_ucf_pmc	pm_ucf;
diff --git a/sys/conf/files.x86 b/sys/conf/files.x86
index fabcd5d9ebe5..8a7e0b78feb4 100644
--- a/sys/conf/files.x86
+++ b/sys/conf/files.x86
@@ -114,6 +114,7 @@ dev/hptrr/hptrr_osm_bsd.c	optional	hptrr
 dev/hptrr/hptrr_config.c	optional	hptrr
 dev/hptrr/$M-elf.hptrr_lib.o	optional	hptrr
 dev/hwpmc/hwpmc_amd.c		optional	hwpmc
+dev/hwpmc/hwpmc_ibs.c		optional	hwpmc
 dev/hwpmc/hwpmc_intel.c		optional	hwpmc
 dev/hwpmc/hwpmc_core.c		optional	hwpmc
 dev/hwpmc/hwpmc_uncore.c	optional	hwpmc
diff --git a/sys/dev/hwpmc/hwpmc_amd.c b/sys/dev/hwpmc/hwpmc_amd.c
index b34cbffcffa8..cf44f9362a72 100644
--- a/sys/dev/hwpmc/hwpmc_amd.c
+++ b/sys/dev/hwpmc/hwpmc_amd.c
@@ -543,6 +543,10 @@ amd_intr(struct trapframe *tf)
 
 	pac = amd_pcpu[cpu];
 
+	retval = pmc_ibs_intr(tf);
+	if (retval)
+		goto done;
+
 	/*
 	 * look for all PMCs that have interrupted:
 	 * - look for a running, sampling PMC which has overflowed
@@ -613,6 +617,7 @@ amd_intr(struct trapframe *tf)
 		}
 	}
 
+done:
 	if (retval)
 		counter_u64_add(pmc_stats.pm_intr_processed, 1);
 	else
@@ -760,7 +765,7 @@ pmc_amd_initialize(void)
 	struct pmc_classdep *pcd;
 	struct pmc_mdep *pmc_mdep;
 	enum pmc_cputype cputype;
-	int error, i, ncpus;
+	int error, i, ncpus, nclasses;
 	int family, model, stepping;
 	int amd_core_npmcs, amd_l3_npmcs, amd_df_npmcs;
 	struct amd_descr *d;
@@ -884,10 +889,16 @@ pmc_amd_initialize(void)
 	    M_WAITOK | M_ZERO);
 
 	/*
-	 * These processors have two classes of PMCs: the TSC and
-	 * programmable PMCs.
+	 * These processors have two or three classes of PMCs: the TSC,
+	 * programmable PMCs, and AMD IBS.
 	 */
-	pmc_mdep = pmc_mdep_alloc(2);
+	if ((amd_feature2 & AMDID2_IBS) != 0) {
+		nclasses = 3;
+	} else {
+		nclasses = 2;
+	}
+
+	pmc_mdep = pmc_mdep_alloc(nclasses);
 
 	ncpus = pmc_cpu_max();
 
@@ -927,6 +938,12 @@ pmc_amd_initialize(void)
 
 	PMCDBG0(MDP, INI, 0, "amd-initialize");
 
+	if (nclasses >= 3) {
+		error = pmc_ibs_initialize(pmc_mdep, ncpus);
+		if (error != 0)
+			goto error;
+	}
+
 	return (pmc_mdep);
 
 error:
diff --git a/sys/dev/hwpmc/hwpmc_ibs.c b/sys/dev/hwpmc/hwpmc_ibs.c
new file mode 100644
index 000000000000..66d3260cf040
--- /dev/null
+++ b/sys/dev/hwpmc/hwpmc_ibs.c
@@ -0,0 +1,614 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2026, Ali Jose Mashtizadeh
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/* Support for the AMD IBS */
+
+#include <sys/param.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
+#include <sys/pcpu.h>
+#include <sys/pmc.h>
+#include <sys/pmckern.h>
+#include <sys/pmclog.h>
+#include <sys/smp.h>
+#include <sys/systm.h>
+
+#include <machine/cpu.h>
+#include <machine/cpufunc.h>
+#include <machine/md_var.h>
+#include <machine/specialreg.h>
+
+#define	IBS_STOP_ITER		50 /* Stopping iterations */
+
+/* AMD IBS PMCs */
+struct ibs_descr {
+	struct pmc_descr pm_descr;  /* "base class" */
+};
+
+/*
+ * Globals
+ */
+static uint64_t ibs_features;
+
+/*
+ * Per-processor information
+ */
+#define	IBS_CPU_RUNNING		1
+#define	IBS_CPU_STOPPING	2
+#define	IBS_CPU_STOPPED		3
+
+struct ibs_cpu {
+	int		pc_status;
+	struct pmc_hw	pc_ibspmcs[IBS_NPMCS];
+};
+static struct ibs_cpu **ibs_pcpu;
+
+/*
+ * Read a PMC value from the MSR.
+ */
+static int
+ibs_read_pmc(int cpu, int ri, struct pmc *pm, pmc_value_t *v)
+{
+
+	KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
+	    ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
+	KASSERT(ri >= 0 && ri < IBS_NPMCS,
+	    ("[ibs,%d] illegal row-index %d", __LINE__, ri));
+	KASSERT(ibs_pcpu[cpu],
+	    ("[ibs,%d] null per-cpu, cpu %d", __LINE__, cpu));
+
+	/* read the IBS ctl */
+	switch (ri) {
+	case IBS_PMC_FETCH:
+		*v = rdmsr(IBS_FETCH_CTL);
+		break;
+	case IBS_PMC_OP:
+		*v = rdmsr(IBS_OP_CTL);
+		break;
+	}
+
+	PMCDBG2(MDP, REA, 2, "ibs-read id=%d -> %jd", ri, *v);
+
+	return (0);
+}
+
+/*
+ * Write a PMC MSR.
+ */
+static int
+ibs_write_pmc(int cpu, int ri, struct pmc *pm, pmc_value_t v)
+{
+
+	KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
+	    ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
+	KASSERT(ri >= 0 && ri < IBS_NPMCS,
+	    ("[ibs,%d] illegal row-index %d", __LINE__, ri));
+
+	PMCDBG3(MDP, WRI, 1, "ibs-write cpu=%d ri=%d v=%jx", cpu, ri, v);
+
+	return (0);
+}
+
+/*
+ * Configure hardware PMC according to the configuration recorded in 'pm'.
+ */
+static int
+ibs_config_pmc(int cpu, int ri, struct pmc *pm)
+{
+	struct pmc_hw *phw;
+
+	PMCDBG3(MDP, CFG, 1, "cpu=%d ri=%d pm=%p", cpu, ri, pm);
+
+	KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
+	    ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
+	KASSERT(ri >= 0 && ri < IBS_NPMCS,
+	    ("[ibs,%d] illegal row-index %d", __LINE__, ri));
+
+	phw = &ibs_pcpu[cpu]->pc_ibspmcs[ri];
+
+	KASSERT(pm == NULL || phw->phw_pmc == NULL,
+	    ("[ibs,%d] pm=%p phw->pm=%p hwpmc not unconfigured",
+		__LINE__, pm, phw->phw_pmc));
+
+	phw->phw_pmc = pm;
+
+	return (0);
+}
+
+/*
+ * Retrieve a configured PMC pointer from hardware state.
+ */
+static int
+ibs_get_config(int cpu, int ri, struct pmc **ppm)
+{
+
+	*ppm = ibs_pcpu[cpu]->pc_ibspmcs[ri].phw_pmc;
+
+	return (0);
+}
+
+/*
+ * Check if a given PMC allocation is feasible.
+ */
+static int
+ibs_allocate_pmc(int cpu __unused, int ri, struct pmc *pm,
+    const struct pmc_op_pmcallocate *a)
+{
+	uint64_t caps, config;
+
+	KASSERT(ri >= 0 && ri < IBS_NPMCS,
+	    ("[ibs,%d] illegal row index %d", __LINE__, ri));
+
+	/* check class match */
+	if (a->pm_class != PMC_CLASS_IBS)
+		return (EINVAL);
+	if (a->pm_md.pm_ibs.ibs_type != ri)
+		return (EINVAL);
+
+	caps = pm->pm_caps;
+
+	PMCDBG2(MDP, ALL, 1, "ibs-allocate ri=%d caps=0x%x", ri, caps);
+
+	if ((caps & PMC_CAP_SYSTEM) == 0)
+		return (EINVAL);
+
+	config = a->pm_md.pm_ibs.ibs_ctl;
+	pm->pm_md.pm_ibs.ibs_ctl = config;
+
+	PMCDBG2(MDP, ALL, 2, "ibs-allocate ri=%d -> config=0x%x", ri, config);
+
+	return (0);
+}
+
+/*
+ * Release machine dependent state associated with a PMC.  This is a
+ * no-op on this architecture.
+ */
+static int
+ibs_release_pmc(int cpu, int ri, struct pmc *pmc __unused)
+{
+	struct pmc_hw *phw __diagused;
+
+	KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
+	    ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
+	KASSERT(ri >= 0 && ri < IBS_NPMCS,
+	    ("[ibs,%d] illegal row-index %d", __LINE__, ri));
+
+	PMCDBG1(MDP, ALL, 1, "ibs-release ri=%d", ri);
+
+	phw = &ibs_pcpu[cpu]->pc_ibspmcs[ri];
+
+	KASSERT(phw->phw_pmc == NULL,
+	    ("[ibs,%d] PHW pmc %p non-NULL", __LINE__, phw->phw_pmc));
+
+	return (0);
+}
+
+/*
+ * Start a PMC.
+ */
+static int
+ibs_start_pmc(int cpu __diagused, int ri, struct pmc *pm)
+{
+	uint64_t config;
+
+	KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
+	    ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
+	KASSERT(ri >= 0 && ri < IBS_NPMCS,
+	    ("[ibs,%d] illegal row-index %d", __LINE__, ri));
+
+	PMCDBG2(MDP, STA, 1, "ibs-start cpu=%d ri=%d", cpu, ri);
+
+	/*
+	 * This is used to handle spurious NMIs.  All that matters is that it
+	 * is not in the stopping state.
+	 */
+	atomic_store_int(&ibs_pcpu[cpu]->pc_status, IBS_CPU_RUNNING);
+
+	/*
+	 * Turn on the ENABLE bit.  Zeroing out the control register eliminates
+	 * stale valid bits from spurious NMIs and it resets the counter.
+	 */
+	switch (ri) {
+	case IBS_PMC_FETCH:
+		wrmsr(IBS_FETCH_CTL, 0);
+		config = pm->pm_md.pm_ibs.ibs_ctl | IBS_FETCH_CTL_ENABLE;
+		wrmsr(IBS_FETCH_CTL, config);
+		break;
+	case IBS_PMC_OP:
+		wrmsr(IBS_OP_CTL, 0);
+		config = pm->pm_md.pm_ibs.ibs_ctl | IBS_OP_CTL_ENABLE;
+		wrmsr(IBS_OP_CTL, config);
+		break;
+	}
+
+	return (0);
+}
+
+/*
+ * Stop a PMC.
+ */
+static int
+ibs_stop_pmc(int cpu __diagused, int ri, struct pmc *pm)
+{
+	int i;
+	uint64_t config;
+
+	KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
+	    ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
+	KASSERT(ri >= 0 && ri < IBS_NPMCS,
+	    ("[ibs,%d] illegal row-index %d", __LINE__, ri));
+
+	PMCDBG1(MDP, STO, 1, "ibs-stop ri=%d", ri);
+
+	/*
+	 * Turn off the ENABLE bit, but unfortunately there are a few quirks
+	 * that generate excess NMIs.  Workaround #420 in the Revision Guide
+	 * for AMD Family 10h Processors 41322 Rev. 3.92 March 2012. requires
+	 * that we clear the count before clearing enable.
+	 *
+	 * Even after clearing the counter spurious NMIs are still possible so
+	 * we use a per-CPU atomic variable to notify the interrupt handler we
+	 * are stopping and discard spurious NMIs.  We then retry clearing the
+	 * control register for 50us.  This gives us enough time and ensures
+	 * that the valid bit is not accidently stuck after a spurious NMI.
+	 */
+	config = pm->pm_md.pm_ibs.ibs_ctl;
+
+	atomic_store_int(&ibs_pcpu[cpu]->pc_status, IBS_CPU_STOPPING);
+
+	switch (ri) {
+	case IBS_PMC_FETCH:
+		wrmsr(IBS_FETCH_CTL, config & ~IBS_FETCH_CTL_MAXCNTMASK);
+		DELAY(1);
+		config &= ~IBS_FETCH_CTL_ENABLE;
+		wrmsr(IBS_FETCH_CTL, config);
+		break;
+	case IBS_PMC_OP:
+		wrmsr(IBS_FETCH_CTL, config & ~IBS_FETCH_CTL_MAXCNTMASK);
+		DELAY(1);
+		config &= ~IBS_OP_CTL_ENABLE;
+		wrmsr(IBS_OP_CTL, config);
+		break;
+	}
+
+	for (i = 0; i < IBS_STOP_ITER; i++) {
+		DELAY(1);
+
+		switch (ri) {
+		case IBS_PMC_FETCH:
+			wrmsr(IBS_FETCH_CTL, 0);
+			break;
+		case IBS_PMC_OP:
+			wrmsr(IBS_OP_CTL, 0);
+			break;
+		}
+	}
+
+	atomic_store_int(&ibs_pcpu[cpu]->pc_status, IBS_CPU_STOPPED);
+
+	return (0);
+}
+
+static void
+pmc_ibs_process_fetch(struct pmc *pm, struct trapframe *tf, uint64_t config)
+{
+	struct pmc_multipart mpd;
+
+	if (pm == NULL)
+		return;
+
+	if (pm->pm_state != PMC_STATE_RUNNING)
+		return;
+
+	memset(&mpd, 0, sizeof(mpd));
+
+	mpd.pl_type = PMC_CC_MULTIPART_IBS_FETCH;
+	mpd.pl_length = 4;
+	mpd.pl_mpdata[PMC_MPIDX_FETCH_CTL] = config;
+	if (ibs_features) {
+		mpd.pl_mpdata[PMC_MPIDX_FETCH_EXTCTL] = rdmsr(IBS_FETCH_EXTCTL);
+	}
+	mpd.pl_mpdata[PMC_MPIDX_FETCH_CTL] = config;
+	mpd.pl_mpdata[PMC_MPIDX_FETCH_LINADDR] = rdmsr(IBS_FETCH_LINADDR);
+	if ((config & IBS_FETCH_CTL_PHYSADDRVALID) != 0) {
+		mpd.pl_mpdata[PMC_MPIDX_FETCH_PHYSADDR] =
+		    rdmsr(IBS_FETCH_PHYSADDR);
+	}
+
+	pmc_process_interrupt_mp(PMC_HR, pm, tf, &mpd);
+}
+
+static void
+pmc_ibs_process_op(struct pmc *pm, struct trapframe *tf, uint64_t config)
+{
+	struct pmc_multipart mpd;
+
+	if (pm == NULL)
+		return;
+
+	if (pm->pm_state != PMC_STATE_RUNNING)
+		return;
+
+	memset(&mpd, 0, sizeof(mpd));
+
+	mpd.pl_type = PMC_CC_MULTIPART_IBS_OP;
+	mpd.pl_length = 8;
+	mpd.pl_mpdata[PMC_MPIDX_OP_CTL] = config;
+	mpd.pl_mpdata[PMC_MPIDX_OP_RIP] = rdmsr(IBS_OP_RIP);
+	mpd.pl_mpdata[PMC_MPIDX_OP_DATA] = rdmsr(IBS_OP_DATA);
+	mpd.pl_mpdata[PMC_MPIDX_OP_DATA2] = rdmsr(IBS_OP_DATA2);
+	mpd.pl_mpdata[PMC_MPIDX_OP_DATA3] = rdmsr(IBS_OP_DATA3);
+	mpd.pl_mpdata[PMC_MPIDX_OP_DC_LINADDR] = rdmsr(IBS_OP_DC_LINADDR);
+	mpd.pl_mpdata[PMC_MPIDX_OP_DC_PHYSADDR] = rdmsr(IBS_OP_DC_PHYSADDR);
+
+	pmc_process_interrupt_mp(PMC_HR, pm, tf, &mpd);
+
+	wrmsr(IBS_OP_CTL, pm->pm_md.pm_ibs.ibs_ctl | IBS_OP_CTL_ENABLE);
+}
+
+/*
+ * Interrupt handler.  This function needs to return '1' if the
+ * interrupt was this CPU's PMCs or '0' otherwise.  It is not allowed
+ * to sleep or do anything a 'fast' interrupt handler is not allowed
+ * to do.
+ */
+int
+pmc_ibs_intr(struct trapframe *tf)
+{
+	struct ibs_cpu *pac;
+	struct pmc *pm;
+	int retval, cpu;
+	uint64_t config;
+
+	cpu = curcpu;
+	KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
+	    ("[ibs,%d] out of range CPU %d", __LINE__, cpu));
+
+	PMCDBG3(MDP, INT, 1, "cpu=%d tf=%p um=%d", cpu, tf, TRAPF_USERMODE(tf));
+
+	retval = 0;
+
+	pac = ibs_pcpu[cpu];
+
+	config = rdmsr(IBS_FETCH_CTL);
+	if ((config & IBS_FETCH_CTL_VALID) != 0) {
+		pm = pac->pc_ibspmcs[IBS_PMC_FETCH].phw_pmc;
+
+		retval = 1;
+
+		pmc_ibs_process_fetch(pm, tf, config);
+	}
+
+	config = rdmsr(IBS_OP_CTL);
+	if ((retval == 0) && ((config & IBS_OP_CTL_VALID) != 0)) {
+		pm = pac->pc_ibspmcs[IBS_PMC_OP].phw_pmc;
+
+		retval = 1;
+
+		pmc_ibs_process_op(pm, tf, config);
+	}
+
+	if (retval == 0) {
+		// Lets check for a stray NMI when stopping
+		if (atomic_load_int(&pac->pc_status) == IBS_CPU_STOPPING) {
+			return (1);
+		}
+	}
+
+
+	if (retval)
+		counter_u64_add(pmc_stats.pm_intr_processed, 1);
+	else
+		counter_u64_add(pmc_stats.pm_intr_ignored, 1);
+
+	PMCDBG1(MDP, INT, 2, "retval=%d", retval);
+
+	return (retval);
+}
+
+/*
+ * Describe a PMC.
+ */
+static int
+ibs_describe(int cpu, int ri, struct pmc_info *pi, struct pmc **ppmc)
+{
+	struct pmc_hw *phw;
+
+	KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
+	    ("[ibs,%d] illegal CPU %d", __LINE__, cpu));
+	KASSERT(ri >= 0 && ri < IBS_NPMCS,
+	    ("[ibs,%d] row-index %d out of range", __LINE__, ri));
+
+	phw = &ibs_pcpu[cpu]->pc_ibspmcs[ri];
+
+	if (ri == IBS_PMC_FETCH) {
+		strlcpy(pi->pm_name, "IBS-FETCH", sizeof(pi->pm_name));
+		pi->pm_class = PMC_CLASS_IBS;
+		pi->pm_enabled = true;
+		*ppmc          = phw->phw_pmc;
+	} else {
+		strlcpy(pi->pm_name, "IBS-OP", sizeof(pi->pm_name));
+		pi->pm_class = PMC_CLASS_IBS;
+		pi->pm_enabled = true;
+		*ppmc          = phw->phw_pmc;
+	}
+
+	return (0);
+}
+
+/*
+ * Processor-dependent initialization.
+ */
+static int
+ibs_pcpu_init(struct pmc_mdep *md, int cpu)
+{
+	struct ibs_cpu *pac;
+	struct pmc_cpu *pc;
+	struct pmc_hw  *phw;
+	int first_ri, n;
+
+	KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
+	    ("[ibs,%d] insane cpu number %d", __LINE__, cpu));
+
+	PMCDBG1(MDP, INI, 1, "ibs-init cpu=%d", cpu);
+
+	ibs_pcpu[cpu] = pac = malloc(sizeof(struct ibs_cpu), M_PMC,
+	    M_WAITOK | M_ZERO);
+
+	/*
+	 * Set the content of the hardware descriptors to a known
+	 * state and initialize pointers in the MI per-cpu descriptor.
+	 */
+	pc = pmc_pcpu[cpu];
+	first_ri = md->pmd_classdep[PMC_MDEP_CLASS_INDEX_IBS].pcd_ri;
+
+	KASSERT(pc != NULL, ("[ibs,%d] NULL per-cpu pointer", __LINE__));
+
+	for (n = 0, phw = pac->pc_ibspmcs; n < IBS_NPMCS; n++, phw++) {
+		phw->phw_state = PMC_PHW_FLAG_IS_ENABLED |
+		    PMC_PHW_CPU_TO_STATE(cpu) | PMC_PHW_INDEX_TO_STATE(n);
+		phw->phw_pmc = NULL;
+		pc->pc_hwpmcs[n + first_ri] = phw;
+	}
+
+	return (0);
+}
+
+/*
+ * Processor-dependent cleanup prior to the KLD being unloaded.
+ */
+static int
+ibs_pcpu_fini(struct pmc_mdep *md, int cpu)
+{
+	struct ibs_cpu *pac;
+	struct pmc_cpu *pc;
+	int first_ri, i;
+
+	KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
+	    ("[ibs,%d] insane cpu number (%d)", __LINE__, cpu));
+
+	PMCDBG1(MDP, INI, 1, "ibs-cleanup cpu=%d", cpu);
+
+	/*
+	 * Turn off IBS.
+	 */
+	wrmsr(IBS_FETCH_CTL, 0);
+	wrmsr(IBS_OP_CTL, 0);
+
+	/*
+	 * Free up allocated space.
+	 */
+	if ((pac = ibs_pcpu[cpu]) == NULL)
+		return (0);
+
+	ibs_pcpu[cpu] = NULL;
+
+	pc = pmc_pcpu[cpu];
+	KASSERT(pc != NULL, ("[ibs,%d] NULL per-cpu state", __LINE__));
+
+	first_ri = md->pmd_classdep[PMC_MDEP_CLASS_INDEX_IBS].pcd_ri;
+
+	/*
+	 * Reset pointers in the MI 'per-cpu' state.
+	 */
+	for (i = 0; i < IBS_NPMCS; i++)
+		pc->pc_hwpmcs[i + first_ri] = NULL;
+
+	free(pac, M_PMC);
+
+	return (0);
+}
+
+/*
+ * Initialize ourselves.
+ */
+int
+pmc_ibs_initialize(struct pmc_mdep *pmc_mdep, int ncpus)
+{
+	u_int regs[4];
+	struct pmc_classdep *pcd;
+
+	/*
+	 * Allocate space for pointers to PMC HW descriptors and for
+	 * the MDEP structure used by MI code.
+	 */
+	ibs_pcpu = malloc(sizeof(struct ibs_cpu *) * pmc_cpu_max(), M_PMC,
+	    M_WAITOK | M_ZERO);
+
+	/* Initialize AMD IBS handling. */
+	pcd = &pmc_mdep->pmd_classdep[PMC_MDEP_CLASS_INDEX_IBS];
+
+	pcd->pcd_caps		= IBS_PMC_CAPS;
+	pcd->pcd_class		= PMC_CLASS_IBS;
+	pcd->pcd_num		= IBS_NPMCS;
+	pcd->pcd_ri		= pmc_mdep->pmd_npmc;
+	pcd->pcd_width		= 0;
+
+	pcd->pcd_allocate_pmc	= ibs_allocate_pmc;
+	pcd->pcd_config_pmc	= ibs_config_pmc;
+	pcd->pcd_describe	= ibs_describe;
+	pcd->pcd_get_config	= ibs_get_config;
+	pcd->pcd_pcpu_fini	= ibs_pcpu_fini;
+	pcd->pcd_pcpu_init	= ibs_pcpu_init;
+	pcd->pcd_release_pmc	= ibs_release_pmc;
+	pcd->pcd_start_pmc	= ibs_start_pmc;
+	pcd->pcd_stop_pmc	= ibs_stop_pmc;
+	pcd->pcd_read_pmc	= ibs_read_pmc;
+	pcd->pcd_write_pmc	= ibs_write_pmc;
+
+	pmc_mdep->pmd_npmc	+= IBS_NPMCS;
+
+	if (cpu_exthigh >= CPUID_IBSID) {
+		do_cpuid(CPUID_IBSID, regs);
+		ibs_features = regs[0];
+	} else {
+		ibs_features = 0;
+	}
+
+	PMCDBG0(MDP, INI, 0, "ibs-initialize");
+
+	return (0);
+}
+
+/*
+ * Finalization code for AMD CPUs.
+ */
+void
+pmc_ibs_finalize(struct pmc_mdep *md)
+{
+	PMCDBG0(MDP, INI, 1, "ibs-finalize");
+
+	for (int i = 0; i < pmc_cpu_max(); i++)
+		KASSERT(ibs_pcpu[i] == NULL,
+		    ("[ibs,%d] non-null pcpu cpu %d", __LINE__, i));
+
+	free(ibs_pcpu, M_PMC);
+	ibs_pcpu = NULL;
+}
diff --git a/sys/dev/hwpmc/hwpmc_ibs.h b/sys/dev/hwpmc/hwpmc_ibs.h
new file mode 100644
index 000000000000..4449b44c8368
--- /dev/null
+++ b/sys/dev/hwpmc/hwpmc_ibs.h
@@ -0,0 +1,176 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2026, Ali Jose Mashtizadeh
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef	_DEV_HWPMC_IBS_H_
+#define	_DEV_HWPMC_IBS_H_ 1
+
+#define	IBS_NPMCS			2
+#define	IBS_PMC_FETCH			0
+#define	IBS_PMC_OP			1
+
+/*
+ * All of the CPUID definitions come from AMD PPR Vol 1 for AMD Family 1Ah
+ * Model 02h C1 (57238) 2024-09-29 Revision 0.24.
+ */
+#define	CPUID_IBSID			0x8000001B
+#define	CPUID_IBSID_IBSFFV		0x00000001 /* IBS Feature Flags Valid */
+#define	CPUID_IBSID_FETCHSAM		0x00000002 /* IBS Fetch Sampling */
+#define	CPUID_IBSID_OPSAM		0x00000004 /* IBS Execution Sampling */
+#define	CPUID_IBSID_RDWROPCNT		0x00000008 /* RdWr Operationg Counter */
+#define	CPUID_IBSID_OPCNT		0x00000010 /* Operation Counter */
+#define	CPUID_IBSID_BRNTRGT		0x00000020 /* Branch Target Address */
+#define	CPUID_IBSID_OPCNTEXT		0x00000040 /* Extend Counter */
+#define	CPUID_IBSID_RIPINVALIDCHK	0x00000080 /* Invalid RIP Indication */
+#define	CPUID_IBSID_OPFUSE		0x00000010 /* Fused Branch Operation */
+#define	CPUID_IBSID_IBSFETCHCTLEXTD	0x00000020 /* IBS Fetch Control Ext */
+#define	CPUID_IBSID_IBSOPDATA4		0x00000040 /* IBS OP DATA4 */
+#define	CPUID_IBSID_ZEN4IBSEXTENSIONS	0x00000080 /* IBS Zen 4 Extensions */
+#define	CPUID_IBSID_IBSLOADLATENCYFILT	0x00000100 /* Load Latency Filtering */
+#define	CPUID_IBSID_IBSUPDTDDTLBSTATS	0x00080000 /* Simplified DTLB Stats */
+
+/*
+ * All of these definitions here come from AMD64 Architecture Programmer's
+ * Manual Volume 2: System Programming (24593) 2025-07-02 Version 3.43. with
+ * the following exceptions:
+ *
+ * OpData4 and fields come from the BKDG for AMD Family 15h Model 70-7Fh
+ * (55072) 2018-06-20 Revision 3.09.
+ */
+
+/* IBS MSRs */
+#define IBS_CTL				0xC001103A /* IBS Control */
+#define IBS_CTL_LVTOFFSETVALID		(1ULL << 8)
+#define IBS_CTL_LVTOFFSETMASK		0x0000000F
+
+/* IBS Fetch Control */
+#define IBS_FETCH_CTL			0xC0011030 /* IBS Fetch Control */
+#define IBS_FETCH_CTL_L3MISS		(1ULL << 61) /* L3 Cache Miss */
+#define IBS_FETCH_CTL_OPCACHEMISS	(1ULL << 60) /* Op Cache Miss */
+#define IBS_FETCH_CTL_L3MISSONLY	(1ULL << 59) /* L3 Miss Filtering */
+#define IBS_FETCH_CTL_RANDOMIZE		(1ULL << 57) /* Randomized Tagging */
+#define IBS_FETCH_CTL_L1TLBMISS		(1ULL << 55) /* L1 TLB Miss */
+// Page size 54:53
+#define IBS_FETCH_CTL_PHYSADDRVALID	(1ULL << 52) /* PHYSADDR Valid */
+#define IBS_FETCH_CTL_ICMISS		(1ULL << 51) /* Inst. Cache Miss */
+#define IBS_FETCH_CTL_COMPLETE		(1ULL << 50) /* Complete */
+#define IBS_FETCH_CTL_VALID		(1ULL << 49) /* Valid */
+#define IBS_FETCH_CTL_ENABLE		(1ULL << 48) /* Enable */
+#define IBS_FETCH_CTL_MAXCNTMASK	0x0000FFFFULL
+
+#define IBS_FETCH_CTL_TO_LAT(_c)	((_c >> 32) & 0x0000FFFF)
+
+#define IBS_FETCH_LINADDR		0xC0011031 /* Fetch Linear Address */
+#define IBS_FETCH_PHYSADDR		0xC0011032 /* Fetch Physical Address */
+#define IBS_FETCH_EXTCTL		0xC001103C /* Fetch Control Extended */
+
+#define PMC_MPIDX_FETCH_CTL		0
+#define PMC_MPIDX_FETCH_EXTCTL		1
+#define PMC_MPIDX_FETCH_LINADDR		2
+#define PMC_MPIDX_FETCH_PHYSADDR	3
+
+/* IBS Execution Control */
+#define IBS_OP_CTL			0xC0011033 /* IBS Execution Control */
+#define IBS_OP_CTL_COUNTERCONTROL	(1ULL << 19) /* Counter Control */
+#define IBS_OP_CTL_VALID		(1ULL << 18) /* Valid */
+#define IBS_OP_CTL_ENABLE		(1ULL << 17) /* Enable */
+#define IBS_OP_CTL_L3MISSONLY		(1ULL << 16) /* L3 Miss Filtering */
+#define IBS_OP_CTL_MAXCNTMASK		0x0000FFFFULL
+
+#define IBS_OP_RIP			0xC0011034 /* IBS Op RIP */
+#define IBS_OP_DATA			0xC0011035 /* IBS Op Data */
+#define IBS_OP_DATA_RIPINVALID		(1ULL << 38) /* RIP Invalid */
+#define IBS_OP_DATA_BRANCHRETIRED	(1ULL << 37) /* Branch Retired */
+#define IBS_OP_DATA_BRANCHMISPREDICTED	(1ULL << 36) /* Branch Mispredicted */
+#define IBS_OP_DATA_BRANCHTAKEN		(1ULL << 35) /* Branch Taken */
+#define IBS_OP_DATA_RETURN		(1ULL << 34) /* Return */
+
+#define IBS_OP_DATA2			0xC0011036 /* IBS Op Data 2 */
+#define IBS_OP_DATA3			0xC0011037 /* IBS Op Data 3 */
+#define IBS_OP_DATA3_DCPHYADDRVALID	(1ULL << 18) /* DC Physical Address */
+#define IBS_OP_DATA3_DCLINADDRVALID	(1ULL << 17) /* DC Linear Address */
+#define IBS_OP_DATA3_LOCKEDOP		(1ULL << 15) /* DC Locked Op */
+#define IBS_OP_DATA3_UCMEMACCESS	(1ULL << 14) /* DC UC Memory Access */
+#define IBS_OP_DATA3_WCMEMACCESS	(1ULL << 13) /* DC WC Memory Access */
+#define IBS_OP_DATA3_DCMISALIGN		(1ULL << 8)  /* DC Misaligned Access */
+#define IBS_OP_DATA3_DCMISS		(1ULL << 7)  /* DC Miss */
+#define IBS_OP_DATA3_DCL1TLBHIT1G	(1ULL << 5)  /* DC L1 TLB Hit 1-GB */
+#define IBS_OP_DATA3_DCL1TLBHIT2M	(1ULL << 4)  /* DC L1 TLB Hit 2-MB */
+#define IBS_OP_DATA3_DCL1TLBMISS	(1ULL << 2)  /* DC L1 TLB Miss */
+#define IBS_OP_DATA3_STORE		(1ULL << 1)  /* Store */
+#define IBS_OP_DATA3_LOAD		(1ULL << 0)  /* Load */
+#define IBS_OP_DATA3_TO_DCLAT(_c)	((_c >> 32) & 0x0000FFFF)
+
+#define IBS_OP_DC_LINADDR		0xC0011038 /* IBS DC Linear Address */
+#define IBS_OP_DC_PHYSADDR		0xC0011039 /* IBS DC Physical Address */
+#define IBS_TGT_RIP			0xC001103B /* IBS Branch Target */
+#define IBS_OP_DATA4			0xC001103D /* IBS Op Data 4 */
+#define IBS_OP_DATA4_LDRESYNC		(1ULL << 0)  /* Load Resync */
+
+#define PMC_MPIDX_OP_CTL		0
+#define PMC_MPIDX_OP_RIP		1
+#define PMC_MPIDX_OP_DATA		2
+#define PMC_MPIDX_OP_DATA2		3
+#define PMC_MPIDX_OP_DATA3		4
+#define PMC_MPIDX_OP_DC_LINADDR		5
+#define PMC_MPIDX_OP_DC_PHYSADDR	6
+#define PMC_MPIDX_OP_TGT_RIP		7
+#define PMC_MPIDX_OP_DATA4		8
+
+/*
+ * IBS data is encoded as using the multipart flag in the existing callchain
+ * structure.  The PMC ID number tells you if the sample contains a fetch or an
+ * op sample.  The available payload will be encoded in the MSR order with a
+ * variable length.
+ */
+
+struct pmc_md_ibs_op_pmcallocate {
+	uint32_t	ibs_flag;
+	uint32_t	ibs_type;
+	uint64_t	ibs_ctl;
+	uint64_t	ibs_ctl2;
+};
+
+#ifdef _KERNEL
+
+/* MD extension for 'struct pmc' */
+struct pmc_md_ibs_pmc {
+	uint32_t	ibs_flag;
+	uint32_t	ibs_type;
+	uint64_t	ibs_ctl;
+	uint64_t	ibs_ctl2;
+};
+
+#define IBS_PMC_CAPS			(PMC_CAP_INTERRUPT | PMC_CAP_SYSTEM | \
+	PMC_CAP_EDGE | PMC_CAP_QUALIFIER | PMC_CAP_PRECISE)
+
+int	pmc_ibs_initialize(struct pmc_mdep *md, int ncpu);
+void	pmc_ibs_finalize(struct pmc_mdep *md);
+int	pmc_ibs_intr(struct trapframe *tf);
+
+#endif /* _KERNEL */
+#endif /* _DEV_HWPMC_IBS_H_ */
diff --git a/sys/dev/hwpmc/hwpmc_mod.c b/sys/dev/hwpmc/hwpmc_mod.c
index a6a6ae68996c..1fa021429c5a 100644
--- a/sys/dev/hwpmc/hwpmc_mod.c
+++ b/sys/dev/hwpmc/hwpmc_mod.c
@@ -198,9 +198,15 @@ static int	pmc_debugflags_sysctl_handler(SYSCTL_HANDLER_ARGS);
 static int	pmc_debugflags_parse(char *newstr, char *fence);
 #endif
 
+static bool	pmc_is_multipart(struct pmc_sample *ps);
+static void	pmc_multipart_add(struct pmc_sample *ps, int type,
+    int length);
+static void	pmc_multipart_copydata(struct pmc_sample *ps,
+    struct pmc_multipart *mp);
+
 static int	load(struct module *module, int cmd, void *arg);
 static int	pmc_add_sample(ring_type_t ring, struct pmc *pm,
-    struct trapframe *tf);
+    struct trapframe *tf, struct pmc_multipart *mp);
 static void	pmc_add_thread_descriptors_from_proc(struct proc *p,
     struct pmc_process *pp);
 static int	pmc_attach_process(struct proc *p, struct pmc *pm);
@@ -4587,6 +4593,53 @@ pmc_post_callchain_callback(void)
 	return;
 }
 
+static bool
+pmc_is_multipart(struct pmc_sample *ps)
+{
+	return ((ps->ps_flags & PMC_CC_F_MULTIPART) != 0);
+}
+
+static void
+pmc_multipart_add(struct pmc_sample *ps, int type, int length)
+{
+	int i;
+	uint8_t *hdr;
+
+	MPASS(ps->ps_pc != NULL);
+	MPASS(ps->ps_nsamples_actual != 0);
+
+	hdr = (uint8_t *)ps->ps_pc;
+
+	for (i = 0; i < PMC_MULTIPART_HEADER_ENTRIES; i++) {
+		if (hdr[2 * i] == PMC_CC_MULTIPART_NONE) {
+			hdr[2 * i] = type;
+			hdr[2 * i + 1] = length;
+			ps->ps_nsamples_actual += length;
+			return;
+		}
+	}
+
+	KASSERT(false, ("Too many parts in the multipart header!"));
+}
+
+static void
+pmc_multipart_copydata(struct pmc_sample *ps, struct pmc_multipart *mp)
+{
+	int i, scale;
+	uint64_t *ps_pc;
+
+	MPASS(ps->ps_pc != NULL);
+	MPASS(ps->ps_nsamples_actual != 0);
+
+	ps_pc = (uint64_t *)ps->ps_pc;
+
+	for (i = 0; i < mp->pl_length; i++)
+		ps_pc[i + 1] = mp->pl_mpdata[i];
+
+	scale = sizeof(uint64_t) / sizeof(uintptr_t);
+	pmc_multipart_add(ps, mp->pl_type, scale * mp->pl_length);
+}
+
 /*
  * Find a free slot in the per-cpu array of samples and capture the
  * current callchain there.  If a sample was successfully added, a bit
@@ -4597,7 +4650,8 @@ pmc_post_callchain_callback(void)
  * use any of the locking primitives supplied by the OS.
  */
 static int
-pmc_add_sample(ring_type_t ring, struct pmc *pm, struct trapframe *tf)
+pmc_add_sample(ring_type_t ring, struct pmc *pm, struct trapframe *tf,
+    struct pmc_multipart *mp)
 {
 	struct pmc_sample *ps;
 	struct pmc_samplebuffer *psb;
@@ -4641,21 +4695,33 @@ pmc_add_sample(ring_type_t ring, struct pmc *pm, struct trapframe *tf)
 	ps->ps_ticks = ticks;
 	ps->ps_cpu = cpu;
 	ps->ps_flags = inuserspace ? PMC_CC_F_USERSPACE : 0;
+	ps->ps_nsamples_actual = 0;
 
 	callchaindepth = (pm->pm_flags & PMC_F_CALLCHAIN) ?
 	    pmc_callchaindepth : 1;
 
 	MPASS(ps->ps_pc != NULL);
+
+	if (mp != NULL) {
+		/* Set multipart flag, clear header and copy data */
+		ps->ps_flags |= PMC_CC_F_MULTIPART;
+		ps->ps_pc[0] = 0;
+		ps->ps_nsamples_actual = 1;
+		pmc_multipart_copydata(ps, mp);
+	}
+
 	if (callchaindepth == 1) {
-		ps->ps_pc[0] = PMC_TRAPFRAME_TO_PC(tf);
+		ps->ps_pc[ps->ps_nsamples_actual] = PMC_TRAPFRAME_TO_PC(tf);
 	} else {
 		/*
 		 * Kernel stack traversals can be done immediately, while we
 		 * defer to an AST for user space traversals.
 		 */
 		if (!inuserspace) {
-			callchaindepth = pmc_save_kernel_callchain(ps->ps_pc,
-			    callchaindepth, tf);
+			callchaindepth = pmc_save_kernel_callchain(
+			    ps->ps_pc + ps->ps_nsamples_actual,
+			    callchaindepth - ps->ps_nsamples_actual, tf);
+			callchaindepth += ps->ps_nsamples_actual;
 		} else {
 			pmc_post_callchain_callback();
 			callchaindepth = PMC_USER_CALLCHAIN_PENDING;
@@ -4664,7 +4730,7 @@ pmc_add_sample(ring_type_t ring, struct pmc *pm, struct trapframe *tf)
 
 	ps->ps_nsamples = callchaindepth; /* mark entry as in-use */
 	if (ring == PMC_UR) {
-		ps->ps_nsamples_actual = callchaindepth;
+		ps->ps_nsamples_actual = ps->ps_nsamples;
 		ps->ps_nsamples = PMC_USER_CALLCHAIN_PENDING;
 	}
 
@@ -4690,7 +4756,8 @@ done:
  * locking primitives supplied by the OS.
  */
 int
-pmc_process_interrupt(int ring, struct pmc *pm, struct trapframe *tf)
+pmc_process_interrupt_mp(int ring, struct pmc *pm, struct trapframe *tf,
+    struct pmc_multipart *mp)
 {
 	struct thread *td;
 
@@ -4698,9 +4765,15 @@ pmc_process_interrupt(int ring, struct pmc *pm, struct trapframe *tf)
 	if ((pm->pm_flags & PMC_F_USERCALLCHAIN) &&
 	    (td->td_proc->p_flag & P_KPROC) == 0 && !TRAPF_USERMODE(tf)) {
 		atomic_add_int(&td->td_pmcpend, 1);
-		return (pmc_add_sample(PMC_UR, pm, tf));
+		return (pmc_add_sample(PMC_UR, pm, tf, mp));
 	}
-	return (pmc_add_sample(ring, pm, tf));
+	return (pmc_add_sample(ring, pm, tf, mp));
+}
+
+int
+pmc_process_interrupt(int ring, struct pmc *pm, struct trapframe *tf)
+{
+	return (pmc_process_interrupt_mp(ring, pm, tf, NULL));
 }
 
 /*
@@ -4763,10 +4836,9 @@ restart:
 		    (uintmax_t)counter_u64_fetch(pm->pm_runcount)));
 
 		if (ring == PMC_UR) {
-			nsamples = ps->ps_nsamples_actual;
 			counter_u64_add(pmc_stats.pm_merges, 1);
-		} else
-			nsamples = 0;
+		}
+		nsamples = ps->ps_nsamples_actual;
 
 		/*
 		 * Retrieve the callchain and mark the sample buffer
diff --git a/sys/dev/hwpmc/pmc_events.h b/sys/dev/hwpmc/pmc_events.h
index ab157cb05dcf..b22ec1919b32 100644
--- a/sys/dev/hwpmc/pmc_events.h
+++ b/sys/dev/hwpmc/pmc_events.h
@@ -149,6 +149,15 @@ __PMC_EV(K8, NB_HT_BUS2_BANDWIDTH)
 #define	PMC_EV_K8_FIRST		PMC_EV_K8_FP_DISPATCHED_FPU_OPS
 #define	PMC_EV_K8_LAST		PMC_EV_K8_NB_HT_BUS2_BANDWIDTH
 
+/* AMD IBS PMCs */
+
+#define	__PMC_EV_IBS()							\
+__PMC_EV(IBS, FETCH)							\
+__PMC_EV(IBS, OP)
+
+#define	PMC_EV_IBS_FIRST	PMC_EV_IBS_FETCH
+#define	PMC_EV_IBS_LAST		PMC_EV_IBS_OP
+
 /*
  * Events supported by Intel architectural fixed function counters,
  * from the "Intel 64 and IA-32 Architectures Software Developer's
@@ -2398,7 +2407,7 @@ __PMC_EV_ALIAS("unhalted-reference-cycles", IAF_CPU_CLK_UNHALTED_REF)
  * START	#EVENTS		DESCRIPTION
  * 0		0x1000		Reserved
  * 0x1000	0x0001		TSC
- * 0x2000	0x0080		free (was AMD K7 events)
+ * 0x2000	0x0080		AMD IBS (was AMD K7 events)
  * 0x2080	0x0100		AMD K8 events
  * 0x10000	0x0080		INTEL architectural fixed-function events
  * 0x10080	0x0F80		free (was INTEL architectural programmable events)
@@ -2424,6 +2433,8 @@ __PMC_EV_ALIAS("unhalted-reference-cycles", IAF_CPU_CLK_UNHALTED_REF)
 #define	__PMC_EVENTS()					\
 	__PMC_EV_BLOCK(TSC,		0x01000)	\
 	__PMC_EV_TSC()					\
+	__PMC_EV_BLOCK(IBS,		0x02000)	\
+	__PMC_EV_IBS()					\
 	__PMC_EV_BLOCK(K8,		0x02080)	\
 	__PMC_EV_K8()					\
 	__PMC_EV_BLOCK(IAF,		0x10000)	\
diff --git a/sys/i386/include/pmc_mdep.h b/sys/i386/include/pmc_mdep.h
index 77b57b3163f2..31eded611a1e 100644
--- a/sys/i386/include/pmc_mdep.h
+++ b/sys/i386/include/pmc_mdep.h
@@ -43,6 +43,7 @@ struct pmc_mdep;
  * TSC		The timestamp counter
  * K7		AMD Athlon XP/MP and other 32 bit processors.
  * K8		AMD Athlon64 and Opteron PMCs in 32 bit mode.
+ * IBS		AMD IBS
  * IAP		Intel Core/Core2/Atom programmable PMCs.
  * IAF		Intel fixed-function PMCs.
  * UCP		Intel Uncore programmable PMCs.
@@ -50,6 +51,7 @@ struct pmc_mdep;
  */
 
 #include <dev/hwpmc/hwpmc_amd.h> /* K7 and K8 */
+#include <dev/hwpmc/hwpmc_ibs.h>
 #include <dev/hwpmc/hwpmc_core.h>
 #include <dev/hwpmc/hwpmc_tsc.h>
 #include <dev/hwpmc/hwpmc_uncore.h>
@@ -62,6 +64,7 @@ struct pmc_mdep;
 #define	PMC_MDEP_CLASS_INDEX_TSC	1
 #define	PMC_MDEP_CLASS_INDEX_K7		2
 #define	PMC_MDEP_CLASS_INDEX_K8		2
+#define	PMC_MDEP_CLASS_INDEX_IBS	3
 #define	PMC_MDEP_CLASS_INDEX_IAP	2
 #define	PMC_MDEP_CLASS_INDEX_IAF	3
 #define	PMC_MDEP_CLASS_INDEX_UCP	4
@@ -73,6 +76,7 @@ struct pmc_mdep;
 
 union pmc_md_op_pmcallocate  {
 	struct pmc_md_amd_op_pmcallocate	pm_amd;
+	struct pmc_md_ibs_op_pmcallocate	pm_ibs;
 	struct pmc_md_iap_op_pmcallocate	pm_iap;
 	struct pmc_md_ucf_op_pmcallocate	pm_ucf;
 	struct pmc_md_ucp_op_pmcallocate	pm_ucp;
@@ -88,6 +92,7 @@ union pmc_md_op_pmcallocate  {
 /* MD extension for 'struct pmc' */
 union pmc_md_pmc  {
 	struct pmc_md_amd_pmc	pm_amd;
+	struct pmc_md_ibs_pmc	pm_ibs;
 	struct pmc_md_iaf_pmc	pm_iaf;
 	struct pmc_md_iap_pmc	pm_iap;
 	struct pmc_md_ucf_pmc	pm_ucf;
diff --git a/sys/modules/hwpmc/Makefile b/sys/modules/hwpmc/Makefile
index 812e3fbf182c..d13f52009600 100644
--- a/sys/modules/hwpmc/Makefile
+++ b/sys/modules/hwpmc/Makefile
@@ -16,7 +16,7 @@ SRCS.DEV_ACPI+=	hwpmc_dmc620.c pmu_dmc620.c
 .endif
 
 .if ${MACHINE_CPUARCH} == "amd64"
-SRCS+=	hwpmc_amd.c hwpmc_core.c hwpmc_intel.c hwpmc_tsc.c
+SRCS+=	hwpmc_amd.c hwpmc_core.c hwpmc_ibs.c hwpmc_intel.c hwpmc_tsc.c
 SRCS+=	hwpmc_x86.c hwpmc_uncore.c
 .endif
 
@@ -29,7 +29,7 @@ SRCS+= hwpmc_armv7.c
 .endif
 
 .if ${MACHINE_CPUARCH} == "i386"
-SRCS+=	hwpmc_amd.c hwpmc_core.c hwpmc_intel.c
+SRCS+=	hwpmc_amd.c hwpmc_core.c hwpmc_ibs.c hwpmc_intel.c
 SRCS+=	hwpmc_tsc.c hwpmc_x86.c hwpmc_uncore.c
 .endif
 
diff --git a/sys/sys/pmc.h b/sys/sys/pmc.h
index 12b8ddcb156f..28484eed187e 100644
--- a/sys/sys/pmc.h
+++ b/sys/sys/pmc.h
@@ -141,6 +141,7 @@ enum pmc_cputype {
 #define	__PMC_CLASSES()								\
     __PMC_CLASS(TSC,		0x00,	"CPU Timestamp counter")		\
     __PMC_CLASS(K8,		0x02,	"AMD K8 performance counters")		\
+    __PMC_CLASS(IBS,		0x03,	"AMD IBS performance counters")		\
     __PMC_CLASS(IAF,		0x06,	"Intel Core2/Atom, fixed function")	\
     __PMC_CLASS(IAP,		0x07,	"Intel Core...Atom, programmable")	\
     __PMC_CLASS(UCF,		0x08,	"Intel Uncore fixed function")		\
@@ -386,6 +387,7 @@ enum pmc_ops {
 #define	PMC_CALLCHAIN_DEPTH_MAX	512
 
 #define	PMC_CC_F_USERSPACE	0x01	   /*userspace callchain*/
+#define	PMC_CC_F_MULTIPART	0x02	   /*multipart data*/
 
 /*
  * Cookies used to denote allocated PMCs, and the values of PMCs.
@@ -960,6 +962,18 @@ struct pmc_samplebuffer {
 #define PMC_PROD_SAMPLE(psb)					\
 	(&(psb)->ps_samples[(psb)->ps_prodidx & pmc_sample_mask])
 
+
+/*
+ * struct pmc_multipart
+ *
+ * Multipart payload
+ */
+struct pmc_multipart {
+	char			pl_type;
+	char			pl_length;
+	uint64_t		pl_mpdata[10];
+};
+
 /*
  * struct pmc_cpustate
  *
@@ -1226,7 +1240,10 @@ MALLOC_DECLARE(M_PMC);
 struct pmc_mdep *pmc_md_initialize(void);	/* MD init function */
 void	pmc_md_finalize(struct pmc_mdep *_md);	/* MD fini function */
 int	pmc_getrowdisp(int _ri);
-int	pmc_process_interrupt(int _ring, struct pmc *_pm, struct trapframe *_tf);
+int	pmc_process_interrupt_mp(int _ring, struct pmc *_pm,
+    struct trapframe *_tf, struct pmc_multipart *mp);
+int	pmc_process_interrupt(int _ring, struct pmc *_pm,
+    struct trapframe *_tf);
 int	pmc_save_kernel_callchain(uintptr_t *_cc, int _maxsamples,
     struct trapframe *_tf);
 int	pmc_save_user_callchain(uintptr_t *_cc, int _maxsamples,
diff --git a/sys/sys/pmclog.h b/sys/sys/pmclog.h
index 3f79f17f306c..362792ae9ad1 100644
--- a/sys/sys/pmclog.h
+++ b/sys/sys/pmclog.h
@@ -125,6 +125,20 @@ struct pmclog_callchain {
 #define	PMC_CALLCHAIN_TO_CPUFLAGS(CPU,FLAGS)	\
 	(((CPU) << 16) | ((FLAGS) & 0xFFFF))
 
+/*
+ * If the multipart flag is set, then pl_pc contains multiple data types.  The
+ * first 8 bytes is a header made up of a 1 byte type and 1 byte length that
+ * describes the use of the remaining pl_pc array.
+ */
+
+#define PMC_MULTIPART_HEADER_LENGTH	8
+#define PMC_MULTIPART_HEADER_ENTRIES	4
+
+#define	PMC_CC_MULTIPART_NONE		0
+#define	PMC_CC_MULTIPART_CALLCHAIN	1
+#define	PMC_CC_MULTIPART_IBS_FETCH	2
+#define	PMC_CC_MULTIPART_IBS_OP		3
+
 struct pmclog_closelog {
 	PMCLOG_ENTRY_HEADER
 };
diff --git a/sys/x86/x86/local_apic.c b/sys/x86/x86/local_apic.c
index 54026f83dc15..8a8fb8ef41f6 100644
--- a/sys/x86/x86/local_apic.c
+++ b/sys/x86/x86/local_apic.c
@@ -230,11 +230,11 @@ static struct lvt elvts[] = {
 		.lvt_edgetrigger = 1,
 		.lvt_activehi = 1,
 		.lvt_masked = 1,
-		.lvt_active = 0,
-		.lvt_mode = APIC_LVT_DM_FIXED,
+		.lvt_active = 1,
+		.lvt_mode = APIC_LVT_DM_NMI,
 		.lvt_vector = 0,
 		.lvt_reg = LAPIC_EXT_LVT0,
-		.lvt_desc = "ELVT0",
+		.lvt_desc = "IBS",
 	},
 	[APIC_ELVT_MCA] = {
 		.lvt_edgetrigger = 1,
@@ -528,7 +528,10 @@ elvt_mode(struct lapic *la, u_int idx, uint32_t value)
 	KASSERT(idx <= APIC_ELVT_MAX,
 	    ("%s: idx %u out of range", __func__, idx));
 
-	elvt = &la->la_elvts[idx];
+	if (la->la_elvts[idx].lvt_active)
+	    elvt = &la->la_elvts[idx];
+	else
+	    elvt = &elvts[idx];
 	KASSERT(elvt->lvt_active, ("%s: ELVT%u is not active", __func__, idx));
 	KASSERT(elvt->lvt_edgetrigger,
 	    ("%s: ELVT%u is not edge triggered", __func__, idx));
@@ -963,9 +966,16 @@ lapic_reenable_pcint(void)
 
 	if (refcount_load(&pcint_refcnt) == 0)
 		return;
+
 	value = lapic_read32(LAPIC_LVT_PCINT);
 	value &= ~APIC_LVT_M;
 	lapic_write32(LAPIC_LVT_PCINT, value);
+
+	if ((amd_feature2 & AMDID2_IBS) != 0) {
+		value = lapic_read32(LAPIC_EXT_LVT0);
+		value &= ~APIC_LVT_M;
+		lapic_write32(LAPIC_EXT_LVT0, value);
+	}
 }
 
 static void
@@ -976,6 +986,11 @@ lapic_update_pcint(void *dummy)
 	la = &lapics[lapic_id()];
 	lapic_write32(LAPIC_LVT_PCINT, lvt_mode(la, APIC_LVT_PMC,
 	    lapic_read32(LAPIC_LVT_PCINT)));
+
+	if ((amd_feature2 & AMDID2_IBS) != 0) {
+		lapic_write32(LAPIC_EXT_LVT0, elvt_mode(la, APIC_ELVT_IBS,
+		    lapic_read32(LAPIC_EXT_LVT0)));
+	}
 }
 
 void
@@ -1022,6 +1037,9 @@ lapic_enable_pcint(void)
 		return (1);
 	lvts[APIC_LVT_PMC].lvt_masked = 0;
 
+	if ((amd_feature2 & AMDID2_IBS) != 0)
+		elvts[APIC_ELVT_IBS].lvt_masked = 0;
+
 	MPASS(mp_ncpus == 1 || smp_started);
 	smp_rendezvous(NULL, lapic_update_pcint, NULL, NULL);
 	return (1);
@@ -1045,6 +1063,7 @@ lapic_disable_pcint(void)
 	if (!refcount_release(&pcint_refcnt))
 		return;
 	lvts[APIC_LVT_PMC].lvt_masked = 1;
+	elvts[APIC_ELVT_IBS].lvt_masked = 1;
 
 #ifdef SMP
 	/* The APs should always be started when hwpmc is unloaded. */
diff --git a/usr.sbin/pmcstat/pmcstat_log.c b/usr.sbin/pmcstat/pmcstat_log.c
index c8fc414f6214..db9cbfabd9da 100644
--- a/usr.sbin/pmcstat/pmcstat_log.c
+++ b/usr.sbin/pmcstat/pmcstat_log.c
@@ -56,6 +56,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <gelf.h>
+#include <inttypes.h>
 #include <libgen.h>
 #include <limits.h>
 #include <netdb.h>
@@ -367,6 +368,97 @@ pmcstat_pmcindex_to_pmcr(int pmcin)
 	return NULL;
 }
 
+#if defined(__amd64__) || defined(__i386__)
+static void
+pmcstat_print_ibs_fetch(struct pmclog_ev_callchain *cc, int offset)
+{
+	uint64_t *ibsbuf = (uint64_t *)&cc->pl_pc[offset];
+	uint64_t ctl;
+
+	ctl = ibsbuf[PMC_MPIDX_FETCH_CTL];
+	PMCSTAT_PRINT_ENTRY("ibs-fetch", "%s%s%s%s",
+	    (ctl & IBS_FETCH_CTL_ICMISS) ? "icmiss " : "",
+	    (ctl & IBS_FETCH_CTL_L1TLBMISS) ? "l1tlbmiss " : "",
+	    (ctl & IBS_FETCH_CTL_OPCACHEMISS) ? "opcachemiss " : "",
+	    (ctl & IBS_FETCH_CTL_L3MISS) ? "l3miss" : "");
+	PMCSTAT_PRINT_ENTRY("ibs-fetch", "Latency %" PRIu64,
+	    IBS_FETCH_CTL_TO_LAT(ctl));
+	PMCSTAT_PRINT_ENTRY("IBS", "Address %" PRIx64,
+	    ibsbuf[PMC_MPIDX_FETCH_LINADDR]);
+	if ((ctl & IBS_FETCH_CTL_PHYSADDRVALID) != 0) {
+		PMCSTAT_PRINT_ENTRY("IBS", "Physical Address %" PRIx64,
+		    ibsbuf[PMC_MPIDX_FETCH_PHYSADDR]);
+	}
+}
+
+static void
+pmcstat_print_ibs_op(struct pmclog_ev_callchain *cc, int offset)
+{
+	uint64_t *ibsbuf = (uint64_t *)&cc->pl_pc[offset];
+	uint64_t data, data3;
+
+	data = ibsbuf[PMC_MPIDX_OP_DATA];
+	data3 = ibsbuf[PMC_MPIDX_OP_DATA3];
+
+	if ((data & IBS_OP_DATA_RIPINVALID) == 0) {
+		PMCSTAT_PRINT_ENTRY("ibs-op", "RIP %" PRIx64,
+		    ibsbuf[PMC_MPIDX_OP_RIP]);
+	}
+	PMCSTAT_PRINT_ENTRY("ibs-op", "%s%s%s%s",
+	    (data & IBS_OP_DATA_BRANCHRETIRED) ? "branchretired " : "",
+	    (data & IBS_OP_DATA_BRANCHMISPREDICTED) ? "branchmispredicted " : "",
+	    (data & IBS_OP_DATA_BRANCHTAKEN) ? "branchtaken " : "",
+	    (data & IBS_OP_DATA_RETURN) ? "return" : "");
+	PMCSTAT_PRINT_ENTRY("ibs-op", "%s%s%s%s%s",
+	    (data3 & IBS_OP_DATA3_LOAD) ? "load " : "",
+	    (data3 & IBS_OP_DATA3_STORE) ? "store " : "",
+	    (data3 & IBS_OP_DATA3_LOCKEDOP) ? "lock " : "",
+	    (data3 & IBS_OP_DATA3_DCL1TLBMISS) ? "l1tlbmiss " : "",
+	    (data3 & IBS_OP_DATA3_DCMISS) ? "dcmiss " : "");
+	PMCSTAT_PRINT_ENTRY("ibs-op", "Latency %" PRIu64,
+	    IBS_OP_DATA3_TO_DCLAT(data3));
+	if ((data3 & IBS_OP_DATA3_DCLINADDRVALID) != 0) {
+		PMCSTAT_PRINT_ENTRY("ibs-op", "Address %" PRIx64,
+		    ibsbuf[PMC_MPIDX_OP_DC_LINADDR]);
+	}
+	if ((data3 & IBS_OP_DATA3_DCPHYADDRVALID) != 0) {
+		PMCSTAT_PRINT_ENTRY("ibs-op", "Physical Address %" PRIx64,
+		    ibsbuf[PMC_MPIDX_OP_DC_PHYSADDR]);
+	}
+}
+#endif
+
+static int
+pmcstat_print_multipart(struct pmclog_ev_callchain *cc)
+{
+	int i;
+	uint8_t *hdr = (uint8_t *)&cc->pl_pc[0];
+	int offset = PMC_MULTIPART_HEADER_LENGTH / sizeof(uintptr_t);
+
+	for (i = 0; i < PMC_MULTIPART_HEADER_ENTRIES; i++) {
+		uint8_t type = hdr[2 * i];
+		uint8_t len = hdr[2 * i + 1];
+
+		if (type == PMC_CC_MULTIPART_NONE) {
+			break;
+		} else if (type == PMC_CC_MULTIPART_CALLCHAIN) {
+			return (offset);
+#if defined(__amd64__) || defined(__i386__)
+		} else if (type == PMC_CC_MULTIPART_IBS_FETCH) {
+			pmcstat_print_ibs_fetch(cc, offset);
+		} else if (type == PMC_CC_MULTIPART_IBS_OP) {
+			pmcstat_print_ibs_op(cc, offset);
+#endif
+		} else {
+			PMCSTAT_PRINT_ENTRY("unsupported multipart type!");
+		}
+
+		offset += len;
+	}
+
+	return (offset);
+}
+
 /*
  * Print log entries as text.
  */
@@ -388,7 +480,12 @@ pmcstat_print_log(void)
 				pl_cpuflags), ev.pl_u.pl_cc.pl_npc,
 			    PMC_CALLCHAIN_CPUFLAGS_TO_USERMODE(ev.pl_u.pl_cc.\
 			        pl_cpuflags) ? 'u' : 's');
-			for (npc = 0; npc < ev.pl_u.pl_cc.pl_npc; npc++)
+			if ((ev.pl_u.pl_cc.pl_cpuflags & PMC_CC_F_MULTIPART)
+			    != 0)
+				npc = pmcstat_print_multipart(&ev.pl_u.pl_cc);
+			else
+				npc = 0;
+			for (; npc < ev.pl_u.pl_cc.pl_npc; npc++)
 				PMCSTAT_PRINT_ENTRY("...", "%p",
 				    (void *) ev.pl_u.pl_cc.pl_pc[npc]);
 			break;