[PATCH] x86 performance counters driver 3.0-pre2 for 2.5.44: [2/4] x86 support

* [PATCH] x86 performance counters driver 3.0-pre2 for 2.5.44: [2/4] x86 support
@ 2002-10-24 15:00 Mikael Pettersson
  2002-10-24 15:49 ` Andi Kleen
  0 siblings, 1 reply; 4+ messages in thread
From: Mikael Pettersson @ 2002-10-24 15:00 UTC (permalink / raw)
  To: linux-kernel

Here is perfctr-3.0-pre2 for 2.5.44. This is the 2.5-ready version
of the Linux/x86 performance-monitoring counters kernel extension.
Please consider it for inclusion in 2.5/2.6.

This is part 2 of 4: adding x86 support files. The kernel will still
compile with this patch set applied.

/Mikael

 drivers/perfctr/x86.c        | 1534 +++++++++++++++++++++++++++++++++++++++++++
 drivers/perfctr/x86_compat.c |   38 +
 drivers/perfctr/x86_compat.h |   38 +
 include/asm-i386/perfctr.h   |  157 ++++
 4 files changed, 1767 insertions(+)

diff -ruN linux-2.5.44/drivers/perfctr/x86.c linux-2.5.44.perfctr-3.0-pre2/drivers/perfctr/x86.c

--- linux-2.5.44/drivers/perfctr/x86.c	Thu Jan  1 01:00:00 1970
+++ linux-2.5.44.perfctr-3.0-pre2/drivers/perfctr/x86.c	Wed Oct 23 20:47:15 2002
@@ -0,0 +1,1534 @@
+/* $Id: x86.c,v 1.69 2002/10/20 21:52:12 mikpe Exp $
+ * x86 performance-monitoring counters driver.
+ *
+ * Copyright (C) 1999-2002  Mikael Pettersson
+ */
+#include <linux/config.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/perfctr.h>
+
+#include <asm/msr.h>
+#undef MSR_P6_PERFCTR0
+#include <asm/fixmap.h>	/* for 2.4 */
+#include <asm/apic.h>
+struct hw_interrupt_type;
+#include <asm/hw_irq.h>
+
+#include "compat.h"
+#include "x86_compat.h"
+
+/* Support for lazy evntsel and perfctr MSR updates. */
+struct per_cpu_cache {	/* roughly a subset of perfctr_cpu_state */
+	union {
+		unsigned int p5_cesr;
+		unsigned int id;	/* cache owner id */
+	} k1;
+	struct {
+		/* NOTE: these caches have physical indices, not virtual */
+		unsigned int evntsel[18];
+		unsigned int escr[0x3E2-0x3A0];
+		unsigned int pebs_enable;
+		unsigned int pebs_matrix_vert;
+	} control;
+} __attribute__((__aligned__(SMP_CACHE_BYTES)));
+static struct per_cpu_cache per_cpu_cache[NR_CPUS] __cacheline_aligned;
+
+/* Intel P5, Cyrix 6x86MX/MII/III, Centaur WinChip C6/2/3 */
+#define MSR_P5_CESR		0x11
+#define MSR_P5_CTR0		0x12		/* .. 0x13 */
+#define P5_CESR_CPL		0x00C0
+#define P5_CESR_RESERVED	(~0x01FF)
+#define MII_CESR_RESERVED	(~0x05FF)
+#define C6_CESR_RESERVED	(~0x00FF)
+
+/* Intel P6, VIA C3 */
+#define MSR_P6_PERFCTR0		0xC1		/* .. 0xC2 */
+#define MSR_P6_EVNTSEL0		0x186		/* .. 0x187 */
+#define P6_EVNTSEL_ENABLE	0x00400000
+#define P6_EVNTSEL_INT		0x00100000
+#define P6_EVNTSEL_CPL		0x00030000
+#define P6_EVNTSEL_RESERVED	0x00280000
+#define VC3_EVNTSEL1_RESERVED	(~0x1FF)
+
+/* AMD K7 */
+#define MSR_K7_EVNTSEL0		0xC0010000	/* .. 0xC0010003 */
+#define MSR_K7_PERFCTR0		0xC0010004	/* .. 0xC0010007 */
+
+/* Intel P4 */
+#define MSR_P4_MISC_ENABLE	0x1A0
+#define MSR_P4_MISC_ENABLE_PERF_AVAIL (1<<7)	/* read-only status bit */
+#define MSR_P4_MISC_ENABLE_PEBS_UNAVAIL (1<<12) /* read-only status bit */
+#define MSR_P4_PERFCTR0		0x300		/* .. 0x311 */
+#define MSR_P4_CCCR0		0x360		/* .. 0x371 */
+#define MSR_P4_ESCR0		0x3A0		/* .. 0x3E1, with some gaps */
+
+#define MSR_P4_PEBS_ENABLE	0x3F1
+#define P4_PE_REPLAY_TAG_BITS	0x00000607
+#define P4_PE_UOP_TAG		0x01000000
+#define P4_PE_RESERVED		0xFEFFF9F8	/* only allow ReplayTagging */
+
+#define MSR_P4_PEBS_MATRIX_VERT	0x3F2
+#define P4_PMV_REPLAY_TAG_BITS	0x00000003
+#define P4_PMV_RESERVED		0xFFFFFFFC
+
+#define P4_CCCR_OVF		0x80000000
+#define P4_CCCR_CASCADE		0x40000000
+#define P4_CCCR_OVF_PMI_T1	0x08000000
+#define P4_CCCR_OVF_PMI_T0	0x04000000
+#define P4_CCCR_ACTIVE_THREAD	0x00030000
+#define P4_CCCR_ENABLE		0x00001000
+#define P4_CCCR_ESCR_SELECT(X)	(((X) >> 13) & 0x7)
+#define P4_CCCR_RESERVED	(0x30000FFF|P4_CCCR_OVF|P4_CCCR_OVF_PMI_T1)
+#define P4_CCCR_REQUIRED	P4_CCCR_ACTIVE_THREAD
+
+#define P4_ESCR_CPL_T1		0x00000003
+#define P4_ESCR_CPL_T0		0x0000000C	/* must be non-zero */
+#define P4_ESCR_TAG_ENABLE	0x00000010
+#define P4_ESCR_RESERVED	(0x80000000|P4_ESCR_CPL_T1)
+
+#define P4_FAST_RDPMC		0x80000000
+#define P4_MASK_FAST_RDPMC	0x0000001F	/* we only need low 5 bits */
+
+#define rdmsrl(msr,low) \
+	__asm__ __volatile__("rdmsr" : "=a"(low) : "c"(msr) : "edx")
+#define rdpmcl(ctr,low) \
+	__asm__ __volatile__("rdpmc" : "=a"(low) : "c"(ctr) : "edx")
+
+static void clear_msr_range(unsigned int base, unsigned int n)
+{
+	unsigned int i;
+
+	for(i = 0; i < n; ++i)
+		wrmsr(base+i, 0, 0);
+}
+
+static inline void set_in_cr4_local(unsigned int mask)
+{
+	write_cr4(read_cr4() | mask);
+}
+
+static inline void clear_in_cr4_local(unsigned int mask)
+{
+	write_cr4(read_cr4() & ~mask);
+}
+
+static unsigned int new_id(void)
+{
+	static spinlock_t lock = SPIN_LOCK_UNLOCKED;
+	static unsigned int counter;
+	int id;
+
+	spin_lock(&lock);
+	id = ++counter;
+	spin_unlock(&lock);
+	return id;
+}
+
+/****************************************************************
+ *								*
+ * Interrupt support via the local APIC.			*
+ *								*
+ ****************************************************************/
+
+#ifdef CONFIG_X86_LOCAL_APIC
+static void perfctr_default_ihandler(unsigned long pc)
+{
+}
+
+static perfctr_ihandler_t perfctr_ihandler = perfctr_default_ihandler;
+
+void do_perfctr_interrupt(struct pt_regs *regs)
+{
+	/* XXX: 2.5.28+: irq_enter() or preempt_disable() here */
+	/* XXX: recursive interrupts? delay the ACK, mask LVTPC, or queue? */
+	ack_APIC_irq();
+	(*perfctr_ihandler)(regs->eip);
+	/* XXX: 2.5.28+: irq_exit() or preempt_enable() here */
+}
+
+void perfctr_cpu_set_ihandler(perfctr_ihandler_t ihandler)
+{
+	perfctr_ihandler = ihandler ? ihandler : perfctr_default_ihandler;
+}
+
+static inline int perfctr_has_ictrs(const struct perfctr_cpu_state *state)
+{
+	return perfctr_cstatus_has_ictrs(state->cstatus);
+}
+
+static inline void perfctr_set_lvtpc(unsigned int vector)
+{
+	if( cpu_has_apic )
+		apic_write(APIC_LVTPC, vector);
+}
+
+#else	/* CONFIG_X86_LOCAL_APIC */
+static inline int perfctr_has_ictrs(const struct perfctr_cpu_state *state)
+{
+	return 0;
+}
+static inline void perfctr_set_lvtpc(unsigned int vector) { }
+#endif	/* CONFIG_X86_LOCAL_APIC */
+
+#ifdef CONFIG_SMP	/* which implies CONFIG_X86_LOCAL_APIC */
+static inline void set_isuspend_cpu(struct perfctr_cpu_state *state,
+				    const struct per_cpu_cache *cpu)
+{
+	state->k2.isuspend_cpu = cpu;
+}
+
+static inline int is_isuspend_cpu(const struct perfctr_cpu_state *state,
+				  const struct per_cpu_cache *cpu)
+{
+	return state->k2.isuspend_cpu == cpu;
+}
+
+static inline void clear_isuspend_cpu(struct perfctr_cpu_state *state)
+{
+	state->k2.isuspend_cpu = NULL;
+}
+#else	/* CONFIG_SMP */
+static inline void set_isuspend_cpu(struct perfctr_cpu_state *state,
+				    const struct per_cpu_cache *cpu) { }
+static inline int is_isuspend_cpu(const struct perfctr_cpu_state *state,
+				  const struct per_cpu_cache *cpu) { return 1; }
+static inline void clear_isuspend_cpu(struct perfctr_cpu_state *state) { }
+#endif	/* CONFIG_SMP */
+
+/****************************************************************
+ *								*
+ * Driver procedures.						*
+ *								*
+ ****************************************************************/
+
+/*
+ * Intel P5 family (Pentium, family code 5).
+ * - One TSC and two 40-bit PMCs.
+ * - A single 32-bit CESR (MSR 0x11) controls both PMCs.
+ *   CESR has two halves, each controlling one PMC.
+ *   To keep the API reasonably clean, the user puts 16 bits of
+ *   control data in each counter's evntsel; the driver combines
+ *   these to a single 32-bit CESR value.
+ * - Overflow interrupts are not available.
+ * - Pentium MMX added the RDPMC instruction. RDPMC has lower
+ *   overhead than RDMSR and it can be used in user-mode code.
+ * - The MMX events are not symmetric: some events are only available
+ *   for some PMC, and some event codes denote different events
+ *   depending on which PMCs they control.
+ */
+
+/* shared with MII and C6 */
+static int p5_like_check_control(struct perfctr_cpu_state *state,
+				 unsigned int reserved_bits, int is_c6)
+{
+	unsigned short cesr_half[2];
+	unsigned int pmc, evntsel, i;
+
+	if( state->control.nrictrs != 0 || state->control.nractrs > 2 )
+		return -EINVAL;
+	cesr_half[0] = 0;
+	cesr_half[1] = 0;
+	for(i = 0; i < state->control.nractrs; ++i) {
+		pmc = state->control.pmc_map[i];
+		if( pmc > 1 || cesr_half[pmc] != 0 )
+			return -EINVAL;
+		evntsel = state->control.evntsel[i];
+		/* protect reserved bits */
+		if( (evntsel & reserved_bits) != 0 )
+			return -EPERM;
+		/* the CPL field (if defined) must be non-zero */
+		if( !is_c6 && !(evntsel & P5_CESR_CPL) )
+			return -EINVAL;
+		cesr_half[pmc] = evntsel;
+	}
+	state->k1.p5_cesr = (cesr_half[1] << 16) | cesr_half[0];
+	return 0;
+}
+
+static int p5_check_control(struct perfctr_cpu_state *state)
+{
+	return p5_like_check_control(state, P5_CESR_RESERVED, 0);
+}
+
+/* shared with MII but not C6 */
+static void p5_write_control(const struct perfctr_cpu_state *state)
+{
+	struct per_cpu_cache *cpu;
+	unsigned int cesr;
+
+	cesr = state->k1.p5_cesr;
+	if( !cesr )	/* no PMC is on (this test doesn't work on C6) */
+		return;
+	cpu = &per_cpu_cache[smp_processor_id()];
+	if( cpu->k1.p5_cesr != cesr ) {
+		cpu->k1.p5_cesr = cesr;
+		wrmsr(MSR_P5_CESR, cesr, 0);
+	}
+}
+
+static void p5_read_counters(const struct perfctr_cpu_state *state,
+			     struct perfctr_low_ctrs *ctrs)
+{
+	unsigned int cstatus, nrctrs, i;
+
+	/* The P5 doesn't allocate a cache line on a write miss, so do
+	   a dummy read to avoid a write miss here _and_ a read miss
+	   later in our caller. */
+	asm("" : : "r"(ctrs->tsc));
+
+	cstatus = state->cstatus;
+	if( perfctr_cstatus_has_tsc(cstatus) )
+		rdtscl(ctrs->tsc);
+	nrctrs = perfctr_cstatus_nractrs(cstatus);
+	for(i = 0; i < nrctrs; ++i) {
+		unsigned int pmc = state->control.pmc_map[i];
+		rdmsrl(MSR_P5_CTR0+pmc, ctrs->pmc[i]);
+	}
+}
+
+/* used by P5MMX, MII, C6, VC3, P6, K7, P4 */
+static void rdpmc_read_counters(const struct perfctr_cpu_state *state,
+				struct perfctr_low_ctrs *ctrs)
+{
+	unsigned int cstatus, nrctrs, i;
+
+	cstatus = state->cstatus;
+	if( perfctr_cstatus_has_tsc(cstatus) )
+		rdtscl(ctrs->tsc);
+	nrctrs = perfctr_cstatus_nractrs(cstatus);
+	for(i = 0; i < nrctrs; ++i) {
+		unsigned int pmc = state->control.pmc_map[i];
+		rdpmcl(pmc, ctrs->pmc[i]);
+	}
+}
+
+/* shared with MII and C6 */
+static void p5_clear_counters(void)
+{
+	clear_msr_range(MSR_P5_CESR, 1+2);
+}
+
+/*
+ * Cyrix 6x86/MII/III.
+ * - Same MSR assignments as P5 MMX. Has RDPMC and two 48-bit PMCs.
+ * - Event codes and CESR formatting as in the plain P5 subset.
+ * - Many but not all P5 MMX event codes are implemented.
+ * - Cyrix adds a few more event codes. The event code is widened
+ *   to 7 bits, and Cyrix puts the high bit in CESR bit 10
+ *   (and CESR bit 26 for PMC1).
+ */
+
+static int mii_check_control(struct perfctr_cpu_state *state)
+{
+	return p5_like_check_control(state, MII_CESR_RESERVED, 0);
+}
+
+/*
+ * Centaur WinChip C6/2/3.
+ * - Same MSR assignments as P5 MMX. Has RDPMC and two 40-bit PMCs.
+ * - CESR is formatted with two halves, like P5. However, there
+ *   are no defined control fields for e.g. CPL selection, and
+ *   there is no defined method for stopping the counters.
+ * - Only a few event codes are defined.
+ * - The 64-bit TSC is synthesised from the low 32 bits of the
+ *   two PMCs, and CESR has to be set up appropriately.
+ *   Reprogramming CESR causes RDTSC to yield invalid results.
+ *   (The C6 may also hang in this case, due to C6 erratum I-13.)
+ *   Therefore, using the PMCs on any of these processors requires
+ *   that the TSC is not accessed at all:
+ *   1. The kernel must be configured or a TSC-less processor, i.e.
+ *      generic 586 or less.
+ *   2. The "notsc" boot parameter must be passed to the kernel.
+ *   3. User-space libraries and code must also be configured and
+ *      compiled for a generic 586 or less.
+ */
+
+#if !defined(CONFIG_X86_TSC)
+static int c6_check_control(struct perfctr_cpu_state *state)
+{
+	if( state->control.tsc_on )
+		return -EINVAL;
+	return p5_like_check_control(state, C6_CESR_RESERVED, 1);
+}
+
+static void c6_write_control(const struct perfctr_cpu_state *state)
+{
+	struct per_cpu_cache *cpu;
+	unsigned int cesr;
+
+	if( perfctr_cstatus_nractrs(state->cstatus) == 0 ) /* no PMC is on */
+		return;
+	cpu = &per_cpu_cache[smp_processor_id()];
+	cesr = state->k1.p5_cesr;
+	if( cpu->k1.p5_cesr != cesr ) {
+		cpu->k1.p5_cesr = cesr;
+		wrmsr(MSR_P5_CESR, cesr, 0);
+	}
+}
+#endif
+
+/*
+ * Intel P6 family (Pentium Pro, Pentium II, and Pentium III cores,
+ * and Xeon and Celeron versions of Pentium II and III cores).
+ * - One TSC and two 40-bit PMCs.
+ * - One 32-bit EVNTSEL MSR for each PMC.
+ * - EVNTSEL0 contains a global enable/disable bit.
+ *   That bit is reserved in EVNTSEL1.
+ * - Each EVNTSEL contains a CPL field.
+ * - Overflow interrupts are possible, but requires that the
+ *   local APIC is available. Some Mobile P6s have no local APIC.
+ * - The PMCs cannot be initialised with arbitrary values, since
+ *   wrmsr fills the high bits by sign-extending from bit 31.
+ * - Most events are symmetric, but a few are not.
+ */
+
+/* shared with K7 */
+static int p6_like_check_control(struct perfctr_cpu_state *state, int is_k7)
+{
+	unsigned int evntsel, i, nractrs, nrctrs, pmc_mask, pmc;
+
+	nractrs = state->control.nractrs;
+	nrctrs = nractrs + state->control.nrictrs;
+	if( nrctrs < nractrs || nrctrs > (is_k7 ? 4 : 2) )
+		return -EINVAL;
+
+	pmc_mask = 0;
+	for(i = 0; i < nrctrs; ++i) {
+		pmc = state->control.pmc_map[i];
+		if( pmc >= (is_k7 ? 4 : 2) || (pmc_mask & (1<<pmc)) )
+			return -EINVAL;
+		pmc_mask |= (1<<pmc);
+		evntsel = state->control.evntsel[i];
+		/* protect reserved bits */
+		if( evntsel & P6_EVNTSEL_RESERVED )
+			return -EPERM;
+		/* check ENable bit */
+		if( is_k7 ) {
+			/* ENable bit must be set in each evntsel */
+			if( !(evntsel & P6_EVNTSEL_ENABLE) )
+				return -EINVAL;
+		} else {
+			/* only evntsel[0] has the ENable bit */
+			if( evntsel & P6_EVNTSEL_ENABLE ) {
+				if( pmc > 0 )
+					return -EPERM;
+			} else {
+				if( pmc == 0 )
+					return -EINVAL;
+			}
+		}
+		/* the CPL field must be non-zero */
+		if( !(evntsel & P6_EVNTSEL_CPL) )
+			return -EINVAL;
+		/* INT bit must be off for a-mode and on for i-mode counters */
+		if( evntsel & P6_EVNTSEL_INT ) {
+			if( i < nractrs )
+				return -EINVAL;
+		} else {
+			if( i >= nractrs )
+				return -EINVAL;
+		}
+	}
+	state->k1.id = new_id();
+	return 0;
+}
+
+static int p6_check_control(struct perfctr_cpu_state *state)
+{
+	return p6_like_check_control(state, 0);
+}
+
+#ifdef CONFIG_X86_LOCAL_APIC
+/* PRE: perfctr_cstatus_has_ictrs(state->cstatus) != 0 */
+/* shared with K7 */
+static void p6_like_isuspend(struct perfctr_cpu_state *state,
+			     unsigned int msr_evntsel0)
+{
+	struct per_cpu_cache *cpu;
+	unsigned int cstatus, nrctrs, i;
+
+	cpu = &per_cpu_cache[smp_processor_id()];
+	cstatus = state->cstatus;
+	nrctrs = perfctr_cstatus_nrctrs(cstatus);
+	for(i = perfctr_cstatus_nractrs(cstatus); i < nrctrs; ++i) {
+		unsigned int pmc, now;
+		pmc = state->control.pmc_map[i];
+		cpu->control.evntsel[pmc] = 0;
+		wrmsr(msr_evntsel0+pmc, 0, 0);
+		rdpmcl(pmc, now);
+		state->sum.pmc[i] += now - state->start.pmc[i];
+		state->start.pmc[i] = now;
+	}
+	/* cpu->k1.id is still == state->k1.id */
+	set_isuspend_cpu(state, cpu);
+}
+
+/* PRE: perfctr_cstatus_has_ictrs(state->cstatus) != 0 */
+/* shared with K7 */
+static void p6_like_iresume(const struct perfctr_cpu_state *state,
+			    unsigned int msr_perfctr0)
+{
+	struct per_cpu_cache *cpu;
+	unsigned int cstatus, nrctrs, i;
+
+	cpu = &per_cpu_cache[smp_processor_id()];
+	if( cpu->k1.id == state->k1.id ) {
+		cpu->k1.id = 0; /* force reload of cleared EVNTSELs */
+		if( is_isuspend_cpu(state, cpu) )
+			return; /* skip reload of PERFCTRs */
+	}
+	cstatus = state->cstatus;
+	nrctrs = perfctr_cstatus_nrctrs(cstatus);
+	for(i = perfctr_cstatus_nractrs(cstatus); i < nrctrs; ++i) {
+		unsigned int pmc = state->control.pmc_map[i];
+		/* the -1 is correct for K7 but ignored by P6 */
+		wrmsr(msr_perfctr0+pmc, state->start.pmc[i], -1);
+	}
+	/* cpu->k1.id remains != state->k1.id */
+}
+
+static void p6_isuspend(struct perfctr_cpu_state *state)
+{
+	p6_like_isuspend(state, MSR_P6_EVNTSEL0);
+}
+
+static void p6_iresume(const struct perfctr_cpu_state *state)
+{
+	p6_like_iresume(state, MSR_P6_PERFCTR0);
+}
+#endif	/* CONFIG_X86_LOCAL_APIC */
+
+/* shared with K7 and VC3 */
+static void p6_like_write_control(const struct perfctr_cpu_state *state,
+				  unsigned int msr_evntsel0)
+{
+	struct per_cpu_cache *cpu;
+	unsigned int nrctrs, i;
+
+	cpu = &per_cpu_cache[smp_processor_id()];
+	if( cpu->k1.id == state->k1.id ) {
+		return;
+	}
+	nrctrs = perfctr_cstatus_nrctrs(state->cstatus);
+	for(i = 0; i < nrctrs; ++i) {
+		unsigned int evntsel = state->control.evntsel[i];
+		unsigned int pmc = state->control.pmc_map[i];
+		if( evntsel != cpu->control.evntsel[pmc] ) {
+			cpu->control.evntsel[pmc] = evntsel;
+			wrmsr(msr_evntsel0+pmc, evntsel, 0);
+		}
+	}
+	cpu->k1.id = state->k1.id;
+}
+
+/* shared with VC3 */
+static void p6_write_control(const struct perfctr_cpu_state *state)
+{
+	p6_like_write_control(state, MSR_P6_EVNTSEL0);
+}
+
+static void p6_clear_counters(void)
+{
+	clear_msr_range(MSR_P6_EVNTSEL0, 2);
+	clear_msr_range(MSR_P6_PERFCTR0, 2);
+}
+
+/*
+ * AMD K7 family (Athlon, Duron).
+ * - Somewhat similar to the Intel P6 family.
+ * - Four 48-bit PMCs.
+ * - Four 32-bit EVNTSEL MSRs with similar layout as in P6.
+ * - Completely different MSR assignments :-(
+ * - Fewer countable events defined :-(
+ * - The events appear to be completely symmetric.
+ * - The EVNTSEL MSRs are symmetric since each has its own enable bit.
+ * - Publicly available documentation is incomplete.
+ */
+
+static int k7_check_control(struct perfctr_cpu_state *state)
+{
+	return p6_like_check_control(state, 1);
+}
+
+#ifdef CONFIG_X86_LOCAL_APIC
+static void k7_isuspend(struct perfctr_cpu_state *state)
+{
+	p6_like_isuspend(state, MSR_K7_EVNTSEL0);
+}
+
+static void k7_iresume(const struct perfctr_cpu_state *state)
+{
+	p6_like_iresume(state, MSR_K7_PERFCTR0);
+}
+#endif	/* CONFIG_X86_LOCAL_APIC */
+
+static void k7_write_control(const struct perfctr_cpu_state *state)
+{
+	p6_like_write_control(state, MSR_K7_EVNTSEL0);
+}
+
+static void k7_clear_counters(void)
+{
+	clear_msr_range(MSR_K7_EVNTSEL0, 4+4);
+}
+
+/*
+ * VIA C3 family.
+ * - A Centaur design somewhat similar to the P6/Celeron.
+ * - PERFCTR0 is an alias for the TSC, and EVNTSEL0 is read-only.
+ * - PERFCTR1 is 32 bits wide.
+ * - EVNTSEL1 has no defined control fields, and there is no
+ *   defined method for stopping the counter.
+ * - According to testing, the reserved fields in EVNTSEL1 have
+ *   no function. We always fill them with zeroes.
+ * - Only a few event codes are defined.
+ * - No local APIC or interrupt-mode support.
+ * - pmc_map[0] must be 1, if nractrs == 1.
+ */
+static int vc3_check_control(struct perfctr_cpu_state *state)
+{
+	if( state->control.nrictrs || state->control.nractrs > 1 )
+		return -EINVAL;
+	if( state->control.nractrs == 1 ) {
+		if( state->control.pmc_map[0] != 1 )
+			return -EINVAL;
+		if( state->control.evntsel[0] & VC3_EVNTSEL1_RESERVED )
+			return -EPERM;
+		state->k1.id = state->control.evntsel[0];
+	} else
+		state->k1.id = 0;
+	return 0;
+}
+
+static void vc3_clear_counters(void)
+{
+	/* Not documented, but seems to be default after boot. */
+	wrmsr(MSR_P6_EVNTSEL0+1, 0x00070079, 0);
+}
+
+/*
+ * Intel Pentium 4.
+ * Current implementation restrictions:
+ * - No DS/PEBS support.
+ */
+
+/*
+ * Table 15-4 in the IA32 Volume 3 manual contains a 18x8 entry mapping
+ * from counter/CCCR number (0-17) and ESCR SELECT value (0-7) to the
+ * actual ESCR MSR number. This mapping contains some repeated patterns,
+ * so we can compact it to a 4x8 table of MSR offsets:
+ *
+ * 1. CCCRs 16 and 17 are mapped just like CCCRs 13 and 14, respectively.
+ *    Thus, we only consider the 16 CCCRs 0-15.
+ * 2. The CCCRs are organised in pairs, and both CCCRs in a pair use the
+ *    same mapping. Thus, we only consider the 8 pairs 0-7.
+ * 3. In each pair of pairs, the second odd-numbered pair has the same domain
+ *    as the first even-numbered pair, and the range is 1+ the range of the
+ *    the first even-numbered pair. For example, CCCR(0) and (1) map ESCR
+ *    SELECT(7) to 0x3A0, and CCCR(2) and (3) map it to 0x3A1.
+ *    The only exception is that pair (7) [CCCRs 14 and 15] does not have
+ *    ESCR SELECT(3) in its domain, like pair (6) [CCCRs 12 and 13] has.
+ *    NOTE: Revisions of IA32 Volume 3 older than #245472-007 had an error
+ *    in this table: CCCRs 12, 13, and 16 had their mappings for ESCR SELECT
+ *    values 2 and 3 swapped.
+ * 4. All MSR numbers are on the form 0x3??. Instead of storing these as
+ *    16-bit numbers, the table only stores the 8-bit offsets from 0x300.
+ */
+
+static const unsigned char p4_cccr_escr_map[4][8] = {
+	/* 0x00 and 0x01 as is, 0x02 and 0x03 are +1 */
+	[0x00/4] {	[7] 0xA0,
+			[6] 0xA2,
+			[2] 0xAA,
+			[4] 0xAC,
+			[0] 0xB2,
+			[1] 0xB4,
+			[3] 0xB6,
+			[5] 0xC8, },
+	/* 0x04 and 0x05 as is, 0x06 and 0x07 are +1 */
+	[0x04/4] {	[0] 0xC0,
+			[2] 0xC2,
+			[1] 0xC4, },
+	/* 0x08 and 0x09 as is, 0x0A and 0x0B are +1 */
+	[0x08/4] {	[1] 0xA4,
+			[0] 0xA6,
+			[5] 0xA8,
+			[2] 0xAE,
+			[3] 0xB0, },
+	/* 0x0C, 0x0D, and 0x10 as is,
+	   0x0E, 0x0F, and 0x11 are +1 except [3] is not in the domain */
+	[0x0C/4] {	[4] 0xB8,
+			[5] 0xCC,
+			[6] 0xE0,
+			[0] 0xBA,
+			[2] 0xBC,
+			[3] 0xBE,
+			[1] 0xCA, },
+};
+
+static unsigned int p4_escr_addr(unsigned int pmc, unsigned int cccr_val)
+{
+	unsigned int escr_select, pair, escr_offset;
+
+	escr_select = P4_CCCR_ESCR_SELECT(cccr_val);
+	if( pmc > 0x11 )
+		return 0;	/* pmc range error */
+	if( pmc > 0x0F )
+		pmc -= 3;	/* 0 <= pmc <= 0x0F */
+	pair = pmc / 2;		/* 0 <= pair <= 7 */
+	escr_offset = p4_cccr_escr_map[pair / 2][escr_select];
+	if( !escr_offset || (pair == 7 && escr_select == 3) )
+		return 0;	/* ESCR SELECT range error */
+	return escr_offset + (pair & 1) + 0x300;
+};
+
+static int p4_check_control(struct perfctr_cpu_state *state)
+{
+	unsigned int i, nractrs, nrctrs, pmc_mask;
+
+	nractrs = state->control.nractrs;
+	nrctrs = nractrs + state->control.nrictrs;
+	if( nrctrs < nractrs || nrctrs > 18 )
+		return -EINVAL;
+
+	pmc_mask = 0;
+	for(i = 0; i < nrctrs; ++i) {
+		unsigned int pmc, cccr_val, escr_val, escr_addr;
+		/* check that pmc_map[] is well-defined;
+		   pmc_map[i] is what we pass to RDPMC, the PMC itself
+		   is extracted by masking off the FAST_RDPMC flag */
+		pmc = state->control.pmc_map[i] & ~P4_FAST_RDPMC;
+		if( pmc >= 18 || (pmc_mask & (1<<pmc)) )
+			return -EINVAL;
+		pmc_mask |= (1<<pmc);
+		/* check CCCR contents */
+		cccr_val = state->control.evntsel[i];
+		if( cccr_val & P4_CCCR_RESERVED )
+			return -EPERM;
+		if( (cccr_val & P4_CCCR_REQUIRED) != P4_CCCR_REQUIRED )
+			return -EINVAL;
+		if( !(cccr_val & (P4_CCCR_ENABLE | P4_CCCR_CASCADE)) )
+			return -EINVAL;
+		if( cccr_val & P4_CCCR_OVF_PMI_T0 ) {
+			if( i < nractrs )
+				return -EINVAL;
+		} else {
+			if( i >= nractrs )
+				return -EINVAL;
+		}
+		/* check ESCR contents */
+		escr_val = state->control.evntsel_aux[i];
+		if( escr_val & P4_ESCR_RESERVED )
+			return -EPERM;
+		if( !(escr_val & P4_ESCR_CPL_T0) )
+			return -EINVAL;
+		/* compute and cache ESCR address */
+		escr_addr = p4_escr_addr(pmc, cccr_val);
+		if( !escr_addr )
+			return -EINVAL;		/* ESCR SELECT range error */
+		/* XXX: Two counters could map to the same ESCR. Should we
+		   check that they use the same ESCR value? */
+		state->k2.p4_escr_map[i] = escr_addr - MSR_P4_ESCR0;
+	}
+	/* check ReplayTagging control (PEBS_ENABLE and PEBS_MATRIX_VERT) */
+	if( state->control.p4.pebs_enable ) {
+		if( !nrctrs )
+			return -EPERM;
+		if( state->control.p4.pebs_enable & P4_PE_RESERVED )
+			return -EPERM;
+		if( !(state->control.p4.pebs_enable & P4_PE_UOP_TAG ) )
+			return -EINVAL;
+		if( !(state->control.p4.pebs_enable & P4_PE_REPLAY_TAG_BITS) )
+			return -EINVAL;
+		if( state->control.p4.pebs_matrix_vert & P4_PMV_RESERVED )
+			return -EPERM;
+		if( !(state->control.p4.pebs_matrix_vert & P4_PMV_REPLAY_TAG_BITS) )
+			return -EINVAL;
+	} else if( state->control.p4.pebs_matrix_vert )
+		return -EPERM;
+	state->k1.id = new_id();
+	return 0;
+}
+
+#ifdef CONFIG_X86_LOCAL_APIC
+/* PRE: perfctr_cstatus_has_ictrs(state->cstatus) != 0 */
+/* XXX: merge with p6_like_isuspend() later */
+static void p4_isuspend(struct perfctr_cpu_state *state)
+{
+	struct per_cpu_cache *cpu;
+	unsigned int cstatus, nrctrs, i;
+
+	cpu = &per_cpu_cache[smp_processor_id()];
+	cstatus = state->cstatus;
+	nrctrs = perfctr_cstatus_nrctrs(cstatus);
+	for(i = perfctr_cstatus_nractrs(cstatus); i < nrctrs; ++i) {
+		unsigned int pmc_raw, pmc_idx, now;
+		pmc_raw = state->control.pmc_map[i];
+		pmc_idx = pmc_raw & P4_MASK_FAST_RDPMC;
+		cpu->control.evntsel[pmc_idx] = 0;
+		wrmsr(MSR_P4_CCCR0+pmc_idx, 0, 0); /* P4 quirk: also clear OVF */
+		rdpmcl(pmc_raw, now);
+		state->sum.pmc[i] += now - state->start.pmc[i];
+		state->start.pmc[i] = now;
+	}
+	/* cpu->k1.id is still == state->k1.id */
+	set_isuspend_cpu(state, cpu);
+	/* another P4 quirk: must unmask LVTPC */
+	apic_write(APIC_LVTPC, LOCAL_PERFCTR_VECTOR);
+}
+
+/* PRE: perfctr_cstatus_has_ictrs(state->cstatus) != 0 */
+/* XXX: merge with p6_like_iresume() later */
+static void p4_iresume(const struct perfctr_cpu_state *state)
+{
+	struct per_cpu_cache *cpu;
+	unsigned int cstatus, nrctrs, i;
+
+	cpu = &per_cpu_cache[smp_processor_id()];
+	if( cpu->k1.id == state->k1.id ) {
+		cpu->k1.id = 0; /* force reload of cleared EVNTSELs */
+		if( is_isuspend_cpu(state, cpu) )
+			return; /* skip reload of PERFCTRs */
+	}
+	cstatus = state->cstatus;
+	nrctrs = perfctr_cstatus_nrctrs(cstatus);
+	for(i = perfctr_cstatus_nractrs(cstatus); i < nrctrs; ++i) {
+		unsigned int pmc = state->control.pmc_map[i] & P4_MASK_FAST_RDPMC;
+		wrmsr(MSR_P4_PERFCTR0+pmc, state->start.pmc[i], -1);
+	}
+	/* cpu->k1.id remains != state->k1.id */
+}
+#endif	/* CONFIG_X86_LOCAL_APIC */
+
+static void p4_write_control(const struct perfctr_cpu_state *state)
+{
+	struct per_cpu_cache *cpu;
+	unsigned int nrctrs, i;
+
+	cpu = &per_cpu_cache[smp_processor_id()];
+	if( cpu->k1.id == state->k1.id ) {
+		return;
+	}
+	nrctrs = perfctr_cstatus_nrctrs(state->cstatus);
+	for(i = 0; i < nrctrs; ++i) {
+		unsigned int escr_val, escr_off, cccr_val, pmc;
+		escr_val = state->control.evntsel_aux[i];
+		escr_off = state->k2.p4_escr_map[i];
+		if( escr_val != cpu->control.escr[escr_off] ) {
+			cpu->control.escr[escr_off] = escr_val;
+			wrmsr(MSR_P4_ESCR0+escr_off, escr_val, 0);
+		}
+		cccr_val = state->control.evntsel[i];
+		pmc = state->control.pmc_map[i] & P4_MASK_FAST_RDPMC;
+		if( cccr_val != cpu->control.evntsel[pmc] ) {
+			cpu->control.evntsel[pmc] = cccr_val;
+			wrmsr(MSR_P4_CCCR0+pmc, cccr_val, 0);
+		}
+	}
+	if( state->control.p4.pebs_enable != cpu->control.pebs_enable ) {
+		cpu->control.pebs_enable = state->control.p4.pebs_enable;
+		wrmsr(MSR_P4_PEBS_ENABLE, cpu->control.pebs_enable, 0);
+	}
+	if( state->control.p4.pebs_matrix_vert != cpu->control.pebs_matrix_vert ) {
+		cpu->control.pebs_matrix_vert = state->control.p4.pebs_matrix_vert;
+		wrmsr(MSR_P4_PEBS_MATRIX_VERT, cpu->control.pebs_matrix_vert, 0);
+	}
+	cpu->k1.id = state->k1.id;
+}
+
+static void p4_clear_counters(void)
+{
+	/* MSR 0x3F0 seems to have a default value of 0xFC00, but current
+	   docs doesn't fully define it, so leave it alone for now. */
+	/* clear PEBS_ENABLE and PEBS_MATRIX_VERT; they handle both PEBS
+	   and ReplayTagging, and should exist even if PEBS is disabled */
+	clear_msr_range(0x3F1, 2);
+	clear_msr_range(0x3A0, 31);
+	clear_msr_range(0x3C0, 6);
+	clear_msr_range(0x3C8, 6);
+	clear_msr_range(0x3E0, 2);
+	clear_msr_range(MSR_P4_CCCR0, 18);
+	clear_msr_range(MSR_P4_PERFCTR0, 18);
+}
+
+/*
+ * Generic driver for any x86 with a working TSC.
+ */
+
+static int generic_check_control(struct perfctr_cpu_state *state)
+{
+	if( state->control.nractrs || state->control.nrictrs )
+		return -EINVAL;
+	return 0;
+}
+
+static void generic_write_control(const struct perfctr_cpu_state *state)
+{
+}
+
+static void generic_read_counters(const struct perfctr_cpu_state *state,
+				  struct perfctr_low_ctrs *ctrs)
+{
+	rdtscl(ctrs->tsc);
+}
+
+static void generic_clear_counters(void)
+{
+}
+
+/*
+ * Driver methods, internal and exported.
+ *
+ * Frequently called functions (write_control, read_counters,
+ * isuspend and iresume) are back-patched to invoke the correct
+ * processor-specific methods directly, thereby saving the
+ * overheads of indirect function calls.
+ *
+ * Backpatchable call sites must have been "finalised" after
+ * initialisation. The reason for this is that unsynchronised code
+ * modification doesn't work in multiprocessor systems, due to
+ * Intel P6 errata. Consequently, all backpatchable call sites
+ * must be known and local to this file.
+ */
+
+static int redirect_call_disable;
+
+static void redirect_call(void *ra, void *to)
+{
+	/* XXX: make this function __init later */
+	if( redirect_call_disable )
+		printk(KERN_ERR __FILE__ ":%s: unresolved call to %p at %p\n",
+		       __FUNCTION__, to, ra);
+	/* we can only redirect `call near relative' instructions */
+	if( *((unsigned char*)ra - 5) != 0xE8 ) {
+		printk(KERN_WARNING __FILE__ ":%s: unable to redirect caller %p to %p\n",
+		       __FUNCTION__, ra, to);
+		return;
+	}
+	*(int*)((char*)ra - 4) = (char*)to - (char*)ra;
+}
+
+static void (*write_control)(const struct perfctr_cpu_state*);
+static void perfctr_cpu_write_control(const struct perfctr_cpu_state *state)
+{
+	redirect_call(__builtin_return_address(0), write_control);
+	return write_control(state);
+}
+
+static void (*read_counters)(const struct perfctr_cpu_state*,
+			     struct perfctr_low_ctrs*);
+static void perfctr_cpu_read_counters(const struct perfctr_cpu_state *state,
+				      struct perfctr_low_ctrs *ctrs)
+{
+	redirect_call(__builtin_return_address(0), read_counters);
+	return read_counters(state, ctrs);
+}
+
+#ifdef CONFIG_X86_LOCAL_APIC
+static void (*cpu_isuspend)(struct perfctr_cpu_state*);
+static void perfctr_cpu_isuspend(struct perfctr_cpu_state *state)
+{
+	redirect_call(__builtin_return_address(0), cpu_isuspend);
+	return cpu_isuspend(state);
+}
+
+static void (*cpu_iresume)(const struct perfctr_cpu_state*);
+static void perfctr_cpu_iresume(const struct perfctr_cpu_state *state)
+{
+	redirect_call(__builtin_return_address(0), cpu_iresume);
+	return cpu_iresume(state);
+}
+
+/* Call perfctr_cpu_ireload() just before perfctr_cpu_resume() to
+   bypass internal caching and force a reload if the I-mode PMCs. */
+void perfctr_cpu_ireload(struct perfctr_cpu_state *state)
+{
+#if !defined(CONFIG_SMP)
+	/* This works because we know the process owning 'state'
+	 * will be resumed on the current CPU.
+	 */
+	per_cpu_cache[smp_processor_id()].k1.id = 0;
+#else
+	/* This works because of the additional is_isuspend_cpu() check
+	 * that iresume() performs on SMP. The UP version above fails
+	 * when iresume() is issued via remote control on SMP, since we
+	 * don't know on which CPU the process owning 'state' will be
+	 * resumed. Inferior alternatives are:
+	 * 1. Allocate a new control id to 'state', but that is ugly.
+	 * 2. Invalidate cpu->k1.id on every CPU, but this would penalise
+	 *    other processes, require a locking protocol for cpu->k1.id
+	 *    accesses, or require an expensive smp_call_function() call
+	 *    to perform the update atomically on all CPUs.
+	 */
+	clear_isuspend_cpu(state);
+#endif
+}
+
+/* PRE: the counters have been suspended and sampled by perfctr_cpu_suspend() */
+unsigned int perfctr_cpu_identify_overflow(struct perfctr_cpu_state *state)
+{
+	unsigned int cstatus, nrctrs, pmc, pmc_mask;
+
+	cstatus = state->cstatus;
+	pmc = perfctr_cstatus_nractrs(cstatus);
+	nrctrs = perfctr_cstatus_nrctrs(cstatus);
+
+	for(pmc_mask = 0; pmc < nrctrs; ++pmc) {
+		if( (int)state->start.pmc[pmc] >= 0 ) { /* XXX: ">" ? */
+			/* XXX: "+=" to correct for overshots */
+			state->start.pmc[pmc] = state->control.ireset[pmc];
+			pmc_mask |= (1 << pmc);
+			/* On a P4 we should now clear the OVF flag in the
+			   counter's CCCR. However, p4_isuspend() already
+			   did that as a side-effect of clearing the CCCR
+			   in order to stop the i-mode counters. */
+		}
+	}
+	return pmc_mask;
+}
+#else	/* CONFIG_X86_LOCAL_APIC */
+static inline void perfctr_cpu_isuspend(struct perfctr_cpu_state *state) { }
+static inline void perfctr_cpu_iresume(const struct perfctr_cpu_state *state) { }
+#endif	/* CONFIG_X86_LOCAL_APIC */
+
+static inline int check_ireset(const struct perfctr_cpu_state *state)
+{
+#ifdef CONFIG_X86_LOCAL_APIC
+	unsigned int nrctrs, i;
+
+	i = state->control.nractrs;
+	nrctrs = i + state->control.nrictrs;
+	for(; i < nrctrs; ++i)
+		if( state->control.ireset[i] >= 0 )
+			return -EINVAL;
+#endif
+	return 0;
+}
+
+static inline void setup_imode_start_values(struct perfctr_cpu_state *state)
+{
+#ifdef CONFIG_X86_LOCAL_APIC
+	unsigned int cstatus, nrctrs, i;
+
+	cstatus = state->cstatus;
+	nrctrs = perfctr_cstatus_nrctrs(cstatus);
+	for(i = perfctr_cstatus_nractrs(cstatus); i < nrctrs; ++i)
+		state->start.pmc[i] = state->control.ireset[i];
+#endif
+}
+
+static int (*check_control)(struct perfctr_cpu_state*);
+int perfctr_cpu_update_control(struct perfctr_cpu_state *state)
+{
+	int err;
+
+	clear_isuspend_cpu(state);
+	state->cstatus = 0;
+
+	/* disallow i-mode counters if we cannot catch the interrupts */
+	if( !(perfctr_info.cpu_features & PERFCTR_FEATURE_PCINT)
+	    && state->control.nrictrs )
+		return -EPERM;
+
+	err = check_control(state);
+	if( err < 0 )
+		return err;
+	err = check_ireset(state);
+	if( err < 0 )
+		return err;
+	state->cstatus = perfctr_mk_cstatus(state->control.tsc_on,
+					    state->control.nractrs,
+					    state->control.nrictrs);
+	setup_imode_start_values(state);
+	return 0;
+}
+
+void perfctr_cpu_suspend(struct perfctr_cpu_state *state)
+{
+	unsigned int i, cstatus, nractrs;
+	struct perfctr_low_ctrs now;
+
+	if( perfctr_has_ictrs(state) )
+		perfctr_cpu_isuspend(state);
+	perfctr_cpu_read_counters(state, &now);
+	cstatus = state->cstatus;
+	if( perfctr_cstatus_has_tsc(cstatus) )
+		state->sum.tsc += now.tsc - state->start.tsc;
+	nractrs = perfctr_cstatus_nractrs(cstatus);
+	for(i = 0; i < nractrs; ++i)
+		state->sum.pmc[i] += now.pmc[i] - state->start.pmc[i];
+}
+
+void perfctr_cpu_resume(struct perfctr_cpu_state *state)
+{
+	if( perfctr_has_ictrs(state) )
+		perfctr_cpu_iresume(state);
+	perfctr_cpu_write_control(state);
+	perfctr_cpu_read_counters(state, &state->start);
+	/* XXX: if (SMP && start.tsc == now.tsc) ++now.tsc; */
+}
+
+void perfctr_cpu_sample(struct perfctr_cpu_state *state)
+{
+	unsigned int i, cstatus, nractrs;
+	struct perfctr_low_ctrs now;
+
+	perfctr_cpu_read_counters(state, &now);
+	cstatus = state->cstatus;
+	if( perfctr_cstatus_has_tsc(cstatus) ) {
+		state->sum.tsc += now.tsc - state->start.tsc;
+		state->start.tsc = now.tsc;
+	}
+	nractrs = perfctr_cstatus_nractrs(cstatus);
+	for(i = 0; i < nractrs; ++i) {
+		state->sum.pmc[i] += now.pmc[i] - state->start.pmc[i];
+		state->start.pmc[i] = now.pmc[i];
+	}
+}
+
+static void (*clear_counters)(void);
+static void perfctr_cpu_clear_counters(void)
+{
+	return clear_counters();
+}
+
+/****************************************************************
+ *								*
+ * Processor detection and initialisation procedures.		*
+ *								*
+ ****************************************************************/
+
+/* see comment above at redirect_call() */
+static void __init finalise_backpatching(void)
+{
+	struct per_cpu_cache *cpu;
+	struct perfctr_cpu_state state;
+
+	cpu = &per_cpu_cache[smp_processor_id()];
+	memset(cpu, 0, sizeof *cpu);
+	memset(&state, 0, sizeof state);
+	state.cstatus =
+		(perfctr_info.cpu_features & PERFCTR_FEATURE_PCINT)
+		? perfctr_mk_cstatus(0, 0, 1)
+		: 0;
+	perfctr_cpu_sample(&state);
+	perfctr_cpu_resume(&state);
+	perfctr_cpu_suspend(&state);
+
+	redirect_call_disable = 1;
+}
+
+static int __init intel_init(void)
+{
+	unsigned int misc_enable;
+
+	if( !cpu_has_tsc )
+		return -ENODEV;
+	switch( current_cpu_data.x86 ) {
+	case 5:
+		if( cpu_has_mmx ) {
+			perfctr_info.cpu_type = PERFCTR_X86_INTEL_P5MMX;
+			read_counters = rdpmc_read_counters;
+
+			/* Avoid Pentium Erratum 74. */
+			if( current_cpu_data.x86_model == 4 &&
+			    (current_cpu_data.x86_mask == 4 ||
+			     (current_cpu_data.x86_mask == 3 &&
+			      ((cpuid_eax(1) >> 12) & 0x3) == 1)) )
+				perfctr_info.cpu_features &= ~PERFCTR_FEATURE_RDPMC;
+		} else {
+			perfctr_info.cpu_type = PERFCTR_X86_INTEL_P5;
+			perfctr_info.cpu_features &= ~PERFCTR_FEATURE_RDPMC;
+			read_counters = p5_read_counters;
+		}
+		write_control = p5_write_control;
+		check_control = p5_check_control;
+		clear_counters = p5_clear_counters;
+		return 0;
+	case 6:
+		if( current_cpu_data.x86_model >= 7 )	/* PIII */
+			perfctr_info.cpu_type = PERFCTR_X86_INTEL_PIII;
+		else if( current_cpu_data.x86_model >= 3 )	/* PII or Celeron */
+			perfctr_info.cpu_type = PERFCTR_X86_INTEL_PII;
+		else {
+			perfctr_info.cpu_type = PERFCTR_X86_INTEL_P6;
+
+			/* Avoid Pentium Pro Erratum 26. */
+			if( current_cpu_data.x86_mask < 9 )
+				perfctr_info.cpu_features &= ~PERFCTR_FEATURE_RDPMC;
+		}
+		read_counters = rdpmc_read_counters;
+		write_control = p6_write_control;
+		check_control = p6_check_control;
+		clear_counters = p6_clear_counters;
+#ifdef CONFIG_X86_LOCAL_APIC
+		if( cpu_has_apic ) {
+			perfctr_info.cpu_features |= PERFCTR_FEATURE_PCINT;
+			cpu_isuspend = p6_isuspend;
+			cpu_iresume = p6_iresume;
+		}
+#endif
+		return 0;
+	case 15:	/* Pentium 4 */
+		rdmsrl(MSR_P4_MISC_ENABLE, misc_enable);
+		if( !(misc_enable & MSR_P4_MISC_ENABLE_PERF_AVAIL) )
+			break;
+		if( current_cpu_data.x86_model >= 2 )
+			/* Model 2 changed the ESCR Event Mask programming
+			   details for several events. */
+			perfctr_info.cpu_type = PERFCTR_X86_INTEL_P4M2;
+		else
+			perfctr_info.cpu_type = PERFCTR_X86_INTEL_P4;
+		read_counters = rdpmc_read_counters;
+		write_control = p4_write_control;
+		check_control = p4_check_control;
+		clear_counters = p4_clear_counters;
+#ifdef CONFIG_X86_LOCAL_APIC
+		if( cpu_has_apic ) {
+			perfctr_info.cpu_features |= PERFCTR_FEATURE_PCINT;
+			cpu_isuspend = p4_isuspend;
+			cpu_iresume = p4_iresume;
+		}
+#endif
+		return 0;
+	}
+	return -ENODEV;
+}
+
+static int __init amd_init(void)
+{
+	if( !cpu_has_tsc )
+		return -ENODEV;
+	switch( current_cpu_data.x86 ) {
+	case 6:	/* K7. Model 1 does not have a local APIC.
+		   AMD Document #22007 Revision J hints that APIC-less
+		   K7s signal overflows as debug interrupts. */
+		perfctr_info.cpu_type = PERFCTR_X86_AMD_K7;
+		read_counters = rdpmc_read_counters;
+		write_control = k7_write_control;
+		check_control = k7_check_control;
+		clear_counters = k7_clear_counters;
+#ifdef CONFIG_X86_LOCAL_APIC
+		if( cpu_has_apic ) {
+			perfctr_info.cpu_features |= PERFCTR_FEATURE_PCINT;
+			cpu_isuspend = k7_isuspend;
+			cpu_iresume = k7_iresume;
+		}
+#endif
+		return 0;
+	}
+	return -ENODEV;
+}
+
+static int __init cyrix_init(void)
+{
+	if( !cpu_has_tsc )
+		return -ENODEV;
+	switch( current_cpu_data.x86 ) {
+	case 6:	/* 6x86MX, MII, or III */
+		perfctr_info.cpu_type = PERFCTR_X86_CYRIX_MII;
+		read_counters = rdpmc_read_counters;
+		write_control = p5_write_control;
+		check_control = mii_check_control;
+		clear_counters = p5_clear_counters;
+		return 0;
+	}
+	return -ENODEV;
+}
+
+static int __init centaur_init(void)
+{
+	switch( current_cpu_data.x86 ) {
+#if !defined(CONFIG_X86_TSC)
+	case 5:
+		switch( current_cpu_data.x86_model ) {
+		case 4: /* WinChip C6 */
+			perfctr_info.cpu_type = PERFCTR_X86_WINCHIP_C6;
+			break;
+		case 8: /* WinChip 2, 2A, or 2B */
+		case 9: /* WinChip 3, a 2A with larger cache and lower voltage */
+			perfctr_info.cpu_type = PERFCTR_X86_WINCHIP_2;
+			break;
+		default:
+			return -ENODEV;
+		}
+		/*
+		 * TSC must be inaccessible for perfctrs to work.
+		 */
+		if( !(read_cr4() & X86_CR4_TSD) || cpu_has_tsc )
+			return -ENODEV;
+		perfctr_info.cpu_features &= ~PERFCTR_FEATURE_RDTSC;
+		read_counters = rdpmc_read_counters;
+		write_control = c6_write_control;
+		check_control = c6_check_control;
+		clear_counters = p5_clear_counters;
+		return 0;
+#endif
+	case 6: /* VIA C3 */
+		if( !cpu_has_tsc )
+			return -ENODEV;
+		switch( current_cpu_data.x86_model ) {
+		case 6:	/* VIA C3 (Cyrix III) */
+		case 7:	/* VIA C3 Samuel 2 or Ezra */
+		case 8:	/* VIA C3 Ezra-T */
+			break;
+		default:
+			return -ENODEV;
+		}
+		perfctr_info.cpu_type = PERFCTR_X86_VIA_C3;
+		read_counters = rdpmc_read_counters;
+		write_control = p6_write_control;
+		check_control = vc3_check_control;
+		clear_counters = vc3_clear_counters;
+		return 0;
+	}
+	return -ENODEV;
+}
+
+static int __init generic_init(void)
+{
+	if( !cpu_has_tsc )
+		return -ENODEV;
+	perfctr_info.cpu_features &= ~PERFCTR_FEATURE_RDPMC;
+	perfctr_info.cpu_type = PERFCTR_X86_GENERIC;
+	check_control = generic_check_control;
+	write_control = generic_write_control;
+	read_counters = generic_read_counters;
+	clear_counters = generic_clear_counters;
+	return 0;
+}
+
+static char generic_name[] __initdata = "Generic x86 with TSC";
+static char p5_name[] __initdata = "Intel Pentium";
+static char p5mmx_name[] __initdata = "Intel Pentium MMX";
+static char p6_name[] __initdata = "Intel Pentium Pro";
+static char pii_name[] __initdata = "Intel Pentium II";
+static char piii_name[] __initdata = "Intel Pentium III";
+static char mii_name[] __initdata = "Cyrix 6x86MX/MII/III";
+static char wcc6_name[] __initdata = "WinChip C6";
+static char wc2_name[] __initdata = "WinChip 2/3";
+static char k7_name[] __initdata = "AMD K7";
+static char vc3_name[] __initdata = "VIA C3";
+static char p4_name[] __initdata = "Intel Pentium 4";
+static char p4m2_name[] __initdata = "Intel Pentium 4 Model 2";
+
+char *perfctr_cpu_name[] __initdata = {
+	[PERFCTR_X86_GENERIC] generic_name,
+	[PERFCTR_X86_INTEL_P5] p5_name,
+	[PERFCTR_X86_INTEL_P5MMX] p5mmx_name,
+	[PERFCTR_X86_INTEL_P6] p6_name,
+	[PERFCTR_X86_INTEL_PII] pii_name,
+	[PERFCTR_X86_INTEL_PIII] piii_name,
+	[PERFCTR_X86_CYRIX_MII] mii_name,
+	[PERFCTR_X86_WINCHIP_C6] wcc6_name,
+	[PERFCTR_X86_WINCHIP_2] wc2_name,
+	[PERFCTR_X86_AMD_K7] k7_name,
+	[PERFCTR_X86_VIA_C3] vc3_name,
+	[PERFCTR_X86_INTEL_P4] p4_name,
+	[PERFCTR_X86_INTEL_P4M2] p4m2_name,
+};
+
+static void __init perfctr_cpu_init_one(void *ignore)
+{
+	perfctr_cpu_clear_counters();
+	perfctr_set_lvtpc(LOCAL_PERFCTR_VECTOR);
+	if( perfctr_info.cpu_features & PERFCTR_FEATURE_RDPMC )
+		set_in_cr4_local(X86_CR4_PCE);
+}
+
+static void __exit perfctr_cpu_exit_one(void *ignore)
+{
+	perfctr_cpu_clear_counters();
+	perfctr_set_lvtpc(APIC_DM_NMI | APIC_LVT_MASKED);
+	if( perfctr_info.cpu_features & PERFCTR_FEATURE_RDPMC )
+		clear_in_cr4_local(X86_CR4_PCE);
+}
+
+static void invalidate_per_cpu_cache(void)
+{
+	/*
+	 * per_cpu_cache[] is initialised to contain "impossible"
+	 * evntsel values guaranteed to differ from anything accepted
+	 * by perfctr_cpu_update_control(). This way, initialisation of
+	 * a CPU's evntsel MSRs will happen automatically the first time
+	 * perfctr_cpu_write_control() executes on it.
+	 * All-bits-one works for all currently supported processors.
+	 * The memset also sets the ids to -1, which is intentional.
+	 */
+	memset(per_cpu_cache, ~0, sizeof per_cpu_cache);
+}
+
+/****************************************************************
+ *								*
+ * NMI watchdog interface.					*
+ *								*
+ ****************************************************************/
+
+#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_PM)
+
+static void __init unregister_nmi_pmdev(void)
+{
+	if( nmi_pmdev ) {
+		apic_pm_unregister(nmi_pmdev);
+		nmi_pmdev = 0;
+	}
+}
+
+static int x86_pm_callback(struct pm_dev *dev, pm_request_t rqst, void *data)
+{
+	/* XXX: incomplete */
+	return 0;
+}
+
+static struct pm_dev *x86_pmdev;
+
+static void __init x86_pm_init(void)
+{
+	x86_pmdev = apic_pm_register(PM_SYS_DEV, 0, x86_pm_callback);
+}
+
+static void __exit x86_pm_exit(void)
+{
+	if( x86_pmdev ) {
+		apic_pm_unregister(x86_pmdev);
+		x86_pmdev = NULL;
+	}
+}
+
+#else	/* CONFIG_X86_LOCAL_APIC && CONFIG_PM */
+static inline void unregister_nmi_pmdev(void) { }
+static inline void x86_pm_init(void) { }
+static inline void x86_pm_exit(void) { }
+#endif	/* CONFIG_X86_LOCAL_APIC && CONFIG_PM */
+
+#ifdef CONFIG_X86_LOCAL_APIC
+static void __init disable_nmi_watchdog(void)
+{
+	if( nmi_perfctr_msr ) {
+		nmi_perfctr_msr = 0;
+		printk(KERN_NOTICE "perfctr: disabled nmi_watchdog\n");
+		unregister_nmi_pmdev();
+	}
+}
+#else
+static inline void disable_nmi_watchdog(void) { }
+#endif
+
+/****************************************************************
+ *								*
+ * Top-level initialisation.					*
+ *								*
+ ****************************************************************/
+
+int __init perfctr_cpu_init(void)
+{
+	int err = -ENODEV;
+
+	/* RDPMC and RDTSC are on by default. They will be disabled
+	   by the init procedures if necessary. */
+	perfctr_info.cpu_features = PERFCTR_FEATURE_RDPMC | PERFCTR_FEATURE_RDTSC;
+
+	if( cpu_has_msr ) {
+		switch( current_cpu_data.x86_vendor ) {
+		case X86_VENDOR_INTEL:
+			err = intel_init();
+			break;
+		case X86_VENDOR_AMD:
+			err = amd_init();
+			break;
+		case X86_VENDOR_CYRIX:
+			err = cyrix_init();
+			break;
+		case X86_VENDOR_CENTAUR:
+			err = centaur_init();
+		}
+	}
+	if( err ) {
+		err = generic_init();	/* last resort */
+		if( err )
+			return err;
+	}
+	/*
+	 * Put the hardware in a sane state:
+	 * - finalise resolution of backpatchable call sites
+	 * - clear perfctr MSRs
+	 * - set up APIC_LVTPC
+	 * - set CR4.PCE [on permanently due to __flush_tlb_global()]
+	 * - install our default interrupt handler
+	 */
+	if( perfctr_info.cpu_features & PERFCTR_FEATURE_RDPMC )
+		mmu_cr4_features |= X86_CR4_PCE;
+	finalise_backpatching();
+	perfctr_cpu_init_one(NULL);
+	smp_call_function(perfctr_cpu_init_one, NULL, 1, 1);
+	perfctr_cpu_set_ihandler(NULL);
+	/*
+	 * Fix up the connection to the local APIC:
+	 * - disable and disconnect the NMI watchdog
+	 * - register our PM callback
+	 */
+	disable_nmi_watchdog();
+	x86_pm_init();
+
+	invalidate_per_cpu_cache();
+
+	perfctr_info.cpu_khz = cpu_khz;
+	/* XXX: TDB */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,5,23)
+/* export the cpu_online_map instead? */
+#define smp_num_cpus	num_online_cpus()
+#endif
+	perfctr_info.nrcpus = smp_num_cpus;
+
+	return 0;
+}
+
+void __exit perfctr_cpu_exit(void)
+{
+	if( perfctr_info.cpu_features & PERFCTR_FEATURE_RDPMC )
+		mmu_cr4_features &= ~X86_CR4_PCE;
+	perfctr_cpu_exit_one(NULL);
+	smp_call_function(perfctr_cpu_exit_one, NULL, 1, 1);
+	perfctr_cpu_set_ihandler(NULL);
+	x86_pm_exit();
+	/* XXX: restart nmi watchdog? */
+}
+
+/****************************************************************
+ *								*
+ * Hardware reservation for higher-level drivers.		*
+ *								*
+ ****************************************************************/
+
+/* XXX: hmm, need a spinlock here I think */
+static const char *current_service = 0;
+
+const char *perfctr_cpu_reserve(const char *service)
+{
+	if( current_service )
+		return current_service;
+	current_service = service;
+	return 0;
+}
+
+static void perfctr_cpu_clear_one(void *ignore)
+{
+	perfctr_cpu_clear_counters();
+}
+
+void perfctr_cpu_release(const char *service)
+{
+	if( service != current_service ) {
+		printk(KERN_ERR "%s: attempt by %s to release while reserved by %s\n",
+		       __FUNCTION__, service, current_service);
+	} else {
+		/* power down the counters */
+		invalidate_per_cpu_cache();
+		perfctr_cpu_clear_one(NULL);
+		smp_call_function(perfctr_cpu_clear_one, NULL, 1, 1);
+
+		perfctr_cpu_set_ihandler(NULL);
+		current_service = 0;
+	}
+}
diff -ruN linux-2.5.44/drivers/perfctr/x86_compat.c linux-2.5.44.perfctr-3.0-pre2/drivers/perfctr/x86_compat.c
--- linux-2.5.44/drivers/perfctr/x86_compat.c	Thu Jan  1 01:00:00 1970
+++ linux-2.5.44.perfctr-3.0-pre2/drivers/perfctr/x86_compat.c	Fri Oct 11 10:47:05 2002
@@ -0,0 +1,38 @@
+/* $Id: x86_compat.c,v 1.1 2002/10/11 08:47:05 mikpe Exp $
+ * Performance-monitoring counters driver.
+ * x86 perfctrs backwards compatibility support code.
+ *
+ * Copyright (C) 1999-2002  Mikael Pettersson
+ */
+#include <linux/config.h>
+#include <linux/version.h>
+//#include <linux/init.h>
+//#include <linux/kernel.h>
+#include <linux/sched.h>
+//#include <asm/processor.h>
+#include <asm/perfctr.h>
+//#include <asm/fixmap.h>	/* for 2.4 */
+//#include <asm/apic.h>
+struct hw_interrupt_type;
+#include <asm/hw_irq.h>	/* for 2.4 */
+
+#if PERFCTR_INTERRUPT_SUPPORT && (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,8))
+#define BUILD_PERFCTR_INTERRUPT(x,v) XBUILD_PERFCTR_INTERRUPT(x,v)
+#define XBUILD_PERFCTR_INTERRUPT(x,v) \
+asmlinkage void x(void); \
+__asm__( \
+	"\n.text\n\t" \
+	__ALIGN_STR "\n\t" \
+	".type " SYMBOL_NAME_STR(x) ",@function\n" \
+	".globl " SYMBOL_NAME_STR(x) "\n" \
+SYMBOL_NAME_STR(x) ":\n\t" \
+	"pushl $" #v "-256\n\t" \
+	SAVE_ALL \
+	"pushl %esp\n\t" \
+	"call " SYMBOL_NAME_STR(do_ ## x) "\n\t" \
+	"addl $4,%esp\n\t" \
+	"jmp ret_from_intr\n\t" \
+	".size " SYMBOL_NAME_STR(x) ",.-" SYMBOL_NAME_STR(x) "\n" \
+	".previous\n");
+BUILD_PERFCTR_INTERRUPT(perfctr_interrupt,LOCAL_PERFCTR_VECTOR)
+#endif
diff -ruN linux-2.5.44/drivers/perfctr/x86_compat.h linux-2.5.44.perfctr-3.0-pre2/drivers/perfctr/x86_compat.h
--- linux-2.5.44/drivers/perfctr/x86_compat.h	Thu Jan  1 01:00:00 1970
+++ linux-2.5.44.perfctr-3.0-pre2/drivers/perfctr/x86_compat.h	Wed Oct 23 21:38:11 2002
@@ -0,0 +1,38 @@
+/* $Id: x86_compat.h,v 1.21 2002/10/06 22:47:05 mikpe Exp $
+ * Performance-monitoring counters driver.
+ * x86-specific compatibility definitions for 2.4/2.5 kernels.
+ *
+ * Copyright (C) 2000-2002  Mikael Pettersson
+ */
+#include <linux/config.h>
+#include <linux/version.h>
+
+/* 2.4.9-ac3 added {read,write}_cr4() macros in <asm-i386/system.h> */
+#if !defined(write_cr4)
+static inline void write_cr4(unsigned int x)
+{
+	__asm__ __volatile__("movl %0,%%cr4" : : "r"(x));
+}
+
+static inline unsigned int read_cr4(void)
+{
+	unsigned int x;
+	__asm__ __volatile__("movl %%cr4,%0" : "=r"(x));
+	return x;
+}
+#endif
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,5,18)
+
+/* missing from <asm-i386/cpufeature.h> */
+#define cpu_has_msr	boot_cpu_has(X86_FEATURE_MSR)
+
+#else /* for 2.4 only, not 2.2 */
+
+/* missing from <asm-i386/processor.h> */
+#define cpu_has_mmx	(test_bit(X86_FEATURE_MMX,  boot_cpu_data.x86_capability))
+#define cpu_has_msr	(test_bit(X86_FEATURE_MSR,  boot_cpu_data.x86_capability))
+
+#endif
+
+extern unsigned long cpu_khz;
diff -ruN linux-2.5.44/include/asm-i386/perfctr.h linux-2.5.44.perfctr-3.0-pre2/include/asm-i386/perfctr.h
--- linux-2.5.44/include/asm-i386/perfctr.h	Thu Jan  1 01:00:00 1970
+++ linux-2.5.44.perfctr-3.0-pre2/include/asm-i386/perfctr.h	Wed Oct 23 21:34:59 2002
@@ -0,0 +1,157 @@
+/* $Id: perfctr.h,v 1.26 2002/10/20 21:50:02 mikpe Exp $
+ * x86 Performance-Monitoring Counters driver
+ *
+ * Copyright (C) 1999-2002  Mikael Pettersson
+ */
+#ifndef _ASM_I386_PERFCTR_H
+#define _ASM_I386_PERFCTR_H
+
+struct perfctr_sum_ctrs {
+	unsigned long long tsc;
+	unsigned long long pmc[18];
+};
+
+struct perfctr_low_ctrs {
+	unsigned int tsc;
+	unsigned int pmc[18];
+};
+
+struct perfctr_cpu_control {
+	unsigned int tsc_on;
+	unsigned int nractrs;		/* # of a-mode counters */
+	unsigned int nrictrs;		/* # of i-mode counters */
+	unsigned int pmc_map[18];
+	unsigned int evntsel[18];	/* one per counter, even on P5 */
+	unsigned int evntsel_aux[18];	/* e.g. P4 ESCR contents */
+	struct {
+		unsigned int pebs_enable;	/* for replay tagging */
+		unsigned int pebs_matrix_vert;	/* for replay tagging */
+	} p4;
+	int ireset[18];			/* <= 0, for i-mode counters */
+};
+
+struct perfctr_cpu_state {
+	unsigned int cstatus;
+	union {
+		unsigned int p5_cesr;
+		unsigned int id;	/* cache owner id */
+	} k1;
+	struct perfctr_sum_ctrs sum;
+	struct perfctr_low_ctrs start;
+	struct perfctr_cpu_control control;
+	struct {
+		unsigned int p4_escr_map[18];
+		const void *isuspend_cpu;
+	} k2;
+};
+
+/* `struct perfctr_cpu_state' binary layout version number */
+#define PERFCTR_CPU_STATE_MAGIC	0x0201	/* 2.1 */
+
+/* cstatus is a re-encoding of control.tsc_on/nractrs/nrictrs
+   which should have less overhead in most cases */
+
+static inline
+unsigned int perfctr_mk_cstatus(unsigned int tsc_on, unsigned int nractrs,
+				unsigned int nrictrs)
+{
+	return (tsc_on<<31) | (nrictrs<<16) | ((nractrs+nrictrs)<<8) | nractrs;
+}
+
+static inline unsigned int perfctr_cstatus_enabled(unsigned int cstatus)
+{
+	return cstatus;
+}
+
+static inline int perfctr_cstatus_has_tsc(unsigned int cstatus)
+{
+	return (int)cstatus < 0;	/* test and jump on sign */
+}
+
+static inline unsigned int perfctr_cstatus_nractrs(unsigned int cstatus)
+{
+	return cstatus & 0x7F;		/* and with imm8 */
+}
+
+static inline unsigned int perfctr_cstatus_nrctrs(unsigned int cstatus)
+{
+	return (cstatus >> 8) & 0x7F;
+}
+
+static inline unsigned int perfctr_cstatus_has_ictrs(unsigned int cstatus)
+{
+	return cstatus & (0x7F << 16);
+}
+
+/*
+ * 'struct siginfo' support for perfctr overflow signals.
+ * In unbuffered mode, si_code is set to SI_PMC_OVF and a bitmask
+ * describing which perfctrs overflowed is put in si_pmc_ovf_mask.
+ * A bitmask is used since more than one perfctr can have overflowed
+ * by the time the interrupt handler runs.
+ *
+ * glibc's <signal.h> doesn't seem to define __SI_FAULT or __SI_CODE(),
+ * and including <asm/siginfo.h> as well may cause redefinition errors,
+ * so the user and kernel values are different #defines here.
+ */
+#ifdef __KERNEL__
+#define SI_PMC_OVF	(__SI_FAULT|'P')
+#else
+#define SI_PMC_OVF	('P')
+#endif
+#define si_pmc_ovf_mask	_sifields._pad[0] /* XXX: use an unsigned field later */
+
+#ifdef __KERNEL__
+
+#ifdef CONFIG_PERFCTR
+
+/* Driver init/exit. */
+extern int perfctr_cpu_init(void);
+extern void perfctr_cpu_exit(void);
+
+/* CPU type name. */
+extern char *perfctr_cpu_name[];
+
+/* Hardware reservation. */
+extern const char *perfctr_cpu_reserve(const char *service);
+extern void perfctr_cpu_release(const char *service);
+
+/* PRE: state has no running interrupt-mode counters.
+   Check that the new control data is valid.
+   Update the driver's private control data.
+   Returns a negative error code if the control data is invalid. */
+extern int perfctr_cpu_update_control(struct perfctr_cpu_state *state);
+
+/* Read a-mode counters. Subtract from start and accumulate into sums. */
+extern void perfctr_cpu_suspend(struct perfctr_cpu_state *state);
+
+/* Write control registers. Read a-mode counters into start. */
+extern void perfctr_cpu_resume(struct perfctr_cpu_state *state);
+
+/* Perform an efficient combined suspend/resume operation. */
+extern void perfctr_cpu_sample(struct perfctr_cpu_state *state);
+
+typedef void (*perfctr_ihandler_t)(unsigned long pc);
+
+#ifdef CONFIG_X86_LOCAL_APIC
+#define PERFCTR_INTERRUPT_SUPPORT 1	/* for higher-level drivers */
+extern void perfctr_cpu_set_ihandler(perfctr_ihandler_t);
+extern void perfctr_cpu_ireload(struct perfctr_cpu_state*);
+extern unsigned int perfctr_cpu_identify_overflow(struct perfctr_cpu_state*);
+#else
+static inline void perfctr_cpu_set_ihandler(perfctr_ihandler_t x) { }
+#endif
+
+#endif	/* CONFIG_PERFCTR */
+
+#if defined(CONFIG_PERFCTR) && defined(CONFIG_X86_LOCAL_APIC)
+extern void perfctr_interrupt(void);
+#define perfctr_vector_init() \
+	set_intr_gate(LOCAL_PERFCTR_VECTOR, perfctr_interrupt)
+#else
+#define perfctr_vector_init() do{}while(0)
+#endif
+
+#endif	/* __KERNEL__ */
+
+#endif	/* _ASM_I386_PERFCTR_H */

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