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Subject[patch] Performance Counters for Linux, v2

[ Performance counters are special hardware registers available on most
modern CPUs. These register count the number of certain types of hw
events: such as instructions executed, cachemisses suffered, or
branches mis-predicted, without slowing down the kernel or
applications. These registers can also trigger interrupts when a
threshold number of events have passed - and can thus be used to
profile the code that runs on that CPU. ]

This is version 2 of our Performance Counters subsystem implementation.

The biggest user-visible change in this release is a new user-space
text-mode profiling utility that is based on this code: KernelTop.

KernelTop can be downloaded from:

http://redhat.com/~mingo/perfcounters/kerneltop.c

It's a standalone .c file that needs no extra libraries - it only needs a
CONFIG_PERF_COUNTERS=y kernel to run on.

This utility is intended for kernel developers - it's basically a dynamic
kernel profiler that gets hardware counter events dispatched to it
continuously, which it feeds into a histogram and outputs it
periodically.

Here is a screenshot of it:

------------------------------------------------------------------------------
KernelTop: 250880 irqs/sec [NMI, 10000 cycles], (all, cpu: 0)
------------------------------------------------------------------------------
events RIP kernel function
______ ________________ _______________
17319 - ffffffff8106f8fa : audit_syscall_exit
16300 - ffffffff81042ce2 : sys_rt_sigprocmask
11031 - ffffffff8106fdc8 : audit_syscall_entry
10880 - ffffffff8100bd8d : rff_trace
9780 - ffffffff810a232f : kfree [ehci_hcd]
9707 - ffffffff81298cb7 : _spin_lock_irq [ehci_hcd]
7903 - ffffffff8106db17 : unroll_tree_refs
7266 - ffffffff81138d10 : copy_user_generic_string
5751 - ffffffff8100be45 : sysret_check
4803 - ffffffff8100bea8 : sysret_signal
4696 - ffffffff8100bdb0 : system_call
4425 - ffffffff8100bdc0 : system_call_after_swapgs
2855 - ffffffff810ae183 : path_put [ext3]
2773 - ffffffff8100bedb : auditsys
1589 - ffffffff810b6864 : dput [sunrpc]
1253 - ffffffff8100be40 : ret_from_sys_call
690 - ffffffff8105034c : current_kernel_time [ext3]
673 - ffffffff81042bd4 : sys_sigprocmask
611 - ffffffff8100bf25 : sysret_audit
It will correctly profile core kernel, module space and vsyscall areas as
well. It allows the use of the most common hw counters: cycles,
instructions, branches, cachemisses, cache-references and branch-misses.

KernelTop does not have to be started/stopped - it will continously
profile the system and updates the histogram as the workload changes. The
histogram is not cumulative: old workload effects will time out
gradually. For example if the system goes idle, then the profiler output
will go down to near zero within 10-20 seconds. So there's no need to
stop or restart profiling - it all updates automatically, as the workflow
changes its characteristics.

KernelTop can also profile raw event IDs. For example, on a Core2 CPU, to
profile the "Number of instruction length decoder stalls" (raw event
0x0087) during a hackbench run, i did this:

$ ./kerneltop -e -$(printf "%d\n" 0x00000087) -c 10000 -n 1
------------------------------------------------------------------------------
KernelTop: 331 irqs/sec [NMI, 10000 raw:0087], (all, 2 CPUs)
------------------------------------------------------------------------------
events RIP kernel function
______ ________________ _______________
1016 - ffffffff802a611e : kmem_cache_alloc_node
898 - ffffffff804ca381 : sock_wfree
64 - ffffffff80567306 : schedule
50 - ffffffff804cdb39 : skb_release_head_state
45 - ffffffff8053ed54 : unix_write_space
33 - ffffffff802a6a4d : __kmalloc_node
18 - ffffffff802a642c : cache_alloc_refill
13 - ffffffff804cdd50 : __alloc_skb
7 - ffffffff8053ec0a : unix_shutdown
[ The printf is done to pass in a negative event number as a parameter. ]

We also made a good number of internal changes as well to the subsystem:

There's a new "counter group record" facility that is a straightforward
extension of the existing "irq record" notification type. This record
type can be set on a 'master' counter, and if the master counter triggers
an IRQ or an NMI, all the 'secondary' counters are read out atomically
and are put into the counter-group record. The result can then be read()
out by userspace via a single system call. (Based on extensive feedback
from Paul Mackerras and David Miller, thanks guys!)

The other big change is the support of virtual task counters via counter
scheduling: a task can specify more counters than there are on the CPU,
the kernel will then schedule the counters periodically to spread out hw
resources. So for example if a task starts 6 counters on a CPU that has
only two hardware counters, it still gets this output:

counter[0 cycles ]: 5204680573 , delta: 1733680843 events
counter[1 instructions ]: 1364468045 , delta: 454818351 events
counter[2 cache-refs ]: 12732 , delta: 4399 events
counter[3 cache-misses ]: 1009 , delta: 336 events
counter[4 branch-instructions ]: 125993304 , delta: 42006998 events
counter[5 branch-misses ]: 1946 , delta: 649 events

See this sample code at:

http://redhat.com/~mingo/perfcounters/hello-loop.c

There's also now the ability to do NMI profiling: this works both for per
CPU and per task counters. NMI counters are transparent and are enabled
via the PERF_COUNTER_NMI bit in the "hardware event type" parameter of
the sys_perf_counter_open() system call.

There's also more generic x86 support: all 4 generic PMCs of Nehalem /
Core i7 are supported - i've run 4 instances of KernelTop and they used
up four separate PMCs.

There's also perf counters debug output that can be triggered via sysrq,
for diagnostic purposes.

Ingo, Thomas

------------------->
The latest performance counters experimental git tree can be found at:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git perfcounters/core

--------------->
Ingo Molnar (2):
performance counters: documentation
performance counters: x86 support
Thomas Gleixner (1):
performance counters: core code


Documentation/perf-counters.txt | 104 +++
arch/x86/Kconfig | 1 +
arch/x86/ia32/ia32entry.S | 3 +-
arch/x86/include/asm/hardirq_32.h | 1 +
arch/x86/include/asm/hw_irq.h | 2 +
arch/x86/include/asm/intel_arch_perfmon.h | 34 +-
arch/x86/include/asm/irq_vectors.h | 5 +
arch/x86/include/asm/mach-default/entry_arch.h | 5 +
arch/x86/include/asm/pda.h | 1 +
arch/x86/include/asm/thread_info.h | 4 +-
arch/x86/include/asm/unistd_32.h | 1 +
arch/x86/include/asm/unistd_64.h | 3 +-
arch/x86/kernel/apic.c | 2 +
arch/x86/kernel/cpu/Makefile | 12 +-
arch/x86/kernel/cpu/common.c | 2 +
arch/x86/kernel/cpu/perf_counter.c | 571 ++++++++++++++
arch/x86/kernel/entry_64.S | 6 +
arch/x86/kernel/irq.c | 5 +
arch/x86/kernel/irqinit_32.c | 3 +
arch/x86/kernel/irqinit_64.c | 5 +
arch/x86/kernel/signal_32.c | 8 +-
arch/x86/kernel/signal_64.c | 5 +
arch/x86/kernel/syscall_table_32.S | 1 +
drivers/char/sysrq.c | 2 +
include/linux/perf_counter.h | 171 +++++
include/linux/sched.h | 9 +
include/linux/syscalls.h | 6 +
init/Kconfig | 29 +
kernel/Makefile | 1 +
kernel/fork.c | 1 +
kernel/perf_counter.c | 945 ++++++++++++++++++++++++
kernel/sched.c | 24 +
kernel/sys_ni.c | 3 +
33 files changed, 1954 insertions(+), 21 deletions(-)
create mode 100644 Documentation/perf-counters.txt
create mode 100644 arch/x86/kernel/cpu/perf_counter.c
create mode 100644 include/linux/perf_counter.h
create mode 100644 kernel/perf_counter.c
diff --git a/Documentation/perf-counters.txt b/Documentation/perf-counters.txt
new file mode 100644
index 0000000..19033a0
--- /dev/null
+++ b/Documentation/perf-counters.txt
@@ -0,0 +1,104 @@
+
+Performance Counters for Linux
+------------------------------
+
+Performance counters are special hardware registers available on most modern
+CPUs. These registers count the number of certain types of hw events: such
+as instructions executed, cachemisses suffered, or branches mis-predicted -
+without slowing down the kernel or applications. These registers can also
+trigger interrupts when a threshold number of events have passed - and can
+thus be used to profile the code that runs on that CPU.
+
+The Linux Performance Counter subsystem provides an abstraction of these
+hardware capabilities. It provides per task and per CPU counters, and
+it provides event capabilities on top of those.
+
+Performance counters are accessed via special file descriptors.
+There's one file descriptor per virtual counter used.
+
+The special file descriptor is opened via the perf_counter_open()
+system call:
+
+ int
+ perf_counter_open(u32 hw_event_type,
+ u32 hw_event_period,
+ u32 record_type,
+ pid_t pid,
+ int cpu);
+
+The syscall returns the new fd. The fd can be used via the normal
+VFS system calls: read() can be used to read the counter, fcntl()
+can be used to set the blocking mode, etc.
+
+Multiple counters can be kept open at a time, and the counters
+can be poll()ed.
+
+When creating a new counter fd, 'hw_event_type' is one of:
+
+ enum hw_event_types {
+ PERF_COUNT_CYCLES,
+ PERF_COUNT_INSTRUCTIONS,
+ PERF_COUNT_CACHE_REFERENCES,
+ PERF_COUNT_CACHE_MISSES,
+ PERF_COUNT_BRANCH_INSTRUCTIONS,
+ PERF_COUNT_BRANCH_MISSES,
+ };
+
+These are standardized types of events that work uniformly on all CPUs
+that implements Performance Counters support under Linux. If a CPU is
+not able to count branch-misses, then the system call will return
+-EINVAL.
+
+[ Note: more hw_event_types are supported as well, but they are CPU
+ specific and are enumerated via /sys on a per CPU basis. Raw hw event
+ types can be passed in as negative numbers. For example, to count
+ "External bus cycles while bus lock signal asserted" events on Intel
+ Core CPUs, pass in a -0x4064 event type value. ]
+
+The parameter 'hw_event_period' is the number of events before waking up
+a read() that is blocked on a counter fd. Zero value means a non-blocking
+counter.
+
+'record_type' is the type of data that a read() will provide for the
+counter, and it can be one of:
+
+ enum perf_record_type {
+ PERF_RECORD_SIMPLE,
+ PERF_RECORD_IRQ,
+ };
+
+a "simple" counter is one that counts hardware events and allows
+them to be read out into a u64 count value. (read() returns 8 on
+a successful read of a simple counter.)
+
+An "irq" counter is one that will also provide an IRQ context information:
+the IP of the interrupted context. In this case read() will return
+the 8-byte counter value, plus the Instruction Pointer address of the
+interrupted context.
+
+The 'pid' parameter allows the counter to be specific to a task:
+
+ pid == 0: if the pid parameter is zero, the counter is attached to the
+ current task.
+
+ pid > 0: the counter is attached to a specific task (if the current task
+ has sufficient privilege to do so)
+
+ pid < 0: all tasks are counted (per cpu counters)
+
+The 'cpu' parameter allows a counter to be made specific to a full
+CPU:
+
+ cpu >= 0: the counter is restricted to a specific CPU
+ cpu == -1: the counter counts on all CPUs
+
+Note: the combination of 'pid == -1' and 'cpu == -1' is not valid.
+
+A 'pid > 0' and 'cpu == -1' counter is a per task counter that counts
+events of that task and 'follows' that task to whatever CPU the task
+gets schedule to. Per task counters can be created by any user, for
+their own tasks.
+
+A 'pid == -1' and 'cpu == x' counter is a per CPU counter that counts
+all events on CPU-x. Per CPU counters need CAP_SYS_ADMIN privilege.
+
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ac22bb7..5a2d74a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -651,6 +651,7 @@ config X86_UP_IOAPIC
config X86_LOCAL_APIC
def_bool y
depends on X86_64 || (X86_32 && (X86_UP_APIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
+ select HAVE_PERF_COUNTERS

config X86_IO_APIC
def_bool y
diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index 256b00b..3c14ed0 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -823,7 +823,8 @@ ia32_sys_call_table:
.quad compat_sys_signalfd4
.quad sys_eventfd2
.quad sys_epoll_create1
- .quad sys_dup3 /* 330 */
+ .quad sys_dup3 /* 330 */
.quad sys_pipe2
.quad sys_inotify_init1
+ .quad sys_perf_counter_open
ia32_syscall_end:
diff --git a/arch/x86/include/asm/hardirq_32.h b/arch/x86/include/asm/hardirq_32.h
index 5ca135e..b3e475d 100644
--- a/arch/x86/include/asm/hardirq_32.h
+++ b/arch/x86/include/asm/hardirq_32.h
@@ -9,6 +9,7 @@ typedef struct {
unsigned long idle_timestamp;
unsigned int __nmi_count; /* arch dependent */
unsigned int apic_timer_irqs; /* arch dependent */
+ unsigned int apic_perf_irqs; /* arch dependent */
unsigned int irq0_irqs;
unsigned int irq_resched_count;
unsigned int irq_call_count;
diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
index b97aecb..c22900e 100644
--- a/arch/x86/include/asm/hw_irq.h
+++ b/arch/x86/include/asm/hw_irq.h
@@ -30,6 +30,8 @@
/* Interrupt handlers registered during init_IRQ */
extern void apic_timer_interrupt(void);
extern void error_interrupt(void);
+extern void perf_counter_interrupt(void);
+
extern void spurious_interrupt(void);
extern void thermal_interrupt(void);
extern void reschedule_interrupt(void);
diff --git a/arch/x86/include/asm/intel_arch_perfmon.h b/arch/x86/include/asm/intel_arch_perfmon.h
index fa0fd06..71598a9 100644
--- a/arch/x86/include/asm/intel_arch_perfmon.h
+++ b/arch/x86/include/asm/intel_arch_perfmon.h
@@ -1,22 +1,24 @@
#ifndef _ASM_X86_INTEL_ARCH_PERFMON_H
#define _ASM_X86_INTEL_ARCH_PERFMON_H

-#define MSR_ARCH_PERFMON_PERFCTR0 0xc1
-#define MSR_ARCH_PERFMON_PERFCTR1 0xc2
+#define MSR_ARCH_PERFMON_PERFCTR0 0xc1
+#define MSR_ARCH_PERFMON_PERFCTR1 0xc2

-#define MSR_ARCH_PERFMON_EVENTSEL0 0x186
-#define MSR_ARCH_PERFMON_EVENTSEL1 0x187
+#define MSR_ARCH_PERFMON_EVENTSEL0 0x186
+#define MSR_ARCH_PERFMON_EVENTSEL1 0x187

-#define ARCH_PERFMON_EVENTSEL0_ENABLE (1 << 22)
-#define ARCH_PERFMON_EVENTSEL_INT (1 << 20)
-#define ARCH_PERFMON_EVENTSEL_OS (1 << 17)
-#define ARCH_PERFMON_EVENTSEL_USR (1 << 16)
+#define ARCH_PERFMON_EVENTSEL0_ENABLE (1 << 22)
+#define ARCH_PERFMON_EVENTSEL_INT (1 << 20)
+#define ARCH_PERFMON_EVENTSEL_OS (1 << 17)
+#define ARCH_PERFMON_EVENTSEL_USR (1 << 16)

-#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_SEL (0x3c)
-#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_UMASK (0x00 << 8)
-#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX (0)
+#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_SEL 0x3c
+#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_UMASK (0x00 << 8)
+#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX 0
#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_PRESENT \
- (1 << (ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX))
+ (1 << (ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX))
+
+#define ARCH_PERFMON_BRANCH_MISSES_RETIRED 6

union cpuid10_eax {
struct {
@@ -28,4 +30,12 @@ union cpuid10_eax {
unsigned int full;
};

+#ifdef CONFIG_PERF_COUNTERS
+extern void init_hw_perf_counters(void);
+extern void perf_counters_lapic_init(int nmi);
+#else
+static inline void init_hw_perf_counters(void) { }
+static inline void perf_counters_lapic_init(int nmi) { }
+#endif
+
#endif /* _ASM_X86_INTEL_ARCH_PERFMON_H */
diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index 0005adb..b8d277f 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -87,6 +87,11 @@
#define LOCAL_TIMER_VECTOR 0xef

/*
+ * Performance monitoring interrupt vector:
+ */
+#define LOCAL_PERF_VECTOR 0xee
+
+/*
* First APIC vector available to drivers: (vectors 0x30-0xee) we
* start at 0x31(0x41) to spread out vectors evenly between priority
* levels. (0x80 is the syscall vector)
diff --git a/arch/x86/include/asm/mach-default/entry_arch.h b/arch/x86/include/asm/mach-default/entry_arch.h
index 6b1add8..ad31e5d 100644
--- a/arch/x86/include/asm/mach-default/entry_arch.h
+++ b/arch/x86/include/asm/mach-default/entry_arch.h
@@ -25,10 +25,15 @@ BUILD_INTERRUPT(irq_move_cleanup_interrupt,IRQ_MOVE_CLEANUP_VECTOR)
* a much simpler SMP time architecture:
*/
#ifdef CONFIG_X86_LOCAL_APIC
+
BUILD_INTERRUPT(apic_timer_interrupt,LOCAL_TIMER_VECTOR)
BUILD_INTERRUPT(error_interrupt,ERROR_APIC_VECTOR)
BUILD_INTERRUPT(spurious_interrupt,SPURIOUS_APIC_VECTOR)

+#ifdef CONFIG_PERF_COUNTERS
+BUILD_INTERRUPT(perf_counter_interrupt, LOCAL_PERF_VECTOR)
+#endif
+
#ifdef CONFIG_X86_MCE_P4THERMAL
BUILD_INTERRUPT(thermal_interrupt,THERMAL_APIC_VECTOR)
#endif
diff --git a/arch/x86/include/asm/pda.h b/arch/x86/include/asm/pda.h
index 2fbfff8..90a8d9d 100644
--- a/arch/x86/include/asm/pda.h
+++ b/arch/x86/include/asm/pda.h
@@ -30,6 +30,7 @@ struct x8664_pda {
short isidle;
struct mm_struct *active_mm;
unsigned apic_timer_irqs;
+ unsigned apic_perf_irqs;
unsigned irq0_irqs;
unsigned irq_resched_count;
unsigned irq_call_count;
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index e44d379..810bf26 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -80,6 +80,7 @@ struct thread_info {
#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
#define TIF_SECCOMP 8 /* secure computing */
#define TIF_MCE_NOTIFY 10 /* notify userspace of an MCE */
+#define TIF_PERF_COUNTERS 11 /* notify perf counter work */
#define TIF_NOTSC 16 /* TSC is not accessible in userland */
#define TIF_IA32 17 /* 32bit process */
#define TIF_FORK 18 /* ret_from_fork */
@@ -103,6 +104,7 @@ struct thread_info {
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP (1 << TIF_SECCOMP)
#define _TIF_MCE_NOTIFY (1 << TIF_MCE_NOTIFY)
+#define _TIF_PERF_COUNTERS (1 << TIF_PERF_COUNTERS)
#define _TIF_NOTSC (1 << TIF_NOTSC)
#define _TIF_IA32 (1 << TIF_IA32)
#define _TIF_FORK (1 << TIF_FORK)
@@ -135,7 +137,7 @@ struct thread_info {

/* Only used for 64 bit */
#define _TIF_DO_NOTIFY_MASK \
- (_TIF_SIGPENDING|_TIF_MCE_NOTIFY|_TIF_NOTIFY_RESUME)
+ (_TIF_SIGPENDING|_TIF_MCE_NOTIFY|_TIF_PERF_COUNTERS|_TIF_NOTIFY_RESUME)

/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW \
diff --git a/arch/x86/include/asm/unistd_32.h b/arch/x86/include/asm/unistd_32.h
index f2bba78..7e47658 100644
--- a/arch/x86/include/asm/unistd_32.h
+++ b/arch/x86/include/asm/unistd_32.h
@@ -338,6 +338,7 @@
#define __NR_dup3 330
#define __NR_pipe2 331
#define __NR_inotify_init1 332
+#define __NR_perf_counter_open 333

#ifdef __KERNEL__

diff --git a/arch/x86/include/asm/unistd_64.h b/arch/x86/include/asm/unistd_64.h
index d2e415e..53025fe 100644
--- a/arch/x86/include/asm/unistd_64.h
+++ b/arch/x86/include/asm/unistd_64.h
@@ -653,7 +653,8 @@ __SYSCALL(__NR_dup3, sys_dup3)
__SYSCALL(__NR_pipe2, sys_pipe2)
#define __NR_inotify_init1 294
__SYSCALL(__NR_inotify_init1, sys_inotify_init1)
-
+#define __NR_perf_counter_open 295
+__SYSCALL(__NR_perf_counter_open, sys_perf_counter_open)

#ifndef __NO_STUBS
#define __ARCH_WANT_OLD_READDIR
diff --git a/arch/x86/kernel/apic.c b/arch/x86/kernel/apic.c
index 16f9487..8ab8c18 100644
--- a/arch/x86/kernel/apic.c
+++ b/arch/x86/kernel/apic.c
@@ -31,6 +31,7 @@
#include <linux/dmi.h>
#include <linux/dmar.h>

+#include <asm/intel_arch_perfmon.h>
#include <asm/atomic.h>
#include <asm/smp.h>
#include <asm/mtrr.h>
@@ -1147,6 +1148,7 @@ void __cpuinit setup_local_APIC(void)
apic_write(APIC_ESR, 0);
}
#endif
+ perf_counters_lapic_init(0);

preempt_disable();

diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 82ec607..89e5336 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -1,5 +1,5 @@
#
-# Makefile for x86-compatible CPU details and quirks
+# Makefile for x86-compatible CPU details, features and quirks
#

obj-y := intel_cacheinfo.o addon_cpuid_features.o
@@ -16,11 +16,13 @@ obj-$(CONFIG_CPU_SUP_CENTAUR_64) += centaur_64.o
obj-$(CONFIG_CPU_SUP_TRANSMETA_32) += transmeta.o
obj-$(CONFIG_CPU_SUP_UMC_32) += umc.o

-obj-$(CONFIG_X86_MCE) += mcheck/
-obj-$(CONFIG_MTRR) += mtrr/
-obj-$(CONFIG_CPU_FREQ) += cpufreq/
+obj-$(CONFIG_PERF_COUNTERS) += perf_counter.o

-obj-$(CONFIG_X86_LOCAL_APIC) += perfctr-watchdog.o
+obj-$(CONFIG_X86_MCE) += mcheck/
+obj-$(CONFIG_MTRR) += mtrr/
+obj-$(CONFIG_CPU_FREQ) += cpufreq/
+
+obj-$(CONFIG_X86_LOCAL_APIC) += perfctr-watchdog.o

quiet_cmd_mkcapflags = MKCAP $@
cmd_mkcapflags = $(PERL) $(srctree)/$(src)/mkcapflags.pl $< $@
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index b9c9ea0..4461011 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -17,6 +17,7 @@
#include <asm/mmu_context.h>
#include <asm/mtrr.h>
#include <asm/mce.h>
+#include <asm/intel_arch_perfmon.h>
#include <asm/pat.h>
#include <asm/asm.h>
#include <asm/numa.h>
@@ -750,6 +751,7 @@ void __init identify_boot_cpu(void)
#else
vgetcpu_set_mode();
#endif
+ init_hw_perf_counters();
}

void __cpuinit identify_secondary_cpu(struct cpuinfo_x86 *c)
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
new file mode 100644
index 0000000..82440cb
--- /dev/null
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -0,0 +1,571 @@
+/*
+ * Performance counter x86 architecture code
+ *
+ * Copyright(C) 2008 Thomas Gleixner <tglx@linutronix.de>
+ * Copyright(C) 2008 Red Hat, Inc., Ingo Molnar
+ *
+ * For licencing details see kernel-base/COPYING
+ */
+
+#include <linux/perf_counter.h>
+#include <linux/capability.h>
+#include <linux/notifier.h>
+#include <linux/hardirq.h>
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/sched.h>
+
+#include <asm/intel_arch_perfmon.h>
+#include <asm/apic.h>
+
+static bool perf_counters_initialized __read_mostly;
+
+/*
+ * Number of (generic) HW counters:
+ */
+static int nr_hw_counters __read_mostly;
+static u32 perf_counter_mask __read_mostly;
+
+/* No support for fixed function counters yet */
+
+#define MAX_HW_COUNTERS 8
+
+struct cpu_hw_counters {
+ struct perf_counter *counters[MAX_HW_COUNTERS];
+ unsigned long used[BITS_TO_LONGS(MAX_HW_COUNTERS)];
+ int enable_all;
+};
+
+/*
+ * Intel PerfMon v3. Used on Core2 and later.
+ */
+static DEFINE_PER_CPU(struct cpu_hw_counters, cpu_hw_counters);
+
+const int intel_perfmon_event_map[] =
+{
+ [PERF_COUNT_CYCLES] = 0x003c,
+ [PERF_COUNT_INSTRUCTIONS] = 0x00c0,
+ [PERF_COUNT_CACHE_REFERENCES] = 0x4f2e,
+ [PERF_COUNT_CACHE_MISSES] = 0x412e,
+ [PERF_COUNT_BRANCH_INSTRUCTIONS] = 0x00c4,
+ [PERF_COUNT_BRANCH_MISSES] = 0x00c5,
+};
+
+const int max_intel_perfmon_events = ARRAY_SIZE(intel_perfmon_event_map);
+
+/*
+ * Setup the hardware configuration for a given hw_event_type
+ */
+int hw_perf_counter_init(struct perf_counter *counter, s32 hw_event_type)
+{
+ struct hw_perf_counter *hwc = &counter->hw;
+
+ if (unlikely(!perf_counters_initialized))
+ return -EINVAL;
+
+ /*
+ * Count user events, and generate PMC IRQs:
+ * (keep 'enabled' bit clear for now)
+ */
+ hwc->config = ARCH_PERFMON_EVENTSEL_USR | ARCH_PERFMON_EVENTSEL_INT;
+
+ /*
+ * If privileged enough, count OS events too, and allow
+ * NMI events as well:
+ */
+ hwc->nmi = 0;
+ if (capable(CAP_SYS_ADMIN)) {
+ hwc->config |= ARCH_PERFMON_EVENTSEL_OS;
+ if (hw_event_type & PERF_COUNT_NMI)
+ hwc->nmi = 1;
+ }
+
+ hwc->config_base = MSR_ARCH_PERFMON_EVENTSEL0;
+ hwc->counter_base = MSR_ARCH_PERFMON_PERFCTR0;
+
+ hwc->irq_period = counter->__irq_period;
+ /*
+ * Intel PMCs cannot be accessed sanely above 32 bit width,
+ * so we install an artificial 1<<31 period regardless of
+ * the generic counter period:
+ */
+ if (!hwc->irq_period)
+ hwc->irq_period = 0x7FFFFFFF;
+
+ hwc->next_count = -((s32) hwc->irq_period);
+
+ /*
+ * Negative event types mean raw encoded event+umask values:
+ */
+ if (hw_event_type < 0) {
+ counter->hw_event_type = -hw_event_type;
+ counter->hw_event_type &= ~PERF_COUNT_NMI;
+ } else {
+ hw_event_type &= ~PERF_COUNT_NMI;
+ if (hw_event_type >= max_intel_perfmon_events)
+ return -EINVAL;
+ /*
+ * The generic map:
+ */
+ counter->hw_event_type = intel_perfmon_event_map[hw_event_type];
+ }
+ hwc->config |= counter->hw_event_type;
+ counter->wakeup_pending = 0;
+
+ return 0;
+}
+
+static void __hw_perf_enable_all(void)
+{
+ wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, perf_counter_mask, 0);
+}
+
+void hw_perf_enable_all(void)
+{
+ struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+
+ cpuc->enable_all = 1;
+ __hw_perf_enable_all();
+}
+
+void hw_perf_disable_all(void)
+{
+ struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+
+ cpuc->enable_all = 0;
+ wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0, 0);
+}
+
+static DEFINE_PER_CPU(u64, prev_next_count[MAX_HW_COUNTERS]);
+
+static void __hw_perf_counter_enable(struct hw_perf_counter *hwc, int idx)
+{
+ per_cpu(prev_next_count[idx], smp_processor_id()) = hwc->next_count;
+
+ wrmsr(hwc->counter_base + idx, hwc->next_count, 0);
+ wrmsr(hwc->config_base + idx, hwc->config, 0);
+}
+
+void hw_perf_counter_enable(struct perf_counter *counter)
+{
+ struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+ struct hw_perf_counter *hwc = &counter->hw;
+ int idx = hwc->idx;
+
+ /* Try to get the previous counter again */
+ if (test_and_set_bit(idx, cpuc->used)) {
+ idx = find_first_zero_bit(cpuc->used, nr_hw_counters);
+ set_bit(idx, cpuc->used);
+ hwc->idx = idx;
+ }
+
+ perf_counters_lapic_init(hwc->nmi);
+
+ wrmsr(hwc->config_base + idx,
+ hwc->config & ~ARCH_PERFMON_EVENTSEL0_ENABLE, 0);
+
+ cpuc->counters[idx] = counter;
+ counter->hw.config |= ARCH_PERFMON_EVENTSEL0_ENABLE;
+ __hw_perf_counter_enable(hwc, idx);
+}
+
+#ifdef CONFIG_X86_64
+static inline void atomic64_counter_set(struct perf_counter *counter, u64 val)
+{
+ atomic64_set(&counter->count, val);
+}
+
+static inline u64 atomic64_counter_read(struct perf_counter *counter)
+{
+ return atomic64_read(&counter->count);
+}
+#else
+/*
+ * Todo: add proper atomic64_t support to 32-bit x86:
+ */
+static inline void atomic64_counter_set(struct perf_counter *counter, u64 val64)
+{
+ u32 *val32 = (void *)&val64;
+
+ atomic_set(counter->count32 + 0, *(val32 + 0));
+ atomic_set(counter->count32 + 1, *(val32 + 1));
+}
+
+static inline u64 atomic64_counter_read(struct perf_counter *counter)
+{
+ return atomic_read(counter->count32 + 0) |
+ (u64) atomic_read(counter->count32 + 1) << 32;
+}
+#endif
+
+static void __hw_perf_save_counter(struct perf_counter *counter,
+ struct hw_perf_counter *hwc, int idx)
+{
+ s64 raw = -1;
+ s64 delta;
+ int err;
+
+ /*
+ * Get the raw hw counter value:
+ */
+ err = rdmsrl_safe(hwc->counter_base + idx, &raw);
+ WARN_ON_ONCE(err);
+
+ /*
+ * Rebase it to zero (it started counting at -irq_period),
+ * to see the delta since ->prev_count:
+ */
+ delta = (s64)hwc->irq_period + (s64)(s32)raw;
+
+ atomic64_counter_set(counter, hwc->prev_count + delta);
+
+ /*
+ * Adjust the ->prev_count offset - if we went beyond
+ * irq_period of units, then we got an IRQ and the counter
+ * was set back to -irq_period:
+ */
+ while (delta >= (s64)hwc->irq_period) {
+ hwc->prev_count += hwc->irq_period;
+ delta -= (s64)hwc->irq_period;
+ }
+
+ /*
+ * Calculate the next raw counter value we'll write into
+ * the counter at the next sched-in time:
+ */
+ delta -= (s64)hwc->irq_period;
+
+ hwc->next_count = (s32)delta;
+}
+
+void perf_counter_print_debug(void)
+{
+ u64 ctrl, status, overflow, pmc_ctrl, pmc_count, next_count;
+ int cpu, err, idx;
+
+ local_irq_disable();
+
+ cpu = smp_processor_id();
+
+ err = rdmsrl_safe(MSR_CORE_PERF_GLOBAL_CTRL, &ctrl);
+ WARN_ON_ONCE(err);
+
+ err = rdmsrl_safe(MSR_CORE_PERF_GLOBAL_STATUS, &status);
+ WARN_ON_ONCE(err);
+
+ err = rdmsrl_safe(MSR_CORE_PERF_GLOBAL_OVF_CTRL, &overflow);
+ WARN_ON_ONCE(err);
+
+ printk(KERN_INFO "\n");
+ printk(KERN_INFO "CPU#%d: ctrl: %016llx\n", cpu, ctrl);
+ printk(KERN_INFO "CPU#%d: status: %016llx\n", cpu, status);
+ printk(KERN_INFO "CPU#%d: overflow: %016llx\n", cpu, overflow);
+
+ for (idx = 0; idx < nr_hw_counters; idx++) {
+ err = rdmsrl_safe(MSR_ARCH_PERFMON_EVENTSEL0 + idx, &pmc_ctrl);
+ WARN_ON_ONCE(err);
+
+ err = rdmsrl_safe(MSR_ARCH_PERFMON_PERFCTR0 + idx, &pmc_count);
+ WARN_ON_ONCE(err);
+
+ next_count = per_cpu(prev_next_count[idx], cpu);
+
+ printk(KERN_INFO "CPU#%d: PMC%d ctrl: %016llx\n",
+ cpu, idx, pmc_ctrl);
+ printk(KERN_INFO "CPU#%d: PMC%d count: %016llx\n",
+ cpu, idx, pmc_count);
+ printk(KERN_INFO "CPU#%d: PMC%d next: %016llx\n",
+ cpu, idx, next_count);
+ }
+ local_irq_enable();
+}
+
+void hw_perf_counter_disable(struct perf_counter *counter)
+{
+ struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+ struct hw_perf_counter *hwc = &counter->hw;
+ unsigned int idx = hwc->idx;
+
+ counter->hw.config &= ~ARCH_PERFMON_EVENTSEL0_ENABLE;
+ wrmsr(hwc->config_base + idx, hwc->config, 0);
+
+ clear_bit(idx, cpuc->used);
+ cpuc->counters[idx] = NULL;
+ __hw_perf_save_counter(counter, hwc, idx);
+}
+
+void hw_perf_counter_read(struct perf_counter *counter)
+{
+ struct hw_perf_counter *hwc = &counter->hw;
+ unsigned long addr = hwc->counter_base + hwc->idx;
+ s64 offs, val = -1LL;
+ s32 val32;
+ int err;
+
+ /* Careful: NMI might modify the counter offset */
+ do {
+ offs = hwc->prev_count;
+ err = rdmsrl_safe(addr, &val);
+ WARN_ON_ONCE(err);
+ } while (offs != hwc->prev_count);
+
+ val32 = (s32) val;
+ val = (s64)hwc->irq_period + (s64)val32;
+ atomic64_counter_set(counter, hwc->prev_count + val);
+}
+
+static void perf_store_irq_data(struct perf_counter *counter, u64 data)
+{
+ struct perf_data *irqdata = counter->irqdata;
+
+ if (irqdata->len > PERF_DATA_BUFLEN - sizeof(u64)) {
+ irqdata->overrun++;
+ } else {
+ u64 *p = (u64 *) &irqdata->data[irqdata->len];
+
+ *p = data;
+ irqdata->len += sizeof(u64);
+ }
+}
+
+static void perf_save_and_restart(struct perf_counter *counter)
+{
+ struct hw_perf_counter *hwc = &counter->hw;
+ int idx = hwc->idx;
+
+ wrmsr(hwc->config_base + idx,
+ hwc->config & ~ARCH_PERFMON_EVENTSEL0_ENABLE, 0);
+
+ if (hwc->config & ARCH_PERFMON_EVENTSEL0_ENABLE) {
+ __hw_perf_save_counter(counter, hwc, idx);
+ __hw_perf_counter_enable(hwc, idx);
+ }
+}
+
+static void
+perf_handle_group(struct perf_counter *leader, u64 *status, u64 *overflown)
+{
+ struct perf_counter_context *ctx = leader->ctx;
+ struct perf_counter *counter;
+ int bit;
+
+ list_for_each_entry(counter, &ctx->counters, list) {
+ if (counter->record_type != PERF_RECORD_SIMPLE ||
+ counter == leader)
+ continue;
+
+ if (counter->active) {
+ /*
+ * When counter was not in the overflow mask, we have to
+ * read it from hardware. We read it as well, when it
+ * has not been read yet and clear the bit in the
+ * status mask.
+ */
+ bit = counter->hw.idx;
+ if (!test_bit(bit, (unsigned long *) overflown) ||
+ test_bit(bit, (unsigned long *) status)) {
+ clear_bit(bit, (unsigned long *) status);
+ perf_save_and_restart(counter);
+ }
+ }
+ perf_store_irq_data(leader, counter->hw_event_type);
+ perf_store_irq_data(leader, atomic64_counter_read(counter));
+ }
+}
+
+/*
+ * This handler is triggered by the local APIC, so the APIC IRQ handling
+ * rules apply:
+ */
+static void __smp_perf_counter_interrupt(struct pt_regs *regs, int nmi)
+{
+ int bit, cpu = smp_processor_id();
+ struct cpu_hw_counters *cpuc;
+ u64 ack, status;
+
+ rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status);
+ if (!status) {
+ ack_APIC_irq();
+ return;
+ }
+
+ /* Disable counters globally */
+ wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0, 0);
+ ack_APIC_irq();
+
+ cpuc = &per_cpu(cpu_hw_counters, cpu);
+
+again:
+ ack = status;
+ for_each_bit(bit, (unsigned long *) &status, nr_hw_counters) {
+ struct perf_counter *counter = cpuc->counters[bit];
+
+ clear_bit(bit, (unsigned long *) &status);
+ if (!counter)
+ continue;
+
+ perf_save_and_restart(counter);
+
+ switch (counter->record_type) {
+ case PERF_RECORD_SIMPLE:
+ continue;
+ case PERF_RECORD_IRQ:
+ perf_store_irq_data(counter, instruction_pointer(regs));
+ break;
+ case PERF_RECORD_GROUP:
+ perf_store_irq_data(counter, counter->hw_event_type);
+ perf_store_irq_data(counter,
+ atomic64_counter_read(counter));
+ perf_handle_group(counter, &status, &ack);
+ break;
+ }
+ /*
+ * From NMI context we cannot call into the scheduler to
+ * do a task wakeup - but we mark these counters as
+ * wakeup_pending and initate a wakeup callback:
+ */
+ if (nmi) {
+ counter->wakeup_pending = 1;
+ set_tsk_thread_flag(current, TIF_PERF_COUNTERS);
+ } else {
+ wake_up(&counter->waitq);
+ }
+ }
+
+ wrmsr(MSR_CORE_PERF_GLOBAL_OVF_CTRL, ack, 0);
+
+ /*
+ * Repeat if there is more work to be done:
+ */
+ rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status);
+ if (status)
+ goto again;
+
+ /*
+ * Do not reenable when global enable is off:
+ */
+ if (cpuc->enable_all)
+ __hw_perf_enable_all();
+}
+
+void smp_perf_counter_interrupt(struct pt_regs *regs)
+{
+ irq_enter();
+#ifdef CONFIG_X86_64
+ add_pda(apic_perf_irqs, 1);
+#else
+ per_cpu(irq_stat, smp_processor_id()).apic_perf_irqs++;
+#endif
+ apic_write(APIC_LVTPC, LOCAL_PERF_VECTOR);
+ __smp_perf_counter_interrupt(regs, 0);
+
+ irq_exit();
+}
+
+/*
+ * This handler is triggered by NMI contexts:
+ */
+void perf_counter_notify(struct pt_regs *regs)
+{
+ struct cpu_hw_counters *cpuc;
+ unsigned long flags;
+ int bit, cpu;
+
+ local_irq_save(flags);
+ cpu = smp_processor_id();
+ cpuc = &per_cpu(cpu_hw_counters, cpu);
+
+ for_each_bit(bit, cpuc->used, nr_hw_counters) {
+ struct perf_counter *counter = cpuc->counters[bit];
+
+ if (!counter)
+ continue;
+
+ if (counter->wakeup_pending) {
+ counter->wakeup_pending = 0;
+ wake_up(&counter->waitq);
+ }
+ }
+
+ local_irq_restore(flags);
+}
+
+void __cpuinit perf_counters_lapic_init(int nmi)
+{
+ u32 apic_val;
+
+ if (!perf_counters_initialized)
+ return;
+ /*
+ * Enable the performance counter vector in the APIC LVT:
+ */
+ apic_val = apic_read(APIC_LVTERR);
+
+ apic_write(APIC_LVTERR, apic_val | APIC_LVT_MASKED);
+ if (nmi)
+ apic_write(APIC_LVTPC, APIC_DM_NMI);
+ else
+ apic_write(APIC_LVTPC, LOCAL_PERF_VECTOR);
+ apic_write(APIC_LVTERR, apic_val);
+}
+
+static int __kprobes
+perf_counter_nmi_handler(struct notifier_block *self,
+ unsigned long cmd, void *__args)
+{
+ struct die_args *args = __args;
+ struct pt_regs *regs;
+
+ if (likely(cmd != DIE_NMI_IPI))
+ return NOTIFY_DONE;
+
+ regs = args->regs;
+
+ apic_write(APIC_LVTPC, APIC_DM_NMI);
+ __smp_perf_counter_interrupt(regs, 1);
+
+ return NOTIFY_STOP;
+}
+
+static __read_mostly struct notifier_block perf_counter_nmi_notifier = {
+ .notifier_call = perf_counter_nmi_handler
+};
+
+void __init init_hw_perf_counters(void)
+{
+ union cpuid10_eax eax;
+ unsigned int unused;
+ unsigned int ebx;
+
+ if (!cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON))
+ return;
+
+ /*
+ * Check whether the Architectural PerfMon supports
+ * Branch Misses Retired Event or not.
+ */
+ cpuid(10, &(eax.full), &ebx, &unused, &unused);
+ if (eax.split.mask_length <= ARCH_PERFMON_BRANCH_MISSES_RETIRED)
+ return;
+
+ printk(KERN_INFO "Intel Performance Monitoring support detected.\n");
+
+ printk(KERN_INFO "... version: %d\n", eax.split.version_id);
+ printk(KERN_INFO "... num_counters: %d\n", eax.split.num_counters);
+ nr_hw_counters = eax.split.num_counters;
+ if (nr_hw_counters > MAX_HW_COUNTERS) {
+ nr_hw_counters = MAX_HW_COUNTERS;
+ WARN(1, KERN_ERR "hw perf counters %d > max(%d), clipping!",
+ nr_hw_counters, MAX_HW_COUNTERS);
+ }
+ perf_counter_mask = (1 << nr_hw_counters) - 1;
+ perf_max_counters = nr_hw_counters;
+
+ printk(KERN_INFO "... bit_width: %d\n", eax.split.bit_width);
+ printk(KERN_INFO "... mask_length: %d\n", eax.split.mask_length);
+
+ perf_counters_lapic_init(0);
+ register_die_notifier(&perf_counter_nmi_notifier);
+
+ perf_counters_initialized = true;
+}
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index b86f332..ad70f59 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -869,6 +869,12 @@ END(error_interrupt)
ENTRY(spurious_interrupt)
apicinterrupt SPURIOUS_APIC_VECTOR,smp_spurious_interrupt
END(spurious_interrupt)
+
+#ifdef CONFIG_PERF_COUNTERS
+ENTRY(perf_counter_interrupt)
+ apicinterrupt LOCAL_PERF_VECTOR,smp_perf_counter_interrupt
+END(perf_counter_interrupt)
+#endif

/*
* Exception entry points.
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index d1d4dc5..d92bc71 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -56,6 +56,10 @@ static int show_other_interrupts(struct seq_file *p)
for_each_online_cpu(j)
seq_printf(p, "%10u ", irq_stats(j)->apic_timer_irqs);
seq_printf(p, " Local timer interrupts\n");
+ seq_printf(p, "CNT: ");
+ for_each_online_cpu(j)
+ seq_printf(p, "%10u ", irq_stats(j)->apic_perf_irqs);
+ seq_printf(p, " Performance counter interrupts\n");
#endif
#ifdef CONFIG_SMP
seq_printf(p, "RES: ");
@@ -160,6 +164,7 @@ u64 arch_irq_stat_cpu(unsigned int cpu)

#ifdef CONFIG_X86_LOCAL_APIC
sum += irq_stats(cpu)->apic_timer_irqs;
+ sum += irq_stats(cpu)->apic_perf_irqs;
#endif
#ifdef CONFIG_SMP
sum += irq_stats(cpu)->irq_resched_count;
diff --git a/arch/x86/kernel/irqinit_32.c b/arch/x86/kernel/irqinit_32.c
index 845aa98..de2bb7c 100644
--- a/arch/x86/kernel/irqinit_32.c
+++ b/arch/x86/kernel/irqinit_32.c
@@ -160,6 +160,9 @@ void __init native_init_IRQ(void)
/* IPI vectors for APIC spurious and error interrupts */
alloc_intr_gate(SPURIOUS_APIC_VECTOR, spurious_interrupt);
alloc_intr_gate(ERROR_APIC_VECTOR, error_interrupt);
+# ifdef CONFIG_PERF_COUNTERS
+ alloc_intr_gate(LOCAL_PERF_VECTOR, perf_counter_interrupt);
+# endif
#endif

#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_MCE_P4THERMAL)
diff --git a/arch/x86/kernel/irqinit_64.c b/arch/x86/kernel/irqinit_64.c
index ff02353..eb04dd9 100644
--- a/arch/x86/kernel/irqinit_64.c
+++ b/arch/x86/kernel/irqinit_64.c
@@ -204,6 +204,11 @@ static void __init apic_intr_init(void)
/* IPI vectors for APIC spurious and error interrupts */
alloc_intr_gate(SPURIOUS_APIC_VECTOR, spurious_interrupt);
alloc_intr_gate(ERROR_APIC_VECTOR, error_interrupt);
+
+ /* Performance monitoring interrupt: */
+#ifdef CONFIG_PERF_COUNTERS
+ alloc_intr_gate(LOCAL_PERF_VECTOR, perf_counter_interrupt);
+#endif
}

void __init native_init_IRQ(void)
diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c
index d6dd057..6d39c27 100644
--- a/arch/x86/kernel/signal_32.c
+++ b/arch/x86/kernel/signal_32.c
@@ -6,7 +6,9 @@
*/
#include <linux/list.h>

+#include <linux/perf_counter.h>
#include <linux/personality.h>
+#include <linux/tracehook.h>
#include <linux/binfmts.h>
#include <linux/suspend.h>
#include <linux/kernel.h>
@@ -17,7 +19,6 @@
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/wait.h>
-#include <linux/tracehook.h>
#include <linux/elf.h>
#include <linux/smp.h>
#include <linux/mm.h>
@@ -694,6 +695,11 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
tracehook_notify_resume(regs);
}

+ if (thread_info_flags & _TIF_PERF_COUNTERS) {
+ clear_thread_flag(TIF_PERF_COUNTERS);
+ perf_counter_notify(regs);
+ }
+
#ifdef CONFIG_X86_32
clear_thread_flag(TIF_IRET);
#endif /* CONFIG_X86_32 */
diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c
index a5c9627..066a13f 100644
--- a/arch/x86/kernel/signal_64.c
+++ b/arch/x86/kernel/signal_64.c
@@ -7,6 +7,7 @@
* 2000-2002 x86-64 support by Andi Kleen
*/

+#include <linux/perf_counter.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
@@ -493,6 +494,10 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
}
+ if (thread_info_flags & _TIF_PERF_COUNTERS) {
+ clear_thread_flag(TIF_PERF_COUNTERS);
+ perf_counter_notify(regs);
+ }

#ifdef CONFIG_X86_32
clear_thread_flag(TIF_IRET);
diff --git a/arch/x86/kernel/syscall_table_32.S b/arch/x86/kernel/syscall_table_32.S
index d44395f..496726d 100644
--- a/arch/x86/kernel/syscall_table_32.S
+++ b/arch/x86/kernel/syscall_table_32.S
@@ -332,3 +332,4 @@ ENTRY(sys_call_table)
.long sys_dup3 /* 330 */
.long sys_pipe2
.long sys_inotify_init1
+ .long sys_perf_counter_open
diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index ce0d9da..52146c2 100644
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -25,6 +25,7 @@
#include <linux/kbd_kern.h>
#include <linux/proc_fs.h>
#include <linux/quotaops.h>
+#include <linux/perf_counter.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/suspend.h>
@@ -244,6 +245,7 @@ static void sysrq_handle_showregs(int key, struct tty_struct *tty)
struct pt_regs *regs = get_irq_regs();
if (regs)
show_regs(regs);
+ perf_counter_print_debug();
}
static struct sysrq_key_op sysrq_showregs_op = {
.handler = sysrq_handle_showregs,
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
new file mode 100644
index 0000000..22c4469
--- /dev/null
+++ b/include/linux/perf_counter.h
@@ -0,0 +1,171 @@
+/*
+ * Performance counters:
+ *
+ * Copyright(C) 2008, Thomas Gleixner <tglx@linutronix.de>
+ * Copyright(C) 2008, Red Hat, Inc., Ingo Molnar
+ *
+ * Data type definitions, declarations, prototypes.
+ *
+ * Started by: Thomas Gleixner and Ingo Molnar
+ *
+ * For licencing details see kernel-base/COPYING
+ */
+#ifndef _LINUX_PERF_COUNTER_H
+#define _LINUX_PERF_COUNTER_H
+
+#include <asm/atomic.h>
+
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include <linux/spinlock.h>
+
+struct task_struct;
+
+/*
+ * Generalized hardware event types, used by the hw_event_type parameter
+ * of the sys_perf_counter_open() syscall:
+ */
+enum hw_event_types {
+ PERF_COUNT_CYCLES,
+ PERF_COUNT_INSTRUCTIONS,
+ PERF_COUNT_CACHE_REFERENCES,
+ PERF_COUNT_CACHE_MISSES,
+ PERF_COUNT_BRANCH_INSTRUCTIONS,
+ PERF_COUNT_BRANCH_MISSES,
+ /*
+ * If this bit is set in the type, then trigger NMI sampling:
+ */
+ PERF_COUNT_NMI = (1 << 30),
+};
+
+/*
+ * IRQ-notification data record type:
+ */
+enum perf_record_type {
+ PERF_RECORD_SIMPLE,
+ PERF_RECORD_IRQ,
+ PERF_RECORD_GROUP,
+};
+
+/**
+ * struct hw_perf_counter - performance counter hardware details
+ */
+struct hw_perf_counter {
+ u64 config;
+ unsigned long config_base;
+ unsigned long counter_base;
+ int nmi;
+ unsigned int idx;
+ u64 prev_count;
+ s32 next_count;
+ u64 irq_period;
+};
+
+/*
+ * Hardcoded buffer length limit for now, for IRQ-fed events:
+ */
+#define PERF_DATA_BUFLEN 2048
+
+/**
+ * struct perf_data - performance counter IRQ data sampling ...
+ */
+struct perf_data {
+ int len;
+ int rd_idx;
+ int overrun;
+ u8 data[PERF_DATA_BUFLEN];
+};
+
+/**
+ * struct perf_counter - performance counter kernel representation:
+ */
+struct perf_counter {
+ struct list_head list;
+ int active;
+#if BITS_PER_LONG == 64
+ atomic64_t count;
+#else
+ atomic_t count32[2];
+#endif
+ u64 __irq_period;
+
+ struct hw_perf_counter hw;
+
+ struct perf_counter_context *ctx;
+ struct task_struct *task;
+
+ /*
+ * Protect attach/detach:
+ */
+ struct mutex mutex;
+
+ int oncpu;
+ int cpu;
+
+ s32 hw_event_type;
+ enum perf_record_type record_type;
+
+ /* read() / irq related data */
+ wait_queue_head_t waitq;
+ /* optional: for NMIs */
+ int wakeup_pending;
+ struct perf_data *irqdata;
+ struct perf_data *usrdata;
+ struct perf_data data[2];
+};
+
+/**
+ * struct perf_counter_context - counter context structure
+ *
+ * Used as a container for task counters and CPU counters as well:
+ */
+struct perf_counter_context {
+#ifdef CONFIG_PERF_COUNTERS
+ /*
+ * Protect the list of counters:
+ */
+ spinlock_t lock;
+ struct list_head counters;
+ int nr_counters;
+ int nr_active;
+ struct task_struct *task;
+#endif
+};
+
+/**
+ * struct perf_counter_cpu_context - per cpu counter context structure
+ */
+struct perf_cpu_context {
+ struct perf_counter_context ctx;
+ struct perf_counter_context *task_ctx;
+ int active_oncpu;
+ int max_pertask;
+};
+
+/*
+ * Set by architecture code:
+ */
+extern int perf_max_counters;
+
+#ifdef CONFIG_PERF_COUNTERS
+extern void perf_counter_task_sched_in(struct task_struct *task, int cpu);
+extern void perf_counter_task_sched_out(struct task_struct *task, int cpu);
+extern void perf_counter_task_tick(struct task_struct *task, int cpu);
+extern void perf_counter_init_task(struct task_struct *task);
+extern void perf_counter_notify(struct pt_regs *regs);
+extern void perf_counter_print_debug(void);
+#else
+static inline void
+perf_counter_task_sched_in(struct task_struct *task, int cpu) { }
+static inline void
+perf_counter_task_sched_out(struct task_struct *task, int cpu) { }
+static inline void
+perf_counter_task_tick(struct task_struct *task, int cpu) { }
+static inline void perf_counter_init_task(struct task_struct *task) { }
+static inline void perf_counter_notify(struct pt_regs *regs) { }
+static inline void perf_counter_print_debug(void) { }
+#endif
+
+#endif /* _LINUX_PERF_COUNTER_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 55e30d1..4c53027 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -71,6 +71,7 @@ struct sched_param {
#include <linux/fs_struct.h>
#include <linux/compiler.h>
#include <linux/completion.h>
+#include <linux/perf_counter.h>
#include <linux/pid.h>
#include <linux/percpu.h>
#include <linux/topology.h>
@@ -1326,6 +1327,7 @@ struct task_struct {
struct list_head pi_state_list;
struct futex_pi_state *pi_state_cache;
#endif
+ struct perf_counter_context perf_counter_ctx;
#ifdef CONFIG_NUMA
struct mempolicy *mempolicy;
short il_next;
@@ -2285,6 +2287,13 @@ static inline void inc_syscw(struct task_struct *tsk)
#define TASK_SIZE_OF(tsk) TASK_SIZE
#endif

+/*
+ * Call the function if the target task is executing on a CPU right now:
+ */
+extern void task_oncpu_function_call(struct task_struct *p,
+ void (*func) (void *info), void *info);
+
+
#ifdef CONFIG_MM_OWNER
extern void mm_update_next_owner(struct mm_struct *mm);
extern void mm_init_owner(struct mm_struct *mm, struct task_struct *p);
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 04fb47b..6cce728 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -624,4 +624,10 @@ asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);

int kernel_execve(const char *filename, char *const argv[], char *const envp[]);

+asmlinkage int
+sys_perf_counter_open(u32 hw_event_type,
+ u32 hw_event_period,
+ u32 record_type,
+ pid_t pid,
+ int cpu);
#endif
diff --git a/init/Kconfig b/init/Kconfig
index f763762..78bede2 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -732,6 +732,35 @@ config AIO
by some high performance threaded applications. Disabling
this option saves about 7k.

+config HAVE_PERF_COUNTERS
+ bool
+
+menu "Performance Counters"
+
+config PERF_COUNTERS
+ bool "Kernel Performance Counters"
+ depends on HAVE_PERF_COUNTERS
+ default y
+ help
+ Enable kernel support for performance counter hardware.
+
+ Performance counters are special hardware registers available
+ on most modern CPUs. These registers count the number of certain
+ types of hw events: such as instructions executed, cachemisses
+ suffered, or branches mis-predicted - without slowing down the
+ kernel or applications. These registers can also trigger interrupts
+ when a threshold number of events have passed - and can thus be
+ used to profile the code that runs on that CPU.
+
+ The Linux Performance Counter subsystem provides an abstraction of
+ these hardware capabilities, available via a system call. It
+ provides per task and per CPU counters, and it provides event
+ capabilities on top of those.
+
+ Say Y if unsure.
+
+endmenu
+
config VM_EVENT_COUNTERS
default y
bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
diff --git a/kernel/Makefile b/kernel/Makefile
index 19fad00..1f184a1 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -89,6 +89,7 @@ obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o
obj-$(CONFIG_FUNCTION_TRACER) += trace/
obj-$(CONFIG_TRACING) += trace/
obj-$(CONFIG_SMP) += sched_cpupri.o
+obj-$(CONFIG_PERF_COUNTERS) += perf_counter.o

ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
diff --git a/kernel/fork.c b/kernel/fork.c
index 2a372a0..441fadf 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -975,6 +975,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
goto fork_out;

rt_mutex_init_task(p);
+ perf_counter_init_task(p);

#ifdef CONFIG_PROVE_LOCKING
DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
new file mode 100644
index 0000000..f84b400
--- /dev/null
+++ b/kernel/perf_counter.c
@@ -0,0 +1,945 @@
+/*
+ * Performance counter core code
+ *
+ * Copyright(C) 2008 Thomas Gleixner <tglx@linutronix.de>
+ * Copyright(C) 2008 Red Hat, Inc., Ingo Molnar
+ *
+ * For licencing details see kernel-base/COPYING
+ */
+
+#include <linux/fs.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <linux/poll.h>
+#include <linux/sysfs.h>
+#include <linux/ptrace.h>
+#include <linux/percpu.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/anon_inodes.h>
+#include <linux/perf_counter.h>
+
+/*
+ * Each CPU has a list of per CPU counters:
+ */
+DEFINE_PER_CPU(struct perf_cpu_context, perf_cpu_context);
+
+int perf_max_counters __read_mostly;
+static int perf_reserved_percpu __read_mostly;
+static int perf_overcommit __read_mostly = 1;
+
+/*
+ * Mutex for (sysadmin-configurable) counter reservations:
+ */
+static DEFINE_MUTEX(perf_resource_mutex);
+
+/*
+ * Architecture provided APIs - weak aliases:
+ */
+
+int __weak hw_perf_counter_init(struct perf_counter *counter, u32 hw_event_type)
+{
+ return -EINVAL;
+}
+
+void __weak hw_perf_counter_enable(struct perf_counter *counter) { }
+void __weak hw_perf_counter_disable(struct perf_counter *counter) { }
+void __weak hw_perf_counter_read(struct perf_counter *counter) { }
+void __weak hw_perf_disable_all(void) { }
+void __weak hw_perf_enable_all(void) { }
+void __weak hw_perf_counter_setup(void) { }
+
+#if BITS_PER_LONG == 64
+
+/*
+ * Read the cached counter in counter safe against cross CPU / NMI
+ * modifications. 64 bit version - no complications.
+ */
+static inline u64 perf_read_counter_safe(struct perf_counter *counter)
+{
+ return (u64) atomic64_read(&counter->count);
+}
+
+#else
+
+/*
+ * Read the cached counter in counter safe against cross CPU / NMI
+ * modifications. 32 bit version.
+ */
+static u64 perf_read_counter_safe(struct perf_counter *counter)
+{
+ u32 cntl, cnth;
+
+ local_irq_disable();
+ do {
+ cnth = atomic_read(&counter->count32[1]);
+ cntl = atomic_read(&counter->count32[0]);
+ } while (cnth != atomic_read(&counter->count32[1]));
+
+ local_irq_enable();
+
+ return cntl | ((u64) cnth) << 32;
+}
+
+#endif
+
+/*
+ * Cross CPU call to remove a performance counter
+ *
+ * We disable the counter on the hardware level first. After that we
+ * remove it from the context list.
+ */
+static void __perf_remove_from_context(void *info)
+{
+ struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+ struct perf_counter *counter = info;
+ struct perf_counter_context *ctx = counter->ctx;
+
+ /*
+ * If this is a task context, we need to check whether it is
+ * the current task context of this cpu. If not it has been
+ * scheduled out before the smp call arrived.
+ */
+ if (ctx->task && cpuctx->task_ctx != ctx)
+ return;
+
+ spin_lock(&ctx->lock);
+
+ if (counter->active) {
+ hw_perf_counter_disable(counter);
+ counter->active = 0;
+ ctx->nr_active--;
+ cpuctx->active_oncpu--;
+ counter->task = NULL;
+ }
+ ctx->nr_counters--;
+
+ /*
+ * Protect the list operation against NMI by disabling the
+ * counters on a global level. NOP for non NMI based counters.
+ */
+ hw_perf_disable_all();
+ list_del_init(&counter->list);
+ hw_perf_enable_all();
+
+ if (!ctx->task) {
+ /*
+ * Allow more per task counters with respect to the
+ * reservation:
+ */
+ cpuctx->max_pertask =
+ min(perf_max_counters - ctx->nr_counters,
+ perf_max_counters - perf_reserved_percpu);
+ }
+
+ spin_unlock(&ctx->lock);
+}
+
+
+/*
+ * Remove the counter from a task's (or a CPU's) list of counters.
+ *
+ * Must be called with counter->mutex held.
+ *
+ * CPU counters are removed with a smp call. For task counters we only
+ * call when the task is on a CPU.
+ */
+static void perf_remove_from_context(struct perf_counter *counter)
+{
+ struct perf_counter_context *ctx = counter->ctx;
+ struct task_struct *task = ctx->task;
+
+ if (!task) {
+ /*
+ * Per cpu counters are removed via an smp call and
+ * the removal is always sucessful.
+ */
+ smp_call_function_single(counter->cpu,
+ __perf_remove_from_context,
+ counter, 1);
+ return;
+ }
+
+retry:
+ task_oncpu_function_call(task, __perf_remove_from_context,
+ counter);
+
+ spin_lock_irq(&ctx->lock);
+ /*
+ * If the context is active we need to retry the smp call.
+ */
+ if (ctx->nr_active && !list_empty(&counter->list)) {
+ spin_unlock_irq(&ctx->lock);
+ goto retry;
+ }
+
+ /*
+ * The lock prevents that this context is scheduled in so we
+ * can remove the counter safely, if it the call above did not
+ * succeed.
+ */
+ if (!list_empty(&counter->list)) {
+ ctx->nr_counters--;
+ list_del_init(&counter->list);
+ counter->task = NULL;
+ }
+ spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Cross CPU call to install and enable a preformance counter
+ */
+static void __perf_install_in_context(void *info)
+{
+ struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+ struct perf_counter *counter = info;
+ struct perf_counter_context *ctx = counter->ctx;
+ int cpu = smp_processor_id();
+
+ /*
+ * If this is a task context, we need to check whether it is
+ * the current task context of this cpu. If not it has been
+ * scheduled out before the smp call arrived.
+ */
+ if (ctx->task && cpuctx->task_ctx != ctx)
+ return;
+
+ spin_lock(&ctx->lock);
+
+ /*
+ * Protect the list operation against NMI by disabling the
+ * counters on a global level. NOP for non NMI based counters.
+ */
+ hw_perf_disable_all();
+ list_add_tail(&counter->list, &ctx->counters);
+ hw_perf_enable_all();
+
+ ctx->nr_counters++;
+
+ if (cpuctx->active_oncpu < perf_max_counters) {
+ hw_perf_counter_enable(counter);
+ counter->active = 1;
+ counter->oncpu = cpu;
+ ctx->nr_active++;
+ cpuctx->active_oncpu++;
+ }
+
+ if (!ctx->task && cpuctx->max_pertask)
+ cpuctx->max_pertask--;
+
+ spin_unlock(&ctx->lock);
+}
+
+/*
+ * Attach a performance counter to a context
+ *
+ * First we add the counter to the list with the hardware enable bit
+ * in counter->hw_config cleared.
+ *
+ * If the counter is attached to a task which is on a CPU we use a smp
+ * call to enable it in the task context. The task might have been
+ * scheduled away, but we check this in the smp call again.
+ */
+static void
+perf_install_in_context(struct perf_counter_context *ctx,
+ struct perf_counter *counter,
+ int cpu)
+{
+ struct task_struct *task = ctx->task;
+
+ counter->ctx = ctx;
+ if (!task) {
+ /*
+ * Per cpu counters are installed via an smp call and
+ * the install is always sucessful.
+ */
+ smp_call_function_single(cpu, __perf_install_in_context,
+ counter, 1);
+ return;
+ }
+
+ counter->task = task;
+retry:
+ task_oncpu_function_call(task, __perf_install_in_context,
+ counter);
+
+ spin_lock_irq(&ctx->lock);
+ /*
+ * If the context is active and the counter has not been added
+ * we need to retry the smp call.
+ */
+ if (ctx->nr_active && list_empty(&counter->list)) {
+ spin_unlock_irq(&ctx->lock);
+ goto retry;
+ }
+
+ /*
+ * The lock prevents that this context is scheduled in so we
+ * can add the counter safely, if it the call above did not
+ * succeed.
+ */
+ if (list_empty(&counter->list)) {
+ list_add_tail(&counter->list, &ctx->counters);
+ ctx->nr_counters++;
+ }
+ spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Called from scheduler to remove the counters of the current task,
+ * with interrupts disabled.
+ *
+ * We stop each counter and update the counter value in counter->count.
+ *
+ * This does not protect us against NMI, but hw_perf_counter_disable()
+ * sets the disabled bit in the control field of counter _before_
+ * accessing the counter control register. If a NMI hits, then it will
+ * not restart the counter.
+ */
+void perf_counter_task_sched_out(struct task_struct *task, int cpu)
+{
+ struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
+ struct perf_counter_context *ctx = &task->perf_counter_ctx;
+ struct perf_counter *counter;
+
+ if (likely(!cpuctx->task_ctx))
+ return;
+
+ spin_lock(&ctx->lock);
+ list_for_each_entry(counter, &ctx->counters, list) {
+ if (!ctx->nr_active)
+ break;
+ if (counter->active) {
+ hw_perf_counter_disable(counter);
+ counter->active = 0;
+ counter->oncpu = -1;
+ ctx->nr_active--;
+ cpuctx->active_oncpu--;
+ }
+ }
+ spin_unlock(&ctx->lock);
+ cpuctx->task_ctx = NULL;
+}
+
+/*
+ * Called from scheduler to add the counters of the current task
+ * with interrupts disabled.
+ *
+ * We restore the counter value and then enable it.
+ *
+ * This does not protect us against NMI, but hw_perf_counter_enable()
+ * sets the enabled bit in the control field of counter _before_
+ * accessing the counter control register. If a NMI hits, then it will
+ * keep the counter running.
+ */
+void perf_counter_task_sched_in(struct task_struct *task, int cpu)
+{
+ struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
+ struct perf_counter_context *ctx = &task->perf_counter_ctx;
+ struct perf_counter *counter;
+
+ if (likely(!ctx->nr_counters))
+ return;
+
+ spin_lock(&ctx->lock);
+ list_for_each_entry(counter, &ctx->counters, list) {
+ if (ctx->nr_active == cpuctx->max_pertask)
+ break;
+ if (counter->cpu != -1 && counter->cpu != cpu)
+ continue;
+
+ hw_perf_counter_enable(counter);
+ counter->active = 1;
+ counter->oncpu = cpu;
+ ctx->nr_active++;
+ cpuctx->active_oncpu++;
+ }
+ spin_unlock(&ctx->lock);
+ cpuctx->task_ctx = ctx;
+}
+
+void perf_counter_task_tick(struct task_struct *curr, int cpu)
+{
+ struct perf_counter_context *ctx = &curr->perf_counter_ctx;
+ struct perf_counter *counter;
+
+ if (likely(!ctx->nr_counters))
+ return;
+
+ perf_counter_task_sched_out(curr, cpu);
+
+ spin_lock(&ctx->lock);
+
+ /*
+ * Rotate the first entry last:
+ */
+ hw_perf_disable_all();
+ list_for_each_entry(counter, &ctx->counters, list) {
+ list_del(&counter->list);
+ list_add_tail(&counter->list, &ctx->counters);
+ break;
+ }
+ hw_perf_enable_all();
+
+ spin_unlock(&ctx->lock);
+
+ perf_counter_task_sched_in(curr, cpu);
+}
+
+/*
+ * Initialize the perf_counter context in task_struct
+ */
+void perf_counter_init_task(struct task_struct *task)
+{
+ struct perf_counter_context *ctx = &task->perf_counter_ctx;
+
+ spin_lock_init(&ctx->lock);
+ INIT_LIST_HEAD(&ctx->counters);
+ ctx->nr_counters = 0;
+ ctx->task = task;
+}
+
+/*
+ * Cross CPU call to read the hardware counter
+ */
+static void __hw_perf_counter_read(void *info)
+{
+ hw_perf_counter_read(info);
+}
+
+static u64 perf_read_counter(struct perf_counter *counter)
+{
+ /*
+ * If counter is enabled and currently active on a CPU, update the
+ * value in the counter structure:
+ */
+ if (counter->active) {
+ smp_call_function_single(counter->oncpu,
+ __hw_perf_counter_read, counter, 1);
+ }
+
+ return perf_read_counter_safe(counter);
+}
+
+/*
+ * Cross CPU call to switch performance data pointers
+ */
+static void __perf_switch_irq_data(void *info)
+{
+ struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+ struct perf_counter *counter = info;
+ struct perf_counter_context *ctx = counter->ctx;
+ struct perf_data *oldirqdata = counter->irqdata;
+
+ /*
+ * If this is a task context, we need to check whether it is
+ * the current task context of this cpu. If not it has been
+ * scheduled out before the smp call arrived.
+ */
+ if (ctx->task) {
+ if (cpuctx->task_ctx != ctx)
+ return;
+ spin_lock(&ctx->lock);
+ }
+
+ /* Change the pointer NMI safe */
+ atomic_long_set((atomic_long_t *)&counter->irqdata,
+ (unsigned long) counter->usrdata);
+ counter->usrdata = oldirqdata;
+
+ if (ctx->task)
+ spin_unlock(&ctx->lock);
+}
+
+static struct perf_data *perf_switch_irq_data(struct perf_counter *counter)
+{
+ struct perf_counter_context *ctx = counter->ctx;
+ struct perf_data *oldirqdata = counter->irqdata;
+ struct task_struct *task = ctx->task;
+
+ if (!task) {
+ smp_call_function_single(counter->cpu,
+ __perf_switch_irq_data,
+ counter, 1);
+ return counter->usrdata;
+ }
+
+retry:
+ spin_lock_irq(&ctx->lock);
+ if (!counter->active) {
+ counter->irqdata = counter->usrdata;
+ counter->usrdata = oldirqdata;
+ spin_unlock_irq(&ctx->lock);
+ return oldirqdata;
+ }
+ spin_unlock_irq(&ctx->lock);
+ task_oncpu_function_call(task, __perf_switch_irq_data, counter);
+ /* Might have failed, because task was scheduled out */
+ if (counter->irqdata == oldirqdata)
+ goto retry;
+
+ return counter->usrdata;
+}
+
+static void put_context(struct perf_counter_context *ctx)
+{
+ if (ctx->task) {
+ put_task_struct(ctx->task);
+ ctx->task = NULL;
+ }
+}
+
+static struct perf_counter_context *find_get_context(pid_t pid, int cpu)
+{
+ struct perf_cpu_context *cpuctx;
+ struct perf_counter_context *ctx;
+ struct task_struct *task;
+
+ /*
+ * If cpu is not a wildcard then this is a percpu counter:
+ */
+ if (cpu != -1) {
+ /* Must be root to operate on a CPU counter: */
+ if (!capable(CAP_SYS_ADMIN))
+ return ERR_PTR(-EACCES);
+
+ if (cpu < 0 || cpu > num_possible_cpus())
+ return ERR_PTR(-EINVAL);
+
+ /*
+ * We could be clever and allow to attach a counter to an
+ * offline CPU and activate it when the CPU comes up, but
+ * that's for later.
+ */
+ if (!cpu_isset(cpu, cpu_online_map))
+ return ERR_PTR(-ENODEV);
+
+ cpuctx = &per_cpu(perf_cpu_context, cpu);
+ ctx = &cpuctx->ctx;
+
+ WARN_ON_ONCE(ctx->task);
+ return ctx;
+ }
+
+ rcu_read_lock();
+ if (!pid)
+ task = current;
+ else
+ task = find_task_by_vpid(pid);
+ if (task)
+ get_task_struct(task);
+ rcu_read_unlock();
+
+ if (!task)
+ return ERR_PTR(-ESRCH);
+
+ ctx = &task->perf_counter_ctx;
+ ctx->task = task;
+
+ /* Reuse ptrace permission checks for now. */
+ if (!ptrace_may_access(task, PTRACE_MODE_READ)) {
+ put_context(ctx);
+ return ERR_PTR(-EACCES);
+ }
+
+ return ctx;
+}
+
+/*
+ * Called when the last reference to the file is gone.
+ */
+static int perf_release(struct inode *inode, struct file *file)
+{
+ struct perf_counter *counter = file->private_data;
+ struct perf_counter_context *ctx = counter->ctx;
+
+ file->private_data = NULL;
+
+ mutex_lock(&counter->mutex);
+
+ perf_remove_from_context(counter);
+ put_context(ctx);
+
+ mutex_unlock(&counter->mutex);
+
+ kfree(counter);
+
+ return 0;
+}
+
+/*
+ * Read the performance counter - simple non blocking version for now
+ */
+static ssize_t
+perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count)
+{
+ u64 cntval;
+
+ if (count != sizeof(cntval))
+ return -EINVAL;
+
+ mutex_lock(&counter->mutex);
+ cntval = perf_read_counter(counter);
+ mutex_unlock(&counter->mutex);
+
+ return put_user(cntval, (u64 __user *) buf) ? -EFAULT : sizeof(cntval);
+}
+
+static ssize_t
+perf_copy_usrdata(struct perf_data *usrdata, char __user *buf, size_t count)
+{
+ if (!usrdata->len)
+ return 0;
+
+ count = min(count, (size_t)usrdata->len);
+ if (copy_to_user(buf, usrdata->data + usrdata->rd_idx, count))
+ return -EFAULT;
+
+ /* Adjust the counters */
+ usrdata->len -= count;
+ if (!usrdata->len)
+ usrdata->rd_idx = 0;
+ else
+ usrdata->rd_idx += count;
+
+ return count;
+}
+
+static ssize_t
+perf_read_irq_data(struct perf_counter *counter,
+ char __user *buf,
+ size_t count,
+ int nonblocking)
+{
+ struct perf_data *irqdata, *usrdata;
+ DECLARE_WAITQUEUE(wait, current);
+ ssize_t res;
+
+ irqdata = counter->irqdata;
+ usrdata = counter->usrdata;
+
+ if (usrdata->len + irqdata->len >= count)
+ goto read_pending;
+
+ if (nonblocking)
+ return -EAGAIN;
+
+ spin_lock_irq(&counter->waitq.lock);
+ __add_wait_queue(&counter->waitq, &wait);
+ for (;;) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (usrdata->len + irqdata->len >= count)
+ break;
+
+ if (signal_pending(current))
+ break;
+
+ spin_unlock_irq(&counter->waitq.lock);
+ schedule();
+ spin_lock_irq(&counter->waitq.lock);
+ }
+ __remove_wait_queue(&counter->waitq, &wait);
+ __set_current_state(TASK_RUNNING);
+ spin_unlock_irq(&counter->waitq.lock);
+
+ if (usrdata->len + irqdata->len < count)
+ return -ERESTARTSYS;
+read_pending:
+ mutex_lock(&counter->mutex);
+
+ /* Drain pending data first: */
+ res = perf_copy_usrdata(usrdata, buf, count);
+ if (res < 0 || res == count)
+ goto out;
+
+ /* Switch irq buffer: */
+ usrdata = perf_switch_irq_data(counter);
+ if (perf_copy_usrdata(usrdata, buf + res, count - res) < 0) {
+ if (!res)
+ res = -EFAULT;
+ } else {
+ res = count;
+ }
+out:
+ mutex_unlock(&counter->mutex);
+
+ return res;
+}
+
+static ssize_t
+perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+ struct perf_counter *counter = file->private_data;
+
+ switch (counter->record_type) {
+ case PERF_RECORD_SIMPLE:
+ return perf_read_hw(counter, buf, count);
+
+ case PERF_RECORD_IRQ:
+ case PERF_RECORD_GROUP:
+ return perf_read_irq_data(counter, buf, count,
+ file->f_flags & O_NONBLOCK);
+ }
+ return -EINVAL;
+}
+
+static unsigned int perf_poll(struct file *file, poll_table *wait)
+{
+ struct perf_counter *counter = file->private_data;
+ unsigned int events = 0;
+ unsigned long flags;
+
+ poll_wait(file, &counter->waitq, wait);
+
+ spin_lock_irqsave(&counter->waitq.lock, flags);
+ if (counter->usrdata->len || counter->irqdata->len)
+ events |= POLLIN;
+ spin_unlock_irqrestore(&counter->waitq.lock, flags);
+
+ return events;
+}
+
+static const struct file_operations perf_fops = {
+ .release = perf_release,
+ .read = perf_read,
+ .poll = perf_poll,
+};
+
+/*
+ * Allocate and initialize a counter structure
+ */
+static struct perf_counter *
+perf_counter_alloc(u32 hw_event_period, int cpu, u32 record_type)
+{
+ struct perf_counter *counter = kzalloc(sizeof(*counter), GFP_KERNEL);
+
+ if (!counter)
+ return NULL;
+
+ mutex_init(&counter->mutex);
+ INIT_LIST_HEAD(&counter->list);
+ init_waitqueue_head(&counter->waitq);
+
+ counter->irqdata = &counter->data[0];
+ counter->usrdata = &counter->data[1];
+ counter->cpu = cpu;
+ counter->record_type = record_type;
+ counter->__irq_period = hw_event_period;
+ counter->wakeup_pending = 0;
+
+ return counter;
+}
+
+/**
+ * sys_perf_task_open - open a performance counter associate it to a task
+ * @hw_event_type: event type for monitoring/sampling...
+ * @pid: target pid
+ */
+asmlinkage int
+sys_perf_counter_open(u32 hw_event_type,
+ u32 hw_event_period,
+ u32 record_type,
+ pid_t pid,
+ int cpu)
+{
+ struct perf_counter_context *ctx;
+ struct perf_counter *counter;
+ int ret;
+
+ ctx = find_get_context(pid, cpu);
+ if (IS_ERR(ctx))
+ return PTR_ERR(ctx);
+
+ ret = -ENOMEM;
+ counter = perf_counter_alloc(hw_event_period, cpu, record_type);
+ if (!counter)
+ goto err_put_context;
+
+ ret = hw_perf_counter_init(counter, hw_event_type);
+ if (ret)
+ goto err_free_put_context;
+
+ perf_install_in_context(ctx, counter, cpu);
+
+ ret = anon_inode_getfd("[perf_counter]", &perf_fops, counter, 0);
+ if (ret < 0)
+ goto err_remove_free_put_context;
+
+ return ret;
+
+err_remove_free_put_context:
+ mutex_lock(&counter->mutex);
+ perf_remove_from_context(counter);
+ mutex_unlock(&counter->mutex);
+
+err_free_put_context:
+ kfree(counter);
+
+err_put_context:
+ put_context(ctx);
+
+ return ret;
+}
+
+static void __cpuinit perf_init_cpu(int cpu)
+{
+ struct perf_cpu_context *ctx;
+
+ ctx = &per_cpu(perf_cpu_context, cpu);
+ spin_lock_init(&ctx->ctx.lock);
+ INIT_LIST_HEAD(&ctx->ctx.counters);
+
+ mutex_lock(&perf_resource_mutex);
+ ctx->max_pertask = perf_max_counters - perf_reserved_percpu;
+ mutex_unlock(&perf_resource_mutex);
+ hw_perf_counter_setup();
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void __perf_exit_cpu(void *info)
+{
+ struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+ struct perf_counter_context *ctx = &cpuctx->ctx;
+ struct perf_counter *counter, *tmp;
+
+ list_for_each_entry_safe(counter, tmp, &ctx->counters, list)
+ __perf_remove_from_context(counter);
+
+}
+static void perf_exit_cpu(int cpu)
+{
+ smp_call_function_single(cpu, __perf_exit_cpu, NULL, 1);
+}
+#else
+static inline void perf_exit_cpu(int cpu) { }
+#endif
+
+static int __cpuinit
+perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (long)hcpu;
+
+ switch (action) {
+
+ case CPU_UP_PREPARE:
+ case CPU_UP_PREPARE_FROZEN:
+ perf_init_cpu(cpu);
+ break;
+
+ case CPU_DOWN_PREPARE:
+ case CPU_DOWN_PREPARE_FROZEN:
+ perf_exit_cpu(cpu);
+ break;
+
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata perf_cpu_nb = {
+ .notifier_call = perf_cpu_notify,
+};
+
+static int __init perf_counter_init(void)
+{
+ perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_UP_PREPARE,
+ (void *)(long)smp_processor_id());
+ register_cpu_notifier(&perf_cpu_nb);
+
+ return 0;
+}
+early_initcall(perf_counter_init);
+
+static ssize_t perf_show_reserve_percpu(struct sysdev_class *class, char *buf)
+{
+ return sprintf(buf, "%d\n", perf_reserved_percpu);
+}
+
+static ssize_t
+perf_set_reserve_percpu(struct sysdev_class *class,
+ const char *buf,
+ size_t count)
+{
+ struct perf_cpu_context *cpuctx;
+ unsigned long val;
+ int err, cpu, mpt;
+
+ err = strict_strtoul(buf, 10, &val);
+ if (err)
+ return err;
+ if (val > perf_max_counters)
+ return -EINVAL;
+
+ mutex_lock(&perf_resource_mutex);
+ perf_reserved_percpu = val;
+ for_each_online_cpu(cpu) {
+ cpuctx = &per_cpu(perf_cpu_context, cpu);
+ spin_lock_irq(&cpuctx->ctx.lock);
+ mpt = min(perf_max_counters - cpuctx->ctx.nr_counters,
+ perf_max_counters - perf_reserved_percpu);
+ cpuctx->max_pertask = mpt;
+ spin_unlock_irq(&cpuctx->ctx.lock);
+ }
+ mutex_unlock(&perf_resource_mutex);
+
+ return count;
+}
+
+static ssize_t perf_show_overcommit(struct sysdev_class *class, char *buf)
+{
+ return sprintf(buf, "%d\n", perf_overcommit);
+}
+
+static ssize_t
+perf_set_overcommit(struct sysdev_class *class, const char *buf, size_t count)
+{
+ unsigned long val;
+ int err;
+
+ err = strict_strtoul(buf, 10, &val);
+ if (err)
+ return err;
+ if (val > 1)
+ return -EINVAL;
+
+ mutex_lock(&perf_resource_mutex);
+ perf_overcommit = val;
+ mutex_unlock(&perf_resource_mutex);
+
+ return count;
+}
+
+static SYSDEV_CLASS_ATTR(
+ reserve_percpu,
+ 0644,
+ perf_show_reserve_percpu,
+ perf_set_reserve_percpu
+ );
+
+static SYSDEV_CLASS_ATTR(
+ overcommit,
+ 0644,
+ perf_show_overcommit,
+ perf_set_overcommit
+ );
+
+static struct attribute *perfclass_attrs[] = {
+ &attr_reserve_percpu.attr,
+ &attr_overcommit.attr,
+ NULL
+};
+
+static struct attribute_group perfclass_attr_group = {
+ .attrs = perfclass_attrs,
+ .name = "perf_counters",
+};
+
+static int __init perf_counter_sysfs_init(void)
+{
+ return sysfs_create_group(&cpu_sysdev_class.kset.kobj,
+ &perfclass_attr_group);
+}
+device_initcall(perf_counter_sysfs_init);
+
diff --git a/kernel/sched.c b/kernel/sched.c
index b7480fb..254d56d 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2212,6 +2212,27 @@ static int sched_balance_self(int cpu, int flag)

#endif /* CONFIG_SMP */

+/**
+ * task_oncpu_function_call - call a function on the cpu on which a task runs
+ * @p: the task to evaluate
+ * @func: the function to be called
+ * @info: the function call argument
+ *
+ * Calls the function @func when the task is currently running. This might
+ * be on the current CPU, which just calls the function directly
+ */
+void task_oncpu_function_call(struct task_struct *p,
+ void (*func) (void *info), void *info)
+{
+ int cpu;
+
+ preempt_disable();
+ cpu = task_cpu(p);
+ if (task_curr(p))
+ smp_call_function_single(cpu, func, info, 1);
+ preempt_enable();
+}
+
/***
* try_to_wake_up - wake up a thread
* @p: the to-be-woken-up thread
@@ -2534,6 +2555,7 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev,
struct task_struct *next)
{
fire_sched_out_preempt_notifiers(prev, next);
+ perf_counter_task_sched_out(prev, cpu_of(rq));
prepare_lock_switch(rq, next);
prepare_arch_switch(next);
}
@@ -2574,6 +2596,7 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev)
*/
prev_state = prev->state;
finish_arch_switch(prev);
+ perf_counter_task_sched_in(current, cpu_of(rq));
finish_lock_switch(rq, prev);
#ifdef CONFIG_SMP
if (current->sched_class->post_schedule)
@@ -4296,6 +4319,7 @@ void scheduler_tick(void)
rq->idle_at_tick = idle_cpu(cpu);
trigger_load_balance(rq, cpu);
#endif
+ perf_counter_task_tick(curr, cpu);
}

#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index e14a232..4be8bbc 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -174,3 +174,6 @@ cond_syscall(compat_sys_timerfd_settime);
cond_syscall(compat_sys_timerfd_gettime);
cond_syscall(sys_eventfd);
cond_syscall(sys_eventfd2);
+
+/* performance counters: */
+cond_syscall(sys_perf_counter_open);

\
 
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  Last update: 2008-12-08 02:25    [W:0.524 / U:0.276 seconds]
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