kernel-ark/kernel/profile.c
Linus Torvalds 467a9e1633 CPU hotplug notifiers registration fixes for 3.15-rc1
The purpose of this single series of commits from Srivatsa S Bhat (with
 a small piece from Gautham R Shenoy) touching multiple subsystems that use
 CPU hotplug notifiers is to provide a way to register them that will not
 lead to deadlocks with CPU online/offline operations as described in the
 changelog of commit 93ae4f978c (CPU hotplug: Provide lockless versions
 of callback registration functions).
 
 The first three commits in the series introduce the API and document it
 and the rest simply goes through the users of CPU hotplug notifiers and
 converts them to using the new method.
 
 /
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Merge tag 'cpu-hotplug-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull CPU hotplug notifiers registration fixes from Rafael Wysocki:
 "The purpose of this single series of commits from Srivatsa S Bhat
  (with a small piece from Gautham R Shenoy) touching multiple
  subsystems that use CPU hotplug notifiers is to provide a way to
  register them that will not lead to deadlocks with CPU online/offline
  operations as described in the changelog of commit 93ae4f978c ("CPU
  hotplug: Provide lockless versions of callback registration
  functions").

  The first three commits in the series introduce the API and document
  it and the rest simply goes through the users of CPU hotplug notifiers
  and converts them to using the new method"

* tag 'cpu-hotplug-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (52 commits)
  net/iucv/iucv.c: Fix CPU hotplug callback registration
  net/core/flow.c: Fix CPU hotplug callback registration
  mm, zswap: Fix CPU hotplug callback registration
  mm, vmstat: Fix CPU hotplug callback registration
  profile: Fix CPU hotplug callback registration
  trace, ring-buffer: Fix CPU hotplug callback registration
  xen, balloon: Fix CPU hotplug callback registration
  hwmon, via-cputemp: Fix CPU hotplug callback registration
  hwmon, coretemp: Fix CPU hotplug callback registration
  thermal, x86-pkg-temp: Fix CPU hotplug callback registration
  octeon, watchdog: Fix CPU hotplug callback registration
  oprofile, nmi-timer: Fix CPU hotplug callback registration
  intel-idle: Fix CPU hotplug callback registration
  clocksource, dummy-timer: Fix CPU hotplug callback registration
  drivers/base/topology.c: Fix CPU hotplug callback registration
  acpi-cpufreq: Fix CPU hotplug callback registration
  zsmalloc: Fix CPU hotplug callback registration
  scsi, fcoe: Fix CPU hotplug callback registration
  scsi, bnx2fc: Fix CPU hotplug callback registration
  scsi, bnx2i: Fix CPU hotplug callback registration
  ...
2014-04-07 14:55:46 -07:00

619 lines
16 KiB
C

/*
* linux/kernel/profile.c
* Simple profiling. Manages a direct-mapped profile hit count buffer,
* with configurable resolution, support for restricting the cpus on
* which profiling is done, and switching between cpu time and
* schedule() calls via kernel command line parameters passed at boot.
*
* Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
* Red Hat, July 2004
* Consolidation of architecture support code for profiling,
* Nadia Yvette Chambers, Oracle, July 2004
* Amortized hit count accounting via per-cpu open-addressed hashtables
* to resolve timer interrupt livelocks, Nadia Yvette Chambers,
* Oracle, 2004
*/
#include <linux/export.h>
#include <linux/profile.h>
#include <linux/bootmem.h>
#include <linux/notifier.h>
#include <linux/mm.h>
#include <linux/cpumask.h>
#include <linux/cpu.h>
#include <linux/highmem.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <asm/sections.h>
#include <asm/irq_regs.h>
#include <asm/ptrace.h>
struct profile_hit {
u32 pc, hits;
};
#define PROFILE_GRPSHIFT 3
#define PROFILE_GRPSZ (1 << PROFILE_GRPSHIFT)
#define NR_PROFILE_HIT (PAGE_SIZE/sizeof(struct profile_hit))
#define NR_PROFILE_GRP (NR_PROFILE_HIT/PROFILE_GRPSZ)
static atomic_t *prof_buffer;
static unsigned long prof_len, prof_shift;
int prof_on __read_mostly;
EXPORT_SYMBOL_GPL(prof_on);
static cpumask_var_t prof_cpu_mask;
#ifdef CONFIG_SMP
static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
static DEFINE_PER_CPU(int, cpu_profile_flip);
static DEFINE_MUTEX(profile_flip_mutex);
#endif /* CONFIG_SMP */
int profile_setup(char *str)
{
static char schedstr[] = "schedule";
static char sleepstr[] = "sleep";
static char kvmstr[] = "kvm";
int par;
if (!strncmp(str, sleepstr, strlen(sleepstr))) {
#ifdef CONFIG_SCHEDSTATS
prof_on = SLEEP_PROFILING;
if (str[strlen(sleepstr)] == ',')
str += strlen(sleepstr) + 1;
if (get_option(&str, &par))
prof_shift = par;
printk(KERN_INFO
"kernel sleep profiling enabled (shift: %ld)\n",
prof_shift);
#else
printk(KERN_WARNING
"kernel sleep profiling requires CONFIG_SCHEDSTATS\n");
#endif /* CONFIG_SCHEDSTATS */
} else if (!strncmp(str, schedstr, strlen(schedstr))) {
prof_on = SCHED_PROFILING;
if (str[strlen(schedstr)] == ',')
str += strlen(schedstr) + 1;
if (get_option(&str, &par))
prof_shift = par;
printk(KERN_INFO
"kernel schedule profiling enabled (shift: %ld)\n",
prof_shift);
} else if (!strncmp(str, kvmstr, strlen(kvmstr))) {
prof_on = KVM_PROFILING;
if (str[strlen(kvmstr)] == ',')
str += strlen(kvmstr) + 1;
if (get_option(&str, &par))
prof_shift = par;
printk(KERN_INFO
"kernel KVM profiling enabled (shift: %ld)\n",
prof_shift);
} else if (get_option(&str, &par)) {
prof_shift = par;
prof_on = CPU_PROFILING;
printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n",
prof_shift);
}
return 1;
}
__setup("profile=", profile_setup);
int __ref profile_init(void)
{
int buffer_bytes;
if (!prof_on)
return 0;
/* only text is profiled */
prof_len = (_etext - _stext) >> prof_shift;
buffer_bytes = prof_len*sizeof(atomic_t);
if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
return -ENOMEM;
cpumask_copy(prof_cpu_mask, cpu_possible_mask);
prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);
if (prof_buffer)
return 0;
prof_buffer = alloc_pages_exact(buffer_bytes,
GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
if (prof_buffer)
return 0;
prof_buffer = vzalloc(buffer_bytes);
if (prof_buffer)
return 0;
free_cpumask_var(prof_cpu_mask);
return -ENOMEM;
}
/* Profile event notifications */
static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
void profile_task_exit(struct task_struct *task)
{
blocking_notifier_call_chain(&task_exit_notifier, 0, task);
}
int profile_handoff_task(struct task_struct *task)
{
int ret;
ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
return (ret == NOTIFY_OK) ? 1 : 0;
}
void profile_munmap(unsigned long addr)
{
blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
}
int task_handoff_register(struct notifier_block *n)
{
return atomic_notifier_chain_register(&task_free_notifier, n);
}
EXPORT_SYMBOL_GPL(task_handoff_register);
int task_handoff_unregister(struct notifier_block *n)
{
return atomic_notifier_chain_unregister(&task_free_notifier, n);
}
EXPORT_SYMBOL_GPL(task_handoff_unregister);
int profile_event_register(enum profile_type type, struct notifier_block *n)
{
int err = -EINVAL;
switch (type) {
case PROFILE_TASK_EXIT:
err = blocking_notifier_chain_register(
&task_exit_notifier, n);
break;
case PROFILE_MUNMAP:
err = blocking_notifier_chain_register(
&munmap_notifier, n);
break;
}
return err;
}
EXPORT_SYMBOL_GPL(profile_event_register);
int profile_event_unregister(enum profile_type type, struct notifier_block *n)
{
int err = -EINVAL;
switch (type) {
case PROFILE_TASK_EXIT:
err = blocking_notifier_chain_unregister(
&task_exit_notifier, n);
break;
case PROFILE_MUNMAP:
err = blocking_notifier_chain_unregister(
&munmap_notifier, n);
break;
}
return err;
}
EXPORT_SYMBOL_GPL(profile_event_unregister);
#ifdef CONFIG_SMP
/*
* Each cpu has a pair of open-addressed hashtables for pending
* profile hits. read_profile() IPI's all cpus to request them
* to flip buffers and flushes their contents to prof_buffer itself.
* Flip requests are serialized by the profile_flip_mutex. The sole
* use of having a second hashtable is for avoiding cacheline
* contention that would otherwise happen during flushes of pending
* profile hits required for the accuracy of reported profile hits
* and so resurrect the interrupt livelock issue.
*
* The open-addressed hashtables are indexed by profile buffer slot
* and hold the number of pending hits to that profile buffer slot on
* a cpu in an entry. When the hashtable overflows, all pending hits
* are accounted to their corresponding profile buffer slots with
* atomic_add() and the hashtable emptied. As numerous pending hits
* may be accounted to a profile buffer slot in a hashtable entry,
* this amortizes a number of atomic profile buffer increments likely
* to be far larger than the number of entries in the hashtable,
* particularly given that the number of distinct profile buffer
* positions to which hits are accounted during short intervals (e.g.
* several seconds) is usually very small. Exclusion from buffer
* flipping is provided by interrupt disablement (note that for
* SCHED_PROFILING or SLEEP_PROFILING profile_hit() may be called from
* process context).
* The hash function is meant to be lightweight as opposed to strong,
* and was vaguely inspired by ppc64 firmware-supported inverted
* pagetable hash functions, but uses a full hashtable full of finite
* collision chains, not just pairs of them.
*
* -- nyc
*/
static void __profile_flip_buffers(void *unused)
{
int cpu = smp_processor_id();
per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
}
static void profile_flip_buffers(void)
{
int i, j, cpu;
mutex_lock(&profile_flip_mutex);
j = per_cpu(cpu_profile_flip, get_cpu());
put_cpu();
on_each_cpu(__profile_flip_buffers, NULL, 1);
for_each_online_cpu(cpu) {
struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
for (i = 0; i < NR_PROFILE_HIT; ++i) {
if (!hits[i].hits) {
if (hits[i].pc)
hits[i].pc = 0;
continue;
}
atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
hits[i].hits = hits[i].pc = 0;
}
}
mutex_unlock(&profile_flip_mutex);
}
static void profile_discard_flip_buffers(void)
{
int i, cpu;
mutex_lock(&profile_flip_mutex);
i = per_cpu(cpu_profile_flip, get_cpu());
put_cpu();
on_each_cpu(__profile_flip_buffers, NULL, 1);
for_each_online_cpu(cpu) {
struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
}
mutex_unlock(&profile_flip_mutex);
}
static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
{
unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
int i, j, cpu;
struct profile_hit *hits;
pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
cpu = get_cpu();
hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
if (!hits) {
put_cpu();
return;
}
/*
* We buffer the global profiler buffer into a per-CPU
* queue and thus reduce the number of global (and possibly
* NUMA-alien) accesses. The write-queue is self-coalescing:
*/
local_irq_save(flags);
do {
for (j = 0; j < PROFILE_GRPSZ; ++j) {
if (hits[i + j].pc == pc) {
hits[i + j].hits += nr_hits;
goto out;
} else if (!hits[i + j].hits) {
hits[i + j].pc = pc;
hits[i + j].hits = nr_hits;
goto out;
}
}
i = (i + secondary) & (NR_PROFILE_HIT - 1);
} while (i != primary);
/*
* Add the current hit(s) and flush the write-queue out
* to the global buffer:
*/
atomic_add(nr_hits, &prof_buffer[pc]);
for (i = 0; i < NR_PROFILE_HIT; ++i) {
atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
hits[i].pc = hits[i].hits = 0;
}
out:
local_irq_restore(flags);
put_cpu();
}
static int profile_cpu_callback(struct notifier_block *info,
unsigned long action, void *__cpu)
{
int node, cpu = (unsigned long)__cpu;
struct page *page;
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
node = cpu_to_mem(cpu);
per_cpu(cpu_profile_flip, cpu) = 0;
if (!per_cpu(cpu_profile_hits, cpu)[1]) {
page = alloc_pages_exact_node(node,
GFP_KERNEL | __GFP_ZERO,
0);
if (!page)
return notifier_from_errno(-ENOMEM);
per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
}
if (!per_cpu(cpu_profile_hits, cpu)[0]) {
page = alloc_pages_exact_node(node,
GFP_KERNEL | __GFP_ZERO,
0);
if (!page)
goto out_free;
per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
}
break;
out_free:
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
per_cpu(cpu_profile_hits, cpu)[1] = NULL;
__free_page(page);
return notifier_from_errno(-ENOMEM);
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
if (prof_cpu_mask != NULL)
cpumask_set_cpu(cpu, prof_cpu_mask);
break;
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
case CPU_DEAD:
case CPU_DEAD_FROZEN:
if (prof_cpu_mask != NULL)
cpumask_clear_cpu(cpu, prof_cpu_mask);
if (per_cpu(cpu_profile_hits, cpu)[0]) {
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
per_cpu(cpu_profile_hits, cpu)[0] = NULL;
__free_page(page);
}
if (per_cpu(cpu_profile_hits, cpu)[1]) {
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
per_cpu(cpu_profile_hits, cpu)[1] = NULL;
__free_page(page);
}
break;
}
return NOTIFY_OK;
}
#else /* !CONFIG_SMP */
#define profile_flip_buffers() do { } while (0)
#define profile_discard_flip_buffers() do { } while (0)
#define profile_cpu_callback NULL
static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
{
unsigned long pc;
pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);
}
#endif /* !CONFIG_SMP */
void profile_hits(int type, void *__pc, unsigned int nr_hits)
{
if (prof_on != type || !prof_buffer)
return;
do_profile_hits(type, __pc, nr_hits);
}
EXPORT_SYMBOL_GPL(profile_hits);
void profile_tick(int type)
{
struct pt_regs *regs = get_irq_regs();
if (!user_mode(regs) && prof_cpu_mask != NULL &&
cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
profile_hit(type, (void *)profile_pc(regs));
}
#ifdef CONFIG_PROC_FS
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <asm/uaccess.h>
static int prof_cpu_mask_proc_show(struct seq_file *m, void *v)
{
seq_cpumask(m, prof_cpu_mask);
seq_putc(m, '\n');
return 0;
}
static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file)
{
return single_open(file, prof_cpu_mask_proc_show, NULL);
}
static ssize_t prof_cpu_mask_proc_write(struct file *file,
const char __user *buffer, size_t count, loff_t *pos)
{
cpumask_var_t new_value;
int err;
if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
return -ENOMEM;
err = cpumask_parse_user(buffer, count, new_value);
if (!err) {
cpumask_copy(prof_cpu_mask, new_value);
err = count;
}
free_cpumask_var(new_value);
return err;
}
static const struct file_operations prof_cpu_mask_proc_fops = {
.open = prof_cpu_mask_proc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
.write = prof_cpu_mask_proc_write,
};
void create_prof_cpu_mask(void)
{
/* create /proc/irq/prof_cpu_mask */
proc_create("irq/prof_cpu_mask", 0600, NULL, &prof_cpu_mask_proc_fops);
}
/*
* This function accesses profiling information. The returned data is
* binary: the sampling step and the actual contents of the profile
* buffer. Use of the program readprofile is recommended in order to
* get meaningful info out of these data.
*/
static ssize_t
read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
ssize_t read;
char *pnt;
unsigned int sample_step = 1 << prof_shift;
profile_flip_buffers();
if (p >= (prof_len+1)*sizeof(unsigned int))
return 0;
if (count > (prof_len+1)*sizeof(unsigned int) - p)
count = (prof_len+1)*sizeof(unsigned int) - p;
read = 0;
while (p < sizeof(unsigned int) && count > 0) {
if (put_user(*((char *)(&sample_step)+p), buf))
return -EFAULT;
buf++; p++; count--; read++;
}
pnt = (char *)prof_buffer + p - sizeof(atomic_t);
if (copy_to_user(buf, (void *)pnt, count))
return -EFAULT;
read += count;
*ppos += read;
return read;
}
/*
* Writing to /proc/profile resets the counters
*
* Writing a 'profiling multiplier' value into it also re-sets the profiling
* interrupt frequency, on architectures that support this.
*/
static ssize_t write_profile(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
#ifdef CONFIG_SMP
extern int setup_profiling_timer(unsigned int multiplier);
if (count == sizeof(int)) {
unsigned int multiplier;
if (copy_from_user(&multiplier, buf, sizeof(int)))
return -EFAULT;
if (setup_profiling_timer(multiplier))
return -EINVAL;
}
#endif
profile_discard_flip_buffers();
memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
return count;
}
static const struct file_operations proc_profile_operations = {
.read = read_profile,
.write = write_profile,
.llseek = default_llseek,
};
#ifdef CONFIG_SMP
static void profile_nop(void *unused)
{
}
static int create_hash_tables(void)
{
int cpu;
for_each_online_cpu(cpu) {
int node = cpu_to_mem(cpu);
struct page *page;
page = alloc_pages_exact_node(node,
GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
0);
if (!page)
goto out_cleanup;
per_cpu(cpu_profile_hits, cpu)[1]
= (struct profile_hit *)page_address(page);
page = alloc_pages_exact_node(node,
GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
0);
if (!page)
goto out_cleanup;
per_cpu(cpu_profile_hits, cpu)[0]
= (struct profile_hit *)page_address(page);
}
return 0;
out_cleanup:
prof_on = 0;
smp_mb();
on_each_cpu(profile_nop, NULL, 1);
for_each_online_cpu(cpu) {
struct page *page;
if (per_cpu(cpu_profile_hits, cpu)[0]) {
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
per_cpu(cpu_profile_hits, cpu)[0] = NULL;
__free_page(page);
}
if (per_cpu(cpu_profile_hits, cpu)[1]) {
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
per_cpu(cpu_profile_hits, cpu)[1] = NULL;
__free_page(page);
}
}
return -1;
}
#else
#define create_hash_tables() ({ 0; })
#endif
int __ref create_proc_profile(void) /* false positive from hotcpu_notifier */
{
struct proc_dir_entry *entry;
int err = 0;
if (!prof_on)
return 0;
cpu_notifier_register_begin();
if (create_hash_tables()) {
err = -ENOMEM;
goto out;
}
entry = proc_create("profile", S_IWUSR | S_IRUGO,
NULL, &proc_profile_operations);
if (!entry)
goto out;
proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));
__hotcpu_notifier(profile_cpu_callback, 0);
out:
cpu_notifier_register_done();
return err;
}
subsys_initcall(create_proc_profile);
#endif /* CONFIG_PROC_FS */