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![Sebastian Andrzej Siewior](/assets/img/avatar_default.png)
Install the callbacks via the state machine and let the core invoke the callbacks on the already online CPUs. A lot of code is removed because the for-loop is used and create_hash_tables() is removed since its purpose is covered by the startup / teardown hooks. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153337.649867675@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
563 lines
15 KiB
C
563 lines
15 KiB
C
/*
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* linux/kernel/profile.c
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* Simple profiling. Manages a direct-mapped profile hit count buffer,
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* with configurable resolution, support for restricting the cpus on
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* which profiling is done, and switching between cpu time and
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* schedule() calls via kernel command line parameters passed at boot.
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*
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* Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
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* Red Hat, July 2004
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* Consolidation of architecture support code for profiling,
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* Nadia Yvette Chambers, Oracle, July 2004
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* Amortized hit count accounting via per-cpu open-addressed hashtables
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* to resolve timer interrupt livelocks, Nadia Yvette Chambers,
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* Oracle, 2004
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*/
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#include <linux/export.h>
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#include <linux/profile.h>
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#include <linux/bootmem.h>
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#include <linux/notifier.h>
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#include <linux/mm.h>
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#include <linux/cpumask.h>
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#include <linux/cpu.h>
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#include <linux/highmem.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <asm/sections.h>
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#include <asm/irq_regs.h>
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#include <asm/ptrace.h>
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struct profile_hit {
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u32 pc, hits;
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};
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#define PROFILE_GRPSHIFT 3
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#define PROFILE_GRPSZ (1 << PROFILE_GRPSHIFT)
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#define NR_PROFILE_HIT (PAGE_SIZE/sizeof(struct profile_hit))
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#define NR_PROFILE_GRP (NR_PROFILE_HIT/PROFILE_GRPSZ)
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static atomic_t *prof_buffer;
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static unsigned long prof_len, prof_shift;
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int prof_on __read_mostly;
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EXPORT_SYMBOL_GPL(prof_on);
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static cpumask_var_t prof_cpu_mask;
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#if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
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static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
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static DEFINE_PER_CPU(int, cpu_profile_flip);
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static DEFINE_MUTEX(profile_flip_mutex);
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#endif /* CONFIG_SMP */
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int profile_setup(char *str)
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{
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static const char schedstr[] = "schedule";
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static const char sleepstr[] = "sleep";
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static const char kvmstr[] = "kvm";
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int par;
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if (!strncmp(str, sleepstr, strlen(sleepstr))) {
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#ifdef CONFIG_SCHEDSTATS
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force_schedstat_enabled();
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prof_on = SLEEP_PROFILING;
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if (str[strlen(sleepstr)] == ',')
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str += strlen(sleepstr) + 1;
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if (get_option(&str, &par))
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prof_shift = par;
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pr_info("kernel sleep profiling enabled (shift: %ld)\n",
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prof_shift);
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#else
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pr_warn("kernel sleep profiling requires CONFIG_SCHEDSTATS\n");
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#endif /* CONFIG_SCHEDSTATS */
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} else if (!strncmp(str, schedstr, strlen(schedstr))) {
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prof_on = SCHED_PROFILING;
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if (str[strlen(schedstr)] == ',')
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str += strlen(schedstr) + 1;
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if (get_option(&str, &par))
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prof_shift = par;
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pr_info("kernel schedule profiling enabled (shift: %ld)\n",
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prof_shift);
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} else if (!strncmp(str, kvmstr, strlen(kvmstr))) {
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prof_on = KVM_PROFILING;
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if (str[strlen(kvmstr)] == ',')
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str += strlen(kvmstr) + 1;
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if (get_option(&str, &par))
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prof_shift = par;
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pr_info("kernel KVM profiling enabled (shift: %ld)\n",
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prof_shift);
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} else if (get_option(&str, &par)) {
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prof_shift = par;
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prof_on = CPU_PROFILING;
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pr_info("kernel profiling enabled (shift: %ld)\n",
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prof_shift);
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}
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return 1;
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}
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__setup("profile=", profile_setup);
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int __ref profile_init(void)
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{
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int buffer_bytes;
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if (!prof_on)
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return 0;
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/* only text is profiled */
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prof_len = (_etext - _stext) >> prof_shift;
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buffer_bytes = prof_len*sizeof(atomic_t);
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if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
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return -ENOMEM;
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cpumask_copy(prof_cpu_mask, cpu_possible_mask);
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prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);
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if (prof_buffer)
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return 0;
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prof_buffer = alloc_pages_exact(buffer_bytes,
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GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
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if (prof_buffer)
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return 0;
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prof_buffer = vzalloc(buffer_bytes);
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if (prof_buffer)
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return 0;
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free_cpumask_var(prof_cpu_mask);
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return -ENOMEM;
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}
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/* Profile event notifications */
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static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
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static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
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static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
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void profile_task_exit(struct task_struct *task)
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{
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blocking_notifier_call_chain(&task_exit_notifier, 0, task);
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}
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int profile_handoff_task(struct task_struct *task)
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{
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int ret;
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ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
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return (ret == NOTIFY_OK) ? 1 : 0;
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}
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void profile_munmap(unsigned long addr)
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{
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blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
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}
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int task_handoff_register(struct notifier_block *n)
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{
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return atomic_notifier_chain_register(&task_free_notifier, n);
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}
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EXPORT_SYMBOL_GPL(task_handoff_register);
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int task_handoff_unregister(struct notifier_block *n)
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{
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return atomic_notifier_chain_unregister(&task_free_notifier, n);
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}
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EXPORT_SYMBOL_GPL(task_handoff_unregister);
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int profile_event_register(enum profile_type type, struct notifier_block *n)
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{
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int err = -EINVAL;
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switch (type) {
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case PROFILE_TASK_EXIT:
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err = blocking_notifier_chain_register(
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&task_exit_notifier, n);
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break;
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case PROFILE_MUNMAP:
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err = blocking_notifier_chain_register(
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&munmap_notifier, n);
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break;
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}
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return err;
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}
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EXPORT_SYMBOL_GPL(profile_event_register);
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int profile_event_unregister(enum profile_type type, struct notifier_block *n)
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{
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int err = -EINVAL;
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switch (type) {
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case PROFILE_TASK_EXIT:
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err = blocking_notifier_chain_unregister(
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&task_exit_notifier, n);
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break;
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case PROFILE_MUNMAP:
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err = blocking_notifier_chain_unregister(
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&munmap_notifier, n);
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break;
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}
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return err;
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}
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EXPORT_SYMBOL_GPL(profile_event_unregister);
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#if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
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/*
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* Each cpu has a pair of open-addressed hashtables for pending
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* profile hits. read_profile() IPI's all cpus to request them
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* to flip buffers and flushes their contents to prof_buffer itself.
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* Flip requests are serialized by the profile_flip_mutex. The sole
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* use of having a second hashtable is for avoiding cacheline
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* contention that would otherwise happen during flushes of pending
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* profile hits required for the accuracy of reported profile hits
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* and so resurrect the interrupt livelock issue.
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*
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* The open-addressed hashtables are indexed by profile buffer slot
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* and hold the number of pending hits to that profile buffer slot on
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* a cpu in an entry. When the hashtable overflows, all pending hits
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* are accounted to their corresponding profile buffer slots with
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* atomic_add() and the hashtable emptied. As numerous pending hits
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* may be accounted to a profile buffer slot in a hashtable entry,
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* this amortizes a number of atomic profile buffer increments likely
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* to be far larger than the number of entries in the hashtable,
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* particularly given that the number of distinct profile buffer
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* positions to which hits are accounted during short intervals (e.g.
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* several seconds) is usually very small. Exclusion from buffer
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* flipping is provided by interrupt disablement (note that for
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* SCHED_PROFILING or SLEEP_PROFILING profile_hit() may be called from
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* process context).
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* The hash function is meant to be lightweight as opposed to strong,
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* and was vaguely inspired by ppc64 firmware-supported inverted
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* pagetable hash functions, but uses a full hashtable full of finite
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* collision chains, not just pairs of them.
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*
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* -- nyc
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*/
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static void __profile_flip_buffers(void *unused)
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{
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int cpu = smp_processor_id();
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per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
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}
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static void profile_flip_buffers(void)
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{
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int i, j, cpu;
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mutex_lock(&profile_flip_mutex);
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j = per_cpu(cpu_profile_flip, get_cpu());
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put_cpu();
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on_each_cpu(__profile_flip_buffers, NULL, 1);
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for_each_online_cpu(cpu) {
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struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
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for (i = 0; i < NR_PROFILE_HIT; ++i) {
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if (!hits[i].hits) {
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if (hits[i].pc)
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hits[i].pc = 0;
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continue;
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}
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atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
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hits[i].hits = hits[i].pc = 0;
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}
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}
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mutex_unlock(&profile_flip_mutex);
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}
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static void profile_discard_flip_buffers(void)
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{
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int i, cpu;
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mutex_lock(&profile_flip_mutex);
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i = per_cpu(cpu_profile_flip, get_cpu());
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put_cpu();
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on_each_cpu(__profile_flip_buffers, NULL, 1);
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for_each_online_cpu(cpu) {
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struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
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memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
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}
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mutex_unlock(&profile_flip_mutex);
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}
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static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
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{
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unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
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int i, j, cpu;
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struct profile_hit *hits;
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pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
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i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
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secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
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cpu = get_cpu();
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hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
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if (!hits) {
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put_cpu();
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return;
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}
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/*
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* We buffer the global profiler buffer into a per-CPU
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* queue and thus reduce the number of global (and possibly
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* NUMA-alien) accesses. The write-queue is self-coalescing:
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*/
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local_irq_save(flags);
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do {
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for (j = 0; j < PROFILE_GRPSZ; ++j) {
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if (hits[i + j].pc == pc) {
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hits[i + j].hits += nr_hits;
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goto out;
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} else if (!hits[i + j].hits) {
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hits[i + j].pc = pc;
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hits[i + j].hits = nr_hits;
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goto out;
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}
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}
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i = (i + secondary) & (NR_PROFILE_HIT - 1);
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} while (i != primary);
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/*
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* Add the current hit(s) and flush the write-queue out
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* to the global buffer:
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*/
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atomic_add(nr_hits, &prof_buffer[pc]);
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for (i = 0; i < NR_PROFILE_HIT; ++i) {
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atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
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hits[i].pc = hits[i].hits = 0;
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}
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out:
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local_irq_restore(flags);
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put_cpu();
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}
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static int profile_dead_cpu(unsigned int cpu)
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{
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struct page *page;
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int i;
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if (prof_cpu_mask != NULL)
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cpumask_clear_cpu(cpu, prof_cpu_mask);
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for (i = 0; i < 2; i++) {
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if (per_cpu(cpu_profile_hits, cpu)[i]) {
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page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[i]);
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per_cpu(cpu_profile_hits, cpu)[i] = NULL;
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__free_page(page);
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}
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}
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return 0;
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}
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static int profile_prepare_cpu(unsigned int cpu)
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{
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int i, node = cpu_to_mem(cpu);
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struct page *page;
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per_cpu(cpu_profile_flip, cpu) = 0;
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for (i = 0; i < 2; i++) {
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if (per_cpu(cpu_profile_hits, cpu)[i])
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continue;
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page = __alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
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if (!page) {
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profile_dead_cpu(cpu);
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return -ENOMEM;
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}
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per_cpu(cpu_profile_hits, cpu)[i] = page_address(page);
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}
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return 0;
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}
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static int profile_online_cpu(unsigned int cpu)
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{
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if (prof_cpu_mask != NULL)
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cpumask_set_cpu(cpu, prof_cpu_mask);
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return 0;
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}
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#else /* !CONFIG_SMP */
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#define profile_flip_buffers() do { } while (0)
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#define profile_discard_flip_buffers() do { } while (0)
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static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
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{
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unsigned long pc;
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pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
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atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);
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}
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#endif /* !CONFIG_SMP */
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void profile_hits(int type, void *__pc, unsigned int nr_hits)
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{
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if (prof_on != type || !prof_buffer)
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return;
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do_profile_hits(type, __pc, nr_hits);
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}
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EXPORT_SYMBOL_GPL(profile_hits);
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void profile_tick(int type)
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{
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struct pt_regs *regs = get_irq_regs();
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if (!user_mode(regs) && prof_cpu_mask != NULL &&
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cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
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profile_hit(type, (void *)profile_pc(regs));
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}
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#ifdef CONFIG_PROC_FS
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <asm/uaccess.h>
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static int prof_cpu_mask_proc_show(struct seq_file *m, void *v)
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{
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seq_printf(m, "%*pb\n", cpumask_pr_args(prof_cpu_mask));
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return 0;
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}
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static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file)
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{
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return single_open(file, prof_cpu_mask_proc_show, NULL);
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}
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static ssize_t prof_cpu_mask_proc_write(struct file *file,
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const char __user *buffer, size_t count, loff_t *pos)
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{
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cpumask_var_t new_value;
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int err;
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if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
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return -ENOMEM;
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err = cpumask_parse_user(buffer, count, new_value);
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if (!err) {
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cpumask_copy(prof_cpu_mask, new_value);
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err = count;
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}
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free_cpumask_var(new_value);
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return err;
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}
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static const struct file_operations prof_cpu_mask_proc_fops = {
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.open = prof_cpu_mask_proc_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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.write = prof_cpu_mask_proc_write,
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};
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void create_prof_cpu_mask(void)
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{
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/* create /proc/irq/prof_cpu_mask */
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proc_create("irq/prof_cpu_mask", 0600, NULL, &prof_cpu_mask_proc_fops);
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}
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/*
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* This function accesses profiling information. The returned data is
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* binary: the sampling step and the actual contents of the profile
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* buffer. Use of the program readprofile is recommended in order to
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* get meaningful info out of these data.
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*/
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static ssize_t
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read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
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{
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unsigned long p = *ppos;
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ssize_t read;
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char *pnt;
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unsigned int sample_step = 1 << prof_shift;
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profile_flip_buffers();
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if (p >= (prof_len+1)*sizeof(unsigned int))
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return 0;
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if (count > (prof_len+1)*sizeof(unsigned int) - p)
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count = (prof_len+1)*sizeof(unsigned int) - p;
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read = 0;
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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,
|
|
};
|
|
|
|
int __ref create_proc_profile(void)
|
|
{
|
|
struct proc_dir_entry *entry;
|
|
#ifdef CONFIG_SMP
|
|
enum cpuhp_state online_state;
|
|
#endif
|
|
|
|
int err = 0;
|
|
|
|
if (!prof_on)
|
|
return 0;
|
|
#ifdef CONFIG_SMP
|
|
err = cpuhp_setup_state(CPUHP_PROFILE_PREPARE, "PROFILE_PREPARE",
|
|
profile_prepare_cpu, profile_dead_cpu);
|
|
if (err)
|
|
return err;
|
|
|
|
err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "AP_PROFILE_ONLINE",
|
|
profile_online_cpu, NULL);
|
|
if (err < 0)
|
|
goto err_state_prep;
|
|
online_state = err;
|
|
err = 0;
|
|
#endif
|
|
entry = proc_create("profile", S_IWUSR | S_IRUGO,
|
|
NULL, &proc_profile_operations);
|
|
if (!entry)
|
|
goto err_state_onl;
|
|
proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));
|
|
|
|
return err;
|
|
err_state_onl:
|
|
#ifdef CONFIG_SMP
|
|
cpuhp_remove_state(online_state);
|
|
err_state_prep:
|
|
cpuhp_remove_state(CPUHP_PROFILE_PREPARE);
|
|
#endif
|
|
return err;
|
|
}
|
|
subsys_initcall(create_proc_profile);
|
|
#endif /* CONFIG_PROC_FS */
|