forked from Minki/linux
perf_counter: x86: callchain support
Provide the x86 perf_callchain() implementation. Code based on the ftrace/sysprof code from Soeren Sandmann Pedersen. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Paul Mackerras <paulus@samba.org> Cc: Soeren Sandmann Pedersen <sandmann@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <srostedt@redhat.com> Orig-LKML-Reference: <20090330171024.341993293@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -16,8 +16,10 @@
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#include <linux/module.h>
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#include <linux/module.h>
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#include <linux/kdebug.h>
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#include <linux/kdebug.h>
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#include <linux/sched.h>
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#include <linux/sched.h>
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#include <linux/uaccess.h>
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#include <asm/apic.h>
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#include <asm/apic.h>
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#include <asm/stacktrace.h>
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static bool perf_counters_initialized __read_mostly;
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static bool perf_counters_initialized __read_mostly;
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@ -958,3 +960,155 @@ hw_perf_counter_init(struct perf_counter *counter)
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return &x86_perf_counter_ops;
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return &x86_perf_counter_ops;
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}
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}
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/*
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* callchain support
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*/
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static inline
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void callchain_store(struct perf_callchain_entry *entry, unsigned long ip)
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{
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if (entry->nr < MAX_STACK_DEPTH)
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entry->ip[entry->nr++] = ip;
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}
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static DEFINE_PER_CPU(struct perf_callchain_entry, irq_entry);
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static DEFINE_PER_CPU(struct perf_callchain_entry, nmi_entry);
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static void
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backtrace_warning_symbol(void *data, char *msg, unsigned long symbol)
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{
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/* Ignore warnings */
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}
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static void backtrace_warning(void *data, char *msg)
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{
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/* Ignore warnings */
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}
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static int backtrace_stack(void *data, char *name)
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{
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/* Don't bother with IRQ stacks for now */
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return -1;
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}
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static void backtrace_address(void *data, unsigned long addr, int reliable)
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{
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struct perf_callchain_entry *entry = data;
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if (reliable)
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callchain_store(entry, addr);
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}
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static const struct stacktrace_ops backtrace_ops = {
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.warning = backtrace_warning,
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.warning_symbol = backtrace_warning_symbol,
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.stack = backtrace_stack,
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.address = backtrace_address,
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};
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static void
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perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
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{
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unsigned long bp;
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char *stack;
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callchain_store(entry, instruction_pointer(regs));
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stack = ((char *)regs + sizeof(struct pt_regs));
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#ifdef CONFIG_FRAME_POINTER
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bp = frame_pointer(regs);
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#else
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bp = 0;
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#endif
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dump_trace(NULL, regs, (void *)stack, bp, &backtrace_ops, entry);
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}
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struct stack_frame {
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const void __user *next_fp;
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unsigned long return_address;
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};
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static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
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{
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int ret;
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if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
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return 0;
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ret = 1;
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pagefault_disable();
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if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
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ret = 0;
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pagefault_enable();
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return ret;
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}
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static void
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perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry)
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{
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struct stack_frame frame;
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const void __user *fp;
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regs = (struct pt_regs *)current->thread.sp0 - 1;
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fp = (void __user *)regs->bp;
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callchain_store(entry, regs->ip);
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while (entry->nr < MAX_STACK_DEPTH) {
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frame.next_fp = NULL;
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frame.return_address = 0;
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if (!copy_stack_frame(fp, &frame))
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break;
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if ((unsigned long)fp < user_stack_pointer(regs))
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break;
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callchain_store(entry, frame.return_address);
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fp = frame.next_fp;
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}
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}
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static void
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perf_do_callchain(struct pt_regs *regs, struct perf_callchain_entry *entry)
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{
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int is_user;
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if (!regs)
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return;
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is_user = user_mode(regs);
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if (!current || current->pid == 0)
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return;
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if (is_user && current->state != TASK_RUNNING)
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return;
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if (!is_user)
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perf_callchain_kernel(regs, entry);
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if (current->mm)
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perf_callchain_user(regs, entry);
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}
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struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
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{
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struct perf_callchain_entry *entry;
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if (in_nmi())
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entry = &__get_cpu_var(nmi_entry);
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else
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entry = &__get_cpu_var(irq_entry);
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entry->nr = 0;
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perf_do_callchain(regs, entry);
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return entry;
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}
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