arch/sh/kernel/perf_callchain.c

   1 /*
   2  * Performance event callchain support - SuperH architecture code
   3  *
   4  * Copyright (C) 2009  Paul Mundt
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  */
  10 #include <linux/kernel.h>
  11 #include <linux/sched.h>
  12 #include <linux/perf_event.h>
  13 #include <linux/percpu.h>
  14 #include <asm/unwinder.h>
  15 #include <asm/ptrace.h>
  16
  17 static inline void callchain_store(struct perf_callchain_entry *entry, u64 ip)
  18 {
  19         if (entry->nr < PERF_MAX_STACK_DEPTH)
  20                 entry->ip[entry->nr++] = ip;
  21 }
  22
  23 static void callchain_warning(void *data, char *msg)
  24 {
  25 }
  26
  27 static void
  28 callchain_warning_symbol(void *data, char *msg, unsigned long symbol)
  29 {
  30 }
  31
  32 static int callchain_stack(void *data, char *name)
  33 {
  34         return 0;
  35 }
  36
  37 static void callchain_address(void *data, unsigned long addr, int reliable)
  38 {
  39         struct perf_callchain_entry *entry = data;
  40
  41         if (reliable)
  42                 callchain_store(entry, addr);
  43 }
  44
  45 static const struct stacktrace_ops callchain_ops = {
  46         .warning        = callchain_warning,
  47         .warning_symbol = callchain_warning_symbol,
  48         .stack          = callchain_stack,
  49         .address        = callchain_address,
  50 };
  51
  52 static void
  53 perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
  54 {
  55         callchain_store(entry, PERF_CONTEXT_KERNEL);
  56         callchain_store(entry, regs->pc);
  57
  58         unwind_stack(NULL, regs, NULL, &callchain_ops, entry);
  59 }
  60
  61 static void
  62 perf_do_callchain(struct pt_regs *regs, struct perf_callchain_entry *entry)
  63 {
  64         int is_user;
  65
  66         if (!regs)
  67                 return;
  68
  69         is_user = user_mode(regs);
  70
  71         if (!current || current->pid == 0)
  72                 return;
  73
  74         if (is_user && current->state != TASK_RUNNING)
  75                 return;
  76
  77         /*
  78          * Only the kernel side is implemented for now.
  79          */
  80         if (!is_user)
  81                 perf_callchain_kernel(regs, entry);
  82 }
  83
  84 /*
  85  * No need for separate IRQ and NMI entries.
  86  */
  87 static DEFINE_PER_CPU(struct perf_callchain_entry, callchain);
  88
  89 struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
  90 {
  91         struct perf_callchain_entry *entry = &__get_cpu_var(callchain);
  92
  93         entry->nr = 0;
  94
  95         perf_do_callchain(regs, entry);
  96
  97         return entry;
  98 }