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
  18 static void callchain_warning(void *data, char *msg)
  19 {
  20 }
  21
  22 static void
  23 callchain_warning_symbol(void *data, char *msg, unsigned long symbol)
  24 {
  25 }
  26
  27 static int callchain_stack(void *data, char *name)
  28 {
  29         return 0;
  30 }
  31
  32 static void callchain_address(void *data, unsigned long addr, int reliable)
  33 {
  34         struct perf_callchain_entry *entry = data;
  35
  36         if (reliable)
  37                 perf_callchain_store(entry, addr);
  38 }
  39
  40 static const struct stacktrace_ops callchain_ops = {
  41         .warning        = callchain_warning,
  42         .warning_symbol = callchain_warning_symbol,
  43         .stack          = callchain_stack,
  44         .address        = callchain_address,
  45 };
  46
  47 static void
  48 perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
  49 {
  50         perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
  51         perf_callchain_store(entry, regs->pc);
  52
  53         unwind_stack(NULL, regs, NULL, &callchain_ops, entry);
  54 }
  55
  56 static void
  57 perf_do_callchain(struct pt_regs *regs, struct perf_callchain_entry *entry)
  58 {
  59         int is_user;
  60
  61         if (!regs)
  62                 return;
  63
  64         is_user = user_mode(regs);
  65
  66         /*
  67          * Only the kernel side is implemented for now.
  68          */
  69         if (!is_user)
  70                 perf_callchain_kernel(regs, entry);
  71 }
  72
  73 /*
  74  * No need for separate IRQ and NMI entries.
  75  */
  76 static DEFINE_PER_CPU(struct perf_callchain_entry, callchain);
  77
  78 struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
  79 {
  80         struct perf_callchain_entry *entry = &__get_cpu_var(callchain);
  81
  82         entry->nr = 0;
  83
  84         perf_do_callchain(regs, entry);
  85
  86         return entry;
  87 }