arch/mips/kernel/perf_event.c

   1 /*
   2  * Linux performance counter support for MIPS.
   3  *
   4  * Copyright (C) 2010 MIPS Technologies, Inc.
   5  * Author: Deng-Cheng Zhu
   6  *
   7  * This code is based on the implementation for ARM, which is in turn
   8  * based on the sparc64 perf event code and the x86 code. Performance
   9  * counter access is based on the MIPS Oprofile code. And the callchain
  10  * support references the code of MIPS stacktrace.c.
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License version 2 as
  14  * published by the Free Software Foundation.
  15  */
  16
  17 #include <linux/perf_event.h>
  18
  19 #include <asm/stacktrace.h>
  20
  21 /* Callchain handling code. */
  22
  23 /*
  24  * Leave userspace callchain empty for now. When we find a way to trace
  25  * the user stack callchains, we will add it here.
  26  */
  27
  28 static void save_raw_perf_callchain(struct perf_callchain_entry *entry,
  29         unsigned long reg29)
  30 {
  31         unsigned long *sp = (unsigned long *)reg29;
  32         unsigned long addr;
  33
  34         while (!kstack_end(sp)) {
  35                 addr = *sp++;
  36                 if (__kernel_text_address(addr)) {
  37                         perf_callchain_store(entry, addr);
  38                         if (entry->nr >= PERF_MAX_STACK_DEPTH)
  39                                 break;
  40                 }
  41         }
  42 }
  43
  44 void perf_callchain_kernel(struct perf_callchain_entry *entry,
  45                       struct pt_regs *regs)
  46 {
  47         unsigned long sp = regs->regs[29];
  48 #ifdef CONFIG_KALLSYMS
  49         unsigned long ra = regs->regs[31];
  50         unsigned long pc = regs->cp0_epc;
  51
  52         if (raw_show_trace || !__kernel_text_address(pc)) {
  53                 unsigned long stack_page =
  54                         (unsigned long)task_stack_page(current);
  55                 if (stack_page && sp >= stack_page &&
  56                     sp <= stack_page + THREAD_SIZE - 32)
  57                         save_raw_perf_callchain(entry, sp);
  58                 return;
  59         }
  60         do {
  61                 perf_callchain_store(entry, pc);
  62                 if (entry->nr >= PERF_MAX_STACK_DEPTH)
  63                         break;
  64                 pc = unwind_stack(current, &sp, pc, &ra);
  65         } while (pc);
  66 #else
  67         save_raw_perf_callchain(entry, sp);
  68 #endif
  69 }