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 #include <linux/sched/task_stack.h>
  19
  20 #include <asm/stacktrace.h>
  21
  22 /* Callchain handling code. */
  23
  24 /*
  25  * Leave userspace callchain empty for now. When we find a way to trace
  26  * the user stack callchains, we will add it here.
  27  */
  28
  29 static void save_raw_perf_callchain(struct perf_callchain_entry_ctx *entry,
  30                                     unsigned long reg29)
  31 {
  32         unsigned long *sp = (unsigned long *)reg29;
  33         unsigned long addr;
  34
  35         while (!kstack_end(sp)) {
  36                 addr = *sp++;
  37                 if (__kernel_text_address(addr)) {
  38                         perf_callchain_store(entry, addr);
  39                         if (entry->nr >= entry->max_stack)
  40                                 break;
  41                 }
  42         }
  43 }
  44
  45 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
  46                            struct pt_regs *regs)
  47 {
  48         unsigned long sp = regs->regs[29];
  49 #ifdef CONFIG_KALLSYMS
  50         unsigned long ra = regs->regs[31];
  51         unsigned long pc = regs->cp0_epc;
  52
  53         if (raw_show_trace || !__kernel_text_address(pc)) {
  54                 unsigned long stack_page =
  55                         (unsigned long)task_stack_page(current);
  56                 if (stack_page && sp >= stack_page &&
  57                     sp <= stack_page + THREAD_SIZE - 32)
  58                         save_raw_perf_callchain(entry, sp);
  59                 return;
  60         }
  61         do {
  62                 perf_callchain_store(entry, pc);
  63                 if (entry->nr >= entry->max_stack)
  64                         break;
  65                 pc = unwind_stack(current, &sp, pc, &ra);
  66         } while (pc);
  67 #else
  68         save_raw_perf_callchain(entry, sp);
  69 #endif
  70 }