LXR linux/arch/mips/kernel/perf

   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
  29static 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
  45void 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}
  71