LXR linux/arch/mips/kernel/perf

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Linux performance counter support for MIPS.
   4 *
   5 * Copyright (C) 2010 MIPS Technologies, Inc.
   6 * Author: Deng-Cheng Zhu
   7 *
   8 * This code is based on the implementation for ARM, which is in turn
   9 * based on the sparc64 perf event code and the x86 code. Performance
  10 * counter access is based on the MIPS Oprofile code. And the callchain
  11 * support references the code of MIPS stacktrace.c.
  12 */
  13
  14#include <linux/perf_event.h>
  15#include <linux/sched/task_stack.h>
  16
  17#include <asm/stacktrace.h>
  18
  19/* Callchain handling code. */
  20
  21/*
  22 * Leave userspace callchain empty for now. When we find a way to trace
  23 * the user stack callchains, we will add it here.
  24 */
  25
  26static void save_raw_perf_callchain(struct perf_callchain_entry_ctx *entry,
  27                                    unsigned long reg29)
  28{
  29        unsigned long *sp = (unsigned long *)reg29;
  30        unsigned long addr;
  31
  32        while (!kstack_end(sp)) {
  33                addr = *sp++;
  34                if (__kernel_text_address(addr)) {
  35                        perf_callchain_store(entry, addr);
  36                        if (entry->nr >= entry->max_stack)
  37                                break;
  38                }
  39        }
  40}
  41
  42void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
  43                           struct pt_regs *regs)
  44{
  45        unsigned long sp = regs->regs[29];
  46#ifdef CONFIG_KALLSYMS
  47        unsigned long ra = regs->regs[31];
  48        unsigned long pc = regs->cp0_epc;
  49
  50        if (raw_show_trace || !__kernel_text_address(pc)) {
  51                unsigned long stack_page =
  52                        (unsigned long)task_stack_page(current);
  53                if (stack_page && sp >= stack_page &&
  54                    sp <= stack_page + THREAD_SIZE - 32)
  55                        save_raw_perf_callchain(entry, sp);
  56                return;
  57        }
  58        do {
  59                perf_callchain_store(entry, pc);
  60                if (entry->nr >= entry->max_stack)
  61                        break;
  62                pc = unwind_stack(current, &sp, pc, &ra);
  63        } while (pc);
  64#else
  65        save_raw_perf_callchain(entry, sp);
  66#endif
  67}
  68