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 } 71