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 26 static 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 42 void 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