1 /* 2 * arch/mips/kernel/stacktrace.c 3 * 4 * Stack trace management functions 5 * 6 * Copyright (C) 2006 Atsushi Nemoto <[email protected]> 7 */ 8 #include <linux/sched.h> 9 #include <linux/stacktrace.h> 10 #include <asm/stacktrace.h> 11 12 /* 13 * Save stack-backtrace addresses into a stack_trace buffer: 14 */ 15 static void save_raw_context_stack(struct stack_trace *trace, 16 unsigned long reg29) 17 { 18 unsigned long *sp = (unsigned long *)reg29; 19 unsigned long addr; 20 21 while (!kstack_end(sp)) { 22 addr = *sp++; 23 if (__kernel_text_address(addr)) { 24 if (trace->skip > 0) 25 trace->skip--; 26 else 27 trace->entries[trace->nr_entries++] = addr; 28 if (trace->nr_entries >= trace->max_entries) 29 break; 30 } 31 } 32 } 33 34 static struct pt_regs * save_context_stack(struct stack_trace *trace, 35 struct task_struct *task, struct pt_regs *regs) 36 { 37 unsigned long sp = regs->regs[29]; 38 #ifdef CONFIG_KALLSYMS 39 unsigned long ra = regs->regs[31]; 40 unsigned long pc = regs->cp0_epc; 41 unsigned long stack_page = 42 (unsigned long)task_stack_page(task); 43 extern void ret_from_irq(void); 44 extern void ret_from_exception(void); 45 46 if (raw_show_trace || !__kernel_text_address(pc)) { 47 if (stack_page && sp >= stack_page && 48 sp <= stack_page + THREAD_SIZE - 32) 49 save_raw_context_stack(trace, sp); 50 return NULL; 51 } 52 do { 53 if (trace->skip > 0) 54 trace->skip--; 55 else 56 trace->entries[trace->nr_entries++] = pc; 57 if (trace->nr_entries >= trace->max_entries) 58 break; 59 /* 60 * If we reached the bottom of interrupt context, 61 * return saved pt_regs. 62 */ 63 if (pc == (unsigned long)ret_from_irq || 64 pc == (unsigned long)ret_from_exception) { 65 if (stack_page && sp >= stack_page && 66 sp <= stack_page + THREAD_SIZE - 32) 67 return (struct pt_regs *)sp; 68 break; 69 } 70 pc = unwind_stack(task, &sp, pc, ra); 71 ra = 0; 72 } while (pc); 73 #else 74 save_raw_context_stack(sp); 75 #endif 76 77 return NULL; 78 } 79 80 /* 81 * Save stack-backtrace addresses into a stack_trace buffer. 82 */ 83 void save_stack_trace(struct stack_trace *trace, struct task_struct *task) 84 { 85 struct pt_regs dummyregs; 86 struct pt_regs *regs = &dummyregs; 87 88 WARN_ON(trace->nr_entries || !trace->max_entries); 89 90 if (task && task != current) { 91 regs->regs[29] = task->thread.reg29; 92 regs->regs[31] = 0; 93 regs->cp0_epc = task->thread.reg31; 94 } else { 95 if (!task) 96 task = current; 97 prepare_frametrace(regs); 98 } 99 100 while (1) { 101 regs = save_context_stack(trace, task, regs); 102 if (!regs || trace->nr_entries >= trace->max_entries) 103 break; 104 } 105 } 106