LXR linux/arch/mips/kernel/stacktrace.c

   1/*
   2 * Stack trace management functions
   3 *
   4 *  Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   5 */
   6#include <linux/sched.h>
   7#include <linux/sched/debug.h>
   8#include <linux/sched/task_stack.h>
   9#include <linux/stacktrace.h>
  10#include <linux/export.h>
  11#include <asm/stacktrace.h>
  12
  13/*
  14 * Save stack-backtrace addresses into a stack_trace buffer:
  15 */
  16static void save_raw_context_stack(struct stack_trace *trace,
  17        unsigned long reg29, int savesched)
  18{
  19        unsigned long *sp = (unsigned long *)reg29;
  20        unsigned long addr;
  21
  22        while (!kstack_end(sp)) {
  23                addr = *sp++;
  24                if (__kernel_text_address(addr) &&
  25                    (savesched || !in_sched_functions(addr))) {
  26                        if (trace->skip > 0)
  27                                trace->skip--;
  28                        else
  29                                trace->entries[trace->nr_entries++] = addr;
  30                        if (trace->nr_entries >= trace->max_entries)
  31                                break;
  32                }
  33        }
  34}
  35
  36static void save_context_stack(struct stack_trace *trace,
  37        struct task_struct *tsk, struct pt_regs *regs, int savesched)
  38{
  39        unsigned long sp = regs->regs[29];
  40#ifdef CONFIG_KALLSYMS
  41        unsigned long ra = regs->regs[31];
  42        unsigned long pc = regs->cp0_epc;
  43
  44        if (raw_show_trace || !__kernel_text_address(pc)) {
  45                unsigned long stack_page =
  46                        (unsigned long)task_stack_page(tsk);
  47                if (stack_page && sp >= stack_page &&
  48                    sp <= stack_page + THREAD_SIZE - 32)
  49                        save_raw_context_stack(trace, sp, savesched);
  50                return;
  51        }
  52        do {
  53                if (savesched || !in_sched_functions(pc)) {
  54                        if (trace->skip > 0)
  55                                trace->skip--;
  56                        else
  57                                trace->entries[trace->nr_entries++] = pc;
  58                        if (trace->nr_entries >= trace->max_entries)
  59                                break;
  60                }
  61                pc = unwind_stack(tsk, &sp, pc, &ra);
  62        } while (pc);
  63#else
  64        save_raw_context_stack(trace, sp, savesched);
  65#endif
  66}
  67
  68/*
  69 * Save stack-backtrace addresses into a stack_trace buffer.
  70 */
  71void save_stack_trace(struct stack_trace *trace)
  72{
  73        save_stack_trace_tsk(current, trace);
  74}
  75EXPORT_SYMBOL_GPL(save_stack_trace);
  76
  77void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  78{
  79        struct pt_regs dummyregs;
  80        struct pt_regs *regs = &dummyregs;
  81
  82        WARN_ON(trace->nr_entries || !trace->max_entries);
  83
  84        if (tsk != current) {
  85                regs->regs[29] = tsk->thread.reg29;
  86                regs->regs[31] = 0;
  87                regs->cp0_epc = tsk->thread.reg31;
  88        } else
  89                prepare_frametrace(regs);
  90        save_context_stack(trace, tsk, regs, tsk == current);
  91}
  92EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
  93