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

   1/*
   2 * Copyright (C) 2008 ARM Limited
   3 * Copyright (C) 2014 Regents of the University of California
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License version 2 as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it will be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 */
  14
  15#include <linux/export.h>
  16#include <linux/kallsyms.h>
  17#include <linux/sched.h>
  18#include <linux/sched/debug.h>
  19#include <linux/sched/task_stack.h>
  20#include <linux/stacktrace.h>
  21#include <linux/ftrace.h>
  22
  23#ifdef CONFIG_FRAME_POINTER
  24
  25struct stackframe {
  26        unsigned long fp;
  27        unsigned long ra;
  28};
  29
  30static void notrace walk_stackframe(struct task_struct *task,
  31        struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
  32{
  33        unsigned long fp, sp, pc;
  34
  35        if (regs) {
  36                fp = GET_FP(regs);
  37                sp = GET_USP(regs);
  38                pc = GET_IP(regs);
  39        } else if (task == NULL || task == current) {
  40                const register unsigned long current_sp __asm__ ("sp");
  41                fp = (unsigned long)__builtin_frame_address(0);
  42                sp = current_sp;
  43                pc = (unsigned long)walk_stackframe;
  44        } else {
  45                /* task blocked in __switch_to */
  46                fp = task->thread.s[0];
  47                sp = task->thread.sp;
  48                pc = task->thread.ra;
  49        }
  50
  51        for (;;) {
  52                unsigned long low, high;
  53                struct stackframe *frame;
  54
  55                if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
  56                        break;
  57
  58                /* Validate frame pointer */
  59                low = sp + sizeof(struct stackframe);
  60                high = ALIGN(sp, THREAD_SIZE);
  61                if (unlikely(fp < low || fp > high || fp & 0x7))
  62                        break;
  63                /* Unwind stack frame */
  64                frame = (struct stackframe *)fp - 1;
  65                sp = fp;
  66                fp = frame->fp;
  67#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
  68                pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
  69                                           (unsigned long *)(fp - 8));
  70#else
  71                pc = frame->ra - 0x4;
  72#endif
  73        }
  74}
  75
  76#else /* !CONFIG_FRAME_POINTER */
  77
  78static void notrace walk_stackframe(struct task_struct *task,
  79        struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
  80{
  81        unsigned long sp, pc;
  82        unsigned long *ksp;
  83
  84        if (regs) {
  85                sp = GET_USP(regs);
  86                pc = GET_IP(regs);
  87        } else if (task == NULL || task == current) {
  88                const register unsigned long current_sp __asm__ ("sp");
  89                sp = current_sp;
  90                pc = (unsigned long)walk_stackframe;
  91        } else {
  92                /* task blocked in __switch_to */
  93                sp = task->thread.sp;
  94                pc = task->thread.ra;
  95        }
  96
  97        if (unlikely(sp & 0x7))
  98                return;
  99
 100        ksp = (unsigned long *)sp;
 101        while (!kstack_end(ksp)) {
 102                if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
 103                        break;
 104                pc = (*ksp++) - 0x4;
 105        }
 106}
 107
 108#endif /* CONFIG_FRAME_POINTER */
 109
 110
 111static bool print_trace_address(unsigned long pc, void *arg)
 112{
 113        print_ip_sym(pc);
 114        return false;
 115}
 116
 117void show_stack(struct task_struct *task, unsigned long *sp)
 118{
 119        pr_cont("Call Trace:\n");
 120        walk_stackframe(task, NULL, print_trace_address, NULL);
 121}
 122
 123
 124static bool save_wchan(unsigned long pc, void *arg)
 125{
 126        if (!in_sched_functions(pc)) {
 127                unsigned long *p = arg;
 128                *p = pc;
 129                return true;
 130        }
 131        return false;
 132}
 133
 134unsigned long get_wchan(struct task_struct *task)
 135{
 136        unsigned long pc = 0;
 137
 138        if (likely(task && task != current && task->state != TASK_RUNNING))
 139                walk_stackframe(task, NULL, save_wchan, &pc);
 140        return pc;
 141}
 142
 143
 144#ifdef CONFIG_STACKTRACE
 145
 146static bool __save_trace(unsigned long pc, void *arg, bool nosched)
 147{
 148        struct stack_trace *trace = arg;
 149
 150        if (unlikely(nosched && in_sched_functions(pc)))
 151                return false;
 152        if (unlikely(trace->skip > 0)) {
 153                trace->skip--;
 154                return false;
 155        }
 156
 157        trace->entries[trace->nr_entries++] = pc;
 158        return (trace->nr_entries >= trace->max_entries);
 159}
 160
 161static bool save_trace(unsigned long pc, void *arg)
 162{
 163        return __save_trace(pc, arg, false);
 164}
 165
 166/*
 167 * Save stack-backtrace addresses into a stack_trace buffer.
 168 */
 169void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 170{
 171        walk_stackframe(tsk, NULL, save_trace, trace);
 172        if (trace->nr_entries < trace->max_entries)
 173                trace->entries[trace->nr_entries++] = ULONG_MAX;
 174}
 175EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
 176
 177void save_stack_trace(struct stack_trace *trace)
 178{
 179        save_stack_trace_tsk(NULL, trace);
 180}
 181EXPORT_SYMBOL_GPL(save_stack_trace);
 182
 183#endif /* CONFIG_STACKTRACE */
 184