1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Stack trace management functions
4 *
5 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
6 */
7#include <linux/sched.h>
8#include <linux/sched/debug.h>
9#include <linux/sched/task_stack.h>
10#include <linux/stacktrace.h>
11#include <linux/export.h>
12#include <asm/stacktrace.h>
13
14/*
15 * Save stack-backtrace addresses into a stack_trace buffer:
16 */
17static void save_raw_context_stack(struct stack_trace *trace,
18 unsigned long reg29, int savesched)
19{
20 unsigned long *sp = (unsigned long *)reg29;
21 unsigned long addr;
22
23 while (!kstack_end(addr: sp)) {
24 addr = *sp++;
25 if (__kernel_text_address(addr) &&
26 (savesched || !in_sched_functions(addr))) {
27 if (trace->skip > 0)
28 trace->skip--;
29 else
30 trace->entries[trace->nr_entries++] = addr;
31 if (trace->nr_entries >= trace->max_entries)
32 break;
33 }
34 }
35}
36
37static void save_context_stack(struct stack_trace *trace,
38 struct task_struct *tsk, struct pt_regs *regs, int savesched)
39{
40 unsigned long sp = regs->regs[29];
41#ifdef CONFIG_KALLSYMS
42 unsigned long ra = regs->regs[31];
43 unsigned long pc = regs->cp0_epc;
44
45 if (raw_show_trace || !__kernel_text_address(addr: pc)) {
46 unsigned long stack_page =
47 (unsigned long)task_stack_page(task: tsk);
48 if (stack_page && sp >= stack_page &&
49 sp <= stack_page + THREAD_SIZE - 32)
50 save_raw_context_stack(trace, reg29: sp, savesched);
51 return;
52 }
53 do {
54 if (savesched || !in_sched_functions(addr: pc)) {
55 if (trace->skip > 0)
56 trace->skip--;
57 else
58 trace->entries[trace->nr_entries++] = pc;
59 if (trace->nr_entries >= trace->max_entries)
60 break;
61 }
62 pc = unwind_stack(tsk, &sp, pc, &ra);
63 } while (pc);
64#else
65 save_raw_context_stack(trace, sp, savesched);
66#endif
67}
68
69/*
70 * Save stack-backtrace addresses into a stack_trace buffer.
71 */
72void save_stack_trace(struct stack_trace *trace)
73{
74 save_stack_trace_tsk(current, trace);
75}
76EXPORT_SYMBOL_GPL(save_stack_trace);
77
78void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
79{
80 struct pt_regs dummyregs;
81 struct pt_regs *regs = &dummyregs;
82
83 WARN_ON(trace->nr_entries || !trace->max_entries);
84
85 if (tsk != current) {
86 regs->regs[29] = tsk->thread.reg29;
87 regs->regs[31] = 0;
88 regs->cp0_epc = tsk->thread.reg31;
89 } else
90 prepare_frametrace(regs);
91 save_context_stack(trace, tsk, regs, savesched: tsk == current);
92}
93EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
94

source code of linux/arch/mips/kernel/stacktrace.c