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 | */ |
17 | static 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 | |
37 | static 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 | */ |
72 | void save_stack_trace(struct stack_trace *trace) |
73 | { |
74 | save_stack_trace_tsk(current, trace); |
75 | } |
76 | EXPORT_SYMBOL_GPL(save_stack_trace); |
77 | |
78 | void 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 | } |
93 | EXPORT_SYMBOL_GPL(save_stack_trace_tsk); |
94 | |