1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Stack trace management functions
4 *
5 * Copyright IBM Corp. 2006
6 */
7
8#include <linux/stacktrace.h>
9#include <linux/uaccess.h>
10#include <linux/compat.h>
11#include <asm/stacktrace.h>
12#include <asm/unwind.h>
13#include <asm/kprobes.h>
14#include <asm/ptrace.h>
15
16void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
17 struct task_struct *task, struct pt_regs *regs)
18{
19 struct unwind_state state;
20 unsigned long addr;
21
22 unwind_for_each_frame(&state, task, regs, 0) {
23 addr = unwind_get_return_address(state: &state);
24 if (!addr || !consume_entry(cookie, addr))
25 break;
26 }
27}
28
29int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
30 void *cookie, struct task_struct *task)
31{
32 struct unwind_state state;
33 unsigned long addr;
34
35 unwind_for_each_frame(&state, task, NULL, 0) {
36 if (state.stack_info.type != STACK_TYPE_TASK)
37 return -EINVAL;
38
39 if (state.regs)
40 return -EINVAL;
41
42 addr = unwind_get_return_address(state: &state);
43 if (!addr)
44 return -EINVAL;
45
46#ifdef CONFIG_RETHOOK
47 /*
48 * Mark stacktraces with krethook functions on them
49 * as unreliable.
50 */
51 if (state.ip == (unsigned long)arch_rethook_trampoline)
52 return -EINVAL;
53#endif
54
55 if (!consume_entry(cookie, addr))
56 return -EINVAL;
57 }
58
59 /* Check for stack corruption */
60 if (unwind_error(state: &state))
61 return -EINVAL;
62 return 0;
63}
64
65void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
66 const struct pt_regs *regs)
67{
68 struct stack_frame_user __user *sf;
69 unsigned long ip, sp;
70 bool first = true;
71
72 if (is_compat_task())
73 return;
74 if (!consume_entry(cookie, instruction_pointer(regs)))
75 return;
76 sf = (void __user *)user_stack_pointer(regs);
77 pagefault_disable();
78 while (1) {
79 if (__get_user(sp, &sf->back_chain))
80 break;
81 if (__get_user(ip, &sf->gprs[8]))
82 break;
83 if (ip & 0x1) {
84 /*
85 * If the instruction address is invalid, and this
86 * is the first stack frame, assume r14 has not
87 * been written to the stack yet. Otherwise exit.
88 */
89 if (first && !(regs->gprs[14] & 0x1))
90 ip = regs->gprs[14];
91 else
92 break;
93 }
94 if (!consume_entry(cookie, ip))
95 break;
96 /* Sanity check: ABI requires SP to be aligned 8 bytes. */
97 if (!sp || sp & 0x7)
98 break;
99 sf = (void __user *)sp;
100 first = false;
101 }
102 pagefault_enable();
103}
104

source code of linux/arch/s390/kernel/stacktrace.c