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);
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);
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))
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