1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Stack trace management functions
4 *
5 * Copyright IBM Corp. 2006
6 */
7
8#include <linux/perf_event.h>
9#include <linux/stacktrace.h>
10#include <linux/uaccess.h>
11#include <asm/asm-offsets.h>
12#include <asm/stacktrace.h>
13#include <asm/unwind.h>
14#include <asm/kprobes.h>
15#include <asm/ptrace.h>
16
17void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
18 struct task_struct *task, struct pt_regs *regs)
19{
20 struct unwind_state state;
21 unsigned long addr;
22
23 unwind_for_each_frame(&state, task, regs, 0) {
24 addr = unwind_get_return_address(state: &state);
25 if (!addr || !consume_entry(cookie, addr))
26 break;
27 }
28}
29
30int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
31 void *cookie, struct task_struct *task)
32{
33 struct unwind_state state;
34 unsigned long addr;
35
36 unwind_for_each_frame(&state, task, NULL, 0) {
37 if (state.stack_info.type != STACK_TYPE_TASK)
38 return -EINVAL;
39
40 if (state.regs)
41 return -EINVAL;
42
43 addr = unwind_get_return_address(state: &state);
44 if (!addr)
45 return -EINVAL;
46
47#ifdef CONFIG_RETHOOK
48 /*
49 * Mark stacktraces with krethook functions on them
50 * as unreliable.
51 */
52 if (state.ip == (unsigned long)arch_rethook_trampoline)
53 return -EINVAL;
54#endif
55
56 if (!consume_entry(cookie, addr))
57 return -EINVAL;
58 }
59
60 /* Check for stack corruption */
61 if (unwind_error(state: &state))
62 return -EINVAL;
63 return 0;
64}
65
66static inline bool store_ip(stack_trace_consume_fn consume_entry, void *cookie,
67 struct perf_callchain_entry_ctx *entry, bool perf,
68 unsigned long ip)
69{
70#ifdef CONFIG_PERF_EVENTS
71 if (perf) {
72 if (perf_callchain_store(ctx: entry, ip))
73 return false;
74 return true;
75 }
76#endif
77 return consume_entry(cookie, ip);
78}
79
80static inline bool ip_invalid(unsigned long ip)
81{
82 /*
83 * Perform some basic checks if an instruction address taken
84 * from unreliable source is invalid.
85 */
86 if (ip & 1)
87 return true;
88 if (ip < mmap_min_addr)
89 return true;
90 if (ip >= current->mm->context.asce_limit)
91 return true;
92 return false;
93}
94
95static inline bool ip_within_vdso(unsigned long ip)
96{
97 return in_range(ip, current->mm->context.vdso_base, vdso_text_size());
98}
99
100void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *cookie,
101 struct perf_callchain_entry_ctx *entry,
102 const struct pt_regs *regs, bool perf)
103{
104 struct stack_frame_vdso_wrapper __user *sf_vdso;
105 struct stack_frame_user __user *sf;
106 unsigned long ip, sp;
107
108 if (!current->mm)
109 return;
110 ip = instruction_pointer(regs);
111 if (!store_ip(consume_entry, cookie, entry, perf, ip))
112 return;
113 sf = (void __user *)user_stack_pointer(regs);
114 pagefault_disable();
115 while (1) {
116 if (__get_user(sp, &sf->back_chain))
117 break;
118 /*
119 * VDSO entry code has a non-standard stack frame layout.
120 * See VDSO user wrapper code for details.
121 */
122 if (!sp && ip_within_vdso(ip)) {
123 sf_vdso = (void __user *)sf;
124 if (__get_user(ip, &sf_vdso->return_address))
125 break;
126 sp = (unsigned long)sf + STACK_FRAME_VDSO_OVERHEAD;
127 sf = (void __user *)sp;
128 if (__get_user(sp, &sf->back_chain))
129 break;
130 } else {
131 sf = (void __user *)sp;
132 if (__get_user(ip, &sf->gprs[8]))
133 break;
134 }
135 /* Validate SP and RA (ABI requires SP to be 8 byte aligned). */
136 if (sp & 0x7 || ip_invalid(ip))
137 break;
138 if (!store_ip(consume_entry, cookie, entry, perf, ip))
139 break;
140 }
141 pagefault_enable();
142}
143
144void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
145 const struct pt_regs *regs)
146{
147 arch_stack_walk_user_common(consume_entry, cookie, NULL, regs, perf: false);
148}
149

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