1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
5 */
6 #include <linux/sched/debug.h>
7 #include <linux/kallsyms.h>
8 #include <linux/kprobes.h>
9 #include <linux/uaccess.h>
10 #include <linux/hardirq.h>
11 #include <linux/kdebug.h>
12 #include <linux/export.h>
13 #include <linux/ptrace.h>
14 #include <linux/kexec.h>
15 #include <linux/sysfs.h>
16 #include <linux/bug.h>
17 #include <linux/nmi.h>
18
19 #include <asm/stacktrace.h>
20
21 static char *exception_stack_names[N_EXCEPTION_STACKS] = {
22 [ DOUBLEFAULT_STACK-1 ] = "#DF",
23 [ NMI_STACK-1 ] = "NMI",
24 [ DEBUG_STACK-1 ] = "#DB",
25 [ MCE_STACK-1 ] = "#MC",
26 };
27
28 static unsigned long exception_stack_sizes[N_EXCEPTION_STACKS] = {
29 [0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STKSZ,
30 [DEBUG_STACK - 1] = DEBUG_STKSZ
31 };
32
stack_type_name(enum stack_type type)33 const char *stack_type_name(enum stack_type type)
34 {
35 BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
36
37 if (type == STACK_TYPE_IRQ)
38 return "IRQ";
39
40 if (type == STACK_TYPE_ENTRY) {
41 /*
42 * On 64-bit, we have a generic entry stack that we
43 * use for all the kernel entry points, including
44 * SYSENTER.
45 */
46 return "ENTRY_TRAMPOLINE";
47 }
48
49 if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
50 return exception_stack_names[type - STACK_TYPE_EXCEPTION];
51
52 return NULL;
53 }
54
in_exception_stack(unsigned long * stack,struct stack_info * info)55 static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
56 {
57 unsigned long *begin, *end;
58 struct pt_regs *regs;
59 unsigned k;
60
61 BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
62
63 for (k = 0; k < N_EXCEPTION_STACKS; k++) {
64 end = (unsigned long *)raw_cpu_ptr(&orig_ist)->ist[k];
65 begin = end - (exception_stack_sizes[k] / sizeof(long));
66 regs = (struct pt_regs *)end - 1;
67
68 if (stack <= begin || stack >= end)
69 continue;
70
71 info->type = STACK_TYPE_EXCEPTION + k;
72 info->begin = begin;
73 info->end = end;
74 info->next_sp = (unsigned long *)regs->sp;
75
76 return true;
77 }
78
79 return false;
80 }
81
in_irq_stack(unsigned long * stack,struct stack_info * info)82 static bool in_irq_stack(unsigned long *stack, struct stack_info *info)
83 {
84 unsigned long *end = (unsigned long *)this_cpu_read(irq_stack_ptr);
85 unsigned long *begin = end - (IRQ_STACK_SIZE / sizeof(long));
86
87 /*
88 * This is a software stack, so 'end' can be a valid stack pointer.
89 * It just means the stack is empty.
90 */
91 if (stack <= begin || stack > end)
92 return false;
93
94 info->type = STACK_TYPE_IRQ;
95 info->begin = begin;
96 info->end = end;
97
98 /*
99 * The next stack pointer is the first thing pushed by the entry code
100 * after switching to the irq stack.
101 */
102 info->next_sp = (unsigned long *)*(end - 1);
103
104 return true;
105 }
106
get_stack_info(unsigned long * stack,struct task_struct * task,struct stack_info * info,unsigned long * visit_mask)107 int get_stack_info(unsigned long *stack, struct task_struct *task,
108 struct stack_info *info, unsigned long *visit_mask)
109 {
110 if (!stack)
111 goto unknown;
112
113 task = task ? : current;
114
115 if (in_task_stack(stack, task, info))
116 goto recursion_check;
117
118 if (task != current)
119 goto unknown;
120
121 if (in_exception_stack(stack, info))
122 goto recursion_check;
123
124 if (in_irq_stack(stack, info))
125 goto recursion_check;
126
127 if (in_entry_stack(stack, info))
128 goto recursion_check;
129
130 goto unknown;
131
132 recursion_check:
133 /*
134 * Make sure we don't iterate through any given stack more than once.
135 * If it comes up a second time then there's something wrong going on:
136 * just break out and report an unknown stack type.
137 */
138 if (visit_mask) {
139 if (*visit_mask & (1UL << info->type)) {
140 printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type);
141 goto unknown;
142 }
143 *visit_mask |= 1UL << info->type;
144 }
145
146 return 0;
147
148 unknown:
149 info->type = STACK_TYPE_UNKNOWN;
150 return -EINVAL;
151 }
152
