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/cpu_entry_area.h>
20 #include <asm/stacktrace.h>
21
22 static const char * const exception_stack_names[] = {
23 [ ESTACK_DF ] = "#DF",
24 [ ESTACK_NMI ] = "NMI",
25 [ ESTACK_DB ] = "#DB",
26 [ ESTACK_MCE ] = "#MC",
27 [ ESTACK_VC ] = "#VC",
28 [ ESTACK_VC2 ] = "#VC2",
29 };
30
stack_type_name(enum stack_type type)31 const char *stack_type_name(enum stack_type type)
32 {
33 BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
34
35 if (type == STACK_TYPE_IRQ)
36 return "IRQ";
37
38 if (type == STACK_TYPE_ENTRY) {
39 /*
40 * On 64-bit, we have a generic entry stack that we
41 * use for all the kernel entry points, including
42 * SYSENTER.
43 */
44 return "ENTRY_TRAMPOLINE";
45 }
46
47 if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
48 return exception_stack_names[type - STACK_TYPE_EXCEPTION];
49
50 return NULL;
51 }
52
53 /**
54 * struct estack_pages - Page descriptor for exception stacks
55 * @offs: Offset from the start of the exception stack area
56 * @size: Size of the exception stack
57 * @type: Type to store in the stack_info struct
58 */
59 struct estack_pages {
60 u32 offs;
61 u16 size;
62 u16 type;
63 };
64
65 #define EPAGERANGE(st) \
66 [PFN_DOWN(CEA_ESTACK_OFFS(st)) ... \
67 PFN_DOWN(CEA_ESTACK_OFFS(st) + CEA_ESTACK_SIZE(st) - 1)] = { \
68 .offs = CEA_ESTACK_OFFS(st), \
69 .size = CEA_ESTACK_SIZE(st), \
70 .type = STACK_TYPE_EXCEPTION + ESTACK_ ##st, }
71
72 /*
73 * Array of exception stack page descriptors. If the stack is larger than
74 * PAGE_SIZE, all pages covering a particular stack will have the same
75 * info. The guard pages including the not mapped DB2 stack are zeroed
76 * out.
77 */
78 static const
79 struct estack_pages estack_pages[CEA_ESTACK_PAGES] ____cacheline_aligned = {
80 EPAGERANGE(DF),
81 EPAGERANGE(NMI),
82 EPAGERANGE(DB),
83 EPAGERANGE(MCE),
84 EPAGERANGE(VC),
85 EPAGERANGE(VC2),
86 };
87
in_exception_stack(unsigned long * stack,struct stack_info * info)88 static __always_inline bool in_exception_stack(unsigned long *stack, struct stack_info *info)
89 {
90 unsigned long begin, end, stk = (unsigned long)stack;
91 const struct estack_pages *ep;
92 struct pt_regs *regs;
93 unsigned int k;
94
95 BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
96
97 begin = (unsigned long)__this_cpu_read(cea_exception_stacks);
98 /*
99 * Handle the case where stack trace is collected _before_
100 * cea_exception_stacks had been initialized.
101 */
102 if (!begin)
103 return false;
104
105 end = begin + sizeof(struct cea_exception_stacks);
106 /* Bail if @stack is outside the exception stack area. */
107 if (stk < begin || stk >= end)
108 return false;
109
110 /* Calc page offset from start of exception stacks */
111 k = (stk - begin) >> PAGE_SHIFT;
112 /* Lookup the page descriptor */
113 ep = &estack_pages[k];
114 /* Guard page? */
115 if (!ep->size)
116 return false;
117
118 begin += (unsigned long)ep->offs;
119 end = begin + (unsigned long)ep->size;
120 regs = (struct pt_regs *)end - 1;
121
122 info->type = ep->type;
123 info->begin = (unsigned long *)begin;
124 info->end = (unsigned long *)end;
125 info->next_sp = (unsigned long *)regs->sp;
126 return true;
127 }
128
in_irq_stack(unsigned long * stack,struct stack_info * info)129 static __always_inline bool in_irq_stack(unsigned long *stack, struct stack_info *info)
130 {
131 unsigned long *end = (unsigned long *)this_cpu_read(hardirq_stack_ptr);
132 unsigned long *begin = end - (IRQ_STACK_SIZE / sizeof(long));
133
134 /*
135 * This is a software stack, so 'end' can be a valid stack pointer.
136 * It just means the stack is empty.
137 */
138 if (stack < begin || stack >= end)
139 return false;
140
141 info->type = STACK_TYPE_IRQ;
142 info->begin = begin;
143 info->end = end;
144
145 /*
146 * The next stack pointer is the first thing pushed by the entry code
147 * after switching to the irq stack.
148 */
149 info->next_sp = (unsigned long *)*(end - 1);
150
151 return true;
152 }
153
get_stack_info_noinstr(unsigned long * stack,struct task_struct * task,struct stack_info * info)154 bool noinstr get_stack_info_noinstr(unsigned long *stack, struct task_struct *task,
155 struct stack_info *info)
156 {
157 if (in_task_stack(stack, task, info))
158 return true;
159
160 if (task != current)
161 return false;
162
163 if (in_exception_stack(stack, info))
164 return true;
165
166 if (in_irq_stack(stack, info))
167 return true;
168
169 if (in_entry_stack(stack, info))
170 return true;
171
172 return false;
173 }
174
get_stack_info(unsigned long * stack,struct task_struct * task,struct stack_info * info,unsigned long * visit_mask)175 int get_stack_info(unsigned long *stack, struct task_struct *task,
176 struct stack_info *info, unsigned long *visit_mask)
177 {
178 task = task ? : current;
179
180 if (!stack)
181 goto unknown;
182
183 if (!get_stack_info_noinstr(stack, task, info))
184 goto unknown;
185
186 /*
187 * Make sure we don't iterate through any given stack more than once.
188 * If it comes up a second time then there's something wrong going on:
189 * just break out and report an unknown stack type.
190 */
191 if (visit_mask) {
192 if (*visit_mask & (1UL << info->type)) {
193 if (task == current)
194 printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type);
195 goto unknown;
196 }
197 *visit_mask |= 1UL << info->type;
198 }
199
200 return 0;
201
202 unknown:
203 info->type = STACK_TYPE_UNKNOWN;
204 return -EINVAL;
205 }
206