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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
22static 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
31const char *stack_type_name(enum stack_type type)
32{
33 BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
34
35 if (type == STACK_TYPE_TASK)
36 return "TASK";
37
38 if (type == STACK_TYPE_IRQ)
39 return "IRQ";
40
41 if (type == STACK_TYPE_SOFTIRQ)
42 return "SOFTIRQ";
43
44 if (type == STACK_TYPE_ENTRY) {
45 /*
46 * On 64-bit, we have a generic entry stack that we
47 * use for all the kernel entry points, including
48 * SYSENTER.
49 */
50 return "ENTRY_TRAMPOLINE";
51 }
52
53 if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
54 return exception_stack_names[type - STACK_TYPE_EXCEPTION];
55
56 return NULL;
57}
58
59/**
60 * struct estack_pages - Page descriptor for exception stacks
61 * @offs: Offset from the start of the exception stack area
62 * @size: Size of the exception stack
63 * @type: Type to store in the stack_info struct
64 */
65struct estack_pages {
66 u32 offs;
67 u16 size;
68 u16 type;
69};
70
71#define EPAGERANGE(st) \
72 [PFN_DOWN(CEA_ESTACK_OFFS(st)) ... \
73 PFN_DOWN(CEA_ESTACK_OFFS(st) + CEA_ESTACK_SIZE(st) - 1)] = { \
74 .offs = CEA_ESTACK_OFFS(st), \
75 .size = CEA_ESTACK_SIZE(st), \
76 .type = STACK_TYPE_EXCEPTION + ESTACK_ ##st, }
77
78/*
79 * Array of exception stack page descriptors. If the stack is larger than
80 * PAGE_SIZE, all pages covering a particular stack will have the same
81 * info. The guard pages including the not mapped DB2 stack are zeroed
82 * out.
83 */
84static const
85struct estack_pages estack_pages[CEA_ESTACK_PAGES] ____cacheline_aligned = {
86 EPAGERANGE(DF),
87 EPAGERANGE(NMI),
88 EPAGERANGE(DB),
89 EPAGERANGE(MCE),
90 EPAGERANGE(VC),
91 EPAGERANGE(VC2),
92};
93
94static __always_inline bool in_exception_stack(unsigned long *stack, struct stack_info *info)
95{
96 unsigned long begin, end, stk = (unsigned long)stack;
97 const struct estack_pages *ep;
98 struct pt_regs *regs;
99 unsigned int k;
100
101 BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
102
103 begin = (unsigned long)__this_cpu_read(cea_exception_stacks);
104 /*
105 * Handle the case where stack trace is collected _before_
106 * cea_exception_stacks had been initialized.
107 */
108 if (!begin)
109 return false;
110
111 end = begin + sizeof(struct cea_exception_stacks);
112 /* Bail if @stack is outside the exception stack area. */
113 if (stk < begin || stk >= end)
114 return false;
115
116 /* Calc page offset from start of exception stacks */
117 k = (stk - begin) >> PAGE_SHIFT;
118 /* Lookup the page descriptor */
119 ep = &estack_pages[k];
120 /* Guard page? */
121 if (!ep->size)
122 return false;
123
124 begin += (unsigned long)ep->offs;
125 end = begin + (unsigned long)ep->size;
126 regs = (struct pt_regs *)end - 1;
127
128 info->type = ep->type;
129 info->begin = (unsigned long *)begin;
130 info->end = (unsigned long *)end;
131 info->next_sp = (unsigned long *)regs->sp;
132 return true;
133}
134
135static __always_inline bool in_irq_stack(unsigned long *stack, struct stack_info *info)
136{
137 unsigned long *end = (unsigned long *)this_cpu_read(hardirq_stack_ptr);
138 unsigned long *begin;
139
140 /*
141 * @end points directly to the top most stack entry to avoid a -8
142 * adjustment in the stack switch hotpath. Adjust it back before
143 * calculating @begin.
144 */
145 end++;
146 begin = end - (IRQ_STACK_SIZE / sizeof(long));
147
148 /*
149 * Due to the switching logic RSP can never be == @end because the
150 * final operation is 'popq %rsp' which means after that RSP points
151 * to the original stack and not to @end.
152 */
153 if (stack < begin || stack >= end)
154 return false;
155
156 info->type = STACK_TYPE_IRQ;
157 info->begin = begin;
158 info->end = end;
159
160 /*
161 * The next stack pointer is stored at the top of the irq stack
162 * before switching to the irq stack. Actual stack entries are all
163 * below that.
164 */
165 info->next_sp = (unsigned long *)*(end - 1);
166
167 return true;
168}
169
170bool noinstr get_stack_info_noinstr(unsigned long *stack, struct task_struct *task,
171 struct stack_info *info)
172{
173 if (in_task_stack(stack, task, info))
174 return true;
175
176 if (task != current)
177 return false;
178
179 if (in_exception_stack(stack, info))
180 return true;
181
182 if (in_irq_stack(stack, info))
183 return true;
184
185 if (in_entry_stack(stack, info))
186 return true;
187
188 return false;
189}
190
191int get_stack_info(unsigned long *stack, struct task_struct *task,
192 struct stack_info *info, unsigned long *visit_mask)
193{
194 task = task ? : current;
195
196 if (!stack)
197 goto unknown;
198
199 if (!get_stack_info_noinstr(stack, task, info))
200 goto unknown;
201
202 /*
203 * Make sure we don't iterate through any given stack more than once.
204 * If it comes up a second time then there's something wrong going on:
205 * just break out and report an unknown stack type.
206 */
207 if (visit_mask) {
208 if (*visit_mask & (1UL << info->type)) {
209 if (task == current)
210 printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type);
211 goto unknown;
212 }
213 *visit_mask |= 1UL << info->type;
214 }
215
216 return 0;
217
218unknown:
219 info->type = STACK_TYPE_UNKNOWN;
220 return -EINVAL;
221}