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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_DB2 ] = "#DB2",
26 [ ESTACK_DB1 ] = "#DB1",
27 [ ESTACK_DB ] = "#DB",
28 [ ESTACK_MCE ] = "#MC",
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_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 */
59struct 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 */
78static const
79struct estack_pages estack_pages[CEA_ESTACK_PAGES] ____cacheline_aligned = {
80 EPAGERANGE(DF),
81 EPAGERANGE(NMI),
82 EPAGERANGE(DB1),
83 EPAGERANGE(DB),
84 EPAGERANGE(MCE),
85};
86
87static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
88{
89 unsigned long begin, end, stk = (unsigned long)stack;
90 const struct estack_pages *ep;
91 struct pt_regs *regs;
92 unsigned int k;
93
94 BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
95
96 begin = (unsigned long)__this_cpu_read(cea_exception_stacks);
97 /*
98 * Handle the case where stack trace is collected _before_
99 * cea_exception_stacks had been initialized.
100 */
101 if (!begin)
102 return false;
103
104 end = begin + sizeof(struct cea_exception_stacks);
105 /* Bail if @stack is outside the exception stack area. */
106 if (stk < begin || stk >= end)
107 return false;
108
109 /* Calc page offset from start of exception stacks */
110 k = (stk - begin) >> PAGE_SHIFT;
111 /* Lookup the page descriptor */
112 ep = &estack_pages[k];
113 /* Guard page? */
114 if (!ep->size)
115 return false;
116
117 begin += (unsigned long)ep->offs;
118 end = begin + (unsigned long)ep->size;
119 regs = (struct pt_regs *)end - 1;
120
121 info->type = ep->type;
122 info->begin = (unsigned long *)begin;
123 info->end = (unsigned long *)end;
124 info->next_sp = (unsigned long *)regs->sp;
125 return true;
126}
127
128static bool in_irq_stack(unsigned long *stack, struct stack_info *info)
129{
130 unsigned long *end = (unsigned long *)this_cpu_read(hardirq_stack_ptr);
131 unsigned long *begin = end - (IRQ_STACK_SIZE / sizeof(long));
132
133 /*
134 * This is a software stack, so 'end' can be a valid stack pointer.
135 * It just means the stack is empty.
136 */
137 if (stack < begin || stack >= end)
138 return false;
139
140 info->type = STACK_TYPE_IRQ;
141 info->begin = begin;
142 info->end = end;
143
144 /*
145 * The next stack pointer is the first thing pushed by the entry code
146 * after switching to the irq stack.
147 */
148 info->next_sp = (unsigned long *)*(end - 1);
149
150 return true;
151}
152
153int get_stack_info(unsigned long *stack, struct task_struct *task,
154 struct stack_info *info, unsigned long *visit_mask)
155{
156 if (!stack)
157 goto unknown;
158
159 task = task ? : current;
160
161 if (in_task_stack(stack, task, info))
162 goto recursion_check;
163
164 if (task != current)
165 goto unknown;
166
167 if (in_exception_stack(stack, info))
168 goto recursion_check;
169
170 if (in_irq_stack(stack, info))
171 goto recursion_check;
172
173 if (in_entry_stack(stack, info))
174 goto recursion_check;
175
176 goto unknown;
177
178recursion_check:
179 /*
180 * Make sure we don't iterate through any given stack more than once.
181 * If it comes up a second time then there's something wrong going on:
182 * just break out and report an unknown stack type.
183 */
184 if (visit_mask) {
185 if (*visit_mask & (1UL << info->type)) {
186 printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type);
187 goto unknown;
188 }
189 *visit_mask |= 1UL << info->type;
190 }
191
192 return 0;
193
194unknown:
195 info->type = STACK_TYPE_UNKNOWN;
196 return -EINVAL;
197}
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
21static 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
28static unsigned long exception_stack_sizes[N_EXCEPTION_STACKS] = {
29 [0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STKSZ,
30 [DEBUG_STACK - 1] = DEBUG_STKSZ
31};
32
33const 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
55static 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
82static 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
107int 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
132recursion_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
148unknown:
149 info->type = STACK_TYPE_UNKNOWN;
150 return -EINVAL;
151}