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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/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};
28
29const char *stack_type_name(enum stack_type type)
30{
31 BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
32
33 if (type == STACK_TYPE_IRQ)
34 return "IRQ";
35
36 if (type == STACK_TYPE_ENTRY) {
37 /*
38 * On 64-bit, we have a generic entry stack that we
39 * use for all the kernel entry points, including
40 * SYSENTER.
41 */
42 return "ENTRY_TRAMPOLINE";
43 }
44
45 if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
46 return exception_stack_names[type - STACK_TYPE_EXCEPTION];
47
48 return NULL;
49}
50
51/**
52 * struct estack_pages - Page descriptor for exception stacks
53 * @offs: Offset from the start of the exception stack area
54 * @size: Size of the exception stack
55 * @type: Type to store in the stack_info struct
56 */
57struct estack_pages {
58 u32 offs;
59 u16 size;
60 u16 type;
61};
62
63#define EPAGERANGE(st) \
64 [PFN_DOWN(CEA_ESTACK_OFFS(st)) ... \
65 PFN_DOWN(CEA_ESTACK_OFFS(st) + CEA_ESTACK_SIZE(st) - 1)] = { \
66 .offs = CEA_ESTACK_OFFS(st), \
67 .size = CEA_ESTACK_SIZE(st), \
68 .type = STACK_TYPE_EXCEPTION + ESTACK_ ##st, }
69
70/*
71 * Array of exception stack page descriptors. If the stack is larger than
72 * PAGE_SIZE, all pages covering a particular stack will have the same
73 * info. The guard pages including the not mapped DB2 stack are zeroed
74 * out.
75 */
76static const
77struct estack_pages estack_pages[CEA_ESTACK_PAGES] ____cacheline_aligned = {
78 EPAGERANGE(DF),
79 EPAGERANGE(NMI),
80 EPAGERANGE(DB),
81 EPAGERANGE(MCE),
82};
83
84static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
85{
86 unsigned long begin, end, stk = (unsigned long)stack;
87 const struct estack_pages *ep;
88 struct pt_regs *regs;
89 unsigned int k;
90
91 BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
92
93 begin = (unsigned long)__this_cpu_read(cea_exception_stacks);
94 /*
95 * Handle the case where stack trace is collected _before_
96 * cea_exception_stacks had been initialized.
97 */
98 if (!begin)
99 return false;
100
101 end = begin + sizeof(struct cea_exception_stacks);
102 /* Bail if @stack is outside the exception stack area. */
103 if (stk < begin || stk >= end)
104 return false;
105
106 /* Calc page offset from start of exception stacks */
107 k = (stk - begin) >> PAGE_SHIFT;
108 /* Lookup the page descriptor */
109 ep = &estack_pages[k];
110 /* Guard page? */
111 if (!ep->size)
112 return false;
113
114 begin += (unsigned long)ep->offs;
115 end = begin + (unsigned long)ep->size;
116 regs = (struct pt_regs *)end - 1;
117
118 info->type = ep->type;
119 info->begin = (unsigned long *)begin;
120 info->end = (unsigned long *)end;
121 info->next_sp = (unsigned long *)regs->sp;
122 return true;
123}
124
125static bool in_irq_stack(unsigned long *stack, struct stack_info *info)
126{
127 unsigned long *end = (unsigned long *)this_cpu_read(hardirq_stack_ptr);
128 unsigned long *begin = end - (IRQ_STACK_SIZE / sizeof(long));
129
130 /*
131 * This is a software stack, so 'end' can be a valid stack pointer.
132 * It just means the stack is empty.
133 */
134 if (stack < begin || stack >= end)
135 return false;
136
137 info->type = STACK_TYPE_IRQ;
138 info->begin = begin;
139 info->end = end;
140
141 /*
142 * The next stack pointer is the first thing pushed by the entry code
143 * after switching to the irq stack.
144 */
145 info->next_sp = (unsigned long *)*(end - 1);
146
147 return true;
148}
149
150int get_stack_info(unsigned long *stack, struct task_struct *task,
151 struct stack_info *info, unsigned long *visit_mask)
152{
153 if (!stack)
154 goto unknown;
155
156 task = task ? : current;
157
158 if (in_task_stack(stack, task, info))
159 goto recursion_check;
160
161 if (task != current)
162 goto unknown;
163
164 if (in_exception_stack(stack, info))
165 goto recursion_check;
166
167 if (in_irq_stack(stack, info))
168 goto recursion_check;
169
170 if (in_entry_stack(stack, info))
171 goto recursion_check;
172
173 goto unknown;
174
175recursion_check:
176 /*
177 * Make sure we don't iterate through any given stack more than once.
178 * If it comes up a second time then there's something wrong going on:
179 * just break out and report an unknown stack type.
180 */
181 if (visit_mask) {
182 if (*visit_mask & (1UL << info->type)) {
183 if (task == current)
184 printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type);
185 goto unknown;
186 }
187 *visit_mask |= 1UL << info->type;
188 }
189
190 return 0;
191
192unknown:
193 info->type = STACK_TYPE_UNKNOWN;
194 return -EINVAL;
195}