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14#include <asm/traps.h>
15#include <linux/uaccess.h>
16#include <linux/mm.h>
17#include <linux/sched/signal.h>
18#include <linux/signal.h>
19#include <linux/extable.h>
20#include <linux/hardirq.h>
21#include <linux/perf_event.h>
22
23
24
25
26
27
28#define FLT_IFETCH -1
29#define FLT_LOAD 0
30#define FLT_STORE 1
31
32
33
34
35
36void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
37{
38 struct vm_area_struct *vma;
39 struct mm_struct *mm = current->mm;
40 int si_signo;
41 int si_code = SEGV_MAPERR;
42 vm_fault_t fault;
43 const struct exception_table_entry *fixup;
44 unsigned int flags = FAULT_FLAG_DEFAULT;
45
46
47
48
49
50 if (unlikely(in_interrupt() || !mm))
51 goto no_context;
52
53 local_irq_enable();
54
55 if (user_mode(regs))
56 flags |= FAULT_FLAG_USER;
57
58 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
59retry:
60 mmap_read_lock(mm);
61 vma = find_vma(mm, address);
62 if (!vma)
63 goto bad_area;
64
65 if (vma->vm_start <= address)
66 goto good_area;
67
68 if (!(vma->vm_flags & VM_GROWSDOWN))
69 goto bad_area;
70
71 if (expand_stack(vma, address))
72 goto bad_area;
73
74good_area:
75
76 si_code = SEGV_ACCERR;
77
78 switch (cause) {
79 case FLT_IFETCH:
80 if (!(vma->vm_flags & VM_EXEC))
81 goto bad_area;
82 break;
83 case FLT_LOAD:
84 if (!(vma->vm_flags & VM_READ))
85 goto bad_area;
86 break;
87 case FLT_STORE:
88 if (!(vma->vm_flags & VM_WRITE))
89 goto bad_area;
90 flags |= FAULT_FLAG_WRITE;
91 break;
92 }
93
94 fault = handle_mm_fault(vma, address, flags, regs);
95
96 if (fault_signal_pending(fault, regs))
97 return;
98
99
100 if (likely(!(fault & VM_FAULT_ERROR))) {
101 if (flags & FAULT_FLAG_ALLOW_RETRY) {
102 if (fault & VM_FAULT_RETRY) {
103 flags |= FAULT_FLAG_TRIED;
104 goto retry;
105 }
106 }
107
108 mmap_read_unlock(mm);
109 return;
110 }
111
112 mmap_read_unlock(mm);
113
114
115 if (!user_mode(regs))
116 goto no_context;
117
118 if (fault & VM_FAULT_OOM) {
119 pagefault_out_of_memory();
120 return;
121 }
122
123
124
125
126 if (fault & VM_FAULT_SIGBUS) {
127 si_signo = SIGBUS;
128 si_code = BUS_ADRERR;
129 }
130
131 else {
132 si_signo = SIGSEGV;
133 si_code = SEGV_ACCERR;
134 }
135 force_sig_fault(si_signo, si_code, (void __user *)address);
136 return;
137
138bad_area:
139 mmap_read_unlock(mm);
140
141 if (user_mode(regs)) {
142 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
143 return;
144 }
145
146
147no_context:
148 fixup = search_exception_tables(pt_elr(regs));
149 if (fixup) {
150 pt_set_elr(regs, fixup->fixup);
151 return;
152 }
153
154
155 bust_spinlocks(1);
156 printk(KERN_EMERG "Unable to handle kernel paging request at "
157 "virtual address 0x%08lx, regs %p\n", address, regs);
158 die("Bad Kernel VA", regs, SIGKILL);
159}
160
161
162void read_protection_fault(struct pt_regs *regs)
163{
164 unsigned long badvadr = pt_badva(regs);
165
166 do_page_fault(badvadr, FLT_LOAD, regs);
167}
168
169void write_protection_fault(struct pt_regs *regs)
170{
171 unsigned long badvadr = pt_badva(regs);
172
173 do_page_fault(badvadr, FLT_STORE, regs);
174}
175
176void execute_protection_fault(struct pt_regs *regs)
177{
178 unsigned long badvadr = pt_badva(regs);
179
180 do_page_fault(badvadr, FLT_IFETCH, regs);
181}
182