1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Memory fault handling for Hexagon
4 *
5 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
6 */
7
8 /*
9 * Page fault handling for the Hexagon Virtual Machine.
10 * Can also be called by a native port emulating the HVM
11 * execptions.
12 */
13
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 * Decode of hardware exception sends us to one of several
25 * entry points. At each, we generate canonical arguments
26 * for handling by the abstract memory management code.
27 */
28 #define FLT_IFETCH -1
29 #define FLT_LOAD 0
30 #define FLT_STORE 1
31
32
33 /*
34 * Canonical page fault handler
35 */
do_page_fault(unsigned long address,long cause,struct pt_regs * regs)36 void 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 * If we're in an interrupt or have no user context,
48 * then must not take the fault.
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);
59 retry:
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
74 good_area:
75 /* Address space is OK. Now check access rights. */
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 /* The fault is fully completed (including releasing mmap lock) */
100 if (fault & VM_FAULT_COMPLETED)
101 return;
102
103 /* The most common case -- we are done. */
104 if (likely(!(fault & VM_FAULT_ERROR))) {
105 if (fault & VM_FAULT_RETRY) {
106 flags |= FAULT_FLAG_TRIED;
107 goto retry;
108 }
109
110 mmap_read_unlock(mm);
111 return;
112 }
113
114 mmap_read_unlock(mm);
115
116 /* Handle copyin/out exception cases */
117 if (!user_mode(regs))
118 goto no_context;
119
120 if (fault & VM_FAULT_OOM) {
121 pagefault_out_of_memory();
122 return;
123 }
124
125 /* User-mode address is in the memory map, but we are
126 * unable to fix up the page fault.
127 */
128 if (fault & VM_FAULT_SIGBUS) {
129 si_signo = SIGBUS;
130 si_code = BUS_ADRERR;
131 }
132 /* Address is not in the memory map */
133 else {
134 si_signo = SIGSEGV;
135 si_code = SEGV_ACCERR;
136 }
137 force_sig_fault(si_signo, si_code, (void __user *)address);
138 return;
139
140 bad_area:
141 mmap_read_unlock(mm);
142
143 if (user_mode(regs)) {
144 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
145 return;
146 }
147 /* Kernel-mode fault falls through */
148
149 no_context:
150 fixup = search_exception_tables(pt_elr(regs));
151 if (fixup) {
152 pt_set_elr(regs, fixup->fixup);
153 return;
154 }
155
156 /* Things are looking very, very bad now */
157 bust_spinlocks(1);
158 printk(KERN_EMERG "Unable to handle kernel paging request at "
159 "virtual address 0x%08lx, regs %p\n", address, regs);
160 die("Bad Kernel VA", regs, SIGKILL);
161 }
162
163
read_protection_fault(struct pt_regs * regs)164 void read_protection_fault(struct pt_regs *regs)
165 {
166 unsigned long badvadr = pt_badva(regs);
167
168 do_page_fault(badvadr, FLT_LOAD, regs);
169 }
170
write_protection_fault(struct pt_regs * regs)171 void write_protection_fault(struct pt_regs *regs)
172 {
173 unsigned long badvadr = pt_badva(regs);
174
175 do_page_fault(badvadr, FLT_STORE, regs);
176 }
177
execute_protection_fault(struct pt_regs * regs)178 void execute_protection_fault(struct pt_regs *regs)
179 {
180 unsigned long badvadr = pt_badva(regs);
181
182 do_page_fault(badvadr, FLT_IFETCH, regs);
183 }
184