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/pgtable.h>
15 #include <asm/traps.h>
16 #include <linux/uaccess.h>
17 #include <linux/mm.h>
18 #include <linux/sched/signal.h>
19 #include <linux/signal.h>
20 #include <linux/extable.h>
21 #include <linux/hardirq.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_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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 retry:
58 down_read(&mm->mmap_sem);
59 vma = find_vma(mm, address);
60 if (!vma)
61 goto bad_area;
62
63 if (vma->vm_start <= address)
64 goto good_area;
65
66 if (!(vma->vm_flags & VM_GROWSDOWN))
67 goto bad_area;
68
69 if (expand_stack(vma, address))
70 goto bad_area;
71
72 good_area:
73 /* Address space is OK. Now check access rights. */
74 si_code = SEGV_ACCERR;
75
76 switch (cause) {
77 case FLT_IFETCH:
78 if (!(vma->vm_flags & VM_EXEC))
79 goto bad_area;
80 break;
81 case FLT_LOAD:
82 if (!(vma->vm_flags & VM_READ))
83 goto bad_area;
84 break;
85 case FLT_STORE:
86 if (!(vma->vm_flags & VM_WRITE))
87 goto bad_area;
88 flags |= FAULT_FLAG_WRITE;
89 break;
90 }
91
92 fault = handle_mm_fault(vma, address, flags);
93
94 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
95 return;
96
97 /* The most common case -- we are done. */
98 if (likely(!(fault & VM_FAULT_ERROR))) {
99 if (flags & FAULT_FLAG_ALLOW_RETRY) {
100 if (fault & VM_FAULT_MAJOR)
101 current->maj_flt++;
102 else
103 current->min_flt++;
104 if (fault & VM_FAULT_RETRY) {
105 flags &= ~FAULT_FLAG_ALLOW_RETRY;
106 flags |= FAULT_FLAG_TRIED;
107 goto retry;
108 }
109 }
110
111 up_read(&mm->mmap_sem);
112 return;
113 }
114
115 up_read(&mm->mmap_sem);
116
117 /* Handle copyin/out exception cases */
118 if (!user_mode(regs))
119 goto no_context;
120
121 if (fault & VM_FAULT_OOM) {
122 pagefault_out_of_memory();
123 return;
124 }
125
126 /* User-mode address is in the memory map, but we are
127 * unable to fix up the page fault.
128 */
129 if (fault & VM_FAULT_SIGBUS) {
130 si_signo = SIGBUS;
131 si_code = BUS_ADRERR;
132 }
133 /* Address is not in the memory map */
134 else {
135 si_signo = SIGSEGV;
136 si_code = SEGV_ACCERR;
137 }
138 force_sig_fault(si_signo, si_code, (void __user *)address);
139 return;
140
141 bad_area:
142 up_read(&mm->mmap_sem);
143
144 if (user_mode(regs)) {
145 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
146 return;
147 }
148 /* Kernel-mode fault falls through */
149
150 no_context:
151 fixup = search_exception_tables(pt_elr(regs));
152 if (fixup) {
153 pt_set_elr(regs, fixup->fixup);
154 return;
155 }
156
157 /* Things are looking very, very bad now */
158 bust_spinlocks(1);
159 printk(KERN_EMERG "Unable to handle kernel paging request at "
160 "virtual address 0x%08lx, regs %p\n", address, regs);
161 die("Bad Kernel VA", regs, SIGKILL);
162 }
163
164
read_protection_fault(struct pt_regs * regs)165 void read_protection_fault(struct pt_regs *regs)
166 {
167 unsigned long badvadr = pt_badva(regs);
168
169 do_page_fault(badvadr, FLT_LOAD, regs);
170 }
171
write_protection_fault(struct pt_regs * regs)172 void write_protection_fault(struct pt_regs *regs)
173 {
174 unsigned long badvadr = pt_badva(regs);
175
176 do_page_fault(badvadr, FLT_STORE, regs);
177 }
178
execute_protection_fault(struct pt_regs * regs)179 void execute_protection_fault(struct pt_regs *regs)
180 {
181 unsigned long badvadr = pt_badva(regs);
182
183 do_page_fault(badvadr, FLT_IFETCH, regs);
184 }
185
