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1/*
2 * Memory fault handling for Hexagon
3 *
4 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 and
8 * only version 2 as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
18 * 02110-1301, USA.
19 */
20
21/*
22 * Page fault handling for the Hexagon Virtual Machine.
23 * Can also be called by a native port emulating the HVM
24 * execptions.
25 */
26
27#include <asm/pgtable.h>
28#include <asm/traps.h>
29#include <linux/uaccess.h>
30#include <linux/mm.h>
31#include <linux/sched/signal.h>
32#include <linux/signal.h>
33#include <linux/extable.h>
34#include <linux/hardirq.h>
35
36/*
37 * Decode of hardware exception sends us to one of several
38 * entry points. At each, we generate canonical arguments
39 * for handling by the abstract memory management code.
40 */
41#define FLT_IFETCH -1
42#define FLT_LOAD 0
43#define FLT_STORE 1
44
45
46/*
47 * Canonical page fault handler
48 */
49void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
50{
51 struct vm_area_struct *vma;
52 struct mm_struct *mm = current->mm;
53 siginfo_t info;
54 int si_code = SEGV_MAPERR;
55 int fault;
56 const struct exception_table_entry *fixup;
57 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
58
59 /*
60 * If we're in an interrupt or have no user context,
61 * then must not take the fault.
62 */
63 if (unlikely(in_interrupt() || !mm))
64 goto no_context;
65
66 local_irq_enable();
67
68 if (user_mode(regs))
69 flags |= FAULT_FLAG_USER;
70retry:
71 down_read(&mm->mmap_sem);
72 vma = find_vma(mm, address);
73 if (!vma)
74 goto bad_area;
75
76 if (vma->vm_start <= address)
77 goto good_area;
78
79 if (!(vma->vm_flags & VM_GROWSDOWN))
80 goto bad_area;
81
82 if (expand_stack(vma, address))
83 goto bad_area;
84
85good_area:
86 /* Address space is OK. Now check access rights. */
87 si_code = SEGV_ACCERR;
88
89 switch (cause) {
90 case FLT_IFETCH:
91 if (!(vma->vm_flags & VM_EXEC))
92 goto bad_area;
93 break;
94 case FLT_LOAD:
95 if (!(vma->vm_flags & VM_READ))
96 goto bad_area;
97 break;
98 case FLT_STORE:
99 if (!(vma->vm_flags & VM_WRITE))
100 goto bad_area;
101 flags |= FAULT_FLAG_WRITE;
102 break;
103 }
104
105 fault = handle_mm_fault(vma, address, flags);
106
107 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
108 return;
109
110 /* The most common case -- we are done. */
111 if (likely(!(fault & VM_FAULT_ERROR))) {
112 if (flags & FAULT_FLAG_ALLOW_RETRY) {
113 if (fault & VM_FAULT_MAJOR)
114 current->maj_flt++;
115 else
116 current->min_flt++;
117 if (fault & VM_FAULT_RETRY) {
118 flags &= ~FAULT_FLAG_ALLOW_RETRY;
119 flags |= FAULT_FLAG_TRIED;
120 goto retry;
121 }
122 }
123
124 up_read(&mm->mmap_sem);
125 return;
126 }
127
128 up_read(&mm->mmap_sem);
129
130 /* Handle copyin/out exception cases */
131 if (!user_mode(regs))
132 goto no_context;
133
134 if (fault & VM_FAULT_OOM) {
135 pagefault_out_of_memory();
136 return;
137 }
138
139 /* User-mode address is in the memory map, but we are
140 * unable to fix up the page fault.
141 */
142 if (fault & VM_FAULT_SIGBUS) {
143 info.si_signo = SIGBUS;
144 info.si_code = BUS_ADRERR;
145 }
146 /* Address is not in the memory map */
147 else {
148 info.si_signo = SIGSEGV;
149 info.si_code = SEGV_ACCERR;
150 }
151 info.si_errno = 0;
152 info.si_addr = (void __user *)address;
153 force_sig_info(info.si_signo, &info, current);
154 return;
155
156bad_area:
157 up_read(&mm->mmap_sem);
158
159 if (user_mode(regs)) {
160 info.si_signo = SIGSEGV;
161 info.si_errno = 0;
162 info.si_code = si_code;
163 info.si_addr = (void *)address;
164 force_sig_info(info.si_signo, &info, current);
165 return;
166 }
167 /* Kernel-mode fault falls through */
168
169no_context:
170 fixup = search_exception_tables(pt_elr(regs));
171 if (fixup) {
172 pt_set_elr(regs, fixup->fixup);
173 return;
174 }
175
176 /* Things are looking very, very bad now */
177 bust_spinlocks(1);
178 printk(KERN_EMERG "Unable to handle kernel paging request at "
179 "virtual address 0x%08lx, regs %p\n", address, regs);
180 die("Bad Kernel VA", regs, SIGKILL);
181}
182
183
184void read_protection_fault(struct pt_regs *regs)
185{
186 unsigned long badvadr = pt_badva(regs);
187
188 do_page_fault(badvadr, FLT_LOAD, regs);
189}
190
191void write_protection_fault(struct pt_regs *regs)
192{
193 unsigned long badvadr = pt_badva(regs);
194
195 do_page_fault(badvadr, FLT_STORE, regs);
196}
197
198void execute_protection_fault(struct pt_regs *regs)
199{
200 unsigned long badvadr = pt_badva(regs);
201
202 do_page_fault(badvadr, FLT_IFETCH, regs);
203}
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 <asm/vm_fault.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#include <linux/perf_event.h>
23
24/*
25 * Decode of hardware exception sends us to one of several
26 * entry points. At each, we generate canonical arguments
27 * for handling by the abstract memory management code.
28 */
29#define FLT_IFETCH -1
30#define FLT_LOAD 0
31#define FLT_STORE 1
32
33
34/*
35 * Canonical page fault handler
36 */
37static void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
38{
39 struct vm_area_struct *vma;
40 struct mm_struct *mm = current->mm;
41 int si_signo;
42 int si_code = SEGV_MAPERR;
43 vm_fault_t fault;
44 const struct exception_table_entry *fixup;
45 unsigned int flags = FAULT_FLAG_DEFAULT;
46
47 /*
48 * If we're in an interrupt or have no user context,
49 * then must not take the fault.
50 */
51 if (unlikely(in_interrupt() || !mm))
52 goto no_context;
53
54 local_irq_enable();
55
56 if (user_mode(regs))
57 flags |= FAULT_FLAG_USER;
58
59 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
60retry:
61 vma = lock_mm_and_find_vma(mm, address, regs);
62 if (unlikely(!vma))
63 goto bad_area_nosemaphore;
64
65 /* Address space is OK. Now check access rights. */
66 si_code = SEGV_ACCERR;
67
68 switch (cause) {
69 case FLT_IFETCH:
70 if (!(vma->vm_flags & VM_EXEC))
71 goto bad_area;
72 break;
73 case FLT_LOAD:
74 if (!(vma->vm_flags & VM_READ))
75 goto bad_area;
76 break;
77 case FLT_STORE:
78 if (!(vma->vm_flags & VM_WRITE))
79 goto bad_area;
80 flags |= FAULT_FLAG_WRITE;
81 break;
82 }
83
84 fault = handle_mm_fault(vma, address, flags, regs);
85
86 if (fault_signal_pending(fault, regs)) {
87 if (!user_mode(regs))
88 goto no_context;
89 return;
90 }
91
92 /* The fault is fully completed (including releasing mmap lock) */
93 if (fault & VM_FAULT_COMPLETED)
94 return;
95
96 /* The most common case -- we are done. */
97 if (likely(!(fault & VM_FAULT_ERROR))) {
98 if (fault & VM_FAULT_RETRY) {
99 flags |= FAULT_FLAG_TRIED;
100 goto retry;
101 }
102
103 mmap_read_unlock(mm);
104 return;
105 }
106
107 mmap_read_unlock(mm);
108
109 /* Handle copyin/out exception cases */
110 if (!user_mode(regs))
111 goto no_context;
112
113 if (fault & VM_FAULT_OOM) {
114 pagefault_out_of_memory();
115 return;
116 }
117
118 /* User-mode address is in the memory map, but we are
119 * unable to fix up the page fault.
120 */
121 if (fault & VM_FAULT_SIGBUS) {
122 si_signo = SIGBUS;
123 si_code = BUS_ADRERR;
124 }
125 /* Address is not in the memory map */
126 else {
127 si_signo = SIGSEGV;
128 si_code = SEGV_ACCERR;
129 }
130 force_sig_fault(si_signo, si_code, (void __user *)address);
131 return;
132
133bad_area:
134 mmap_read_unlock(mm);
135
136bad_area_nosemaphore:
137 if (user_mode(regs)) {
138 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
139 return;
140 }
141 /* Kernel-mode fault falls through */
142
143no_context:
144 fixup = search_exception_tables(pt_elr(regs));
145 if (fixup) {
146 pt_set_elr(regs, fixup->fixup);
147 return;
148 }
149
150 /* Things are looking very, very bad now */
151 bust_spinlocks(1);
152 printk(KERN_EMERG "Unable to handle kernel paging request at "
153 "virtual address 0x%08lx, regs %p\n", address, regs);
154 die("Bad Kernel VA", regs, SIGKILL);
155}
156
157
158void read_protection_fault(struct pt_regs *regs)
159{
160 unsigned long badvadr = pt_badva(regs);
161
162 do_page_fault(badvadr, FLT_LOAD, regs);
163}
164
165void write_protection_fault(struct pt_regs *regs)
166{
167 unsigned long badvadr = pt_badva(regs);
168
169 do_page_fault(badvadr, FLT_STORE, regs);
170}
171
172void execute_protection_fault(struct pt_regs *regs)
173{
174 unsigned long badvadr = pt_badva(regs);
175
176 do_page_fault(badvadr, FLT_IFETCH, regs);
177}