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1// SPDX-License-Identifier: GPL-2.0-only
2/* Page Fault Handling for ARC (TLB Miss / ProtV)
3 *
4 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
5 */
6
7#include <linux/signal.h>
8#include <linux/interrupt.h>
9#include <linux/sched/signal.h>
10#include <linux/errno.h>
11#include <linux/ptrace.h>
12#include <linux/uaccess.h>
13#include <linux/kdebug.h>
14#include <linux/perf_event.h>
15#include <linux/mm_types.h>
16#include <asm/mmu.h>
17
18/*
19 * kernel virtual address is required to implement vmalloc/pkmap/fixmap
20 * Refer to asm/processor.h for System Memory Map
21 *
22 * It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
23 * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
24 */
25noinline static int handle_kernel_vaddr_fault(unsigned long address)
26{
27 /*
28 * Synchronize this task's top level page-table
29 * with the 'reference' page table.
30 */
31 pgd_t *pgd, *pgd_k;
32 p4d_t *p4d, *p4d_k;
33 pud_t *pud, *pud_k;
34 pmd_t *pmd, *pmd_k;
35
36 pgd = pgd_offset(current->active_mm, address);
37 pgd_k = pgd_offset_k(address);
38
39 if (pgd_none (*pgd_k))
40 goto bad_area;
41 if (!pgd_present(*pgd))
42 set_pgd(pgd, *pgd_k);
43
44 p4d = p4d_offset(pgd, address);
45 p4d_k = p4d_offset(pgd_k, address);
46 if (p4d_none(*p4d_k))
47 goto bad_area;
48 if (!p4d_present(*p4d))
49 set_p4d(p4d, *p4d_k);
50
51 pud = pud_offset(p4d, address);
52 pud_k = pud_offset(p4d_k, address);
53 if (pud_none(*pud_k))
54 goto bad_area;
55 if (!pud_present(*pud))
56 set_pud(pud, *pud_k);
57
58 pmd = pmd_offset(pud, address);
59 pmd_k = pmd_offset(pud_k, address);
60 if (pmd_none(*pmd_k))
61 goto bad_area;
62 if (!pmd_present(*pmd))
63 set_pmd(pmd, *pmd_k);
64
65 /* XXX: create the TLB entry here */
66 return 0;
67
68bad_area:
69 return 1;
70}
71
72void do_page_fault(unsigned long address, struct pt_regs *regs)
73{
74 struct vm_area_struct *vma = NULL;
75 struct task_struct *tsk = current;
76 struct mm_struct *mm = tsk->mm;
77 int sig, si_code = SEGV_MAPERR;
78 unsigned int write = 0, exec = 0, mask;
79 vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */
80 unsigned int flags; /* handle_mm_fault() input */
81
82 /*
83 * NOTE! We MUST NOT take any locks for this case. We may
84 * be in an interrupt or a critical region, and should
85 * only copy the information from the master page table,
86 * nothing more.
87 */
88 if (address >= VMALLOC_START && !user_mode(regs)) {
89 if (unlikely(handle_kernel_vaddr_fault(address)))
90 goto no_context;
91 else
92 return;
93 }
94
95 /*
96 * If we're in an interrupt or have no user
97 * context, we must not take the fault..
98 */
99 if (faulthandler_disabled() || !mm)
100 goto no_context;
101
102 if (regs->ecr_cause & ECR_C_PROTV_STORE) /* ST/EX */
103 write = 1;
104 else if ((regs->ecr_vec == ECR_V_PROTV) &&
105 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
106 exec = 1;
107
108 flags = FAULT_FLAG_DEFAULT;
109 if (user_mode(regs))
110 flags |= FAULT_FLAG_USER;
111 if (write)
112 flags |= FAULT_FLAG_WRITE;
113
114 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
115retry:
116 mmap_read_lock(mm);
117
118 vma = find_vma(mm, address);
119 if (!vma)
120 goto bad_area;
121 if (unlikely(address < vma->vm_start)) {
122 if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, address))
123 goto bad_area;
124 }
125
126 /*
127 * vm_area is good, now check permissions for this memory access
128 */
129 mask = VM_READ;
130 if (write)
131 mask = VM_WRITE;
132 if (exec)
133 mask = VM_EXEC;
134
135 if (!(vma->vm_flags & mask)) {
136 si_code = SEGV_ACCERR;
137 goto bad_area;
138 }
139
140 fault = handle_mm_fault(vma, address, flags, regs);
141
142 /* Quick path to respond to signals */
143 if (fault_signal_pending(fault, regs)) {
144 if (!user_mode(regs))
145 goto no_context;
146 return;
147 }
148
149 /* The fault is fully completed (including releasing mmap lock) */
150 if (fault & VM_FAULT_COMPLETED)
151 return;
152
153 /*
154 * Fault retry nuances, mmap_lock already relinquished by core mm
155 */
156 if (unlikely(fault & VM_FAULT_RETRY)) {
157 flags |= FAULT_FLAG_TRIED;
158 goto retry;
159 }
160
161bad_area:
162 mmap_read_unlock(mm);
163
164 /*
165 * Major/minor page fault accounting
166 * (in case of retry we only land here once)
167 */
168 if (likely(!(fault & VM_FAULT_ERROR)))
169 /* Normal return path: fault Handled Gracefully */
170 return;
171
172 if (!user_mode(regs))
173 goto no_context;
174
175 if (fault & VM_FAULT_OOM) {
176 pagefault_out_of_memory();
177 return;
178 }
179
180 if (fault & VM_FAULT_SIGBUS) {
181 sig = SIGBUS;
182 si_code = BUS_ADRERR;
183 }
184 else {
185 sig = SIGSEGV;
186 }
187
188 tsk->thread.fault_address = address;
189 force_sig_fault(sig, si_code, (void __user *)address);
190 return;
191
192no_context:
193 if (fixup_exception(regs))
194 return;
195
196 die("Oops", regs, address);
197}
1/* Page Fault Handling for ARC (TLB Miss / ProtV)
2 *
3 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9
10#include <linux/signal.h>
11#include <linux/interrupt.h>
12#include <linux/sched.h>
13#include <linux/errno.h>
14#include <linux/ptrace.h>
15#include <linux/uaccess.h>
16#include <linux/kdebug.h>
17#include <asm/pgalloc.h>
18#include <asm/mmu.h>
19
20static int handle_vmalloc_fault(unsigned long address)
21{
22 /*
23 * Synchronize this task's top level page-table
24 * with the 'reference' page table.
25 */
26 pgd_t *pgd, *pgd_k;
27 pud_t *pud, *pud_k;
28 pmd_t *pmd, *pmd_k;
29
30 pgd = pgd_offset_fast(current->active_mm, address);
31 pgd_k = pgd_offset_k(address);
32
33 if (!pgd_present(*pgd_k))
34 goto bad_area;
35
36 pud = pud_offset(pgd, address);
37 pud_k = pud_offset(pgd_k, address);
38 if (!pud_present(*pud_k))
39 goto bad_area;
40
41 pmd = pmd_offset(pud, address);
42 pmd_k = pmd_offset(pud_k, address);
43 if (!pmd_present(*pmd_k))
44 goto bad_area;
45
46 set_pmd(pmd, *pmd_k);
47
48 /* XXX: create the TLB entry here */
49 return 0;
50
51bad_area:
52 return 1;
53}
54
55void do_page_fault(unsigned long address, struct pt_regs *regs)
56{
57 struct vm_area_struct *vma = NULL;
58 struct task_struct *tsk = current;
59 struct mm_struct *mm = tsk->mm;
60 siginfo_t info;
61 int fault, ret;
62 int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */
63 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
64
65 /*
66 * We fault-in kernel-space virtual memory on-demand. The
67 * 'reference' page table is init_mm.pgd.
68 *
69 * NOTE! We MUST NOT take any locks for this case. We may
70 * be in an interrupt or a critical region, and should
71 * only copy the information from the master page table,
72 * nothing more.
73 */
74 if (address >= VMALLOC_START && address <= VMALLOC_END) {
75 ret = handle_vmalloc_fault(address);
76 if (unlikely(ret))
77 goto bad_area_nosemaphore;
78 else
79 return;
80 }
81
82 info.si_code = SEGV_MAPERR;
83
84 /*
85 * If we're in an interrupt or have no user
86 * context, we must not take the fault..
87 */
88 if (in_atomic() || !mm)
89 goto no_context;
90
91 if (user_mode(regs))
92 flags |= FAULT_FLAG_USER;
93retry:
94 down_read(&mm->mmap_sem);
95 vma = find_vma(mm, address);
96 if (!vma)
97 goto bad_area;
98 if (vma->vm_start <= address)
99 goto good_area;
100 if (!(vma->vm_flags & VM_GROWSDOWN))
101 goto bad_area;
102 if (expand_stack(vma, address))
103 goto bad_area;
104
105 /*
106 * Ok, we have a good vm_area for this memory access, so
107 * we can handle it..
108 */
109good_area:
110 info.si_code = SEGV_ACCERR;
111
112 /* Handle protection violation, execute on heap or stack */
113
114 if ((regs->ecr_vec == ECR_V_PROTV) &&
115 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
116 goto bad_area;
117
118 if (write) {
119 if (!(vma->vm_flags & VM_WRITE))
120 goto bad_area;
121 flags |= FAULT_FLAG_WRITE;
122 } else {
123 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
124 goto bad_area;
125 }
126
127 /*
128 * If for any reason at all we couldn't handle the fault,
129 * make sure we exit gracefully rather than endlessly redo
130 * the fault.
131 */
132 fault = handle_mm_fault(mm, vma, address, flags);
133
134 /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
135 if (unlikely(fatal_signal_pending(current))) {
136 if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY))
137 up_read(&mm->mmap_sem);
138 if (user_mode(regs))
139 return;
140 }
141
142 if (likely(!(fault & VM_FAULT_ERROR))) {
143 if (flags & FAULT_FLAG_ALLOW_RETRY) {
144 /* To avoid updating stats twice for retry case */
145 if (fault & VM_FAULT_MAJOR)
146 tsk->maj_flt++;
147 else
148 tsk->min_flt++;
149
150 if (fault & VM_FAULT_RETRY) {
151 flags &= ~FAULT_FLAG_ALLOW_RETRY;
152 flags |= FAULT_FLAG_TRIED;
153 goto retry;
154 }
155 }
156
157 /* Fault Handled Gracefully */
158 up_read(&mm->mmap_sem);
159 return;
160 }
161
162 /* TBD: switch to pagefault_out_of_memory() */
163 if (fault & VM_FAULT_OOM)
164 goto out_of_memory;
165 else if (fault & VM_FAULT_SIGBUS)
166 goto do_sigbus;
167
168 /* no man's land */
169 BUG();
170
171 /*
172 * Something tried to access memory that isn't in our memory map..
173 * Fix it, but check if it's kernel or user first..
174 */
175bad_area:
176 up_read(&mm->mmap_sem);
177
178bad_area_nosemaphore:
179 /* User mode accesses just cause a SIGSEGV */
180 if (user_mode(regs)) {
181 tsk->thread.fault_address = address;
182 info.si_signo = SIGSEGV;
183 info.si_errno = 0;
184 /* info.si_code has been set above */
185 info.si_addr = (void __user *)address;
186 force_sig_info(SIGSEGV, &info, tsk);
187 return;
188 }
189
190no_context:
191 /* Are we prepared to handle this kernel fault?
192 *
193 * (The kernel has valid exception-points in the source
194 * when it acesses user-memory. When it fails in one
195 * of those points, we find it in a table and do a jump
196 * to some fixup code that loads an appropriate error
197 * code)
198 */
199 if (fixup_exception(regs))
200 return;
201
202 die("Oops", regs, address);
203
204out_of_memory:
205 up_read(&mm->mmap_sem);
206
207 if (user_mode(regs)) {
208 pagefault_out_of_memory();
209 return;
210 }
211
212 goto no_context;
213
214do_sigbus:
215 up_read(&mm->mmap_sem);
216
217 if (!user_mode(regs))
218 goto no_context;
219
220 tsk->thread.fault_address = address;
221 info.si_signo = SIGBUS;
222 info.si_errno = 0;
223 info.si_code = BUS_ADRERR;
224 info.si_addr = (void __user *)address;
225 force_sig_info(SIGBUS, &info, tsk);
226}