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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_fast(current->active_mm, address);
37 pgd_k = pgd_offset_k(address);
38
39 if (!pgd_present(*pgd_k))
40 goto bad_area;
41
42 p4d = p4d_offset(pgd, address);
43 p4d_k = p4d_offset(pgd_k, address);
44 if (!p4d_present(*p4d_k))
45 goto bad_area;
46
47 pud = pud_offset(p4d, address);
48 pud_k = pud_offset(p4d_k, address);
49 if (!pud_present(*pud_k))
50 goto bad_area;
51
52 pmd = pmd_offset(pud, address);
53 pmd_k = pmd_offset(pud_k, address);
54 if (!pmd_present(*pmd_k))
55 goto bad_area;
56
57 set_pmd(pmd, *pmd_k);
58
59 /* XXX: create the TLB entry here */
60 return 0;
61
62bad_area:
63 return 1;
64}
65
66void do_page_fault(unsigned long address, struct pt_regs *regs)
67{
68 struct vm_area_struct *vma = NULL;
69 struct task_struct *tsk = current;
70 struct mm_struct *mm = tsk->mm;
71 int sig, si_code = SEGV_MAPERR;
72 unsigned int write = 0, exec = 0, mask;
73 vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */
74 unsigned int flags; /* handle_mm_fault() input */
75
76 /*
77 * NOTE! We MUST NOT take any locks for this case. We may
78 * be in an interrupt or a critical region, and should
79 * only copy the information from the master page table,
80 * nothing more.
81 */
82 if (address >= VMALLOC_START && !user_mode(regs)) {
83 if (unlikely(handle_kernel_vaddr_fault(address)))
84 goto no_context;
85 else
86 return;
87 }
88
89 /*
90 * If we're in an interrupt or have no user
91 * context, we must not take the fault..
92 */
93 if (faulthandler_disabled() || !mm)
94 goto no_context;
95
96 if (regs->ecr_cause & ECR_C_PROTV_STORE) /* ST/EX */
97 write = 1;
98 else if ((regs->ecr_vec == ECR_V_PROTV) &&
99 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
100 exec = 1;
101
102 flags = FAULT_FLAG_DEFAULT;
103 if (user_mode(regs))
104 flags |= FAULT_FLAG_USER;
105 if (write)
106 flags |= FAULT_FLAG_WRITE;
107
108 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
109retry:
110 mmap_read_lock(mm);
111
112 vma = find_vma(mm, address);
113 if (!vma)
114 goto bad_area;
115 if (unlikely(address < vma->vm_start)) {
116 if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, address))
117 goto bad_area;
118 }
119
120 /*
121 * vm_area is good, now check permissions for this memory access
122 */
123 mask = VM_READ;
124 if (write)
125 mask = VM_WRITE;
126 if (exec)
127 mask = VM_EXEC;
128
129 if (!(vma->vm_flags & mask)) {
130 si_code = SEGV_ACCERR;
131 goto bad_area;
132 }
133
134 fault = handle_mm_fault(vma, address, flags, regs);
135
136 /* Quick path to respond to signals */
137 if (fault_signal_pending(fault, regs)) {
138 if (!user_mode(regs))
139 goto no_context;
140 return;
141 }
142
143 /*
144 * Fault retry nuances, mmap_lock already relinquished by core mm
145 */
146 if (unlikely((fault & VM_FAULT_RETRY) &&
147 (flags & FAULT_FLAG_ALLOW_RETRY))) {
148 flags |= FAULT_FLAG_TRIED;
149 goto retry;
150 }
151
152bad_area:
153 mmap_read_unlock(mm);
154
155 /*
156 * Major/minor page fault accounting
157 * (in case of retry we only land here once)
158 */
159 if (likely(!(fault & VM_FAULT_ERROR)))
160 /* Normal return path: fault Handled Gracefully */
161 return;
162
163 if (!user_mode(regs))
164 goto no_context;
165
166 if (fault & VM_FAULT_OOM) {
167 pagefault_out_of_memory();
168 return;
169 }
170
171 if (fault & VM_FAULT_SIGBUS) {
172 sig = SIGBUS;
173 si_code = BUS_ADRERR;
174 }
175 else {
176 sig = SIGSEGV;
177 }
178
179 tsk->thread.fault_address = address;
180 force_sig_fault(sig, si_code, (void __user *)address);
181 return;
182
183no_context:
184 if (fixup_exception(regs))
185 return;
186
187 die("Oops", regs, address);
188}
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/signal.h>
13#include <linux/errno.h>
14#include <linux/ptrace.h>
15#include <linux/uaccess.h>
16#include <linux/kdebug.h>
17#include <linux/perf_event.h>
18#include <asm/pgalloc.h>
19#include <asm/mmu.h>
20
21/*
22 * kernel virtual address is required to implement vmalloc/pkmap/fixmap
23 * Refer to asm/processor.h for System Memory Map
24 *
25 * It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
26 * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
27 */
28noinline static int handle_kernel_vaddr_fault(unsigned long address)
29{
30 /*
31 * Synchronize this task's top level page-table
32 * with the 'reference' page table.
33 */
34 pgd_t *pgd, *pgd_k;
35 pud_t *pud, *pud_k;
36 pmd_t *pmd, *pmd_k;
37
38 pgd = pgd_offset_fast(current->active_mm, address);
39 pgd_k = pgd_offset_k(address);
40
41 if (!pgd_present(*pgd_k))
42 goto bad_area;
43
44 pud = pud_offset(pgd, address);
45 pud_k = pud_offset(pgd_k, address);
46 if (!pud_present(*pud_k))
47 goto bad_area;
48
49 pmd = pmd_offset(pud, address);
50 pmd_k = pmd_offset(pud_k, address);
51 if (!pmd_present(*pmd_k))
52 goto bad_area;
53
54 set_pmd(pmd, *pmd_k);
55
56 /* XXX: create the TLB entry here */
57 return 0;
58
59bad_area:
60 return 1;
61}
62
63void do_page_fault(unsigned long address, struct pt_regs *regs)
64{
65 struct vm_area_struct *vma = NULL;
66 struct task_struct *tsk = current;
67 struct mm_struct *mm = tsk->mm;
68 siginfo_t info;
69 int fault, ret;
70 int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */
71 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
72
73 /*
74 * We fault-in kernel-space virtual memory on-demand. The
75 * 'reference' page table is init_mm.pgd.
76 *
77 * NOTE! We MUST NOT take any locks for this case. We may
78 * be in an interrupt or a critical region, and should
79 * only copy the information from the master page table,
80 * nothing more.
81 */
82 if (address >= VMALLOC_START) {
83 ret = handle_kernel_vaddr_fault(address);
84 if (unlikely(ret))
85 goto bad_area_nosemaphore;
86 else
87 return;
88 }
89
90 info.si_code = SEGV_MAPERR;
91
92 /*
93 * If we're in an interrupt or have no user
94 * context, we must not take the fault..
95 */
96 if (faulthandler_disabled() || !mm)
97 goto no_context;
98
99 if (user_mode(regs))
100 flags |= FAULT_FLAG_USER;
101retry:
102 down_read(&mm->mmap_sem);
103 vma = find_vma(mm, address);
104 if (!vma)
105 goto bad_area;
106 if (vma->vm_start <= address)
107 goto good_area;
108 if (!(vma->vm_flags & VM_GROWSDOWN))
109 goto bad_area;
110 if (expand_stack(vma, address))
111 goto bad_area;
112
113 /*
114 * Ok, we have a good vm_area for this memory access, so
115 * we can handle it..
116 */
117good_area:
118 info.si_code = SEGV_ACCERR;
119
120 /* Handle protection violation, execute on heap or stack */
121
122 if ((regs->ecr_vec == ECR_V_PROTV) &&
123 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
124 goto bad_area;
125
126 if (write) {
127 if (!(vma->vm_flags & VM_WRITE))
128 goto bad_area;
129 flags |= FAULT_FLAG_WRITE;
130 } else {
131 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
132 goto bad_area;
133 }
134
135 /*
136 * If for any reason at all we couldn't handle the fault,
137 * make sure we exit gracefully rather than endlessly redo
138 * the fault.
139 */
140 fault = handle_mm_fault(vma, address, flags);
141
142 /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
143 if (unlikely(fatal_signal_pending(current))) {
144 if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY))
145 up_read(&mm->mmap_sem);
146 if (user_mode(regs))
147 return;
148 }
149
150 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
151
152 if (likely(!(fault & VM_FAULT_ERROR))) {
153 if (flags & FAULT_FLAG_ALLOW_RETRY) {
154 /* To avoid updating stats twice for retry case */
155 if (fault & VM_FAULT_MAJOR) {
156 tsk->maj_flt++;
157 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
158 regs, address);
159 } else {
160 tsk->min_flt++;
161 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
162 regs, address);
163 }
164
165 if (fault & VM_FAULT_RETRY) {
166 flags &= ~FAULT_FLAG_ALLOW_RETRY;
167 flags |= FAULT_FLAG_TRIED;
168 goto retry;
169 }
170 }
171
172 /* Fault Handled Gracefully */
173 up_read(&mm->mmap_sem);
174 return;
175 }
176
177 if (fault & VM_FAULT_OOM)
178 goto out_of_memory;
179 else if (fault & VM_FAULT_SIGSEGV)
180 goto bad_area;
181 else if (fault & VM_FAULT_SIGBUS)
182 goto do_sigbus;
183
184 /* no man's land */
185 BUG();
186
187 /*
188 * Something tried to access memory that isn't in our memory map..
189 * Fix it, but check if it's kernel or user first..
190 */
191bad_area:
192 up_read(&mm->mmap_sem);
193
194bad_area_nosemaphore:
195 /* User mode accesses just cause a SIGSEGV */
196 if (user_mode(regs)) {
197 tsk->thread.fault_address = address;
198 info.si_signo = SIGSEGV;
199 info.si_errno = 0;
200 /* info.si_code has been set above */
201 info.si_addr = (void __user *)address;
202 force_sig_info(SIGSEGV, &info, tsk);
203 return;
204 }
205
206no_context:
207 /* Are we prepared to handle this kernel fault?
208 *
209 * (The kernel has valid exception-points in the source
210 * when it accesses user-memory. When it fails in one
211 * of those points, we find it in a table and do a jump
212 * to some fixup code that loads an appropriate error
213 * code)
214 */
215 if (fixup_exception(regs))
216 return;
217
218 die("Oops", regs, address);
219
220out_of_memory:
221 up_read(&mm->mmap_sem);
222
223 if (user_mode(regs)) {
224 pagefault_out_of_memory();
225 return;
226 }
227
228 goto no_context;
229
230do_sigbus:
231 up_read(&mm->mmap_sem);
232
233 if (!user_mode(regs))
234 goto no_context;
235
236 tsk->thread.fault_address = address;
237 info.si_signo = SIGBUS;
238 info.si_errno = 0;
239 info.si_code = BUS_ADRERR;
240 info.si_addr = (void __user *)address;
241 force_sig_info(SIGBUS, &info, tsk);
242}