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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/pgalloc.h>
17#include <asm/mmu.h>
18
19/*
20 * kernel virtual address is required to implement vmalloc/pkmap/fixmap
21 * Refer to asm/processor.h for System Memory Map
22 *
23 * It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
24 * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
25 */
26noinline static int handle_kernel_vaddr_fault(unsigned long address)
27{
28 /*
29 * Synchronize this task's top level page-table
30 * with the 'reference' page table.
31 */
32 pgd_t *pgd, *pgd_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 pud = pud_offset(pgd, address);
43 pud_k = pud_offset(pgd_k, address);
44 if (!pud_present(*pud_k))
45 goto bad_area;
46
47 pmd = pmd_offset(pud, address);
48 pmd_k = pmd_offset(pud_k, address);
49 if (!pmd_present(*pmd_k))
50 goto bad_area;
51
52 set_pmd(pmd, *pmd_k);
53
54 /* XXX: create the TLB entry here */
55 return 0;
56
57bad_area:
58 return 1;
59}
60
61void do_page_fault(unsigned long address, struct pt_regs *regs)
62{
63 struct vm_area_struct *vma = NULL;
64 struct task_struct *tsk = current;
65 struct mm_struct *mm = tsk->mm;
66 int sig, si_code = SEGV_MAPERR;
67 unsigned int write = 0, exec = 0, mask;
68 vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */
69 unsigned int flags; /* handle_mm_fault() input */
70
71 /*
72 * NOTE! We MUST NOT take any locks for this case. We may
73 * be in an interrupt or a critical region, and should
74 * only copy the information from the master page table,
75 * nothing more.
76 */
77 if (address >= VMALLOC_START && !user_mode(regs)) {
78 if (unlikely(handle_kernel_vaddr_fault(address)))
79 goto no_context;
80 else
81 return;
82 }
83
84 /*
85 * If we're in an interrupt or have no user
86 * context, we must not take the fault..
87 */
88 if (faulthandler_disabled() || !mm)
89 goto no_context;
90
91 if (regs->ecr_cause & ECR_C_PROTV_STORE) /* ST/EX */
92 write = 1;
93 else if ((regs->ecr_vec == ECR_V_PROTV) &&
94 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
95 exec = 1;
96
97 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
98 if (user_mode(regs))
99 flags |= FAULT_FLAG_USER;
100 if (write)
101 flags |= FAULT_FLAG_WRITE;
102
103retry:
104 down_read(&mm->mmap_sem);
105
106 vma = find_vma(mm, address);
107 if (!vma)
108 goto bad_area;
109 if (unlikely(address < vma->vm_start)) {
110 if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, address))
111 goto bad_area;
112 }
113
114 /*
115 * vm_area is good, now check permissions for this memory access
116 */
117 mask = VM_READ;
118 if (write)
119 mask = VM_WRITE;
120 if (exec)
121 mask = VM_EXEC;
122
123 if (!(vma->vm_flags & mask)) {
124 si_code = SEGV_ACCERR;
125 goto bad_area;
126 }
127
128 fault = handle_mm_fault(vma, address, flags);
129
130 /*
131 * Fault retry nuances
132 */
133 if (unlikely(fault & VM_FAULT_RETRY)) {
134
135 /*
136 * If fault needs to be retried, handle any pending signals
137 * first (by returning to user mode).
138 * mmap_sem already relinquished by core mm for RETRY case
139 */
140 if (fatal_signal_pending(current)) {
141 if (!user_mode(regs))
142 goto no_context;
143 return;
144 }
145 /*
146 * retry state machine
147 */
148 if (flags & FAULT_FLAG_ALLOW_RETRY) {
149 flags &= ~FAULT_FLAG_ALLOW_RETRY;
150 flags |= FAULT_FLAG_TRIED;
151 goto retry;
152 }
153 }
154
155bad_area:
156 up_read(&mm->mmap_sem);
157
158 /*
159 * Major/minor page fault accounting
160 * (in case of retry we only land here once)
161 */
162 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
163
164 if (likely(!(fault & VM_FAULT_ERROR))) {
165 if (fault & VM_FAULT_MAJOR) {
166 tsk->maj_flt++;
167 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
168 regs, address);
169 } else {
170 tsk->min_flt++;
171 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
172 regs, address);
173 }
174
175 /* Normal return path: fault Handled Gracefully */
176 return;
177 }
178
179 if (!user_mode(regs))
180 goto no_context;
181
182 if (fault & VM_FAULT_OOM) {
183 pagefault_out_of_memory();
184 return;
185 }
186
187 if (fault & VM_FAULT_SIGBUS) {
188 sig = SIGBUS;
189 si_code = BUS_ADRERR;
190 }
191 else {
192 sig = SIGSEGV;
193 }
194
195 tsk->thread.fault_address = address;
196 force_sig_fault(sig, si_code, (void __user *)address);
197 return;
198
199no_context:
200 if (fixup_exception(regs))
201 return;
202
203 die("Oops", regs, address);
204}
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/entry.h>
17#include <asm/mmu.h>
18
19/*
20 * kernel virtual address is required to implement vmalloc/pkmap/fixmap
21 * Refer to asm/processor.h for System Memory Map
22 *
23 * It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
24 * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
25 */
26noinline static int handle_kernel_vaddr_fault(unsigned long address)
27{
28 /*
29 * Synchronize this task's top level page-table
30 * with the 'reference' page table.
31 */
32 pgd_t *pgd, *pgd_k;
33 p4d_t *p4d, *p4d_k;
34 pud_t *pud, *pud_k;
35 pmd_t *pmd, *pmd_k;
36
37 pgd = pgd_offset(current->active_mm, address);
38 pgd_k = pgd_offset_k(address);
39
40 if (pgd_none (*pgd_k))
41 goto bad_area;
42 if (!pgd_present(*pgd))
43 set_pgd(pgd, *pgd_k);
44
45 p4d = p4d_offset(pgd, address);
46 p4d_k = p4d_offset(pgd_k, address);
47 if (p4d_none(*p4d_k))
48 goto bad_area;
49 if (!p4d_present(*p4d))
50 set_p4d(p4d, *p4d_k);
51
52 pud = pud_offset(p4d, address);
53 pud_k = pud_offset(p4d_k, address);
54 if (pud_none(*pud_k))
55 goto bad_area;
56 if (!pud_present(*pud))
57 set_pud(pud, *pud_k);
58
59 pmd = pmd_offset(pud, address);
60 pmd_k = pmd_offset(pud_k, address);
61 if (pmd_none(*pmd_k))
62 goto bad_area;
63 if (!pmd_present(*pmd))
64 set_pmd(pmd, *pmd_k);
65
66 /* XXX: create the TLB entry here */
67 return 0;
68
69bad_area:
70 return 1;
71}
72
73void do_page_fault(unsigned long address, struct pt_regs *regs)
74{
75 struct vm_area_struct *vma = NULL;
76 struct task_struct *tsk = current;
77 struct mm_struct *mm = tsk->mm;
78 int sig, si_code = SEGV_MAPERR;
79 unsigned int write = 0, exec = 0, mask;
80 vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */
81 unsigned int flags; /* handle_mm_fault() input */
82
83 /*
84 * NOTE! We MUST NOT take any locks for this case. We may
85 * be in an interrupt or a critical region, and should
86 * only copy the information from the master page table,
87 * nothing more.
88 */
89 if (address >= VMALLOC_START && !user_mode(regs)) {
90 if (unlikely(handle_kernel_vaddr_fault(address)))
91 goto no_context;
92 else
93 return;
94 }
95
96 /*
97 * If we're in an interrupt or have no user
98 * context, we must not take the fault..
99 */
100 if (faulthandler_disabled() || !mm)
101 goto no_context;
102
103 if (regs->ecr.cause & ECR_C_PROTV_STORE) /* ST/EX */
104 write = 1;
105 else if ((regs->ecr.vec == ECR_V_PROTV) &&
106 (regs->ecr.cause == ECR_C_PROTV_INST_FETCH))
107 exec = 1;
108
109 flags = FAULT_FLAG_DEFAULT;
110 if (user_mode(regs))
111 flags |= FAULT_FLAG_USER;
112 if (write)
113 flags |= FAULT_FLAG_WRITE;
114
115 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
116retry:
117 vma = lock_mm_and_find_vma(mm, address, regs);
118 if (!vma)
119 goto bad_area_nosemaphore;
120
121 /*
122 * vm_area is good, now check permissions for this memory access
123 */
124 mask = VM_READ;
125 if (write)
126 mask = VM_WRITE;
127 if (exec)
128 mask = VM_EXEC;
129
130 if (!(vma->vm_flags & mask)) {
131 si_code = SEGV_ACCERR;
132 goto bad_area;
133 }
134
135 fault = handle_mm_fault(vma, address, flags, regs);
136
137 /* Quick path to respond to signals */
138 if (fault_signal_pending(fault, regs)) {
139 if (!user_mode(regs))
140 goto no_context;
141 return;
142 }
143
144 /* The fault is fully completed (including releasing mmap lock) */
145 if (fault & VM_FAULT_COMPLETED)
146 return;
147
148 /*
149 * Fault retry nuances, mmap_lock already relinquished by core mm
150 */
151 if (unlikely(fault & VM_FAULT_RETRY)) {
152 flags |= FAULT_FLAG_TRIED;
153 goto retry;
154 }
155
156bad_area:
157 mmap_read_unlock(mm);
158
159bad_area_nosemaphore:
160 /*
161 * Major/minor page fault accounting
162 * (in case of retry we only land here once)
163 */
164 if (likely(!(fault & VM_FAULT_ERROR)))
165 /* Normal return path: fault Handled Gracefully */
166 return;
167
168 if (!user_mode(regs))
169 goto no_context;
170
171 if (fault & VM_FAULT_OOM) {
172 pagefault_out_of_memory();
173 return;
174 }
175
176 if (fault & VM_FAULT_SIGBUS) {
177 sig = SIGBUS;
178 si_code = BUS_ADRERR;
179 }
180 else {
181 sig = SIGSEGV;
182 }
183
184 tsk->thread.fault_address = address;
185 force_sig_fault(sig, si_code, (void __user *)address);
186 return;
187
188no_context:
189 if (fixup_exception(regs))
190 return;
191
192 die("Oops", regs, address);
193}