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 | */ |
26 | noinline 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: *pgd_k)) |
41 | goto bad_area; |
42 | if (!pgd_present(pgd: *pgd)) |
43 | set_pgd(pgd, *pgd_k); |
44 | |
45 | p4d = p4d_offset(pgd, address); |
46 | p4d_k = p4d_offset(pgd: pgd_k, address); |
47 | if (p4d_none(p4d: *p4d_k)) |
48 | goto bad_area; |
49 | if (!p4d_present(p4d: *p4d)) |
50 | set_p4d(p4dp: p4d, p4d: *p4d_k); |
51 | |
52 | pud = pud_offset(p4d, address); |
53 | pud_k = pud_offset(p4d: p4d_k, address); |
54 | if (pud_none(pud: *pud_k)) |
55 | goto bad_area; |
56 | if (!pud_present(pud: *pud)) |
57 | set_pud(pudp: pud, pud: *pud_k); |
58 | |
59 | pmd = pmd_offset(pud, address); |
60 | pmd_k = pmd_offset(pud: pud_k, address); |
61 | if (pmd_none(pmd: *pmd_k)) |
62 | goto bad_area; |
63 | if (!pmd_present(pmd: *pmd)) |
64 | set_pmd(pmdp: pmd, pmd: *pmd_k); |
65 | |
66 | /* XXX: create the TLB entry here */ |
67 | return 0; |
68 | |
69 | bad_area: |
70 | return 1; |
71 | } |
72 | |
73 | void 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(event_id: PERF_COUNT_SW_PAGE_FAULTS, nr: 1, regs, addr: address); |
116 | retry: |
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_flags: 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 | |
156 | bad_area: |
157 | mmap_read_unlock(mm); |
158 | |
159 | bad_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, code: si_code, addr: (void __user *)address); |
186 | return; |
187 | |
188 | no_context: |
189 | if (fixup_exception(regs)) |
190 | return; |
191 | |
192 | die("Oops" , regs, address); |
193 | } |
194 | |