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 | */ |
37 | static 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(event_id: PERF_COUNT_SW_PAGE_FAULTS, nr: 1, regs, addr: address); |
60 | retry: |
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_flags: 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(sig: si_signo, code: si_code, addr: (void __user *)address); |
131 | return; |
132 | |
133 | bad_area: |
134 | mmap_read_unlock(mm); |
135 | |
136 | bad_area_nosemaphore: |
137 | if (user_mode(regs)) { |
138 | force_sig_fault(SIGSEGV, code: si_code, addr: (void __user *)address); |
139 | return; |
140 | } |
141 | /* Kernel-mode fault falls through */ |
142 | |
143 | no_context: |
144 | fixup = search_exception_tables(add: 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(yes: 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 | |
158 | void read_protection_fault(struct pt_regs *regs) |
159 | { |
160 | unsigned long badvadr = pt_badva(regs); |
161 | |
162 | do_page_fault(address: badvadr, FLT_LOAD, regs); |
163 | } |
164 | |
165 | void write_protection_fault(struct pt_regs *regs) |
166 | { |
167 | unsigned long badvadr = pt_badva(regs); |
168 | |
169 | do_page_fault(address: badvadr, FLT_STORE, regs); |
170 | } |
171 | |
172 | void execute_protection_fault(struct pt_regs *regs) |
173 | { |
174 | unsigned long badvadr = pt_badva(regs); |
175 | |
176 | do_page_fault(address: badvadr, FLT_IFETCH, regs); |
177 | } |
178 | |