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 <linux/uaccess.h>
16 #include <linux/mm.h>
17 #include <linux/sched/signal.h>
18 #include <linux/signal.h>
19 #include <linux/extable.h>
20 #include <linux/hardirq.h>
21 #include <linux/perf_event.h>
22
23 /*
24 * Decode of hardware exception sends us to one of several
25 * entry points. At each, we generate canonical arguments
26 * for handling by the abstract memory management code.
27 */
28 #define FLT_IFETCH -1
29 #define FLT_LOAD 0
30 #define FLT_STORE 1
31
32
33 /*
34 * Canonical page fault handler
35 */
do_page_fault(unsigned long address,long cause,struct pt_regs * regs)36 void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
37 {
38 struct vm_area_struct *vma;
39 struct mm_struct *mm = current->mm;
40 int si_signo;
41 int si_code = SEGV_MAPERR;
42 vm_fault_t fault;
43 const struct exception_table_entry *fixup;
44 unsigned int flags = FAULT_FLAG_DEFAULT;
45
46 /*
47 * If we're in an interrupt or have no user context,
48 * then must not take the fault.
49 */
50 if (unlikely(in_interrupt() || !mm))
51 goto no_context;
52
53 local_irq_enable();
54
55 if (user_mode(regs))
56 flags |= FAULT_FLAG_USER;
57
58 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
59 retry:
60 vma = lock_mm_and_find_vma(mm, address, regs);
61 if (unlikely(!vma))
62 goto bad_area_nosemaphore;
63
64 /* Address space is OK. Now check access rights. */
65 si_code = SEGV_ACCERR;
66
67 switch (cause) {
68 case FLT_IFETCH:
69 if (!(vma->vm_flags & VM_EXEC))
70 goto bad_area;
71 break;
72 case FLT_LOAD:
73 if (!(vma->vm_flags & VM_READ))
74 goto bad_area;
75 break;
76 case FLT_STORE:
77 if (!(vma->vm_flags & VM_WRITE))
78 goto bad_area;
79 flags |= FAULT_FLAG_WRITE;
80 break;
81 }
82
83 fault = handle_mm_fault(vma, address, flags, regs);
84
85 if (fault_signal_pending(fault, regs)) {
86 if (!user_mode(regs))
87 goto no_context;
88 return;
89 }
90
91 /* The fault is fully completed (including releasing mmap lock) */
92 if (fault & VM_FAULT_COMPLETED)
93 return;
94
95 /* The most common case -- we are done. */
96 if (likely(!(fault & VM_FAULT_ERROR))) {
97 if (fault & VM_FAULT_RETRY) {
98 flags |= FAULT_FLAG_TRIED;
99 goto retry;
100 }
101
102 mmap_read_unlock(mm);
103 return;
104 }
105
106 mmap_read_unlock(mm);
107
108 /* Handle copyin/out exception cases */
109 if (!user_mode(regs))
110 goto no_context;
111
112 if (fault & VM_FAULT_OOM) {
113 pagefault_out_of_memory();
114 return;
115 }
116
117 /* User-mode address is in the memory map, but we are
118 * unable to fix up the page fault.
119 */
120 if (fault & VM_FAULT_SIGBUS) {
121 si_signo = SIGBUS;
122 si_code = BUS_ADRERR;
123 }
124 /* Address is not in the memory map */
125 else {
126 si_signo = SIGSEGV;
127 si_code = SEGV_ACCERR;
128 }
129 force_sig_fault(si_signo, si_code, (void __user *)address);
130 return;
131
132 bad_area:
133 mmap_read_unlock(mm);
134
135 bad_area_nosemaphore:
136 if (user_mode(regs)) {
137 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
138 return;
139 }
140 /* Kernel-mode fault falls through */
141
142 no_context:
143 fixup = search_exception_tables(pt_elr(regs));
144 if (fixup) {
145 pt_set_elr(regs, fixup->fixup);
146 return;
147 }
148
149 /* Things are looking very, very bad now */
150 bust_spinlocks(1);
151 printk(KERN_EMERG "Unable to handle kernel paging request at "
152 "virtual address 0x%08lx, regs %p\n", address, regs);
153 die("Bad Kernel VA", regs, SIGKILL);
154 }
155
156
read_protection_fault(struct pt_regs * regs)157 void read_protection_fault(struct pt_regs *regs)
158 {
159 unsigned long badvadr = pt_badva(regs);
160
161 do_page_fault(badvadr, FLT_LOAD, regs);
162 }
163
write_protection_fault(struct pt_regs * regs)164 void write_protection_fault(struct pt_regs *regs)
165 {
166 unsigned long badvadr = pt_badva(regs);
167
168 do_page_fault(badvadr, FLT_STORE, regs);
169 }
170
execute_protection_fault(struct pt_regs * regs)171 void execute_protection_fault(struct pt_regs *regs)
172 {
173 unsigned long badvadr = pt_badva(regs);
174
175 do_page_fault(badvadr, FLT_IFETCH, regs);
176 }
177