1 /*
2 * Memory fault handling for Hexagon
3 *
4 * Copyright (c) 2010-2011 Code Aurora Forum. All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 and
8 * only version 2 as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
18 * 02110-1301, USA.
19 */
20
21 /*
22 * Page fault handling for the Hexagon Virtual Machine.
23 * Can also be called by a native port emulating the HVM
24 * execptions.
25 */
26
27 #include <asm/pgtable.h>
28 #include <asm/traps.h>
29 #include <asm/uaccess.h>
30 #include <linux/mm.h>
31 #include <linux/signal.h>
32 #include <linux/module.h>
33 #include <linux/hardirq.h>
34
35 /*
36 * Decode of hardware exception sends us to one of several
37 * entry points. At each, we generate canonical arguments
38 * for handling by the abstract memory management code.
39 */
40 #define FLT_IFETCH -1
41 #define FLT_LOAD 0
42 #define FLT_STORE 1
43
44
45 /*
46 * Canonical page fault handler
47 */
do_page_fault(unsigned long address,long cause,struct pt_regs * regs)48 void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
49 {
50 struct vm_area_struct *vma;
51 struct mm_struct *mm = current->mm;
52 siginfo_t info;
53 int si_code = SEGV_MAPERR;
54 int fault;
55 const struct exception_table_entry *fixup;
56
57 /*
58 * If we're in an interrupt or have no user context,
59 * then must not take the fault.
60 */
61 if (unlikely(in_interrupt() || !mm))
62 goto no_context;
63
64 local_irq_enable();
65
66 down_read(&mm->mmap_sem);
67 vma = find_vma(mm, address);
68 if (!vma)
69 goto bad_area;
70
71 if (vma->vm_start <= address)
72 goto good_area;
73
74 if (!(vma->vm_flags & VM_GROWSDOWN))
75 goto bad_area;
76
77 if (expand_stack(vma, address))
78 goto bad_area;
79
80 good_area:
81 /* Address space is OK. Now check access rights. */
82 si_code = SEGV_ACCERR;
83
84 switch (cause) {
85 case FLT_IFETCH:
86 if (!(vma->vm_flags & VM_EXEC))
87 goto bad_area;
88 break;
89 case FLT_LOAD:
90 if (!(vma->vm_flags & VM_READ))
91 goto bad_area;
92 break;
93 case FLT_STORE:
94 if (!(vma->vm_flags & VM_WRITE))
95 goto bad_area;
96 break;
97 }
98
99 fault = handle_mm_fault(mm, vma, address, (cause > 0));
100
101 /* The most common case -- we are done. */
102 if (likely(!(fault & VM_FAULT_ERROR))) {
103 if (fault & VM_FAULT_MAJOR)
104 current->maj_flt++;
105 else
106 current->min_flt++;
107
108 up_read(&mm->mmap_sem);
109 return;
110 }
111
112 up_read(&mm->mmap_sem);
113
114 /* Handle copyin/out exception cases */
115 if (!user_mode(regs))
116 goto no_context;
117
118 if (fault & VM_FAULT_OOM) {
119 pagefault_out_of_memory();
120 return;
121 }
122
123 /* User-mode address is in the memory map, but we are
124 * unable to fix up the page fault.
125 */
126 if (fault & VM_FAULT_SIGBUS) {
127 info.si_signo = SIGBUS;
128 info.si_code = BUS_ADRERR;
129 }
130 /* Address is not in the memory map */
131 else {
132 info.si_signo = SIGSEGV;
133 info.si_code = SEGV_ACCERR;
134 }
135 info.si_errno = 0;
136 info.si_addr = (void __user *)address;
137 force_sig_info(info.si_code, &info, current);
138 return;
139
140 bad_area:
141 up_read(&mm->mmap_sem);
142
143 if (user_mode(regs)) {
144 info.si_signo = SIGSEGV;
145 info.si_errno = 0;
146 info.si_code = si_code;
147 info.si_addr = (void *)address;
148 force_sig_info(SIGSEGV, &info, current);
149 return;
150 }
151 /* Kernel-mode fault falls through */
152
153 no_context:
154 fixup = search_exception_tables(pt_elr(regs));
155 if (fixup) {
156 pt_set_elr(regs, fixup->fixup);
157 return;
158 }
159
160 /* Things are looking very, very bad now */
161 bust_spinlocks(1);
162 printk(KERN_EMERG "Unable to handle kernel paging request at "
163 "virtual address 0x%08lx, regs %p\n", address, regs);
164 die("Bad Kernel VA", regs, SIGKILL);
165 }
166
167
read_protection_fault(struct pt_regs * regs)168 void read_protection_fault(struct pt_regs *regs)
169 {
170 unsigned long badvadr = pt_badva(regs);
171
172 do_page_fault(badvadr, FLT_LOAD, regs);
173 }
174
write_protection_fault(struct pt_regs * regs)175 void write_protection_fault(struct pt_regs *regs)
176 {
177 unsigned long badvadr = pt_badva(regs);
178
179 do_page_fault(badvadr, FLT_STORE, regs);
180 }
181
execute_protection_fault(struct pt_regs * regs)182 void execute_protection_fault(struct pt_regs *regs)
183 {
184 unsigned long badvadr = pt_badva(regs);
185
186 do_page_fault(badvadr, FLT_IFETCH, regs);
187 }
188