blob: 2bd7487440c455802dac6470ec05ac138148bfcb [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/arch/m68k/mm/fault.c
3 *
4 * Copyright (C) 1995 Hamish Macdonald
5 */
6
7#include <linux/mman.h>
8#include <linux/mm.h>
9#include <linux/kernel.h>
10#include <linux/ptrace.h>
11#include <linux/interrupt.h>
12#include <linux/module.h>
13
14#include <asm/setup.h>
15#include <asm/traps.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <asm/uaccess.h>
17#include <asm/pgalloc.h>
18
19extern void die_if_kernel(char *, struct pt_regs *, long);
Linus Torvalds1da177e2005-04-16 15:20:36 -070020
21int send_fault_sig(struct pt_regs *regs)
22{
23 siginfo_t siginfo = { 0, 0, 0, };
24
25 siginfo.si_signo = current->thread.signo;
26 siginfo.si_code = current->thread.code;
27 siginfo.si_addr = (void *)current->thread.faddr;
Geert Uytterhoeven8e398f62013-12-10 12:04:16 +010028 pr_debug("send_fault_sig: %p,%d,%d\n", siginfo.si_addr,
29 siginfo.si_signo, siginfo.si_code);
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
31 if (user_mode(regs)) {
32 force_sig_info(siginfo.si_signo,
33 &siginfo, current);
34 } else {
Roman Zippeldcdf3a22008-11-18 21:25:17 +010035 if (handle_kernel_fault(regs))
Linus Torvalds1da177e2005-04-16 15:20:36 -070036 return -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 //if (siginfo.si_signo == SIGBUS)
39 // force_sig_info(siginfo.si_signo,
40 // &siginfo, current);
41
42 /*
43 * Oops. The kernel tried to access some bad page. We'll have to
44 * terminate things with extreme prejudice.
45 */
46 if ((unsigned long)siginfo.si_addr < PAGE_SIZE)
Geert Uytterhoeven8e398f62013-12-10 12:04:16 +010047 pr_alert("Unable to handle kernel NULL pointer dereference");
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 else
Geert Uytterhoeven8e398f62013-12-10 12:04:16 +010049 pr_alert("Unable to handle kernel access");
50 pr_cont(" at virtual address %p\n", siginfo.si_addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 die_if_kernel("Oops", regs, 0 /*error_code*/);
52 do_exit(SIGKILL);
53 }
54
55 return 1;
56}
57
58/*
59 * This routine handles page faults. It determines the problem, and
60 * then passes it off to one of the appropriate routines.
61 *
62 * error_code:
63 * bit 0 == 0 means no page found, 1 means protection fault
64 * bit 1 == 0 means read, 1 means write
65 *
66 * If this routine detects a bad access, it returns 1, otherwise it
67 * returns 0.
68 */
69int do_page_fault(struct pt_regs *regs, unsigned long address,
70 unsigned long error_code)
71{
72 struct mm_struct *mm = current->mm;
73 struct vm_area_struct * vma;
Kautuk Consulb637a6b2012-03-25 06:37:48 -040074 int fault;
75 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
Linus Torvalds1da177e2005-04-16 15:20:36 -070076
Geert Uytterhoeven8e398f62013-12-10 12:04:16 +010077 pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
Geert Uytterhoeven4e25c0e2013-12-10 11:35:47 +010078 regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -070079
80 /*
81 * If we're in an interrupt or have no user
82 * context, we must not take the fault..
83 */
Peter Zijlstra6edaf682006-12-06 20:32:18 -080084 if (in_atomic() || !mm)
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 goto no_context;
86
Johannes Weiner759496b2013-09-12 15:13:39 -070087 if (user_mode(regs))
88 flags |= FAULT_FLAG_USER;
Kautuk Consulb637a6b2012-03-25 06:37:48 -040089retry:
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 down_read(&mm->mmap_sem);
91
92 vma = find_vma(mm, address);
93 if (!vma)
94 goto map_err;
95 if (vma->vm_flags & VM_IO)
96 goto acc_err;
97 if (vma->vm_start <= address)
98 goto good_area;
99 if (!(vma->vm_flags & VM_GROWSDOWN))
100 goto map_err;
101 if (user_mode(regs)) {
102 /* Accessing the stack below usp is always a bug. The
103 "+ 256" is there due to some instructions doing
104 pre-decrement on the stack and that doesn't show up
105 until later. */
106 if (address + 256 < rdusp())
107 goto map_err;
108 }
109 if (expand_stack(vma, address))
110 goto map_err;
111
112/*
113 * Ok, we have a good vm_area for this memory access, so
114 * we can handle it..
115 */
116good_area:
Geert Uytterhoeven8e398f62013-12-10 12:04:16 +0100117 pr_debug("do_page_fault: good_area\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 switch (error_code & 3) {
119 default: /* 3: write, present */
120 /* fall through */
121 case 2: /* write, not present */
122 if (!(vma->vm_flags & VM_WRITE))
123 goto acc_err;
Kautuk Consulb637a6b2012-03-25 06:37:48 -0400124 flags |= FAULT_FLAG_WRITE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 break;
126 case 1: /* read, present */
127 goto acc_err;
128 case 0: /* read, not present */
Jason Barondf67b3d2006-09-29 01:58:58 -0700129 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 goto acc_err;
131 }
132
133 /*
134 * If for any reason at all we couldn't handle the fault,
135 * make sure we exit gracefully rather than endlessly redo
136 * the fault.
137 */
138
Kautuk Consulb637a6b2012-03-25 06:37:48 -0400139 fault = handle_mm_fault(mm, vma, address, flags);
Geert Uytterhoeven8e398f62013-12-10 12:04:16 +0100140 pr_debug("handle_mm_fault returns %d\n", fault);
Kautuk Consulb637a6b2012-03-25 06:37:48 -0400141
142 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
143 return 0;
144
Nick Piggin83c54072007-07-19 01:47:05 -0700145 if (unlikely(fault & VM_FAULT_ERROR)) {
146 if (fault & VM_FAULT_OOM)
147 goto out_of_memory;
148 else if (fault & VM_FAULT_SIGBUS)
149 goto bus_err;
150 BUG();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 }
Kautuk Consulb637a6b2012-03-25 06:37:48 -0400152
153 /*
154 * Major/minor page fault accounting is only done on the
155 * initial attempt. If we go through a retry, it is extremely
156 * likely that the page will be found in page cache at that point.
157 */
158 if (flags & FAULT_FLAG_ALLOW_RETRY) {
159 if (fault & VM_FAULT_MAJOR)
160 current->maj_flt++;
161 else
162 current->min_flt++;
163 if (fault & VM_FAULT_RETRY) {
164 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
165 * of starvation. */
166 flags &= ~FAULT_FLAG_ALLOW_RETRY;
Shaohua Li45cac652012-10-08 16:32:19 -0700167 flags |= FAULT_FLAG_TRIED;
Kautuk Consulb637a6b2012-03-25 06:37:48 -0400168
169 /*
170 * No need to up_read(&mm->mmap_sem) as we would
171 * have already released it in __lock_page_or_retry
172 * in mm/filemap.c.
173 */
174
175 goto retry;
176 }
177 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178
179 up_read(&mm->mmap_sem);
180 return 0;
181
182/*
183 * We ran out of memory, or some other thing happened to us that made
184 * us unable to handle the page fault gracefully.
185 */
186out_of_memory:
187 up_read(&mm->mmap_sem);
Nick Pigginadbf6e62010-04-23 02:06:20 +1000188 if (!user_mode(regs))
189 goto no_context;
190 pagefault_out_of_memory();
191 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192
193no_context:
194 current->thread.signo = SIGBUS;
195 current->thread.faddr = address;
196 return send_fault_sig(regs);
197
198bus_err:
199 current->thread.signo = SIGBUS;
200 current->thread.code = BUS_ADRERR;
201 current->thread.faddr = address;
202 goto send_sig;
203
204map_err:
205 current->thread.signo = SIGSEGV;
206 current->thread.code = SEGV_MAPERR;
207 current->thread.faddr = address;
208 goto send_sig;
209
210acc_err:
211 current->thread.signo = SIGSEGV;
212 current->thread.code = SEGV_ACCERR;
213 current->thread.faddr = address;
214
215send_sig:
216 up_read(&mm->mmap_sem);
217 return send_fault_sig(regs);
218}