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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/arch/m68k/mm/fault.c
4 *
5 * Copyright (C) 1995 Hamish Macdonald
6 */
7
8#include <linux/mman.h>
9#include <linux/mm.h>
10#include <linux/kernel.h>
11#include <linux/ptrace.h>
12#include <linux/interrupt.h>
13#include <linux/module.h>
14#include <linux/uaccess.h>
15
16#include <asm/setup.h>
17#include <asm/traps.h>
18#include <asm/pgalloc.h>
19
20extern void die_if_kernel(char *, struct pt_regs *, long);
21
22int send_fault_sig(struct pt_regs *regs)
23{
24 siginfo_t siginfo;
25
26 clear_siginfo(&siginfo);
27 siginfo.si_signo = current->thread.signo;
28 siginfo.si_code = current->thread.code;
29 siginfo.si_addr = (void *)current->thread.faddr;
30 pr_debug("send_fault_sig: %p,%d,%d\n", siginfo.si_addr,
31 siginfo.si_signo, siginfo.si_code);
32
33 if (user_mode(regs)) {
34 force_sig_info(siginfo.si_signo,
35 &siginfo, current);
36 } else {
37 if (fixup_exception(regs))
38 return -1;
39
40 //if (siginfo.si_signo == SIGBUS)
41 // force_sig_info(siginfo.si_signo,
42 // &siginfo, current);
43
44 /*
45 * Oops. The kernel tried to access some bad page. We'll have to
46 * terminate things with extreme prejudice.
47 */
48 if ((unsigned long)siginfo.si_addr < PAGE_SIZE)
49 pr_alert("Unable to handle kernel NULL pointer dereference");
50 else
51 pr_alert("Unable to handle kernel access");
52 pr_cont(" at virtual address %p\n", siginfo.si_addr);
53 die_if_kernel("Oops", regs, 0 /*error_code*/);
54 do_exit(SIGKILL);
55 }
56
57 return 1;
58}
59
60/*
61 * This routine handles page faults. It determines the problem, and
62 * then passes it off to one of the appropriate routines.
63 *
64 * error_code:
65 * bit 0 == 0 means no page found, 1 means protection fault
66 * bit 1 == 0 means read, 1 means write
67 *
68 * If this routine detects a bad access, it returns 1, otherwise it
69 * returns 0.
70 */
71int do_page_fault(struct pt_regs *regs, unsigned long address,
72 unsigned long error_code)
73{
74 struct mm_struct *mm = current->mm;
75 struct vm_area_struct * vma;
76 int fault;
77 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
78
79 pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
80 regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);
81
82 /*
83 * If we're in an interrupt or have no user
84 * context, we must not take the fault..
85 */
86 if (faulthandler_disabled() || !mm)
87 goto no_context;
88
89 if (user_mode(regs))
90 flags |= FAULT_FLAG_USER;
91retry:
92 down_read(&mm->mmap_sem);
93
94 vma = find_vma(mm, address);
95 if (!vma)
96 goto map_err;
97 if (vma->vm_flags & VM_IO)
98 goto acc_err;
99 if (vma->vm_start <= address)
100 goto good_area;
101 if (!(vma->vm_flags & VM_GROWSDOWN))
102 goto map_err;
103 if (user_mode(regs)) {
104 /* Accessing the stack below usp is always a bug. The
105 "+ 256" is there due to some instructions doing
106 pre-decrement on the stack and that doesn't show up
107 until later. */
108 if (address + 256 < rdusp())
109 goto map_err;
110 }
111 if (expand_stack(vma, address))
112 goto map_err;
113
114/*
115 * Ok, we have a good vm_area for this memory access, so
116 * we can handle it..
117 */
118good_area:
119 pr_debug("do_page_fault: good_area\n");
120 switch (error_code & 3) {
121 default: /* 3: write, present */
122 /* fall through */
123 case 2: /* write, not present */
124 if (!(vma->vm_flags & VM_WRITE))
125 goto acc_err;
126 flags |= FAULT_FLAG_WRITE;
127 break;
128 case 1: /* read, present */
129 goto acc_err;
130 case 0: /* read, not present */
131 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
132 goto acc_err;
133 }
134
135 /*
136 * If for any reason at all we couldn't handle the fault,
137 * make sure we exit gracefully rather than endlessly redo
138 * the fault.
139 */
140
141 fault = handle_mm_fault(vma, address, flags);
142 pr_debug("handle_mm_fault returns %d\n", fault);
143
144 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
145 return 0;
146
147 if (unlikely(fault & VM_FAULT_ERROR)) {
148 if (fault & VM_FAULT_OOM)
149 goto out_of_memory;
150 else if (fault & VM_FAULT_SIGSEGV)
151 goto map_err;
152 else if (fault & VM_FAULT_SIGBUS)
153 goto bus_err;
154 BUG();
155 }
156
157 /*
158 * Major/minor page fault accounting is only done on the
159 * initial attempt. If we go through a retry, it is extremely
160 * likely that the page will be found in page cache at that point.
161 */
162 if (flags & FAULT_FLAG_ALLOW_RETRY) {
163 if (fault & VM_FAULT_MAJOR)
164 current->maj_flt++;
165 else
166 current->min_flt++;
167 if (fault & VM_FAULT_RETRY) {
168 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
169 * of starvation. */
170 flags &= ~FAULT_FLAG_ALLOW_RETRY;
171 flags |= FAULT_FLAG_TRIED;
172
173 /*
174 * No need to up_read(&mm->mmap_sem) as we would
175 * have already released it in __lock_page_or_retry
176 * in mm/filemap.c.
177 */
178
179 goto retry;
180 }
181 }
182
183 up_read(&mm->mmap_sem);
184 return 0;
185
186/*
187 * We ran out of memory, or some other thing happened to us that made
188 * us unable to handle the page fault gracefully.
189 */
190out_of_memory:
191 up_read(&mm->mmap_sem);
192 if (!user_mode(regs))
193 goto no_context;
194 pagefault_out_of_memory();
195 return 0;
196
197no_context:
198 current->thread.signo = SIGBUS;
199 current->thread.faddr = address;
200 return send_fault_sig(regs);
201
202bus_err:
203 current->thread.signo = SIGBUS;
204 current->thread.code = BUS_ADRERR;
205 current->thread.faddr = address;
206 goto send_sig;
207
208map_err:
209 current->thread.signo = SIGSEGV;
210 current->thread.code = SEGV_MAPERR;
211 current->thread.faddr = address;
212 goto send_sig;
213
214acc_err:
215 current->thread.signo = SIGSEGV;
216 current->thread.code = SEGV_ACCERR;
217 current->thread.faddr = address;
218
219send_sig:
220 up_read(&mm->mmap_sem);
221 return send_fault_sig(regs);
222}
1/*
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>
16#include <asm/uaccess.h>
17#include <asm/pgalloc.h>
18
19extern void die_if_kernel(char *, struct pt_regs *, long);
20
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;
28 pr_debug("send_fault_sig: %p,%d,%d\n", siginfo.si_addr,
29 siginfo.si_signo, siginfo.si_code);
30
31 if (user_mode(regs)) {
32 force_sig_info(siginfo.si_signo,
33 &siginfo, current);
34 } else {
35 if (handle_kernel_fault(regs))
36 return -1;
37
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)
47 pr_alert("Unable to handle kernel NULL pointer dereference");
48 else
49 pr_alert("Unable to handle kernel access");
50 pr_cont(" at virtual address %p\n", siginfo.si_addr);
51 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;
74 int fault;
75 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
76
77 pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
78 regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);
79
80 /*
81 * If we're in an interrupt or have no user
82 * context, we must not take the fault..
83 */
84 if (in_atomic() || !mm)
85 goto no_context;
86
87 if (user_mode(regs))
88 flags |= FAULT_FLAG_USER;
89retry:
90 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:
117 pr_debug("do_page_fault: good_area\n");
118 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;
124 flags |= FAULT_FLAG_WRITE;
125 break;
126 case 1: /* read, present */
127 goto acc_err;
128 case 0: /* read, not present */
129 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
130 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
139 fault = handle_mm_fault(mm, vma, address, flags);
140 pr_debug("handle_mm_fault returns %d\n", fault);
141
142 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
143 return 0;
144
145 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();
151 }
152
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;
167 flags |= FAULT_FLAG_TRIED;
168
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 }
178
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);
188 if (!user_mode(regs))
189 goto no_context;
190 pagefault_out_of_memory();
191 return 0;
192
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}