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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#include <linux/perf_event.h>
16
17#include <asm/setup.h>
18#include <asm/traps.h>
19
20#include "fault.h"
21
22extern void die_if_kernel(char *, struct pt_regs *, long);
23
24int send_fault_sig(struct pt_regs *regs)
25{
26 int signo, si_code;
27 void __user *addr;
28
29 signo = current->thread.signo;
30 si_code = current->thread.code;
31 addr = (void __user *)current->thread.faddr;
32 pr_debug("send_fault_sig: %p,%d,%d\n", addr, signo, si_code);
33
34 if (user_mode(regs)) {
35 force_sig_fault(signo, si_code, addr);
36 } else {
37 if (fixup_exception(regs))
38 return -1;
39
40 //if (signo == SIGBUS)
41 // force_sig_fault(si_signo, si_code, addr);
42
43 /*
44 * Oops. The kernel tried to access some bad page. We'll have to
45 * terminate things with extreme prejudice.
46 */
47 if ((unsigned long)addr < PAGE_SIZE)
48 pr_alert("Unable to handle kernel NULL pointer dereference");
49 else
50 pr_alert("Unable to handle kernel access");
51 pr_cont(" at virtual address %p\n", addr);
52 die_if_kernel("Oops", regs, 0 /*error_code*/);
53 make_task_dead(SIGKILL);
54 }
55
56 return 1;
57}
58
59/*
60 * This routine handles page faults. It determines the problem, and
61 * then passes it off to one of the appropriate routines.
62 *
63 * error_code:
64 * bit 0 == 0 means no page found, 1 means protection fault
65 * bit 1 == 0 means read, 1 means write
66 *
67 * If this routine detects a bad access, it returns 1, otherwise it
68 * returns 0.
69 */
70int do_page_fault(struct pt_regs *regs, unsigned long address,
71 unsigned long error_code)
72{
73 struct mm_struct *mm = current->mm;
74 struct vm_area_struct * vma;
75 vm_fault_t fault;
76 unsigned int flags = FAULT_FLAG_DEFAULT;
77
78 pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
79 regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);
80
81 /*
82 * If we're in an interrupt or have no user
83 * context, we must not take the fault..
84 */
85 if (faulthandler_disabled() || !mm)
86 goto no_context;
87
88 if (user_mode(regs))
89 flags |= FAULT_FLAG_USER;
90
91 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
92retry:
93 mmap_read_lock(mm);
94
95 vma = find_vma(mm, address);
96 if (!vma)
97 goto map_err;
98 if (vma->vm_start <= address)
99 goto good_area;
100 if (!(vma->vm_flags & VM_GROWSDOWN))
101 goto map_err;
102 if (user_mode(regs)) {
103 /* Accessing the stack below usp is always a bug. The
104 "+ 256" is there due to some instructions doing
105 pre-decrement on the stack and that doesn't show up
106 until later. */
107 if (address + 256 < rdusp())
108 goto map_err;
109 }
110 vma = expand_stack(mm, address);
111 if (!vma)
112 goto map_err_nosemaphore;
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 fallthrough;
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 (unlikely(!vma_is_accessible(vma)))
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, regs);
142 pr_debug("handle_mm_fault returns %x\n", fault);
143
144 if (fault_signal_pending(fault, regs)) {
145 if (!user_mode(regs))
146 goto no_context;
147 return 0;
148 }
149
150 /* The fault is fully completed (including releasing mmap lock) */
151 if (fault & VM_FAULT_COMPLETED)
152 return 0;
153
154 if (unlikely(fault & VM_FAULT_ERROR)) {
155 if (fault & VM_FAULT_OOM)
156 goto out_of_memory;
157 else if (fault & VM_FAULT_SIGSEGV)
158 goto map_err;
159 else if (fault & VM_FAULT_SIGBUS)
160 goto bus_err;
161 BUG();
162 }
163
164 if (fault & VM_FAULT_RETRY) {
165 flags |= FAULT_FLAG_TRIED;
166
167 /*
168 * No need to mmap_read_unlock(mm) as we would
169 * have already released it in __lock_page_or_retry
170 * in mm/filemap.c.
171 */
172
173 goto retry;
174 }
175
176 mmap_read_unlock(mm);
177 return 0;
178
179/*
180 * We ran out of memory, or some other thing happened to us that made
181 * us unable to handle the page fault gracefully.
182 */
183out_of_memory:
184 mmap_read_unlock(mm);
185 if (!user_mode(regs))
186 goto no_context;
187 pagefault_out_of_memory();
188 return 0;
189
190no_context:
191 current->thread.signo = SIGBUS;
192 current->thread.faddr = address;
193 return send_fault_sig(regs);
194
195bus_err:
196 current->thread.signo = SIGBUS;
197 current->thread.code = BUS_ADRERR;
198 current->thread.faddr = address;
199 goto send_sig;
200
201map_err:
202 mmap_read_unlock(mm);
203map_err_nosemaphore:
204 current->thread.signo = SIGSEGV;
205 current->thread.code = SEGV_MAPERR;
206 current->thread.faddr = address;
207 return send_fault_sig(regs);
208
209acc_err:
210 current->thread.signo = SIGSEGV;
211 current->thread.code = SEGV_ACCERR;
212 current->thread.faddr = address;
213
214send_sig:
215 mmap_read_unlock(mm);
216 return send_fault_sig(regs);
217}
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#include <linux/uaccess.h>
14
15#include <asm/setup.h>
16#include <asm/traps.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 (faulthandler_disabled() || !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_SIGSEGV)
149 goto map_err;
150 else if (fault & VM_FAULT_SIGBUS)
151 goto bus_err;
152 BUG();
153 }
154
155 /*
156 * Major/minor page fault accounting is only done on the
157 * initial attempt. If we go through a retry, it is extremely
158 * likely that the page will be found in page cache at that point.
159 */
160 if (flags & FAULT_FLAG_ALLOW_RETRY) {
161 if (fault & VM_FAULT_MAJOR)
162 current->maj_flt++;
163 else
164 current->min_flt++;
165 if (fault & VM_FAULT_RETRY) {
166 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
167 * of starvation. */
168 flags &= ~FAULT_FLAG_ALLOW_RETRY;
169 flags |= FAULT_FLAG_TRIED;
170
171 /*
172 * No need to up_read(&mm->mmap_sem) as we would
173 * have already released it in __lock_page_or_retry
174 * in mm/filemap.c.
175 */
176
177 goto retry;
178 }
179 }
180
181 up_read(&mm->mmap_sem);
182 return 0;
183
184/*
185 * We ran out of memory, or some other thing happened to us that made
186 * us unable to handle the page fault gracefully.
187 */
188out_of_memory:
189 up_read(&mm->mmap_sem);
190 if (!user_mode(regs))
191 goto no_context;
192 pagefault_out_of_memory();
193 return 0;
194
195no_context:
196 current->thread.signo = SIGBUS;
197 current->thread.faddr = address;
198 return send_fault_sig(regs);
199
200bus_err:
201 current->thread.signo = SIGBUS;
202 current->thread.code = BUS_ADRERR;
203 current->thread.faddr = address;
204 goto send_sig;
205
206map_err:
207 current->thread.signo = SIGSEGV;
208 current->thread.code = SEGV_MAPERR;
209 current->thread.faddr = address;
210 goto send_sig;
211
212acc_err:
213 current->thread.signo = SIGSEGV;
214 current->thread.code = SEGV_ACCERR;
215 current->thread.faddr = address;
216
217send_sig:
218 up_read(&mm->mmap_sem);
219 return send_fault_sig(regs);
220}