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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
20extern void die_if_kernel(char *, struct pt_regs *, long);
21
22int send_fault_sig(struct pt_regs *regs)
23{
24 int signo, si_code;
25 void __user *addr;
26
27 signo = current->thread.signo;
28 si_code = current->thread.code;
29 addr = (void __user *)current->thread.faddr;
30 pr_debug("send_fault_sig: %p,%d,%d\n", addr, signo, si_code);
31
32 if (user_mode(regs)) {
33 force_sig_fault(signo, si_code, addr);
34 } else {
35 if (fixup_exception(regs))
36 return -1;
37
38 //if (signo == SIGBUS)
39 // force_sig_fault(si_signo, si_code, addr);
40
41 /*
42 * Oops. The kernel tried to access some bad page. We'll have to
43 * terminate things with extreme prejudice.
44 */
45 if ((unsigned long)addr < PAGE_SIZE)
46 pr_alert("Unable to handle kernel NULL pointer dereference");
47 else
48 pr_alert("Unable to handle kernel access");
49 pr_cont(" at virtual address %p\n", addr);
50 die_if_kernel("Oops", regs, 0 /*error_code*/);
51 make_task_dead(SIGKILL);
52 }
53
54 return 1;
55}
56
57/*
58 * This routine handles page faults. It determines the problem, and
59 * then passes it off to one of the appropriate routines.
60 *
61 * error_code:
62 * bit 0 == 0 means no page found, 1 means protection fault
63 * bit 1 == 0 means read, 1 means write
64 *
65 * If this routine detects a bad access, it returns 1, otherwise it
66 * returns 0.
67 */
68int do_page_fault(struct pt_regs *regs, unsigned long address,
69 unsigned long error_code)
70{
71 struct mm_struct *mm = current->mm;
72 struct vm_area_struct * vma;
73 vm_fault_t fault;
74 unsigned int flags = FAULT_FLAG_DEFAULT;
75
76 pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
77 regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);
78
79 /*
80 * If we're in an interrupt or have no user
81 * context, we must not take the fault..
82 */
83 if (faulthandler_disabled() || !mm)
84 goto no_context;
85
86 if (user_mode(regs))
87 flags |= FAULT_FLAG_USER;
88
89 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
90retry:
91 mmap_read_lock(mm);
92
93 vma = find_vma(mm, address);
94 if (!vma)
95 goto map_err;
96 if (vma->vm_start <= address)
97 goto good_area;
98 if (!(vma->vm_flags & VM_GROWSDOWN))
99 goto map_err;
100 if (user_mode(regs)) {
101 /* Accessing the stack below usp is always a bug. The
102 "+ 256" is there due to some instructions doing
103 pre-decrement on the stack and that doesn't show up
104 until later. */
105 if (address + 256 < rdusp())
106 goto map_err;
107 }
108 if (expand_stack(vma, address))
109 goto map_err;
110
111/*
112 * Ok, we have a good vm_area for this memory access, so
113 * we can handle it..
114 */
115good_area:
116 pr_debug("do_page_fault: good_area\n");
117 switch (error_code & 3) {
118 default: /* 3: write, present */
119 fallthrough;
120 case 2: /* write, not present */
121 if (!(vma->vm_flags & VM_WRITE))
122 goto acc_err;
123 flags |= FAULT_FLAG_WRITE;
124 break;
125 case 1: /* read, present */
126 goto acc_err;
127 case 0: /* read, not present */
128 if (unlikely(!vma_is_accessible(vma)))
129 goto acc_err;
130 }
131
132 /*
133 * If for any reason at all we couldn't handle the fault,
134 * make sure we exit gracefully rather than endlessly redo
135 * the fault.
136 */
137
138 fault = handle_mm_fault(vma, address, flags, regs);
139 pr_debug("handle_mm_fault returns %x\n", fault);
140
141 if (fault_signal_pending(fault, regs))
142 return 0;
143
144 /* The fault is fully completed (including releasing mmap lock) */
145 if (fault & VM_FAULT_COMPLETED)
146 return 0;
147
148 if (unlikely(fault & VM_FAULT_ERROR)) {
149 if (fault & VM_FAULT_OOM)
150 goto out_of_memory;
151 else if (fault & VM_FAULT_SIGSEGV)
152 goto map_err;
153 else if (fault & VM_FAULT_SIGBUS)
154 goto bus_err;
155 BUG();
156 }
157
158 if (fault & VM_FAULT_RETRY) {
159 flags |= FAULT_FLAG_TRIED;
160
161 /*
162 * No need to mmap_read_unlock(mm) as we would
163 * have already released it in __lock_page_or_retry
164 * in mm/filemap.c.
165 */
166
167 goto retry;
168 }
169
170 mmap_read_unlock(mm);
171 return 0;
172
173/*
174 * We ran out of memory, or some other thing happened to us that made
175 * us unable to handle the page fault gracefully.
176 */
177out_of_memory:
178 mmap_read_unlock(mm);
179 if (!user_mode(regs))
180 goto no_context;
181 pagefault_out_of_memory();
182 return 0;
183
184no_context:
185 current->thread.signo = SIGBUS;
186 current->thread.faddr = address;
187 return send_fault_sig(regs);
188
189bus_err:
190 current->thread.signo = SIGBUS;
191 current->thread.code = BUS_ADRERR;
192 current->thread.faddr = address;
193 goto send_sig;
194
195map_err:
196 current->thread.signo = SIGSEGV;
197 current->thread.code = SEGV_MAPERR;
198 current->thread.faddr = address;
199 goto send_sig;
200
201acc_err:
202 current->thread.signo = SIGSEGV;
203 current->thread.code = SEGV_ACCERR;
204 current->thread.faddr = address;
205
206send_sig:
207 mmap_read_unlock(mm);
208 return send_fault_sig(regs);
209}
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}