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Commit | Line | Data |
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ea2ba7dc | 1 | /* |
1da177e4 LT |
2 | * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com) |
3 | * Licensed under the GPL | |
4 | */ | |
5 | ||
6 | #include "linux/kernel.h" | |
7 | #include "asm/errno.h" | |
8 | #include "linux/sched.h" | |
9 | #include "linux/mm.h" | |
10 | #include "linux/spinlock.h" | |
11 | #include "linux/config.h" | |
12 | #include "linux/init.h" | |
13 | #include "linux/ptrace.h" | |
14 | #include "asm/semaphore.h" | |
15 | #include "asm/pgtable.h" | |
16 | #include "asm/pgalloc.h" | |
17 | #include "asm/tlbflush.h" | |
18 | #include "asm/a.out.h" | |
19 | #include "asm/current.h" | |
20 | #include "asm/irq.h" | |
546fe1cb | 21 | #include "sysdep/sigcontext.h" |
1da177e4 LT |
22 | #include "user_util.h" |
23 | #include "kern_util.h" | |
24 | #include "kern.h" | |
25 | #include "chan_kern.h" | |
26 | #include "mconsole_kern.h" | |
1da177e4 LT |
27 | #include "mem.h" |
28 | #include "mem_kern.h" | |
be662a18 PBG |
29 | #ifdef CONFIG_MODE_SKAS |
30 | #include "skas.h" | |
31 | #endif | |
ea2ba7dc | 32 | #include "os.h" |
1da177e4 | 33 | |
3b52166c | 34 | /* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */ |
1da177e4 LT |
35 | int handle_page_fault(unsigned long address, unsigned long ip, |
36 | int is_write, int is_user, int *code_out) | |
37 | { | |
38 | struct mm_struct *mm = current->mm; | |
39 | struct vm_area_struct *vma; | |
40 | pgd_t *pgd; | |
41 | pud_t *pud; | |
42 | pmd_t *pmd; | |
43 | pte_t *pte; | |
1da177e4 LT |
44 | int err = -EFAULT; |
45 | ||
46 | *code_out = SEGV_MAPERR; | |
fea03cb4 PBG |
47 | |
48 | /* If the fault was during atomic operation, don't take the fault, just | |
49 | * fail. */ | |
50 | if (in_atomic()) | |
51 | goto out_nosemaphore; | |
52 | ||
1da177e4 LT |
53 | down_read(&mm->mmap_sem); |
54 | vma = find_vma(mm, address); | |
55 | if(!vma) | |
56 | goto out; | |
57 | else if(vma->vm_start <= address) | |
58 | goto good_area; | |
59 | else if(!(vma->vm_flags & VM_GROWSDOWN)) | |
60 | goto out; | |
2d58cc9a | 61 | else if(is_user && !ARCH_IS_STACKGROW(address)) |
1da177e4 LT |
62 | goto out; |
63 | else if(expand_stack(vma, address)) | |
64 | goto out; | |
65 | ||
3b52166c | 66 | good_area: |
1da177e4 LT |
67 | *code_out = SEGV_ACCERR; |
68 | if(is_write && !(vma->vm_flags & VM_WRITE)) | |
69 | goto out; | |
13479d52 | 70 | |
d129f312 PBG |
71 | /* Don't require VM_READ|VM_EXEC for write faults! */ |
72 | if(!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC))) | |
13479d52 JD |
73 | goto out; |
74 | ||
1da177e4 | 75 | do { |
3b52166c | 76 | survive: |
1da177e4 LT |
77 | switch (handle_mm_fault(mm, vma, address, is_write)){ |
78 | case VM_FAULT_MINOR: | |
79 | current->min_flt++; | |
80 | break; | |
81 | case VM_FAULT_MAJOR: | |
82 | current->maj_flt++; | |
83 | break; | |
84 | case VM_FAULT_SIGBUS: | |
85 | err = -EACCES; | |
86 | goto out; | |
87 | case VM_FAULT_OOM: | |
88 | err = -ENOMEM; | |
89 | goto out_of_memory; | |
90 | default: | |
91 | BUG(); | |
92 | } | |
3b52166c PBG |
93 | pgd = pgd_offset(mm, address); |
94 | pud = pud_offset(pgd, address); | |
95 | pmd = pmd_offset(pud, address); | |
96 | pte = pte_offset_kernel(pmd, address); | |
1da177e4 LT |
97 | } while(!pte_present(*pte)); |
98 | err = 0; | |
cbc24afa PBG |
99 | /* The below warning was added in place of |
100 | * pte_mkyoung(); if (is_write) pte_mkdirty(); | |
101 | * If it's triggered, we'd see normally a hang here (a clean pte is | |
102 | * marked read-only to emulate the dirty bit). | |
103 | * However, the generic code can mark a PTE writable but clean on a | |
104 | * concurrent read fault, triggering this harmlessly. So comment it out. | |
105 | */ | |
106 | #if 0 | |
16b03678 | 107 | WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte))); |
cbc24afa | 108 | #endif |
3b52166c PBG |
109 | flush_tlb_page(vma, address); |
110 | out: | |
1da177e4 | 111 | up_read(&mm->mmap_sem); |
fea03cb4 | 112 | out_nosemaphore: |
1da177e4 LT |
113 | return(err); |
114 | ||
115 | /* | |
116 | * We ran out of memory, or some other thing happened to us that made | |
117 | * us unable to handle the page fault gracefully. | |
118 | */ | |
119 | out_of_memory: | |
120 | if (current->pid == 1) { | |
121 | up_read(&mm->mmap_sem); | |
122 | yield(); | |
123 | down_read(&mm->mmap_sem); | |
124 | goto survive; | |
125 | } | |
126 | goto out; | |
127 | } | |
128 | ||
ea2ba7dc GS |
129 | struct kern_handlers handlinfo_kern = { |
130 | .relay_signal = relay_signal, | |
131 | .winch = winch, | |
132 | .bus_handler = relay_signal, | |
133 | .page_fault = segv_handler, | |
134 | .sigio_handler = sigio_handler, | |
135 | .timer_handler = timer_handler | |
136 | }; | |
c578455a BS |
137 | /* |
138 | * We give a *copy* of the faultinfo in the regs to segv. | |
139 | * This must be done, since nesting SEGVs could overwrite | |
140 | * the info in the regs. A pointer to the info then would | |
141 | * give us bad data! | |
142 | */ | |
143 | unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc) | |
1da177e4 LT |
144 | { |
145 | struct siginfo si; | |
146 | void *catcher; | |
147 | int err; | |
c578455a BS |
148 | int is_write = FAULT_WRITE(fi); |
149 | unsigned long address = FAULT_ADDRESS(fi); | |
1da177e4 LT |
150 | |
151 | if(!is_user && (address >= start_vm) && (address < end_vm)){ | |
152 | flush_tlb_kernel_vm(); | |
153 | return(0); | |
154 | } | |
1da177e4 LT |
155 | else if(current->mm == NULL) |
156 | panic("Segfault with no mm"); | |
546fe1cb | 157 | |
be662a18 | 158 | if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi)) |
546fe1cb PBG |
159 | err = handle_page_fault(address, ip, is_write, is_user, &si.si_code); |
160 | else { | |
161 | err = -EFAULT; | |
162 | /* A thread accessed NULL, we get a fault, but CR2 is invalid. | |
163 | * This code is used in __do_copy_from_user() of TT mode. */ | |
164 | address = 0; | |
165 | } | |
1da177e4 LT |
166 | |
167 | catcher = current->thread.fault_catcher; | |
168 | if(!err) | |
169 | return(0); | |
170 | else if(catcher != NULL){ | |
171 | current->thread.fault_addr = (void *) address; | |
172 | do_longjmp(catcher, 1); | |
173 | } | |
174 | else if(current->thread.fault_addr != NULL) | |
175 | panic("fault_addr set but no fault catcher"); | |
c578455a | 176 | else if(!is_user && arch_fixup(ip, sc)) |
1da177e4 LT |
177 | return(0); |
178 | ||
179 | if(!is_user) | |
180 | panic("Kernel mode fault at addr 0x%lx, ip 0x%lx", | |
181 | address, ip); | |
182 | ||
3b52166c | 183 | if (err == -EACCES) { |
1da177e4 LT |
184 | si.si_signo = SIGBUS; |
185 | si.si_errno = 0; | |
186 | si.si_code = BUS_ADRERR; | |
187 | si.si_addr = (void *)address; | |
c578455a | 188 | current->thread.arch.faultinfo = fi; |
1da177e4 | 189 | force_sig_info(SIGBUS, &si, current); |
3b52166c | 190 | } else if (err == -ENOMEM) { |
1da177e4 LT |
191 | printk("VM: killing process %s\n", current->comm); |
192 | do_exit(SIGKILL); | |
3b52166c PBG |
193 | } else { |
194 | BUG_ON(err != -EFAULT); | |
1da177e4 LT |
195 | si.si_signo = SIGSEGV; |
196 | si.si_addr = (void *) address; | |
c578455a | 197 | current->thread.arch.faultinfo = fi; |
1da177e4 LT |
198 | force_sig_info(SIGSEGV, &si, current); |
199 | } | |
200 | return(0); | |
201 | } | |
202 | ||
c578455a | 203 | void bad_segv(struct faultinfo fi, unsigned long ip) |
1da177e4 LT |
204 | { |
205 | struct siginfo si; | |
206 | ||
207 | si.si_signo = SIGSEGV; | |
208 | si.si_code = SEGV_ACCERR; | |
c578455a BS |
209 | si.si_addr = (void *) FAULT_ADDRESS(fi); |
210 | current->thread.arch.faultinfo = fi; | |
1da177e4 LT |
211 | force_sig_info(SIGSEGV, &si, current); |
212 | } | |
213 | ||
214 | void relay_signal(int sig, union uml_pt_regs *regs) | |
215 | { | |
216 | if(arch_handle_signal(sig, regs)) return; | |
217 | if(!UPT_IS_USER(regs)) | |
218 | panic("Kernel mode signal %d", sig); | |
c578455a | 219 | current->thread.arch.faultinfo = *UPT_FAULTINFO(regs); |
1da177e4 LT |
220 | force_sig(sig, current); |
221 | } | |
222 | ||
223 | void bus_handler(int sig, union uml_pt_regs *regs) | |
224 | { | |
225 | if(current->thread.fault_catcher != NULL) | |
226 | do_longjmp(current->thread.fault_catcher, 1); | |
227 | else relay_signal(sig, regs); | |
228 | } | |
229 | ||
230 | void winch(int sig, union uml_pt_regs *regs) | |
231 | { | |
232 | do_IRQ(WINCH_IRQ, regs); | |
233 | } | |
234 | ||
235 | void trap_init(void) | |
236 | { | |
237 | } |