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Commit | Line | Data |
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ea2ba7dc | 1 | /* |
4c9e1385 | 2 | * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) |
1da177e4 LT |
3 | * Licensed under the GPL |
4 | */ | |
5 | ||
4c9e1385 JD |
6 | #include <linux/mm.h> |
7 | #include <linux/sched.h> | |
8 | #include <linux/hardirq.h> | |
73395a00 | 9 | #include <linux/module.h> |
4c9e1385 JD |
10 | #include <asm/current.h> |
11 | #include <asm/pgtable.h> | |
12 | #include <asm/tlbflush.h> | |
eb830759 | 13 | #include "arch.h" |
4c9e1385 JD |
14 | #include "as-layout.h" |
15 | #include "kern_util.h" | |
ea2ba7dc | 16 | #include "os.h" |
d83ecf08 | 17 | #include "skas.h" |
1da177e4 | 18 | |
4c9e1385 JD |
19 | /* |
20 | * Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by | |
21 | * segv(). | |
22 | */ | |
1d3468a6 | 23 | int handle_page_fault(unsigned long address, unsigned long ip, |
1da177e4 LT |
24 | int is_write, int is_user, int *code_out) |
25 | { | |
26 | struct mm_struct *mm = current->mm; | |
27 | struct vm_area_struct *vma; | |
28 | pgd_t *pgd; | |
29 | pud_t *pud; | |
30 | pmd_t *pmd; | |
31 | pte_t *pte; | |
1da177e4 | 32 | int err = -EFAULT; |
1cefe28f KC |
33 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE | |
34 | (is_write ? FAULT_FLAG_WRITE : 0); | |
1da177e4 LT |
35 | |
36 | *code_out = SEGV_MAPERR; | |
fea03cb4 | 37 | |
4c9e1385 JD |
38 | /* |
39 | * If the fault was during atomic operation, don't take the fault, just | |
40 | * fail. | |
41 | */ | |
fea03cb4 PBG |
42 | if (in_atomic()) |
43 | goto out_nosemaphore; | |
44 | ||
1cefe28f | 45 | retry: |
1da177e4 LT |
46 | down_read(&mm->mmap_sem); |
47 | vma = find_vma(mm, address); | |
4c9e1385 | 48 | if (!vma) |
1da177e4 | 49 | goto out; |
4c9e1385 | 50 | else if (vma->vm_start <= address) |
1da177e4 | 51 | goto good_area; |
4c9e1385 | 52 | else if (!(vma->vm_flags & VM_GROWSDOWN)) |
1da177e4 | 53 | goto out; |
4c9e1385 | 54 | else if (is_user && !ARCH_IS_STACKGROW(address)) |
1da177e4 | 55 | goto out; |
4c9e1385 | 56 | else if (expand_stack(vma, address)) |
1da177e4 LT |
57 | goto out; |
58 | ||
3b52166c | 59 | good_area: |
1da177e4 | 60 | *code_out = SEGV_ACCERR; |
4c9e1385 | 61 | if (is_write && !(vma->vm_flags & VM_WRITE)) |
1da177e4 | 62 | goto out; |
13479d52 | 63 | |
d129f312 | 64 | /* Don't require VM_READ|VM_EXEC for write faults! */ |
4c9e1385 | 65 | if (!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC))) |
5d86456d | 66 | goto out; |
13479d52 | 67 | |
1da177e4 | 68 | do { |
83c54070 | 69 | int fault; |
1c0fe6e3 | 70 | |
1cefe28f KC |
71 | fault = handle_mm_fault(mm, vma, address, flags); |
72 | ||
73 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) | |
74 | goto out_nosemaphore; | |
75 | ||
83c54070 NP |
76 | if (unlikely(fault & VM_FAULT_ERROR)) { |
77 | if (fault & VM_FAULT_OOM) { | |
83c54070 NP |
78 | goto out_of_memory; |
79 | } else if (fault & VM_FAULT_SIGBUS) { | |
80 | err = -EACCES; | |
81 | goto out; | |
82 | } | |
1da177e4 LT |
83 | BUG(); |
84 | } | |
1cefe28f KC |
85 | if (flags & FAULT_FLAG_ALLOW_RETRY) { |
86 | if (fault & VM_FAULT_MAJOR) | |
87 | current->maj_flt++; | |
88 | else | |
89 | current->min_flt++; | |
90 | if (fault & VM_FAULT_RETRY) { | |
91 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
92 | ||
93 | goto retry; | |
94 | } | |
95 | } | |
83c54070 | 96 | |
3b52166c PBG |
97 | pgd = pgd_offset(mm, address); |
98 | pud = pud_offset(pgd, address); | |
99 | pmd = pmd_offset(pud, address); | |
100 | pte = pte_offset_kernel(pmd, address); | |
4c9e1385 | 101 | } while (!pte_present(*pte)); |
1da177e4 | 102 | err = 0; |
4c9e1385 JD |
103 | /* |
104 | * The below warning was added in place of | |
cbc24afa PBG |
105 | * pte_mkyoung(); if (is_write) pte_mkdirty(); |
106 | * If it's triggered, we'd see normally a hang here (a clean pte is | |
107 | * marked read-only to emulate the dirty bit). | |
108 | * However, the generic code can mark a PTE writable but clean on a | |
109 | * concurrent read fault, triggering this harmlessly. So comment it out. | |
110 | */ | |
111 | #if 0 | |
16b03678 | 112 | WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte))); |
cbc24afa | 113 | #endif |
3b52166c PBG |
114 | flush_tlb_page(vma, address); |
115 | out: | |
1da177e4 | 116 | up_read(&mm->mmap_sem); |
fea03cb4 | 117 | out_nosemaphore: |
4c9e1385 | 118 | return err; |
1da177e4 | 119 | |
1da177e4 | 120 | out_of_memory: |
1c0fe6e3 NP |
121 | /* |
122 | * We ran out of memory, call the OOM killer, and return the userspace | |
123 | * (which will retry the fault, or kill us if we got oom-killed). | |
124 | */ | |
125 | up_read(&mm->mmap_sem); | |
126 | pagefault_out_of_memory(); | |
127 | return 0; | |
1da177e4 | 128 | } |
73395a00 | 129 | EXPORT_SYMBOL(handle_page_fault); |
1da177e4 | 130 | |
3ef6130a RW |
131 | static void show_segv_info(struct uml_pt_regs *regs) |
132 | { | |
133 | struct task_struct *tsk = current; | |
134 | struct faultinfo *fi = UPT_FAULTINFO(regs); | |
135 | ||
136 | if (!unhandled_signal(tsk, SIGSEGV)) | |
137 | return; | |
138 | ||
139 | if (!printk_ratelimit()) | |
140 | return; | |
141 | ||
142 | printk("%s%s[%d]: segfault at %lx ip %p sp %p error %x", | |
143 | task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, | |
144 | tsk->comm, task_pid_nr(tsk), FAULT_ADDRESS(*fi), | |
145 | (void *)UPT_IP(regs), (void *)UPT_SP(regs), | |
146 | fi->error_code); | |
147 | ||
148 | print_vma_addr(KERN_CONT " in ", UPT_IP(regs)); | |
149 | printk(KERN_CONT "\n"); | |
150 | } | |
151 | ||
27aa6ef3 JD |
152 | static void bad_segv(struct faultinfo fi, unsigned long ip) |
153 | { | |
154 | struct siginfo si; | |
155 | ||
156 | si.si_signo = SIGSEGV; | |
157 | si.si_code = SEGV_ACCERR; | |
158 | si.si_addr = (void __user *) FAULT_ADDRESS(fi); | |
159 | current->thread.arch.faultinfo = fi; | |
160 | force_sig_info(SIGSEGV, &si, current); | |
161 | } | |
162 | ||
3e6f2ac4 JD |
163 | void fatal_sigsegv(void) |
164 | { | |
165 | force_sigsegv(SIGSEGV, current); | |
166 | do_signal(); | |
167 | /* | |
168 | * This is to tell gcc that we're not returning - do_signal | |
169 | * can, in general, return, but in this case, it's not, since | |
170 | * we just got a fatal SIGSEGV queued. | |
171 | */ | |
172 | os_dump_core(); | |
173 | } | |
174 | ||
d3c1cfcd | 175 | void segv_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs) |
c66fdd5e GS |
176 | { |
177 | struct faultinfo * fi = UPT_FAULTINFO(regs); | |
178 | ||
4c9e1385 | 179 | if (UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)) { |
3ef6130a | 180 | show_segv_info(regs); |
c66fdd5e GS |
181 | bad_segv(*fi, UPT_IP(regs)); |
182 | return; | |
183 | } | |
184 | segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs); | |
185 | } | |
186 | ||
c578455a BS |
187 | /* |
188 | * We give a *copy* of the faultinfo in the regs to segv. | |
189 | * This must be done, since nesting SEGVs could overwrite | |
190 | * the info in the regs. A pointer to the info then would | |
191 | * give us bad data! | |
192 | */ | |
5d86456d | 193 | unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, |
77bf4400 | 194 | struct uml_pt_regs *regs) |
1da177e4 LT |
195 | { |
196 | struct siginfo si; | |
fab95c55 | 197 | jmp_buf *catcher; |
1da177e4 | 198 | int err; |
5d86456d JD |
199 | int is_write = FAULT_WRITE(fi); |
200 | unsigned long address = FAULT_ADDRESS(fi); | |
1da177e4 | 201 | |
4c9e1385 | 202 | if (!is_user && (address >= start_vm) && (address < end_vm)) { |
5d86456d JD |
203 | flush_tlb_kernel_vm(); |
204 | return 0; | |
205 | } | |
4c9e1385 | 206 | else if (current->mm == NULL) { |
377fad3a | 207 | show_regs(container_of(regs, struct pt_regs, regs)); |
4c9e1385 | 208 | panic("Segfault with no mm"); |
377fad3a | 209 | } |
546fe1cb | 210 | |
be662a18 | 211 | if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi)) |
4c9e1385 JD |
212 | err = handle_page_fault(address, ip, is_write, is_user, |
213 | &si.si_code); | |
546fe1cb PBG |
214 | else { |
215 | err = -EFAULT; | |
4c9e1385 JD |
216 | /* |
217 | * A thread accessed NULL, we get a fault, but CR2 is invalid. | |
218 | * This code is used in __do_copy_from_user() of TT mode. | |
219 | * XXX tt mode is gone, so maybe this isn't needed any more | |
220 | */ | |
546fe1cb PBG |
221 | address = 0; |
222 | } | |
1da177e4 LT |
223 | |
224 | catcher = current->thread.fault_catcher; | |
4c9e1385 | 225 | if (!err) |
5d86456d | 226 | return 0; |
4c9e1385 | 227 | else if (catcher != NULL) { |
1da177e4 | 228 | current->thread.fault_addr = (void *) address; |
fab95c55 | 229 | UML_LONGJMP(catcher, 1); |
1d3468a6 | 230 | } |
4c9e1385 | 231 | else if (current->thread.fault_addr != NULL) |
1da177e4 | 232 | panic("fault_addr set but no fault catcher"); |
4c9e1385 | 233 | else if (!is_user && arch_fixup(ip, regs)) |
5d86456d | 234 | return 0; |
1da177e4 | 235 | |
4c9e1385 | 236 | if (!is_user) { |
377fad3a | 237 | show_regs(container_of(regs, struct pt_regs, regs)); |
1d3468a6 | 238 | panic("Kernel mode fault at addr 0x%lx, ip 0x%lx", |
1da177e4 | 239 | address, ip); |
377fad3a | 240 | } |
1da177e4 | 241 | |
3ef6130a RW |
242 | show_segv_info(regs); |
243 | ||
3b52166c | 244 | if (err == -EACCES) { |
1da177e4 LT |
245 | si.si_signo = SIGBUS; |
246 | si.si_errno = 0; | |
247 | si.si_code = BUS_ADRERR; | |
4d338e1a | 248 | si.si_addr = (void __user *)address; |
5d86456d | 249 | current->thread.arch.faultinfo = fi; |
1da177e4 | 250 | force_sig_info(SIGBUS, &si, current); |
3b52166c PBG |
251 | } else { |
252 | BUG_ON(err != -EFAULT); | |
1da177e4 | 253 | si.si_signo = SIGSEGV; |
4d338e1a | 254 | si.si_addr = (void __user *) address; |
5d86456d | 255 | current->thread.arch.faultinfo = fi; |
1da177e4 LT |
256 | force_sig_info(SIGSEGV, &si, current); |
257 | } | |
5d86456d | 258 | return 0; |
1da177e4 LT |
259 | } |
260 | ||
d3c1cfcd | 261 | void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs) |
1da177e4 | 262 | { |
d3c1cfcd MP |
263 | struct faultinfo *fi; |
264 | struct siginfo clean_si; | |
265 | ||
4c9e1385 JD |
266 | if (!UPT_IS_USER(regs)) { |
267 | if (sig == SIGBUS) | |
268 | printk(KERN_ERR "Bus error - the host /dev/shm or /tmp " | |
269 | "mount likely just ran out of space\n"); | |
1da177e4 | 270 | panic("Kernel mode signal %d", sig); |
6edf428e JD |
271 | } |
272 | ||
9226b838 JD |
273 | arch_examine_signal(sig, regs); |
274 | ||
d3c1cfcd MP |
275 | memset(&clean_si, 0, sizeof(clean_si)); |
276 | clean_si.si_signo = si->si_signo; | |
277 | clean_si.si_errno = si->si_errno; | |
278 | clean_si.si_code = si->si_code; | |
279 | switch (sig) { | |
280 | case SIGILL: | |
281 | case SIGFPE: | |
282 | case SIGSEGV: | |
283 | case SIGBUS: | |
284 | case SIGTRAP: | |
285 | fi = UPT_FAULTINFO(regs); | |
286 | clean_si.si_addr = (void __user *) FAULT_ADDRESS(*fi); | |
287 | current->thread.arch.faultinfo = *fi; | |
288 | #ifdef __ARCH_SI_TRAPNO | |
289 | clean_si.si_trapno = si->si_trapno; | |
290 | #endif | |
291 | break; | |
292 | default: | |
293 | printk(KERN_ERR "Attempted to relay unknown signal %d (si_code = %d)\n", | |
294 | sig, si->si_code); | |
295 | } | |
296 | ||
297 | force_sig_info(sig, &clean_si, current); | |
1da177e4 LT |
298 | } |
299 | ||
d3c1cfcd | 300 | void bus_handler(int sig, struct siginfo *si, struct uml_pt_regs *regs) |
1da177e4 | 301 | { |
4c9e1385 | 302 | if (current->thread.fault_catcher != NULL) |
fab95c55 | 303 | UML_LONGJMP(current->thread.fault_catcher, 1); |
d3c1cfcd MP |
304 | else |
305 | relay_signal(sig, si, regs); | |
1da177e4 LT |
306 | } |
307 | ||
d3c1cfcd | 308 | void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs) |
1da177e4 LT |
309 | { |
310 | do_IRQ(WINCH_IRQ, regs); | |
311 | } | |
312 | ||
313 | void trap_init(void) | |
314 | { | |
315 | } |