Commit | Line | Data |
---|---|---|
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" | |
c66fdd5e GS |
29 | #include "sysdep/sigcontext.h" |
30 | #include "sysdep/ptrace.h" | |
31 | #include "os.h" | |
be662a18 PBG |
32 | #ifdef CONFIG_MODE_SKAS |
33 | #include "skas.h" | |
34 | #endif | |
ea2ba7dc | 35 | #include "os.h" |
1da177e4 | 36 | |
3b52166c | 37 | /* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */ |
1da177e4 LT |
38 | int handle_page_fault(unsigned long address, unsigned long ip, |
39 | int is_write, int is_user, int *code_out) | |
40 | { | |
41 | struct mm_struct *mm = current->mm; | |
42 | struct vm_area_struct *vma; | |
43 | pgd_t *pgd; | |
44 | pud_t *pud; | |
45 | pmd_t *pmd; | |
46 | pte_t *pte; | |
1da177e4 LT |
47 | int err = -EFAULT; |
48 | ||
49 | *code_out = SEGV_MAPERR; | |
fea03cb4 PBG |
50 | |
51 | /* If the fault was during atomic operation, don't take the fault, just | |
52 | * fail. */ | |
53 | if (in_atomic()) | |
54 | goto out_nosemaphore; | |
55 | ||
1da177e4 LT |
56 | down_read(&mm->mmap_sem); |
57 | vma = find_vma(mm, address); | |
58 | if(!vma) | |
59 | goto out; | |
60 | else if(vma->vm_start <= address) | |
61 | goto good_area; | |
62 | else if(!(vma->vm_flags & VM_GROWSDOWN)) | |
63 | goto out; | |
2d58cc9a | 64 | else if(is_user && !ARCH_IS_STACKGROW(address)) |
1da177e4 LT |
65 | goto out; |
66 | else if(expand_stack(vma, address)) | |
67 | goto out; | |
68 | ||
3b52166c | 69 | good_area: |
1da177e4 LT |
70 | *code_out = SEGV_ACCERR; |
71 | if(is_write && !(vma->vm_flags & VM_WRITE)) | |
72 | goto out; | |
13479d52 | 73 | |
d129f312 PBG |
74 | /* Don't require VM_READ|VM_EXEC for write faults! */ |
75 | if(!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC))) | |
13479d52 JD |
76 | goto out; |
77 | ||
1da177e4 | 78 | do { |
3b52166c | 79 | survive: |
1da177e4 LT |
80 | switch (handle_mm_fault(mm, vma, address, is_write)){ |
81 | case VM_FAULT_MINOR: | |
82 | current->min_flt++; | |
83 | break; | |
84 | case VM_FAULT_MAJOR: | |
85 | current->maj_flt++; | |
86 | break; | |
87 | case VM_FAULT_SIGBUS: | |
88 | err = -EACCES; | |
89 | goto out; | |
90 | case VM_FAULT_OOM: | |
91 | err = -ENOMEM; | |
92 | goto out_of_memory; | |
93 | default: | |
94 | BUG(); | |
95 | } | |
3b52166c PBG |
96 | pgd = pgd_offset(mm, address); |
97 | pud = pud_offset(pgd, address); | |
98 | pmd = pmd_offset(pud, address); | |
99 | pte = pte_offset_kernel(pmd, address); | |
1da177e4 LT |
100 | } while(!pte_present(*pte)); |
101 | err = 0; | |
cbc24afa PBG |
102 | /* The below warning was added in place of |
103 | * pte_mkyoung(); if (is_write) pte_mkdirty(); | |
104 | * If it's triggered, we'd see normally a hang here (a clean pte is | |
105 | * marked read-only to emulate the dirty bit). | |
106 | * However, the generic code can mark a PTE writable but clean on a | |
107 | * concurrent read fault, triggering this harmlessly. So comment it out. | |
108 | */ | |
109 | #if 0 | |
16b03678 | 110 | WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte))); |
cbc24afa | 111 | #endif |
3b52166c PBG |
112 | flush_tlb_page(vma, address); |
113 | out: | |
1da177e4 | 114 | up_read(&mm->mmap_sem); |
fea03cb4 | 115 | out_nosemaphore: |
1da177e4 LT |
116 | return(err); |
117 | ||
118 | /* | |
119 | * We ran out of memory, or some other thing happened to us that made | |
120 | * us unable to handle the page fault gracefully. | |
121 | */ | |
122 | out_of_memory: | |
123 | if (current->pid == 1) { | |
124 | up_read(&mm->mmap_sem); | |
125 | yield(); | |
126 | down_read(&mm->mmap_sem); | |
127 | goto survive; | |
128 | } | |
129 | goto out; | |
130 | } | |
131 | ||
c66fdd5e GS |
132 | void segv_handler(int sig, union uml_pt_regs *regs) |
133 | { | |
134 | struct faultinfo * fi = UPT_FAULTINFO(regs); | |
135 | ||
136 | if(UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)){ | |
137 | bad_segv(*fi, UPT_IP(regs)); | |
138 | return; | |
139 | } | |
140 | segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs); | |
141 | } | |
142 | ||
ea2ba7dc GS |
143 | struct kern_handlers handlinfo_kern = { |
144 | .relay_signal = relay_signal, | |
145 | .winch = winch, | |
146 | .bus_handler = relay_signal, | |
147 | .page_fault = segv_handler, | |
148 | .sigio_handler = sigio_handler, | |
149 | .timer_handler = timer_handler | |
150 | }; | |
c578455a BS |
151 | /* |
152 | * We give a *copy* of the faultinfo in the regs to segv. | |
153 | * This must be done, since nesting SEGVs could overwrite | |
154 | * the info in the regs. A pointer to the info then would | |
155 | * give us bad data! | |
156 | */ | |
157 | unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc) | |
1da177e4 LT |
158 | { |
159 | struct siginfo si; | |
160 | void *catcher; | |
161 | int err; | |
c578455a BS |
162 | int is_write = FAULT_WRITE(fi); |
163 | unsigned long address = FAULT_ADDRESS(fi); | |
1da177e4 LT |
164 | |
165 | if(!is_user && (address >= start_vm) && (address < end_vm)){ | |
166 | flush_tlb_kernel_vm(); | |
167 | return(0); | |
168 | } | |
1da177e4 LT |
169 | else if(current->mm == NULL) |
170 | panic("Segfault with no mm"); | |
546fe1cb | 171 | |
be662a18 | 172 | if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi)) |
546fe1cb PBG |
173 | err = handle_page_fault(address, ip, is_write, is_user, &si.si_code); |
174 | else { | |
175 | err = -EFAULT; | |
176 | /* A thread accessed NULL, we get a fault, but CR2 is invalid. | |
177 | * This code is used in __do_copy_from_user() of TT mode. */ | |
178 | address = 0; | |
179 | } | |
1da177e4 LT |
180 | |
181 | catcher = current->thread.fault_catcher; | |
182 | if(!err) | |
183 | return(0); | |
184 | else if(catcher != NULL){ | |
185 | current->thread.fault_addr = (void *) address; | |
186 | do_longjmp(catcher, 1); | |
187 | } | |
188 | else if(current->thread.fault_addr != NULL) | |
189 | panic("fault_addr set but no fault catcher"); | |
c578455a | 190 | else if(!is_user && arch_fixup(ip, sc)) |
1da177e4 LT |
191 | return(0); |
192 | ||
193 | if(!is_user) | |
194 | panic("Kernel mode fault at addr 0x%lx, ip 0x%lx", | |
195 | address, ip); | |
196 | ||
3b52166c | 197 | if (err == -EACCES) { |
1da177e4 LT |
198 | si.si_signo = SIGBUS; |
199 | si.si_errno = 0; | |
200 | si.si_code = BUS_ADRERR; | |
201 | si.si_addr = (void *)address; | |
c578455a | 202 | current->thread.arch.faultinfo = fi; |
1da177e4 | 203 | force_sig_info(SIGBUS, &si, current); |
3b52166c | 204 | } else if (err == -ENOMEM) { |
1da177e4 LT |
205 | printk("VM: killing process %s\n", current->comm); |
206 | do_exit(SIGKILL); | |
3b52166c PBG |
207 | } else { |
208 | BUG_ON(err != -EFAULT); | |
1da177e4 LT |
209 | si.si_signo = SIGSEGV; |
210 | si.si_addr = (void *) address; | |
c578455a | 211 | current->thread.arch.faultinfo = fi; |
1da177e4 LT |
212 | force_sig_info(SIGSEGV, &si, current); |
213 | } | |
214 | return(0); | |
215 | } | |
216 | ||
c578455a | 217 | void bad_segv(struct faultinfo fi, unsigned long ip) |
1da177e4 LT |
218 | { |
219 | struct siginfo si; | |
220 | ||
221 | si.si_signo = SIGSEGV; | |
222 | si.si_code = SEGV_ACCERR; | |
c578455a BS |
223 | si.si_addr = (void *) FAULT_ADDRESS(fi); |
224 | current->thread.arch.faultinfo = fi; | |
1da177e4 LT |
225 | force_sig_info(SIGSEGV, &si, current); |
226 | } | |
227 | ||
228 | void relay_signal(int sig, union uml_pt_regs *regs) | |
229 | { | |
230 | if(arch_handle_signal(sig, regs)) return; | |
231 | if(!UPT_IS_USER(regs)) | |
232 | panic("Kernel mode signal %d", sig); | |
c578455a | 233 | current->thread.arch.faultinfo = *UPT_FAULTINFO(regs); |
1da177e4 LT |
234 | force_sig(sig, current); |
235 | } | |
236 | ||
237 | void bus_handler(int sig, union uml_pt_regs *regs) | |
238 | { | |
239 | if(current->thread.fault_catcher != NULL) | |
240 | do_longjmp(current->thread.fault_catcher, 1); | |
241 | else relay_signal(sig, regs); | |
242 | } | |
243 | ||
244 | void winch(int sig, union uml_pt_regs *regs) | |
245 | { | |
246 | do_IRQ(WINCH_IRQ, regs); | |
247 | } | |
248 | ||
249 | void trap_init(void) | |
250 | { | |
251 | } |