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[linux-3.10.git] / arch / um / kernel / trap_kern.c
1 /* 
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"
21 #include "user_util.h"
22 #include "kern_util.h"
23 #include "kern.h"
24 #include "chan_kern.h"
25 #include "mconsole_kern.h"
26 #include "2_5compat.h"
27 #include "mem.h"
28 #include "mem_kern.h"
29
30 int handle_page_fault(unsigned long address, unsigned long ip, 
31                       int is_write, int is_user, int *code_out)
32 {
33         struct mm_struct *mm = current->mm;
34         struct vm_area_struct *vma;
35         pgd_t *pgd;
36         pud_t *pud;
37         pmd_t *pmd;
38         pte_t *pte;
39         unsigned long page;
40         int err = -EFAULT;
41
42         *code_out = SEGV_MAPERR;
43         down_read(&mm->mmap_sem);
44         vma = find_vma(mm, address);
45         if(!vma) 
46                 goto out;
47         else if(vma->vm_start <= address) 
48                 goto good_area;
49         else if(!(vma->vm_flags & VM_GROWSDOWN)) 
50                 goto out;
51         else if(is_user && !ARCH_IS_STACKGROW(address))
52                 goto out;
53         else if(expand_stack(vma, address)) 
54                 goto out;
55
56  good_area:
57         *code_out = SEGV_ACCERR;
58         if(is_write && !(vma->vm_flags & VM_WRITE)) 
59                 goto out;
60         page = address & PAGE_MASK;
61         pgd = pgd_offset(mm, page);
62         pud = pud_offset(pgd, page);
63         pmd = pmd_offset(pud, page);
64         do {
65  survive:
66                 switch (handle_mm_fault(mm, vma, address, is_write)){
67                 case VM_FAULT_MINOR:
68                         current->min_flt++;
69                         break;
70                 case VM_FAULT_MAJOR:
71                         current->maj_flt++;
72                         break;
73                 case VM_FAULT_SIGBUS:
74                         err = -EACCES;
75                         goto out;
76                 case VM_FAULT_OOM:
77                         err = -ENOMEM;
78                         goto out_of_memory;
79                 default:
80                         BUG();
81                 }
82                 pgd = pgd_offset(mm, page);
83                 pud = pud_offset(pgd, page);
84                 pmd = pmd_offset(pud, page);
85                 pte = pte_offset_kernel(pmd, page);
86         } while(!pte_present(*pte));
87         err = 0;
88         *pte = pte_mkyoung(*pte);
89         if(pte_write(*pte)) *pte = pte_mkdirty(*pte);
90         flush_tlb_page(vma, page);
91  out:
92         up_read(&mm->mmap_sem);
93         return(err);
94
95 /*
96  * We ran out of memory, or some other thing happened to us that made
97  * us unable to handle the page fault gracefully.
98  */
99 out_of_memory:
100         if (current->pid == 1) {
101                 up_read(&mm->mmap_sem);
102                 yield();
103                 down_read(&mm->mmap_sem);
104                 goto survive;
105         }
106         goto out;
107 }
108
109 LIST_HEAD(physmem_remappers);
110
111 void register_remapper(struct remapper *info)
112 {
113         list_add(&info->list, &physmem_remappers);
114 }
115
116 static int check_remapped_addr(unsigned long address, int is_write)
117 {
118         struct remapper *remapper;
119         struct list_head *ele;
120         __u64 offset;
121         int fd;
122
123         fd = phys_mapping(__pa(address), &offset);
124         if(fd == -1)
125                 return(0);
126
127         list_for_each(ele, &physmem_remappers){
128                 remapper = list_entry(ele, struct remapper, list);
129                 if((*remapper->proc)(fd, address, is_write, offset))
130                         return(1);
131         }
132
133         return(0);
134 }
135
136 /*
137  * We give a *copy* of the faultinfo in the regs to segv.
138  * This must be done, since nesting SEGVs could overwrite
139  * the info in the regs. A pointer to the info then would
140  * give us bad data!
141  */
142 unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
143 {
144         struct siginfo si;
145         void *catcher;
146         int err;
147         int is_write = FAULT_WRITE(fi);
148         unsigned long address = FAULT_ADDRESS(fi);
149
150         if(!is_user && (address >= start_vm) && (address < end_vm)){
151                 flush_tlb_kernel_vm();
152                 return(0);
153         }
154         else if(check_remapped_addr(address & PAGE_MASK, is_write))
155                 return(0);
156         else if(current->mm == NULL)
157                 panic("Segfault with no mm");
158         err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
159
160         catcher = current->thread.fault_catcher;
161         if(!err)
162                 return(0);
163         else if(catcher != NULL){
164                 current->thread.fault_addr = (void *) address;
165                 do_longjmp(catcher, 1);
166         } 
167         else if(current->thread.fault_addr != NULL)
168                 panic("fault_addr set but no fault catcher");
169         else if(!is_user && arch_fixup(ip, sc))
170                 return(0);
171
172         if(!is_user) 
173                 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx", 
174                       address, ip);
175
176         if(err == -EACCES){
177                 si.si_signo = SIGBUS;
178                 si.si_errno = 0;
179                 si.si_code = BUS_ADRERR;
180                 si.si_addr = (void *)address;
181                 current->thread.arch.faultinfo = fi;
182                 force_sig_info(SIGBUS, &si, current);
183         }
184         else if(err == -ENOMEM){
185                 printk("VM: killing process %s\n", current->comm);
186                 do_exit(SIGKILL);
187         }
188         else {
189                 si.si_signo = SIGSEGV;
190                 si.si_addr = (void *) address;
191                 current->thread.arch.faultinfo = fi;
192                 force_sig_info(SIGSEGV, &si, current);
193         }
194         return(0);
195 }
196
197 void bad_segv(struct faultinfo fi, unsigned long ip)
198 {
199         struct siginfo si;
200
201         si.si_signo = SIGSEGV;
202         si.si_code = SEGV_ACCERR;
203         si.si_addr = (void *) FAULT_ADDRESS(fi);
204         current->thread.arch.faultinfo = fi;
205         force_sig_info(SIGSEGV, &si, current);
206 }
207
208 void relay_signal(int sig, union uml_pt_regs *regs)
209 {
210         if(arch_handle_signal(sig, regs)) return;
211         if(!UPT_IS_USER(regs))
212                 panic("Kernel mode signal %d", sig);
213         current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
214         force_sig(sig, current);
215 }
216
217 void bus_handler(int sig, union uml_pt_regs *regs)
218 {
219         if(current->thread.fault_catcher != NULL)
220                 do_longjmp(current->thread.fault_catcher, 1);
221         else relay_signal(sig, regs);
222 }
223
224 void winch(int sig, union uml_pt_regs *regs)
225 {
226         do_IRQ(WINCH_IRQ, regs);
227 }
228
229 void trap_init(void)
230 {
231 }
232
233 DEFINE_SPINLOCK(trap_lock);
234
235 static int trap_index = 0;
236
237 int next_trap_index(int limit)
238 {
239         int ret;
240
241         spin_lock(&trap_lock);
242         ret = trap_index;
243         if(++trap_index == limit)
244                 trap_index = 0;
245         spin_unlock(&trap_lock);
246         return(ret);
247 }
248
249 /*
250  * Overrides for Emacs so that we follow Linus's tabbing style.
251  * Emacs will notice this stuff at the end of the file and automatically
252  * adjust the settings for this buffer only.  This must remain at the end
253  * of the file.
254  * ---------------------------------------------------------------------------
255  * Local variables:
256  * c-file-style: "linux"
257  * End:
258  */