]> nv-tegra.nvidia Code Review - linux-3.10.git/blob - arch/um/kernel/trap_kern.c
[PATCH] uml: Page fault fixes
[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
61         if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
62                 goto out;
63
64         page = address & PAGE_MASK;
65         do {
66  survive:
67                 switch (handle_mm_fault(mm, vma, address, is_write)){
68                 case VM_FAULT_MINOR:
69                         current->min_flt++;
70                         break;
71                 case VM_FAULT_MAJOR:
72                         current->maj_flt++;
73                         break;
74                 case VM_FAULT_SIGBUS:
75                         err = -EACCES;
76                         goto out;
77                 case VM_FAULT_OOM:
78                         err = -ENOMEM;
79                         goto out_of_memory;
80                 default:
81                         BUG();
82                 }
83                 pgd = pgd_offset(mm, page);
84                 pud = pud_offset(pgd, page);
85                 pmd = pmd_offset(pud, page);
86                 pte = pte_offset_kernel(pmd, page);
87         } while(!pte_present(*pte));
88         err = 0;
89         *pte = pte_mkyoung(*pte);
90         if(pte_write(*pte)) *pte = pte_mkdirty(*pte);
91         flush_tlb_page(vma, page);
92  out:
93         up_read(&mm->mmap_sem);
94         return(err);
95
96 /*
97  * We ran out of memory, or some other thing happened to us that made
98  * us unable to handle the page fault gracefully.
99  */
100 out_of_memory:
101         if (current->pid == 1) {
102                 up_read(&mm->mmap_sem);
103                 yield();
104                 down_read(&mm->mmap_sem);
105                 goto survive;
106         }
107         goto out;
108 }
109
110 LIST_HEAD(physmem_remappers);
111
112 void register_remapper(struct remapper *info)
113 {
114         list_add(&info->list, &physmem_remappers);
115 }
116
117 static int check_remapped_addr(unsigned long address, int is_write)
118 {
119         struct remapper *remapper;
120         struct list_head *ele;
121         __u64 offset;
122         int fd;
123
124         fd = phys_mapping(__pa(address), &offset);
125         if(fd == -1)
126                 return(0);
127
128         list_for_each(ele, &physmem_remappers){
129                 remapper = list_entry(ele, struct remapper, list);
130                 if((*remapper->proc)(fd, address, is_write, offset))
131                         return(1);
132         }
133
134         return(0);
135 }
136
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)
144 {
145         struct siginfo si;
146         void *catcher;
147         int err;
148         int is_write = FAULT_WRITE(fi);
149         unsigned long address = FAULT_ADDRESS(fi);
150
151         if(!is_user && (address >= start_vm) && (address < end_vm)){
152                 flush_tlb_kernel_vm();
153                 return(0);
154         }
155         else if(check_remapped_addr(address & PAGE_MASK, is_write))
156                 return(0);
157         else if(current->mm == NULL)
158                 panic("Segfault with no mm");
159         err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
160
161         catcher = current->thread.fault_catcher;
162         if(!err)
163                 return(0);
164         else if(catcher != NULL){
165                 current->thread.fault_addr = (void *) address;
166                 do_longjmp(catcher, 1);
167         } 
168         else if(current->thread.fault_addr != NULL)
169                 panic("fault_addr set but no fault catcher");
170         else if(!is_user && arch_fixup(ip, sc))
171                 return(0);
172
173         if(!is_user) 
174                 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx", 
175                       address, ip);
176
177         if(err == -EACCES){
178                 si.si_signo = SIGBUS;
179                 si.si_errno = 0;
180                 si.si_code = BUS_ADRERR;
181                 si.si_addr = (void *)address;
182                 current->thread.arch.faultinfo = fi;
183                 force_sig_info(SIGBUS, &si, current);
184         }
185         else if(err == -ENOMEM){
186                 printk("VM: killing process %s\n", current->comm);
187                 do_exit(SIGKILL);
188         }
189         else {
190                 si.si_signo = SIGSEGV;
191                 si.si_addr = (void *) address;
192                 current->thread.arch.faultinfo = fi;
193                 force_sig_info(SIGSEGV, &si, current);
194         }
195         return(0);
196 }
197
198 void bad_segv(struct faultinfo fi, unsigned long ip)
199 {
200         struct siginfo si;
201
202         si.si_signo = SIGSEGV;
203         si.si_code = SEGV_ACCERR;
204         si.si_addr = (void *) FAULT_ADDRESS(fi);
205         current->thread.arch.faultinfo = fi;
206         force_sig_info(SIGSEGV, &si, current);
207 }
208
209 void relay_signal(int sig, union uml_pt_regs *regs)
210 {
211         if(arch_handle_signal(sig, regs)) return;
212         if(!UPT_IS_USER(regs))
213                 panic("Kernel mode signal %d", sig);
214         current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
215         force_sig(sig, current);
216 }
217
218 void bus_handler(int sig, union uml_pt_regs *regs)
219 {
220         if(current->thread.fault_catcher != NULL)
221                 do_longjmp(current->thread.fault_catcher, 1);
222         else relay_signal(sig, regs);
223 }
224
225 void winch(int sig, union uml_pt_regs *regs)
226 {
227         do_IRQ(WINCH_IRQ, regs);
228 }
229
230 void trap_init(void)
231 {
232 }
233
234 DEFINE_SPINLOCK(trap_lock);
235
236 static int trap_index = 0;
237
238 int next_trap_index(int limit)
239 {
240         int ret;
241
242         spin_lock(&trap_lock);
243         ret = trap_index;
244         if(++trap_index == limit)
245                 trap_index = 0;
246         spin_unlock(&trap_lock);
247         return(ret);
248 }
249
250 /*
251  * Overrides for Emacs so that we follow Linus's tabbing style.
252  * Emacs will notice this stuff at the end of the file and automatically
253  * adjust the settings for this buffer only.  This must remain at the end
254  * of the file.
255  * ---------------------------------------------------------------------------
256  * Local variables:
257  * c-file-style: "linux"
258  * End:
259  */