Pull esi-support into release branch
[linux-2.6] / arch / um / kernel / trap.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 "sysdep/sigcontext.h"
22 #include "user_util.h"
23 #include "kern_util.h"
24 #include "kern.h"
25 #include "chan_kern.h"
26 #include "mconsole_kern.h"
27 #include "mem.h"
28 #include "mem_kern.h"
29 #include "sysdep/sigcontext.h"
30 #include "sysdep/ptrace.h"
31 #include "os.h"
32 #ifdef CONFIG_MODE_SKAS
33 #include "skas.h"
34 #endif
35 #include "os.h"
36
37 /* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
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;
47         int err = -EFAULT;
48
49         *code_out = SEGV_MAPERR;
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
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;
64         else if(is_user && !ARCH_IS_STACKGROW(address))
65                 goto out;
66         else if(expand_stack(vma, address))
67                 goto out;
68
69 good_area:
70         *code_out = SEGV_ACCERR;
71         if(is_write && !(vma->vm_flags & VM_WRITE))
72                 goto out;
73
74         /* Don't require VM_READ|VM_EXEC for write faults! */
75         if(!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
76                 goto out;
77
78         do {
79 survive:
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                 }
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);
100         } while(!pte_present(*pte));
101         err = 0;
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
110         WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
111 #endif
112         flush_tlb_page(vma, address);
113 out:
114         up_read(&mm->mmap_sem);
115 out_nosemaphore:
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
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
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 };
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)
158 {
159         struct siginfo si;
160         void *catcher;
161         int err;
162         int is_write = FAULT_WRITE(fi);
163         unsigned long address = FAULT_ADDRESS(fi);
164
165         if(!is_user && (address >= start_vm) && (address < end_vm)){
166                 flush_tlb_kernel_vm();
167                 return(0);
168         }
169         else if(current->mm == NULL)
170                 panic("Segfault with no mm");
171
172         if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
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         }
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");
190         else if(!is_user && arch_fixup(ip, sc))
191                 return(0);
192
193         if(!is_user)
194                 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
195                       address, ip);
196
197         if (err == -EACCES) {
198                 si.si_signo = SIGBUS;
199                 si.si_errno = 0;
200                 si.si_code = BUS_ADRERR;
201                 si.si_addr = (void __user *)address;
202                 current->thread.arch.faultinfo = fi;
203                 force_sig_info(SIGBUS, &si, current);
204         } else if (err == -ENOMEM) {
205                 printk("VM: killing process %s\n", current->comm);
206                 do_exit(SIGKILL);
207         } else {
208                 BUG_ON(err != -EFAULT);
209                 si.si_signo = SIGSEGV;
210                 si.si_addr = (void __user *) address;
211                 current->thread.arch.faultinfo = fi;
212                 force_sig_info(SIGSEGV, &si, current);
213         }
214         return(0);
215 }
216
217 void bad_segv(struct faultinfo fi, unsigned long ip)
218 {
219         struct siginfo si;
220
221         si.si_signo = SIGSEGV;
222         si.si_code = SEGV_ACCERR;
223         si.si_addr = (void __user *) FAULT_ADDRESS(fi);
224         current->thread.arch.faultinfo = fi;
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);
233         current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
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 }