2 * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
3 * Licensed under the GPL
6 #include "linux/kernel.h"
8 #include "linux/sched.h"
10 #include "linux/spinlock.h"
11 #include "linux/init.h"
12 #include "linux/ptrace.h"
13 #include "asm/semaphore.h"
14 #include "asm/pgtable.h"
15 #include "asm/pgalloc.h"
16 #include "asm/tlbflush.h"
17 #include "asm/a.out.h"
18 #include "asm/current.h"
20 #include "sysdep/sigcontext.h"
21 #include "kern_util.h"
22 #include "as-layout.h"
25 #include "chan_kern.h"
26 #include "mconsole_kern.h"
29 #include "sysdep/sigcontext.h"
30 #include "sysdep/ptrace.h"
32 #ifdef CONFIG_MODE_SKAS
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
)
41 struct mm_struct
*mm
= current
->mm
;
42 struct vm_area_struct
*vma
;
49 *code_out
= SEGV_MAPERR
;
51 /* If the fault was during atomic operation, don't take the fault, just
56 down_read(&mm
->mmap_sem
);
57 vma
= find_vma(mm
, address
);
60 else if(vma
->vm_start
<= address
)
62 else if(!(vma
->vm_flags
& VM_GROWSDOWN
))
64 else if(is_user
&& !ARCH_IS_STACKGROW(address
))
66 else if(expand_stack(vma
, address
))
70 *code_out
= SEGV_ACCERR
;
71 if(is_write
&& !(vma
->vm_flags
& VM_WRITE
))
74 /* Don't require VM_READ|VM_EXEC for write faults! */
75 if(!is_write
&& !(vma
->vm_flags
& (VM_READ
| VM_EXEC
)))
81 fault
= handle_mm_fault(mm
, vma
, address
, is_write
);
82 if (unlikely(fault
& VM_FAULT_ERROR
)) {
83 if (fault
& VM_FAULT_OOM
) {
86 } else if (fault
& VM_FAULT_SIGBUS
) {
92 if (fault
& VM_FAULT_MAJOR
)
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
);
101 } while(!pte_present(*pte
));
103 /* The below warning was added in place of
104 * pte_mkyoung(); if (is_write) pte_mkdirty();
105 * If it's triggered, we'd see normally a hang here (a clean pte is
106 * marked read-only to emulate the dirty bit).
107 * However, the generic code can mark a PTE writable but clean on a
108 * concurrent read fault, triggering this harmlessly. So comment it out.
111 WARN_ON(!pte_young(*pte
) || (is_write
&& !pte_dirty(*pte
)));
113 flush_tlb_page(vma
, address
);
115 up_read(&mm
->mmap_sem
);
120 * We ran out of memory, or some other thing happened to us that made
121 * us unable to handle the page fault gracefully.
124 if (is_init(current
)) {
125 up_read(&mm
->mmap_sem
);
127 down_read(&mm
->mmap_sem
);
133 static void bad_segv(struct faultinfo fi
, unsigned long ip
)
137 si
.si_signo
= SIGSEGV
;
138 si
.si_code
= SEGV_ACCERR
;
139 si
.si_addr
= (void __user
*) FAULT_ADDRESS(fi
);
140 current
->thread
.arch
.faultinfo
= fi
;
141 force_sig_info(SIGSEGV
, &si
, current
);
144 static void segv_handler(int sig
, union uml_pt_regs
*regs
)
146 struct faultinfo
* fi
= UPT_FAULTINFO(regs
);
148 if(UPT_IS_USER(regs
) && !SEGV_IS_FIXABLE(fi
)){
149 bad_segv(*fi
, UPT_IP(regs
));
152 segv(*fi
, UPT_IP(regs
), UPT_IS_USER(regs
), regs
);
156 * We give a *copy* of the faultinfo in the regs to segv.
157 * This must be done, since nesting SEGVs could overwrite
158 * the info in the regs. A pointer to the info then would
161 unsigned long segv(struct faultinfo fi
, unsigned long ip
, int is_user
,
162 union uml_pt_regs
*regs
)
167 int is_write
= FAULT_WRITE(fi
);
168 unsigned long address
= FAULT_ADDRESS(fi
);
170 if(!is_user
&& (address
>= start_vm
) && (address
< end_vm
)){
171 flush_tlb_kernel_vm();
174 else if(current
->mm
== NULL
) {
175 show_regs(container_of(regs
, struct pt_regs
, regs
));
176 panic("Segfault with no mm");
179 if (SEGV_IS_FIXABLE(&fi
) || SEGV_MAYBE_FIXABLE(&fi
))
180 err
= handle_page_fault(address
, ip
, is_write
, is_user
, &si
.si_code
);
183 /* A thread accessed NULL, we get a fault, but CR2 is invalid.
184 * This code is used in __do_copy_from_user() of TT mode. */
188 catcher
= current
->thread
.fault_catcher
;
191 else if(catcher
!= NULL
){
192 current
->thread
.fault_addr
= (void *) address
;
193 do_longjmp(catcher
, 1);
195 else if(current
->thread
.fault_addr
!= NULL
)
196 panic("fault_addr set but no fault catcher");
197 else if(!is_user
&& arch_fixup(ip
, regs
))
201 show_regs(container_of(regs
, struct pt_regs
, regs
));
202 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
206 if (err
== -EACCES
) {
207 si
.si_signo
= SIGBUS
;
209 si
.si_code
= BUS_ADRERR
;
210 si
.si_addr
= (void __user
*)address
;
211 current
->thread
.arch
.faultinfo
= fi
;
212 force_sig_info(SIGBUS
, &si
, current
);
213 } else if (err
== -ENOMEM
) {
214 printk("VM: killing process %s\n", current
->comm
);
217 BUG_ON(err
!= -EFAULT
);
218 si
.si_signo
= SIGSEGV
;
219 si
.si_addr
= (void __user
*) address
;
220 current
->thread
.arch
.faultinfo
= fi
;
221 force_sig_info(SIGSEGV
, &si
, current
);
226 void relay_signal(int sig
, union uml_pt_regs
*regs
)
228 if(arch_handle_signal(sig
, regs
))
231 if(!UPT_IS_USER(regs
)){
233 printk("Bus error - the host /dev/shm or /tmp mount "
234 "likely just ran out of space\n");
235 panic("Kernel mode signal %d", sig
);
238 current
->thread
.arch
.faultinfo
= *UPT_FAULTINFO(regs
);
239 force_sig(sig
, current
);
242 static void bus_handler(int sig
, union uml_pt_regs
*regs
)
244 if(current
->thread
.fault_catcher
!= NULL
)
245 do_longjmp(current
->thread
.fault_catcher
, 1);
246 else relay_signal(sig
, regs
);
249 static void winch(int sig
, union uml_pt_regs
*regs
)
251 do_IRQ(WINCH_IRQ
, regs
);
254 const struct kern_handlers handlinfo_kern
= {
255 .relay_signal
= relay_signal
,
257 .bus_handler
= bus_handler
,
258 .page_fault
= segv_handler
,
259 .sigio_handler
= sigio_handler
,
260 .timer_handler
= timer_handler