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/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"
21 #include "sysdep/sigcontext.h"
22 #include "user_util.h"
23 #include "kern_util.h"
25 #include "chan_kern.h"
26 #include "mconsole_kern.h"
30 /* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
31 int handle_page_fault(unsigned long address, unsigned long ip,
32 int is_write, int is_user, int *code_out)
34 struct mm_struct *mm = current->mm;
35 struct vm_area_struct *vma;
42 *code_out = SEGV_MAPERR;
44 /* If the fault was during atomic operation, don't take the fault, just
49 down_read(&mm->mmap_sem);
50 vma = find_vma(mm, address);
53 else if(vma->vm_start <= address)
55 else if(!(vma->vm_flags & VM_GROWSDOWN))
57 else if(is_user && !ARCH_IS_STACKGROW(address))
59 else if(expand_stack(vma, address))
63 *code_out = SEGV_ACCERR;
64 if(is_write && !(vma->vm_flags & VM_WRITE))
67 /* Don't require VM_READ|VM_EXEC for write faults! */
68 if(!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
73 switch (handle_mm_fault(mm, vma, address, is_write)){
89 pgd = pgd_offset(mm, address);
90 pud = pud_offset(pgd, address);
91 pmd = pmd_offset(pud, address);
92 pte = pte_offset_kernel(pmd, address);
93 } while(!pte_present(*pte));
95 WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
96 flush_tlb_page(vma, address);
98 up_read(&mm->mmap_sem);
103 * We ran out of memory, or some other thing happened to us that made
104 * us unable to handle the page fault gracefully.
107 if (current->pid == 1) {
108 up_read(&mm->mmap_sem);
110 down_read(&mm->mmap_sem);
117 * We give a *copy* of the faultinfo in the regs to segv.
118 * This must be done, since nesting SEGVs could overwrite
119 * the info in the regs. A pointer to the info then would
122 unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
127 int is_write = FAULT_WRITE(fi);
128 unsigned long address = FAULT_ADDRESS(fi);
130 if(!is_user && (address >= start_vm) && (address < end_vm)){
131 flush_tlb_kernel_vm();
134 else if(current->mm == NULL)
135 panic("Segfault with no mm");
137 if (SEGV_IS_FIXABLE(&fi))
138 err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
141 /* A thread accessed NULL, we get a fault, but CR2 is invalid.
142 * This code is used in __do_copy_from_user() of TT mode. */
146 catcher = current->thread.fault_catcher;
149 else if(catcher != NULL){
150 current->thread.fault_addr = (void *) address;
151 do_longjmp(catcher, 1);
153 else if(current->thread.fault_addr != NULL)
154 panic("fault_addr set but no fault catcher");
155 else if(!is_user && arch_fixup(ip, sc))
159 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
162 if (err == -EACCES) {
163 si.si_signo = SIGBUS;
165 si.si_code = BUS_ADRERR;
166 si.si_addr = (void *)address;
167 current->thread.arch.faultinfo = fi;
168 force_sig_info(SIGBUS, &si, current);
169 } else if (err == -ENOMEM) {
170 printk("VM: killing process %s\n", current->comm);
173 BUG_ON(err != -EFAULT);
174 si.si_signo = SIGSEGV;
175 si.si_addr = (void *) address;
176 current->thread.arch.faultinfo = fi;
177 force_sig_info(SIGSEGV, &si, current);
182 void bad_segv(struct faultinfo fi, unsigned long ip)
186 si.si_signo = SIGSEGV;
187 si.si_code = SEGV_ACCERR;
188 si.si_addr = (void *) FAULT_ADDRESS(fi);
189 current->thread.arch.faultinfo = fi;
190 force_sig_info(SIGSEGV, &si, current);
193 void relay_signal(int sig, union uml_pt_regs *regs)
195 if(arch_handle_signal(sig, regs)) return;
196 if(!UPT_IS_USER(regs))
197 panic("Kernel mode signal %d", sig);
198 current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
199 force_sig(sig, current);
202 void bus_handler(int sig, union uml_pt_regs *regs)
204 if(current->thread.fault_catcher != NULL)
205 do_longjmp(current->thread.fault_catcher, 1);
206 else relay_signal(sig, regs);
209 void winch(int sig, union uml_pt_regs *regs)
211 do_IRQ(WINCH_IRQ, regs);