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"
29 #ifdef CONFIG_MODE_SKAS
33 /* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
34 int handle_page_fault(unsigned long address, unsigned long ip,
35 int is_write, int is_user, int *code_out)
37 struct mm_struct *mm = current->mm;
38 struct vm_area_struct *vma;
45 *code_out = SEGV_MAPERR;
47 /* If the fault was during atomic operation, don't take the fault, just
52 down_read(&mm->mmap_sem);
53 vma = find_vma(mm, address);
56 else if(vma->vm_start <= address)
58 else if(!(vma->vm_flags & VM_GROWSDOWN))
60 else if(is_user && !ARCH_IS_STACKGROW(address))
62 else if(expand_stack(vma, address))
66 *code_out = SEGV_ACCERR;
67 if(is_write && !(vma->vm_flags & VM_WRITE))
70 /* Don't require VM_READ|VM_EXEC for write faults! */
71 if(!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
76 switch (handle_mm_fault(mm, vma, address, is_write)){
92 pgd = pgd_offset(mm, address);
93 pud = pud_offset(pgd, address);
94 pmd = pmd_offset(pud, address);
95 pte = pte_offset_kernel(pmd, address);
96 } while(!pte_present(*pte));
98 WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
99 flush_tlb_page(vma, address);
101 up_read(&mm->mmap_sem);
106 * We ran out of memory, or some other thing happened to us that made
107 * us unable to handle the page fault gracefully.
110 if (current->pid == 1) {
111 up_read(&mm->mmap_sem);
113 down_read(&mm->mmap_sem);
120 * We give a *copy* of the faultinfo in the regs to segv.
121 * This must be done, since nesting SEGVs could overwrite
122 * the info in the regs. A pointer to the info then would
125 unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
130 int is_write = FAULT_WRITE(fi);
131 unsigned long address = FAULT_ADDRESS(fi);
133 if(!is_user && (address >= start_vm) && (address < end_vm)){
134 flush_tlb_kernel_vm();
137 else if(current->mm == NULL)
138 panic("Segfault with no mm");
140 if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
141 err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
144 /* A thread accessed NULL, we get a fault, but CR2 is invalid.
145 * This code is used in __do_copy_from_user() of TT mode. */
149 catcher = current->thread.fault_catcher;
152 else if(catcher != NULL){
153 current->thread.fault_addr = (void *) address;
154 do_longjmp(catcher, 1);
156 else if(current->thread.fault_addr != NULL)
157 panic("fault_addr set but no fault catcher");
158 else if(!is_user && arch_fixup(ip, sc))
162 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
165 if (err == -EACCES) {
166 si.si_signo = SIGBUS;
168 si.si_code = BUS_ADRERR;
169 si.si_addr = (void *)address;
170 current->thread.arch.faultinfo = fi;
171 force_sig_info(SIGBUS, &si, current);
172 } else if (err == -ENOMEM) {
173 printk("VM: killing process %s\n", current->comm);
176 BUG_ON(err != -EFAULT);
177 si.si_signo = SIGSEGV;
178 si.si_addr = (void *) address;
179 current->thread.arch.faultinfo = fi;
180 force_sig_info(SIGSEGV, &si, current);
185 void bad_segv(struct faultinfo fi, unsigned long ip)
189 si.si_signo = SIGSEGV;
190 si.si_code = SEGV_ACCERR;
191 si.si_addr = (void *) FAULT_ADDRESS(fi);
192 current->thread.arch.faultinfo = fi;
193 force_sig_info(SIGSEGV, &si, current);
196 void relay_signal(int sig, union uml_pt_regs *regs)
198 if(arch_handle_signal(sig, regs)) return;
199 if(!UPT_IS_USER(regs))
200 panic("Kernel mode signal %d", sig);
201 current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
202 force_sig(sig, current);
205 void bus_handler(int sig, union uml_pt_regs *regs)
207 if(current->thread.fault_catcher != NULL)
208 do_longjmp(current->thread.fault_catcher, 1);
209 else relay_signal(sig, regs);
212 void winch(int sig, union uml_pt_regs *regs)
214 do_IRQ(WINCH_IRQ, regs);