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 "user_util.h"
22 #include "kern_util.h"
23 #include "as-layout.h"
26 #include "chan_kern.h"
27 #include "mconsole_kern.h"
30 #include "sysdep/sigcontext.h"
31 #include "sysdep/ptrace.h"
33 #ifdef CONFIG_MODE_SKAS
38 /* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
39 int handle_page_fault(unsigned long address, unsigned long ip,
40 int is_write, int is_user, int *code_out)
42 struct mm_struct *mm = current->mm;
43 struct vm_area_struct *vma;
50 *code_out = SEGV_MAPERR;
52 /* If the fault was during atomic operation, don't take the fault, just
57 down_read(&mm->mmap_sem);
58 vma = find_vma(mm, address);
61 else if(vma->vm_start <= address)
63 else if(!(vma->vm_flags & VM_GROWSDOWN))
65 else if(is_user && !ARCH_IS_STACKGROW(address))
67 else if(expand_stack(vma, address))
71 *code_out = SEGV_ACCERR;
72 if(is_write && !(vma->vm_flags & VM_WRITE))
75 /* Don't require VM_READ|VM_EXEC for write faults! */
76 if(!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
81 switch (handle_mm_fault(mm, vma, address, is_write)){
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, void *sc)
166 int is_write = FAULT_WRITE(fi);
167 unsigned long address = FAULT_ADDRESS(fi);
169 if(!is_user && (address >= start_vm) && (address < end_vm)){
170 flush_tlb_kernel_vm();
173 else if(current->mm == NULL)
174 panic("Segfault with no mm");
176 if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
177 err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
180 /* A thread accessed NULL, we get a fault, but CR2 is invalid.
181 * This code is used in __do_copy_from_user() of TT mode. */
185 catcher = current->thread.fault_catcher;
188 else if(catcher != NULL){
189 current->thread.fault_addr = (void *) address;
190 do_longjmp(catcher, 1);
192 else if(current->thread.fault_addr != NULL)
193 panic("fault_addr set but no fault catcher");
194 else if(!is_user && arch_fixup(ip, sc))
198 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
201 if (err == -EACCES) {
202 si.si_signo = SIGBUS;
204 si.si_code = BUS_ADRERR;
205 si.si_addr = (void __user *)address;
206 current->thread.arch.faultinfo = fi;
207 force_sig_info(SIGBUS, &si, current);
208 } else if (err == -ENOMEM) {
209 printk("VM: killing process %s\n", current->comm);
212 BUG_ON(err != -EFAULT);
213 si.si_signo = SIGSEGV;
214 si.si_addr = (void __user *) address;
215 current->thread.arch.faultinfo = fi;
216 force_sig_info(SIGSEGV, &si, current);
221 void relay_signal(int sig, union uml_pt_regs *regs)
223 if(arch_handle_signal(sig, regs))
226 if(!UPT_IS_USER(regs)){
228 printk("Bus error - the /dev/shm or /tmp mount likely "
229 "just ran out of space\n");
230 panic("Kernel mode signal %d", sig);
233 current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
234 force_sig(sig, current);
237 static void bus_handler(int sig, union uml_pt_regs *regs)
239 if(current->thread.fault_catcher != NULL)
240 do_longjmp(current->thread.fault_catcher, 1);
241 else relay_signal(sig, regs);
244 static void winch(int sig, union uml_pt_regs *regs)
246 do_IRQ(WINCH_IRQ, regs);
249 const struct kern_handlers handlinfo_kern = {
250 .relay_signal = relay_signal,
252 .bus_handler = bus_handler,
253 .page_fault = segv_handler,
254 .sigio_handler = sigio_handler,
255 .timer_handler = timer_handler