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)))
80 switch (handle_mm_fault(mm, vma, address, is_write)){
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));
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.
110 WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
112 flush_tlb_page(vma, address);
114 up_read(&mm->mmap_sem);
119 * We ran out of memory, or some other thing happened to us that made
120 * us unable to handle the page fault gracefully.
123 if (is_init(current)) {
124 up_read(&mm->mmap_sem);
126 down_read(&mm->mmap_sem);
132 static void bad_segv(struct faultinfo fi, unsigned long ip)
136 si.si_signo = SIGSEGV;
137 si.si_code = SEGV_ACCERR;
138 si.si_addr = (void __user *) FAULT_ADDRESS(fi);
139 current->thread.arch.faultinfo = fi;
140 force_sig_info(SIGSEGV, &si, current);
143 static void segv_handler(int sig, union uml_pt_regs *regs)
145 struct faultinfo * fi = UPT_FAULTINFO(regs);
147 if(UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)){
148 bad_segv(*fi, UPT_IP(regs));
151 segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs);
155 * We give a *copy* of the faultinfo in the regs to segv.
156 * This must be done, since nesting SEGVs could overwrite
157 * the info in the regs. A pointer to the info then would
160 unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
165 int is_write = FAULT_WRITE(fi);
166 unsigned long address = FAULT_ADDRESS(fi);
168 if(!is_user && (address >= start_vm) && (address < end_vm)){
169 flush_tlb_kernel_vm();
172 else if(current->mm == NULL)
173 panic("Segfault with no mm");
175 if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
176 err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
179 /* A thread accessed NULL, we get a fault, but CR2 is invalid.
180 * This code is used in __do_copy_from_user() of TT mode. */
184 catcher = current->thread.fault_catcher;
187 else if(catcher != NULL){
188 current->thread.fault_addr = (void *) address;
189 do_longjmp(catcher, 1);
191 else if(current->thread.fault_addr != NULL)
192 panic("fault_addr set but no fault catcher");
193 else if(!is_user && arch_fixup(ip, sc))
197 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
200 if (err == -EACCES) {
201 si.si_signo = SIGBUS;
203 si.si_code = BUS_ADRERR;
204 si.si_addr = (void __user *)address;
205 current->thread.arch.faultinfo = fi;
206 force_sig_info(SIGBUS, &si, current);
207 } else if (err == -ENOMEM) {
208 printk("VM: killing process %s\n", current->comm);
211 BUG_ON(err != -EFAULT);
212 si.si_signo = SIGSEGV;
213 si.si_addr = (void __user *) address;
214 current->thread.arch.faultinfo = fi;
215 force_sig_info(SIGSEGV, &si, current);
220 void relay_signal(int sig, union uml_pt_regs *regs)
222 if(arch_handle_signal(sig, regs))
225 if(!UPT_IS_USER(regs)){
227 printk("Bus error - the /dev/shm or /tmp mount likely "
228 "just ran out of space\n");
229 panic("Kernel mode signal %d", sig);
232 current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
233 force_sig(sig, current);
236 static void bus_handler(int sig, union uml_pt_regs *regs)
238 if(current->thread.fault_catcher != NULL)
239 do_longjmp(current->thread.fault_catcher, 1);
240 else relay_signal(sig, regs);
243 static void winch(int sig, union uml_pt_regs *regs)
245 do_IRQ(WINCH_IRQ, regs);
248 const struct kern_handlers handlinfo_kern = {
249 .relay_signal = relay_signal,
251 .bus_handler = bus_handler,
252 .page_fault = segv_handler,
253 .sigio_handler = sigio_handler,
254 .timer_handler = timer_handler