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/*
* linux/arch/alpha/mm/fault.c
*
* Copyright (C) 1995 Linus Torvalds
*/
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/head.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>
unsigned long asn_cache = ASN_FIRST_VERSION;
#ifndef BROKEN_ASN
/*
* Select a new ASN and reload the context. This is
* not inlined as this expands to a pretty large
* function.
*/
void get_new_asn_and_reload(struct task_struct *tsk, struct mm_struct *mm)
{
get_new_mmu_context(tsk, mm, asn_cache);
reload_context(tsk);
}
#endif
extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *);
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to handle_mm_fault().
*
* mmcsr:
* 0 = translation not valid
* 1 = access violation
* 2 = fault-on-read
* 3 = fault-on-execute
* 4 = fault-on-write
*
* cause:
* -1 = instruction fetch
* 0 = load
* 1 = store
*
* Registers $9 through $15 are saved in a block just prior to `regs' and
* are saved and restored around the call to allow exception code to
* modify them.
*/
/* Macro for exception fixup code to access integer registers. */
#define dpf_reg(r) \
(((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \
(r) <= 18 ? (r)+8 : (r)-10])
asmlinkage void do_page_fault(unsigned long address, unsigned long mmcsr,
long cause, struct pt_regs *regs)
{
struct vm_area_struct * vma;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
unsigned fixup;
down(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
if (cause < 0) {
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
} else if (!cause) {
/* Allow reads even for write-only mappings */
if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
goto bad_area;
} else {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
}
handle_mm_fault(vma, address, cause > 0);
up(&mm->mmap_sem);
return;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up(&mm->mmap_sem);
/* Are we prepared to handle this fault as an exception? */
if ((fixup = search_exception_table(regs->pc)) != 0) {
unsigned long newpc;
newpc = fixup_exception(dpf_reg, fixup, regs->pc);
printk("Taking exception at [<%lx>] (%lx)\n", regs->pc, newpc);
regs->pc = newpc;
return;
}
if (user_mode(regs)) {
printk("%s: memory violation at pc=%08lx ra=%08lx "
"(bad address = %08lx)\n",
tsk->comm, regs->pc, regs->r26, address);
die_if_kernel("oops", regs, cause, (unsigned long*)regs - 16);
force_sig(SIGSEGV, tsk);
return;
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
printk(KERN_ALERT "Unable to handle kernel paging request at "
"virtual address %016lx\n", address);
die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16);
do_exit(SIGKILL);
}
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