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/*
* arch/s390/mm/fault.c
*
* S390 version
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Hartmut Penner (hp@de.ibm.com)
*
* Derived from "arch/i386/mm/fault.c"
* Copyright (C) 1995 Linus Torvalds
*/
#include <linux/config.h>
#include <linux/signal.h>
#include <linux/sched.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 <linux/smp.h>
#include <linux/smp_lock.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/hardirq.h>
#ifdef CONFIG_SYSCTL
extern int sysctl_userprocess_debug;
#endif
extern void die(const char *,struct pt_regs *,long);
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*
* error_code:
* ****0004 Protection -> Write-Protection (suprression)
* ****0010 Segment translation -> Not present (nullification)
* ****0011 Page translation -> Not present (nullification)
* ****003B Region third exception -> Not present (nullification)
*/
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct * vma;
unsigned long address;
unsigned long fixup;
int write;
unsigned long psw_mask;
unsigned long psw_addr;
int si_code = SEGV_MAPERR;
int kernel_address = 0;
/*
* get psw mask of Program old psw to find out,
* if user or kernel mode
*/
psw_mask = S390_lowcore.program_old_psw.mask;
psw_addr = S390_lowcore.program_old_psw.addr;
/*
* get the failing address
* more specific the segment and page table portion of
* the address
*/
address = S390_lowcore.trans_exc_code&-4096L;
tsk = current;
mm = tsk->mm;
if (in_interrupt() || !mm)
goto no_context;
/*
* Check which address space the address belongs to
*/
switch (S390_lowcore.trans_exc_code & 3)
{
case 0: /* Primary Segment Table Descriptor */
kernel_address = 1;
goto no_context;
case 1: /* STD determined via access register */
if (S390_lowcore.exc_access_id == 0)
{
kernel_address = 1;
goto no_context;
}
if (regs && S390_lowcore.exc_access_id < NUM_ACRS)
{
if (regs->acrs[S390_lowcore.exc_access_id] == 0)
{
kernel_address = 1;
goto no_context;
}
if (regs->acrs[S390_lowcore.exc_access_id] == 1)
{
/* user space address */
break;
}
}
die("page fault via unknown access register", regs, error_code);
break;
case 2: /* Secondary Segment Table Descriptor */
case 3: /* Home Segment Table Descriptor */
/* user space address */
break;
}
/*
* When we get here, the fault happened in the current
* task's user address space, so we search the VMAs
*/
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma) {
printk("no vma for address %lX\n",address);
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:
write = 0;
si_code = SEGV_ACCERR;
switch (error_code & 0xFF) {
case 0x04: /* write, present*/
write = 1;
break;
case 0x10: /* not present*/
case 0x11: /* not present*/
case 0x3B: /* not present*/
if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
goto bad_area;
break;
default:
printk("code should be 4, 10 or 11 (%lX) \n",error_code&0xFF);
goto bad_area;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
switch (handle_mm_fault(mm, vma, address, write)) {
case 1:
tsk->min_flt++;
break;
case 2:
tsk->maj_flt++;
break;
case 0:
goto do_sigbus;
default:
goto out_of_memory;
}
up_read(&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_read(&mm->mmap_sem);
/* User mode accesses just cause a SIGSEGV */
if (psw_mask & PSW_PROBLEM_STATE) {
struct siginfo si;
tsk->thread.prot_addr = address;
tsk->thread.trap_no = error_code;
#ifndef CONFIG_SYSCTL
#ifdef CONFIG_PROCESS_DEBUG
printk("User process fault: interruption code 0x%lX\n",error_code);
printk("failing address: %lX\n",address);
show_regs(regs);
#endif
#else
if (sysctl_userprocess_debug) {
printk("User process fault: interruption code 0x%lX\n",
error_code);
printk("failing address: %lX\n", address);
show_regs(regs);
}
#endif
si.si_signo = SIGSEGV;
si.si_code = si_code;
si.si_addr = (void*) address;
force_sig_info(SIGSEGV, &si, tsk);
return;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if ((fixup = search_exception_table(regs->psw.addr)) != 0) {
regs->psw.addr = fixup;
return;
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
if (kernel_address)
printk(KERN_ALERT "Unable to handle kernel pointer dereference"
" at virtual kernel address %016lx\n", address);
else
printk(KERN_ALERT "Unable to handle kernel paging request"
" at virtual user address %016lx\n", address);
/*
* need to define, which information is useful here
*/
die("Oops", regs, error_code);
do_exit(SIGKILL);
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
up_read(&mm->mmap_sem);
printk("VM: killing process %s\n", tsk->comm);
if (psw_mask & PSW_PROBLEM_STATE)
do_exit(SIGKILL);
goto no_context;
do_sigbus:
up_read(&mm->mmap_sem);
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
tsk->thread.prot_addr = address;
tsk->thread.trap_no = error_code;
force_sig(SIGBUS, tsk);
/* Kernel mode? Handle exceptions or die */
if (!(psw_mask & PSW_PROBLEM_STATE))
goto no_context;
}
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