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/* $Id: fault.c,v 1.5 2000/01/26 16:20:29 jsm Exp $
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
*
* Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
* Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
* Copyright 1999 Hewlett Packard Co.
*
*/
#include <linux/mm.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
/* Defines for parisc_acctyp() */
#define READ 0
#define WRITE 1
/* Various important other fields */
#define bit22set(x) (x & 0x00000200)
#define bits23_25set(x) (x & 0x000001c0)
#define isGraphicsFlushRead(x) ((x & 0xfc003fdf) == 0x04001a80)
/* extended opcode is 0x6a */
#define BITSSET 0x1c0 /* for identifying LDCW */
/*
* parisc_acctyp(unsigned int inst) --
* Given a PA-RISC memory access instruction, determine if the
* the instruction would perform a memory read or memory write
* operation.
*
* This function assumes that the given instruction is a memory access
* instruction (i.e. you should really only call it if you know that
* the instruction has generated some sort of a memory access fault).
*
* Returns:
* VM_READ if read operation
* VM_WRITE if write operation
* VM_EXEC if execute operation
*/
static unsigned long
parisc_acctyp(unsigned long code, unsigned int inst)
{
if (code == 6 || code == 16)
return VM_EXEC;
switch (inst & 0xf0000000) {
case 0x40000000: /* load */
case 0x50000000: /* new load */
return VM_READ;
case 0x60000000: /* store */
case 0x70000000: /* new store */
return VM_WRITE;
case 0x20000000: /* coproc */
case 0x30000000: /* coproc2 */
if (bit22set(inst))
return VM_WRITE;
case 0x0: /* indexed/memory management */
if (bit22set(inst)) {
/*
* Check for the 'Graphics Flush Read' instruction.
* It resembles an FDC instruction, except for bits
* 20 and 21. Any combination other than zero will
* utilize the block mover functionality on some
* older PA-RISC platforms. The case where a block
* move is performed from VM to graphics IO space
* should be treated as a READ.
*
* The significance of bits 20,21 in the FDC
* instruction is:
*
* 00 Flush data cache (normal instruction behavior)
* 01 Graphics flush write (IO space -> VM)
* 10 Graphics flush read (VM -> IO space)
* 11 Graphics flush read/write (VM <-> IO space)
*/
if (isGraphicsFlushRead(inst))
return VM_READ;
return VM_WRITE;
} else {
/*
* Check for LDCWX and LDCWS (semaphore instructions).
* If bits 23 through 25 are all 1's it is one of
* the above two instructions and is a write.
*
* Note: With the limited bits we are looking at,
* this will also catch PROBEW and PROBEWI. However,
* these should never get in here because they don't
* generate exceptions of the type:
* Data TLB miss fault/data page fault
* Data memory protection trap
*/
if (bits23_25set(inst) == BITSSET)
return VM_WRITE;
}
return VM_READ; /* Default */
}
return VM_READ; /* Default */
}
#undef bit22set
#undef bits23_25set
#undef isGraphicsFlushRead
#undef BITSSET
/* This is similar to expand_stack(), except that it is for stacks
* that grow upwards.
*/
static inline int expand_stackup(struct vm_area_struct * vma, unsigned long address)
{
unsigned long grow;
address += 4 + PAGE_SIZE - 1;
address &= PAGE_MASK;
grow = (address - vma->vm_end) >> PAGE_SHIFT;
if (address - vma->vm_start > current->rlim[RLIMIT_STACK].rlim_cur ||
((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) > current->rlim[RLIMIT_AS].rlim_cur)
return -ENOMEM;
vma->vm_end = address;
vma->vm_mm->total_vm += grow;
if (vma->vm_flags & VM_LOCKED)
vma->vm_mm->locked_vm += grow;
return 0;
}
/* This is similar to find_vma(), except that it understands that stacks
* grow up rather than down.
* XXX Optimise by making use of cache and avl tree as per find_vma().
*/
struct vm_area_struct * pa_find_vma(struct mm_struct * mm, unsigned long addr)
{
struct vm_area_struct *vma = NULL;
if (mm) {
vma = mm->mmap;
if (!vma || addr < vma->vm_start)
return NULL;
while (vma->vm_next && addr >= vma->vm_next->vm_start)
vma = vma->vm_next;
}
return vma;
}
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*/
extern void parisc_terminate(char *, struct pt_regs *, int, unsigned long);
void do_page_fault(struct pt_regs *regs, unsigned long code,
unsigned long address)
{
struct vm_area_struct * vma;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
const struct exception_table_entry *fix;
unsigned long acc_type;
if (in_interrupt() || !mm)
goto no_context;
down_read(&mm->mmap_sem);
vma = pa_find_vma(mm, address);
if (!vma)
goto bad_area;
if (address < vma->vm_end)
goto good_area;
if (!(vma->vm_flags & VM_GROWSUP) || expand_stackup(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access. We still need to
* check the access permissions.
*/
good_area:
acc_type = parisc_acctyp(code,regs->iir);
if ((vma->vm_flags & acc_type) != acc_type)
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, (acc_type & VM_WRITE) != 0)) {
case 1:
++current->min_flt;
break;
case 2:
++current->maj_flt;
break;
case 0:
/*
* We ran out of memory, or some other thing happened
* to us that made us unable to handle the page fault
* gracefully.
*/
goto bad_area;
default:
goto out_of_memory;
}
up_read(&mm->mmap_sem);
return;
/*
* Something tried to access memory that isn't in our memory map..
*/
bad_area:
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
struct siginfo si;
printk("\ndo_page_fault() pid=%d command='%s'\n",
tsk->pid, tsk->comm);
show_regs(regs);
/* FIXME: actually we need to get the signo and code correct */
si.si_signo = SIGSEGV;
si.si_errno = 0;
si.si_code = SEGV_MAPERR;
si.si_addr = (void *) address;
force_sig_info(SIGSEGV, &si, current);
return;
}
no_context:
if (!user_mode(regs)) {
fix = search_exception_table(regs->iaoq[0]);
if (fix) {
if (fix->skip & 1)
regs->gr[8] = -EFAULT;
if (fix->skip & 2)
regs->gr[9] = 0;
regs->iaoq[0] += ((fix->skip) & ~3);
/*
* NOTE: In some cases the faulting instruction
* may be in the delay slot of a branch. We
* don't want to take the branch, so we don't
* increment iaoq[1], instead we set it to be
* iaoq[0]+4, and clear the B bit in the PSW
*/
regs->iaoq[1] = regs->iaoq[0] + 4;
regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
return;
}
}
parisc_terminate("Bad Address (null pointer deref?)",regs,code,address);
out_of_memory:
up_read(&mm->mmap_sem);
printk("VM: killing process %s\n", current->comm);
if (user_mode(regs))
do_exit(SIGKILL);
goto no_context;
}
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