/* $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 <linux/module.h>
#include <asm/uaccess.h>
#include <asm/traps.h>
#define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */
/* dumped to the console via printk) */
/* 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 */
DEFINE_PER_CPU(struct exception_data, exception_data);
/*
* 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
#if 0
/* This is the treewalk to find a vma which is the highest that has
* a start < addr. We're using find_vma_prev instead right now, but
* we might want to use this at some point in the future. Probably
* not, but I want it committed to CVS so I don't lose it :-)
*/
while (tree != vm_avl_empty) {
if (tree->vm_start > addr) {
tree = tree->vm_avl_left;
} else {
prev = tree;
if (prev->vm_next == NULL)
break;
if (prev->vm_next->vm_start > addr)
break;
tree = tree->vm_avl_right;
}
}
#endif
void do_page_fault(struct pt_regs *regs, unsigned long code,
unsigned long address)
{
struct vm_area_struct *vma, *prev_vma;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
const struct exception_table_entry *fix;
unsigned long acc_type;
int fault;
if (in_atomic() || !mm)
goto no_context;
down_read(&mm->mmap_sem);
vma = find_vma_prev(mm, address, &prev_vma);
if (!vma || address < vma->vm_start)
goto check_expansion;
/*
* 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.
*/
fault = handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) != 0);
if (unlikely(fault & VM_FAULT_ERROR)) {
/*
* We hit a shared mapping outside of the file, or some
* other thing happened to us that made us unable to
* handle the page fault gracefully.
*/
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto bad_area;
BUG();
}
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
up_read(&mm->mmap_sem);
return;
check_expansion:
vma = prev_vma;
if (vma && (expand_stack(vma, address) == 0))
goto good_area;
/*
* 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;
#ifdef PRINT_USER_FAULTS
printk(KERN_DEBUG "\n");
printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n",
task_pid_nr(tsk), tsk->comm, code, address);
if (vma) {
printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n",
vma->vm_start, vma->vm_end);
}
show_regs(regs);
#endif
/* 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 __user *) address;
force_sig_info(SIGSEGV, &si, current);
return;
}
no_context:
if (!user_mode(regs)) {
fix = search_exception_tables(regs->iaoq[0]);
if (fix) {
struct exception_data *d;
d = &__get_cpu_var(exception_data);
d->fault_ip = regs->iaoq[0];
d->fault_space = regs->isr;
d->fault_addr = regs->ior;
regs->iaoq[0] = ((fix->fixup) & ~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(KERN_CRIT "VM: killing process %s\n", current->comm);
if (user_mode(regs))
do_group_exit(SIGKILL);
goto no_context;
}
