/* MN10300 MMU Fault handler
*
* Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Modified by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#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/interrupt.h>
#include <linux/init.h>
#include <linux/vt_kern.h> /* For unblank_screen() */
#include <linux/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/hardirq.h>
#include <asm/cpu-regs.h>
#include <asm/debugger.h>
#include <asm/gdb-stub.h>
/*
* Unlock any spinlocks which will prevent us from getting the
* message out
*/
void bust_spinlocks(int yes)
{
if (yes) {
oops_in_progress = 1;
} else {
int loglevel_save = console_loglevel;
#ifdef CONFIG_VT
unblank_screen();
#endif
oops_in_progress = 0;
/*
* OK, the message is on the console. Now we call printk()
* without oops_in_progress set so that printk will give klogd
* a poke. Hold onto your hats...
*/
console_loglevel = 15; /* NMI oopser may have shut the console
* up */
printk(" ");
console_loglevel = loglevel_save;
}
}
void do_BUG(const char *file, int line)
{
bust_spinlocks(1);
printk(KERN_EMERG "------------[ cut here ]------------\n");
printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
}
#if 0
static void print_pagetable_entries(pgd_t *pgdir, unsigned long address)
{
pgd_t *pgd;
pmd_t *pmd;
pte_t *pte;
pgd = pgdir + __pgd_offset(address);
printk(KERN_DEBUG "pgd entry %p: %016Lx\n",
pgd, (long long) pgd_val(*pgd));
if (!pgd_present(*pgd)) {
printk(KERN_DEBUG "... pgd not present!\n");
return;
}
pmd = pmd_offset(pgd, address);
printk(KERN_DEBUG "pmd entry %p: %016Lx\n",
pmd, (long long)pmd_val(*pmd));
if (!pmd_present(*pmd)) {
printk(KERN_DEBUG "... pmd not present!\n");
return;
}
pte = pte_offset(pmd, address);
printk(KERN_DEBUG "pte entry %p: %016Lx\n",
pte, (long long) pte_val(*pte));
if (!pte_present(*pte))
printk(KERN_DEBUG "... pte not present!\n");
}
#endif
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*
* fault_code:
* - LSW: either MMUFCR_IFC or MMUFCR_DFC as appropriate
* - MSW: 0 if data access, 1 if instruction access
* - bit 0: TLB miss flag
* - bit 1: initial write
* - bit 2: page invalid
* - bit 3: protection violation
* - bit 4: accessor (0=user 1=kernel)
* - bit 5: 0=read 1=write
* - bit 6-8: page protection spec
* - bit 9: illegal address
* - bit 16: 0=data 1=ins
*
*/
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
unsigned long address)
{
struct vm_area_struct *vma;
struct task_struct *tsk;
struct mm_struct *mm;
unsigned long page;
siginfo_t info;
int fault;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
#ifdef CONFIG_GDBSTUB
/* handle GDB stub causing a fault */
if (gdbstub_busy) {
gdbstub_exception(regs, TBR & TBR_INT_CODE);
return;
}
#endif
#if 0
printk(KERN_DEBUG "--- do_page_fault(%p,%s:%04lx,%08lx)\n",
regs,
fault_code & 0x10000 ? "ins" : "data",
fault_code & 0xffff, address);
#endif
tsk = current;
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*
* This verifies that the fault happens in kernel space
* and that the fault was a page not present (invalid) error
*/
if (address >= VMALLOC_START && address < VMALLOC_END &&
(fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR &&
(fault_code & MMUFCR_xFC_PGINVAL) == MMUFCR_xFC_PGINVAL
)
goto vmalloc_fault;
mm = tsk->mm;
info.si_code = SEGV_MAPERR;
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (faulthandler_disabled() || !mm)
goto no_context;
if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
flags |= FAULT_FLAG_USER;
retry:
down_read(&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 ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
/* accessing the stack below the stack pointer is always a
* bug */
if ((address & PAGE_MASK) + 2 * PAGE_SIZE < regs->sp) {
#if 0
printk(KERN_WARNING
"[%d] ### Access below stack @%lx (sp=%lx)\n",
current->pid, address, regs->sp);
printk(KERN_WARNING
"vma [%08x - %08x]\n",
vma->vm_start, vma->vm_end);
show_registers(regs);
printk(KERN_WARNING
"[%d] ### Code: [%08lx]"
" %02x %02x %02x %02x %02x %02x %02x %02x\n",
current->pid,
regs->pc,
((u8 *) regs->pc)[0],
((u8 *) regs->pc)[1],
((u8 *) regs->pc)[2],
((u8 *) regs->pc)[3],
((u8 *) regs->pc)[4],
((u8 *) regs->pc)[5],
((u8 *) regs->pc)[6],
((u8 *) regs->pc)[7]
);
#endif
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:
info.si_code = SEGV_ACCERR;
switch (fault_code & (MMUFCR_xFC_PGINVAL|MMUFCR_xFC_TYPE)) {
default: /* 3: write, present */
case MMUFCR_xFC_TYPE_WRITE:
#ifdef TEST_VERIFY_AREA
if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
printk(KERN_DEBUG "WP fault at %08lx\n", regs->pc);
#endif
/* write to absent page */
case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_WRITE:
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
break;
/* read from protected page */
case MMUFCR_xFC_TYPE_READ:
goto bad_area;
/* read from absent page present */
case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_READ:
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
break;
}
/*
* 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, flags);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGSEGV)
goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
/* No need to up_read(&mm->mmap_sem) as we would
* have already released it in __lock_page_or_retry
* in mm/filemap.c.
*/
goto retry;
}
}
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 ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
info.si_signo = SIGSEGV;
info.si_errno = 0;
/* info.si_code has been set above */
info.si_addr = (void *)address;
force_sig_info(SIGSEGV, &info, tsk);
return;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if (fixup_exception(regs))
return;
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
bust_spinlocks(1);
if (address < PAGE_SIZE)
printk(KERN_ALERT
"Unable to handle kernel NULL pointer dereference");
else
printk(KERN_ALERT
"Unable to handle kernel paging request");
printk(" at virtual address %08lx\n", address);
printk(" printing pc:\n");
printk(KERN_ALERT "%08lx\n", regs->pc);
debugger_intercept(fault_code & 0x00010000 ? EXCEP_IAERROR : EXCEP_DAERROR,
SIGSEGV, SEGV_ACCERR, regs);
page = PTBR;
page = ((unsigned long *) __va(page))[address >> 22];
printk(KERN_ALERT "*pde = %08lx\n", page);
if (page & 1) {
page &= PAGE_MASK;
address &= 0x003ff000;
page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
printk(KERN_ALERT "*pte = %08lx\n", page);
}
die("Oops", regs, fault_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);
if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
pagefault_out_of_memory();
return;
}
goto no_context;
do_sigbus:
up_read(&mm->mmap_sem);
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
info.si_addr = (void *)address;
force_sig_info(SIGBUS, &info, tsk);
/* Kernel mode? Handle exceptions or die */
if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
goto no_context;
return;
vmalloc_fault:
{
/*
* Synchronize this task's top level page-table
* with the 'reference' page table.
*
* Do _not_ use "tsk" here. We might be inside
* an interrupt in the middle of a task switch..
*/
int index = pgd_index(address);
pgd_t *pgd, *pgd_k;
pud_t *pud, *pud_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
pgd_k = init_mm.pgd + index;
if (!pgd_present(*pgd_k))
goto no_context;
pud_k = pud_offset(pgd_k, address);
if (!pud_present(*pud_k))
goto no_context;
pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
goto no_context;
pgd = (pgd_t *) PTBR + index;
pud = pud_offset(pgd, address);
pmd = pmd_offset(pud, address);
set_pmd(pmd, *pmd_k);
pte_k = pte_offset_kernel(pmd_k, address);
if (!pte_present(*pte_k))
goto no_context;
return;
}
}
