/*
* Copyright (C) 2004-2006 Atmel Corporation
*
* Based on linux/arch/sh/mm/fault.c:
* Copyright (C) 1999 Niibe Yutaka
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <asm/kdebug.h>
#include <asm/mmu_context.h>
#include <asm/sysreg.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#ifdef DEBUG
static void dump_code(unsigned long pc)
{
char *p = (char *)pc;
char val;
int i;
printk(KERN_DEBUG "Code:");
for (i = 0; i < 16; i++) {
if (__get_user(val, p + i))
break;
printk(" %02x", val);
}
printk("\n");
}
#endif
#ifdef CONFIG_KPROBES
ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
/* Hook to register for page fault notifications */
int register_page_fault_notifier(struct notifier_block *nb)
{
return atomic_notifier_chain_register(¬ify_page_fault_chain, nb);
}
int unregister_page_fault_notifier(struct notifier_block *nb)
{
return atomic_notifier_chain_unregister(¬ify_page_fault_chain, nb);
}
static inline int notify_page_fault(enum die_val val, struct pt_regs *regs,
int trap, int sig)
{
struct die_args args = {
.regs = regs,
.trapnr = trap,
};
return atomic_notifier_call_chain(¬ify_page_fault_chain, val, &args);
}
#else
static inline int notify_page_fault(enum die_val val, struct pt_regs *regs,
int trap, int sig)
{
return NOTIFY_DONE;
}
#endif
/*
* This routine handles page faults. It determines the address and the
* problem, and then passes it off to one of the appropriate routines.
*
* ecr is the Exception Cause Register. Possible values are:
* 5: Page not found (instruction access)
* 6: Protection fault (instruction access)
* 12: Page not found (read access)
* 13: Page not found (write access)
* 14: Protection fault (read access)
* 15: Protection fault (write access)
*/
asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct *vma;
const struct exception_table_entry *fixup;
unsigned long address;
unsigned long page;
int writeaccess = 0;
if (notify_page_fault(DIE_PAGE_FAULT, regs,
ecr, SIGSEGV) == NOTIFY_STOP)
return;
address = sysreg_read(TLBEAR);
tsk = current;
mm = tsk->mm;
/*
* If we're in an interrupt or have no user context, we must
* not take the fault...
*/
if (in_atomic() || !mm || regs->sr & SYSREG_BIT(GM))
goto no_context;
local_irq_enable();
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 (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:
//pr_debug("good area: vm_flags = 0x%lx\n", vma->vm_flags);
switch (ecr) {
case ECR_PROTECTION_X:
case ECR_TLB_MISS_X:
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
break;
case ECR_PROTECTION_R:
case ECR_TLB_MISS_R:
if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
goto bad_area;
break;
case ECR_PROTECTION_W:
case ECR_TLB_MISS_W:
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
writeaccess = 1;
break;
default:
panic("Unhandled case %lu in do_page_fault!", ecr);
}
/*
* If for any reason at all we couldn't handle the fault, make
* sure we exit gracefully rather than endlessly redo the
* fault.
*/
survive:
switch (handle_mm_fault(mm, vma, address, writeaccess)) {
case VM_FAULT_MINOR:
tsk->min_flt++;
break;
case VM_FAULT_MAJOR:
tsk->maj_flt++;
break;
case VM_FAULT_SIGBUS:
goto do_sigbus;
case VM_FAULT_OOM:
goto out_of_memory;
default:
BUG();
}
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:
pr_debug("Bad area [%s:%u]: addr %08lx, ecr %lu\n",
tsk->comm, tsk->pid, address, ecr);
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
/* Hmm...we have to pass address and ecr somehow... */
/* tsk->thread.address = address;
tsk->thread.error_code = ecr; */
#ifdef DEBUG
show_regs(regs);
dump_code(regs->pc);
page = sysreg_read(PTBR);
printk("ptbr = %08lx", page);
if (page) {
page = ((unsigned long *)page)[address >> 22];
printk(" pgd = %08lx", page);
if (page & _PAGE_PRESENT) {
page &= PAGE_MASK;
address &= 0x003ff000;
page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
printk(" pte = %08lx\n", page);
}
}
#endif
pr_debug("Sending SIGSEGV to PID %d...\n",
tsk->pid);
force_sig(SIGSEGV, tsk);
return;
}
no_context:
pr_debug("No context\n");
/* Are we prepared to handle this kernel fault? */
fixup = search_exception_tables(regs->pc);
if (fixup) {
regs->pc = fixup->fixup;
pr_debug("Found fixup at %08lx\n", fixup->fixup);
return;
}
/*
* Oops. The kernel tried to access some bad page. We'll have
* to terminate things with extreme prejudice.
*/
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(KERN_ALERT "pc = %08lx\n", regs->pc);
page = sysreg_read(PTBR);
printk(KERN_ALERT "ptbr = %08lx", page);
if (page) {
page = ((unsigned long *)page)[address >> 22];
printk(" pgd = %08lx", page);
if (page & _PAGE_PRESENT) {
page &= PAGE_MASK;
address &= 0x003ff000;
page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
printk(" pte = %08lx\n", page);
}
}
die("\nOops", regs, ecr);
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:
printk("Out of memory\n");
up_read(&mm->mmap_sem);
if (current->pid == 1) {
yield();
down_read(&mm->mmap_sem);
goto survive;
}
printk("VM: Killing process %s\n", tsk->comm);
if (user_mode(regs))
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.
*/
/* address, error_code, trap_no, ... */
#ifdef DEBUG
show_regs(regs);
dump_code(regs->pc);
#endif
pr_debug("Sending SIGBUS to PID %d...\n", tsk->pid);
force_sig(SIGBUS, tsk);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
goto no_context;
}
asmlinkage void do_bus_error(unsigned long addr, int write_access,
struct pt_regs *regs)
{
printk(KERN_ALERT
"Bus error at physical address 0x%08lx (%s access)\n",
addr, write_access ? "write" : "read");
printk(KERN_INFO "DTLB dump:\n");
dump_dtlb();
die("Bus Error", regs, write_access);
do_exit(SIGKILL);
}
/*
* This functionality is currently not possible to implement because
* we're using segmentation to ensure a fixed mapping of the kernel
* virtual address space.
*
* It would be possible to implement this, but it would require us to
* disable segmentation at startup and load the kernel mappings into
* the TLB like any other pages. There will be lots of trickery to
* avoid recursive invocation of the TLB miss handler, though...
*/
#ifdef CONFIG_DEBUG_PAGEALLOC
void kernel_map_pages(struct page *page, int numpages, int enable)
{
}
EXPORT_SYMBOL(kernel_map_pages);
#endif
