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[PATCH] i386: adjustments to page table dump during oops (v4)

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- make the page table contents printing PAE capable
- make sure the address stored in current->thread.cr2 is unmodified
  from what was read from CR2
- don't call oops_may_print() multiple times, when one time suffices
- print pte even in highpte case, as long as the pte page isn't in
  actually in high memory (which is specifically the case for all page
  tables covering kernel space)

(Changes to v3: Use sizeof()*2 rather than the suggested sizeof()*4 for
printing width, use fixed 16-nibble width for PAE, and also apply the
max_low_pfn range check to the middle level lookup on PAE.)

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
This commit is contained in:
Jan Beulich 2007-05-02 19:27:04 +02:00 committed by Andi Kleen
parent 3c43f03908
commit 28609f6e49
1 changed files with 35 additions and 20 deletions
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55
arch/i386/mm/fault.c
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@ -20,6 +20,7 @@
#include <linux/tty.h>
#include <linux/vt_kern.h> /* For unblank_screen() */
#include <linux/highmem.h>
#include <linux/bootmem.h> /* for max_low_pfn */
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
@ -301,7 +302,6 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
struct mm_struct *mm;
struct vm_area_struct * vma;
unsigned long address;
unsigned long page;
int write, si_code;
/* get the address */
@ -510,7 +510,9 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
bust_spinlocks(1);
if (oops_may_print()) {
#ifdef CONFIG_X86_PAE
__typeof__(pte_val(__pte(0))) page;
#ifdef CONFIG_X86_PAE
if (error_code & 16) {
pte_t *pte = lookup_address(address);
@ -519,7 +521,7 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
"NX-protected page - exploit attempt? "
"(uid: %d)\n", current->uid);
}
#endif
#endif
if (address < PAGE_SIZE)
printk(KERN_ALERT "BUG: unable to handle kernel NULL "
"pointer dereference");
@ -529,25 +531,38 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
printk(" at virtual address %08lx\n",address);
printk(KERN_ALERT " printing eip:\n");
printk("%08lx\n", regs->eip);
}
page = read_cr3();
page = ((unsigned long *) __va(page))[address >> 22];
if (oops_may_print())
page = read_cr3();
page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT];
#ifdef CONFIG_X86_PAE
printk(KERN_ALERT "*pdpt = %016Lx\n", page);
if ((page >> PAGE_SHIFT) < max_low_pfn
&& page & _PAGE_PRESENT) {
page &= PAGE_MASK;
page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT)
& (PTRS_PER_PMD - 1)];
printk(KERN_ALERT "*pde = %016Lx\n", page);
page &= ~_PAGE_NX;
}
#else
printk(KERN_ALERT "*pde = %08lx\n", page);
/*
* We must not directly access the pte in the highpte
* case, the page table might be allocated in highmem.
* And lets rather not kmap-atomic the pte, just in case
* it's allocated already.
*/
#ifndef CONFIG_HIGHPTE
if ((page & 1) && oops_may_print()) {
page &= PAGE_MASK;
address &= 0x003ff000;
page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
printk(KERN_ALERT "*pte = %08lx\n", page);
}
#endif
/*
* We must not directly access the pte in the highpte
* case if the page table is located in highmem.
* And let's rather not kmap-atomic the pte, just in case
* it's allocated already.
*/
if ((page >> PAGE_SHIFT) < max_low_pfn
&& (page & _PAGE_PRESENT)) {
page &= PAGE_MASK;
page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT)
& (PTRS_PER_PTE - 1)];
printk(KERN_ALERT "*pte = %0*Lx\n", sizeof(page)*2, (u64)page);
}
}
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
tsk->thread.error_code = error_code;