Commit 28609f6e authored by Jan Beulich's avatar Jan Beulich Committed by Andi Kleen
Browse files

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



- 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: default avatarJan Beulich <jbeulich@novell.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent 3c43f039

arch/i386/mm/fault.c

+35 −20
Original line number Diff line number Diff line
@@ -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 */
@@ -510,6 +510,8 @@ no_context: 
	bust_spinlocks(1);



	if (oops_may_print()) {

		__typeof__(pte_val(__pte(0))) page;



#ifdef CONFIG_X86_PAE

		if (error_code & 16) {

			pte_t *pte = lookup_address(address);
@@ -529,25 +531,38 @@ no_context: 
		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 = ((__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);

#endif



		/*

		 * 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

		 * 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.

		 */

#ifndef CONFIG_HIGHPTE

	if ((page & 1) && oops_may_print()) {

		if ((page >> PAGE_SHIFT) < max_low_pfn

		    && (page & _PAGE_PRESENT)) {

			page &= PAGE_MASK;

		address &= 0x003ff000;

		page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];

		printk(KERN_ALERT "*pte = %08lx\n", page);

			page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT)

			                                         & (PTRS_PER_PTE - 1)];

			printk(KERN_ALERT "*pte = %0*Lx\n", sizeof(page)*2, (u64)page);

		}

#endif

	}



	tsk->thread.cr2 = address;

	tsk->thread.trap_no = 14;

	tsk->thread.error_code = error_code;

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