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Commit 66c58156 authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
Browse files

[PATCH] x86_64: Convert page fault error codes to symbolic constants. 



Much better to deal with these than with the magic numbers.

And remove the comment describing the bits - kernel source
is no replacement for an architecture manual.

Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent bf2fcc6f

arch/x86_64/mm/fault.c

+17 −17
Original line number Diff line number Diff line
@@ -35,6 +35,13 @@ 
#include <asm-generic/sections.h>

#include <asm/kdebug.h>



/* Page fault error code bits */

#define PF_PROT	(1<<0)		/* or no page found */

#define PF_WRITE	(1<<1)

#define PF_USER	(1<<2)

#define PF_RSVD	(1<<3)

#define PF_INSTR	(1<<4)



void bust_spinlocks(int yes)

{

	int loglevel_save = console_loglevel;
@@ -68,7 +75,7 @@ static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr, 
	unsigned char *max_instr;



	/* If it was a exec fault ignore */

	if (error_code & (1<<4))

	if (error_code & PF_INSTR)

		return 0;

	

	instr = (unsigned char *)convert_rip_to_linear(current, regs);
@@ -293,13 +300,6 @@ int exception_trace = 1; 
 * This routine handles page faults.  It determines the address,

 * and the problem, and then passes it off to one of the appropriate

 * routines.

 *

 * error_code:

 *	bit 0 == 0 means no page found, 1 means protection fault

 *	bit 1 == 0 means read, 1 means write

 *	bit 2 == 0 means kernel, 1 means user-mode

 *	bit 3 == 1 means use of reserved bit detected

 *	bit 4 == 1 means fault was an instruction fetch

 */

asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,

					unsigned long error_code)
@@ -350,7 +350,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
		 * is always initialized because it's shared with the main

		 * kernel text. Only vmalloc may need PML4 syncups.

		 */

		if (!(error_code & 0xd) &&

		if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) &&

		      ((address >= VMALLOC_START && address < VMALLOC_END))) {

			if (vmalloc_fault(address) < 0)

				goto bad_area_nosemaphore;
@@ -363,7 +363,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
		goto bad_area_nosemaphore;

	}



	if (unlikely(error_code & (1 << 3)))

	if (unlikely(error_code & PF_RSVD))

		pgtable_bad(address, regs, error_code);



	/*
@@ -390,7 +390,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
	 * thus avoiding the deadlock.

	 */

	if (!down_read_trylock(&mm->mmap_sem)) {

		if ((error_code & 4) == 0 &&

		if ((error_code & PF_USER) == 0 &&

		    !search_exception_tables(regs->rip))

			goto bad_area_nosemaphore;

		down_read(&mm->mmap_sem);
@@ -417,15 +417,15 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
good_area:

	info.si_code = SEGV_ACCERR;

	write = 0;

	switch (error_code & 3) {

	switch (error_code & (PF_PROT|PF_WRITE)) {

		default:	/* 3: write, present */

			/* fall through */

		case 2:		/* write, not present */

		case PF_WRITE:		/* write, not present */

			if (!(vma->vm_flags & VM_WRITE))

				goto bad_area;

			write++;

			break;

		case 1:		/* read, present */

		case PF_PROT:		/* read, present */

			goto bad_area;

		case 0:			/* read, not present */

			if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
@@ -462,7 +462,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 


bad_area_nosemaphore:

	/* User mode accesses just cause a SIGSEGV */

	if (error_code & 4) {

	if (error_code & PF_USER) {

		if (is_prefetch(regs, address, error_code))

			return;
@@ -558,7 +558,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, 
	up_read(&mm->mmap_sem);



	/* Kernel mode? Handle exceptions or die */

	if (!(error_code & 4))

	if (!(error_code & PF_USER))

		goto no_context;



	tsk->thread.cr2 = address;