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
......@@ -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);
......@@ -417,17 +417,17 @@ 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 */
case 0: /* read, not present */
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
......@@ -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;
......
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