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x86_32: remove __PAGE_KERNEL(_EXEC)

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From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Older x86-32 processors do not support global mappings (PGD), so must
only use it if the processor supports it.

The _PAGE_KERNEL* flags always have _PAGE_KERNEL set, since logically
we always want it set.

This is OK even on processors which do not support PGD, since all
_PAGE flags are masked with __supported_pte_mask before being turned
into a real in-pagetable pte.  On 32-bit systems, __supported_pte_mask
is initialized to not contain _PAGE_GLOBAL, and it is then added if
the CPU is found to support it.

The x86-32 code used to use __PAGE_KERNEL/__PAGE_KERNEL_EXEC for this
purpose, but they're now redundant and can be removed.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jeremy Fitzhardinge 2008-07-01 16:46:36 -07:00 committed by Ingo Molnar
parent 8490638cf0
commit ef5e94af16
2 changed files with 2 additions and 18 deletions
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10
arch/x86/mm/init_32.c
View file

@ -383,11 +383,6 @@ static void __init set_highmem_pages_init(void)
# define set_highmem_pages_init() do { } while (0)
#endif /* CONFIG_HIGHMEM */
pteval_t __PAGE_KERNEL = _PAGE_KERNEL;
EXPORT_SYMBOL(__PAGE_KERNEL);
pteval_t __PAGE_KERNEL_EXEC = _PAGE_KERNEL_EXEC;
void __init native_pagetable_setup_start(pgd_t *base)
{
unsigned long pfn, va;
@ -509,7 +504,7 @@ void zap_low_mappings(void)
int nx_enabled;
pteval_t __supported_pte_mask __read_mostly = ~_PAGE_NX;
pteval_t __supported_pte_mask __read_mostly = ~(_PAGE_NX | _PAGE_GLOBAL);
EXPORT_SYMBOL_GPL(__supported_pte_mask);
#ifdef CONFIG_X86_PAE
@ -796,8 +791,7 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
/* Enable PGE if available */
if (cpu_has_pge) {
set_in_cr4(X86_CR4_PGE);
__PAGE_KERNEL |= _PAGE_GLOBAL;
__PAGE_KERNEL_EXEC |= _PAGE_GLOBAL;
__supported_pte_mask |= _PAGE_GLOBAL;
}
/*

10
include/asm-x86/pgtable.h
View file

@ -78,19 +78,9 @@
#define PAGE_READONLY_EXEC __pgprot(_PAGE_PRESENT | _PAGE_USER | \
_PAGE_ACCESSED)
#ifdef CONFIG_X86_32
#define _PAGE_KERNEL_EXEC \
(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED)
#define _PAGE_KERNEL (_PAGE_KERNEL_EXEC | _PAGE_NX)
#ifndef __ASSEMBLY__
extern pteval_t __PAGE_KERNEL, __PAGE_KERNEL_EXEC;
#endif /* __ASSEMBLY__ */
#else
#define __PAGE_KERNEL_EXEC \
(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_GLOBAL)
#define __PAGE_KERNEL (__PAGE_KERNEL_EXEC | _PAGE_NX)
#endif
#define __PAGE_KERNEL_RO (__PAGE_KERNEL & ~_PAGE_RW)
#define __PAGE_KERNEL_RX (__PAGE_KERNEL_EXEC & ~_PAGE_RW)