For PAE kernels "unsigned long" is not suitable to hold page protection
flags, since _PAGE_NX doesn't fit there. This is the reason for quite a
few W+X pages getting reported as insecure during boot (observed namely
for the entire initrd range).
Quite the other way around, "unsigned long" is inefficient for 64-bit
kernels when dealing with cachability flags alone - "unsigned int" is
sufficient here and allows for slightly smaller code to be generated.
Fixes: 281d4078be ("x86: Make page cache mode a real type")
Signed-off-by: Jan Beulich <[email protected]>
Cc: Juergen Gross <[email protected]>
---
arch/x86/include/asm/pgtable_types.h | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
--- 4.5-rc1/arch/x86/include/asm/pgtable_types.h
+++ 4.5-rc1-ix86-PAE-pgprot-xlat/arch/x86/include/asm/pgtable_types.h
@@ -357,9 +357,8 @@ static inline pgprot_t cachemode2pgprot(
}
static inline enum page_cache_mode pgprot2cachemode(pgprot_t pgprot)
{
- unsigned long masked;
+ unsigned int masked = pgprot_val(pgprot) & _PAGE_CACHE_MASK;
- masked = pgprot_val(pgprot) & _PAGE_CACHE_MASK;
if (likely(masked == 0))
return 0;
return __pte2cachemode_tbl[__pte2cm_idx(masked)];
@@ -367,9 +366,8 @@ static inline enum page_cache_mode pgpro
static inline pgprot_t pgprot_4k_2_large(pgprot_t pgprot)
{
pgprot_t new;
- unsigned long val;
+ pgprotval_t val = pgprot_val(pgprot);
- val = pgprot_val(pgprot);
pgprot_val(new) = (val & ~(_PAGE_PAT | _PAGE_PAT_LARGE)) |
((val & _PAGE_PAT) << (_PAGE_BIT_PAT_LARGE - _PAGE_BIT_PAT));
return new;
@@ -377,9 +375,8 @@ static inline pgprot_t pgprot_4k_2_large
static inline pgprot_t pgprot_large_2_4k(pgprot_t pgprot)
{
pgprot_t new;
- unsigned long val;
+ pgprotval_t val = pgprot_val(pgprot);
- val = pgprot_val(pgprot);
pgprot_val(new) = (val & ~(_PAGE_PAT | _PAGE_PAT_LARGE)) |
((val & _PAGE_PAT_LARGE) >>
(_PAGE_BIT_PAT_LARGE - _PAGE_BIT_PAT));
