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Commit 2326df55 authored by Yang Shi's avatar Yang Shi Committed by Will Deacon
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arm64: always use STRICT_MM_TYPECHECKS 

Inspired by the counterpart of powerpc [1], which shows there is no negative
effect on code generation from enabling STRICT_MM_TYPECHECKS with a modern
compiler.

And, Arnd's comment [2] about that patch says STRICT_MM_TYPECHECKS could
be default as long as the architecture can pass structures in registers as
function arguments. ARM64 can do it as long as the size of structure <= 16
bytes. All the page table value types are u64 on ARM64.

The below disassembly demonstrates it, entry is pte_t type:

            entry = arch_make_huge_pte(entry, vma, page, writable);
   0xffff00000826fc38 <+80>:    and     x0, x0, #0xfffffffffffffffd
   0xffff00000826fc3c <+84>:    mov     w3, w21
   0xffff00000826fc40 <+88>:    mov     x2, x20
   0xffff00000826fc44 <+92>:    mov     x1, x19
   0xffff00000826fc48 <+96>:    orr     x0, x0, #0x400
   0xffff00000826fc4c <+100>:   bl      0xffff00000809bcc0 <arch_make_huge_pte>

[1] http://www.spinics.net/lists/linux-mm/msg105951.html
[2] http://www.spinics.net/lists/linux-mm/msg105969.html



Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarYang Shi <yang.shi@linaro.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent c612505f

arch/arm64/include/asm/pgtable-types.h

+0 −32
Original line number Diff line number Diff line
@@ -27,10 +27,6 @@ typedef u64 pmdval_t; 
typedef u64 pudval_t;

typedef u64 pgdval_t;



#undef STRICT_MM_TYPECHECKS



#ifdef STRICT_MM_TYPECHECKS



/*

 * These are used to make use of C type-checking..

 */
@@ -58,34 +54,6 @@ typedef struct { pteval_t pgprot; } pgprot_t; 
#define pgprot_val(x)	((x).pgprot)

#define __pgprot(x)	((pgprot_t) { (x) } )



#else	/* !STRICT_MM_TYPECHECKS */



typedef pteval_t pte_t;

#define pte_val(x)	(x)

#define __pte(x)	(x)



#if CONFIG_PGTABLE_LEVELS > 2

typedef pmdval_t pmd_t;

#define pmd_val(x)	(x)

#define __pmd(x)	(x)

#endif



#if CONFIG_PGTABLE_LEVELS > 3

typedef pudval_t pud_t;

#define pud_val(x)	(x)

#define __pud(x)	(x)

#endif



typedef pgdval_t pgd_t;

#define pgd_val(x)	(x)

#define __pgd(x)	(x)



typedef pteval_t pgprot_t;

#define pgprot_val(x)	(x)

#define __pgprot(x)	(x)



#endif /* STRICT_MM_TYPECHECKS */



#if CONFIG_PGTABLE_LEVELS == 2

#include <asm-generic/pgtable-nopmd.h>

#elif CONFIG_PGTABLE_LEVELS == 3