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Commit ef48e8e3 authored by Paul Mundt's avatar Paul Mundt
Browse files

sh: Free up some and document PTEL flags. 



Drop _PAGE_SHARED/_PAGE_U0_SHARED and document Linux PTE encodings in
the PTEL value. Preserve the swap cache entry encoding semantics for
now, though it will need rework to free up _PAGE_WT from _PAGE_FILE.

Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent 801e0458

include/asm-sh/pgtable.h

+45 −31
Original line number Diff line number Diff line
@@ -54,8 +54,31 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; 
#define VMALLOC_START	(P3SEG+0x00100000)

#define VMALLOC_END	(FIXADDR_START-2*PAGE_SIZE)



/*

 * Linux PTEL encoding.

 *

 * Hardware and software bit definitions for the PTEL value:

 *

 * - Bits 0 and 7 are reserved on SH-3 (_PAGE_WT and _PAGE_SZ1 on SH-4).

 *

 * - Bit 1 is the SH-bit, but is unused on SH-3 due to an MMU bug (the

 *   hardware PTEL value can't have the SH-bit set when MMUCR.IX is set,

 *   which is the default in cpu-sh3/mmu_context.h:MMU_CONTROL_INIT).

 *

 *   In order to keep this relatively clean, do not use these for defining

 *   SH-3 specific flags until all of the other unused bits have been

 *   exhausted.

 *

 * - Bit 9 is reserved by everyone and used by _PAGE_PROTNONE.

 *

 * - Bits 10 and 11 are low bits of the PPN that are reserved on >= 4K pages.

 *   Bit 10 is used for _PAGE_ACCESSED, bit 11 remains unused.

 *

 * - Bits 31, 30, and 29 remain unused by everyone and can be used for future

 *   software flags, although care must be taken to update _PAGE_CLEAR_FLAGS.

 */

#define	_PAGE_WT	0x001		/* WT-bit on SH-4, 0 on SH-3 */

#define _PAGE_HW_SHARED	0x002  /* SH-bit  : page is shared among processes */

#define _PAGE_HW_SHARED	0x002		/* SH-bit  : shared among processes */

#define _PAGE_DIRTY	0x004		/* D-bit   : page changed */

#define _PAGE_CACHABLE	0x008		/* C-bit   : cachable */

#define _PAGE_SZ0	0x010		/* SZ0-bit : Size of page */
@@ -65,8 +88,6 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; 
#define _PAGE_PRESENT	0x100		/* V-bit   : page is valid */

#define _PAGE_PROTNONE	0x200		/* software: if not present  */

#define _PAGE_ACCESSED	0x400		/* software: page referenced */

#define _PAGE_U0_SHARED 0x800  /* software: page is shared in user space */



#define _PAGE_FILE	_PAGE_WT	/* software: pagecache or swap? */



/* software: moves to PTEA.TC (Timing Control) */
@@ -82,22 +103,17 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; 
#define _PAGE_PCC_ATR8	0x60000000	/* Attribute Memory space, 8 bit bus */

#define _PAGE_PCC_ATR16	0x60000001	/* Attribute Memory space, 6 bit bus */



/* Mask which drop software flags

 * We also drop WT bit since it is used for _PAGE_FILE

 * bit in this implementation.

 */

#define _PAGE_CLEAR_FLAGS	(_PAGE_WT | _PAGE_PROTNONE | _PAGE_ACCESSED | _PAGE_U0_SHARED)



#if defined(CONFIG_CPU_SH3)

/*

 * MMU on SH-3 has bug on SH-bit: We can't use it if MMUCR.IX=1.

 * Work around: Just drop SH-bit.

 */

#define _PAGE_FLAGS_HARDWARE_MASK	(0x1fffffff & ~(_PAGE_CLEAR_FLAGS | _PAGE_HW_SHARED))

/* Mask which drops unused bits from the PTEL value */

#ifdef CONFIG_CPU_SH3

#define _PAGE_CLEAR_FLAGS	(_PAGE_PROTNONE | _PAGE_ACCESSED| \

				 _PAGE_FILE	| _PAGE_SZ1	| \

				 _PAGE_HW_SHARED)

#else

#define _PAGE_FLAGS_HARDWARE_MASK	(0x1fffffff & ~(_PAGE_CLEAR_FLAGS))

#define _PAGE_CLEAR_FLAGS	(_PAGE_PROTNONE | _PAGE_ACCESSED | _PAGE_FILE)

#endif



#define _PAGE_FLAGS_HARDWARE_MASK	(0x1fffffff & ~(_PAGE_CLEAR_FLAGS))



/* Hardware flags: SZ0=1 (4k-byte) */

#define _PAGE_FLAGS_HARD	_PAGE_SZ0
@@ -107,17 +123,15 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; 
#define _PAGE_SZHUGE	(_PAGE_SZ0 | _PAGE_SZ1)

#endif



#define _PAGE_SHARED	_PAGE_U0_SHARED



#define _PAGE_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED | _PAGE_DIRTY)

#define _KERNPG_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)

#define _PAGE_CHG_MASK	(PTE_MASK | _PAGE_ACCESSED | _PAGE_CACHABLE | _PAGE_DIRTY | _PAGE_SHARED)

#define _PAGE_CHG_MASK	(PTE_MASK | _PAGE_ACCESSED | _PAGE_CACHABLE | _PAGE_DIRTY)



#ifndef __ASSEMBLY__



#ifdef CONFIG_MMU

#define PAGE_NONE	__pgprot(_PAGE_PROTNONE | _PAGE_CACHABLE |_PAGE_ACCESSED | _PAGE_FLAGS_HARD)

#define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_CACHABLE |_PAGE_ACCESSED | _PAGE_SHARED | _PAGE_FLAGS_HARD)

#define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_CACHABLE |_PAGE_ACCESSED | _PAGE_FLAGS_HARD)

#define PAGE_COPY	__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_CACHABLE | _PAGE_ACCESSED | _PAGE_FLAGS_HARD)

#define PAGE_READONLY	__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_CACHABLE | _PAGE_ACCESSED | _PAGE_FLAGS_HARD)

#define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_CACHABLE | _PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_HW_SHARED | _PAGE_FLAGS_HARD)