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linux/arch/mips/include/asm/pgtable-32.h
David Daney 6dd9344cfc MIPS: Implement Read Inhibit/eXecute Inhibit 
The SmartMIPS ASE specifies how Read Inhibit (RI) and eXecute Inhibit
(XI) bits in the page tables work.  The upper two bits of EntryLo{0,1}
are RI and XI when the feature is enabled in the PageGrain register.
SmartMIPS only covers 32-bit systems.  Cavium Octeon+ extends this to
64-bit systems by continuing to place the RI and XI bits in the top of
EntryLo even when EntryLo is 64-bits wide.

Because we need to carry the RI and XI bits in the PTE, the layout of
the PTE is changed.  There is a two instruction overhead in the TLB
refill hot path to get the EntryLo bits into the proper position.
Also the TLB load exception has to probe the TLB to check if RI or XI
caused the exception.

Also of note is that the layout of the PTE bits is done at compile and
runtime rather than statically.  In the 32-bit case this allows for
the same number of PFN bits as before the patch as the _PAGE_HUGE is
not supported in 32-bit kernels (we have _PAGE_NO_EXEC and
_PAGE_NO_READ instead of _PAGE_READ and _PAGE_HUGE).

The patch is tested on Cavium Octeon+, but should also work on 32-bit
systems with the Smart-MIPS ASE.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/952/
Patchwork: http://patchwork.linux-mips.org/patch/956/
Patchwork: http://patchwork.linux-mips.org/patch/962/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2010-02-27 12:53:26 +01:00

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1994, 95, 96, 97, 98, 99, 2000, 2003 Ralf Baechle
* Copyright (C) 1999, 2000, 2001 Silicon Graphics, Inc.
*/
#ifndef _ASM_PGTABLE_32_H
#define _ASM_PGTABLE_32_H
#include <asm/addrspace.h>
#include <asm/page.h>
#include <linux/linkage.h>
#include <asm/cachectl.h>
#include <asm/fixmap.h>
#include <asm-generic/pgtable-nopmd.h>
/*
* - add_wired_entry() add a fixed TLB entry, and move wired register
*/
extern void add_wired_entry(unsigned long entrylo0, unsigned long entrylo1,
unsigned long entryhi, unsigned long pagemask);
/*
* - add_temporary_entry() add a temporary TLB entry. We use TLB entries
* starting at the top and working down. This is for populating the
* TLB before trap_init() puts the TLB miss handler in place. It
* should be used only for entries matching the actual page tables,
* to prevent inconsistencies.
*/
extern int add_temporary_entry(unsigned long entrylo0, unsigned long entrylo1,
unsigned long entryhi, unsigned long pagemask);
/* Basically we have the same two-level (which is the logical three level
* Linux page table layout folded) page tables as the i386. Some day
* when we have proper page coloring support we can have a 1% quicker
* tlb refill handling mechanism, but for now it is a bit slower but
* works even with the cache aliasing problem the R4k and above have.
*/
/* PGDIR_SHIFT determines what a third-level page table entry can map */
#define PGDIR_SHIFT (2 * PAGE_SHIFT + PTE_ORDER - PTE_T_LOG2)
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE-1))
/*
* Entries per page directory level: we use two-level, so
* we don't really have any PUD/PMD directory physically.
*/
#define __PGD_ORDER (32 - 3 * PAGE_SHIFT + PGD_T_LOG2 + PTE_T_LOG2)
#define PGD_ORDER (__PGD_ORDER >= 0 ? __PGD_ORDER : 0)
#define PUD_ORDER aieeee_attempt_to_allocate_pud
#define PMD_ORDER 1
#define PTE_ORDER 0
#define PTRS_PER_PGD (USER_PTRS_PER_PGD * 2)
#define PTRS_PER_PTE ((PAGE_SIZE << PTE_ORDER) / sizeof(pte_t))
#define USER_PTRS_PER_PGD (0x80000000UL/PGDIR_SIZE)
#define FIRST_USER_ADDRESS 0
#define VMALLOC_START MAP_BASE
#define PKMAP_BASE (0xfe000000UL)
#ifdef CONFIG_HIGHMEM
# define VMALLOC_END (PKMAP_BASE-2*PAGE_SIZE)
#else
# define VMALLOC_END (FIXADDR_START-2*PAGE_SIZE)
#endif
#ifdef CONFIG_64BIT_PHYS_ADDR
#define pte_ERROR(e) \
printk("%s:%d: bad pte %016Lx.\n", __FILE__, __LINE__, pte_val(e))
#else
#define pte_ERROR(e) \
printk("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e))
#endif
#define pgd_ERROR(e) \
printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
extern void load_pgd(unsigned long pg_dir);
extern pte_t invalid_pte_table[PAGE_SIZE/sizeof(pte_t)];
/*
* Empty pgd/pmd entries point to the invalid_pte_table.
*/
static inline int pmd_none(pmd_t pmd)
{
return pmd_val(pmd) == (unsigned long) invalid_pte_table;
}
#define pmd_bad(pmd) (pmd_val(pmd) & ~PAGE_MASK)
static inline int pmd_present(pmd_t pmd)
{
return pmd_val(pmd) != (unsigned long) invalid_pte_table;
}
static inline void pmd_clear(pmd_t *pmdp)
{
pmd_val(*pmdp) = ((unsigned long) invalid_pte_table);
}
#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
#define pte_page(x) pfn_to_page(pte_pfn(x))
#define pte_pfn(x) ((unsigned long)((x).pte_high >> 6))
static inline pte_t
pfn_pte(unsigned long pfn, pgprot_t prot)
{
pte_t pte;
pte.pte_high = (pfn << 6) | (pgprot_val(prot) & 0x3f);
pte.pte_low = pgprot_val(prot);
return pte;
}
#else
#define pte_page(x) pfn_to_page(pte_pfn(x))
#ifdef CONFIG_CPU_VR41XX
#define pte_pfn(x) ((unsigned long)((x).pte >> (PAGE_SHIFT + 2)))
#define pfn_pte(pfn, prot) __pte(((pfn) << (PAGE_SHIFT + 2)) | pgprot_val(prot))
#else
#define pte_pfn(x) ((unsigned long)((x).pte >> _PFN_SHIFT))
#define pfn_pte(pfn, prot) __pte(((unsigned long long)(pfn) << _PFN_SHIFT) | pgprot_val(prot))
#endif
#endif /* defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32) */
#define __pgd_offset(address) pgd_index(address)
#define __pud_offset(address) (((address) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
#define __pmd_offset(address) (((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
/* to find an entry in a kernel page-table-directory */
#define pgd_offset_k(address) pgd_offset(&init_mm, address)
#define pgd_index(address) (((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
/* to find an entry in a page-table-directory */
#define pgd_offset(mm, addr) ((mm)->pgd + pgd_index(addr))
/* Find an entry in the third-level page table.. */
#define __pte_offset(address) \
(((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
#define pte_offset(dir, address) \
((pte_t *) pmd_page_vaddr(*(dir)) + __pte_offset(address))
#define pte_offset_kernel(dir, address) \
((pte_t *) pmd_page_vaddr(*(dir)) + __pte_offset(address))
#define pte_offset_map(dir, address) \
((pte_t *)page_address(pmd_page(*(dir))) + __pte_offset(address))
#define pte_offset_map_nested(dir, address) \
((pte_t *)page_address(pmd_page(*(dir))) + __pte_offset(address))
#define pte_unmap(pte) ((void)(pte))
#define pte_unmap_nested(pte) ((void)(pte))
#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
/* Swap entries must have VALID bit cleared. */
#define __swp_type(x) (((x).val >> 10) & 0x1f)
#define __swp_offset(x) ((x).val >> 15)
#define __swp_entry(type,offset) \
((swp_entry_t) { ((type) << 10) | ((offset) << 15) })
/*
* Bits 0, 4, 8, and 9 are taken, split up 28 bits of offset into this range:
*/
#define PTE_FILE_MAX_BITS 28
#define pte_to_pgoff(_pte) ((((_pte).pte >> 1 ) & 0x07) | \
(((_pte).pte >> 2 ) & 0x38) | \
(((_pte).pte >> 10) << 6 ))
#define pgoff_to_pte(off) ((pte_t) { (((off) & 0x07) << 1 ) | \
(((off) & 0x38) << 2 ) | \
(((off) >> 6 ) << 10) | \
_PAGE_FILE })
#else
/* Swap entries must have VALID and GLOBAL bits cleared. */
#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
#define __swp_type(x) (((x).val >> 2) & 0x1f)
#define __swp_offset(x) ((x).val >> 7)
#define __swp_entry(type,offset) \
((swp_entry_t) { ((type) << 2) | ((offset) << 7) })
#else
#define __swp_type(x) (((x).val >> 8) & 0x1f)
#define __swp_offset(x) ((x).val >> 13)
#define __swp_entry(type,offset) \
((swp_entry_t) { ((type) << 8) | ((offset) << 13) })
#endif /* defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32) */
#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
/*
* Bits 0 and 1 of pte_high are taken, use the rest for the page offset...
*/
#define PTE_FILE_MAX_BITS 30
#define pte_to_pgoff(_pte) ((_pte).pte_high >> 2)
#define pgoff_to_pte(off) ((pte_t) { _PAGE_FILE, (off) << 2 })
#else
/*
* Bits 0, 4, 6, and 7 are taken, split up 28 bits of offset into this range:
*/
#define PTE_FILE_MAX_BITS 28
#define pte_to_pgoff(_pte) ((((_pte).pte >> 1) & 0x7) | \
(((_pte).pte >> 2) & 0x8) | \
(((_pte).pte >> 8) << 4))
#define pgoff_to_pte(off) ((pte_t) { (((off) & 0x7) << 1) | \
(((off) & 0x8) << 2) | \
(((off) >> 4) << 8) | \
_PAGE_FILE })
#endif
#endif
#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
#define __pte_to_swp_entry(pte) ((swp_entry_t) { (pte).pte_high })
#define __swp_entry_to_pte(x) ((pte_t) { 0, (x).val })
#else
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
#endif
#endif /* _ASM_PGTABLE_32_H */
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