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Kernel
提交 01858d1b 编写于 作者: C Chris Zankel
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[XTENSA] Add support for executable/non-executable feature in the mmu 

Newer processor versions starting with Xtensa6/LX2 support an 'executable'
bit for memory pages. This bit replaces the 'valid' bit, so it must be
always set to one for older processor versions. To mark a page invalid, we now
set the cache-attributes to b11, which is backward compatible.
Signed-off-by: NChris Zankel <chris@zankel.net>
上级 26465f2f
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arch/xtensa/kernel/entry.S
浏览文件 @ 01858d1b
......@@ -1572,10 +1572,12 @@ ENTRY(fast_second_level_miss)
l32i a0, a1, TASK_MM # tsk->mm
beqz a0, 9f
8: rsr a1, EXCVADDR # fault address
_PGD_OFFSET(a0, a1, a1)
/* We deliberately destroy a3 that holds the exception table. */
8: rsr a3, EXCVADDR # fault address
_PGD_OFFSET(a0, a3, a1)
l32i a0, a0, 0 # read pmdval
//beqi a0, _PAGE_USER, 2f
beqz a0, 2f
/* Read ptevaddr and convert to top of page-table page.
......@@ -1596,20 +1598,34 @@ ENTRY(fast_second_level_miss)
extui a1, a0, 0, PAGE_SHIFT # ... & PAGE_MASK
xor a0, a0, a1
movi a1, PAGE_DIRECTORY
movi a1, _PAGE_DIRECTORY
or a0, a0, a1 # ... | PAGE_DIRECTORY
/*
* We utilize all three wired-ways (7-9( to hold pmd translations.
* Memory regions are mapped to the DTLBs according to bits 28 and 29.
* This allows to map the three most common regions to three different
* DTLBs:
* 0,1 -> way 7 program (0040.0000) and virtual (c000.0000)
* 2 -> way 8 shared libaries (2000.0000)
* 3 -> way 0 stack (3000.0000)
*/
extui a3, a3, 28, 2 # addr. bit 28 and 29 0,1,2,3
rsr a1, PTEVADDR
addx2 a3, a3, a3 # -> 0,3,6,9
srli a1, a1, PAGE_SHIFT
extui a3, a3, 2, 2 # -> 0,0,1,2
slli a1, a1, PAGE_SHIFT # ptevaddr & PAGE_MASK
addi a1, a1, DTLB_WAY_PGD # ... + way_number
addi a3, a3, DTLB_WAY_PGD
add a1, a1, a3 # ... + way_number
wdtlb a0, a1
3: wdtlb a0, a1
dsync
/* Exit critical section. */
4: movi a3, exc_table # restore a3
movi a0, 0
s32i a0, a3, EXC_TABLE_FIXUP
......@@ -1638,6 +1654,7 @@ ENTRY(fast_second_level_miss)
2: /* Invalid PGD, default exception handling */
movi a3, exc_table
rsr a1, DEPC
xsr a3, EXCSAVE_1
s32i a1, a2, PT_AREG2
......@@ -1682,15 +1699,15 @@ ENTRY(fast_store_prohibited)
8: rsr a1, EXCVADDR # fault address
_PGD_OFFSET(a0, a1, a4)
l32i a0, a0, 0
//beqi a0, _PAGE_USER, 2f # FIXME use _PAGE_INVALID
beqz a0, 2f
/* Note that we assume _PAGE_WRITABLE_BIT is only set if pte is valid.*/
_PTE_OFFSET(a0, a1, a4)
l32i a4, a0, 0 # read pteval
movi a1, _PAGE_VALID | _PAGE_RW
bnall a4, a1, 2f
bbci.l a4, _PAGE_WRITABLE_BIT, 2f
movi a1, _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_WRENABLE
movi a1, _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_HW_WRITE
or a4, a4, a1
rsr a1, EXCVADDR
s32i a4, a0, 0
......@@ -1700,10 +1717,7 @@ ENTRY(fast_store_prohibited)
dhwb a0, 0
#endif
pdtlb a0, a1
beqz a0, 1f
idtlb a0 // FIXME do we need this?
wdtlb a4, a0
1:
/* Exit critical section. */
......
include/asm-xtensa/pgtable.h
浏览文件 @ 01858d1b
......@@ -2,10 +2,10 @@
* linux/include/asm-xtensa/pgtable.h
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version2 as
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
* Copyright (C) 2001 - 2007 Tensilica Inc.
*/
#ifndef _XTENSA_PGTABLE_H
......@@ -23,7 +23,7 @@
/*
* The Xtensa architecture port of Linux has a two-level page table system,
* i.e. the logical three-level Linux page table layout are folded.
* i.e. the logical three-level Linux page table layout is folded.
* Each task has the following memory page tables:
*
* PGD table (page directory), ie. 3rd-level page table:
......@@ -43,6 +43,7 @@
*
* The individual pages are 4 kB big with special pages for the empty_zero_page.
*/
#define PGDIR_SHIFT 22
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE-1))
......@@ -53,10 +54,8 @@
*/
#define PTRS_PER_PTE 1024
#define PTRS_PER_PTE_SHIFT 10
#define PTRS_PER_PMD 1
#define PTRS_PER_PGD 1024
#define PGD_ORDER 0
#define PMD_ORDER 0
#define USER_PTRS_PER_PGD (TASK_SIZE/PGDIR_SIZE)
#define FIRST_USER_ADDRESS 0
#define FIRST_USER_PGD_NR (FIRST_USER_ADDRESS >> PGDIR_SHIFT)
......@@ -86,47 +85,54 @@
* See further below for PTE layout for swapped-out pages.
*/
#define _PAGE_VALID (1<<0) /* hardware: page is accessible */
#define _PAGE_WRENABLE (1<<1) /* hardware: page is writable */
#define _PAGE_HW_EXEC (1<<0) /* hardware: page is executable */
#define _PAGE_HW_WRITE (1<<1) /* hardware: page is writable */
#define _PAGE_FILE (1<<1) /* non-linear mapping, if !present */
#define _PAGE_PROTNONE (3<<0) /* special case for VM_PROT_NONE */
/* None of these cache modes include MP coherency: */
#define _PAGE_NO_CACHE (0<<2) /* bypass, non-speculative */
#if XCHAL_DCACHE_IS_WRITEBACK
# define _PAGE_WRITEBACK (1<<2) /* write back */
# define _PAGE_WRITETHRU (2<<2) /* write through */
#else
# define _PAGE_WRITEBACK (1<<2) /* assume write through */
# define _PAGE_WRITETHRU (1<<2)
#endif
#define _PAGE_NOALLOC (3<<2) /* don't allocate cache,if not cached */
#define _CACHE_MASK (3<<2)
#define _PAGE_CA_BYPASS (0<<2) /* bypass, non-speculative */
#define _PAGE_CA_WB (1<<2) /* write-back */
#define _PAGE_CA_WT (2<<2) /* write-through */
#define _PAGE_CA_MASK (3<<2)
#define _PAGE_INVALID (3<<2)
#define _PAGE_USER (1<<4) /* user access (ring=1) */
#define _PAGE_KERNEL (0<<4) /* kernel access (ring=0) */
/* Software */
#define _PAGE_RW (1<<6) /* software: page writable */
#define _PAGE_WRITABLE_BIT 6
#define _PAGE_WRITABLE (1<<6) /* software: page writable */
#define _PAGE_DIRTY (1<<7) /* software: page dirty */
#define _PAGE_ACCESSED (1<<8) /* software: page accessed (read) */
#define _PAGE_FILE (1<<9) /* nonlinear file mapping*/
#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _CACHE_MASK | _PAGE_DIRTY)
#define _PAGE_PRESENT ( _PAGE_VALID | _PAGE_WRITEBACK | _PAGE_ACCESSED)
/* On older HW revisions, we always have to set bit 0 */
#if XCHAL_HW_VERSION_MAJOR < 2000
# define _PAGE_VALID (1<<0)
#else
# define _PAGE_VALID 0
#endif
#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
#define _PAGE_PRESENT (_PAGE_VALID | _PAGE_CA_WB | _PAGE_ACCESSED)
#ifdef CONFIG_MMU
# define PAGE_NONE __pgprot(_PAGE_PRESENT)
# define PAGE_SHARED __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_RW)
# define PAGE_COPY __pgprot(_PAGE_PRESENT | _PAGE_USER)
# define PAGE_READONLY __pgprot(_PAGE_PRESENT | _PAGE_USER)
# define PAGE_KERNEL __pgprot(_PAGE_PRESENT | _PAGE_KERNEL | _PAGE_WRENABLE)
# define PAGE_INVALID __pgprot(_PAGE_USER)
# if (DCACHE_WAY_SIZE > PAGE_SIZE)
# define PAGE_DIRECTORY __pgprot(_PAGE_VALID | _PAGE_ACCESSED | _PAGE_KERNEL)
# else
# define PAGE_DIRECTORY __pgprot(_PAGE_PRESENT | _PAGE_KERNEL)
# endif
#define PAGE_NONE __pgprot(_PAGE_INVALID | _PAGE_USER | _PAGE_PROTNONE)
#define PAGE_COPY __pgprot(_PAGE_PRESENT | _PAGE_USER)
#define PAGE_COPY_EXEC __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_HW_EXEC)
#define PAGE_READONLY __pgprot(_PAGE_PRESENT | _PAGE_USER)
#define PAGE_READONLY_EXEC __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_HW_EXEC)
#define PAGE_SHARED __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_WRITABLE)
#define PAGE_SHARED_EXEC \
__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_WRITABLE | _PAGE_HW_EXEC)
#define PAGE_KERNEL __pgprot(_PAGE_PRESENT)
#if (DCACHE_WAY_SIZE > PAGE_SIZE)
# define _PAGE_DIRECTORY (_PAGE_VALID | _PAGE_ACCESSED | _PAGE_HW_WRITE)
#else
# define _PAGE_DIRECTORY (_PAGE_VALID|_PAGE_ACCESSED|_PAGE_HW_WRITE|_PAGE_CA_WB)
#endif
#else /* no mmu */
......@@ -149,19 +155,19 @@
#define __P001 PAGE_READONLY /* private --r */
#define __P010 PAGE_COPY /* private -w- */
#define __P011 PAGE_COPY /* private -wr */
#define __P100 PAGE_READONLY /* private x-- */
#define __P101 PAGE_READONLY /* private x-r */
#define __P110 PAGE_COPY /* private xw- */
#define __P111 PAGE_COPY /* private xwr */
#define __P100 PAGE_READONLY_EXEC /* private x-- */
#define __P101 PAGE_READONLY_EXEC /* private x-r */
#define __P110 PAGE_COPY_EXEC /* private xw- */
#define __P111 PAGE_COPY_EXEC /* private xwr */
#define __S000 PAGE_NONE /* shared --- */
#define __S001 PAGE_READONLY /* shared --r */
#define __S010 PAGE_SHARED /* shared -w- */
#define __S011 PAGE_SHARED /* shared -wr */
#define __S100 PAGE_READONLY /* shared x-- */
#define __S101 PAGE_READONLY /* shared x-r */
#define __S110 PAGE_SHARED /* shared xw- */
#define __S111 PAGE_SHARED /* shared xwr */
#define __S100 PAGE_READONLY_EXEC /* shared x-- */
#define __S101 PAGE_READONLY_EXEC /* shared x-r */
#define __S110 PAGE_SHARED_EXEC /* shared xw- */
#define __S111 PAGE_SHARED_EXEC /* shared xwr */
#ifndef __ASSEMBLY__
......@@ -183,35 +189,42 @@ extern pgd_t swapper_pg_dir[PAGE_SIZE/sizeof(pgd_t)];
#define pmd_page(pmd) virt_to_page(pmd_val(pmd))
/*
* The following only work if pte_present() is true.
* pte status.
*/
#define pte_none(pte) (!(pte_val(pte) ^ _PAGE_USER))
#define pte_present(pte) (pte_val(pte) & _PAGE_VALID)
#define pte_none(pte) (pte_val(pte) == _PAGE_INVALID)
#define pte_present(pte) \
(((pte_val(pte) & _PAGE_CA_MASK) != _PAGE_INVALID) \
|| ((pte_val(pte) & _PAGE_PROTNONE) == _PAGE_PROTNONE))
#define pte_clear(mm,addr,ptep) \
do { update_pte(ptep, __pte(_PAGE_USER)); } while(0)
do { update_pte(ptep, __pte(_PAGE_INVALID)); } while(0)
#define pmd_none(pmd) (!pmd_val(pmd))
#define pmd_present(pmd) (pmd_val(pmd) & PAGE_MASK)
#define pmd_clear(pmdp) do { set_pmd(pmdp, __pmd(0)); } while (0)
#define pmd_bad(pmd) (pmd_val(pmd) & ~PAGE_MASK)
#define pmd_clear(pmdp) do { set_pmd(pmdp, __pmd(0)); } while (0)
/* Note: We use the _PAGE_USER bit to indicate write-protect kernel memory */
static inline int pte_write(pte_t pte) { return pte_val(pte) & _PAGE_RW; }
static inline int pte_write(pte_t pte) { return pte_val(pte) & _PAGE_WRITABLE; }
static inline int pte_dirty(pte_t pte) { return pte_val(pte) & _PAGE_DIRTY; }
static inline int pte_young(pte_t pte) { return pte_val(pte) & _PAGE_ACCESSED; }
static inline int pte_file(pte_t pte) { return pte_val(pte) & _PAGE_FILE; }
static inline pte_t pte_wrprotect(pte_t pte) { pte_val(pte) &= ~(_PAGE_RW | _PAGE_WRENABLE); return pte; }
static inline pte_t pte_mkclean(pte_t pte) { pte_val(pte) &= ~_PAGE_DIRTY; return pte; }
static inline pte_t pte_mkold(pte_t pte) { pte_val(pte) &= ~_PAGE_ACCESSED; return pte; }
static inline pte_t pte_mkdirty(pte_t pte) { pte_val(pte) |= _PAGE_DIRTY; return pte; }
static inline pte_t pte_mkyoung(pte_t pte) { pte_val(pte) |= _PAGE_ACCESSED; return pte; }
static inline pte_t pte_mkwrite(pte_t pte) { pte_val(pte) |= _PAGE_RW; return pte; }
static inline pte_t pte_wrprotect(pte_t pte)
{ pte_val(pte) &= ~(_PAGE_WRITABLE | _PAGE_HW_WRITE); return pte; }
static inline pte_t pte_mkclean(pte_t pte)
{ pte_val(pte) &= ~(_PAGE_DIRTY | _PAGE_HW_WRITE); return pte; }
static inline pte_t pte_mkold(pte_t pte)
{ pte_val(pte) &= ~_PAGE_ACCESSED; return pte; }
static inline pte_t pte_mkdirty(pte_t pte)
{ pte_val(pte) |= _PAGE_DIRTY; return pte; }
static inline pte_t pte_mkyoung(pte_t pte)
{ pte_val(pte) |= _PAGE_ACCESSED; return pte; }
static inline pte_t pte_mkwrite(pte_t pte)
{ pte_val(pte) |= _PAGE_WRITABLE; return pte; }
/*
* Conversion functions: convert a page and protection to a page entry,
* and a page entry and page directory to the page they refer to.
*/
#define pte_pfn(pte) (pte_val(pte) >> PAGE_SHIFT)
#define pte_same(a,b) (pte_val(a) == pte_val(b))
#define pte_page(x) pfn_to_page(pte_pfn(x))
......@@ -231,9 +244,6 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
static inline void update_pte(pte_t *ptep, pte_t pteval)
{
*ptep = pteval;
#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK
__asm__ __volatile__ ("memw; dhwb %0, 0; dsync" :: "a" (ptep));
#endif
}
struct mm_struct;
......@@ -249,9 +259,6 @@ static inline void
set_pmd(pmd_t *pmdp, pmd_t pmdval)
{
*pmdp = pmdval;
#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK
__asm__ __volatile__ ("memw; dhwb %0, 0; dsync" :: "a" (pmdp));
#endif
}
struct vm_area_struct;
......@@ -306,52 +313,34 @@ ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
/*
* Encode and decode a swap entry.
* Each PTE in a process VM's page table is either:
* "present" -- valid and not swapped out, protection bits are meaningful;
* "not present" -- which further subdivides in these two cases:
* "none" -- no mapping at all; identified by pte_none(), set by pte_clear(
* "swapped out" -- the page is swapped out, and the SWP macros below
* are used to store swap file info in the PTE itself.
*
* In the Xtensa processor MMU, any PTE entries in user space (or anywhere
* in virtual memory that can map differently across address spaces)
* must have a correct ring value that represents the RASID field that
* is changed when switching address spaces. Eg. such PTE entries cannot
* be set to ring zero, because that can cause a (global) kernel ASID
* entry to be created in the TLBs (even with invalid cache attribute),
* potentially causing a multihit exception when going back to another
* address space that mapped the same virtual address at another ring.
*
* SO: we avoid using ring bits (_PAGE_RING_MASK) in "not present" PTEs.
* We also avoid using the _PAGE_VALID bit which must be zero for non-present
* pages.
*
* We end up with the following available bits: 1..3 and 7..31.
* We don't bother with 1..3 for now (we can use them later if needed),
* and chose to allocate 6 bits for SWP_TYPE and the remaining 19 bits
* for SWP_OFFSET. At least 5 bits are needed for SWP_TYPE, because it
* is currently implemented as an index into swap_info[MAX_SWAPFILES]
* and MAX_SWAPFILES is currently defined as 32 in <linux/swap.h>.
* However, for some reason all other architectures in the 2.4 kernel
* reserve either 6, 7, or 8 bits so I'll not detract from that for now. :)
* SWP_OFFSET is an offset into the swap file in page-size units, so
* with 4 kB pages, 19 bits supports a maximum swap file size of 2 GB.
*
* FIXME: 2 GB isn't very big. Other bits can be used to allow
* larger swap sizes. In the meantime, it appears relatively easy to get
* around the 2 GB limitation by simply using multiple swap files.
* Format of swap pte:
* bit 0 MBZ
* bit 1 page-file (must be zero)
* bits 2 - 3 page hw access mode (must be 11: _PAGE_INVALID)
* bits 4 - 5 ring protection (must be 01: _PAGE_USER)
* bits 6 - 10 swap type (5 bits -> 32 types)
* bits 11 - 31 swap offset / PAGE_SIZE (21 bits -> 8GB)
* Format of file pte:
* bit 0 MBZ
* bit 1 page-file (must be one: _PAGE_FILE)
* bits 2 - 3 page hw access mode (must be 11: _PAGE_INVALID)
* bits 4 - 5 ring protection (must be 01: _PAGE_USER)
* bits 6 - 31 file offset / PAGE_SIZE
*/
#define __swp_type(entry) (((entry).val >> 7) & 0x3f)
#define __swp_offset(entry) ((entry).val >> 13)
#define __swp_entry(type,offs) ((swp_entry_t) {((type) << 7) | ((offs) << 13)})
#define __swp_type(entry) (((entry).val >> 6) & 0x1f)
#define __swp_offset(entry) ((entry).val >> 11)
#define __swp_entry(type,offs) \
((swp_entry_t) {((type) << 6) | ((offs) << 11) | _PAGE_INVALID})
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
#define PTE_FILE_MAX_BITS 29
#define pte_to_pgoff(pte) (pte_val(pte) >> 3)
#define pgoff_to_pte(off) ((pte_t) { ((off) << 3) | _PAGE_FILE })
#define PTE_FILE_MAX_BITS 28
#define pte_to_pgoff(pte) (pte_val(pte) >> 4)
#define pgoff_to_pte(off) \
((pte_t) { ((off) << 4) | _PAGE_INVALID | _PAGE_FILE })
#endif /* !defined (__ASSEMBLY__) */
......
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