[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: Chris Zankel <chris@zankel.net>
diff --git a/include/asm-xtensa/pgtable.h b/include/asm-xtensa/pgtable.h
index 06850f3..667a6c4 100644
--- a/include/asm-xtensa/pgtable.h
+++ b/include/asm-xtensa/pgtable.h
@@ -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))
@@ -53,12 +54,10 @@
*/
#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_ADDRESS 0
#define FIRST_USER_PGD_NR (FIRST_USER_ADDRESS >> PGDIR_SHIFT)
/* virtual memory area. We keep a distance to other memory regions to be
@@ -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)
+#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 __pgprot(_PAGE_VALID | _PAGE_ACCESSED | _PAGE_KERNEL)
-# else
-# define PAGE_DIRECTORY __pgprot(_PAGE_PRESENT | _PAGE_KERNEL)
-# endif
+#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 */
@@ -145,23 +151,23 @@
* What follows is the closest we can get by reasonable means..
* See linux/mm/mmap.c for protection_map[] array that uses these definitions.
*/
-#define __P000 PAGE_NONE /* private --- */
-#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 __P000 PAGE_NONE /* private --- */
+#define __P001 PAGE_READONLY /* private --r */
+#define __P010 PAGE_COPY /* private -w- */
+#define __P011 PAGE_COPY /* private -wr */
+#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 __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_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 @@
#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 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 @@
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 @@
/*
* 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__) */