]> git.ipfire.org Git - thirdparty/linux.git/blob - arch/powerpc/include/asm/book3s/32/hash.h
Merge tag 'io_uring-5.7-2020-05-22' of git://git.kernel.dk/linux-block
[thirdparty/linux.git] / arch / powerpc / include / asm / book3s / 32 / hash.h
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_POWERPC_BOOK3S_32_HASH_H
3 #define _ASM_POWERPC_BOOK3S_32_HASH_H
4 #ifdef __KERNEL__
5
6 /*
7 * The "classic" 32-bit implementation of the PowerPC MMU uses a hash
8 * table containing PTEs, together with a set of 16 segment registers,
9 * to define the virtual to physical address mapping.
10 *
11 * We use the hash table as an extended TLB, i.e. a cache of currently
12 * active mappings. We maintain a two-level page table tree, much
13 * like that used by the i386, for the sake of the Linux memory
14 * management code. Low-level assembler code in hash_low_32.S
15 * (procedure hash_page) is responsible for extracting ptes from the
16 * tree and putting them into the hash table when necessary, and
17 * updating the accessed and modified bits in the page table tree.
18 */
19
20 #define _PAGE_PRESENT 0x001 /* software: pte contains a translation */
21 #define _PAGE_HASHPTE 0x002 /* hash_page has made an HPTE for this pte */
22 #define _PAGE_USER 0x004 /* usermode access allowed */
23 #define _PAGE_GUARDED 0x008 /* G: prohibit speculative access */
24 #define _PAGE_COHERENT 0x010 /* M: enforce memory coherence (SMP systems) */
25 #define _PAGE_NO_CACHE 0x020 /* I: cache inhibit */
26 #define _PAGE_WRITETHRU 0x040 /* W: cache write-through */
27 #define _PAGE_DIRTY 0x080 /* C: page changed */
28 #define _PAGE_ACCESSED 0x100 /* R: page referenced */
29 #define _PAGE_EXEC 0x200 /* software: exec allowed */
30 #define _PAGE_RW 0x400 /* software: user write access allowed */
31 #define _PAGE_SPECIAL 0x800 /* software: Special page */
32
33 #ifdef CONFIG_PTE_64BIT
34 /* We never clear the high word of the pte */
35 #define _PTE_NONE_MASK (0xffffffff00000000ULL | _PAGE_HASHPTE)
36 #else
37 #define _PTE_NONE_MASK _PAGE_HASHPTE
38 #endif
39
40 #define _PMD_PRESENT 0
41 #define _PMD_PRESENT_MASK (PAGE_MASK)
42 #define _PMD_BAD (~PAGE_MASK)
43
44 #endif /* __KERNEL__ */
45 #endif /* _ASM_POWERPC_BOOK3S_32_HASH_H */