diff options
Diffstat (limited to 'arch/powerpc/include/asm/nohash/32/pte-40x.h')
| -rw-r--r-- | arch/powerpc/include/asm/nohash/32/pte-40x.h | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/nohash/32/pte-40x.h b/arch/powerpc/include/asm/nohash/32/pte-40x.h new file mode 100644 index 000000000..bb4b3a4b9 --- /dev/null +++ b/arch/powerpc/include/asm/nohash/32/pte-40x.h @@ -0,0 +1,62 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_POWERPC_NOHASH_32_PTE_40x_H +#define _ASM_POWERPC_NOHASH_32_PTE_40x_H +#ifdef __KERNEL__ + +/* + * At present, all PowerPC 400-class processors share a similar TLB + * architecture. The instruction and data sides share a unified, + * 64-entry, fully-associative TLB which is maintained totally under + * software control. In addition, the instruction side has a + * hardware-managed, 4-entry, fully-associative TLB which serves as a + * first level to the shared TLB. These two TLBs are known as the UTLB + * and ITLB, respectively (see "mmu.h" for definitions). + * + * There are several potential gotchas here. The 40x hardware TLBLO + * field looks like this: + * + * 0 1 2 3 4 ... 18 19 20 21 22 23 24 25 26 27 28 29 30 31 + * RPN..................... 0 0 EX WR ZSEL....... W I M G + * + * Where possible we make the Linux PTE bits match up with this + * + * - bits 20 and 21 must be cleared, because we use 4k pages (40x can + * support down to 1k pages), this is done in the TLBMiss exception + * handler. + * - We use only zones 0 (for kernel pages) and 1 (for user pages) + * of the 16 available. Bit 24-26 of the TLB are cleared in the TLB + * miss handler. Bit 27 is PAGE_USER, thus selecting the correct + * zone. + * - PRESENT *must* be in the bottom two bits because swap cache + * entries use the top 30 bits. Because 40x doesn't support SMP + * anyway, M is irrelevant so we borrow it for PAGE_PRESENT. Bit 30 + * is cleared in the TLB miss handler before the TLB entry is loaded. + * - All other bits of the PTE are loaded into TLBLO without + * modification, leaving us only the bits 20, 21, 24, 25, 26, 30 for + * software PTE bits. We actually use use bits 21, 24, 25, and + * 30 respectively for the software bits: ACCESSED, DIRTY, RW, and + * PRESENT. + */ + +#define _PAGE_GUARDED 0x001 /* G: page is guarded from prefetch */ +#define _PAGE_PRESENT 0x002 /* software: PTE contains a translation */ +#define _PAGE_NO_CACHE 0x004 /* I: caching is inhibited */ +#define _PAGE_WRITETHRU 0x008 /* W: caching is write-through */ +#define _PAGE_USER 0x010 /* matches one of the zone permission bits */ +#define _PAGE_SPECIAL 0x020 /* software: Special page */ +#define _PAGE_RW 0x040 /* software: Writes permitted */ +#define _PAGE_DIRTY 0x080 /* software: dirty page */ +#define _PAGE_HWWRITE 0x100 /* hardware: Dirty & RW, set in exception */ +#define _PAGE_EXEC 0x200 /* hardware: EX permission */ +#define _PAGE_ACCESSED 0x400 /* software: R: page referenced */ + +#define _PMD_PRESENT 0x400 /* PMD points to page of PTEs */ +#define _PMD_BAD 0x802 +#define _PMD_SIZE_4M 0x0c0 +#define _PMD_SIZE_16M 0x0e0 + +/* Until my rework is finished, 40x still needs atomic PTE updates */ +#define PTE_ATOMIC_UPDATES 1 + +#endif /* __KERNEL__ */ +#endif /* _ASM_POWERPC_NOHASH_32_PTE_40x_H */ |