1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_POWERPC_NOHASH_32_PTE_40x_H 3 #define _ASM_POWERPC_NOHASH_32_PTE_40x_H 4 #ifdef __KERNEL__ 5 6 /* 7 * At present, all PowerPC 400-class processors share a similar TLB 8 * architecture. The instruction and data sides share a unified, 9 * 64-entry, fully-associative TLB which is maintained totally under 10 * software control. In addition, the instruction side has a 11 * hardware-managed, 4-entry, fully-associative TLB which serves as a 12 * first level to the shared TLB. These two TLBs are known as the UTLB 13 * and ITLB, respectively (see "mmu.h" for definitions). 14 * 15 * There are several potential gotchas here. The 40x hardware TLBLO 16 * field looks like this: 17 * 18 * 0 1 2 3 4 ... 18 19 20 21 22 23 24 25 26 27 28 29 30 31 19 * RPN..................... 0 0 EX WR ZSEL....... W I M G 20 * 21 * Where possible we make the Linux PTE bits match up with this 22 * 23 * - bits 20 and 21 must be cleared, because we use 4k pages (40x can 24 * support down to 1k pages), this is done in the TLBMiss exception 25 * handler. 26 * - We use only zones 0 (for kernel pages) and 1 (for user pages) 27 * of the 16 available. Bit 24-26 of the TLB are cleared in the TLB 28 * miss handler. Bit 27 is PAGE_USER, thus selecting the correct 29 * zone. 30 * - PRESENT *must* be in the bottom two bits because swap PTEs 31 * use the top 30 bits. Because 40x doesn't support SMP anyway, M is 32 * irrelevant so we borrow it for PAGE_PRESENT. Bit 30 33 * is cleared in the TLB miss handler before the TLB entry is loaded. 34 * - All other bits of the PTE are loaded into TLBLO without 35 * modification, leaving us only the bits 20, 21, 24, 25, 26, 30 for 36 * software PTE bits. We actually use bits 21, 24, 25, and 37 * 30 respectively for the software bits: ACCESSED, DIRTY, RW, and 38 * PRESENT. 39 */ 40 41 #define _PAGE_GUARDED 0x001 /* G: page is guarded from prefetch */ 42 #define _PAGE_PRESENT 0x002 /* software: PTE contains a translation */ 43 #define _PAGE_NO_CACHE 0x004 /* I: caching is inhibited */ 44 #define _PAGE_WRITETHRU 0x008 /* W: caching is write-through */ 45 #define _PAGE_READ 0x010 /* software: read permission */ 46 #define _PAGE_SPECIAL 0x020 /* software: Special page */ 47 #define _PAGE_DIRTY 0x080 /* software: dirty page */ 48 #define _PAGE_WRITE 0x100 /* hardware: WR, anded with dirty in exception */ 49 #define _PAGE_EXEC 0x200 /* hardware: EX permission */ 50 #define _PAGE_ACCESSED 0x400 /* software: R: page referenced */ 51 52 /* No page size encoding in the linux PTE */ 53 #define _PAGE_PSIZE 0 54 55 /* cache related flags non existing on 40x */ 56 #define _PAGE_COHERENT 0 57 58 #define _PMD_PRESENT 0x400 /* PMD points to page of PTEs */ 59 #define _PMD_PRESENT_MASK _PMD_PRESENT 60 #define _PMD_BAD 0x802 61 #define _PMD_SIZE_4M 0x0c0 62 #define _PMD_SIZE_16M 0x0e0 63 #define _PMD_USER 0 64 65 #define _PTE_NONE_MASK 0 66 67 #define _PAGE_BASE_NC (_PAGE_PRESENT | _PAGE_ACCESSED) 68 #define _PAGE_BASE (_PAGE_BASE_NC) 69 70 #include <asm/pgtable-masks.h> 71 72 #endif /* __KERNEL__ */ 73 #endif /* _ASM_POWERPC_NOHASH_32_PTE_40x_H */ 74