| /* 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 */ |
