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88 lines
3.7 KiB
88 lines
3.7 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef _ASM_POWERPC_NOHASH_32_PTE_40x_H |
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#define _ASM_POWERPC_NOHASH_32_PTE_40x_H |
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#ifdef __KERNEL__ |
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/* |
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* At present, all PowerPC 400-class processors share a similar TLB |
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* architecture. The instruction and data sides share a unified, |
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* 64-entry, fully-associative TLB which is maintained totally under |
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* software control. In addition, the instruction side has a |
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* hardware-managed, 4-entry, fully-associative TLB which serves as a |
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* first level to the shared TLB. These two TLBs are known as the UTLB |
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* and ITLB, respectively (see "mmu.h" for definitions). |
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* |
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* There are several potential gotchas here. The 40x hardware TLBLO |
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* field looks like this: |
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* |
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* 0 1 2 3 4 ... 18 19 20 21 22 23 24 25 26 27 28 29 30 31 |
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* RPN..................... 0 0 EX WR ZSEL....... W I M G |
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* |
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* Where possible we make the Linux PTE bits match up with this |
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* |
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* - bits 20 and 21 must be cleared, because we use 4k pages (40x can |
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* support down to 1k pages), this is done in the TLBMiss exception |
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* handler. |
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* - We use only zones 0 (for kernel pages) and 1 (for user pages) |
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* of the 16 available. Bit 24-26 of the TLB are cleared in the TLB |
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* miss handler. Bit 27 is PAGE_USER, thus selecting the correct |
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* zone. |
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* - PRESENT *must* be in the bottom two bits because swap cache |
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* entries use the top 30 bits. Because 40x doesn't support SMP |
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* anyway, M is irrelevant so we borrow it for PAGE_PRESENT. Bit 30 |
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* is cleared in the TLB miss handler before the TLB entry is loaded. |
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* - All other bits of the PTE are loaded into TLBLO without |
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* modification, leaving us only the bits 20, 21, 24, 25, 26, 30 for |
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* software PTE bits. We actually use bits 21, 24, 25, and |
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* 30 respectively for the software bits: ACCESSED, DIRTY, RW, and |
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* PRESENT. |
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*/ |
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#define _PAGE_GUARDED 0x001 /* G: page is guarded from prefetch */ |
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#define _PAGE_PRESENT 0x002 /* software: PTE contains a translation */ |
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#define _PAGE_NO_CACHE 0x004 /* I: caching is inhibited */ |
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#define _PAGE_WRITETHRU 0x008 /* W: caching is write-through */ |
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#define _PAGE_USER 0x010 /* matches one of the zone permission bits */ |
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#define _PAGE_SPECIAL 0x020 /* software: Special page */ |
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#define _PAGE_DIRTY 0x080 /* software: dirty page */ |
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#define _PAGE_RW 0x100 /* hardware: WR, anded with dirty in exception */ |
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#define _PAGE_EXEC 0x200 /* hardware: EX permission */ |
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#define _PAGE_ACCESSED 0x400 /* software: R: page referenced */ |
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/* No page size encoding in the linux PTE */ |
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#define _PAGE_PSIZE 0 |
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/* cache related flags non existing on 40x */ |
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#define _PAGE_COHERENT 0 |
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#define _PAGE_KERNEL_RO 0 |
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#define _PAGE_KERNEL_ROX _PAGE_EXEC |
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#define _PAGE_KERNEL_RW (_PAGE_DIRTY | _PAGE_RW) |
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#define _PAGE_KERNEL_RWX (_PAGE_DIRTY | _PAGE_RW | _PAGE_EXEC) |
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#define _PMD_PRESENT 0x400 /* PMD points to page of PTEs */ |
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#define _PMD_PRESENT_MASK _PMD_PRESENT |
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#define _PMD_BAD 0x802 |
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#define _PMD_SIZE_4M 0x0c0 |
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#define _PMD_SIZE_16M 0x0e0 |
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#define _PMD_USER 0 |
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#define _PTE_NONE_MASK 0 |
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/* Until my rework is finished, 40x still needs atomic PTE updates */ |
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#define PTE_ATOMIC_UPDATES 1 |
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#define _PAGE_BASE_NC (_PAGE_PRESENT | _PAGE_ACCESSED) |
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#define _PAGE_BASE (_PAGE_BASE_NC) |
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/* Permission masks used to generate the __P and __S table */ |
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#define PAGE_NONE __pgprot(_PAGE_BASE) |
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#define PAGE_SHARED __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW) |
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#define PAGE_SHARED_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW | _PAGE_EXEC) |
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#define PAGE_COPY __pgprot(_PAGE_BASE | _PAGE_USER) |
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#define PAGE_COPY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC) |
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#define PAGE_READONLY __pgprot(_PAGE_BASE | _PAGE_USER) |
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#define PAGE_READONLY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC) |
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#endif /* __KERNEL__ */ |
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#endif /* _ASM_POWERPC_NOHASH_32_PTE_40x_H */
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