65 lines
2.8 KiB
C
Executable file
65 lines
2.8 KiB
C
Executable file
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_POWERPC_NOHASH_32_PTE_8xx_H
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#define _ASM_POWERPC_NOHASH_32_PTE_8xx_H
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#ifdef __KERNEL__
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/*
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* The PowerPC MPC8xx uses a TLB with hardware assisted, software tablewalk.
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* We also use the two level tables, but we can put the real bits in them
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* needed for the TLB and tablewalk. These definitions require Mx_CTR.PPM = 0,
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* Mx_CTR.PPCS = 0, and MD_CTR.TWAM = 1. The level 2 descriptor has
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* additional page protection (when Mx_CTR.PPCS = 1) that allows TLB hit
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* based upon user/super access. The TLB does not have accessed nor write
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* protect. We assume that if the TLB get loaded with an entry it is
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* accessed, and overload the changed bit for write protect. We use
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* two bits in the software pte that are supposed to be set to zero in
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* the TLB entry (24 and 25) for these indicators. Although the level 1
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* descriptor contains the guarded and writethrough/copyback bits, we can
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* set these at the page level since they get copied from the Mx_TWC
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* register when the TLB entry is loaded. We will use bit 27 for guard, since
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* that is where it exists in the MD_TWC, and bit 26 for writethrough.
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* These will get masked from the level 2 descriptor at TLB load time, and
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* copied to the MD_TWC before it gets loaded.
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* Large page sizes added. We currently support two sizes, 4K and 8M.
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* This also allows a TLB hander optimization because we can directly
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* load the PMD into MD_TWC. The 8M pages are only used for kernel
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* mapping of well known areas. The PMD (PGD) entries contain control
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* flags in addition to the address, so care must be taken that the
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* software no longer assumes these are only pointers.
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*/
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/* Definitions for 8xx embedded chips. */
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#define _PAGE_PRESENT 0x0001 /* Page is valid */
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#define _PAGE_NO_CACHE 0x0002 /* I: cache inhibit */
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#define _PAGE_PRIVILEGED 0x0004 /* No ASID (context) compare */
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#define _PAGE_HUGE 0x0008 /* SPS: Small Page Size (1 if 16k, 512k or 8M)*/
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#define _PAGE_DIRTY 0x0100 /* C: page changed */
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/* These 4 software bits must be masked out when the L2 entry is loaded
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* into the TLB.
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*/
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#define _PAGE_GUARDED 0x0010 /* Copied to L1 G entry in DTLB */
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#define _PAGE_SPECIAL 0x0020 /* SW entry */
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#define _PAGE_EXEC 0x0040 /* Copied to PP (bit 21) in ITLB */
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#define _PAGE_ACCESSED 0x0080 /* software: page referenced */
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#define _PAGE_NA 0x0200 /* Supervisor NA, User no access */
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#define _PAGE_RO 0x0600 /* Supervisor RO, User no access */
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#define _PMD_PRESENT 0x0001
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#define _PMD_BAD 0x0fd0
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#define _PMD_PAGE_MASK 0x000c
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#define _PMD_PAGE_8M 0x000c
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#define _PMD_PAGE_512K 0x0004
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#define _PMD_USER 0x0020 /* APG 1 */
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/* Until my rework is finished, 8xx still needs atomic PTE updates */
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#define PTE_ATOMIC_UPDATES 1
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#ifdef CONFIG_PPC_16K_PAGES
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#define _PAGE_PSIZE _PAGE_HUGE
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#endif
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_NOHASH_32_PTE_8xx_H */
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