ea3cc330ac
This is an attempt at cleaning up a bit the way we handle execute permission on powerpc. _PAGE_HWEXEC is gone, _PAGE_EXEC is now only defined by CPUs that can do something with it, and the myriad of #ifdef's in the I$/D$ coherency code is reduced to 2 cases that hopefully should cover everything. The logic on BookE is a little bit different than what it was though not by much. Since now, _PAGE_EXEC will be set by the generic code for executable pages, we need to filter out if they are unclean and recover it. However, I don't expect the code to be more bloated than it already was in that area due to that change. I could boast that this brings proper enforcing of per-page execute permissions to all BookE and 40x but in fact, we've had that now for some time as a side effect of my previous rework in that area (and I didn't even know it :-) We would only enable execute permission if the page was cache clean and we would only cache clean it if we took and exec fault. Since we now enforce that the later only work if VM_EXEC is part of the VMA flags, we de-fact already enforce per-page execute permissions... Unless I missed something Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
64 lines
2.9 KiB
C
64 lines
2.9 KiB
C
#ifndef _ASM_POWERPC_PTE_40x_H
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#define _ASM_POWERPC_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 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_FILE 0x001 /* when !present: nonlinear file mapping */
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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_RW 0x040 /* software: Writes permitted */
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#define _PAGE_DIRTY 0x080 /* software: dirty page */
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#define _PAGE_HWWRITE 0x100 /* hardware: Dirty & RW, set 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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#define _PMD_PRESENT 0x400 /* PMD points to page of PTEs */
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#define _PMD_BAD 0x802
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#define _PMD_SIZE 0x0e0 /* size field, != 0 for large-page PMD entry */
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#define _PMD_SIZE_4M 0x0c0
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#define _PMD_SIZE_16M 0x0e0
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#define PMD_PAGE_SIZE(pmdval) (1024 << (((pmdval) & _PMD_SIZE) >> 4))
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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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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_PTE_40x_H */
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