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powerpc: Swizzle around 4K PTE bits to free up bit 5 and bit 6

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We need PTE bits 3 ,4, 5, 6 and 57 to support protection-keys,
because these are the bits we want to consolidate on across all
configuration to support protection keys.

Bit 3,4,5 and 6 are currently used on 4K-pte kernels. But bit 9
and 10 are available. Hence we use the two available bits and
free up bit 5 and 6. We will still not be able to free up bit 3
and 4. In the absence of any other free bits, we will have to
stay satisfied with what we have :-(. This means we will not
be able to support 32 protection keys, but only 8. The bit
numbers are big-endian as defined in the ISA3.0

This patch does the following change to 4K PTE.

H_PAGE_F_SECOND (S) which occupied bit 4 moves to bit 7.
H_PAGE_F_GIX (G,I,X) which occupied bit 5, 6 and 7 also moves
to bit 8,9, 10 respectively.
H_PAGE_HASHPTE (H) which occupied bit 8 moves to bit 4.

Before the patch, the 4k PTE format was as follows

 0 1 2 3 4  5  6  7  8 9 10....................57.....63
 : : : : :  :  :  :  : : :                      :     :
 v v v v v  v  v  v  v v v                      v     v
,-,-,-,-,--,--,--,--,-,-,-,-,-,------------------,-,-,-,
|x|x|x|B|S |G |I |X |H| | |x|x|................| |x|x|x|
'_'_'_'_'__'__'__'__'_'_'_'_'_'________________'_'_'_'_'

After the patch, the 4k PTE format is as follows

 0 1 2 3 4  5  6  7  8 9 10....................57.....63
 : : : : :  :  :  :  : : :                      :     :
 v v v v v  v  v  v  v v v                      v     v
,-,-,-,-,--,--,--,--,-,-,-,-,-,------------------,-,-,-,
|x|x|x|B|H |  |  |S |G|I|X|x|x|................| |.|.|.|
'_'_'_'_'__'__'__'__'_'_'_'_'_'________________'_'_'_'_'

The patch has no code changes; just swizzles around bits.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Ram Pai 2017-11-06 00:50:50 -08:00 committed by Michael Ellerman
parent 7b84947cad
commit 273b493689
3 changed files with 5 additions and 4 deletions
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7
arch/powerpc/include/asm/book3s/64/hash-4k.h
View file

@ -17,10 +17,11 @@
#define H_PUD_TABLE_SIZE (sizeof(pud_t) << H_PUD_INDEX_SIZE)
#define H_PGD_TABLE_SIZE (sizeof(pgd_t) << H_PGD_INDEX_SIZE)
#define H_PAGE_F_GIX_SHIFT 56
#define H_PAGE_F_SECOND _RPAGE_RSV2 /* HPTE is in 2ndary HPTEG */
#define H_PAGE_F_GIX (_RPAGE_RSV3 | _RPAGE_RSV4 | _RPAGE_RPN44)
#define H_PAGE_F_GIX_SHIFT 53
#define H_PAGE_F_SECOND _RPAGE_RPN44 /* HPTE is in 2ndary HPTEG */
#define H_PAGE_F_GIX (_RPAGE_RPN43 | _RPAGE_RPN42 | _RPAGE_RPN41)
#define H_PAGE_BUSY _RPAGE_RSV1 /* software: PTE & hash are busy */
#define H_PAGE_HASHPTE _RPAGE_RSV2 /* software: PTE & hash are busy */
/* PTE flags to conserve for HPTE identification */
#define _PAGE_HPTEFLAGS (H_PAGE_BUSY | H_PAGE_HASHPTE | \

1
arch/powerpc/include/asm/book3s/64/hash-64k.h
View file

@ -14,6 +14,7 @@
#define H_PAGE_COMBO _RPAGE_RPN0 /* this is a combo 4k page */
#define H_PAGE_4K_PFN _RPAGE_RPN1 /* PFN is for a single 4k page */
#define H_PAGE_BUSY _RPAGE_RPN44 /* software: PTE & hash are busy */
#define H_PAGE_HASHPTE _RPAGE_RPN43 /* PTE has associated HPTE */
/*
* We need to differentiate between explicit huge page and THP huge

1
arch/powerpc/include/asm/book3s/64/hash.h
View file

@ -9,7 +9,6 @@
*
*/
#define H_PTE_NONE_MASK _PAGE_HPTEFLAGS
#define H_PAGE_HASHPTE _RPAGE_RPN43 /* PTE has associated HPTE */
#ifdef CONFIG_PPC_64K_PAGES
#include <asm/book3s/64/hash-64k.h>