diff options
| author | Ram Pai <linuxram@us.ibm.com> | 2017-11-06 00:50:50 -0800 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-12-20 18:57:24 +1100 |
| commit | 273b49368966559dd155323c64ec3421e8f4049d (patch) | |
| tree | 04d08f2bae13229e9ab4ebbd564ecc38bf70ea4b /arch/powerpc/include/asm/book3s/64/hash.h | |
| parent | 7b84947cadf18f9a7763f281509db1f24073b4af (diff) | |
powerpc: Swizzle around 4K PTE bits to free up bit 5 and bit 6
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>
Diffstat (limited to 'arch/powerpc/include/asm/book3s/64/hash.h')
| -rw-r--r-- | arch/powerpc/include/asm/book3s/64/hash.h | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h index e72474f13936..0920eff731b3 100644 --- a/arch/powerpc/include/asm/book3s/64/hash.h +++ b/arch/powerpc/include/asm/book3s/64/hash.h @@ -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> |