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powerpc: Free up four 64K PTE bits in 64K backed HPTE pages

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Rearrange 64K PTE bits to free up bits 3, 4, 5 and 6
in the 64K backed HPTE pages. This along with the earlier
patch will entirely free up the four bits from 64K PTE.
The bit numbers are big-endian as defined in the ISA3.0

This patch does the following change to 64K PTE backed
by 64K HPTE.

H_PAGE_F_SECOND (S) which occupied bit 4 moves to the
	second part of the pte to bit 60.
H_PAGE_F_GIX (G,I,X) which occupied bit 5, 6 and 7 also
	moves to the second part of the pte to bit 61,
 	62, 63, 64 respectively

since bit 7 is now freed up, we move H_PAGE_BUSY (B) from
bit 9 to bit 7.

The second part of the PTE will hold
(H_PAGE_F_SECOND|H_PAGE_F_GIX) at bit 60,61,62,63.
NOTE: None of the bits in the secondary PTE were not used
by 64k-HPTE backed PTE.

Before the patch, the 64K HPTE backed 64k PTE format was
as follows

 0 1 2 3 4  5  6  7  8 9 10...........................63
 : : : : :  :  :  :  : : :                            :
 v v v v v  v  v  v  v v v                            v

,-,-,-,-,--,--,--,--,-,-,-,-,-,------------------,-,-,-,
|x|x|x| |S |G |I |X |x|B| |x|x|................|x|x|x|x| <- primary pte
'_'_'_'_'__'__'__'__'_'_'_'_'_'________________'_'_'_'_'
| | | | |  |  |  |  | | | | |..................| | | | | <- secondary pte
'_'_'_'_'__'__'__'__'_'_'_'_'__________________'_'_'_'_'

After the patch, the 64k HPTE backed 64k PTE format is
as follows

 0 1 2 3 4  5  6  7  8 9 10...........................63
 : : : : :  :  :  :  : : :                            :
 v v v v v  v  v  v  v v v                            v

,-,-,-,-,--,--,--,--,-,-,-,-,-,------------------,-,-,-,
|x|x|x| |  |  |  |B |x| | |x|x|................|.|.|.|.| <- primary pte
'_'_'_'_'__'__'__'__'_'_'_'_'_'________________'_'_'_'_'
| | | | |  |  |  |  | | | | |..................|S|G|I|X| <- secondary pte
'_'_'_'_'__'__'__'__'_'_'_'_'__________________'_'_'_'_'

The above PTE changes is applicable to hugetlbpages aswell.

The patch does the following code changes:

a) moves the H_PAGE_F_SECOND and H_PAGE_F_GIX to 4k PTE
	header since it is no more needed b the 64k PTEs.
b) abstracts out __real_pte() and __rpte_to_hidx() so the
	caller need not know the bit location of the slot.
c) moves the slot bits to the secondary pte.

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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 00:50:48 -08:00
committed by Michael Ellerman
parent 9d2edb1848
commit bf9a95f9a6
5 changed files with 33 additions and 40 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
arch/powerpc/mm/hash64_64k.c
View File

@@ -103,8 +103,8 @@ int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
* On hash insert failure we use old pte value and we don't
* want slot information there if we have a insert failure.
*/
old_pte &= ~(H_PAGE_HASHPTE | H_PAGE_F_GIX | H_PAGE_F_SECOND);
new_pte &= ~(H_PAGE_HASHPTE | H_PAGE_F_GIX | H_PAGE_F_SECOND);
old_pte &= ~H_PAGE_HASHPTE;
new_pte &= ~H_PAGE_HASHPTE;
goto htab_insert_hpte;
}
/*
@@ -225,6 +225,7 @@ int __hash_page_64K(unsigned long ea, unsigned long access,
unsigned long vsid, pte_t *ptep, unsigned long trap,
unsigned long flags, int ssize)
{
real_pte_t rpte;
unsigned long hpte_group;
unsigned long rflags, pa;
unsigned long old_pte, new_pte;
@@ -261,6 +262,7 @@ int __hash_page_64K(unsigned long ea, unsigned long access,
} while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
rflags = htab_convert_pte_flags(new_pte);
rpte = __real_pte(__pte(old_pte), ptep);
if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
!cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
@@ -268,16 +270,13 @@ int __hash_page_64K(unsigned long ea, unsigned long access,
vpn = hpt_vpn(ea, vsid, ssize);
if (unlikely(old_pte & H_PAGE_HASHPTE)) {
unsigned long gslot;
/*
* There MIGHT be an HPTE for this pte
*/
hash = hpt_hash(vpn, shift, ssize);
if (old_pte & H_PAGE_F_SECOND)
hash = ~hash;
slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
slot += (old_pte & H_PAGE_F_GIX) >> H_PAGE_F_GIX_SHIFT;
if (mmu_hash_ops.hpte_updatepp(slot, rflags, vpn, MMU_PAGE_64K,
gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0);
if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_64K,
MMU_PAGE_64K, ssize,
flags) == -1)
old_pte &= ~_PAGE_HPTEFLAGS;
@@ -326,9 +325,9 @@ repeat:
MMU_PAGE_64K, MMU_PAGE_64K, old_pte);
return -1;
}
new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
new_pte |= (slot << H_PAGE_F_GIX_SHIFT) &
(H_PAGE_F_SECOND | H_PAGE_F_GIX);
new_pte |= pte_set_hidx(ptep, rpte, 0, slot);
}
*ptep = __pte(new_pte & ~H_PAGE_BUSY);
return 0;