xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

s390/mm: implement software referenced bits

Browse Source 
The last remaining use for the storage key of the s390 architecture
is reference counting. The alternative is to make page table entries
invalid while they are old. On access the fault handler marks the
pte/pmd as young which makes the pte/pmd valid if the access rights
allow read access. The pte/pmd invalidations required for software
managed reference bits cost a bit of performance, on the other hand
the RRBE/RRBM instructions to read and reset the referenced bits are
quite expensive as well.

Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2013-07-23 22:11:42 +02:00
parent fbd70035fb
commit 0944fe3f4a
7 changed files with 243 additions and 193 deletions
Download Patch File Download Diff File Expand all files Collapse all files

58
arch/s390/mm/hugetlbpage.c
View File

@@ -10,19 +10,25 @@
static inline pmd_t __pte_to_pmd(pte_t pte)
{
int none, prot;
int none, young, prot;
pmd_t pmd;
/*
* Convert encoding pte bits pmd bits
* .IR.....wdtp ..R...I.....
* empty .10.....0000 -> ..0...1.....
* prot-none, clean .11.....0001 -> ..1...1.....
* prot-none, dirty .10.....0101 -> ..1...1.....
* read-only, clean .01.....0001 -> ..1...0.....
* read-only, dirty .01.....0101 -> ..1...0.....
* read-write, clean .01.....1001 -> ..0...0.....
* read-write, dirty .00.....1101 -> ..0...0.....
* Convert encoding pte bits pmd bits
* .IR...wrdytp ..R...I...y.
* empty .10...000000 -> ..0...1...0.
* prot-none, clean, old .11...000001 -> ..0...1...1.
* prot-none, clean, young .11...000101 -> ..1...1...1.
* prot-none, dirty, old .10...001001 -> ..0...1...1.
* prot-none, dirty, young .10...001101 -> ..1...1...1.
* read-only, clean, old .11...010001 -> ..1...1...0.
* read-only, clean, young .01...010101 -> ..1...0...1.
* read-only, dirty, old .11...011001 -> ..1...1...0.
* read-only, dirty, young .01...011101 -> ..1...0...1.
* read-write, clean, old .11...110001 -> ..0...1...0.
* read-write, clean, young .01...110101 -> ..0...0...1.
* read-write, dirty, old .10...111001 -> ..0...1...0.
* read-write, dirty, young .00...111101 -> ..0...0...1.
* Huge ptes are dirty by definition, a clean pte is made dirty
* by the conversion.
*/
@@ -31,9 +37,14 @@ static inline pmd_t __pte_to_pmd(pte_t pte)
if (pte_val(pte) & _PAGE_INVALID)
pmd_val(pmd) |= _SEGMENT_ENTRY_INVALID;
none = (pte_val(pte) & _PAGE_PRESENT) &&
(pte_val(pte) & _PAGE_INVALID);
prot = (pte_val(pte) & _PAGE_PROTECT);
if (prot || none)
!(pte_val(pte) & _PAGE_READ) &&
!(pte_val(pte) & _PAGE_WRITE);
prot = (pte_val(pte) & _PAGE_PROTECT) &&
!(pte_val(pte) & _PAGE_WRITE);
young = pte_val(pte) & _PAGE_YOUNG;
if (none || young)
pmd_val(pmd) |= _SEGMENT_ENTRY_YOUNG;
if (prot || (none && young))
pmd_val(pmd) |= _SEGMENT_ENTRY_PROTECT;
} else
pmd_val(pmd) = _SEGMENT_ENTRY_INVALID;
@@ -46,11 +57,14 @@ static inline pte_t __pmd_to_pte(pmd_t pmd)
/*
* Convert encoding pmd bits pte bits
* ..R...I..... .IR.....wdtp
* empty ..0...1..... -> .10.....0000
* prot-none, young ..1...1..... -> .10.....0101
* read-only, young ..1...0..... -> .01.....0101
* read-write, young ..0...0..... -> .00.....1101
* ..R...I...y. .IR...wrdytp
* empty ..0...1...0. -> .10...000000
* prot-none, old ..0...1...1. -> .10...001001
* prot-none, young ..1...1...1. -> .10...001101
* read-only, old ..1...1...0. -> .11...011001
* read-only, young ..1...0...1. -> .01...011101
* read-write, old ..0...1...0. -> .10...111001
* read-write, young ..0...0...1. -> .00...111101
* Huge ptes are dirty by definition
*/
if (pmd_present(pmd)) {
@@ -58,11 +72,17 @@ static inline pte_t __pmd_to_pte(pmd_t pmd)
(pmd_val(pmd) & PAGE_MASK);
if (pmd_val(pmd) & _SEGMENT_ENTRY_INVALID)
pte_val(pte) |= _PAGE_INVALID;
else {
if (pmd_prot_none(pmd)) {
if (pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT)
pte_val(pte) |= _PAGE_YOUNG;
} else {
pte_val(pte) |= _PAGE_READ;
if (pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT)
pte_val(pte) |= _PAGE_PROTECT;
else
pte_val(pte) |= _PAGE_WRITE;
if (pmd_val(pmd) & _SEGMENT_ENTRY_YOUNG)
pte_val(pte) |= _PAGE_YOUNG;
}
} else
pte_val(pte) = _PAGE_INVALID;