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ARCv2: mm: THP support

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MMUv4 in HS38x cores supports Super Pages which are basis for Linux THP
support.

Normal and Super pages can co-exist (ofcourse not overlap) in TLB with a
new bit "SZ" in TLB page desciptor to distinguish between them.
Super Page size is configurable in hardware (4K to 16M), but fixed once
RTL builds.

The exact THP size a Linx configuration will support is a function of:
 - MMU page size (typical 8K, RTL fixed)
 - software page walker address split between PGD:PTE:PFN (typical
   11:8:13, but can be changed with 1 line)

So for above default, THP size supported is 8K * 256 = 2M

Default Page Walker is 2 levels, PGD:PTE:PFN, which in THP regime
reduces to 1 level (as PTE is folded into PGD and canonically referred
to as PMD).

Thus thp PMD accessors are implemented in terms of PTE (just like sparc)

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta
2014-07-08 18:43:47 +05:30
parent 55ad769fde
commit fe6c1b8611
6 changed files with 192 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

81
arch/arc/mm/tlb.c
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@@ -256,6 +256,18 @@ noinline void local_flush_tlb_all(void)
write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
}
if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
const int stlb_idx = 0x800;
/* Blank sTLB entry */
write_aux_reg(ARC_REG_TLBPD0, _PAGE_HW_SZ);
for (entry = stlb_idx; entry < stlb_idx + 16; entry++) {
write_aux_reg(ARC_REG_TLBINDEX, entry);
write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
}
}
utlb_invalidate();
local_irq_restore(flags);
@@ -580,6 +592,75 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long vaddr_unaligned,
}
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/*
* MMUv4 in HS38x cores supports Super Pages which are basis for Linux THP
* support.
*
* Normal and Super pages can co-exist (ofcourse not overlap) in TLB with a
* new bit "SZ" in TLB page desciptor to distinguish between them.
* Super Page size is configurable in hardware (4K to 16M), but fixed once
* RTL builds.
*
* The exact THP size a Linx configuration will support is a function of:
* - MMU page size (typical 8K, RTL fixed)
* - software page walker address split between PGD:PTE:PFN (typical
* 11:8:13, but can be changed with 1 line)
* So for above default, THP size supported is 8K * (2^8) = 2M
*
* Default Page Walker is 2 levels, PGD:PTE:PFN, which in THP regime
* reduces to 1 level (as PTE is folded into PGD and canonically referred
* to as PMD).
* Thus THP PMD accessors are implemented in terms of PTE (just like sparc)
*/
void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr,
pmd_t *pmd)
{
pte_t pte = __pte(pmd_val(*pmd));
update_mmu_cache(vma, addr, &pte);
}
void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
pgtable_t pgtable)
{
struct list_head *lh = (struct list_head *) pgtable;
assert_spin_locked(&mm->page_table_lock);
/* FIFO */
if (!pmd_huge_pte(mm, pmdp))
INIT_LIST_HEAD(lh);
else
list_add(lh, (struct list_head *) pmd_huge_pte(mm, pmdp));
pmd_huge_pte(mm, pmdp) = pgtable;
}
pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
{
struct list_head *lh;
pgtable_t pgtable;
assert_spin_locked(&mm->page_table_lock);
pgtable = pmd_huge_pte(mm, pmdp);
lh = (struct list_head *) pgtable;
if (list_empty(lh))
pmd_huge_pte(mm, pmdp) = NULL;
else {
pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
list_del(lh);
}
pte_val(pgtable[0]) = 0;
pte_val(pgtable[1]) = 0;
return pgtable;
}
#endif
/* Read the Cache Build Confuration Registers, Decode them and save into
* the cpuinfo structure for later use.
* No Validation is done here, simply read/convert the BCRs