On 5/23/2018 7:31 PM, Will Deacon wrote:
Hi Chintan,
Hi Will,
[as a side note: I'm confused on the status of this patch series, as part
of it was reposted separately by Toshi. Please can you work together?]
I will share all 4 patches once again as v10 and take latest version of
1/4 as updated by Toshi.
On Mon, Apr 30, 2018 at 01:11:33PM +0530, Chintan Pandya wrote:
Implement pud_free_pmd_page() and pmd_free_pte_page().
Implementation requires,
1) Clearing off the current pud/pmd entry
2) Invalidate TLB which could have previously
valid but not stale entry
3) Freeing of the un-used next level page tables
Signed-off-by: Chintan Pandya <cpandya@xxxxxxxxxxxxxx>
---
arch/arm64/mm/mmu.c | 29 +++++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index da98828..0f651db 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -45,6 +45,7 @@
#include <asm/memblock.h>
#include <asm/mmu_context.h>
#include <asm/ptdump.h>
+#include <asm/tlbflush.h>
#define NO_BLOCK_MAPPINGS BIT(0)
#define NO_CONT_MAPPINGS BIT(1)
@@ -973,12 +974,32 @@ int pmd_clear_huge(pmd_t *pmdp)
return 1;
}
-int pud_free_pmd_page(pud_t *pud, unsigned long addr)
+int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
{
- return pud_none(*pud);
+ pmd_t *table;
+
+ if (pmd_present(READ_ONCE(*pmdp))) {
Might also be worth checking pmd_table here, just in case. (same for pud)
I had that check in v2 as below.
if (pud_val(*pud) && !pud_huge(*pud))
But removed that in v3 as unmap should change this to NONE if it is
not table. I still don't see the need of it.
+ table = __va(pmd_val(*pmdp));
Can you avoid dereferencing *pmdp twice, and instead READ_ONCE into a local
variable, please? (same for pud)
Okay.
+ pmd_clear(pmdp);
+ __flush_tlb_kernel_pgtable(addr);
+ free_page((unsigned long) table);
Shouldn't this be pte_free_kernel, to pair with pte_alloc_kernel which
was used to allocate the page in the first place? (similarly for pud)
Okay.
+ }
+ return 1;
}
-int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
+int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
{
- return pmd_none(*pmd);
+ pmd_t *table;
+ int i;
+
+ if (pud_present(READ_ONCE(*pudp))) {
+ table = __va(pud_val(*pudp));
+ for (i = 0; i < PTRS_PER_PMD; i++)
+ pmd_free_pte_page(&table[i], addr + (i * PMD_SIZE));
I think it would be cleaner to write this as a do { ... } while, for
consistency with the ioremap and vmalloc code.
Okay.
I'll raise v10 fixing above things. Thanks for the review.
Will
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Chintan
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