On 6/4/2018 5:43 PM, Will Deacon wrote:
On Fri, Jun 01, 2018 at 06:09:17PM +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
Please can you rewrite this describing the problem that you're solving,
rather than a brief summary of some requirements?
Okay. I'll fix this in v13.
Signed-off-by: Chintan Pandya <[email protected]>
---
arch/arm64/mm/mmu.c | 38 ++++++++++++++++++++++++++++++++++----
1 file changed, 34 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 8ae5d7a..6e7e16c 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)
@@ -977,12 +978,41 @@ 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);
+ pte_t *table;
+ pmd_t pmd;
+
+ pmd = READ_ONCE(*pmdp);
+ if (pmd_present(pmd)) {
+ table = pmd_page_vaddr(pmd);
+ pmd_clear(pmdp);
+ __flush_tlb_kernel_pgtable(addr);
+ pte_free_kernel(NULL, table);
+ }
+ 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;
+ pmd_t *entry;
+ pud_t pud;
+ unsigned long next, end;
+
+ pud = READ_ONCE(*pudp);
+ if (pud_present(pud)) {
Just some stylistic stuff, but please can you rewrite this as:
if (!pud_present(pud) || VM_WARN_ON(!pud_table(pud)))
return 1;
similarly for the pmd/pte code above.
Okay. v13 will have this.
+ table = pud_page_vaddr(pud);
+ entry = table;
Could you rename entry -> pmdp, please?
Sure.
+ next = addr;
+ end = addr + PUD_SIZE;
+ do {
+ pmd_free_pte_page(entry, next);
+ } while (entry++, next += PMD_SIZE, next != end);
+
+ pud_clear(pudp);
+ __flush_tlb_kernel_pgtable(addr);
+ pmd_free(NULL, table);
+ }
+ return 1;
So with these patches, we only ever return 1 from these helpers. It looks
like the same is true for x86, so how about we make them void and move the
calls inside the conditionals in lib/ioremap.c? Obviously, this would be a
separate patch on the end.
That sounds valid code churn to me. But since x86 discussion is not
concluded yet, I would wait to share until that gets resolved. May be
not in v13 but separate effort. Would that be okay to you ?
Will
Chintan
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