[PATCH v12 4/5] arm64: Implement page table free interfaces
From: Will Deacon <hidden>
Date: 2018-06-04 12:12:59
Also in:
lkml
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 tablesPlease can you rewrite this describing the problem that you're solving, rather than a brief summary of some requirements?
quoted hunk ↗ jump to hunk
Signed-off-by: Chintan Pandya <redacted> --- 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.
+ table = pud_page_vaddr(pud); + entry = table;
Could you rename entry -> pmdp, please?
+ 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. Will