Re: [PATCH 10/7] riscv: Implement the new page table range API

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Hi Matthew,

On 2/15/23 01:04, Matthew Wilcox (Oracle) wrote:
Add set_ptes(), update_mmu_cache_range() and flush_dcache_folio().

The PG_dcache_clear flag changes from being a per-page bit to being a
per-folio bit.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
  arch/riscv/include/asm/cacheflush.h | 19 +++++++++----------
  arch/riscv/include/asm/pgtable.h    | 25 ++++++++++++++++++-------
  arch/riscv/mm/cacheflush.c          | 11 ++---------
  3 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/arch/riscv/include/asm/cacheflush.h b/arch/riscv/include/asm/cacheflush.h
index 03e3b95ae6da..10e5e96f09b5 100644
--- a/arch/riscv/include/asm/cacheflush.h
+++ b/arch/riscv/include/asm/cacheflush.h
@@ -15,20 +15,19 @@ static inline void local_flush_icache_all(void)
#define PG_dcache_clean PG_arch_1 -static inline void flush_dcache_page(struct page *page)
+static inline void flush_dcache_folio(struct folio *folio)
  {
-	/*
-	 * HugeTLB pages are always fully mapped and only head page will be
-	 * set PG_dcache_clean (see comments in flush_icache_pte()).
-	 */
-	if (PageHuge(page))
-		page = compound_head(page);
-
-	if (test_bit(PG_dcache_clean, &page->flags))
-		clear_bit(PG_dcache_clean, &page->flags);
+	if (test_bit(PG_dcache_clean, &folio->flags))
+		clear_bit(PG_dcache_clean, &folio->flags);
  }
+#define flush_dcache_folio flush_dcache_folio
  #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1
+static inline void flush_dcache_page(struct page *page)
+{
+	flush_dcache_folio(page_folio(page));
+}
+
  /*
   * RISC-V doesn't have an instruction to flush parts of the instruction cache,
   * so instead we just flush the whole thing.
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 13222fd5c4b4..03706c833e70 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -405,8 +405,8 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
/* Commit new configuration to MMU hardware */
-static inline void update_mmu_cache(struct vm_area_struct *vma,
-	unsigned long address, pte_t *ptep)
+static inline void update_mmu_cache_range(struct vm_area_struct *vma,
+		unsigned long address, pte_t *ptep, unsigned int nr)
  {
  	/*
  	 * The kernel assumes that TLBs don't cache invalid entries, but
@@ -415,8 +415,10 @@ static inline void update_mmu_cache(struct vm_area_struct *vma,
  	 * Relying on flush_tlb_fix_spurious_fault would suffice, but
  	 * the extra traps reduce performance.  So, eagerly SFENCE.VMA.
  	 */
-	flush_tlb_page(vma, address);
+	flush_tlb_range(vma, address, address + nr * PAGE_SIZE);
  }
+#define update_mmu_cache(vma, addr, ptep) \
+	update_mmu_cache_range(vma, addr, ptep, 1)
#define __HAVE_ARCH_UPDATE_MMU_TLB
  #define update_mmu_tlb update_mmu_cache
@@ -456,12 +458,21 @@ static inline void __set_pte_at(struct mm_struct *mm,
  	set_pte(ptep, pteval);
  }
-static inline void set_pte_at(struct mm_struct *mm,
-	unsigned long addr, pte_t *ptep, pte_t pteval)
+static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
+		pte_t *ptep, pte_t pteval, unsigned int nr)
  {
-	page_table_check_ptes_set(mm, addr, ptep, pteval, 1);
-	__set_pte_at(mm, addr, ptep, pteval);
+	page_table_check_ptes_set(mm, addr, ptep, pteval, nr);
+
+	for (;;) {
+		__set_pte_at(mm, addr, ptep, pteval);
+		if (--nr == 0)
+			break;
+		ptep++;
+		addr += PAGE_SIZE;
+		pte_val(pteval) += 1 << _PAGE_PFN_SHIFT;
+	}
  }
+#define set_pte_at(mm, addr, ptep, pte) set_ptes(mm, addr, ptep, pte, 1)
static inline void pte_clear(struct mm_struct *mm,
  	unsigned long addr, pte_t *ptep)
diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
index 3cc07ed45aeb..b725c3f6f57f 100644
--- a/arch/riscv/mm/cacheflush.c
+++ b/arch/riscv/mm/cacheflush.c
@@ -81,16 +81,9 @@ void flush_icache_mm(struct mm_struct *mm, bool local)
  #ifdef CONFIG_MMU
  void flush_icache_pte(pte_t pte)
  {
-	struct page *page = pte_page(pte);
+	struct folio *folio = page_folio(pte_page(pte));
- /*
-	 * HugeTLB pages are always fully mapped, so only setting head page's
-	 * PG_dcache_clean flag is enough.
-	 */
-	if (PageHuge(page))
-		page = compound_head(page);
-
-	if (!test_and_set_bit(PG_dcache_clean, &page->flags))
+	if (!test_and_set_bit(PG_dcache_clean, &folio->flags))
  		flush_icache_all();
  }
  #endif /* CONFIG_MMU */

Reviewed-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>

Thanks,

Alex





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