[PATCH 06/10] asm-generic: pgalloc: Provide generic p4d_{alloc_one,free}

Kevin Brodsky
2024-12-19T16:54:38Z

Four architectures currently implement 5-level pgtables: arm64,
riscv, x86 and s390. The first three have essentially the same
implementation for p4d_alloc_one() and p4d_free(), so we've got an
opportunity to reduce duplication like at the lower levels.

Provide a generic version of p4d_alloc_one() and p4d_free(), and
make use of it on those architectures.

Their implementation is the same as at PUD level, except that
p4d_free() performs a runtime check by calling mm_p4d_folded().
5-level pgtables depend on a runtime-detected hardware feature on
all supported architectures, so we might as well include this check
in the generic implementation. No runtime check is required in
p4d_alloc_one() as the top-level p4d_alloc() already does the
required check.

Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
arch/arm64/include/asm/pgalloc.h | 17 ------------
arch/riscv/include/asm/pgalloc.h | 23 ----------------
arch/x86/include/asm/pgalloc.h | 18 -------------
include/asm-generic/pgalloc.h | 45 ++++++++++++++++++++++++++++++++
4 files changed, 45 insertions(+), 58 deletions(-)

diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
index e75422864d1b..2965f5a7e39e 100644
--- a/arch/arm64/include/asm/pgalloc.h
+++ b/arch/arm64/include/asm/pgalloc.h
@@ -85,23 +85,6 @@ static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgdp, p4d_t *p4dp)
__pgd_populate(pgdp, __pa(p4dp), pgdval);
}

-static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long addr)
-{
- gfp_t gfp = GFP_PGTABLE_USER;
-
- if (mm == &init_mm)
- gfp = GFP_PGTABLE_KERNEL;
- return (p4d_t *)get_zeroed_page(gfp);
-}
-
-static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)
-{
- if (!pgtable_l5_enabled())
- return;
- BUG_ON((unsigned long)p4d & (PAGE_SIZE-1));
- free_page((unsigned long)p4d);
-}
-
#define __p4d_free_tlb(tlb, p4d, addr) p4d_free((tlb)->mm, p4d)
#else
static inline void __pgd_populate(pgd_t *pgdp, phys_addr_t p4dp, pgdval_t prot)
diff --git a/arch/riscv/include/asm/pgalloc.h b/arch/riscv/include/asm/pgalloc.h
index 8ad0bbe838a2..551d614d3369 100644
--- a/arch/riscv/include/asm/pgalloc.h
+++ b/arch/riscv/include/asm/pgalloc.h
@@ -105,29 +105,6 @@ static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
}
}

-#define p4d_alloc_one p4d_alloc_one
-static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long addr)
-{
- gfp_t gfp = GFP_PGTABLE_USER;
-
- if (mm == &init_mm)
- gfp = GFP_PGTABLE_KERNEL;
- return (p4d_t *)get_zeroed_page(gfp);
-}
-
-static inline void __p4d_free(struct mm_struct *mm, p4d_t *p4d)
-{
- BUG_ON((unsigned long)p4d & (PAGE_SIZE-1));
- free_page((unsigned long)p4d);
-}
-
-#define p4d_free p4d_free
-static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)
-{
- if (pgtable_l5_enabled)
- __p4d_free(mm, p4d);
-}
-
static inline void __p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,
unsigned long addr)
{
diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index dcd836b59beb..dd4841231bb9 100644
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -147,24 +147,6 @@ static inline void pgd_populate_safe(struct mm_struct *mm, pgd_t *pgd, p4d_t *p4
set_pgd_safe(pgd, __pgd(_PAGE_TABLE | __pa(p4d)));
}

-static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long addr)
-{
- gfp_t gfp = GFP_KERNEL_ACCOUNT;
-
- if (mm == &init_mm)
- gfp &= ~__GFP_ACCOUNT;
- return (p4d_t *)get_zeroed_page(gfp);
-}
-
-static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)
-{
- if (!pgtable_l5_enabled())
- return;
-
- BUG_ON((unsigned long)p4d & (PAGE_SIZE-1));
- free_page((unsigned long)p4d);
-}
-
extern void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d);

static inline void __p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,
diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index 7c48f5fbf8aa..59131629ac9c 100644
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -215,6 +215,51 @@ static inline void pud_free(struct mm_struct *mm, pud_t *pud)

#endif /* CONFIG_PGTABLE_LEVELS > 3 */

+#if CONFIG_PGTABLE_LEVELS > 4
+
+static inline p4d_t *__p4d_alloc_one_noprof(struct mm_struct *mm, unsigned long addr)
+{
+ gfp_t gfp = GFP_PGTABLE_USER;
+ struct ptdesc *ptdesc;
+
+ if (mm == &init_mm)
+ gfp = GFP_PGTABLE_KERNEL;
+ gfp &= ~__GFP_HIGHMEM;
+
+ ptdesc = pagetable_alloc_noprof(gfp, 0);
+ if (!ptdesc)
+ return NULL;
+
+ return ptdesc_address(ptdesc);
+}
+#define __p4d_alloc_one(...) alloc_hooks(__p4d_alloc_one_noprof(__VA_ARGS__))
+
+#ifndef __HAVE_ARCH_P4D_ALLOC_ONE
+static inline p4d_t *p4d_alloc_one_noprof(struct mm_struct *mm, unsigned long addr)
+{
+ return __p4d_alloc_one_noprof(mm, addr);
+}
+#define p4d_alloc_one(...) alloc_hooks(p4d_alloc_one_noprof(__VA_ARGS__))
+#endif
+
+static inline void __p4d_free(struct mm_struct *mm, p4d_t *p4d)
+{
+ struct ptdesc *ptdesc = virt_to_ptdesc(p4d);
+
+ BUG_ON((unsigned long)p4d & (PAGE_SIZE-1));
+ pagetable_free(ptdesc);
+}
+
+#ifndef __HAVE_ARCH_P4D_FREE
+static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)
+{
+ if (!mm_p4d_folded(mm))
+ __p4d_free(mm, p4d);
+}
+#endif
+
+#endif /* CONFIG_PGTABLE_LEVELS > 4 */
+
#ifndef __HAVE_ARCH_PGD_FREE
static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
--
2.47.0