linux-kernel - [PATCH 6/7] mm/x86: Add missing pud helpers

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Date: Fri, 21 Jun 2024 10:25:03 -0400
From: Peter Xu <peterx@...hat.com>
To: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Cc: x86@...nel.org,
	Borislav Petkov <bp@...en8.de>,
	Dave Jiang <dave.jiang@...el.com>,
	"Kirill A . Shutemov" <kirill@...temov.name>,
	Ingo Molnar <mingo@...hat.com>,
	Oscar Salvador <osalvador@...e.de>,
	peterx@...hat.com,
	Matthew Wilcox <willy@...radead.org>,
	Vlastimil Babka <vbabka@...e.cz>,
	Dan Williams <dan.j.williams@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linuxppc-dev@...ts.ozlabs.org,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Rik van Riel <riel@...riel.com>,
	Mel Gorman <mgorman@...hsingularity.net>,
	"Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
	Nicholas Piggin <npiggin@...il.com>,
	Huang Ying <ying.huang@...el.com>
Subject: [PATCH 6/7] mm/x86: Add missing pud helpers

These new helpers will be needed for pud entry updates soon.  Namely:

- pudp_invalidate()
- pud_modify()

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: x86@...nel.org
Signed-off-by: Peter Xu <peterx@...hat.com>
---
 arch/x86/include/asm/pgtable.h | 36 ++++++++++++++++++++++++++++++++++
 arch/x86/mm/pgtable.c          | 11 +++++++++++
 2 files changed, 47 insertions(+)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 25fc6d809572..3c23077adca6 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -775,6 +775,12 @@ static inline pmd_t pmd_mkinvalid(pmd_t pmd)
 		      __pgprot(pmd_flags(pmd) & ~(_PAGE_PRESENT|_PAGE_PROTNONE)));
 }
 
+static inline pud_t pud_mkinvalid(pud_t pud)
+{
+	return pfn_pud(pud_pfn(pud),
+		       __pgprot(pud_flags(pud) & ~(_PAGE_PRESENT|_PAGE_PROTNONE)));
+}
+
 static inline u64 flip_protnone_guard(u64 oldval, u64 val, u64 mask);
 
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
@@ -839,6 +845,21 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
 	return pmd_result;
 }
 
+static inline pud_t pud_modify(pud_t pud, pgprot_t newprot)
+{
+	pudval_t val = pud_val(pud), oldval = val;
+
+	/*
+	 * NOTE: no need to consider shadow stack complexities because it
+	 * doesn't support 1G mappings.
+	 */
+	val &= _HPAGE_CHG_MASK;
+	val |= check_pgprot(newprot) & ~_HPAGE_CHG_MASK;
+	val = flip_protnone_guard(oldval, val, PHYSICAL_PUD_PAGE_MASK);
+
+	return __pud(val);
+}
+
 /*
  * mprotect needs to preserve PAT and encryption bits when updating
  * vm_page_prot
@@ -1377,10 +1398,25 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
 }
 #endif
 
+static inline pud_t pudp_establish(struct vm_area_struct *vma,
+		unsigned long address, pud_t *pudp, pud_t pud)
+{
+	if (IS_ENABLED(CONFIG_SMP)) {
+		return xchg(pudp, pud);
+	} else {
+		pud_t old = *pudp;
+		WRITE_ONCE(*pudp, pud);
+		return old;
+	}
+}
+
 #define __HAVE_ARCH_PMDP_INVALIDATE_AD
 extern pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma,
 				unsigned long address, pmd_t *pmdp);
 
+pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
+		      pud_t *pudp);
+
 /*
  * Page table pages are page-aligned.  The lower half of the top
  * level is used for userspace and the top half for the kernel.
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 93e54ba91fbf..4e245a1526ad 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -641,6 +641,17 @@ pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address,
 }
 #endif
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
+		     pud_t *pudp)
+{
+	VM_WARN_ON_ONCE(!pud_present(*pudp));
+	pud_t old = pudp_establish(vma, address, pudp, pud_mkinvalid(*pudp));
+	flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
+	return old;
+}
+#endif
+
 /**
  * reserve_top_address - reserves a hole in the top of kernel address space
  * @reserve - size of hole to reserve
-- 
2.45.0