linux-kernel - [PATCH v3 2/4] x86/clear_page: add clear

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Message-Id: <20250414034607.762653-3-ankur.a.arora@oracle.com>
Date: Sun, 13 Apr 2025 20:46:05 -0700
From: Ankur Arora <ankur.a.arora@...cle.com>
To: linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org
Cc: torvalds@...ux-foundation.org, akpm@...ux-foundation.org, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com, mingo@...hat.com,
        luto@...nel.org, peterz@...radead.org, paulmck@...nel.org,
        rostedt@...dmis.org, tglx@...utronix.de, willy@...radead.org,
        jon.grimm@....com, bharata@....com, raghavendra.kt@....com,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
        ankur.a.arora@...cle.com
Subject: [PATCH v3 2/4] x86/clear_page: add clear_pages()

Expose multi-page clearing via clear_pages().

Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
---
 arch/x86/include/asm/page_32.h | 6 ++++++
 arch/x86/include/asm/page_64.h | 9 +++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/page_32.h b/arch/x86/include/asm/page_32.h
index 0c623706cb7e..73c94c9e4eee 100644
--- a/arch/x86/include/asm/page_32.h
+++ b/arch/x86/include/asm/page_32.h
@@ -22,6 +22,12 @@ static inline void clear_page(void *page)
 	memset(page, 0, PAGE_SIZE);
 }
 
+static inline void clear_pages(void *page, unsigned int nsubpages)
+{
+	for (int i = 0; i < nsubpages; i++)
+		clear_page(page + i * PAGE_SIZE);
+}
+
 static inline void copy_page(void *to, void *from)
 {
 	memcpy(to, from, PAGE_SIZE);
diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h
index 45db74db9021..6781cdee6541 100644
--- a/arch/x86/include/asm/page_64.h
+++ b/arch/x86/include/asm/page_64.h
@@ -44,9 +44,9 @@ void clear_pages_orig(void *page, unsigned int length);
 void clear_pages_rep(void *page, unsigned int length);
 void clear_pages_erms(void *page, unsigned int length);
 
-static inline void clear_page(void *page)
+static inline void clear_pages(void *page, unsigned int nsubpages)
 {
-	unsigned int length = PAGE_SIZE;
+	unsigned int length = nsubpages * PAGE_SIZE;
 	/*
 	 * Clean up KMSAN metadata for the pages being cleared. The assembly call
 	 * below clobbers @page, so we perform unpoisoning before it.
@@ -61,6 +61,11 @@ static inline void clear_page(void *page)
 			   "cc", "memory", "rax", "rcx");
 }
 
+static inline void clear_page(void *page)
+{
+	clear_pages(page, 1);
+}
+
 void copy_page(void *to, void *from);
 KCFI_REFERENCE(copy_page);
 
-- 
2.31.1