linux-kernel - [PATCH 09/15] x86: Physical address comparison in current

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Message-ID: <fde443d0e67f76a51e7ab4e96647705840f53ddb.1738686764.git.maciej.wieczor-retman@intel.com>
Date: Tue,  4 Feb 2025 18:33:50 +0100
From: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
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Subject: [PATCH 09/15] x86: Physical address comparison in current_mm pgd check

With KASAN software tag-based mode enabled PGD pointer stored in
current_mm structure is tagged while the same pointer computed through
__va(read_cr3_pa()) ends up with the tag space filled with ones.

Use current_mm->pgd' physical address and drop the __va() so the
VM_WARN_ON_ONCE can work properly and not report false positives while
KASAN is enabled.

Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
---
 arch/x86/mm/tlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 86593d1b787d..95e3dc1fb766 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -1295,7 +1295,7 @@ bool nmi_uaccess_okay(void)
 	if (loaded_mm != current_mm)
 		return false;
 
-	VM_WARN_ON_ONCE(current_mm->pgd != __va(read_cr3_pa()));
+	VM_WARN_ON_ONCE(__pa(current_mm->pgd) != read_cr3_pa());
 
 	return true;
 }
-- 
2.47.1