[to-be-updated] arm64-add-support-for-sub-page-faults-user-probing.patch removed from -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: arm64: add support for sub-page faults user probing
has been removed from the -mm tree.  Its filename was
     arm64-add-support-for-sub-page-faults-user-probing.patch

This patch was dropped because an updated version will be merged

------------------------------------------------------
From: Catalin Marinas <catalin.marinas@arm.com>
Subject: arm64: add support for sub-page faults user probing

With MTE, even if the pte allows an access, a mismatched tag somewhere
within a page can still cause a fault.  Select ARCH_HAS_SUBPAGE_FAULTS if
MTE is enabled and implement probe_user_writeable().

Link: https://lkml.kernel.org/r/20211124192024.2408218-3-catalin.marinas@arm.com
Fixes: a48b73eca4ce ("btrfs: fix potential deadlock in the search ioctl") 
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/arm64/Kconfig               |    1 
 arch/arm64/include/asm/uaccess.h |   33 +++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

--- a/arch/arm64/include/asm/uaccess.h~arm64-add-support-for-sub-page-faults-user-probing
+++ a/arch/arm64/include/asm/uaccess.h
@@ -479,4 +479,37 @@ static inline int __copy_from_user_flush
 }
 #endif
 
+#ifdef CONFIG_ARCH_HAS_SUBPAGE_FAULTS
+static inline size_t __mte_probe_user_range(const char __user *uaddr,
+					    size_t size)
+{
+	const char __user *end = uaddr + size;
+	int err = 0;
+	char val;
+
+	uaddr = PTR_ALIGN_DOWN(uaddr, MTE_GRANULE_SIZE);
+	while (uaddr < end) {
+		/*
+		 * A read is sufficient for MTE, the caller should have probed
+		 * for the pte write permission.
+		 */
+		__raw_get_user(val, uaddr, err);
+		if (err)
+			return end - uaddr;
+		uaddr += MTE_GRANULE_SIZE;
+	}
+	(void)val;
+
+	return 0;
+}
+
+static inline size_t probe_user_writable(const void __user *uaddr,
+					 size_t size)
+{
+	if (!system_supports_mte())
+		return 0;
+	return __mte_probe_user_range(uaddr, size);
+}
+#endif /* CONFIG_ARCH_HAS_SUBPAGE_FAULTS */
+
 #endif /* __ASM_UACCESS_H */
--- a/arch/arm64/Kconfig~arm64-add-support-for-sub-page-faults-user-probing
+++ a/arch/arm64/Kconfig
@@ -1777,6 +1777,7 @@ config ARM64_MTE
 	depends on AS_HAS_LSE_ATOMICS
 	# Required for tag checking in the uaccess routines
 	depends on ARM64_PAN
+	select ARCH_HAS_SUBPAGE_FAULTS
 	select ARCH_USES_HIGH_VMA_FLAGS
 	help
 	  Memory Tagging (part of the ARMv8.5 Extensions) provides
_

Patches currently in -mm which might be from catalin.marinas@arm.com are

btrfs-avoid-live-lock-in-search_ioctl-on-hardware-with-sub-page-faults.patch