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From: Mark Brown <broonie@kernel.org>
Date: Sat, 03 Feb 2024 12:25:27 +0000
Subject: [PATCH v8 01/38] arm64/mm: Restructure arch_validate_flags() for
 extensibility
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Message-Id: <20240203-arm64-gcs-v8-1-c9fec77673ef@kernel.org>
References: <20240203-arm64-gcs-v8-0-c9fec77673ef@kernel.org>
In-Reply-To: <20240203-arm64-gcs-v8-0-c9fec77673ef@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>, 
 Will Deacon <will@kernel.org>, Jonathan Corbet <corbet@lwn.net>, 
 Andrew Morton <akpm@linux-foundation.org>, Marc Zyngier <maz@kernel.org>, 
 Oliver Upton <oliver.upton@linux.dev>, James Morse <james.morse@arm.com>, 
 Suzuki K Poulose <suzuki.poulose@arm.com>, Arnd Bergmann <arnd@arndb.de>, 
 Oleg Nesterov <oleg@redhat.com>, Eric Biederman <ebiederm@xmission.com>, 
 Kees Cook <keescook@chromium.org>, Shuah Khan <shuah@kernel.org>, 
 "Rick P. Edgecombe" <rick.p.edgecombe@intel.com>, 
 Deepak Gupta <debug@rivosinc.com>, Ard Biesheuvel <ardb@kernel.org>, 
 Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Cc: "H.J. Lu" <hjl.tools@gmail.com>, 
 Paul Walmsley <paul.walmsley@sifive.com>, 
 Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>, 
 Florian Weimer <fweimer@redhat.com>, Christian Brauner <brauner@kernel.org>, 
 Thiago Jung Bauermann <thiago.bauermann@linaro.org>, 
 linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, 
 kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, 
 linux-arch@vger.kernel.org, linux-mm@kvack.org, 
 linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, 
 linux-riscv@lists.infradead.org, Mark Brown <broonie@kernel.org>

Currently arch_validate_flags() is written in a very non-extensible
fashion, returning immediately if MTE is not supported and writing the MTE
check as a direct return. Since we will want to add more checks for GCS
refactor the existing code to be more extensible, no functional change
intended.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/include/asm/mman.h | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h
index 5966ee4a6154..c21849ffdd88 100644
--- a/arch/arm64/include/asm/mman.h
+++ b/arch/arm64/include/asm/mman.h
@@ -52,11 +52,17 @@ static inline bool arch_validate_prot(unsigned long prot,
 
 static inline bool arch_validate_flags(unsigned long vm_flags)
 {
-	if (!system_supports_mte())
-		return true;
+	if (system_supports_mte()) {
+		/*
+		 * only allow VM_MTE if VM_MTE_ALLOWED has been set
+		 * previously
+		 */
+		if ((vm_flags & VM_MTE) && !(vm_flags & VM_MTE_ALLOWED))
+			return false;
+	}
+
+	return true;
 
-	/* only allow VM_MTE if VM_MTE_ALLOWED has been set previously */
-	return !(vm_flags & VM_MTE) || (vm_flags & VM_MTE_ALLOWED);
 }
 #define arch_validate_flags(vm_flags) arch_validate_flags(vm_flags)
 

-- 
2.30.2