linux-kernel - [PATCH v10 08/40] arm64/gcs: Provide put_user

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Message-Id: <20240801-arm64-gcs-v10-8-699e2bd2190b@kernel.org>
Date: Thu, 01 Aug 2024 13:06:35 +0100
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>, Jonathan Corbet <corbet@....net>, 
 Andrew Morton <akpm@...ux-foundation.org>, Marc Zyngier <maz@...nel.org>, 
 Oliver Upton <oliver.upton@...ux.dev>, James Morse <james.morse@....com>, 
 Suzuki K Poulose <suzuki.poulose@....com>, Arnd Bergmann <arnd@...db.de>, 
 Oleg Nesterov <oleg@...hat.com>, Eric Biederman <ebiederm@...ssion.com>, 
 Shuah Khan <shuah@...nel.org>, 
 "Rick P. Edgecombe" <rick.p.edgecombe@...el.com>, 
 Deepak Gupta <debug@...osinc.com>, Ard Biesheuvel <ardb@...nel.org>, 
 Szabolcs Nagy <Szabolcs.Nagy@....com>, Kees Cook <kees@...nel.org>
Cc: "H.J. Lu" <hjl.tools@...il.com>, 
 Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
 Florian Weimer <fweimer@...hat.com>, Christian Brauner <brauner@...nel.org>, 
 Thiago Jung Bauermann <thiago.bauermann@...aro.org>, 
 Ross Burton <ross.burton@....com>, linux-arm-kernel@...ts.infradead.org, 
 linux-doc@...r.kernel.org, kvmarm@...ts.linux.dev, 
 linux-fsdevel@...r.kernel.org, linux-arch@...r.kernel.org, 
 linux-mm@...ck.org, linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org, 
 Mark Brown <broonie@...nel.org>
Subject: [PATCH v10 08/40] arm64/gcs: Provide put_user_gcs()

In order for EL1 to write to an EL0 GCS it must use the GCSSTTR instruction
rather than a normal STTR. Provide a put_user_gcs() which does this.

Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@...aro.org>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 arch/arm64/include/asm/uaccess.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 6aba10e38d1c..ecdd47cf1d01 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -522,6 +522,24 @@ static inline int gcssttr(unsigned long __user *addr, unsigned long val)
 	return err;
 }

+static inline void put_user_gcs(unsigned long val, unsigned long __user *addr,
+				int *err)
+{
+	int ret;
+
+	if (!access_ok((char __user *)addr, sizeof(u64))) {
+		*err = -EFAULT;
+		return;
+	}
+
+	uaccess_ttbr0_enable();
+	ret = gcssttr(addr, val);
+	if (ret != 0)
+		*err = ret;
+	uaccess_ttbr0_disable();
+}
+
+
 #endif /* CONFIG_ARM64_GCS */

 #endif /* __ASM_UACCESS_H */

-- 
2.39.2