Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
From:   Arnd Bergmann <arnd@kernel.org>
To:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        James Morse <james.morse@arm.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev
Subject: [PATCH] arm64: fix clang warning about TRAMP_VALIAS
Date:   Wed, 16 Mar 2022 19:38:18 +0100
Message-Id: <20220316183833.1563139-1-arnd@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Arnd Bergmann <arnd@arndb.de>

The newly introduced TRAMP_VALIAS definition causes a build warning
with clang-14:

arch/arm64/include/asm/vectors.h:66:31: error: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Werror,-Wnull-pointer-arithmetic]
                return (char *)TRAMP_VALIAS + SZ_2K * slot;

Change the addition to something clang does not complain about.

Fixes: bd09128d16fa ("arm64: Add percpu vectors for EL1")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/arm64/include/asm/vectors.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

I see this warning on 5.17-rc8, but did not test it on linux-next,
which may already have a fix.

diff --git a/arch/arm64/include/asm/vectors.h b/arch/arm64/include/asm/vectors.h
index f64613a96d53..bc9a2145f419 100644
--- a/arch/arm64/include/asm/vectors.h
+++ b/arch/arm64/include/asm/vectors.h
@@ -56,14 +56,14 @@ enum arm64_bp_harden_el1_vectors {
 DECLARE_PER_CPU_READ_MOSTLY(const char *, this_cpu_vector);
 
 #ifndef CONFIG_UNMAP_KERNEL_AT_EL0
-#define TRAMP_VALIAS	0
+#define TRAMP_VALIAS	0ul
 #endif
 
 static inline const char *
 arm64_get_bp_hardening_vector(enum arm64_bp_harden_el1_vectors slot)
 {
 	if (arm64_kernel_unmapped_at_el0())
-		return (char *)TRAMP_VALIAS + SZ_2K * slot;
+		return (char *)(TRAMP_VALIAS + SZ_2K * slot);
 
 	WARN_ON_ONCE(slot == EL1_VECTOR_KPTI);
 
-- 
2.29.2