linux-kernel - [PATCH AUTOSEL 5.2 134/185] arm64: lse: Make ARM64_LSE_ATOMICS depend on JUMP

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Message-Id: <20190922184924.32534-134-sashal@kernel.org>
Date:   Sun, 22 Sep 2019 14:48:32 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Will Deacon <will@...nel.org>,
        Andrew Murray <andrew.murray@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 5.2 134/185] arm64: lse: Make ARM64_LSE_ATOMICS depend on JUMP_LABEL

From: Will Deacon <will@...nel.org>

[ Upstream commit b32baf91f60fb9c7010bff87e68132f2ce31d9a8 ]

Support for LSE atomic instructions (CONFIG_ARM64_LSE_ATOMICS) relies on
a static key to select between the legacy LL/SC implementation which is
available on all arm64 CPUs and the super-duper LSE implementation which
is available on CPUs implementing v8.1 and later.

Unfortunately, when building a kernel with CONFIG_JUMP_LABEL disabled
(e.g. because the toolchain doesn't support 'asm goto'), the static key
inside the atomics code tries to use atomics itself. This results in a
mess of circular includes and a build failure:

In file included from ./arch/arm64/include/asm/lse.h:11,
                 from ./arch/arm64/include/asm/atomic.h:16,
                 from ./include/linux/atomic.h:7,
                 from ./include/asm-generic/bitops/atomic.h:5,
                 from ./arch/arm64/include/asm/bitops.h:26,
                 from ./include/linux/bitops.h:19,
                 from ./include/linux/kernel.h:12,
                 from ./include/asm-generic/bug.h:18,
                 from ./arch/arm64/include/asm/bug.h:26,
                 from ./include/linux/bug.h:5,
                 from ./include/linux/page-flags.h:10,
                 from kernel/bounds.c:10:
./include/linux/jump_label.h: In function ‘static_key_count’:
./include/linux/jump_label.h:254:9: error: implicit declaration of function ‘atomic_read’ [-Werror=implicit-function-declaration]
  return atomic_read(&key->enabled);
         ^~~~~~~~~~~

[ ... more of the same ... ]

Since LSE atomic instructions are not critical to the operation of the
kernel, make them depend on JUMP_LABEL at compile time.

Reviewed-by: Andrew Murray <andrew.murray@....com>
Signed-off-by: Will Deacon <will@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index cf5f1dafcf74b..885603e5df135 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1261,6 +1261,7 @@ config ARM64_PAN
 
 config ARM64_LSE_ATOMICS
 	bool "Atomic instructions"
+	depends on JUMP_LABEL
 	default y
 	help
 	  As part of the Large System Extensions, ARMv8.1 introduces new
-- 
2.20.1