[PATCH v5 08/10] arm64: lse: Make ARM64_LSE_ATOMICS depend on JUMP_LABEL

From: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: mark.rutland@arm.com, peterz@infradead.org,
	catalin.marinas@arm.com, ndesaulniers@google.com,
	robin.murphy@arm.com, Ard.Biesheuvel@arm.com,
	andrew.murray@arm.com, natechancellor@gmail.com,
	Will Deacon <will@kernel.org>
Subject: [PATCH v5 08/10] arm64: lse: Make ARM64_LSE_ATOMICS depend on JUMP_LABEL
Date: Thu, 29 Aug 2019 16:48:32 +0100	[thread overview]
Message-ID: <20190829154834.26547-9-will@kernel.org> (raw)
In-Reply-To: <20190829154834.26547-1-will@kernel.org>

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.

Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 3adcec05b1f6..27405ac94228 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1263,6 +1263,7 @@ 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
-- 
2.11.0


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