From: Will Deacon will@kernel.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@arm.com Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/Kconfig | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 3adcec05b1f67..27405ac94228b 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