| Message ID | 20190829154834.26547-9-will@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: avoid out-of-line ll/sc atomics | expand |
On Thu, Aug 29, 2019 at 04:48:32PM +0100, Will Deacon wrote: > 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> > --- Reviewed-by: Andrew Murray <andrew.murray@arm.com> > 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 >
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
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(+)