* Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
> 5. Build error in arch/arm64/kvm/hyp/nvhe with LTO
>
> With arm64 + CONFIG_LTO_CLANG_THIN=y, I see:
>
> $ make -skj"$(nproc)" ARCH=arm64 LLVM=1 defconfig
>
> $ scripts/config -e LTO_CLANG_THIN
>
> $ make -skj"$(nproc)" ARCH=arm64 LLVM=1 olddefconfig arch/arm64/kvm/hyp/nvhe/
> ld.lld: error: arch/arm64/kvm/hyp/nvhe/hyp.lds:2: unknown directive: .macro
> >>> .macro __put, val, name
> >>> ^
> make[5]: *** [arch/arm64/kvm/hyp/nvhe/Makefile:51: arch/arm64/kvm/hyp/nvhe/kvm_nvhe.tmp.o] Error 1
>
> I was not able to figure out the exact include chain but CONFIG_LTO
> causes asm/alternative-macros.h to be included in asm/rwonce.h, which
> eventually gets included in either asm/cache.h or asm/memory.h.
>
> I managed to solve this with the following diff but I am not sure if
> there is a better or cleaner way to do that.
>
> diff --git a/arch/arm64/include/asm/rwonce.h b/arch/arm64/include/asm/rwonce.h
> index 1bce62fa908a..e19572a205d0 100644
> --- a/arch/arm64/include/asm/rwonce.h
> +++ b/arch/arm64/include/asm/rwonce.h
> @@ -5,7 +5,7 @@
> #ifndef __ASM_RWONCE_H
> #define __ASM_RWONCE_H
>
> -#ifdef CONFIG_LTO
> +#if defined(CONFIG_LTO) && !defined(LINKER_SCRIPT)
>
> #include <linux/compiler_types.h>
> #include <asm/alternative-macros.h>
> @@ -66,7 +66,7 @@
> })
>
> #endif /* !BUILD_VDSO */
> -#endif /* CONFIG_LTO */
> +#endif /* CONFIG_LTO && !LINKER_SCRIPT */
So the error message suggests that the linker script somehow ends up
including asm-generic/export.h:
kepler:~/mingo.tip.git> git grep 'macro __put'
include/asm-generic/export.h:.macro __put, val, name
?
But I'd guess that similar to the __ASSEMBLY__ patterns we have in headers,
not including the rwonce.h bits if LINKER_SCRIPT is defined is probably
close to the right solution - but it would also know how such a low level
header ended up in a linker script. Might have been to pick up some offset
or size definition somewhere?
I.e. how did the build end up including asm/rwonce.h?
You can generally debug such weird dependency chains by putting a
debug #warning into the affected header - such as the patch below.
This prints a stack of the header dependencies:
CC kernel/sched/core.o
In file included from ./include/linux/compiler.h:263,
from ./include/linux/static_call_types.h:7,
from ./include/linux/kernel.h:6,
from ./include/linux/highmem.h:5,
from kernel/sched/core.c:9:
./arch/arm64/include/asm/rwonce.h:8:2: warning: #warning debug [-Wcpp]
8 | #warning debug
... and should in principle also work in the linker script context.
Thanks,
Ingo
===============>
arch/arm64/include/asm/rwonce.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm64/include/asm/rwonce.h b/arch/arm64/include/asm/rwonce.h
index 1bce62fa908a..5b3305381481 100644
--- a/arch/arm64/include/asm/rwonce.h
+++ b/arch/arm64/include/asm/rwonce.h
@@ -5,6 +5,8 @@
#ifndef __ASM_RWONCE_H
#define __ASM_RWONCE_H
+#warning debug
+
#ifdef CONFIG_LTO
#include <linux/compiler_types.h>
