From: Nathan Chancellor <nathan@kernel.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"David S. Miller" <davem@davemloft.net>,
Ard Biesheuvel <ardb@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
Al Viro <viro@zeniv.linux.org.uk>,
llvm@lists.linux.dev
Subject: Re: [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell"
Date: Mon, 10 Jan 2022 13:03:46 -0700 [thread overview]
Message-ID: <YdyRIgnG6jlL0HHx@archlinux-ax161> (raw)
In-Reply-To: <Ydl6MATrfA1GA0G+@gmail.com>
On Sat, Jan 08, 2022 at 12:49:04PM +0100, Ingo Molnar wrote:
>
> * Nathan Chancellor <nathan@kernel.org> 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
>
> ?
Correct.
> 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.
Neat trick! I added
#ifdef LINKER_SCRIPT
#warning debug
#endif
to arch/arm64/include/asm/rwonce.h and built with ThinLTO, which reveals:
$ make -skj"$(nproc)" ARCH=arm64 LLVM=1 defconfig
$ scripts/config -d LTO_NONE -e LTO_CLANG_THIN
$ make -skj"$(nproc)" ARCH=arm64 LLVM=1 olddefconfig arch/arm64/kvm/hyp/
In file included from arch/arm64/kvm/hyp/nvhe/hyp.lds.S:12:
In file included from ./arch/arm64/include/asm/memory.h:18:
In file included from ./arch/arm64/include/asm/thread_info.h:11:
In file included from ./include/linux/compiler.h:263:
./arch/arm64/include/asm/rwonce.h:9:2: warning: debug [-W#warnings]
#warning debug
^
1 warning generated.
I wonder if the compiler.h include could be broken up? I removed it
altogether just to see what would break and defconfig, defconfig +
CONFIG_LTO_CLANG_THIN=y, and allmodconfig all continue to build.
Cheers,
Nathan
next prev parent reply other threads:[~2022-01-10 20:03 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-02 21:57 [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-03 10:11 ` Greg Kroah-Hartman
2022-01-03 11:12 ` Ingo Molnar
2022-01-03 13:46 ` Greg Kroah-Hartman
2022-01-03 16:29 ` Ingo Molnar
2022-01-10 10:28 ` Peter Zijlstra
2022-01-04 14:10 ` [PATCH] per_task: Remove the PER_TASK_BYTES hard-coded constant Ingo Molnar
2022-01-04 15:14 ` Andy Shevchenko
2022-01-04 23:27 ` Ingo Molnar
2022-01-04 17:51 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Arnd Bergmann
2022-01-05 0:05 ` Ingo Molnar
2022-01-05 1:37 ` Arnd Bergmann
2022-01-05 9:37 ` Andy Shevchenko
2022-01-04 14:05 ` [PATCH] per_task: Implement single template to define 'struct task_struct_per_task' fields and offsets Ingo Molnar
2022-01-03 13:54 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Kirill A. Shutemov
2022-01-04 10:54 ` Ingo Molnar
2022-01-04 13:34 ` Greg Kroah-Hartman
2022-01-04 13:54 ` [PATCH] headers/uninline: Uninline single-use function: kobject_has_children() Ingo Molnar
2022-01-04 15:09 ` Greg Kroah-Hartman
2022-01-04 15:14 ` Greg Kroah-Hartman
2022-01-05 0:11 ` Ingo Molnar
2022-01-05 15:23 ` Greg Kroah-Hartman
2022-01-06 11:26 ` Ingo Molnar
2022-01-03 17:54 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Nathan Chancellor
2022-01-04 10:47 ` Ingo Molnar
2022-01-04 10:56 ` [DEBUG PATCH] DO NOT MERGE: Enable SHADOW_CALL_STACK on GCC builds, for build testing Ingo Molnar
2022-01-04 11:02 ` [PATCH] headers/deps: dcache: Move the ____cacheline_aligned attribute to the head of the definition Ingo Molnar
2022-01-04 15:05 ` kernel test robot
2022-01-04 17:51 ` Nathan Chancellor
2022-01-05 0:20 ` Ingo Molnar
2022-01-05 0:26 ` [PATCH] headers/deps: Attribute placement fixes for Clang & GCC Ingo Molnar
2022-01-04 11:19 ` [TREE] "Fast Kernel Headers" Tree WIP/development branch Ingo Molnar
2022-01-04 17:25 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Nick Desaulniers
2022-01-05 0:43 ` Ingo Molnar
2022-01-04 17:50 ` Nathan Chancellor
2022-01-05 0:35 ` [PATCH] x86/kbuild: Enable CONFIG_KALLSYMS_ALL=y in the defconfigs Ingo Molnar
2022-01-08 21:57 ` [tip: x86/build] " tip-bot2 for Ingo Molnar
2022-01-05 0:40 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-05 1:07 ` Ingo Molnar
2022-01-05 5:20 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel'\''s "Dependency Hell Paul Zimmerman
2022-01-05 21:42 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Nathan Chancellor
2022-01-08 10:32 ` [PATCH] headers/deps: Add header dependencies to .c files: <linux/ptrace_api.h> Ingo Molnar
2022-01-08 11:08 ` [PATCH] FIX: headers/deps: uapi/headers: Create usr/include/uapi symbolic link Ingo Molnar
2022-01-08 11:18 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-08 11:38 ` [PATCH] x86/bitops: Remove unused __sw_hweight64() assembly implementation Ingo Molnar
2022-01-08 11:49 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-08 12:17 ` Ingo Molnar
2022-01-10 20:03 ` Nathan Chancellor [this message]
2022-01-10 20:05 ` Nathan Chancellor
2022-01-05 22:33 ` Nathan Chancellor
2022-01-08 15:16 ` Ingo Molnar
2022-01-07 0:29 ` Nathan Chancellor
2022-01-08 11:54 ` Ingo Molnar
2022-01-04 12:36 ` Willy Tarreau
2022-01-04 16:05 ` Andy Shevchenko
2022-01-04 16:18 ` Andy Shevchenko
2022-01-15 0:42 ` Paul E. McKenney
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