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From:   Daniel Axtens <dja@axtens.net>
To:     Masahiro Yamada <yamada.masahiro@socionext.com>,
        Nicholas Piggin <npiggin@gmail.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: powerpc asm-prototypes.h seems odd
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References: <CAK7LNATg7O0ZQQ4fe2maNqf0ascHU8b2Mfnqkrxzpzj8D_X7pQ@mail.gmail.com>
Date:   Wed, 28 Aug 2019 00:04:38 +1000
Message-ID: <871rx64scp.fsf@dja-thinkpad.axtens.net>
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Masahiro Yamada <yamada.masahiro@socionext.com> writes:

> Hi.
>
> Lots of powerpc files include <asm/asm-prototypes.h>,
> and powerpc is the only architecture that does this.
>
> <asm/asm-prototypes.h> exists to support modversion for asm.
> So, it is supposed to be parsed by genksysms, not to be
> included from other files.  Right?

It exists to support sparse, squashing a bunch of sparse warnings.

From the commit where I introduced it:

commit 42f5b4cacd783faf05e3ff8bf85e8be31f3dfa9d
Author: Daniel Axtens <dja@axtens.net>
Date:   Wed May 18 11:16:50 2016 +1000

    powerpc: Introduce asm-prototypes.h
    
    Sparse picked up a number of functions that are implemented in C and
    then only referred to in asm code.
    
    This introduces asm-prototypes.h, which provides a place for
    prototypes of these functions.
    
    This silences some sparse warnings.
    
    Signed-off-by: Daniel Axtens <dja@axtens.net>
    [mpe: Add include guards, clean up copyright & GPL text]
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Regards,
Daniel

>
>
> $  git grep  asm/asm-prototypes.h
> arch/arm64/include/asm/asm-prototypes.h: * ... kbuild will
> automatically pick these up from <asm/asm-prototypes.h> and
> arch/powerpc/kernel/early_32.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/irq.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/machine_kexec_64.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/process.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/prom_init.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/ptrace.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/security.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/setup_32.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/signal_32.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/signal_64.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/smp.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/syscalls.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/tau_6xx.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/time.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/trace/ftrace.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kernel/traps.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kvm/book3s_emulate.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kvm/book3s_hv.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kvm/book3s_hv_builtin.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kvm/book3s_hv_rm_xive.c:#include <asm/asm-prototypes.h>
> arch/powerpc/kvm/book3s_pr.c:#include <asm/asm-prototypes.h>
> arch/powerpc/lib/vmx-helper.c:#include <asm/asm-prototypes.h>
> arch/powerpc/mm/book3s64/hash_utils.c:#include <asm/asm-prototypes.h>
> arch/powerpc/mm/book3s64/slb.c:#include <asm/asm-prototypes.h>
> arch/powerpc/platforms/powernv/idle.c:#include <asm/asm-prototypes.h>
> arch/powerpc/platforms/powernv/opal-call.c:#include <asm/asm-prototypes.h>
> arch/powerpc/platforms/powernv/opal-tracepoints.c:#include
> <asm/asm-prototypes.h>
> arch/powerpc/platforms/pseries/lpar.c:#include <asm/asm-prototypes.h>
> scripts/Makefile.build:# .S file exports must have their C prototypes
> defined in asm/asm-prototypes.h
> scripts/Makefile.build:     echo "\#include <asm/asm-prototypes.h>" ;
>                             \
> scripts/Makefile.build:ASM_PROTOTYPES := $(wildcard
> $(srctree)/arch/$(SRCARCH)/include/asm/asm-prototypes.h)
>
>
>
> -- 
> Best Regards
> Masahiro Yamada