linux-kernel - Re: [PATCH 5.4-rc1 BUILD FIX] s390: mark __cpacf_query() as __always

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Date:   Wed, 2 Oct 2019 08:44:20 +0200
From:   Christian Borntraeger <borntraeger@...ibm.com>
To:     Jiri Kosina <jikos@...nel.org>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-s390@...r.kernel.org, Michal Kubecek <mkubecek@...e.cz>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5.4-rc1 BUILD FIX] s390: mark __cpacf_query() as
 __always_inline


On 01.10.19 22:08, Jiri Kosina wrote:
> arch/s390/kvm/kvm-s390.c calls on several places __cpacf_query() directly, 
> which makes it impossible to meet the "i" constraint for the asm operands 
> (opcode in this case).
> 
> As we are now force-enabling CONFIG_OPTIMIZE_INLINING on all 
> architectures, this causes a build failure on s390:
> 
>    In file included from arch/s390/kvm/kvm-s390.c:44:
>    ./arch/s390/include/asm/cpacf.h: In function '__cpacf_query':
>    ./arch/s390/include/asm/cpacf.h:179:2: warning: asm operand 3 probably doesn't match constraints
>      179 |  asm volatile(
>          |  ^~~
>    ./arch/s390/include/asm/cpacf.h:179:2: error: impossible constraint in 'asm'
> 
> Mark __cpacf_query() as __always_inline in order to fix that, analogically 
> how we fixes __cpacf_check_opcode(), cpacf_query_func() and scpacf_query() 
> already.
> 
> Reported-and-tested-by: Michal Kubecek <mkubecek@...e.cz>
> Fixes: d83623c5eab2 ("s390: mark __cpacf_check_opcode() and cpacf_query_func() as __always_inline")
> Fixes: e60fb8bf68d4 ("s390/cpacf: mark scpacf_query() as __always_inline")
> Fixes: ac7c3e4ff401 ("compiler: enable CONFIG_OPTIMIZE_INLINING forcibly")
> Fixes: 9012d011660e ("compiler: allow all arches to enable CONFIG_OPTIMIZE_INLINING")
> Signed-off-by: Jiri Kosina <jkosina@...e.cz>

Thanks applied. 


> 
> I am wondering how is it possible that none of the build-testing 
> infrastructure we have running against linux-next caught this? Not enough 
> non-x86 coverage?

We do build-test linux-next daily. Maybe our compiler just made a different
inlining decision.