Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <CAKwvOdku_BOi6m2ugaef6=8+VH_+KAHH-Ch+uZZqMr8WAKARCw@mail.gmail.com>
In-Reply-To: <CAKwvOdku_BOi6m2ugaef6=8+VH_+KAHH-Ch+uZZqMr8WAKARCw@mail.gmail.com>
From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Tue, 31 Jul 2018 16:09:06 -0700
Message-ID: <CAKwvOdn1Ri2VP9hNfKwQ3WMzL278e7-3DGusZc1cwQZbk9H6nw@mail.gmail.com>
Subject: Re: Getting the instruction pointer on a per arch basis
To:     schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com,
        ysato@users.sourceforge.jp, dalias@libc.org, tony.luck@intel.com,
        fenghua.yu@intel.com, msalter@redhat.com,
        jacquiot.aurelien@gmail.com,
        "David S. Miller" <davem@davemloft.net>,
        Thomas Gleixner <tglx@linutronix.de>, mingo@redhat.com
Cc:     Pirama Arumuga Nainar <pirama@google.com>,
        Greg Hackmann <ghackmann@google.com>,
        Mark Salyzyn <salyzyn@google.com>,
        LKML <linux-kernel@vger.kernel.org>, linux-s390@vger.kernel.org,
        linux-sh@vger.kernel.org, linux-ia64@vger.kernel.org,
        linux-c6x-dev@linux-c6x.org, sparclinux@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

+ More maintainers and lists for visibility

On Tue, Jul 31, 2018 at 3:32 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> I'm currently looking into cleaning up the code duplication between
> current_text_addr() and _THIS_IP_, virtually every implementation of
> current_text_addr() and _THIS_IP_ itself are basically:
>
> #define _THIS_IP_ ({ __label__ _l; _l: &&_l; })
>
> For a few arch's, they have inline assembly instead (for
> current_text_addr()).  Examples:
> * s390
> * sh
> * ia64
> * x86 (um and 32b)
> * c6x
> * sparc
>
> I have a patch that cuts down on the duplication, but I don't
> understand why the few arch specific implementations are necessary.  I
> could reduce the duplication further if it's ok to just use the
> statement expression.
>
> Does anyone know why this is the case?
> --
> Thanks,
> ~Nick Desaulniers