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 <20210927064300.624279-20-chenhuacai@loongson.cn> <f6fc1fa8bf4decf97d76900a64fe0bc2bf25576d.camel@mengyan1223.wang>
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From:   Huacai Chen <chenhuacai@gmail.com>
Date:   Sat, 2 Oct 2021 18:53:37 +0800
Message-ID: <CAAhV-H6WWPeYfYsAM2UfKH1GYVA=Ww2k1akAy-ve28u3kJL4pA@mail.gmail.com>
Subject: Re: [PATCH V4 19/22] LoongArch: Add VDSO and VSYSCALL support
To:     Xi Ruoyao <xry111@mengyan1223.wang>
Cc:     Huacai Chen <chenhuacai@loongson.cn>,
        Arnd Bergmann <arnd@arndb.de>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Airlie <airlied@linux.ie>,
        Jonathan Corbet <corbet@lwn.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Yanteng Si <siyanteng@loongson.cn>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>
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Hi, Ruoyao,

On Thu, Sep 30, 2021 at 11:43 PM Xi Ruoyao <xry111@mengyan1223.wang> wrote:
>
> On Mon, 2021-09-27 at 14:42 +0800, Huacai Chen wrote:
> > diff --git a/arch/loongarch/vdso/gen_vdso_offsets.sh
> > b/arch/loongarch/vdso/gen_vdso_offsets.sh
> > new file mode 100755
> > index 000000000000..7da255fea213
> > --- /dev/null
> > +++ b/arch/loongarch/vdso/gen_vdso_offsets.sh
> > @@ -0,0 +1,14 @@
> > +#!/bin/sh
> > +# SPDX-License-Identifier: GPL-2.0
> > +
> > +#
> > +# Derived from RISC-V and ARM64:
> > +# Author: Will Deacon <will.deacon@arm.com>
> > +#
> > +# Match symbols in the DSO that look like VDSO_*; produce a header
> > file
> > +# of constant offsets into the shared object.
> > +#
> > +
> > +LC_ALL=C
>
> I'm wondering whether this line is really useful... There is no "export"
> here so the variable won't be passed to the environment of the sed
> command below.
Have you encountered some problems with this? It just works for me,
and both ARM64 and RISCV are the same.

Huacai
>
> > +sed -n -e 's/^00*/0/' -e \
> > +'s/^\([0-9a-fA-F]*\) . VDSO_\([a-zA-Z0-9_]*\)$/\#define
> > vdso_offset_\2\t0x\1/p'