linux-kernel - Re: [PATCH] perf arm64: Use local headers for target compiler

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Message-ID: <20190321171610.wv6gcdc7jd54mato@holly.lan>
Date:   Thu, 21 Mar 2019 17:16:10 +0000
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Kim Phillips <kim.phillips@....com>,
        linux-kernel@...r.kernel.org, patches@...aro.org
Subject: Re: [PATCH] perf arm64: Use local headers for target compiler

On Thu, Mar 21, 2019 at 01:39:17PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Thu, Mar 21, 2019 at 04:13:53PM +0000, Daniel Thompson escreveu:
> > Currently the set of available syscalls is generated from the
> > target compilers default <asm-generic/unistd.h>
> > (i.e. /usr/include/asm-generic/unistd.h on a self-hosted system).
> 
> It shouldn't, Kim?

Adding a bit more detail... if I take that last line from mksyscalltbl
and run it without -dM we get the following:

ash$ gcc -E -x c $KDIR/tools/arch/arm64/include/uapi/asm/unistd.h | grep '^#'
# 1 "../arch/arm64/include/uapi/asm/unistd.h"
# 1 "<built-in>"
# 1 "<command-line>"
# 31 "<command-line>"
# 1 "/usr/include/stdc-predef.h" 1 3 4
# 32 "<command-line>" 2
# 1 "../arch/arm64/include/uapi/asm/unistd.h"
# 21 "../arch/arm64/include/uapi/asm/unistd.h"
# 1 "/usr/include/asm-generic/unistd.h" 1 3 4
# 1 "/usr/include/asm/bitsperlong.h" 1 3 4
# 22 "/usr/include/asm/bitsperlong.h" 3 4
# 1 "/usr/include/asm-generic/bitsperlong.h" 1 3 4
# 23 "/usr/include/asm/bitsperlong.h" 2 3 4
# 3 "/usr/include/asm-generic/unistd.h" 2 3 4
# 34 "/usr/include/asm-generic/unistd.h" 3 4
# 502 "/usr/include/asm-generic/unistd.h" 3 4
# 707 "/usr/include/asm-generic/unistd.h" 3 4
# 828 "/usr/include/asm-generic/unistd.h" 3 4
# 21 "../arch/arm64/include/uapi/asm/unistd.h" 2

With the extra -I we pick up the included file from the $KDIR/tools
instead.


Daniel.

> 
> > The numeric values are then generated by the host compiler using
> > tools/include/uapi/asm/unistd.h .
> > 
> > This leads to some nasty version skew problems (including failed perf
> > builds if you are running a bleeding edge distro and want to build an
> > older version of perf for testing).
> > 
> > Let's make the target compiler use the local headers too.
> > 
> > Signed-off-by: Daniel Thompson <daniel.thompson@...aro.org>
> > ---
> >  tools/perf/arch/arm64/entry/syscalls/mksyscalltbl | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/tools/perf/arch/arm64/entry/syscalls/mksyscalltbl b/tools/perf/arch/arm64/entry/syscalls/mksyscalltbl
> > index c88fd32563eb..1aca6a839e4f 100755
> > --- a/tools/perf/arch/arm64/entry/syscalls/mksyscalltbl
> > +++ b/tools/perf/arch/arm64/entry/syscalls/mksyscalltbl
> > @@ -56,7 +56,7 @@ create_table()
> >  	echo "};"
> >  }
> > 
> > -$gcc -E -dM -x c  $input	       \
> > -	|sed -ne 's/^#define __NR_//p' \
> > -	|sort -t' ' -k2 -nu	       \
> > +$gcc -I $incpath/include/uapi -E -dM -x c  $input \
> > +	|sed -ne 's/^#define __NR_//p'		  \
> > +	|sort -t' ' -k2 -nu			  \
> >  	|create_table
> > --
> > 2.20.1
> 
> -- 
> 
> - Arnaldo