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

From: Daniel Thompson
Date: Thu Mar 21 2019 - 13:16:19 EST


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@xxxxxxxxxx>
> > ---
> > 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