netdev - [PATCH v4 bpf-next 0/4] selftests/bpf: fix compiling loop{1,2,3}.c on s390

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Date:   Thu, 11 Jul 2019 16:29:26 +0200
From:   Ilya Leoshkevich <iii@...ux.ibm.com>
To:     bpf@...r.kernel.org, netdev@...r.kernel.org
Cc:     ys114321@...il.com, daniel@...earbox.net, sdf@...ichev.me,
        davem@...emloft.net, ast@...nel.org,
        Ilya Leoshkevich <iii@...ux.ibm.com>
Subject: [PATCH v4 bpf-next 0/4] selftests/bpf: fix compiling loop{1,2,3}.c on s390

Use PT_REGS_RC(ctx) instead of ctx->rax, which is not present on s390.

This patch series consists of three preparatory commits, which make it
possible to use PT_REGS_RC in BPF selftests, followed by the actual fix.

> > Will this also work for 32-bit x86?
> Thanks, this is a good catch: this builds, but makes 64-bit accesses, as
> if it used the 64-bit variant of pt_regs. I will fix this.
I found four problems in this area:

1. Selftest tracing progs are built with -target bpf, leading to struct
   pt_regs and friends being interpreted incorrectly.
2. When the Makefile is adjusted to build them without -target bpf, it
   still lacks -m32/-m64, leading to a similar issue.
3. There is no __i386__ define, leading to incorrect userspace struct
   pt_regs variant being chosen for x86.
4. Finally, there is an issue in my patch: when 1-3 are fixed, it fails
   to build, since i386 defines yet another set of field names.

I will send fixes for problems 1-3 separately, I believe for this patch
series to be correct, it's enough to fix #4 (which I did by adding
another #ifdef).

I've also changed ARCH to SRCARCH in patch #1, since while ARCH can be
e.g. "i386", SRCARCH always corresponds to directory names under arch/.

v1->v2: Split into multiple patches.
v2->v3: Added arm64 support.
v3->v4: Added i386 support, use SRCARCH instead of ARCH.

Signed-off-by: Ilya Leoshkevich <iii@...ux.ibm.com>