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@xxxxxxxxxxxxx>
