Re: [PATCH RFC bpf-next 2/3] selftests/bpf: Add uretprobe syscall test

[Jiri Olsa <olsajiri@gmail.com>]

On Mon, Mar 18, 2024 at 06:16:09PM -0700, Andrii Nakryiko wrote:
> On Mon, Mar 18, 2024 at 2:32 AM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > Add uretprobe syscall test and compare register values before
> > and after the uretprobe is hit. Also compare the register values
> > seen from attached bpf program.
> >
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> >  tools/testing/selftests/bpf/Makefile          | 13 ++-
> >  .../bpf/prog_tests/arch/x86/uprobe_syscall.S  | 89 +++++++++++++++++++
> >  .../selftests/bpf/prog_tests/uprobe_syscall.c | 84 +++++++++++++++++
> >  .../selftests/bpf/progs/uprobe_syscall.c      | 15 ++++
> >  4 files changed, 200 insertions(+), 1 deletion(-)
> >  create mode 100644 tools/testing/selftests/bpf/prog_tests/arch/x86/uprobe_syscall.S
> >  create mode 100644 tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
> >  create mode 100644 tools/testing/selftests/bpf/progs/uprobe_syscall.c
> >
> 
> Can all the above be achieved with inline assembly inside .c files? It
> would probably simplify logistics overall. We can guard with
> arch-specific #ifdefs, of course.

ok, probably yes.. I'll check

> 
> [...]
> 
> > diff --git a/tools/testing/selftests/bpf/progs/uprobe_syscall.c b/tools/testing/selftests/bpf/progs/uprobe_syscall.c
> > new file mode 100644
> > index 000000000000..0cc7e8761410
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/uprobe_syscall.c
> > @@ -0,0 +1,15 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#include "vmlinux.h"
> > +#include <bpf/bpf_helpers.h>
> > +#include <string.h>
> > +
> > +struct pt_regs regs;
> > +
> > +char _license[] SEC("license") = "GPL";
> > +
> > +SEC("uretprobe//proc/self/exe:uprobe_syscall_arch_test")
> > +int uretprobe(struct pt_regs *ctx)
> > +{
> > +       memcpy(&regs, ctx, sizeof(regs));
> 
> nit: please use __builtin_memcpy(), given this is BPF code. And we
> don't need string.h include.

right, thanks

jirka

> 
> > +       return 0;
> > +}
> > --
> > 2.44.0
> >