On Tue, Aug 16, 2022 at 3:18 AM Jiri Olsa <olsajiri@xxxxxxxxx> wrote:
>
> On Tue, Aug 16, 2022 at 09:00:20AM +0200, Jiri Olsa wrote:
> > On Mon, Aug 15, 2022 at 08:25:51PM -0700, Andrii Nakryiko wrote:
> > > On Thu, Aug 11, 2022 at 2:16 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> > > >
> > > > With CONFIG_X86_KERNEL_IBT enabled the test for kprobe with offset
> > > > won't work because of the extra endbr instruction.
> > > >
> > > > As suggested by Andrii adding CONFIG_X86_KERNEL_IBT detection
> > > > and using appropriate offset value based on that.
> > > >
> > > > Also removing test7 program, because it does the same as test6.
> > > >
> > > > Suggested-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> > > > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> > > > ---
> > > > .../bpf/prog_tests/get_func_ip_test.c | 62 +++++++++++++++----
> > > > .../selftests/bpf/progs/get_func_ip_test.c | 20 +++---
> > > > 2 files changed, 60 insertions(+), 22 deletions(-)
> > > >
> > > > diff --git a/tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c b/tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c
> > > > index 938dbd4d7c2f..a4dab2fa2258 100644
> > > > --- a/tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c
> > > > +++ b/tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c
> > > > @@ -2,7 +2,9 @@
> > > > #include <test_progs.h>
> > > > #include "get_func_ip_test.skel.h"
> > > >
> > > > -void test_get_func_ip_test(void)
> > > > +static int config_ibt;
> > > > +
> > > > +static void test_function_entry(void)
> > > > {
> > > > struct get_func_ip_test *skel = NULL;
> > > > int err, prog_fd;
> > > > @@ -12,14 +14,6 @@ void test_get_func_ip_test(void)
> > > > if (!ASSERT_OK_PTR(skel, "get_func_ip_test__open"))
> > > > return;
> > > >
> > > > - /* test6 is x86_64 specifc because of the instruction
> > > > - * offset, disabling it for all other archs
> > > > - */
> > > > -#ifndef __x86_64__
> > > > - bpf_program__set_autoload(skel->progs.test6, false);
> > > > - bpf_program__set_autoload(skel->progs.test7, false);
> > > > -#endif
> > > > -
> > > > err = get_func_ip_test__load(skel);
> > > > if (!ASSERT_OK(err, "get_func_ip_test__load"))
> > > > goto cleanup;
> > > > @@ -38,16 +32,62 @@ void test_get_func_ip_test(void)
> > > >
> > > > ASSERT_OK(err, "test_run");
> > > >
> > > > + config_ibt = skel->bss->config_ibt;
> > >
> > > skel->bss->config_ibt isn't actually necessary, you can just check
> > > skel->kconfig->CONFIG_X86_KERNEL_IBT directly. And you won't need to
> > > trigger BPF program unnecessary, libbpf will fill out kconfig section
> > > during object/skeleton load phase.
> >
> > nice, did not know that ;-) will remove it
>
> actually.. to get kconfig datasec generated in BTF the CONFIG_X86_KERNEL_IBT
> symbol needs to be used.. so I came up with adding unused function:
>
> int unused(void)
> {
> return CONFIG_X86_KERNEL_IBT ? 0 : 1;
> }
>
> but I wonder having the config_ibt variable is better and more clear
>
> thoughts?
>
seems like it's not allowed to add __attribute__((used)) onto extern
:( I don't know, this unused function is fine with me, even if a bit
ugly (maybe just leave the comment?). I like the fact that you won't
have to run BPF program to get this config, but it's minor either way.
I feel strongly either way.
> thanks,
> jirka
