On Wed, May 18, 2022 at 04:50:58PM -0700, Andrii Nakryiko wrote:
> On Tue, May 17, 2022 at 12:37 AM Eugene Syromiatnikov <esyr@xxxxxxxxxx> wrote:
> >
> > With the interface as defined, it is impossible to pass 64-bit kernel
> > addresses from a 32-bit userspace process in BPF_LINK_TYPE_KPROBE_MULTI,
> > which severly limits the useability of the interface, change the ABI
> > to accept an array of u64 values instead of (kernel? user?) longs.
> > Interestingly, the rest of the libbpf infrastructure uses 64-bit values
> > for kallsyms addresses already, so this patch also eliminates
> > the sym_addr cast in tools/lib/bpf/libbpf.c:resolve_kprobe_multi_cb().
> >
> > Fixes: 0dcac272540613d4 ("bpf: Add multi kprobe link")
> > Fixes: 5117c26e877352bc ("libbpf: Add bpf_link_create support for multi kprobes")
> > Fixes: ddc6b04989eb0993 ("libbpf: Add bpf_program__attach_kprobe_multi_opts function")
> > Fixes: f7a11eeccb111854 ("selftests/bpf: Add kprobe_multi attach test")
> > Fixes: 9271a0c7ae7a9147 ("selftests/bpf: Add attach test for bpf_program__attach_kprobe_multi_opts")
> > Fixes: 2c6401c966ae1fbe ("selftests/bpf: Add kprobe_multi bpf_cookie test")
> > Signed-off-by: Eugene Syromiatnikov <esyr@xxxxxxxxxx>
> > ---
> > kernel/trace/bpf_trace.c | 25 ++++++++++++++++++----
>
> kernel changes should go into a separate patch
Sure, they can be split, the only reason they are this way is to keep
API/ABI in sync between the kernel code and the user space one.
> (and seems like they
> logically fit together with patch #3, no?)
Patch #3 doesn't change the API/ABI, it only fixes the implementation
in terms of compat handling (and it is more straightforward),
that is why I decided to have it separately. The compat handling
of addrs, on the other hand, can't be fixed without the ABI change.
> > tools/lib/bpf/bpf.h | 2 +-
> > tools/lib/bpf/libbpf.c | 8 +++----
> > tools/lib/bpf/libbpf.h | 2 +-
> > .../testing/selftests/bpf/prog_tests/bpf_cookie.c | 2 +-
> > .../selftests/bpf/prog_tests/kprobe_multi_test.c | 8 +++----
> > 6 files changed, 32 insertions(+), 15 deletions(-)
> >
>
> [...]
>
