On Wed, May 12, 2021 at 2:33 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> From: Alexei Starovoitov <ast@xxxxxxxxxx>
>
> Add -L flag to bpftool to use libbpf gen_trace facility and syscall/loader program
> for skeleton generation and program loading.
>
> "bpftool gen skeleton -L" command will generate a "light skeleton" or "loader skeleton"
> that is similar to existing skeleton, but has one major difference:
> $ bpftool gen skeleton lsm.o > lsm.skel.h
> $ bpftool gen skeleton -L lsm.o > lsm.lskel.h
> $ diff lsm.skel.h lsm.lskel.h
> @@ -5,34 +4,34 @@
> #define __LSM_SKEL_H__
>
> #include <stdlib.h>
> -#include <bpf/libbpf.h>
> +#include <bpf/bpf.h>
>
> The light skeleton does not use majority of libbpf infrastructure.
> It doesn't need libelf. It doesn't parse .o file.
> It only needs few sys_bpf wrappers. All of them are in bpf/bpf.h file.
> In future libbpf/bpf.c can be inlined into bpf.h, so not even libbpf.a would be
> needed to work with light skeleton.
>
> "bpftool prog load -L file.o" command is introduced for debugging of syscall/loader
> program generation. Just like the same command without -L it will try to load
> the programs from file.o into the kernel. It won't even try to pin them.
>
> "bpftool prog load -L -d file.o" command will provide additional debug messages
> on how syscall/loader program was generated.
> Also the execution of syscall/loader program will use bpf_trace_printk() for
> each step of loading BTF, creating maps, and loading programs.
> The user can do "cat /.../trace_pipe" for further debug.
>
> An example of fexit_sleep.lskel.h generated from progs/fexit_sleep.c:
> struct fexit_sleep {
> struct bpf_loader_ctx ctx;
> struct {
> struct bpf_map_desc bss;
> } maps;
> struct {
> struct bpf_prog_desc nanosleep_fentry;
> struct bpf_prog_desc nanosleep_fexit;
> } progs;
> struct {
> int nanosleep_fentry_fd;
> int nanosleep_fexit_fd;
> } links;
> struct fexit_sleep__bss {
> int pid;
> int fentry_cnt;
> int fexit_cnt;
> } *bss;
> };
>
> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
> ---
LGTM.
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> tools/bpf/bpftool/Makefile | 2 +-
> tools/bpf/bpftool/gen.c | 386 ++++++++++++++++++++++++++++--
> tools/bpf/bpftool/main.c | 7 +-
> tools/bpf/bpftool/main.h | 1 +
> tools/bpf/bpftool/prog.c | 107 ++++++++-
> tools/bpf/bpftool/xlated_dumper.c | 3 +
> 6 files changed, 482 insertions(+), 24 deletions(-)
>
[...]
