| Message ID | 20220510074659.2557731-3-jolsa@kernel.org (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF |
| Headers | show |
| Series | perf tools: Fix prologue generation | expand |
| Context | Check | Description |
|---|---|---|
| bpf/vmtest-bpf-next-PR | fail | merge-conflict |
| netdev/tree_selection | success | Not a local patch, async |
On Tue, May 10, 2022 at 12:47 AM Jiri Olsa <jolsa@kernel.org> wrote: > > Perf is using section name to declare special kprobe arguments, > which no longer works with current libbpf, that either requires > certain form of the section name or allows to register custom > handler. > > Adding perf support to register 'fallback' section handler to take > care of perf kprobe programs. The fallback means that it handles > any section definition besides the ones that libbpf handles. > > The handler serves two purposes: > - allows perf programs to have special arguments in section name > - allows perf to use pre-load callback where we can attach init > code (zeroing all argument registers) to each perf program > > The second is essential part of new prologue generation code, > that's coming in following patch. > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > tools/perf/util/bpf-loader.c | 47 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 47 insertions(+) > > diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c > index f8ad581ea247..2a2c9512c4e8 100644 > --- a/tools/perf/util/bpf-loader.c > +++ b/tools/perf/util/bpf-loader.c > @@ -86,6 +86,7 @@ bpf_perf_object__next(struct bpf_perf_object *prev) > (perf_obj) = (tmp), (tmp) = bpf_perf_object__next(tmp)) > > static bool libbpf_initialized; > +static int libbpf_sec_handler; > > static int bpf_perf_object__add(struct bpf_object *obj) > { > @@ -99,12 +100,58 @@ static int bpf_perf_object__add(struct bpf_object *obj) > return perf_obj ? 0 : -ENOMEM; > } > > +static struct bpf_insn prologue_init_insn[] = { > + BPF_MOV64_IMM(BPF_REG_0, 0), > + BPF_MOV64_IMM(BPF_REG_1, 0), R0 should be initialized before exit anyway. R1 contains context, so doesn't need initialization, so I think you only need R2-R5? > + BPF_MOV64_IMM(BPF_REG_2, 0), > + BPF_MOV64_IMM(BPF_REG_3, 0), > + BPF_MOV64_IMM(BPF_REG_4, 0), > + BPF_MOV64_IMM(BPF_REG_5, 0), > +}; > + > +static int libbpf_prog_prepare_load_fn(struct bpf_program *prog, > + struct bpf_prog_load_opts *opts __maybe_unused, > + long cookie __maybe_unused) > +{ > + size_t init_size_cnt = ARRAY_SIZE(prologue_init_insn); > + size_t orig_insn_cnt, insn_cnt, init_size, orig_size; > + const struct bpf_insn *orig_insn; > + struct bpf_insn *insn; > + > + /* prepend initialization code to program instructions */ > + orig_insn = bpf_program__insns(prog); > + orig_insn_cnt = bpf_program__insn_cnt(prog); > + init_size = init_size_cnt * sizeof(*insn); > + orig_size = orig_insn_cnt * sizeof(*insn); > + > + insn_cnt = orig_insn_cnt + init_size_cnt; > + insn = malloc(insn_cnt * sizeof(*insn)); > + if (!insn) > + return -ENOMEM; > + > + memcpy(insn, prologue_init_insn, init_size); > + memcpy((char *) insn + init_size, orig_insn, orig_size); > + bpf_program__set_insns(prog, insn, insn_cnt); > + return 0; > +} > + > static int libbpf_init(void) > { > + LIBBPF_OPTS(libbpf_prog_handler_opts, handler_opts, > + .prog_prepare_load_fn = libbpf_prog_prepare_load_fn, > + ); > + > if (libbpf_initialized) > return 0; > > libbpf_set_print(libbpf_perf_print); > + libbpf_sec_handler = libbpf_register_prog_handler(NULL, BPF_PROG_TYPE_KPROBE, > + 0, &handler_opts); > + if (libbpf_sec_handler < 0) { > + pr_debug("bpf: failed to register libbpf section handler: %d\n", > + libbpf_sec_handler); > + return -BPF_LOADER_ERRNO__INTERNAL; > + } > libbpf_initialized = true; > return 0; > } > -- > 2.35.3 >
On Tue, May 10, 2022 at 04:45:01PM -0700, Andrii Nakryiko wrote: > On Tue, May 10, 2022 at 12:47 AM Jiri Olsa <jolsa@kernel.org> wrote: > > > > Perf is using section name to declare special kprobe arguments, > > which no longer works with current libbpf, that either requires > > certain form of the section name or allows to register custom > > handler. > > > > Adding perf support to register 'fallback' section handler to take > > care of perf kprobe programs. The fallback means that it handles > > any section definition besides the ones that libbpf handles. > > > > The handler serves two purposes: > > - allows perf programs to have special arguments in section name > > - allows perf to use pre-load callback where we can attach init > > code (zeroing all argument registers) to each perf program > > > > The second is essential part of new prologue generation code, > > that's coming in following patch. > > > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > --- > > tools/perf/util/bpf-loader.c | 47 ++++++++++++++++++++++++++++++++++++ > > 1 file changed, 47 insertions(+) > > > > diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c > > index f8ad581ea247..2a2c9512c4e8 100644 > > --- a/tools/perf/util/bpf-loader.c > > +++ b/tools/perf/util/bpf-loader.c > > @@ -86,6 +86,7 @@ bpf_perf_object__next(struct bpf_perf_object *prev) > > (perf_obj) = (tmp), (tmp) = bpf_perf_object__next(tmp)) > > > > static bool libbpf_initialized; > > +static int libbpf_sec_handler; > > > > static int bpf_perf_object__add(struct bpf_object *obj) > > { > > @@ -99,12 +100,58 @@ static int bpf_perf_object__add(struct bpf_object *obj) > > return perf_obj ? 0 : -ENOMEM; > > } > > > > +static struct bpf_insn prologue_init_insn[] = { > > + BPF_MOV64_IMM(BPF_REG_0, 0), > > + BPF_MOV64_IMM(BPF_REG_1, 0), > > R0 should be initialized before exit anyway. R1 contains context, so > doesn't need initialization, so I think you only need R2-R5? ah right, I'll remove that thanks, jirka > > > + BPF_MOV64_IMM(BPF_REG_2, 0), > > + BPF_MOV64_IMM(BPF_REG_3, 0), > > + BPF_MOV64_IMM(BPF_REG_4, 0), > > + BPF_MOV64_IMM(BPF_REG_5, 0), > > +}; > > + > > +static int libbpf_prog_prepare_load_fn(struct bpf_program *prog, > > + struct bpf_prog_load_opts *opts __maybe_unused, > > + long cookie __maybe_unused) > > +{ > > + size_t init_size_cnt = ARRAY_SIZE(prologue_init_insn); > > + size_t orig_insn_cnt, insn_cnt, init_size, orig_size; > > + const struct bpf_insn *orig_insn; > > + struct bpf_insn *insn; > > + > > + /* prepend initialization code to program instructions */ > > + orig_insn = bpf_program__insns(prog); > > + orig_insn_cnt = bpf_program__insn_cnt(prog); > > + init_size = init_size_cnt * sizeof(*insn); > > + orig_size = orig_insn_cnt * sizeof(*insn); > > + > > + insn_cnt = orig_insn_cnt + init_size_cnt; > > + insn = malloc(insn_cnt * sizeof(*insn)); > > + if (!insn) > > + return -ENOMEM; > > + > > + memcpy(insn, prologue_init_insn, init_size); > > + memcpy((char *) insn + init_size, orig_insn, orig_size); > > + bpf_program__set_insns(prog, insn, insn_cnt); > > + return 0; > > +} > > + > > static int libbpf_init(void) > > { > > + LIBBPF_OPTS(libbpf_prog_handler_opts, handler_opts, > > + .prog_prepare_load_fn = libbpf_prog_prepare_load_fn, > > + ); > > + > > if (libbpf_initialized) > > return 0; > > > > libbpf_set_print(libbpf_perf_print); > > + libbpf_sec_handler = libbpf_register_prog_handler(NULL, BPF_PROG_TYPE_KPROBE, > > + 0, &handler_opts); > > + if (libbpf_sec_handler < 0) { > > + pr_debug("bpf: failed to register libbpf section handler: %d\n", > > + libbpf_sec_handler); > > + return -BPF_LOADER_ERRNO__INTERNAL; > > + } > > libbpf_initialized = true; > > return 0; > > } > > -- > > 2.35.3 > >
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c index f8ad581ea247..2a2c9512c4e8 100644 --- a/tools/perf/util/bpf-loader.c +++ b/tools/perf/util/bpf-loader.c @@ -86,6 +86,7 @@ bpf_perf_object__next(struct bpf_perf_object *prev) (perf_obj) = (tmp), (tmp) = bpf_perf_object__next(tmp)) static bool libbpf_initialized; +static int libbpf_sec_handler; static int bpf_perf_object__add(struct bpf_object *obj) { @@ -99,12 +100,58 @@ static int bpf_perf_object__add(struct bpf_object *obj) return perf_obj ? 0 : -ENOMEM; } +static struct bpf_insn prologue_init_insn[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_MOV64_IMM(BPF_REG_1, 0), + BPF_MOV64_IMM(BPF_REG_2, 0), + BPF_MOV64_IMM(BPF_REG_3, 0), + BPF_MOV64_IMM(BPF_REG_4, 0), + BPF_MOV64_IMM(BPF_REG_5, 0), +}; + +static int libbpf_prog_prepare_load_fn(struct bpf_program *prog, + struct bpf_prog_load_opts *opts __maybe_unused, + long cookie __maybe_unused) +{ + size_t init_size_cnt = ARRAY_SIZE(prologue_init_insn); + size_t orig_insn_cnt, insn_cnt, init_size, orig_size; + const struct bpf_insn *orig_insn; + struct bpf_insn *insn; + + /* prepend initialization code to program instructions */ + orig_insn = bpf_program__insns(prog); + orig_insn_cnt = bpf_program__insn_cnt(prog); + init_size = init_size_cnt * sizeof(*insn); + orig_size = orig_insn_cnt * sizeof(*insn); + + insn_cnt = orig_insn_cnt + init_size_cnt; + insn = malloc(insn_cnt * sizeof(*insn)); + if (!insn) + return -ENOMEM; + + memcpy(insn, prologue_init_insn, init_size); + memcpy((char *) insn + init_size, orig_insn, orig_size); + bpf_program__set_insns(prog, insn, insn_cnt); + return 0; +} + static int libbpf_init(void) { + LIBBPF_OPTS(libbpf_prog_handler_opts, handler_opts, + .prog_prepare_load_fn = libbpf_prog_prepare_load_fn, + ); + if (libbpf_initialized) return 0; libbpf_set_print(libbpf_perf_print); + libbpf_sec_handler = libbpf_register_prog_handler(NULL, BPF_PROG_TYPE_KPROBE, + 0, &handler_opts); + if (libbpf_sec_handler < 0) { + pr_debug("bpf: failed to register libbpf section handler: %d\n", + libbpf_sec_handler); + return -BPF_LOADER_ERRNO__INTERNAL; + } libbpf_initialized = true; return 0; }
Perf is using section name to declare special kprobe arguments, which no longer works with current libbpf, that either requires certain form of the section name or allows to register custom handler. Adding perf support to register 'fallback' section handler to take care of perf kprobe programs. The fallback means that it handles any section definition besides the ones that libbpf handles. The handler serves two purposes: - allows perf programs to have special arguments in section name - allows perf to use pre-load callback where we can attach init code (zeroing all argument registers) to each perf program The second is essential part of new prologue generation code, that's coming in following patch. Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- tools/perf/util/bpf-loader.c | 47 ++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+)