| Message ID | 20200226130345.209469-13-jolsa@kernel.org |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | bpf: Add trampoline and dispatcher to /proc/kallsyms | expand |
On Wed, Feb 26, 2020 at 5:07 AM Jiri Olsa <jolsa@kernel.org> wrote: > > Adding trampolines to kallsyms. It's displayed as > bpf_trampoline_<ID> [bpf] > > where ID is the BTF id of the trampoline function. > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Song Liu <songliubraving@fb.com>
On Wed, Feb 26, 2020 at 02:03:39PM +0100, Jiri Olsa wrote: > Adding trampolines to kallsyms. It's displayed as > bpf_trampoline_<ID> [bpf] > > where ID is the BTF id of the trampoline function. > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > include/linux/bpf.h | 3 +++ > kernel/bpf/trampoline.c | 38 +++++++++++++++++++++++++++++++++++++- > 2 files changed, 40 insertions(+), 1 deletion(-) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 76934893bccf..c216af89254f 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -502,6 +502,7 @@ struct bpf_trampoline { > /* Executable image of trampoline */ > void *image; > u64 selector; > + struct bpf_ksym ksym; > }; > > #define BPF_DISPATCHER_MAX 48 /* Fits in 2048B */ > @@ -573,6 +574,8 @@ struct bpf_image { > #define BPF_IMAGE_SIZE (PAGE_SIZE - sizeof(struct bpf_image)) > bool is_bpf_image_address(unsigned long address); > void *bpf_image_alloc(void); > +void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym); > +void bpf_image_ksym_del(struct bpf_ksym *ksym); > /* Called only from code, so there's no need for stubs. */ > void bpf_ksym_add(struct bpf_ksym *ksym); > void bpf_ksym_del(struct bpf_ksym *ksym); > diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c > index 6b264a92064b..4b0ae976a6eb 100644 > --- a/kernel/bpf/trampoline.c > +++ b/kernel/bpf/trampoline.c > @@ -5,6 +5,7 @@ > #include <linux/filter.h> > #include <linux/ftrace.h> > #include <linux/rbtree_latch.h> > +#include <linux/perf_event.h> > > /* dummy _ops. The verifier will operate on target program's ops. */ > const struct bpf_verifier_ops bpf_extension_verifier_ops = { > @@ -96,6 +97,22 @@ bool is_bpf_image_address(unsigned long addr) > return ret; > } > > +void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym) > +{ > + ksym->start = (unsigned long) data; > + ksym->end = ksym->start + BPF_IMAGE_SIZE; > + bpf_ksym_add(ksym); > + perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, > + BPF_IMAGE_SIZE, false, ksym->name); > +} > + > +void bpf_image_ksym_del(struct bpf_ksym *ksym) > +{ > + bpf_ksym_del(ksym); > + perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, > + BPF_IMAGE_SIZE, true, ksym->name); > +} > + > struct bpf_trampoline *bpf_trampoline_lookup(u64 key) > { > struct bpf_trampoline *tr; > @@ -131,6 +148,7 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key) > for (i = 0; i < BPF_TRAMP_MAX; i++) > INIT_HLIST_HEAD(&tr->progs_hlist[i]); > tr->image = image; > + INIT_LIST_HEAD_RCU(&tr->ksym.lnode); > out: > mutex_unlock(&trampoline_mutex); > return tr; > @@ -267,6 +285,14 @@ static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(enum bpf_attach_type t) > } > } > > +static void bpf_trampoline_ksym_add(struct bpf_trampoline *tr) > +{ > + struct bpf_ksym *ksym = &tr->ksym; > + > + snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu", tr->key); Do you have plan to support struct_ops which is also using trampoline (in bpf_struct_ops_map_update_elem())? Any idea on the name? bpf_struct_ops_<map_id>? > + bpf_image_ksym_add(tr->image, ksym); > +} > +
On Wed, Feb 26, 2020 at 10:26:40PM -0800, Martin KaFai Lau wrote: SNIP > > + ksym->start = (unsigned long) data; > > + ksym->end = ksym->start + BPF_IMAGE_SIZE; > > + bpf_ksym_add(ksym); > > + perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, > > + BPF_IMAGE_SIZE, false, ksym->name); > > +} > > + > > +void bpf_image_ksym_del(struct bpf_ksym *ksym) > > +{ > > + bpf_ksym_del(ksym); > > + perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, > > + BPF_IMAGE_SIZE, true, ksym->name); > > +} > > + > > struct bpf_trampoline *bpf_trampoline_lookup(u64 key) > > { > > struct bpf_trampoline *tr; > > @@ -131,6 +148,7 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key) > > for (i = 0; i < BPF_TRAMP_MAX; i++) > > INIT_HLIST_HEAD(&tr->progs_hlist[i]); > > tr->image = image; > > + INIT_LIST_HEAD_RCU(&tr->ksym.lnode); > > out: > > mutex_unlock(&trampoline_mutex); > > return tr; > > @@ -267,6 +285,14 @@ static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(enum bpf_attach_type t) > > } > > } > > > > +static void bpf_trampoline_ksym_add(struct bpf_trampoline *tr) > > +{ > > + struct bpf_ksym *ksym = &tr->ksym; > > + > > + snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu", tr->key); > Do you have plan to support struct_ops which is also using > trampoline (in bpf_struct_ops_map_update_elem())? > Any idea on the name? bpf_struct_ops_<map_id>? right, I was wondering we should also do that, I'll check on it jirka
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 76934893bccf..c216af89254f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -502,6 +502,7 @@ struct bpf_trampoline { /* Executable image of trampoline */ void *image; u64 selector; + struct bpf_ksym ksym; }; #define BPF_DISPATCHER_MAX 48 /* Fits in 2048B */ @@ -573,6 +574,8 @@ struct bpf_image { #define BPF_IMAGE_SIZE (PAGE_SIZE - sizeof(struct bpf_image)) bool is_bpf_image_address(unsigned long address); void *bpf_image_alloc(void); +void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym); +void bpf_image_ksym_del(struct bpf_ksym *ksym); /* Called only from code, so there's no need for stubs. */ void bpf_ksym_add(struct bpf_ksym *ksym); void bpf_ksym_del(struct bpf_ksym *ksym); diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 6b264a92064b..4b0ae976a6eb 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -5,6 +5,7 @@ #include <linux/filter.h> #include <linux/ftrace.h> #include <linux/rbtree_latch.h> +#include <linux/perf_event.h> /* dummy _ops. The verifier will operate on target program's ops. */ const struct bpf_verifier_ops bpf_extension_verifier_ops = { @@ -96,6 +97,22 @@ bool is_bpf_image_address(unsigned long addr) return ret; } +void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym) +{ + ksym->start = (unsigned long) data; + ksym->end = ksym->start + BPF_IMAGE_SIZE; + bpf_ksym_add(ksym); + perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, + BPF_IMAGE_SIZE, false, ksym->name); +} + +void bpf_image_ksym_del(struct bpf_ksym *ksym) +{ + bpf_ksym_del(ksym); + perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start, + BPF_IMAGE_SIZE, true, ksym->name); +} + struct bpf_trampoline *bpf_trampoline_lookup(u64 key) { struct bpf_trampoline *tr; @@ -131,6 +148,7 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key) for (i = 0; i < BPF_TRAMP_MAX; i++) INIT_HLIST_HEAD(&tr->progs_hlist[i]); tr->image = image; + INIT_LIST_HEAD_RCU(&tr->ksym.lnode); out: mutex_unlock(&trampoline_mutex); return tr; @@ -267,6 +285,14 @@ static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(enum bpf_attach_type t) } } +static void bpf_trampoline_ksym_add(struct bpf_trampoline *tr) +{ + struct bpf_ksym *ksym = &tr->ksym; + + snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu", tr->key); + bpf_image_ksym_add(tr->image, ksym); +} + int bpf_trampoline_link_prog(struct bpf_prog *prog) { enum bpf_tramp_prog_type kind; @@ -291,6 +317,10 @@ int bpf_trampoline_link_prog(struct bpf_prog *prog) err = -EBUSY; goto out; } + /* With cnt == 0 image is not used (no symbol in kallsyms) + * and will not be used for BPF_PROG_TYPE_EXT prog type, + * so there's no symbol added for this case. + */ tr->extension_prog = prog; err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL, prog->bpf_func); @@ -311,7 +341,10 @@ int bpf_trampoline_link_prog(struct bpf_prog *prog) if (err) { hlist_del(&prog->aux->tramp_hlist); tr->progs_cnt[kind]--; + goto out; } + if (cnt == 0) + bpf_trampoline_ksym_add(tr); out: mutex_unlock(&tr->mutex); return err; @@ -322,7 +355,7 @@ int bpf_trampoline_unlink_prog(struct bpf_prog *prog) { enum bpf_tramp_prog_type kind; struct bpf_trampoline *tr; - int err; + int err, cnt; tr = prog->aux->trampoline; kind = bpf_attach_type_to_tramp(prog->expected_attach_type); @@ -336,6 +369,9 @@ int bpf_trampoline_unlink_prog(struct bpf_prog *prog) } hlist_del(&prog->aux->tramp_hlist); tr->progs_cnt[kind]--; + cnt = tr->progs_cnt[BPF_TRAMP_FENTRY] + tr->progs_cnt[BPF_TRAMP_FEXIT]; + if (cnt == 0) + bpf_image_ksym_del(&tr->ksym); err = bpf_trampoline_update(prog->aux->trampoline); out: mutex_unlock(&tr->mutex);
Adding trampolines to kallsyms. It's displayed as bpf_trampoline_<ID> [bpf] where ID is the BTF id of the trampoline function. Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- include/linux/bpf.h | 3 +++ kernel/bpf/trampoline.c | 38 +++++++++++++++++++++++++++++++++++++- 2 files changed, 40 insertions(+), 1 deletion(-)