| Message ID | 20200208154209.1797988-14-jolsa@kernel.org |
|---|---|
| State | Superseded |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | bpf: Add trampoline and dispatcher to /proc/kallsyms | expand |
On Sat, Feb 8, 2020 at 7:43 AM Jiri Olsa <jolsa@kernel.org> wrote: > > Adding dispatchers to kallsyms. It's displayed as > bpf_dispatcher_<NAME> > > where NAME is the name of dispatcher. > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > include/linux/bpf.h | 19 ++++++++++++------- > kernel/bpf/dispatcher.c | 6 ++++++ > 2 files changed, 18 insertions(+), 7 deletions(-) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index b91bac10d3ea..837cdc093d2c 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -520,6 +520,7 @@ struct bpf_dispatcher { > int num_progs; > void *image; > u32 image_off; > + struct bpf_ksym ksym; > }; > > static __always_inline unsigned int bpf_dispatcher_nop_func( > @@ -535,13 +536,17 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key); > int bpf_trampoline_link_prog(struct bpf_prog *prog); > int bpf_trampoline_unlink_prog(struct bpf_prog *prog); > void bpf_trampoline_put(struct bpf_trampoline *tr); > -#define BPF_DISPATCHER_INIT(name) { \ > - .mutex = __MUTEX_INITIALIZER(name.mutex), \ > - .func = &name##_func, \ > - .progs = {}, \ > - .num_progs = 0, \ > - .image = NULL, \ > - .image_off = 0 \ > +#define BPF_DISPATCHER_INIT(_name) { \ > + .mutex = __MUTEX_INITIALIZER(_name.mutex), \ > + .func = &_name##_func, \ > + .progs = {}, \ > + .num_progs = 0, \ > + .image = NULL, \ > + .image_off = 0, \ > + .ksym = { \ > + .name = #_name, \ > + .lnode = LIST_HEAD_INIT(_name.ksym.lnode), \ > + }, \ > } > > #define DEFINE_BPF_DISPATCHER(name) \ > diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c > index b3e5b214fed8..8771d2cc5840 100644 > --- a/kernel/bpf/dispatcher.c > +++ b/kernel/bpf/dispatcher.c > @@ -152,6 +152,12 @@ void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, > if (!changed) > goto out; > > + if (!prev_num_progs) > + bpf_image_ksym_add(d->image, &d->ksym); > + > + if (!d->num_progs) > + bpf_ksym_del(&d->ksym); > + > bpf_dispatcher_update(d, prev_num_progs); On slightly unrelated note: seems like bpf_dispatcher_update won't propagate any lower-level errors back, which seems pretty bad as a bunch of stuff can go wrong. Björn, was it a conscious decision or this just slipped through the cracks? Jiri, reason I started looking at this was twofold: 1. you add/remove symbol before dispatcher is updated, which is different order from BPF trampoline updates. I think updating symbols after successful update makes more sense, no? 2. I was wondering if bpf_dispatcher_update() could return 0/1 (and <0 on error, of course), depending on whether dispatcher is present or not. Though I'm not hard set on this. > out: > mutex_unlock(&d->mutex); > -- > 2.24.1 >
On Tue, Feb 11, 2020 at 11:03:23AM -0800, Andrii Nakryiko wrote: > On Sat, Feb 8, 2020 at 7:43 AM Jiri Olsa <jolsa@kernel.org> wrote: > > > > Adding dispatchers to kallsyms. It's displayed as > > bpf_dispatcher_<NAME> > > > > where NAME is the name of dispatcher. > > > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > --- > > include/linux/bpf.h | 19 ++++++++++++------- > > kernel/bpf/dispatcher.c | 6 ++++++ > > 2 files changed, 18 insertions(+), 7 deletions(-) > > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > > index b91bac10d3ea..837cdc093d2c 100644 > > --- a/include/linux/bpf.h > > +++ b/include/linux/bpf.h > > @@ -520,6 +520,7 @@ struct bpf_dispatcher { > > int num_progs; > > void *image; > > u32 image_off; > > + struct bpf_ksym ksym; > > }; > > > > static __always_inline unsigned int bpf_dispatcher_nop_func( > > @@ -535,13 +536,17 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key); > > int bpf_trampoline_link_prog(struct bpf_prog *prog); > > int bpf_trampoline_unlink_prog(struct bpf_prog *prog); > > void bpf_trampoline_put(struct bpf_trampoline *tr); > > -#define BPF_DISPATCHER_INIT(name) { \ > > - .mutex = __MUTEX_INITIALIZER(name.mutex), \ > > - .func = &name##_func, \ > > - .progs = {}, \ > > - .num_progs = 0, \ > > - .image = NULL, \ > > - .image_off = 0 \ > > +#define BPF_DISPATCHER_INIT(_name) { \ > > + .mutex = __MUTEX_INITIALIZER(_name.mutex), \ > > + .func = &_name##_func, \ > > + .progs = {}, \ > > + .num_progs = 0, \ > > + .image = NULL, \ > > + .image_off = 0, \ > > + .ksym = { \ > > + .name = #_name, \ > > + .lnode = LIST_HEAD_INIT(_name.ksym.lnode), \ > > + }, \ > > } > > > > #define DEFINE_BPF_DISPATCHER(name) \ > > diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c > > index b3e5b214fed8..8771d2cc5840 100644 > > --- a/kernel/bpf/dispatcher.c > > +++ b/kernel/bpf/dispatcher.c > > @@ -152,6 +152,12 @@ void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, > > if (!changed) > > goto out; > > > > + if (!prev_num_progs) > > + bpf_image_ksym_add(d->image, &d->ksym); > > + > > + if (!d->num_progs) > > + bpf_ksym_del(&d->ksym); > > + > > bpf_dispatcher_update(d, prev_num_progs); > > On slightly unrelated note: seems like bpf_dispatcher_update won't > propagate any lower-level errors back, which seems pretty bad as a > bunch of stuff can go wrong. > > Björn, was it a conscious decision or this just slipped through the cracks? > > Jiri, reason I started looking at this was twofold: > 1. you add/remove symbol before dispatcher is updated, which is > different order from BPF trampoline updates. I think updating symbols > after successful update makes more sense, no? right, I guess I did not care, because there's no error returned from bpf_dispatcher_update as you pointed out.. I'll check if we can add that and add/del symbols afterwards > 2. I was wondering if bpf_dispatcher_update() could return 0/1 (and <0 > on error, of course), depending on whether dispatcher is present or > not. Though I'm not hard set on this. yes, that might be a way.. I'll check thanks, jirka
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index b91bac10d3ea..837cdc093d2c 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -520,6 +520,7 @@ struct bpf_dispatcher { int num_progs; void *image; u32 image_off; + struct bpf_ksym ksym; }; static __always_inline unsigned int bpf_dispatcher_nop_func( @@ -535,13 +536,17 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key); int bpf_trampoline_link_prog(struct bpf_prog *prog); int bpf_trampoline_unlink_prog(struct bpf_prog *prog); void bpf_trampoline_put(struct bpf_trampoline *tr); -#define BPF_DISPATCHER_INIT(name) { \ - .mutex = __MUTEX_INITIALIZER(name.mutex), \ - .func = &name##_func, \ - .progs = {}, \ - .num_progs = 0, \ - .image = NULL, \ - .image_off = 0 \ +#define BPF_DISPATCHER_INIT(_name) { \ + .mutex = __MUTEX_INITIALIZER(_name.mutex), \ + .func = &_name##_func, \ + .progs = {}, \ + .num_progs = 0, \ + .image = NULL, \ + .image_off = 0, \ + .ksym = { \ + .name = #_name, \ + .lnode = LIST_HEAD_INIT(_name.ksym.lnode), \ + }, \ } #define DEFINE_BPF_DISPATCHER(name) \ diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c index b3e5b214fed8..8771d2cc5840 100644 --- a/kernel/bpf/dispatcher.c +++ b/kernel/bpf/dispatcher.c @@ -152,6 +152,12 @@ void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, if (!changed) goto out; + if (!prev_num_progs) + bpf_image_ksym_add(d->image, &d->ksym); + + if (!d->num_progs) + bpf_ksym_del(&d->ksym); + bpf_dispatcher_update(d, prev_num_progs); out: mutex_unlock(&d->mutex);
Adding dispatchers to kallsyms. It's displayed as bpf_dispatcher_<NAME> where NAME is the name of dispatcher. Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- include/linux/bpf.h | 19 ++++++++++++------- kernel/bpf/dispatcher.c | 6 ++++++ 2 files changed, 18 insertions(+), 7 deletions(-)