| Message ID | 20230515130849.57502-3-laoar.shao@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | BPF |
| Headers | show |
| Series | bpf: bpf trampoline improvements | expand |
On Mon, May 15, 2023 at 6:09 AM Yafang Shao <laoar.shao@gmail.com> wrote: > > After commit e21aa341785c ("bpf: Fix fexit trampoline."), the selector > is only used to indicate how many times the bpf trampoline image are > updated and been displayed in the trampoline ksym name. After the > trampoline is freed, the selector will start from 0 again. So the > selector is a useless value to the user. We can remove it. > If the user want to check whether the bpf trampoline image has been updated > or not, the user can compare the address. Each time the trampoline image > is updated, the address will change consequently. > > Jiri pointed out antoher issue that perf is still using the old name > "bpf_trampoline_%lu", so this change can fix the issue in perf. > > Fixes: e21aa341785c ("bpf: Fix fexit trampoline.") > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > Cc: Song Liu <song@kernel.org> > Cc: Jiri Olsa <olsajiri@gmail.com> Acked-by: Song Liu <song@kernel.org>
On 5/15/23 5:53 PM, Song Liu wrote: > On Mon, May 15, 2023 at 6:09 AM Yafang Shao <laoar.shao@gmail.com> wrote: >> >> After commit e21aa341785c ("bpf: Fix fexit trampoline."), the selector >> is only used to indicate how many times the bpf trampoline image are >> updated and been displayed in the trampoline ksym name. After the >> trampoline is freed, the selector will start from 0 again. So the >> selector is a useless value to the user. We can remove it. >> If the user want to check whether the bpf trampoline image has been updated >> or not, the user can compare the address. Each time the trampoline image >> is updated, the address will change consequently. >> >> Jiri pointed out antoher issue that perf is still using the old name >> "bpf_trampoline_%lu", so this change can fix the issue in perf. >> >> Fixes: e21aa341785c ("bpf: Fix fexit trampoline.") >> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> >> Cc: Song Liu <song@kernel.org> >> Cc: Jiri Olsa <olsajiri@gmail.com> > > Acked-by: Song Liu <song@kernel.org> Lgtm, I took this individual one for now.
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 456f33b..36e4b2d 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1125,7 +1125,6 @@ struct bpf_trampoline { int progs_cnt[BPF_TRAMP_MAX]; /* Executable image of trampoline */ struct bpf_tramp_image *cur_image; - u64 selector; struct module *mod; }; diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 2a3849c..78acf28 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -349,7 +349,7 @@ static void bpf_tramp_image_put(struct bpf_tramp_image *im) call_rcu_tasks_trace(&im->rcu, __bpf_tramp_image_put_rcu_tasks); } -static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx) +static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key) { struct bpf_tramp_image *im; struct bpf_ksym *ksym; @@ -376,7 +376,7 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx) ksym = &im->ksym; INIT_LIST_HEAD_RCU(&ksym->lnode); - snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu_%u", key, idx); + snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu", key); bpf_image_ksym_add(image, ksym); return im; @@ -406,11 +406,10 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut err = unregister_fentry(tr, tr->cur_image->image); bpf_tramp_image_put(tr->cur_image); tr->cur_image = NULL; - tr->selector = 0; goto out; } - im = bpf_tramp_image_alloc(tr->key, tr->selector); + im = bpf_tramp_image_alloc(tr->key); if (IS_ERR(im)) { err = PTR_ERR(im); goto out; @@ -447,8 +446,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut set_memory_rox((long)im->image, 1); - WARN_ON(tr->cur_image && tr->selector == 0); - WARN_ON(!tr->cur_image && tr->selector); + WARN_ON(tr->cur_image && total == 0); if (tr->cur_image) /* progs already running at this address */ err = modify_fentry(tr, tr->cur_image->image, im->image, lock_direct_mutex); @@ -478,7 +476,6 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut if (tr->cur_image) bpf_tramp_image_put(tr->cur_image); tr->cur_image = im; - tr->selector++; out: /* If any error happens, restore previous flags */ if (err)
After commit e21aa341785c ("bpf: Fix fexit trampoline."), the selector is only used to indicate how many times the bpf trampoline image are updated and been displayed in the trampoline ksym name. After the trampoline is freed, the selector will start from 0 again. So the selector is a useless value to the user. We can remove it. If the user want to check whether the bpf trampoline image has been updated or not, the user can compare the address. Each time the trampoline image is updated, the address will change consequently. Jiri pointed out antoher issue that perf is still using the old name "bpf_trampoline_%lu", so this change can fix the issue in perf. Fixes: e21aa341785c ("bpf: Fix fexit trampoline.") Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Cc: Song Liu <song@kernel.org> Cc: Jiri Olsa <olsajiri@gmail.com> --- include/linux/bpf.h | 1 - kernel/bpf/trampoline.c | 11 ++++------- 2 files changed, 4 insertions(+), 8 deletions(-)