[PATCH bpf-next v5 0/2] bpf: enable some functions in cgroup programs

[PATCH bpf-next v5 0/2] bpf: enable some functions in cgroup programs

[Matteo Croce]

From: Matteo Croce <teknoraver@meta.com>

Enable some BPF kfuncs and the helper bpf_current_task_under_cgroup()
for program types BPF_CGROUP_*.
These will be used by systemd-networkd:
https://github.com/systemd/systemd/pull/32212

v4->v5:
Same code, but v4 had an old cover letter

v3->v4:
Reset all the acked-by tags because the code changed a bit.

Signed-off-by: Matteo Croce <teknoraver@meta.com>

Matteo Croce (2):
  bpf: enable generic kfuncs for BPF_CGROUP_* programs
  bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP_*

 include/linux/bpf.h      |  1 +
 kernel/bpf/btf.c         |  8 ++++++--
 kernel/bpf/cgroup.c      |  2 ++
 kernel/bpf/helpers.c     | 29 +++++++++++++++++++++++++++++
 kernel/trace/bpf_trace.c | 23 -----------------------
 5 files changed, 38 insertions(+), 25 deletions(-)

-- 
2.46.0

[PATCH bpf-next v5 1/2] bpf: enable generic kfuncs for BPF_CGROUP_* programs

[Matteo Croce]

From: Matteo Croce <teknoraver@meta.com>

These kfuncs are enabled even in BPF_PROG_TYPE_TRACING, so they
should be safe also in BPF_CGROUP_* programs.

In enum btf_kfunc_hook, rename BTF_KFUNC_HOOK_CGROUP_SKB to a more
generic BTF_KFUNC_HOOK_CGROUP, since it's used for all the cgroup
related program types.

Signed-off-by: Matteo Croce <teknoraver@meta.com>
---
 kernel/bpf/btf.c     | 8 ++++++--
 kernel/bpf/helpers.c | 6 ++++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 95426d5b634e..08d094875f00 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -212,7 +212,7 @@ enum btf_kfunc_hook {
 	BTF_KFUNC_HOOK_TRACING,
 	BTF_KFUNC_HOOK_SYSCALL,
 	BTF_KFUNC_HOOK_FMODRET,
-	BTF_KFUNC_HOOK_CGROUP_SKB,
+	BTF_KFUNC_HOOK_CGROUP,
 	BTF_KFUNC_HOOK_SCHED_ACT,
 	BTF_KFUNC_HOOK_SK_SKB,
 	BTF_KFUNC_HOOK_SOCKET_FILTER,
@@ -8312,8 +8312,12 @@ static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
 	case BPF_PROG_TYPE_SYSCALL:
 		return BTF_KFUNC_HOOK_SYSCALL;
 	case BPF_PROG_TYPE_CGROUP_SKB:
+	case BPF_PROG_TYPE_CGROUP_SOCK:
+	case BPF_PROG_TYPE_CGROUP_DEVICE:
 	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
-		return BTF_KFUNC_HOOK_CGROUP_SKB;
+	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
+	case BPF_PROG_TYPE_CGROUP_SYSCTL:
+		return BTF_KFUNC_HOOK_CGROUP;
 	case BPF_PROG_TYPE_SCHED_ACT:
 		return BTF_KFUNC_HOOK_SCHED_ACT;
 	case BPF_PROG_TYPE_SK_SKB:
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index d02ae323996b..0d1d97d968b0 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -3052,6 +3052,12 @@ static int __init kfunc_init(void)
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &generic_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &generic_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &generic_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SKB, &generic_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCK, &generic_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_DEVICE, &generic_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCK_ADDR, &generic_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SYSCTL, &generic_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCKOPT, &generic_kfunc_set);
 	ret = ret ?: register_btf_id_dtor_kfuncs(generic_dtors,
 						  ARRAY_SIZE(generic_dtors),
 						  THIS_MODULE);
-- 
2.46.0

[PATCH bpf-next v5 2/2] bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP_*

[Matteo Croce]

From: Matteo Croce <teknoraver@meta.com>

The helper bpf_current_task_under_cgroup() currently is only allowed for
tracing programs, allow its usage also in the BPF_CGROUP_* program types.

Move the code from kernel/trace/bpf_trace.c to kernel/bpf/helpers.c,
so it compiles also without CONFIG_BPF_EVENTS.

This will be used in systemd-networkd to monitor the sysctl writes,
and filter it's own writes from others:
https://github.com/systemd/systemd/pull/32212

Signed-off-by: Matteo Croce <teknoraver@meta.com>
---
 include/linux/bpf.h      |  1 +
 kernel/bpf/cgroup.c      |  2 ++
 kernel/bpf/helpers.c     | 23 +++++++++++++++++++++++
 kernel/trace/bpf_trace.c | 23 -----------------------
 4 files changed, 26 insertions(+), 23 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b9425e410bcb..f0192c173ed8 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -3206,6 +3206,7 @@ extern const struct bpf_func_proto bpf_sock_hash_update_proto;
 extern const struct bpf_func_proto bpf_get_current_cgroup_id_proto;
 extern const struct bpf_func_proto bpf_get_current_ancestor_cgroup_id_proto;
 extern const struct bpf_func_proto bpf_get_cgroup_classid_curr_proto;
+extern const struct bpf_func_proto bpf_current_task_under_cgroup_proto;
 extern const struct bpf_func_proto bpf_msg_redirect_hash_proto;
 extern const struct bpf_func_proto bpf_msg_redirect_map_proto;
 extern const struct bpf_func_proto bpf_sk_redirect_hash_proto;
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 8ba73042a239..e7113d700b87 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -2581,6 +2581,8 @@ cgroup_current_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	case BPF_FUNC_get_cgroup_classid:
 		return &bpf_get_cgroup_classid_curr_proto;
 #endif
+	case BPF_FUNC_current_task_under_cgroup:
+		return &bpf_current_task_under_cgroup_proto;
 	default:
 		return NULL;
 	}
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 0d1d97d968b0..8502cfed2926 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2458,6 +2458,29 @@ __bpf_kfunc long bpf_task_under_cgroup(struct task_struct *task,
 	return ret;
 }
 
+BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
+{
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+	struct cgroup *cgrp;
+
+	if (unlikely(idx >= array->map.max_entries))
+		return -E2BIG;
+
+	cgrp = READ_ONCE(array->ptrs[idx]);
+	if (unlikely(!cgrp))
+		return -EAGAIN;
+
+	return task_under_cgroup_hierarchy(current, cgrp);
+}
+
+const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
+	.func           = bpf_current_task_under_cgroup,
+	.gpl_only       = false,
+	.ret_type       = RET_INTEGER,
+	.arg1_type      = ARG_CONST_MAP_PTR,
+	.arg2_type      = ARG_ANYTHING,
+};
+
 /**
  * bpf_task_get_cgroup1 - Acquires the associated cgroup of a task within a
  * specific cgroup1 hierarchy. The cgroup1 hierarchy is identified by its
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index d557bb11e0ff..e4e1f5d8b2a6 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -797,29 +797,6 @@ const struct bpf_func_proto bpf_task_pt_regs_proto = {
 	.ret_btf_id	= &bpf_task_pt_regs_ids[0],
 };
 
-BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
-{
-	struct bpf_array *array = container_of(map, struct bpf_array, map);
-	struct cgroup *cgrp;
-
-	if (unlikely(idx >= array->map.max_entries))
-		return -E2BIG;
-
-	cgrp = READ_ONCE(array->ptrs[idx]);
-	if (unlikely(!cgrp))
-		return -EAGAIN;
-
-	return task_under_cgroup_hierarchy(current, cgrp);
-}
-
-static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
-	.func           = bpf_current_task_under_cgroup,
-	.gpl_only       = false,
-	.ret_type       = RET_INTEGER,
-	.arg1_type      = ARG_CONST_MAP_PTR,
-	.arg2_type      = ARG_ANYTHING,
-};
-
 struct send_signal_irq_work {
 	struct irq_work irq_work;
 	struct task_struct *task;
-- 
2.46.0

Re: [PATCH bpf-next v5 2/2] bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP_*

[kernel test robot]

Hi Matteo,

kernel test robot noticed the following build errors:

[auto build test ERROR on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Matteo-Croce/bpf-enable-generic-kfuncs-for-BPF_CGROUP_-programs/20240815-000517
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20240813132831.184362-3-technoboy85%40gmail.com
patch subject: [PATCH bpf-next v5 2/2] bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP_*
config: arm-randconfig-003-20240815 (https://download.01.org/0day-ci/archive/20240815/202408152026.xtFpPaaI-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240815/202408152026.xtFpPaaI-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408152026.xtFpPaaI-lkp@intel.com/

All errors (new ones prefixed by >>):

   arm-linux-gnueabi-ld: kernel/trace/bpf_trace.o: in function `bpf_tracing_func_proto':
>> bpf_trace.c:(.text+0x41bc): undefined reference to `bpf_current_task_under_cgroup_proto'

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH bpf-next v5 1/2] bpf: enable generic kfuncs for BPF_CGROUP_* programs

[Andrii Nakryiko]

On Tue, Aug 13, 2024 at 6:28 AM Matteo Croce <technoboy85@gmail.com> wrote:
>
> From: Matteo Croce <teknoraver@meta.com>
>
> These kfuncs are enabled even in BPF_PROG_TYPE_TRACING, so they
> should be safe also in BPF_CGROUP_* programs.
>
> In enum btf_kfunc_hook, rename BTF_KFUNC_HOOK_CGROUP_SKB to a more
> generic BTF_KFUNC_HOOK_CGROUP, since it's used for all the cgroup
> related program types.
>
> Signed-off-by: Matteo Croce <teknoraver@meta.com>
> ---
>  kernel/bpf/btf.c     | 8 ++++++--
>  kernel/bpf/helpers.c | 6 ++++++
>  2 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index 95426d5b634e..08d094875f00 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -212,7 +212,7 @@ enum btf_kfunc_hook {
>         BTF_KFUNC_HOOK_TRACING,
>         BTF_KFUNC_HOOK_SYSCALL,
>         BTF_KFUNC_HOOK_FMODRET,
> -       BTF_KFUNC_HOOK_CGROUP_SKB,
> +       BTF_KFUNC_HOOK_CGROUP,
>         BTF_KFUNC_HOOK_SCHED_ACT,
>         BTF_KFUNC_HOOK_SK_SKB,
>         BTF_KFUNC_HOOK_SOCKET_FILTER,
> @@ -8312,8 +8312,12 @@ static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
>         case BPF_PROG_TYPE_SYSCALL:
>                 return BTF_KFUNC_HOOK_SYSCALL;
>         case BPF_PROG_TYPE_CGROUP_SKB:
> +       case BPF_PROG_TYPE_CGROUP_SOCK:
> +       case BPF_PROG_TYPE_CGROUP_DEVICE:
>         case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
> -               return BTF_KFUNC_HOOK_CGROUP_SKB;
> +       case BPF_PROG_TYPE_CGROUP_SOCKOPT:
> +       case BPF_PROG_TYPE_CGROUP_SYSCTL:
> +               return BTF_KFUNC_HOOK_CGROUP;
>         case BPF_PROG_TYPE_SCHED_ACT:
>                 return BTF_KFUNC_HOOK_SCHED_ACT;
>         case BPF_PROG_TYPE_SK_SKB:
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index d02ae323996b..0d1d97d968b0 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -3052,6 +3052,12 @@ static int __init kfunc_init(void)
>         ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &generic_kfunc_set);
>         ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &generic_kfunc_set);
>         ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &generic_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SKB, &generic_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCK, &generic_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_DEVICE, &generic_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCK_ADDR, &generic_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SYSCTL, &generic_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCKOPT, &generic_kfunc_set);

So given all those CGROUP_xxx program types map to the same
cgroup-generic BTF_KFUNC_HOOK_CGROUP hook, why do we need 6
repetitions of the same thing?

I'd say let's keep just one (pick any, CGROUP_SKB, for example)
registration. And then we should follow up with cleaning up
register_btf_kfunc_id_set() to accept hook type, not program type. And
then it will be clean and will make most sense.

But other than that looks good to me.

pw-bot: cr


>         ret = ret ?: register_btf_id_dtor_kfuncs(generic_dtors,
>                                                   ARRAY_SIZE(generic_dtors),
>                                                   THIS_MODULE);
> --
> 2.46.0
>

Re: [PATCH bpf-next v5 2/2] bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP_*

[Andrii Nakryiko]

On Tue, Aug 13, 2024 at 6:28 AM Matteo Croce <technoboy85@gmail.com> wrote:
>
> From: Matteo Croce <teknoraver@meta.com>
>
> The helper bpf_current_task_under_cgroup() currently is only allowed for
> tracing programs, allow its usage also in the BPF_CGROUP_* program types.
>
> Move the code from kernel/trace/bpf_trace.c to kernel/bpf/helpers.c,
> so it compiles also without CONFIG_BPF_EVENTS.
>
> This will be used in systemd-networkd to monitor the sysctl writes,
> and filter it's own writes from others:
> https://github.com/systemd/systemd/pull/32212
>
> Signed-off-by: Matteo Croce <teknoraver@meta.com>
> ---
>  include/linux/bpf.h      |  1 +
>  kernel/bpf/cgroup.c      |  2 ++
>  kernel/bpf/helpers.c     | 23 +++++++++++++++++++++++
>  kernel/trace/bpf_trace.c | 23 -----------------------
>  4 files changed, 26 insertions(+), 23 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index b9425e410bcb..f0192c173ed8 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -3206,6 +3206,7 @@ extern const struct bpf_func_proto bpf_sock_hash_update_proto;
>  extern const struct bpf_func_proto bpf_get_current_cgroup_id_proto;
>  extern const struct bpf_func_proto bpf_get_current_ancestor_cgroup_id_proto;
>  extern const struct bpf_func_proto bpf_get_cgroup_classid_curr_proto;
> +extern const struct bpf_func_proto bpf_current_task_under_cgroup_proto;
>  extern const struct bpf_func_proto bpf_msg_redirect_hash_proto;
>  extern const struct bpf_func_proto bpf_msg_redirect_map_proto;
>  extern const struct bpf_func_proto bpf_sk_redirect_hash_proto;
> diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
> index 8ba73042a239..e7113d700b87 100644
> --- a/kernel/bpf/cgroup.c
> +++ b/kernel/bpf/cgroup.c
> @@ -2581,6 +2581,8 @@ cgroup_current_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
>         case BPF_FUNC_get_cgroup_classid:
>                 return &bpf_get_cgroup_classid_curr_proto;
>  #endif
> +       case BPF_FUNC_current_task_under_cgroup:
> +               return &bpf_current_task_under_cgroup_proto;
>         default:
>                 return NULL;
>         }
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index 0d1d97d968b0..8502cfed2926 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -2458,6 +2458,29 @@ __bpf_kfunc long bpf_task_under_cgroup(struct task_struct *task,
>         return ret;
>  }
>
> +BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
> +{
> +       struct bpf_array *array = container_of(map, struct bpf_array, map);
> +       struct cgroup *cgrp;
> +
> +       if (unlikely(idx >= array->map.max_entries))
> +               return -E2BIG;
> +
> +       cgrp = READ_ONCE(array->ptrs[idx]);
> +       if (unlikely(!cgrp))
> +               return -EAGAIN;
> +
> +       return task_under_cgroup_hierarchy(current, cgrp);
> +}
> +
> +const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
> +       .func           = bpf_current_task_under_cgroup,
> +       .gpl_only       = false,
> +       .ret_type       = RET_INTEGER,
> +       .arg1_type      = ARG_CONST_MAP_PTR,
> +       .arg2_type      = ARG_ANYTHING,
> +};
> +
>  /**
>   * bpf_task_get_cgroup1 - Acquires the associated cgroup of a task within a
>   * specific cgroup1 hierarchy. The cgroup1 hierarchy is identified by its
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index d557bb11e0ff..e4e1f5d8b2a6 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -797,29 +797,6 @@ const struct bpf_func_proto bpf_task_pt_regs_proto = {
>         .ret_btf_id     = &bpf_task_pt_regs_ids[0],
>  };
>
> -BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
> -{
> -       struct bpf_array *array = container_of(map, struct bpf_array, map);
> -       struct cgroup *cgrp;
> -
> -       if (unlikely(idx >= array->map.max_entries))
> -               return -E2BIG;
> -
> -       cgrp = READ_ONCE(array->ptrs[idx]);
> -       if (unlikely(!cgrp))
> -               return -EAGAIN;
> -
> -       return task_under_cgroup_hierarchy(current, cgrp);
> -}
> -
> -static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
> -       .func           = bpf_current_task_under_cgroup,
> -       .gpl_only       = false,
> -       .ret_type       = RET_INTEGER,
> -       .arg1_type      = ARG_CONST_MAP_PTR,
> -       .arg2_type      = ARG_ANYTHING,
> -};
> -

Seems like you need to adjust bpf_tracing_func_proto() function and
move BPF_FUNC_current_task_under_cgroup into #ifdef CONFIG_CGROUPS
block together with cgrp_storage_get and delete.

>  struct send_signal_irq_work {
>         struct irq_work irq_work;
>         struct task_struct *task;
> --
> 2.46.0
>

Re: [PATCH bpf-next v5 2/2] bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP_*

[kernel test robot]

Hi Matteo,

kernel test robot noticed the following build errors:

[auto build test ERROR on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Matteo-Croce/bpf-enable-generic-kfuncs-for-BPF_CGROUP_-programs/20240815-000517
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20240813132831.184362-3-technoboy85%40gmail.com
patch subject: [PATCH bpf-next v5 2/2] bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP_*
config: i386-buildonly-randconfig-002-20240816 (https://download.01.org/0day-ci/archive/20240816/202408161356.OvFB1jZi-lkp@intel.com/config)
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240816/202408161356.OvFB1jZi-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408161356.OvFB1jZi-lkp@intel.com/

All errors (new ones prefixed by >>):

>> ld.lld: error: undefined symbol: bpf_current_task_under_cgroup_proto
   >>> referenced by bpf_trace.c
   >>>               kernel/trace/bpf_trace.o:(bpf_tracing_func_proto) in archive vmlinux.a

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