* [PATCH bpf-next] selftests/bpf: fix build with new LLVM
@ 2025-09-18 9:36 Anton Protopopov
2025-09-18 15:02 ` Alexei Starovoitov
0 siblings, 1 reply; 6+ messages in thread
From: Anton Protopopov @ 2025-09-18 9:36 UTC (permalink / raw)
To: bpf; +Cc: Anton Protopopov, Puranjay Mohan
The progs/stream.c BPF program now uses arena helpers, so it includes
bpf_arena_common.h, which conflicts with the declarations generated
in vmlinux.h. This leads to the following build errors with the recent
LLVM:
In file included from progs/stream.c:8:
.../tools/testing/selftests/bpf/bpf_arena_common.h:47:15: error: conflicting types for 'bpf_arena_alloc_pages'
47 | void __arena* bpf_arena_alloc_pages(void *map, void __arena *addr, __u32 page_cnt,
| ^
.../tools/testing/selftests/bpf/tools/include/vmlinux.h:229284:14: note: previous declaration is here
229284 | extern void *bpf_arena_alloc_pages(void *p__map, void *addr__ign, u32 page_cnt, int node_id, u64 flags) __weak __ksym;
| ^
... etc
Fix this by analogy with the 6a8260147745 ("bpf: selftests: Do not
use generated kfunc prototypes for arena progs") commit by adding the
BPF_NO_KFUNC_PROTOTYPES. As the test uses other kfuncs, declare them
specifically.
Fixes: 86f2225065be ("selftests/bpf: Add tests for arena fault reporting")
Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
---
tools/testing/selftests/bpf/progs/stream.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/stream.c b/tools/testing/selftests/bpf/progs/stream.c
index 4a5bd852f10c..900da666d182 100644
--- a/tools/testing/selftests/bpf/progs/stream.c
+++ b/tools/testing/selftests/bpf/progs/stream.c
@@ -1,5 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+
+#define BPF_NO_KFUNC_PROTOTYPES
#include <vmlinux.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_helpers.h>
@@ -7,6 +9,13 @@
#include "bpf_experimental.h"
#include "bpf_arena_common.h"
+/*
+ * Declare kfuncs here, as BPF_NO_KFUNC_PROTOTYPES is used
+ * to exclude improper arena kfuncs declarations
+ */
+extern int bpf_res_spin_lock(struct bpf_res_spin_lock *lock) __weak __ksym;
+extern void bpf_res_spin_unlock(struct bpf_res_spin_lock *lock) __weak __ksym;
+
struct arr_elem {
struct bpf_res_spin_lock lock;
};
--
2.34.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: fix build with new LLVM
2025-09-18 9:36 [PATCH bpf-next] selftests/bpf: fix build with new LLVM Anton Protopopov
@ 2025-09-18 15:02 ` Alexei Starovoitov
2025-09-18 16:27 ` Anton Protopopov
0 siblings, 1 reply; 6+ messages in thread
From: Alexei Starovoitov @ 2025-09-18 15:02 UTC (permalink / raw)
To: Anton Protopopov; +Cc: bpf, Puranjay Mohan
On Thu, Sep 18, 2025 at 2:30 AM Anton Protopopov
<a.s.protopopov@gmail.com> wrote:
>
> The progs/stream.c BPF program now uses arena helpers, so it includes
> bpf_arena_common.h, which conflicts with the declarations generated
> in vmlinux.h. This leads to the following build errors with the recent
> LLVM:
>
> In file included from progs/stream.c:8:
> .../tools/testing/selftests/bpf/bpf_arena_common.h:47:15: error: conflicting types for 'bpf_arena_alloc_pages'
> 47 | void __arena* bpf_arena_alloc_pages(void *map, void __arena *addr, __u32 page_cnt,
> | ^
> .../tools/testing/selftests/bpf/tools/include/vmlinux.h:229284:14: note: previous declaration is here
> 229284 | extern void *bpf_arena_alloc_pages(void *p__map, void *addr__ign, u32 page_cnt, int node_id, u64 flags) __weak __ksym;
> | ^
>
> ... etc
I suspect you're using old pahole.
New one can transfer __arena tags into vmlinux.h
pw-bot: cr
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: fix build with new LLVM
2025-09-18 16:27 ` Anton Protopopov
@ 2025-09-18 16:26 ` Alexei Starovoitov
2025-09-19 22:29 ` Andrii Nakryiko
2025-10-20 9:06 ` Anton Protopopov
0 siblings, 2 replies; 6+ messages in thread
From: Alexei Starovoitov @ 2025-09-18 16:26 UTC (permalink / raw)
To: Anton Protopopov; +Cc: bpf, Puranjay Mohan
On Thu, Sep 18, 2025 at 9:21 AM Anton Protopopov
<a.s.protopopov@gmail.com> wrote:
>
> On 25/09/18 08:02AM, Alexei Starovoitov wrote:
> > On Thu, Sep 18, 2025 at 2:30 AM Anton Protopopov
> > <a.s.protopopov@gmail.com> wrote:
> > >
> > > The progs/stream.c BPF program now uses arena helpers, so it includes
> > > bpf_arena_common.h, which conflicts with the declarations generated
> > > in vmlinux.h. This leads to the following build errors with the recent
> > > LLVM:
> > >
> > > In file included from progs/stream.c:8:
> > > .../tools/testing/selftests/bpf/bpf_arena_common.h:47:15: error: conflicting types for 'bpf_arena_alloc_pages'
> > > 47 | void __arena* bpf_arena_alloc_pages(void *map, void __arena *addr, __u32 page_cnt,
> > > | ^
> > > .../tools/testing/selftests/bpf/tools/include/vmlinux.h:229284:14: note: previous declaration is here
> > > 229284 | extern void *bpf_arena_alloc_pages(void *p__map, void *addr__ign, u32 page_cnt, int node_id, u64 flags) __weak __ksym;
> > > | ^
> > >
> > > ... etc
> >
> > I suspect you're using old pahole.
> > New one can transfer __arena tags into vmlinux.h
>
> Ok, TIL about CONFIG_PAHOLE_VERSION (before I've sent the patch,
> I've updated the pahole, re-built the kernel, but didn't do `make
> oldconfig` after updating pahole.)
Yeah. It's a footgun that few people are aware of :(
I was bitten by it too.
We have a small section about pahole in bpf_devel_QA.rst.
We should probably expand it and list the common issues and how to fix them.
Every week somebody sends a patch due to old pahole :(
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: fix build with new LLVM
2025-09-18 15:02 ` Alexei Starovoitov
@ 2025-09-18 16:27 ` Anton Protopopov
2025-09-18 16:26 ` Alexei Starovoitov
0 siblings, 1 reply; 6+ messages in thread
From: Anton Protopopov @ 2025-09-18 16:27 UTC (permalink / raw)
To: Alexei Starovoitov; +Cc: bpf, Puranjay Mohan
On 25/09/18 08:02AM, Alexei Starovoitov wrote:
> On Thu, Sep 18, 2025 at 2:30 AM Anton Protopopov
> <a.s.protopopov@gmail.com> wrote:
> >
> > The progs/stream.c BPF program now uses arena helpers, so it includes
> > bpf_arena_common.h, which conflicts with the declarations generated
> > in vmlinux.h. This leads to the following build errors with the recent
> > LLVM:
> >
> > In file included from progs/stream.c:8:
> > .../tools/testing/selftests/bpf/bpf_arena_common.h:47:15: error: conflicting types for 'bpf_arena_alloc_pages'
> > 47 | void __arena* bpf_arena_alloc_pages(void *map, void __arena *addr, __u32 page_cnt,
> > | ^
> > .../tools/testing/selftests/bpf/tools/include/vmlinux.h:229284:14: note: previous declaration is here
> > 229284 | extern void *bpf_arena_alloc_pages(void *p__map, void *addr__ign, u32 page_cnt, int node_id, u64 flags) __weak __ksym;
> > | ^
> >
> > ... etc
>
> I suspect you're using old pahole.
> New one can transfer __arena tags into vmlinux.h
Ok, TIL about CONFIG_PAHOLE_VERSION (before I've sent the patch,
I've updated the pahole, re-built the kernel, but didn't do `make
oldconfig` after updating pahole.)
> pw-bot: cr
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: fix build with new LLVM
2025-09-18 16:26 ` Alexei Starovoitov
@ 2025-09-19 22:29 ` Andrii Nakryiko
2025-10-20 9:06 ` Anton Protopopov
1 sibling, 0 replies; 6+ messages in thread
From: Andrii Nakryiko @ 2025-09-19 22:29 UTC (permalink / raw)
To: Alexei Starovoitov; +Cc: Anton Protopopov, bpf, Puranjay Mohan
On Thu, Sep 18, 2025 at 9:29 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Thu, Sep 18, 2025 at 9:21 AM Anton Protopopov
> <a.s.protopopov@gmail.com> wrote:
> >
> > On 25/09/18 08:02AM, Alexei Starovoitov wrote:
> > > On Thu, Sep 18, 2025 at 2:30 AM Anton Protopopov
> > > <a.s.protopopov@gmail.com> wrote:
> > > >
> > > > The progs/stream.c BPF program now uses arena helpers, so it includes
> > > > bpf_arena_common.h, which conflicts with the declarations generated
> > > > in vmlinux.h. This leads to the following build errors with the recent
> > > > LLVM:
> > > >
> > > > In file included from progs/stream.c:8:
> > > > .../tools/testing/selftests/bpf/bpf_arena_common.h:47:15: error: conflicting types for 'bpf_arena_alloc_pages'
> > > > 47 | void __arena* bpf_arena_alloc_pages(void *map, void __arena *addr, __u32 page_cnt,
> > > > | ^
> > > > .../tools/testing/selftests/bpf/tools/include/vmlinux.h:229284:14: note: previous declaration is here
> > > > 229284 | extern void *bpf_arena_alloc_pages(void *p__map, void *addr__ign, u32 page_cnt, int node_id, u64 flags) __weak __ksym;
> > > > | ^
> > > >
> > > > ... etc
> > >
> > > I suspect you're using old pahole.
> > > New one can transfer __arena tags into vmlinux.h
> >
> > Ok, TIL about CONFIG_PAHOLE_VERSION (before I've sent the patch,
> > I've updated the pahole, re-built the kernel, but didn't do `make
> > oldconfig` after updating pahole.)
>
> Yeah. It's a footgun that few people are aware of :(
> I was bitten by it too.
> We have a small section about pahole in bpf_devel_QA.rst.
> We should probably expand it and list the common issues and how to fix them.
> Every week somebody sends a patch due to old pahole :(
>
There is some magical CC_VERSION_TEXT that is supposed to fix a
similar problem for the compiler version. I didn't completely
understand how it's done, but perhaps we can use the same idea to
update pahole version when it changes?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: fix build with new LLVM
2025-09-18 16:26 ` Alexei Starovoitov
2025-09-19 22:29 ` Andrii Nakryiko
@ 2025-10-20 9:06 ` Anton Protopopov
1 sibling, 0 replies; 6+ messages in thread
From: Anton Protopopov @ 2025-10-20 9:06 UTC (permalink / raw)
To: Alexei Starovoitov; +Cc: bpf, Puranjay Mohan
On 25/09/18 09:26AM, Alexei Starovoitov wrote:
> On Thu, Sep 18, 2025 at 9:21 AM Anton Protopopov
> <a.s.protopopov@gmail.com> wrote:
> >
> > On 25/09/18 08:02AM, Alexei Starovoitov wrote:
> > > On Thu, Sep 18, 2025 at 2:30 AM Anton Protopopov
> > > <a.s.protopopov@gmail.com> wrote:
> > > >
> > > > The progs/stream.c BPF program now uses arena helpers, so it includes
> > > > bpf_arena_common.h, which conflicts with the declarations generated
> > > > in vmlinux.h. This leads to the following build errors with the recent
> > > > LLVM:
> > > >
> > > > In file included from progs/stream.c:8:
> > > > .../tools/testing/selftests/bpf/bpf_arena_common.h:47:15: error: conflicting types for 'bpf_arena_alloc_pages'
> > > > 47 | void __arena* bpf_arena_alloc_pages(void *map, void __arena *addr, __u32 page_cnt,
> > > > | ^
> > > > .../tools/testing/selftests/bpf/tools/include/vmlinux.h:229284:14: note: previous declaration is here
> > > > 229284 | extern void *bpf_arena_alloc_pages(void *p__map, void *addr__ign, u32 page_cnt, int node_id, u64 flags) __weak __ksym;
> > > > | ^
> > > >
> > > > ... etc
> > >
> > > I suspect you're using old pahole.
> > > New one can transfer __arena tags into vmlinux.h
> >
> > Ok, TIL about CONFIG_PAHOLE_VERSION (before I've sent the patch,
> > I've updated the pahole, re-built the kernel, but didn't do `make
> > oldconfig` after updating pahole.)
>
> Yeah. It's a footgun that few people are aware of :(
> I was bitten by it too.
> We have a small section about pahole in bpf_devel_QA.rst.
> We should probably expand it and list the common issues and how to fix them.
> Every week somebody sends a patch due to old pahole :(
And today I also learned about the "next" branch of the pahole repo.
The "master" branch was too old to generate kfunc header for a kfunc
compiled with a .cold part (namely, bpf_dynptr_slice).
As the "old pahole" thing happens to so many people, maybe there is
a way to in-source it into kernel?..
^ permalink raw reply [flat|nested] 6+ messages in thread
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2025-09-18 9:36 [PATCH bpf-next] selftests/bpf: fix build with new LLVM Anton Protopopov
2025-09-18 15:02 ` Alexei Starovoitov
2025-09-18 16:27 ` Anton Protopopov
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