From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "Ihor Solodrai" <ihor.solodrai@linux.dev>,
<patchwork-bot+netdevbpf@kernel.org>
Cc: <bpf@vger.kernel.org>, <daniel@iogearbox.net>,
<andrii@kernel.org>, <eddyz87@gmail.com>, <memxor@gmail.com>,
"Emil Tsalapatis" <emil@etsalapatis.com>
Subject: Re: [PATCH bpf-next v2 00/17] bpf: Indirect calls of bpf subprogs (callx)
Date: Tue, 29 Sep 2026 06:04:47 +0000 [thread overview]
Message-ID: <DLRKNUWD51KM.3URQDVOWL0BRY@gmail.com> (raw)
In-Reply-To: <a25b9150-55ba-41ef-8de9-0067b4576278@linux.dev>
On Mon, Sep 28, 2026 at 04:13 PM Ihor Solodrai <ihor.solodrai@linux.dev> wrote:
> We're testing clang 21->22 bump on BPF CI, and something is broken
> when compiling callx selftests:
>
> 2026-09-28T22:12:12.4226025Z error: Undefined temporary symbol
> .Lswitch.table.call_by_switch
That's a bug in llvm 22. Not related to callx.
With -mcpu=v4 BPFAsmPrinter::doFinalization() is supposed to remove
private arrays of blockaddress that were converted to gotox jump tables,
but it removes all private const arrays of pointers.
clang turns the switch in call_by_switch() into such array of
pointers to functions.
Yonghong fixed it in llvm 23:
commit 9fc458a1d95b ("[BPF] Fix erroneous removal of non-jump-table globals")
It landed after 22.1.8, so no release of 22 has it.
> What's the requirements for callx? Does it need bleeding edge clang?
> If so, let's explicitly skip relevant selftests for clang < N?
No. clang generates callx for years. clang 21 is fine and 22 is fine
with v2 and v3.
I'd bump CI to clang 23.
A bunch of other tests require __clang_major__ >= 23 already.
next prev parent reply other threads:[~2026-09-29 6:04 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-24 3:10 [PATCH bpf-next v2 00/17] bpf: Indirect calls of bpf subprogs (callx) Alexei Starovoitov
2026-09-24 3:10 ` [PATCH bpf-next v2 01/17] bpf: Fix infinite loop in check_max_stack_depth() Alexei Starovoitov
2026-09-24 3:10 ` [PATCH bpf-next v2 02/17] selftests/bpf: Test recursion through a global function and a callback Alexei Starovoitov
2026-09-24 3:10 ` [PATCH bpf-next v2 03/17] bpf: Keep functions with address taken when removing dead code Alexei Starovoitov
2026-09-24 3:10 ` [PATCH bpf-next v2 04/17] bpf: Prepare static analysis passes for callx instruction Alexei Starovoitov
2026-09-24 3:56 ` bot+bpf-ci
2026-09-24 4:18 ` Eduard Zingerman
2026-09-24 3:10 ` [PATCH bpf-next v2 05/17] bpf: Add callx instruction to call bpf subprogs indirectly Alexei Starovoitov
2026-09-24 3:28 ` sashiko-bot
2026-09-24 3:10 ` [PATCH bpf-next v2 06/17] bpf: Add callx calls to the call graph Alexei Starovoitov
2026-09-24 3:26 ` sashiko-bot
2026-09-24 3:56 ` bot+bpf-ci
2026-09-24 5:00 ` Eduard Zingerman
2026-09-24 3:10 ` [PATCH bpf-next v2 07/17] bpf, x86: Add JIT support for callx Alexei Starovoitov
2026-09-24 5:33 ` Eduard Zingerman
2026-09-24 3:10 ` [PATCH bpf-next v2 08/17] bpf, arm64: " Alexei Starovoitov
2026-09-24 3:10 ` [PATCH bpf-next v2 09/17] bpf: Discover subprogs described by func_info Alexei Starovoitov
2026-09-24 5:42 ` Eduard Zingerman
2026-09-24 3:10 ` [PATCH bpf-next v2 10/17] bpf: Recognize pointers to functions in read-only maps Alexei Starovoitov
2026-09-24 3:10 ` [PATCH bpf-next v2 11/17] libbpf: Support pointers to static functions in data when linking Alexei Starovoitov
2026-09-24 3:10 ` [PATCH bpf-next v2 12/17] libbpf: Resolve pointers to functions in read-only data Alexei Starovoitov
2026-09-24 3:27 ` sashiko-bot
2026-09-24 3:10 ` [PATCH bpf-next v2 13/17] libbpf: Treat .data.rel.ro as " Alexei Starovoitov
2026-09-24 3:10 ` [PATCH bpf-next v2 14/17] libbpf: Support pointers to functions in read-only data in light skeleton Alexei Starovoitov
2026-09-24 3:10 ` [PATCH bpf-next v2 15/17] selftests/bpf: Add tests for callx Alexei Starovoitov
2026-09-24 3:56 ` bot+bpf-ci
2026-09-24 3:10 ` [PATCH bpf-next v2 16/17] selftests/bpf: Add tests for callx through pointers in read-only data Alexei Starovoitov
2026-09-24 3:10 ` [PATCH bpf-next v2 17/17] bpf, docs: Document callx instruction Alexei Starovoitov
2026-09-24 5:50 ` [PATCH bpf-next v2 00/17] bpf: Indirect calls of bpf subprogs (callx) patchwork-bot+netdevbpf
2026-09-24 5:55 ` Eduard Zingerman
2026-09-24 6:00 ` Alexei Starovoitov
2026-09-24 17:50 ` Ihor Solodrai
2026-09-24 18:09 ` Alexei Starovoitov
2026-09-28 23:13 ` Ihor Solodrai
2026-09-29 6:04 ` Alexei Starovoitov [this message]
2026-09-29 16:40 ` Ihor Solodrai
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