From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Olsa <olsajiri@gmail.com>
Cc: Chen Hu <hu1.chen@intel.com>,
jpoimboe@kernel.org, memxor@gmail.com, bpf@vger.kernel.org,
Pengfei Xu <pengfei.xu@intel.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH bpf v2] selftests/bpf: Fix "missing ENDBR" BUG for destructor kfunc
Date: Tue, 22 Nov 2022 15:14:26 +0100 [thread overview]
Message-ID: <Y3zZQpHNQ8cRjKQY@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <Y3zTF0CjQFt/dR2M@krava>
On Tue, Nov 22, 2022 at 02:48:07PM +0100, Jiri Olsa wrote:
> On Mon, Nov 21, 2022 at 11:32:43PM -0800, Chen Hu wrote:
> > With CONFIG_X86_KERNEL_IBT enabled, the test_verifier triggers the
> > following BUG:
> >
> > traps: Missing ENDBR: bpf_kfunc_call_test_release+0x0/0x30
> > ------------[ cut here ]------------
> > kernel BUG at arch/x86/kernel/traps.c:254!
> > invalid opcode: 0000 [#1] PREEMPT SMP
> > <TASK>
> > asm_exc_control_protection+0x26/0x50
> > RIP: 0010:bpf_kfunc_call_test_release+0x0/0x30
> > Code: 00 48 c7 c7 18 f2 e1 b4 e8 0d ca 8c ff 48 c7 c0 00 f2 e1 b4 c3
> > 0f 1f 44 00 00 66 0f 1f 00 0f 1f 44 00 00 0f 0b 31 c0 c3 66 90
> > <66> 0f 1f 00 0f 1f 44 00 00 48 85 ff 74 13 4c 8d 47 18 b8 ff ff ff
> > bpf_map_free_kptrs+0x2e/0x70
> > array_map_free+0x57/0x140
> > process_one_work+0x194/0x3a0
> > worker_thread+0x54/0x3a0
> > ? rescuer_thread+0x390/0x390
> > kthread+0xe9/0x110
> > ? kthread_complete_and_exit+0x20/0x20
> >
> > This is because there are no compile-time references to the destructor
> > kfuncs, bpf_kfunc_call_test_release() for example. So objtool marked
> > them sealable and ENDBR in the functions were sealed (converted to NOP)
> > by apply_ibt_endbr().
If there is no compile time reference to it, what stops an LTO linker
from throwing it out in the first place?
next prev parent reply other threads:[~2022-11-22 14:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-22 7:32 [PATCH bpf v2] selftests/bpf: Fix "missing ENDBR" BUG for destructor kfunc Chen Hu
2022-11-22 13:48 ` Jiri Olsa
2022-11-22 14:14 ` Peter Zijlstra [this message]
2022-11-25 13:44 ` Chen, Hu1
2022-11-27 22:04 ` Jiri Olsa
2022-11-27 22:13 ` Alexei Starovoitov
2022-11-25 13:28 ` Chen, Hu1
2022-11-27 21:58 ` Jiri Olsa
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