From: Dropify <d.dropify@gmail.com>
To: zhengyejian1@huawei.com
Cc: bpf@vger.kernel.org, jpoimboe@kernel.org,
linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org,
linux-trace-kernel@vger.kernel.org, mark.rutland@arm.com,
mathieu.desnoyers@efficios.com, mcgrof@kernel.org,
mhiramat@kernel.org, peterz@infradead.org, rostedt@goodmis.org
Subject: Re: [RFC PATCH] ftrace: Skip __fentry__ location of overridden weak functions
Date: Wed, 13 Nov 2024 13:02:43 +0530 [thread overview]
Message-ID: <8acdd32a-1702-4434-8d79-2e73ded36d2a@gmail.com> (raw)
In-Reply-To: <20240607115211.734845-1-zhengyejian1@huawei.com>
Wondering where are we with this issue?
I am experiencing an issue where in a fentry/kfunc bpf probe attached to
a function doesn't fire. I have only experienced this behavior on Debian
kernels with `CONFIG_X86_KERNEL_IBT` enabled.
Because of weak symbols being removed from kallsyms,
kallsyms_lookup_size_offset() returns the symbol offset for the function
"acct_process()" more than the actual size. And the function body now
contains two __fentry__ locations.
Depending on where binary search lands up first, correct (acct_process +
4) or incorrect (acct_process + 260) location is returned.
Thanks,
Dropify
prev parent reply other threads:[~2024-11-13 7:32 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-07 11:52 [RFC PATCH] ftrace: Skip __fentry__ location of overridden weak functions Zheng Yejian
2024-06-07 15:02 ` Peter Zijlstra
2024-06-07 15:39 ` Steven Rostedt
2024-06-11 1:56 ` Zheng Yejian
2024-06-11 9:21 ` Peter Zijlstra
2024-06-11 9:36 ` Zheng Yejian
2024-11-13 7:32 ` Dropify [this message]
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