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From: Peter Zijlstra <peterz@infradead.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Menglong Dong <menglong8.dong@gmail.com>,
	Jiri Olsa <jolsa@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	Kees Cook <kees@kernel.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	Mike Rapoport <rppt@kernel.org>,
	Andy Lutomirski <luto@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>, bpf <bpf@vger.kernel.org>
Subject: Re: [PATCH] x86/ibt: make is_endbr() notrace
Date: Mon, 22 Sep 2025 08:36:16 +0200	[thread overview]
Message-ID: <20250922063616.GN3245006@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <CAADnVQLP6-s_dtGpEcnFaVJfDW12rTOS2qk5k0Fyvn=4Gn7gBw@mail.gmail.com>

On Thu, Sep 18, 2025 at 10:53:51AM -0700, Alexei Starovoitov wrote:

> > notrace don't help with kprobes in general, only with __fentry__ sites.
> 
> Are you sure ? Last time I checked "notrace" prevents kprobing
> anywhere in that function.

#define notrace                 __attribute__((__no_instrument_function__))

AFAICT that only inhibits the compiler from generating __fentry__ calls.

There is NOKPROBE_SYMBOL() to explicitly exclude kprobes from a symbol.

And we have noinstr, which along with a gazillion code-gen attributes
puts things in a .noinstr.text section and that section is also excluded
from kprobe placement.

  parent reply	other threads:[~2025-09-22  6:36 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-18 12:09 Menglong Dong
2025-09-18 13:05 ` Peter Zijlstra
2025-09-18 13:32   ` Menglong Dong
2025-09-18 16:02     ` Alexei Starovoitov
2025-09-18 16:59       ` Peter Zijlstra
2025-09-18 17:53         ` Alexei Starovoitov
2025-09-19  1:13           ` Menglong Dong
2025-09-22  6:52             ` Peter Zijlstra
2025-09-22  7:13               ` menglong.dong
2025-09-22  7:19                 ` Peter Zijlstra
2025-09-22  7:21                   ` Menglong Dong
2025-09-22  6:36           ` Peter Zijlstra [this message]
2025-09-18 16:56     ` Peter Zijlstra
2025-09-19 12:35       ` Masami Hiramatsu
2025-09-19  8:52 ` Masami Hiramatsu
2025-09-19  8:58   ` Menglong Dong
2025-09-19 12:32     ` Masami Hiramatsu
2025-09-19 11:57 ` [PATCH] tracing: fgraph: Protect return handler from recursion loop Masami Hiramatsu (Google)
2025-09-19 15:27   ` Steven Rostedt
2025-09-20  7:45     ` Jiri Olsa
2025-09-22  6:16       ` Masami Hiramatsu
2025-09-22 13:38         ` Jiri Olsa
2025-09-22 14:42           ` Steven Rostedt
2025-09-22 19:45           ` Jiri Olsa
2025-09-21  4:05     ` Masami Hiramatsu
2025-09-21 22:52       ` Steven Rostedt
2025-09-24 22:58         ` Masami Hiramatsu
2025-09-20 13:39   ` Menglong Dong
2025-09-21  4:06     ` Masami Hiramatsu
2025-09-21 23:00       ` Steven Rostedt
2025-09-24 22:59         ` Masami Hiramatsu
2025-09-22  5:19     ` Masami Hiramatsu

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