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From: Thomas Gleixner <tglx@linutronix.de>
To: Josh Poimboeuf <jpoimboe@kernel.org>, x86@kernel.org
Cc: linux-kernel@vger.kernel.org,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] tracing: Disable branch profiling in noinstr code
Date: Fri, 21 Mar 2025 17:51:50 +0100	[thread overview]
Message-ID: <871puq2uop.ffs@tglx> (raw)
In-Reply-To: <52a664ec9e14ef53c39c3d4fa400c2f1d29348c0.1742537096.git.jpoimboe@kernel.org>

On Thu, Mar 20 2025 at 23:05, Josh Poimboeuf wrote:

> CONFIG_TRACE_BRANCH_PROFILING inserts a call to ftrace_likely_update()
> for each use of likely() or unlikely().  If the caller is noinstr, that
> breaks the noinstr rules.
>
> Disable branch profiling for files which have noinstr functions.  Fixes
> many warnings like the following:
>
>   vmlinux.o: warning: objtool: do_syscall_64+0x40: call to ftrace_likely_update() leaves .noinstr.text section
>   vmlinux.o: warning: objtool: __rdgsbase_inactive+0x33: call to ftrace_likely_update() leaves .noinstr.text section
>   vmlinux.o: warning: objtool: handle_bug.isra.0+0x198: call to ftrace_likely_update() leaves .noinstr.text section
>   ...

Acked-by: Thomas Gleixner <tglx@linutronix.de>

Thanks for fixing this!

Though the real fix would be to rip out this likely/unlikely tracer
hackery all together.

        tglx

  reply	other threads:[~2025-03-21 16:51 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-03-21  6:05 [PATCH] tracing: Disable branch profiling in noinstr code Josh Poimboeuf
2025-03-21 16:51 ` Thomas Gleixner [this message]
2025-03-21 17:12   ` Steven Rostedt
2025-03-21 17:21     ` Josh Poimboeuf
2025-03-21 18:28       ` Steven Rostedt
2025-03-21 18:53         ` Josh Poimboeuf
2025-03-21 20:28     ` Thomas Gleixner

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