From: Peter Zijlstra <peterz@infradead.org>
To: Sasha Levin <sashal@kernel.org>
Cc: linux-kernel@vger.kernel.org, Chuck Wolber <chuck@wolber.net>,
Frederic Weisbecker <frederic@kernel.org>,
Marco Elver <elver@google.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Thomas Gleixner <tglx@kernel.org>
Subject: Re: [RFC PATCH 05/20] context_tracking: Always inline the empty stubs called from noinstr code
Date: Wed, 28 Oct 2026 14:52:51 +0100 [thread overview]
Message-ID: <20261028135251.GS2668564@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20261028120034.871983-6-sashal@kernel.org>
On Wed, Oct 28, 2026 at 07:59:29AM -0400, Sasha Levin wrote:
> The !CONFIG_CONTEXT_TRACKING_USER versions of user_enter_irqoff() and
> user_exit_irqoff(), and the !CONFIG_CONTEXT_TRACKING_IDLE versions of
> ct_idle_enter() and ct_idle_exit(), are plain static inline functions,
> while their real counterparts are __always_inline (user_*_irqoff()) or
> noinstr (ct_idle_*()) functions. They are called from noinstr code, so
> when they aren't inlined that's a call leaving the noinstr section. This
> happens with code coverage instrumentation, which makes the compiler
> refuse to inline an instrumented function into a noinstr one:
>
> vmlinux.o: warning: objtool: do_syscall_64+0x81: call to user_exit_irqoff() leaves .noinstr.text section
>
> Make the stubs __always_inline as well.
Ah yes, nothing beats adding instrumentation to empty functions :-)
next prev parent reply other threads:[~2026-10-28 13:52 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-28 11:59 [RFC PATCH 00/20] Unify code coverage and add Clang source-based coverage with MC/DC Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 01/20] coverage: move gcov and kcov under kernel/coverage/ Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 02/20] kbuild: unify static coverage instrumentation as COVERAGE_PROFILE Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 03/20] coverage: add a common debugfs interface Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 04/20] compiler_types.h: Don't instrument __always_inline functions for coverage Sasha Levin
2026-10-28 13:51 ` Peter Zijlstra
2026-10-28 14:01 ` Peter Zijlstra
2026-10-28 16:45 ` Sasha Levin
2026-10-29 5:49 ` Chuck Wolber
2026-10-28 11:59 ` [RFC PATCH 05/20] context_tracking: Always inline the empty stubs called from noinstr code Sasha Levin
2026-10-28 13:52 ` Peter Zijlstra [this message]
2026-10-28 11:59 ` [RFC PATCH 06/20] lockdep: " Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 07/20] perf: Always inline the empty perf_lopwr_cb() stub Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 08/20] rseq: Always inline the empty rseq_note_user_irq_entry() stub Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 09/20] x86: Always inline empty stubs called from noinstr code Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 10/20] x86/sev: Use non-instrumented bitops in the GHCB accessors Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 11/20] objtool: Detect code coverage instrumentation in noinstr code Sasha Levin
2026-10-28 14:11 ` Peter Zijlstra
2026-10-28 16:45 ` Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 12/20] x86/sev: Stop excluding noinstr.o from code coverage Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 13/20] x86/entry: Stop excluding the entry code from KCOV Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 14/20] coverage: add Clang's source-based code coverage Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 15/20] x86: Enable " Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 16/20] coverage: add MC/DC measurement Sasha Levin
2026-10-28 19:14 ` Nathan Chancellor
2026-10-28 20:39 ` Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 17/20] gcov: fix gcov_info_add() merge semantics for IOR counters Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 18/20] kconfig: add CC_HAS_CONDITION_COVERAGE for MC/DC support detection Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 19/20] gcov: add MC/DC condition coverage support Sasha Levin
2026-10-28 11:59 ` [RFC PATCH 20/20] Documentation: dev-tools: document the common code coverage interface Sasha Levin
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