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Date:   Fri, 13 Jan 2023 12:31:09 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Tony Lindgren <tony@...mide.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Frederic Weisbecker <frederic@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] cpuidle, sched: Remove instrumentation from
 TIF_{POLLING_NRFLAG,NEED_RESCHED}

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     e4df1511e1f4bcaa0d590aa7bbffe8bbbd6dfb49
Gitweb:        https://git.kernel.org/tip/e4df1511e1f4bcaa0d590aa7bbffe8bbbd6dfb49
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Thu, 12 Jan 2023 20:43:41 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Fri, 13 Jan 2023 11:48:16 +01:00

cpuidle, sched: Remove instrumentation from TIF_{POLLING_NRFLAG,NEED_RESCHED}

objtool pointed out that various idle-TIF management methods
have instrumentation:

  vmlinux.o: warning: objtool: mwait_idle+0x5: call to current_set_polling_and_test() leaves .noinstr.text section
  vmlinux.o: warning: objtool: acpi_processor_ffh_cstate_enter+0xc5: call to current_set_polling_and_test() leaves .noinstr.text section
  vmlinux.o: warning: objtool: cpu_idle_poll.isra.0+0x73: call to test_ti_thread_flag() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle+0xbc: call to current_set_polling_and_test() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle_irq+0xea: call to current_set_polling_and_test() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle_s2idle+0xb4: call to current_set_polling_and_test() leaves .noinstr.text section

  vmlinux.o: warning: objtool: intel_idle+0xa6: call to current_clr_polling() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle_irq+0xbf: call to current_clr_polling() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle_s2idle+0xa1: call to current_clr_polling() leaves .noinstr.text section

  vmlinux.o: warning: objtool: mwait_idle+0xe: call to __current_set_polling() leaves .noinstr.text section
  vmlinux.o: warning: objtool: acpi_processor_ffh_cstate_enter+0xc5: call to __current_set_polling() leaves .noinstr.text section
  vmlinux.o: warning: objtool: cpu_idle_poll.isra.0+0x73: call to test_ti_thread_flag() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle+0xbc: call to __current_set_polling() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle_irq+0xea: call to __current_set_polling() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle_s2idle+0xb4: call to __current_set_polling() leaves .noinstr.text section

  vmlinux.o: warning: objtool: cpu_idle_poll.isra.0+0x73: call to test_ti_thread_flag() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle_s2idle+0x73: call to test_ti_thread_flag.constprop.0() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle_irq+0x91: call to test_ti_thread_flag.constprop.0() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle+0x78: call to test_ti_thread_flag.constprop.0() leaves .noinstr.text section
  vmlinux.o: warning: objtool: acpi_safe_halt+0xf: call to test_ti_thread_flag.constprop.0() leaves .noinstr.text section

Remove the instrumentation, because these methods are used in low-level
cpuidle code moving between states, that should not be instrumented.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Tested-by: Tony Lindgren <tony@...mide.com>
Tested-by: Ulf Hansson <ulf.hansson@...aro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Acked-by: Frederic Weisbecker <frederic@...nel.org>
Link: https://lore.kernel.org/r/20230112195540.988741683@infradead.org
---
 include/linux/sched/idle.h  | 40 +++++++++++++++++++++++++++---------
 include/linux/thread_info.h | 18 +++++++++++++++-
 2 files changed, 47 insertions(+), 11 deletions(-)

diff --git a/include/linux/sched/idle.h b/include/linux/sched/idle.h
index d73d314..478084f 100644
--- a/include/linux/sched/idle.h
+++ b/include/linux/sched/idle.h
@@ -23,12 +23,37 @@ static inline void wake_up_if_idle(int cpu) { }
  */
 #ifdef TIF_POLLING_NRFLAG
 
-static inline void __current_set_polling(void)
+#ifdef _ASM_GENERIC_BITOPS_INSTRUMENTED_ATOMIC_H
+
+static __always_inline void __current_set_polling(void)
 {
-	set_thread_flag(TIF_POLLING_NRFLAG);
+	arch_set_bit(TIF_POLLING_NRFLAG,
+		     (unsigned long *)(&current_thread_info()->flags));
 }
 
-static inline bool __must_check current_set_polling_and_test(void)
+static __always_inline void __current_clr_polling(void)
+{
+	arch_clear_bit(TIF_POLLING_NRFLAG,
+		       (unsigned long *)(&current_thread_info()->flags));
+}
+
+#else
+
+static __always_inline void __current_set_polling(void)
+{
+	set_bit(TIF_POLLING_NRFLAG,
+		(unsigned long *)(&current_thread_info()->flags));
+}
+
+static __always_inline void __current_clr_polling(void)
+{
+	clear_bit(TIF_POLLING_NRFLAG,
+		  (unsigned long *)(&current_thread_info()->flags));
+}
+
+#endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_ATOMIC_H */
+
+static __always_inline bool __must_check current_set_polling_and_test(void)
 {
 	__current_set_polling();
 
@@ -41,12 +66,7 @@ static inline bool __must_check current_set_polling_and_test(void)
 	return unlikely(tif_need_resched());
 }
 
-static inline void __current_clr_polling(void)
-{
-	clear_thread_flag(TIF_POLLING_NRFLAG);
-}
-
-static inline bool __must_check current_clr_polling_and_test(void)
+static __always_inline bool __must_check current_clr_polling_and_test(void)
 {
 	__current_clr_polling();
 
@@ -73,7 +93,7 @@ static inline bool __must_check current_clr_polling_and_test(void)
 }
 #endif
 
-static inline void current_clr_polling(void)
+static __always_inline void current_clr_polling(void)
 {
 	__current_clr_polling();
 
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 9f392ec..c026468 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -177,7 +177,23 @@ static __always_inline unsigned long read_ti_thread_flags(struct thread_info *ti
 	clear_ti_thread_flag(task_thread_info(t), TIF_##fl)
 #endif /* !CONFIG_GENERIC_ENTRY */
 
-#define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED)
+#ifdef _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H
+
+static __always_inline bool tif_need_resched(void)
+{
+	return arch_test_bit(TIF_NEED_RESCHED,
+			     (unsigned long *)(&current_thread_info()->flags));
+}
+
+#else
+
+static __always_inline bool tif_need_resched(void)
+{
+	return test_bit(TIF_NEED_RESCHED,
+			(unsigned long *)(&current_thread_info()->flags));
+}
+
+#endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H */
 
 #ifndef CONFIG_HAVE_ARCH_WITHIN_STACK_FRAMES
 static inline int arch_within_stack_frames(const void * const stack,

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