cpuidle, mwait: Make the mwait code noinstr clean

objtool found a few cases where this code called out into instrumented
code:

  vmlinux.o: warning: objtool: intel_idle_s2idle+0x6e: call to __monitor.constprop.0() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle_irq+0x8c: call to __monitor.constprop.0() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle+0x73: call to __monitor.constprop.0() leaves .noinstr.text section

  vmlinux.o: warning: objtool: mwait_idle+0x88: call to clflush() leaves .noinstr.text section

Fix it by marking the affected methods as __always_inline.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195541.050542952@infradead.org

arch/x86/include/asm/mwait.h

@@ -26,7 +26,7 @@
 #define TPAUSE_C01_STATE		1
 #define TPAUSE_C02_STATE		0
 
-static inline void __monitor(const void *eax, unsigned long ecx,
+static __always_inline void __monitor(const void *eax, unsigned long ecx,
 			     unsigned long edx)
 {
 	/* "monitor %eax, %ecx, %edx;" */
@@ -34,7 +34,7 @@ static inline void __monitor(const void *eax, unsigned long ecx,
 		     :: "a" (eax), "c" (ecx), "d"(edx));
 }
 
-static inline void __monitorx(const void *eax, unsigned long ecx,
+static __always_inline void __monitorx(const void *eax, unsigned long ecx,
 			      unsigned long edx)
 {
 	/* "monitorx %eax, %ecx, %edx;" */
@@ -42,7 +42,7 @@ static inline void __monitorx(const void *eax, unsigned long ecx,
 		     :: "a" (eax), "c" (ecx), "d"(edx));
 }
 
-static inline void __mwait(unsigned long eax, unsigned long ecx)
+static __always_inline void __mwait(unsigned long eax, unsigned long ecx)
 {
 	mds_idle_clear_cpu_buffers();
 
@@ -77,8 +77,8 @@ static inline void __mwait(unsigned long eax, unsigned long ecx)
  * EAX                     (logical) address to monitor
  * ECX                     #GP if not zero
  */
-static inline void __mwaitx(unsigned long eax, unsigned long ebx,
-			    unsigned long ecx)
+static __always_inline void __mwaitx(unsigned long eax, unsigned long ebx,
+				     unsigned long ecx)
 {
 	/* No MDS buffer clear as this is AMD/HYGON only */
 
@@ -87,7 +87,7 @@ static inline void __mwaitx(unsigned long eax, unsigned long ebx,
 		     :: "a" (eax), "b" (ebx), "c" (ecx));
 }
 
-static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
+static __always_inline void __sti_mwait(unsigned long eax, unsigned long ecx)
 {
 	mds_idle_clear_cpu_buffers();
 	/* "mwait %eax, %ecx;" */

arch/x86/include/asm/special_insns.h

@@ -196,7 +196,7 @@ static inline void load_gs_index(unsigned int selector)
 
 #endif /* CONFIG_PARAVIRT_XXL */
 
-static inline void clflush(volatile void *__p)
+static __always_inline void clflush(volatile void *__p)
 {
 	asm volatile("clflush %0" : "+m" (*(volatile char __force *)__p));
 }