[PATCH 12/15] x86: Remove !CONFIG_X86_TSC code

[Ingo Molnar <mingo@kernel.org>]

Now that the Kconfig space always enables CONFIG_X86_TSC (on x86),
remove !CONFIG_X86_TSC code.

We still keep the Kconfig option to catch any eventual code still
pending in maintainer or non-mainline trees, and it's also still
possible to disable TSC support runtime.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ahmed S . Darwish <darwi@linutronix.de>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: H . Peter Anvin <hpa@zytor.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250425084216.3913608-13-mingo@kernel.org
---
 arch/x86/include/asm/timex.h       |  3 +--
 arch/x86/include/asm/trace_clock.h |  8 --------
 arch/x86/include/asm/tsc.h         | 13 +------------
 arch/x86/kernel/Makefile           |  4 ++--
 arch/x86/kernel/i8253.c            |  2 +-
 arch/x86/kernel/tsc.c              | 13 -------------
 6 files changed, 5 insertions(+), 38 deletions(-)

diff --git a/arch/x86/include/asm/timex.h b/arch/x86/include/asm/timex.h
index 956e4145311b..6e57e3c0fdd2 100644
--- a/arch/x86/include/asm/timex.h
+++ b/arch/x86/include/asm/timex.h
@@ -7,8 +7,7 @@
 
 static inline unsigned long random_get_entropy(void)
 {
-	if (!IS_ENABLED(CONFIG_X86_TSC) &&
-	    !cpu_feature_enabled(X86_FEATURE_TSC))
+	if (!cpu_feature_enabled(X86_FEATURE_TSC))
 		return random_get_entropy_fallback();
 	return rdtsc();
 }
diff --git a/arch/x86/include/asm/trace_clock.h b/arch/x86/include/asm/trace_clock.h
index 7061a5650969..1efab284c32a 100644
--- a/arch/x86/include/asm/trace_clock.h
+++ b/arch/x86/include/asm/trace_clock.h
@@ -5,17 +5,9 @@
 #include <linux/compiler.h>
 #include <linux/types.h>
 
-#ifdef CONFIG_X86_TSC
-
 extern u64 notrace trace_clock_x86_tsc(void);
 
 # define ARCH_TRACE_CLOCKS \
 	{ trace_clock_x86_tsc,	"x86-tsc",	.in_ns = 0 },
 
-#else /* !CONFIG_X86_TSC */
-
-#define ARCH_TRACE_CLOCKS
-
-#endif
-
 #endif  /* _ASM_X86_TRACE_CLOCK_H */
diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index 4f7f09f50552..4d2d2f21ff06 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -76,8 +76,7 @@ extern void disable_TSC(void);
 
 static inline cycles_t get_cycles(void)
 {
-	if (!IS_ENABLED(CONFIG_X86_TSC) &&
-	    !cpu_feature_enabled(X86_FEATURE_TSC))
+	if (!cpu_feature_enabled(X86_FEATURE_TSC))
 		return 0;
 	return rdtsc();
 }
@@ -94,25 +93,15 @@ extern unsigned long native_calibrate_tsc(void);
 extern unsigned long long native_sched_clock_from_tsc(u64 tsc);
 
 extern int tsc_clocksource_reliable;
-#ifdef CONFIG_X86_TSC
 extern bool tsc_async_resets;
-#else
-# define tsc_async_resets	false
-#endif
 
 /*
  * Boot-time check whether the TSCs are synchronized across
  * all CPUs/cores:
  */
-#ifdef CONFIG_X86_TSC
 extern bool tsc_store_and_check_tsc_adjust(bool bootcpu);
 extern void tsc_verify_tsc_adjust(bool resume);
 extern void check_tsc_sync_target(void);
-#else
-static inline bool tsc_store_and_check_tsc_adjust(bool bootcpu) { return false; }
-static inline void tsc_verify_tsc_adjust(bool resume) { }
-static inline void check_tsc_sync_target(void) { }
-#endif
 
 extern int notsc_setup(char *);
 extern void tsc_save_sched_clock_state(void);
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index bc184dd38d99..19ebb67df142 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -94,7 +94,7 @@ apm-y				:= apm_32.o
 obj-$(CONFIG_APM)		+= apm.o
 obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_SMP)		+= smpboot.o
-obj-$(CONFIG_X86_TSC)		+= tsc_sync.o
+obj-y				+= tsc_sync.o
 obj-$(CONFIG_SMP)		+= setup_percpu.o
 obj-$(CONFIG_X86_MPPARSE)	+= mpparse.o
 obj-y				+= apic/
@@ -103,7 +103,7 @@ obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace_$(BITS).o
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
 obj-$(CONFIG_FTRACE_SYSCALLS)	+= ftrace.o
-obj-$(CONFIG_X86_TSC)		+= trace_clock.o
+obj-y				+= trace_clock.o
 obj-$(CONFIG_TRACING)		+= trace.o
 obj-$(CONFIG_RETHOOK)		+= rethook.o
 obj-$(CONFIG_VMCORE_INFO)	+= vmcore_info_$(BITS).o
diff --git a/arch/x86/kernel/i8253.c b/arch/x86/kernel/i8253.c
index cb9852ad6098..0b991035f127 100644
--- a/arch/x86/kernel/i8253.c
+++ b/arch/x86/kernel/i8253.c
@@ -31,7 +31,7 @@ struct clock_event_device *global_clock_event;
  */
 static bool __init use_pit(void)
 {
-	if (!IS_ENABLED(CONFIG_X86_TSC) || !boot_cpu_has(X86_FEATURE_TSC))
+	if (!boot_cpu_has(X86_FEATURE_TSC))
 		return true;
 
 	/* This also returns true when APIC is disabled */
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 7d3e13e14eab..5ad2c803d5a1 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -297,24 +297,11 @@ int check_tsc_unstable(void)
 }
 EXPORT_SYMBOL_GPL(check_tsc_unstable);
 
-#ifdef CONFIG_X86_TSC
 int __init notsc_setup(char *str)
 {
 	mark_tsc_unstable("boot parameter notsc");
 	return 1;
 }
-#else
-/*
- * disable flag for tsc. Takes effect by clearing the TSC cpu flag
- * in cpu/common.c
- */
-int __init notsc_setup(char *str)
-{
-	setup_clear_cpu_cap(X86_FEATURE_TSC);
-	return 1;
-}
-#endif
-
 __setup("notsc", notsc_setup);
 
 static int no_sched_irq_time;
-- 
2.51.0