x86/idt: Remove the tracing IDT completely

No more users of the tracing IDT. All exception tracepoints have been moved
into the regular handlers. Get rid of the mess which shouldn't have been
created in the first place.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170828064957.378851687@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/entry/entry_32.S

@@ -673,16 +673,8 @@ ENTRY(name)				\
 	jmp	ret_from_intr;		\
 ENDPROC(name)
 
-
-#ifdef CONFIG_TRACING
-# define TRACE_BUILD_INTERRUPT(name, nr)	BUILD_INTERRUPT3(trace_##name, nr, smp_trace_##name)
-#else
-# define TRACE_BUILD_INTERRUPT(name, nr)
-#endif
-
 #define BUILD_INTERRUPT(name, nr)		\
 	BUILD_INTERRUPT3(name, nr, smp_##name);	\
-	TRACE_BUILD_INTERRUPT(name, nr)
 
 /* The include is where all of the SMP etc. interrupts come from */
 #include <asm/entry_arch.h>
@@ -880,14 +872,14 @@ ENTRY(xen_failsafe_callback)
 ENDPROC(xen_failsafe_callback)
 
 BUILD_INTERRUPT3(xen_hvm_callback_vector, HYPERVISOR_CALLBACK_VECTOR,
-		xen_evtchn_do_upcall)
+		 xen_evtchn_do_upcall)
 
 #endif /* CONFIG_XEN */
 
 #if IS_ENABLED(CONFIG_HYPERV)
 
 BUILD_INTERRUPT3(hyperv_callback_vector, HYPERVISOR_CALLBACK_VECTOR,
-	hyperv_vector_handler)
+		 hyperv_vector_handler)
 
 #endif /* CONFIG_HYPERV */
 

arch/x86/entry/entry_64.S

@@ -748,18 +748,6 @@ ENTRY(\sym)
 END(\sym)
 .endm
 
-#ifdef CONFIG_TRACING
-#define trace(sym) trace_##sym
-#define smp_trace(sym) smp_trace_##sym
-
-.macro trace_apicinterrupt num sym
-apicinterrupt3 \num trace(\sym) smp_trace(\sym)
-.endm
-#else
-.macro trace_apicinterrupt num sym do_sym
-.endm
-#endif
-
 /* Make sure APIC interrupt handlers end up in the irqentry section: */
 #if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
 # define PUSH_SECTION_IRQENTRY	.pushsection .irqentry.text, "ax"
@@ -772,7 +760,6 @@ apicinterrupt3 \num trace(\sym) smp_trace(\sym)
 .macro apicinterrupt num sym do_sym
 PUSH_SECTION_IRQENTRY
 apicinterrupt3 \num \sym \do_sym
-trace_apicinterrupt \num \sym
 POP_SECTION_IRQENTRY
 .endm
 

arch/x86/include/asm/desc.h

@@ -421,35 +421,7 @@ static inline void set_nmi_gate(int gate, void *addr)
 }
 #endif
 
-#ifdef CONFIG_TRACING
-extern struct desc_ptr trace_idt_descr;
-extern gate_desc trace_idt_table[];
-static inline void write_trace_idt_entry(int entry, const gate_desc *gate)
-{
-	write_idt_entry(trace_idt_table, entry, gate);
-}
-
-static inline void _trace_set_gate(int gate, unsigned type, void *addr,
-				   unsigned dpl, unsigned ist, unsigned seg)
-{
-	gate_desc s;
-
-	pack_gate(&s, type, (unsigned long)addr, dpl, ist, seg);
-	/*
-	 * does not need to be atomic because it is only done once at
-	 * setup time
-	 */
-	write_trace_idt_entry(gate, &s);
-}
-#else
-static inline void write_trace_idt_entry(int entry, const gate_desc *gate)
-{
-}
-
-#define _trace_set_gate(gate, type, addr, dpl, ist, seg)
-#endif
-
-static inline void _set_gate(int gate, unsigned type, void *addr,
+static inline void _set_gate(int gate, unsigned type, const void *addr,
 			     unsigned dpl, unsigned ist, unsigned seg)
 {
 	gate_desc s;
@@ -460,28 +432,13 @@ static inline void _set_gate(int gate, unsigned type, void *addr,
 	 * setup time
 	 */
 	write_idt_entry(idt_table, gate, &s);
-	write_trace_idt_entry(gate, &s);
 }
 
-/*
- * This needs to use 'idt_table' rather than 'idt', and
- * thus use the _nonmapped_ version of the IDT, as the
- * Pentium F0 0F bugfix can have resulted in the mapped
- * IDT being write-protected.
- */
-#define set_intr_gate_notrace(n, addr)					\
-	do {								\
-		BUG_ON((unsigned)n > 0xFF);				\
-		_set_gate(n, GATE_INTERRUPT, (void *)addr, 0, 0,	\
-			  __KERNEL_CS);					\
-	} while (0)
-
-#define set_intr_gate(n, addr)						\
-	do {								\
-		set_intr_gate_notrace(n, addr);				\
-		_trace_set_gate(n, GATE_INTERRUPT, (void *)trace_##addr,\
-				0, 0, __KERNEL_CS);			\
-	} while (0)
+static inline void set_intr_gate(unsigned int n, const void *addr)
+{
+	BUG_ON(n > 0xFF);
+	_set_gate(n, GATE_INTERRUPT, addr, 0, 0, __KERNEL_CS);
+}
 
 extern unsigned long used_vectors[];
 
@@ -565,31 +522,6 @@ static inline void load_debug_idt(void)
 }
 #endif
 
-#ifdef CONFIG_TRACING
-extern atomic_t trace_idt_ctr;
-static inline bool is_trace_idt_enabled(void)
-{
-	if (atomic_read(&trace_idt_ctr))
-		return true;
-
-	return false;
-}
-
-static inline void load_trace_idt(void)
-{
-	load_idt((const struct desc_ptr *)&trace_idt_descr);
-}
-#else
-static inline bool is_trace_idt_enabled(void)
-{
-	return false;
-}
-
-static inline void load_trace_idt(void)
-{
-}
-#endif
-
 /*
  * The load_current_idt() must be called with interrupts disabled
  * to avoid races. That way the IDT will always be set back to the expected
@@ -601,8 +533,6 @@ static inline void load_current_idt(void)
 {
 	if (is_debug_idt_enabled())
 		load_debug_idt();
-	else if (is_trace_idt_enabled())
-		load_trace_idt();
 	else
 		load_idt((const struct desc_ptr *)&idt_descr);
 }

arch/x86/include/asm/hw_irq.h

@@ -46,26 +46,6 @@ extern asmlinkage void deferred_error_interrupt(void);
 extern asmlinkage void call_function_interrupt(void);
 extern asmlinkage void call_function_single_interrupt(void);
 
-#ifdef CONFIG_TRACING
-/* Interrupt handlers registered during init_IRQ */
-#define trace_reschedule_interrupt	reschedule_interrupt
-#define trace_call_function_interrupt	call_function_interrupt
-#define trace_call_function_single_interrupt	call_function_single_interrupt
-#define trace_thermal_interrupt	thermal_interrupt
-#define trace_threshold_interrupt	threshold_interrupt
-#define trace_deferred_error_interrupt	deferred_error_interrupt
-#define trace_irq_work_interrupt irq_work_interrupt
-#define trace_error_interrupt error_interrupt
-#define trace_spurious_interrupt spurious_interrupt
-#define trace_x86_platform_ipi	x86_platform_ipi
-#define trace_apic_timer_interrupt	apic_timer_interrupt
-#define trace_irq_move_cleanup_interrupt  irq_move_cleanup_interrupt
-#define trace_reboot_interrupt  reboot_interrupt
-#define trace_kvm_posted_intr_ipi kvm_posted_intr_ipi
-#define trace_kvm_posted_intr_wakeup_ipi kvm_posted_intr_wakeup_ipi
-#define trace_kvm_posted_intr_nested_ipi kvm_posted_intr_nested_ipi
-#endif /* CONFIG_TRACING */
-
 #ifdef	CONFIG_X86_LOCAL_APIC
 struct irq_data;
 struct pci_dev;

arch/x86/include/asm/segment.h

@@ -238,9 +238,6 @@
 #ifndef __ASSEMBLY__
 
 extern const char early_idt_handler_array[NUM_EXCEPTION_VECTORS][EARLY_IDT_HANDLER_SIZE];
-#ifdef CONFIG_TRACING
-# define trace_early_idt_handler_array early_idt_handler_array
-#endif
 
 /*
  * Load a segment. Fall back on loading the zero segment if something goes

arch/x86/kernel/tracepoint.c

@@ -10,58 +10,15 @@
 #include <asm/hw_irq.h>
 #include <asm/desc.h>
 
-atomic_t trace_idt_ctr = ATOMIC_INIT(0);
-struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1,
-				(unsigned long) trace_idt_table };
-
-/* No need to be aligned, but done to keep all IDTs defined the same way. */
-gate_desc trace_idt_table[NR_VECTORS] __page_aligned_bss;
-
 DEFINE_STATIC_KEY_FALSE(trace_irqvectors_key);
-static int trace_irq_vector_refcount;
-static DEFINE_MUTEX(irq_vector_mutex);
-
-static void set_trace_idt_ctr(int val)
-{
-	atomic_set(&trace_idt_ctr, val);
-	/* Ensure the trace_idt_ctr is set before sending IPI */
-	wmb();
-}
-
-static void switch_idt(void *arg)
-{
-	unsigned long flags;
-
-	local_irq_save(flags);
-	load_current_idt();
-	local_irq_restore(flags);
-}
 
 int trace_irq_vector_regfunc(void)
 {
 	static_branch_inc(&trace_irqvectors_key);
-
-	mutex_lock(&irq_vector_mutex);
-	if (!trace_irq_vector_refcount) {
-		set_trace_idt_ctr(1);
-		smp_call_function(switch_idt, NULL, 0);
-		switch_idt(NULL);
-	}
-	trace_irq_vector_refcount++;
-	mutex_unlock(&irq_vector_mutex);
 	return 0;
 }
 
 void trace_irq_vector_unregfunc(void)
 {
 	static_branch_dec(&trace_irqvectors_key);
-
-	mutex_lock(&irq_vector_mutex);
-	trace_irq_vector_refcount--;
-	if (!trace_irq_vector_refcount) {
-		set_trace_idt_ctr(0);
-		smp_call_function(switch_idt, NULL, 0);
-		switch_idt(NULL);
-	}
-	mutex_unlock(&irq_vector_mutex);
 }

arch/x86/kernel/traps.c

@@ -939,12 +939,8 @@ void __init early_trap_init(void)
 	 * stack.  Using the original stack works well enough at this
 	 * early stage. DEBUG_STACK will be equipped after cpu_init() in
 	 * trap_init().
-	 *
-	 * We don't need to set trace_idt_table like set_intr_gate(),
-	 * since we don't have trace_debug and it will be reset to
-	 * 'debug' in trap_init() by set_intr_gate_ist().
 	 */
-	set_intr_gate_notrace(X86_TRAP_DB, debug);
+	set_intr_gate(X86_TRAP_DB, debug);
 	/* int3 can be called from all */
 	set_system_intr_gate(X86_TRAP_BP, &int3);
 #ifdef CONFIG_X86_32