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x86/idt: Remove the tracing IDT completely
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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>
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Thomas Gleixner authored and Ingo Molnar committed Aug 29, 2017
1 parent 3cd788c commit 4b9a8dc
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Showing 7 changed files with 9 additions and 170 deletions.
12 changes: 2 additions & 10 deletions arch/x86/entry/entry_32.S
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Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -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 */

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13 changes: 0 additions & 13 deletions arch/x86/entry/entry_64.S
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Original file line number Diff line number Diff line change
Expand Up @@ -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"
Expand All @@ -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

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82 changes: 6 additions & 76 deletions arch/x86/include/asm/desc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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[];

Expand Down Expand Up @@ -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
Expand All @@ -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);
}
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20 changes: 0 additions & 20 deletions arch/x86/include/asm/hw_irq.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down
3 changes: 0 additions & 3 deletions arch/x86/include/asm/segment.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down
43 changes: 0 additions & 43 deletions arch/x86/kernel/tracepoint.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
}
6 changes: 1 addition & 5 deletions arch/x86/kernel/traps.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down

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