2feb1b316d
Switching the IDT just for avoiding tracepoints creates a completely impenetrable macro/inline/ifdef mess. There is no point in avoiding tracepoints for most of the traps/exceptions. For the more expensive tracepoints, like pagefaults, this can be handled with an explicit static key. Preparatory patch to remove the tracing IDT. 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/20170828064956.593094539@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
68 lines
1.5 KiB
C
68 lines
1.5 KiB
C
/*
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* Code for supporting irq vector tracepoints.
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*
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* Copyright (C) 2013 Seiji Aguchi <seiji.aguchi@hds.com>
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*
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*/
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#include <linux/jump_label.h>
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#include <linux/atomic.h>
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#include <asm/hw_irq.h>
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#include <asm/desc.h>
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atomic_t trace_idt_ctr = ATOMIC_INIT(0);
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struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1,
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(unsigned long) trace_idt_table };
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/* No need to be aligned, but done to keep all IDTs defined the same way. */
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gate_desc trace_idt_table[NR_VECTORS] __page_aligned_bss;
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DEFINE_STATIC_KEY_FALSE(trace_irqvectors_key);
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static int trace_irq_vector_refcount;
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static DEFINE_MUTEX(irq_vector_mutex);
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static void set_trace_idt_ctr(int val)
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{
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atomic_set(&trace_idt_ctr, val);
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/* Ensure the trace_idt_ctr is set before sending IPI */
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wmb();
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}
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static void switch_idt(void *arg)
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{
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unsigned long flags;
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local_irq_save(flags);
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load_current_idt();
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local_irq_restore(flags);
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}
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int trace_irq_vector_regfunc(void)
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{
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static_branch_inc(&trace_irqvectors_key);
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mutex_lock(&irq_vector_mutex);
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if (!trace_irq_vector_refcount) {
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set_trace_idt_ctr(1);
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smp_call_function(switch_idt, NULL, 0);
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switch_idt(NULL);
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}
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trace_irq_vector_refcount++;
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mutex_unlock(&irq_vector_mutex);
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return 0;
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}
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void trace_irq_vector_unregfunc(void)
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{
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static_branch_dec(&trace_irqvectors_key);
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mutex_lock(&irq_vector_mutex);
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trace_irq_vector_refcount--;
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if (!trace_irq_vector_refcount) {
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set_trace_idt_ctr(0);
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smp_call_function(switch_idt, NULL, 0);
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switch_idt(NULL);
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}
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mutex_unlock(&irq_vector_mutex);
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}
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