From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 28 Aug 2017 08:47:21 +0200 Subject: [PATCH] x86/tracing: Introduce a static key for exception tracing MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit CVE-2017-5754 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 Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20170828064956.593094539@linutronix.de Signed-off-by: Ingo Molnar (cherry picked from commit 2feb1b316d48004d905278c02a55902cab0be8be) Signed-off-by: Andy Whitcroft (cherry picked from commit 15e0ff2a63fdd93f8881e2ebba5c048c5b601e57) Signed-off-by: Andy Whitcroft Signed-off-by: Kleber Sacilotto de Souza (cherry picked from commit d58a56e851c339d8d9d311dc9b4fad6abbf8bf19) Signed-off-by: Fabian Grünbichler --- arch/x86/include/asm/trace/common.h | 15 +++++++++++++++ arch/x86/include/asm/trace/exceptions.h | 4 +--- arch/x86/include/asm/trace/irq_vectors.h | 4 +--- arch/x86/kernel/tracepoint.c | 9 ++++++++- 4 files changed, 25 insertions(+), 7 deletions(-) create mode 100644 arch/x86/include/asm/trace/common.h diff --git a/arch/x86/include/asm/trace/common.h b/arch/x86/include/asm/trace/common.h new file mode 100644 index 000000000000..b1eb7b18ee8a --- /dev/null +++ b/arch/x86/include/asm/trace/common.h @@ -0,0 +1,15 @@ +#ifndef _ASM_TRACE_COMMON_H +#define _ASM_TRACE_COMMON_H + +extern int trace_irq_vector_regfunc(void); +extern void trace_irq_vector_unregfunc(void); + +#ifdef CONFIG_TRACING +DECLARE_STATIC_KEY_FALSE(trace_irqvectors_key); +#define trace_irqvectors_enabled() \ + static_branch_unlikely(&trace_irqvectors_key) +#else +static inline bool trace_irqvectors_enabled(void) { return false; } +#endif + +#endif diff --git a/arch/x86/include/asm/trace/exceptions.h b/arch/x86/include/asm/trace/exceptions.h index 2422b14c50a7..960a5b50ac3b 100644 --- a/arch/x86/include/asm/trace/exceptions.h +++ b/arch/x86/include/asm/trace/exceptions.h @@ -5,9 +5,7 @@ #define _TRACE_PAGE_FAULT_H #include - -extern int trace_irq_vector_regfunc(void); -extern void trace_irq_vector_unregfunc(void); +#include DECLARE_EVENT_CLASS(x86_exceptions, diff --git a/arch/x86/include/asm/trace/irq_vectors.h b/arch/x86/include/asm/trace/irq_vectors.h index 32dd6a9e343c..7825b4426e7e 100644 --- a/arch/x86/include/asm/trace/irq_vectors.h +++ b/arch/x86/include/asm/trace/irq_vectors.h @@ -5,9 +5,7 @@ #define _TRACE_IRQ_VECTORS_H #include - -extern int trace_irq_vector_regfunc(void); -extern void trace_irq_vector_unregfunc(void); +#include DECLARE_EVENT_CLASS(x86_irq_vector, diff --git a/arch/x86/kernel/tracepoint.c b/arch/x86/kernel/tracepoint.c index 15515132bf0d..dd4aa04bb95c 100644 --- a/arch/x86/kernel/tracepoint.c +++ b/arch/x86/kernel/tracepoint.c @@ -4,9 +4,11 @@ * Copyright (C) 2013 Seiji Aguchi * */ +#include +#include + #include #include -#include atomic_t trace_idt_ctr = ATOMIC_INIT(0); struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1, @@ -15,6 +17,7 @@ struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1, /* 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); @@ -36,6 +39,8 @@ static void switch_idt(void *arg) 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); @@ -49,6 +54,8 @@ int trace_irq_vector_regfunc(void) 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) { -- 2.14.2