139 lines
4.6 KiB
Diff
139 lines
4.6 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Mon, 28 Aug 2017 08:47:21 +0200
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Subject: [PATCH] x86/tracing: Introduce a static key for exception tracing
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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CVE-2017-5754
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Switching the IDT just for avoiding tracepoints creates a completely
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impenetrable macro/inline/ifdef mess.
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There is no point in avoiding tracepoints for most of the traps/exceptions.
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For the more expensive tracepoints, like pagefaults, this can be handled with
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an explicit static key.
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Preparatory patch to remove the tracing IDT.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Cc: Andy Lutomirski <luto@kernel.org>
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Cc: Borislav Petkov <bp@alien8.de>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Steven Rostedt <rostedt@goodmis.org>
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Link: http://lkml.kernel.org/r/20170828064956.593094539@linutronix.de
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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(cherry picked from commit 2feb1b316d48004d905278c02a55902cab0be8be)
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Signed-off-by: Andy Whitcroft <apw@kathleen.maas>
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(cherry picked from commit 15e0ff2a63fdd93f8881e2ebba5c048c5b601e57)
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Signed-off-by: Andy Whitcroft <apw@canonical.com>
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Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
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(cherry picked from commit d58a56e851c339d8d9d311dc9b4fad6abbf8bf19)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/include/asm/trace/common.h | 15 +++++++++++++++
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arch/x86/include/asm/trace/exceptions.h | 4 +---
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arch/x86/include/asm/trace/irq_vectors.h | 4 +---
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arch/x86/kernel/tracepoint.c | 9 ++++++++-
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4 files changed, 25 insertions(+), 7 deletions(-)
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create mode 100644 arch/x86/include/asm/trace/common.h
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diff --git a/arch/x86/include/asm/trace/common.h b/arch/x86/include/asm/trace/common.h
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new file mode 100644
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index 000000000000..b1eb7b18ee8a
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--- /dev/null
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+++ b/arch/x86/include/asm/trace/common.h
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@@ -0,0 +1,15 @@
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+#ifndef _ASM_TRACE_COMMON_H
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+#define _ASM_TRACE_COMMON_H
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+
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+extern int trace_irq_vector_regfunc(void);
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+extern void trace_irq_vector_unregfunc(void);
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+
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+#ifdef CONFIG_TRACING
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+DECLARE_STATIC_KEY_FALSE(trace_irqvectors_key);
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+#define trace_irqvectors_enabled() \
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+ static_branch_unlikely(&trace_irqvectors_key)
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+#else
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+static inline bool trace_irqvectors_enabled(void) { return false; }
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+#endif
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+
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+#endif
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diff --git a/arch/x86/include/asm/trace/exceptions.h b/arch/x86/include/asm/trace/exceptions.h
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index 2422b14c50a7..960a5b50ac3b 100644
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--- a/arch/x86/include/asm/trace/exceptions.h
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+++ b/arch/x86/include/asm/trace/exceptions.h
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@@ -5,9 +5,7 @@
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#define _TRACE_PAGE_FAULT_H
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#include <linux/tracepoint.h>
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-
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-extern int trace_irq_vector_regfunc(void);
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-extern void trace_irq_vector_unregfunc(void);
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+#include <asm/trace/common.h>
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DECLARE_EVENT_CLASS(x86_exceptions,
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diff --git a/arch/x86/include/asm/trace/irq_vectors.h b/arch/x86/include/asm/trace/irq_vectors.h
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index 32dd6a9e343c..7825b4426e7e 100644
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--- a/arch/x86/include/asm/trace/irq_vectors.h
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+++ b/arch/x86/include/asm/trace/irq_vectors.h
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@@ -5,9 +5,7 @@
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#define _TRACE_IRQ_VECTORS_H
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#include <linux/tracepoint.h>
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-
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-extern int trace_irq_vector_regfunc(void);
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-extern void trace_irq_vector_unregfunc(void);
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+#include <asm/trace/common.h>
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DECLARE_EVENT_CLASS(x86_irq_vector,
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diff --git a/arch/x86/kernel/tracepoint.c b/arch/x86/kernel/tracepoint.c
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index 15515132bf0d..dd4aa04bb95c 100644
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--- a/arch/x86/kernel/tracepoint.c
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+++ b/arch/x86/kernel/tracepoint.c
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@@ -4,9 +4,11 @@
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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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+
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#include <asm/hw_irq.h>
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#include <asm/desc.h>
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-#include <linux/atomic.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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@@ -15,6 +17,7 @@ struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1,
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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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@@ -36,6 +39,8 @@ static void switch_idt(void *arg)
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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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+
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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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@@ -49,6 +54,8 @@ int trace_irq_vector_regfunc(void)
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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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+
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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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--
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2.14.2
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