[PATCH v2 02/14] context_tracking: Add ct_state and CT_WARN_ON

From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: "Frédéric Weisbecker" <fweisbec@gmail.com>,
	"Rik van Riel" <riel@redhat.com>,
	"Oleg Nesterov" <oleg@redhat.com>,
	"Denys Vlasenko" <vda.linux@googlemail.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"Kees Cook" <keescook@chromium.org>,
	"Brian Gerst" <brgerst@gmail.com>,
	paulmck@linux.vnet.ibm.com, "Andy Lutomirski" <luto@kernel.org>
Subject: [PATCH v2 02/14] context_tracking: Add ct_state and CT_WARN_ON
Date: Thu, 18 Jun 2015 12:08:34 -0700	[thread overview]
Message-ID: <30a8c36bb4a5cba8947780ebe99e8ea3d3fb995f.1434654252.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1434654252.git.luto@kernel.org>
In-Reply-To: <cover.1434654252.git.luto@kernel.org>

This will let us sprinkle sanity checks around the kernel without
making too much of a mess.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 include/linux/context_tracking.h       | 15 +++++++++++++++
 include/linux/context_tracking_state.h |  1 +
 2 files changed, 16 insertions(+)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 2821838256b4..3f5ac9b86f69 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -57,6 +57,19 @@ static inline void context_tracking_task_switch(struct task_struct *prev,
 	if (context_tracking_is_enabled())
 		__context_tracking_task_switch(prev, next);
 }
+
+/**
+ * ct_state() - return the current context tracking state if known
+ *
+ * Returns the current cpu's context tracking state if context tracking
+ * is enabled.  If context tracking is disabled, returns
+ * CONTEXT_DISABLED.  This should be used primarily for debugging.
+ */
+static inline enum ctx_state ct_state(void)
+{
+	return context_tracking_is_enabled() ?
+		this_cpu_read(context_tracking.state) : CONTEXT_DISABLED;
+}
 #else
 static inline void user_enter(void) { }
 static inline void user_exit(void) { }
@@ -64,8 +77,10 @@ static inline enum ctx_state exception_enter(void) { return 0; }
 static inline void exception_exit(enum ctx_state prev_ctx) { }
 static inline void context_tracking_task_switch(struct task_struct *prev,
 						struct task_struct *next) { }
+static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
 #endif /* !CONFIG_CONTEXT_TRACKING */
 
+#define CT_WARN_ON(cond) WARN_ON(context_tracking_is_enabled() && (cond))
 
 #ifdef CONFIG_CONTEXT_TRACKING_FORCE
 extern void context_tracking_init(void);
diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index 6b7b96a32b75..d4aec2805849 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -13,6 +13,7 @@ struct context_tracking {
 	 */
 	bool active;
 	enum ctx_state {
+		CONTEXT_DISABLED = -1,	/* returned by ct_state() if unknown */
 		CONTEXT_KERNEL = 0,
 		CONTEXT_USER,
 		CONTEXT_GUEST,
-- 
2.4.3

