From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
Brian Gerst <brgerst@gmail.com>, Juergen Gross <jgross@suse.com>,
Frederic Weisbecker <frederic@kernel.org>,
Alexandre Chartre <alexandre.chartre@oracle.com>
Subject: [patch part-II V2 01/13] context_tracking: Ensure that the critical path cannot be instrumented
Date: Sun, 08 Mar 2020 23:24:00 +0100 [thread overview]
Message-ID: <20200308222609.017810037@linutronix.de> (raw)
In-Reply-To: 20200308222359.370649591@linutronix.de
context tracking lacks a few protection mechanisms against instrumentation:
- While the core functions are marked NOKPROBE they lack protection
against function tracing which is required as the function entry/exit
points can be utilized by BPF.
- static functions invoked from the protected functions need to be marked
as well as they can be instrumented otherwise.
- using plain inline allows the compiler to emit traceable and probable
functions.
Fix this by adding the missing notrace/NOKPROBE annotations and converting
the plain inlines to __always_inline.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/context_tracking.h | 14 +++++++-------
include/linux/context_tracking_state.h | 6 +++---
kernel/context_tracking.c | 9 +++++----
3 files changed, 15 insertions(+), 14 deletions(-)
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -20,32 +20,32 @@ extern void context_tracking_exit(enum c
extern void context_tracking_user_enter(void);
extern void context_tracking_user_exit(void);
-static inline void user_enter(void)
+static __always_inline void user_enter(void)
{
if (context_tracking_enabled())
context_tracking_enter(CONTEXT_USER);
}
-static inline void user_exit(void)
+static __always_inline void user_exit(void)
{
if (context_tracking_enabled())
context_tracking_exit(CONTEXT_USER);
}
/* Called with interrupts disabled. */
-static inline void user_enter_irqoff(void)
+static __always_inline void user_enter_irqoff(void)
{
if (context_tracking_enabled())
__context_tracking_enter(CONTEXT_USER);
}
-static inline void user_exit_irqoff(void)
+static __always_inline void user_exit_irqoff(void)
{
if (context_tracking_enabled())
__context_tracking_exit(CONTEXT_USER);
}
-static inline enum ctx_state exception_enter(void)
+static __always_inline enum ctx_state exception_enter(void)
{
enum ctx_state prev_ctx;
@@ -59,7 +59,7 @@ static inline enum ctx_state exception_e
return prev_ctx;
}
-static inline void exception_exit(enum ctx_state prev_ctx)
+static __always_inline void exception_exit(enum ctx_state prev_ctx)
{
if (context_tracking_enabled()) {
if (prev_ctx != CONTEXT_KERNEL)
@@ -75,7 +75,7 @@ static inline void exception_exit(enum c
* 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)
+static __always_inline enum ctx_state ct_state(void)
{
return context_tracking_enabled() ?
this_cpu_read(context_tracking.state) : CONTEXT_DISABLED;
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -26,12 +26,12 @@ struct context_tracking {
extern struct static_key_false context_tracking_key;
DECLARE_PER_CPU(struct context_tracking, context_tracking);
-static inline bool context_tracking_enabled(void)
+static __always_inline bool context_tracking_enabled(void)
{
return static_branch_unlikely(&context_tracking_key);
}
-static inline bool context_tracking_enabled_cpu(int cpu)
+static __always_inline bool context_tracking_enabled_cpu(int cpu)
{
return context_tracking_enabled() && per_cpu(context_tracking.active, cpu);
}
@@ -41,7 +41,7 @@ static inline bool context_tracking_enab
return context_tracking_enabled() && __this_cpu_read(context_tracking.active);
}
-static inline bool context_tracking_in_user(void)
+static __always_inline bool context_tracking_in_user(void)
{
return __this_cpu_read(context_tracking.state) == CONTEXT_USER;
}
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -31,7 +31,7 @@ EXPORT_SYMBOL_GPL(context_tracking_key);
DEFINE_PER_CPU(struct context_tracking, context_tracking);
EXPORT_SYMBOL_GPL(context_tracking);
-static bool context_tracking_recursion_enter(void)
+static notrace bool context_tracking_recursion_enter(void)
{
int recursion;
@@ -44,8 +44,9 @@ static bool context_tracking_recursion_e
return false;
}
+NOKPROBE_SYMBOL(context_tracking_recursion_enter);
-static void context_tracking_recursion_exit(void)
+static __always_inline void context_tracking_recursion_exit(void)
{
__this_cpu_dec(context_tracking.recursion);
}
@@ -59,7 +60,7 @@ static void context_tracking_recursion_e
* instructions to execute won't use any RCU read side critical section
* because this function sets RCU in extended quiescent state.
*/
-void __context_tracking_enter(enum ctx_state state)
+void notrace __context_tracking_enter(enum ctx_state state)
{
/* Kernel threads aren't supposed to go to userspace */
WARN_ON_ONCE(!current->mm);
@@ -142,7 +143,7 @@ NOKPROBE_SYMBOL(context_tracking_user_en
* This call supports re-entrancy. This way it can be called from any exception
* handler without needing to know if we came from userspace or not.
*/
-void __context_tracking_exit(enum ctx_state state)
+void notrace __context_tracking_exit(enum ctx_state state)
{
if (!context_tracking_recursion_enter())
return;
next prev parent reply other threads:[~2020-03-08 23:24 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-08 22:23 [patch part-II V2 00/13] x86/entry: Consolidation - Part II (syscalls) Thomas Gleixner
2020-03-08 22:24 ` Thomas Gleixner [this message]
2020-03-09 14:22 ` [patch part-II V2 01/13] context_tracking: Ensure that the critical path cannot be instrumented Frederic Weisbecker
2020-03-09 14:40 ` Thomas Gleixner
2020-03-10 10:12 ` Alexandre Chartre
2020-03-08 22:24 ` [patch part-II V2 02/13] x86/entry: Mark enter_from_user_mode() notrace and NOKPROBE Thomas Gleixner
2020-03-09 15:14 ` Frederic Weisbecker
2020-03-09 15:40 ` Thomas Gleixner
2020-03-11 22:21 ` Frederic Weisbecker
2020-03-10 10:15 ` Alexandre Chartre
2020-03-08 22:24 ` [patch part-II V2 03/13] x86/entry/32: Remove unused label restore_nocheck Thomas Gleixner
2020-03-10 10:16 ` Alexandre Chartre
2020-03-10 13:02 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-03-08 22:24 ` [patch part-II V2 04/13] x86/entry/64: Trace irqflags unconditionally as ON when returning to user space Thomas Gleixner
2020-03-10 10:25 ` Alexandre Chartre
2020-03-10 13:02 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-03-08 22:24 ` [patch part-II V2 05/13] x86/entry/common: Consolidate syscall entry code Thomas Gleixner
2020-03-08 22:24 ` [patch part-II V2 06/13] x86/entry/common: Mark syscall entry points notrace and NOKPROBE Thomas Gleixner
2020-03-13 15:12 ` Frederic Weisbecker
2020-03-08 22:24 ` [patch part-II V2 07/13] x86/entry: Move irq tracing on syscall entry to C-code Thomas Gleixner
2020-03-13 15:16 ` Frederic Weisbecker
2020-03-13 23:17 ` Thomas Gleixner
2020-03-08 22:24 ` [patch part-II V2 08/13] tracing: Provide lockdep less trace_hardirqs_on/off() variants Thomas Gleixner
2020-03-10 10:55 ` Alexandre Chartre
2020-03-10 11:08 ` Borislav Petkov
2020-03-10 11:21 ` Alexandre Chartre
2020-03-08 22:24 ` [patch part-II V2 09/13] x86/entry/common: Split hardirq tracing into lockdep and ftrace parts Thomas Gleixner
2020-03-10 11:20 ` Borislav Petkov
2020-03-10 13:40 ` Steven Rostedt
2020-03-10 13:28 ` Alexandre Chartre
2020-03-23 9:08 ` [x86/entry/common] bae397f6e7: WARNING:at_kernel/sched/cputime.c:#get_vtime_delta kernel test robot
2020-03-08 22:24 ` [patch part-II V2 10/13] x86/entry/common: Split prepare_exit_to_usermode() and syscall_return_slowpath() Thomas Gleixner
2020-03-10 13:37 ` Alexandre Chartre
2020-03-08 22:24 ` [patch part-II V2 11/13] x86/speculation/mds: Mark mds_user_clear_cpu_buffers() __always_inline Thomas Gleixner
2020-03-10 13:48 ` Alexandre Chartre
2020-03-10 16:38 ` Thomas Gleixner
2020-03-08 22:24 ` [patch part-II V2 12/13] x86/entry: Move irq flags tracing to prepare_exit_to_usermode() Thomas Gleixner
2020-03-10 14:03 ` Alexandre Chartre
2020-03-08 22:24 ` [patch part-II V2 13/13] x86/entry/common: Split irq tracing in prepare_exit_to_usermode() Thomas Gleixner
2020-03-10 14:09 ` Alexandre Chartre
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