From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Paul McKenney <paulmck@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
"Joel Fernandes (Google)" <joel@joelfernandes.org>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Brian Gerst <brgerst@gmail.com>, Juergen Gross <jgross@suse.com>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Peter Zijlstra <peterz@infradead.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org
Subject: [patch V3 08/23] x86/entry: Mark enter_from_user_mode() noinstr
Date: Fri, 20 Mar 2020 19:00:04 +0100 [thread overview]
Message-ID: <20200320180033.187967761@linutronix.de> (raw)
In-Reply-To: 20200320175956.033706968@linutronix.de
Both the callers in the low level ASM code and __context_tracking_exit()
which is invoked from enter_from_user_mode() via user_exit_irqoff() are
marked NOKPROBE. Allowing enter_from_user_mode() to be probed is
inconsistent at best.
Aside of that while function tracing per se is safe the function trace
entry/exit points can be used via BPF as well which is not safe to use
before context tracking has reached CONTEXT_KERNEL and adjusted RCU.
Mark it noinstr which moves it into the instrumentation protected text
section and includes notrace.
Note, this needs further fixups in context tracking to ensure that the
full call chain is protected. Will be addressed in follow up changes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/entry/common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -40,7 +40,7 @@
#ifdef CONFIG_CONTEXT_TRACKING
/* Called on entry from user mode with IRQs off. */
-__visible inline void enter_from_user_mode(void)
+__visible noinstr void enter_from_user_mode(void)
{
CT_WARN_ON(ct_state() != CONTEXT_USER);
user_exit_irqoff();
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Paul McKenney <paulmck@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
"Joel Fernandes (Google)" <joel@joelfernandes.org>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Brian Gerst <brgerst@gmail.com>, Juergen Gross <jgross@suse.com>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Peter Zijlstra <peterz@infradead.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org
Subject: [RESEND][patch V3 08/23] x86/entry: Mark enter_from_user_mode() noinstr
Date: Fri, 20 Mar 2020 19:00:04 +0100 [thread overview]
Message-ID: <20200320180033.187967761@linutronix.de> (raw)
Message-ID: <20200320180004.7P81KwoWeBdUD8l-oF-q0K1hpbhtIGR3szcJBYIzvnQ@z> (raw)
In-Reply-To: 20200320175956.033706968@linutronix.de
Both the callers in the low level ASM code and __context_tracking_exit()
which is invoked from enter_from_user_mode() via user_exit_irqoff() are
marked NOKPROBE. Allowing enter_from_user_mode() to be probed is
inconsistent at best.
Aside of that while function tracing per se is safe the function trace
entry/exit points can be used via BPF as well which is not safe to use
before context tracking has reached CONTEXT_KERNEL and adjusted RCU.
Mark it noinstr which moves it into the instrumentation protected text
section and includes notrace.
Note, this needs further fixups in context tracking to ensure that the
full call chain is protected. Will be addressed in follow up changes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/entry/common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -40,7 +40,7 @@
#ifdef CONFIG_CONTEXT_TRACKING
/* Called on entry from user mode with IRQs off. */
-__visible inline void enter_from_user_mode(void)
+__visible noinstr void enter_from_user_mode(void)
{
CT_WARN_ON(ct_state() != CONTEXT_USER);
user_exit_irqoff();
next prev parent reply other threads:[~2020-03-20 18:39 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-20 17:59 [patch V3 00/23] x86/entry: Consolidation part II (syscalls) Thomas Gleixner
2020-03-20 17:59 ` [RESEND][patch " Thomas Gleixner
2020-03-20 17:59 ` [patch V3 01/23] rcu: Dont acquire lock in NMI handler in rcu_nmi_enter_common() Thomas Gleixner
2020-03-20 17:59 ` [RESEND][patch " Thomas Gleixner
2020-03-24 15:37 ` [patch " Frederic Weisbecker
2020-03-20 17:59 ` [patch V3 02/23] rcu: Add comments marking transitions between RCU watching and not Thomas Gleixner
2020-03-20 17:59 ` [RESEND][patch " Thomas Gleixner
2020-03-24 15:38 ` [patch " Frederic Weisbecker
2020-03-20 17:59 ` [patch V3 03/23] vmlinux.lds.h: Create section for protection against instrumentation Thomas Gleixner
2020-03-20 17:59 ` [RESEND][patch " Thomas Gleixner
2020-03-24 12:26 ` Borislav Petkov
2020-04-03 8:08 ` Alexandre Chartre
2020-03-20 18:00 ` [patch V3 04/23] kprobes: Prevent probes in .noinstr.text section Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-23 14:00 ` [patch " Masami Hiramatsu
2020-03-23 16:03 ` Thomas Gleixner
2020-03-24 5:49 ` Masami Hiramatsu
2020-03-24 9:47 ` Thomas Gleixner
2020-03-25 13:39 ` Masami Hiramatsu
2020-03-20 18:00 ` [patch V3 05/23] tracing: Provide lockdep less trace_hardirqs_on/off() variants Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-04-03 8:34 ` Alexandre Chartre
2020-03-20 18:00 ` [patch V3 06/23] bug: Annotate WARN/BUG/stackfail as noinstr safe Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-04-02 21:01 ` Josh Poimboeuf
2020-04-02 21:34 ` Peter Zijlstra
2020-04-02 21:43 ` Josh Poimboeuf
2020-04-02 21:49 ` Thomas Gleixner
2020-03-20 18:00 ` [patch V3 07/23] lockdep: Prepare for noinstr sections Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` Thomas Gleixner [this message]
2020-03-20 18:00 ` [RESEND][patch V3 08/23] x86/entry: Mark enter_from_user_mode() noinstr Thomas Gleixner
2020-03-20 18:00 ` [patch V3 09/23] x86/entry/common: Protect against instrumentation Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 10/23] x86/entry: Move irq tracing on syscall entry to C-code Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 11/23] x86/entry: Move irq flags tracing to prepare_exit_to_usermode() Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 12/23] context_tracking: Ensure that the critical path cannot be instrumented Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 13/23] lib/smp_processor_id: Move it into noinstr section Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 14/23] x86/speculation/mds: Mark mds_user_clear_cpu_buffers() __always_inline Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 15/23] x86/entry/64: Check IF in __preempt_enable_notrace() thunk Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 16/23] x86/entry/64: Mark ___preempt_schedule_notrace() thunk noinstr Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 17/23] rcu/tree: Mark the idle relevant functions noinstr Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-24 16:09 ` Paul E. McKenney
2020-03-24 19:28 ` Thomas Gleixner
2020-03-24 19:58 ` Paul E. McKenney
2020-03-20 18:00 ` [patch V3 18/23] x86/kvm: Move context tracking where it belongs Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 19/23] x86/kvm/vmx: Add hardirq tracing to guest enter/exit Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-24 23:03 ` Peter Zijlstra
2020-03-24 23:21 ` Thomas Gleixner
2020-03-20 18:00 ` [patch V3 20/23] x86/kvm/svm: Handle hardirqs proper on " Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 21/23] context_tracking: Make guest_enter/exit_irqoff() .noinstr ready Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 22/23] x86/kvm/vmx: Move guest enter/exit into .noinstr.text Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 23/23] x86/kvm/svm: " Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch " Thomas Gleixner
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