From: Peter Zijlstra <peterz@infradead.org>
To: tglx@linutronix.de, luto@amacapital.net, peterz@infradead.org
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
Lai Jiangshan <laijs@linux.alibaba.com>,
sean.j.christopherson@intel.com, andrew.cooper3@citrix.com,
daniel.thompson@linaro.org, a.darwish@linutronix.de,
rostedt@goodmis.org, bigeasy@linutronix.de
Subject: [PATCH 13/14] lockdep: Prepare for NMI IRQ state tracking
Date: Fri, 29 May 2020 23:27:41 +0200 [thread overview]
Message-ID: <20200529213321.471984676@infradead.org> (raw)
In-Reply-To: 20200529212728.795169701@infradead.org
There is no reason not to always, accurately, track IRQ state.
This change also makes IRQ state tracking ignore lockdep_off().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/locking/lockdep.c | 33 ++++++++++++++++++++++++++++++---
1 file changed, 30 insertions(+), 3 deletions(-)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3646,7 +3646,13 @@ static void __trace_hardirqs_on_caller(v
*/
void lockdep_hardirqs_on_prepare(unsigned long ip)
{
- if (unlikely(!debug_locks || current->lockdep_recursion))
+ /*
+ * NMIs do not (and cannot) track lock dependencies, nothing to do.
+ */
+ if (in_nmi())
+ return;
+
+ if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
return;
if (unlikely(current->hardirqs_enabled)) {
@@ -3692,7 +3698,24 @@ void noinstr lockdep_hardirqs_on(unsigne
{
struct task_struct *curr = current;
- if (unlikely(!debug_locks || curr->lockdep_recursion))
+ /*
+ * NMIs can happen in the middle of local_irq_{en,dis}able() where the
+ * tracking state and hardware state are out of sync.
+ *
+ * NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from,
+ * and not rely on hardware state like normal interrupts.
+ */
+ if (in_nmi()) {
+ /*
+ * Skip:
+ * - recursion check, because NMI can hit lockdep;
+ * - hardware state check, because above;
+ * - chain_key check, see lockdep_hardirqs_on_prepare().
+ */
+ goto skip_checks;
+ }
+
+ if (DEBUG_LOCKS_WARN_ON(curr->lockdep_recursion & LOCKDEP_RECURSION_MASK))
return;
if (curr->hardirqs_enabled) {
@@ -3720,6 +3743,7 @@ void noinstr lockdep_hardirqs_on(unsigne
DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key !=
current->curr_chain_key);
+skip_checks:
/* we'll do an OFF -> ON transition: */
curr->hardirqs_enabled = 1;
curr->hardirq_enable_ip = ip;
@@ -3735,7 +3759,10 @@ void noinstr lockdep_hardirqs_off(unsign
{
struct task_struct *curr = current;
- if (unlikely(!debug_locks || curr->lockdep_recursion))
+ /*
+ * NMIs can happen in lockdep.
+ */
+ if (!in_nmi() && DEBUG_LOCKS_WARN_ON(curr->lockdep_recursion & LOCKDEP_RECURSION_MASK))
return;
/*
next prev parent reply other threads:[~2020-05-29 21:35 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-29 21:27 [PATCH 00/14] x86/entry: disallow #DB more and x86/entry lockdep/nmi Peter Zijlstra
2020-05-29 21:27 ` [PATCH 01/14] x86/hw_breakpoint: Add within_area() to check data breakpoints Peter Zijlstra
2020-05-29 21:27 ` [PATCH 02/14] x86/hw_breakpoint: Prevent data breakpoints on direct GDT Peter Zijlstra
2020-05-30 12:45 ` Andrew Cooper
2020-05-30 15:15 ` Lai Jiangshan
2020-05-29 21:27 ` [PATCH 03/14] x86/hw_breakpoint: Prevent data breakpoints on per_cpu cpu_tss_rw Peter Zijlstra
2020-05-29 21:27 ` [PATCH 04/14] x86/hw_breakpoint: Prevent data breakpoints on user_pcid_flush_mask Peter Zijlstra
2020-05-29 21:27 ` [PATCH 05/14] x86/entry: Introduce local_db_{save,restore}() Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 06/14] x86/entry, nmi: Disable #DB Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 07/14] x86/entry, mce: Disallow #DB during #MC Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 08/14] x86/entry: Optimize local_db_save() for virt Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-03 1:17 ` [PATCH 08/14] " Sean Christopherson
2020-05-29 21:27 ` [PATCH 09/14] x86/entry: Remove debug IDT frobbing Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 10/14] x86/entry: Remove DBn stacks Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 11/14] x86/entry: Clarify irq_{enter,exit}_rcu() Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-02 14:42 ` [PATCH 11/14] " Qian Cai
2020-06-02 15:05 ` Peter Zijlstra
2020-06-02 18:47 ` Qian Cai
2020-06-03 17:50 ` [tip: x86/entry] x86/entry: Use __irq_exit_rcu() in irq_exit() tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 12/14] x86/entry: Rename trace_hardirqs_off_prepare() Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` Peter Zijlstra [this message]
2020-05-29 22:14 ` [PATCH 13/14] lockdep: Prepare for NMI IRQ state tracking Steven Rostedt
2020-05-29 22:25 ` Peter Zijlstra
2020-05-29 22:28 ` Steven Rostedt
2020-05-29 22:33 ` Peter Zijlstra
2020-06-02 20:00 ` Peter Zijlstra
2020-05-29 21:27 ` [PATCH 14/14] x86/entry: Fix NMI vs " Peter Zijlstra
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