linux-kernel - [tip: objtool/urgent] locking/lockdep: Improve noinstr vs errors

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Date:   Tue, 22 Jun 2021 12:03:37 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: objtool/urgent] locking/lockdep: Improve noinstr vs errors

The following commit has been merged into the objtool/urgent branch of tip:

Commit-ID:     49faa77759b211fff344898edc23bb780707fff5
Gitweb:        https://git.kernel.org/tip/49faa77759b211fff344898edc23bb780707fff5
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Mon, 21 Jun 2021 13:12:38 +02:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Tue, 22 Jun 2021 13:56:43 +02:00

locking/lockdep: Improve noinstr vs errors

Better handle the failure paths.

  vmlinux.o: warning: objtool: debug_locks_off()+0x23: call to console_verbose() leaves .noinstr.text section
  vmlinux.o: warning: objtool: debug_locks_off()+0x19: call to __kasan_check_write() leaves .noinstr.text section

  debug_locks_off+0x19/0x40:
  instrument_atomic_write at include/linux/instrumented.h:86
  (inlined by) __debug_locks_off at include/linux/debug_locks.h:17
  (inlined by) debug_locks_off at lib/debug_locks.c:41

Fixes: 6eebad1ad303 ("lockdep: __always_inline more for noinstr")
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Link: https://lore.kernel.org/r/20210621120120.784404944@infradead.org
---
 include/linux/debug_locks.h | 2 ++
 kernel/locking/lockdep.c    | 4 +++-
 lib/debug_locks.c           | 2 +-
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/linux/debug_locks.h b/include/linux/debug_locks.h
index 2915f56..edb5c18 100644
--- a/include/linux/debug_locks.h
+++ b/include/linux/debug_locks.h
@@ -27,8 +27,10 @@ extern int debug_locks_off(void);
 	int __ret = 0;							\
 									\
 	if (!oops_in_progress && unlikely(c)) {				\
+		instrumentation_begin();				\
 		if (debug_locks_off() && !debug_locks_silent)		\
 			WARN(1, "DEBUG_LOCKS_WARN_ON(%s)", #c);		\
+		instrumentation_end();					\
 		__ret = 1;						\
 	}								\
 	__ret;								\
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 7641bd4..e323130 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -843,7 +843,7 @@ static int count_matching_names(struct lock_class *new_class)
 }
 
 /* used from NMI context -- must be lockless */
-static __always_inline struct lock_class *
+static noinstr struct lock_class *
 look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
 {
 	struct lockdep_subclass_key *key;
@@ -851,12 +851,14 @@ look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
 	struct lock_class *class;
 
 	if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
+		instrumentation_begin();
 		debug_locks_off();
 		printk(KERN_ERR
 			"BUG: looking up invalid subclass: %u\n", subclass);
 		printk(KERN_ERR
 			"turning off the locking correctness validator.\n");
 		dump_stack();
+		instrumentation_end();
 		return NULL;
 	}
 
diff --git a/lib/debug_locks.c b/lib/debug_locks.c
index 06d3135..a75ee30 100644
--- a/lib/debug_locks.c
+++ b/lib/debug_locks.c
@@ -36,7 +36,7 @@ EXPORT_SYMBOL_GPL(debug_locks_silent);
 /*
  * Generic 'turn off all lock debugging' function:
  */
-noinstr int debug_locks_off(void)
+int debug_locks_off(void)
 {
 	if (debug_locks && __debug_locks_off()) {
 		if (!debug_locks_silent) {