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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org
Cc: Dmitry Vyukov <dvyukov@google.com>,
	Andrey Konovalov <andreyknvl@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Steven Rostedt <rostedt@goodmis.org>,
	Marco Elver <elver@google.com>,
	Clark Williams <williams@redhat.com>
Subject: [PATCH 0/5] kcov: PREEMPT_RT fixup + misc
Date: Mon, 30 Aug 2021 19:26:22 +0200	[thread overview]
Message-ID: <20210830172627.267989-1-bigeasy@linutronix.de> (raw)

The last patch in series is follow-up to address the PREEMPT_RT issue
within in kcov reported by Clark [0].
Patches 1-3 are smaller things that I noticed while staring at it.
Patch 4 is small change which makes replacement in #5 simpler / more
obvious.
I tested this with the three examples in the documentation folder and I
didn't notice higher latency with kcov enabled. Debug or not, I don't
see a reason to make the lock a raw_spin_lock_t annd it would complicate
memory allocation as mentioned in #5.

One thing I noticed and have no idea if this is right or not:
The code seems to mix long and uint64_t for the reported instruction
pointer / position in the buffer. For instance
__sanitizer_cov_trace_pc() refers to a 64bit pointer (in the comment)
while the area pointer itself is (long *). The problematic part is that
a 32bit application on a 64bit pointer will expect a four byte pointer
while kernel uses an eight byte pointer.

[0] https://lkml.kernel.org/r/20210809155909.333073de@theseus.lan

Sebastian



             reply	other threads:[~2021-08-30 17:26 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-30 17:26 Sebastian Andrzej Siewior [this message]
2021-08-30 17:26 ` [PATCH 1/5] Documentation/kcov: Include types.h in the example Sebastian Andrzej Siewior
2021-09-17 14:34   ` Dmitry Vyukov
2021-08-30 17:26 ` [PATCH 2/5] Documentation/kcov: Define `ip' " Sebastian Andrzej Siewior
2021-09-17 14:37   ` Dmitry Vyukov
2021-08-30 17:26 ` [PATCH 3/5] kcov: Allocate per-CPU memory on the relevant node Sebastian Andrzej Siewior
2021-09-17 14:38   ` Dmitry Vyukov
2021-08-30 17:26 ` [PATCH 4/5] kcov: Avoid enable+disable interrupts if !in_task() Sebastian Andrzej Siewior
2021-09-17 14:50   ` Dmitry Vyukov
2021-08-30 17:26 ` [PATCH 5/5] kcov: Replace local_irq_save() with a local_lock_t Sebastian Andrzej Siewior
2021-09-17 14:58   ` Dmitry Vyukov
2021-09-06 16:13 ` [PATCH 0/5] kcov: PREEMPT_RT fixup + misc Marco Elver
2021-09-06 16:28   ` Sebastian Andrzej Siewior
2021-09-20  9:26     ` Marco Elver
2021-09-20  9:50       ` Sebastian Andrzej Siewior

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