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From: Peter Zijlstra <peterz@infradead.org>
To: mhiramat@kernel.org
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
	mingo@kernel.org, rostedt@goodmis.org,
	naveen.n.rao@linux.vnet.ibm.com, ananth@linux.ibm.com,
	x86@kernel.org
Subject: [PATCH 0/2] kprobes: Remove kprobe::fault_handler
Date: Tue, 25 May 2021 09:25:18 +0200	[thread overview]
Message-ID: <20210525072518.791889911@infradead.org> (raw)

The reason for kprobe::fault_handler(), as given by their comment:

* We come here because instructions in the pre/post
* handler caused the page_fault, this could happen
* if handler tries to access user space by
* copy_from_user(), get_user() etc. Let the
* user-specified handler try to fix it first.

Is just plain bad. Those other handlers are ran from non-preemptible
context and had better use _nofault() functions. Also, there is no
upstream usage of this.

The corollary of this change is that no tracing/probing/whatever can consume
faults.


             reply	other threads:[~2021-05-25  7:33 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-25  7:25 Peter Zijlstra [this message]
2021-05-25  7:25 ` [PATCH 1/2] " Peter Zijlstra
2021-05-25 14:06   ` Masami Hiramatsu
2021-05-26 10:50   ` Naveen N. Rao
2021-05-26 13:51     ` Masami Hiramatsu
2021-06-01 12:01   ` [PATCH] kprobes: Do not increment probe miss count in the fault handler Naveen N. Rao
2021-06-01 13:20     ` Peter Zijlstra
2021-06-01 23:48       ` Masami Hiramatsu
2021-06-04 13:38     ` [tip: perf/core] " tip-bot2 for Naveen N. Rao
2021-06-01 14:04   ` [tip: perf/core] kprobes: Remove kprobe::fault_handler tip-bot2 for Peter Zijlstra
2021-05-25  7:25 ` [PATCH 2/2] x86,kprobes: WARN if kprobes tries to handle a fault Peter Zijlstra
2021-05-25 14:21   ` Masami Hiramatsu
2021-06-01 14:04   ` [tip: perf/core] " tip-bot2 for Peter Zijlstra

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