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Date: Wed, 13 Nov 2013 14:58:07 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Will Deacon <will.deacon@arm.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
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Subject: Re: [PATCH RFC 2/6] arm64: Kprobes with single stepping support
Message-ID: <20131113135807.GJ26898@twins.programming.kicks-ass.net>
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On Mon, Nov 11, 2013 at 10:58:12AM +0000, Will Deacon wrote:
> Single-stepping on x86 is different to the step behaviour on arm64 afaik. On
> ARM, we have to manually remove the breakpoint, perform a single-step, then
> add the breakpoint again. If we re-enable debug exceptions in the kprobe
> handler, the step will complete early and we'll never step off the
> breakpoint.

This is about hardware breakpoints right? Which are per-cpu? Otherwise
removing the breakpoint would open up a hole for another thread to slip
through while you're single stepping.