Messages in this thread | | | Date | Wed, 5 Oct 2011 19:53:53 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH v5 3.1.0-rc4-tip 5/26] Uprobes: copy of the original instruction. |
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On 10/05, Srikar Dronamraju wrote: > > * Oleg Nesterov <oleg@redhat.com> [2011-10-03 18:29:05]: > > > But I am starting to think I simply do not understand this change. > > To the point, I do not underestand why do we need copy_insn() at all. > > We are going to replace this page, can't we save/analyze ->insn later > > when we copy the content of the old page? Most probably I missed > > something simple... > > > > Copying the instruction at the time we replace the original instruction > would have been ideal. However there are a few irritants to handle. > > ... > How do we distinguish if the > breakpoint instruction was around in the text or somebody inserted a > breakpoint in that address-space? Since we read from the page-cache, > we can easily resolve this.
Ah. I see.
> - On archs like x86, with variable size instructions, the original > instruction can be across 2 pages.
Heh. Indeed ;)
Thanks Srikar.
Oleg.
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