Messages in this thread | | | Date | Fri, 15 Jun 2012 19:52:48 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 11/15] uprobes: move BUG_ON(UPROBE_SWBP_INSN_SIZE) from write_opcode() to install_breakpoint() |
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On 06/15, Srikar Dronamraju wrote: > > > @@ -699,6 +694,10 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, > > if (ret) > > return ret; > > > > + /* write_opcode() assumes we don't cross page boundary */ > > + BUG_ON((uprobe->offset & ~PAGE_MASK) + > > + UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); > > + > > uprobe->flags |= UPROBE_COPY_INSN; > > } > > I am now thinking if we really need a BUG_ON?
I was thinking about this too.
> I am now thinking I should > have had a check at the start in uprobe_register() and failed the request. > > Something like > if ((offset & ~PAGE_MASK) + UPROBE_SWBP_INSN_SIZE > PAGE_SIZE) > return -EINVAL;
Perhaps. Or we can simply remove it. arch_uprobe_analyze_insn() should be careful anyway, and all this validation should be moved into uprobe_register/alloc_uprobe.
I do not really mind, I only wanted to simplify write_opcode() which does a lot of unnecessary things (say, lock_page, I am going to kill it).
So. Do you want me to redo this patch? Or do you think we can keep this "must not happen after arch_uprobe_analyze_insn" check?
Oleg.
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