On 09/24, Oleg Nesterov wrote:
>
> Anyway,
>
> > for example
> > 0f 1f 40 00
>
> OK, thanks, objdump reports "nopl 0x0(%rax)", looks fine.
>
> But. I do not see how __skip_sstep() can handle this case correctly.
> Not only it should update regs->ip afaics, it should also account 2
> extra bytes _af
Srikar, sorry for delay, somehow I missed this email.
And I am still confused...
On 09/20, Srikar Dronamraju wrote:
>
> * Oleg Nesterov [2012-09-18 18:07:38]:
>
> > > > I compiled this program
> > > >
> > > > int main(void)
> > > > {
> > > > asm volatile (".word 0
* Oleg Nesterov [2012-09-18 18:07:38]:
> >
> > > Probably this is fine, at least this is
> > > fine if it finds "nop" eventually. But I can't undestand what
> > > "0x66* { 0x90 | 0x0f 0x1f | 0x0f 0x19 | 0x87 0xc0 }" means.
> > > OK, 0x66 and 0x90 are clear. But, say, 0x0f 0x1f ?
> >
> > we skip i
* Oleg Nesterov [2012-09-14 19:15:57]:
> If handle_swbp()->add_utask() fails but UPROBE_SKIP_SSTEP is set,
> cleanup_ret: path do not restart the insn, this is wrong. Remove
> this check and add the additional label for can_skip_sstep() = T
> case.
>
> Note also that UPROBE_SKIP_SSTEP can be fal
On 09/17, Srikar Dronamraju wrote:
>
> * Oleg Nesterov [2012-09-15 17:01:20]:
>
> > Off-topic question... I am trying to understand if arch_uprobe_skip_sstep()
> > is correct on x86.
> >
> > It doesn't update regs->ip.
>
> Right. we need to adjust for the size of the instruction.
>
> > Probably th
* Oleg Nesterov [2012-09-15 17:01:20]:
> On 09/15, Ananth N Mavinakayanahalli wrote:
> >
> > On Fri, Sep 14, 2012 at 07:15:57PM +0200, Oleg Nesterov wrote:
> > >
> > > Note: probably we should rename "skip" to "emulate" and I think
> > > that "clear UPROBE_SKIP_SSTEP" should be moved to arch_can_
On 09/15, Ananth N Mavinakayanahalli wrote:
>
> On Fri, Sep 14, 2012 at 07:15:57PM +0200, Oleg Nesterov wrote:
> >
> > Note: probably we should rename "skip" to "emulate" and I think
> > that "clear UPROBE_SKIP_SSTEP" should be moved to arch_can_skip.
>
> Agree. emulate is more accurate in this sit
On Fri, Sep 14, 2012 at 07:15:57PM +0200, Oleg Nesterov wrote:
> If handle_swbp()->add_utask() fails but UPROBE_SKIP_SSTEP is set,
> cleanup_ret: path do not restart the insn, this is wrong. Remove
> this check and add the additional label for can_skip_sstep() = T
> case.
>
> Note also that UPROBE
If handle_swbp()->add_utask() fails but UPROBE_SKIP_SSTEP is set,
cleanup_ret: path do not restart the insn, this is wrong. Remove
this check and add the additional label for can_skip_sstep() = T
case.
Note also that UPROBE_SKIP_SSTEP can be false positive, we simply
can not trust it unless arch_u
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