Scott Wood wrote: > On Sat, 16 Jul 2011 03:25:47 +0000 > "Chen, Tiejun" <tiejun.c...@windriver.com> wrote: > >>> -----Original Message----- >>> From: Scott Wood [mailto:scottw...@freescale.com] >>> Sent: Saturday, July 16, 2011 2:43 AM >>> To: Chen, Tiejun >>> Cc: Kumar Gala; linuxppc-...@ozlabs.org >>> Subject: Re: [v3 PATCH 1/1] booke/kprobe: make program >>> exception to use one dedicated exception stack >>> >>> On Fri, 15 Jul 2011 13:28:15 +0800 >>> tiejun.chen <tiejun.c...@windriver.com> wrote: >>> >>>> Kumar Gala wrote: >>>>> I'm still very confused why we need a unique stack frame >>> for kprobe/program exceptions on book-e devices. >>>> Its a bug at least for Book-E. >>> But why only booke? There's nothing booke-specific about the >> I don't mean this is reproduced only on booke, so I use 'at least' carefully >> to notice we really see this problem on booke. >> >>> stwu instruction. >> Please note this root cause to this bug is not related to how to emulate >> stwu instruction. That should be issued from the overlap between an >> exception frame and the kprobed function stack frame on booke. Would you >> like to see that example I showed? > > As I understand it, the problem comes from the fact that stwu combines the > creation of a stack frame with storing into that stack frame. If they were
Yes. > separate instructions you'd have a new exception frame at a lower address > by the time you actually store to the non-exception frame. So when kprobe we should use a unique stack frame to skip that stack frame the kprobed stwu want to create. Tiejun > > -Scott > > _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
