Messages in this thread | | | Date | Mon, 08 Aug 2005 10:35:51 -0700 | From | Dave Jiang <> | Subject | Re: x86_64 frame pointer via thread context |
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Dave Jiang wrote: > Jan Engelhardt wrote: > >>>> Am I doing something wrong, or is this intended to be this way on >>>> x86_64, or is something incorrect in the kernel? This method works >>>> fine on i386. Thanks for any help! >>> >>> >>> I just tested your program on SLES9 with updated kernel and RBP >>> looks correct to me. Probably something is wrong with your user space >>> includes or your compiler. >> >> >> >> Note that there is -fomit-frame-pointer which might give different >> results than without the option (or explicitly -fno-omit-frame-pointer). >> >> >> Jan Engelhardt > > > I had somebody else test it on FC4 and he observed the same issue. It > may be timing sensitive? Both platforms tested are em64t based so I'm > not sure if on amd64 platforms it varies or not..... > > And you definitely have to include the -fno-omit-frame-pointer. x86_64 > gcc by default has -fomit-frame-pointer on and without explicitly > stating that you want frame pointer you won't get it in rBP. > > It is possible that userspace or toolchain may be suspect, However, why > is the value bad in kernel space when rBP from pt_regs is dumped? > >
One additional note. The app dumps the rBP for two threads. One looks okay, and the other gives 0xffffffff.
-- Dave
------------------------------------------------------ Dave Jiang Software Engineer Phone: (480) 517-0372 MontaVista Software, Inc. Fax: (480) 517-0262 2141 E Broadway Rd, St 108 Web: www.mvista.com Tempe, AZ 85282 mailto:djiang@mvista.com ------------------------------------------------------
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