Messages in this thread | | | Subject | Re: [PATCH -v4 9/9] tracing: add function graph tracer support for MIPS | From | Steven Rostedt <> | Date | Thu, 22 Oct 2009 11:20:22 -0400 |
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On Thu, 2009-10-22 at 21:31 +0800, Wu Zhangjin wrote:
> > If we don't stop at just one save, but look for the saving of ra, it > > should not fail. > > > > We can not look for the saving of ra continuously(when should we stop?
When we hit something other than sw .... I'm sure we will get to something other than a store. ;-)
> if with -fno-omit-fram-pointer, we have "move s8,sp" or "addiu sp, sp, > -offset", but without it, we have no "guideboard" to know that is the > beginning of the function!), 'Cause we may find the saving of ra of > another function, which will fail at that time.
But that other function should have a jump to mcount before it, or some other kind of return. A function that has _mcount attached, can not be inlined. So something must have jumped to it. There should be no cases where code from above just "falls" into the leaf function.
> > BTW: Just replace probe_kernel_read() and tracing_stop/tracing_start by > asm, it works in 32bit, but fails in 64bit, I'm trying to find why!(TLB > miss on load or ifetch, will fix it asap! and resend the patchset out!)
Thanks!
-- Steve
Note, I'm going to try booting a vanilla kernel on the notebook. If it works, I'll start applying your patches and playing with it too. But I also have some other work to do first.
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