Messages in this thread | | | Date | Mon, 18 Aug 2008 14:27:14 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: ftrace introduces instability into kernel 2.6.27(-rc2,-rc3) |
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On Mon, 18 Aug 2008, Scott Wood wrote:
> Mathieu Desnoyers wrote: > > asm volatile ( > > "1: lwz %1, 0(%2)\n" > > " cmpw %1, %5\n" > > " bne 2f\n" > > " stwu %3, 0(%2)\n" > > "2:\n" > > ".section .fixup, \"ax\"\n" > > "3: li %0, 1\n" > > " b 2b\n" > > ".previous\n" > > ".section __ex_table,\"a\"\n" > > _ASM_ALIGN "\n" > > _ASM_PTR "1b, 3b\n" > > ".previous" > > : "=r"(faulted), "=r"(replaced) > > : "r"(ip), "r"(new), > > "0"(faulted), "r"(old) > > : "memory"); > > Some (most likely unrelated) nits in the above inline asm:
Thanks,
> > Should use a "b" constraint for %2, or you could get r0.
I will make an updated patch.
> Or, use an "m" > constraint with %U2%X2 after the lwz/stw.
The 'b' seems easier ;-)
> Why stwu with an offset of zero, > BTW?
Because it worked :-) Really, it has been a while since I did any PPC assembly, and I didn't break out the old reference manuals to do this. I simply looked at other asm code, and followed suit. I compiled and tested it, and it worked. I did make a disclaimer about my rusty PPC knowledge when I posted the code.
> > %1 also needs to be an early clobber.
Not exactly sure what you mean by the above.
-- Steve
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