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SubjectRe: ftrace introduces instability into kernel 2.6.27(-rc2,-rc3)
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:

Should use a "b" constraint for %2, or you could get r0. Or, use an "m"
constraint with %U2%X2 after the lwz/stw. Why stwu with an offset of
zero, BTW?
%1 also needs to be an early clobber.

-Scott


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