Thanks to David for his help in tracking it down.

  compile the kernel with sibling call optimization
  turned off. There is a problem with all functions
  using the optimization and the asmlinkage attribute.
  The compiler should not perform the optimization on
  these functions because it cannot preserve the syscall
  parameters in the callee. This caused SIGSEGV on programs
  traced with PTRACE_SYSCALL, for instance.
signed-off-by: stephane eranian <eranian@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>