[PATCH] fix dump_trace() when called from NMI
For x86_64 architecture NMI interrupt handler (do_NMI) uses exception stack.
When show_regs() is called from NMI handler then pt_regs is in the bottom of
exception stack (unlike to do_IRQ).
show_regs() passes pointer of the traced stack to the show_trace() function
which points to the bottom of the exception stack. Therefore problem occurs
when try to analyze stack of the interrupted process.
This patch adjusts pointer of the traced stack so as it doesn't point to the
bottom of the exception stack.