[Crash-utility] [PATCH] Read in .debug_frame section of vmlinux

Hi Dave and all, The attached patch read the .debug_frame section of vmlinux into crash. By doing this, we could backtrace kernel stack frame using dwarf unwind information contained in that section. ChangeLog: - Modified section_header_info() function to initialize the offset and size of .debug_frame section. - Modified init_unwind_table() function to read in .debug_frame. - Modified the prototype of unwind(), adding a int argument to indicate whether .eh_frame or .debug_frame is used. Also there're a few changes due to the difference between these two sections. Well, it's the first time I came to crash utility, and I hope that I didn't do anything wrong. Thanks, Wang Chao