Hi Konrad, On 07/04/16 04:49, Konrad Rzeszutek Wilk wrote:
This change demonstrates how to generate an xSplice ELF payload.The idea here is that we want to patch in the hypervisor the 'xen_version_extra' function with an function that will return 'Hello World'. The 'xl info | grep extraversion' will reflect the new value after the patching. To generate this ELF payload file we need: - C code of the new code (xen_hello_world_func.c). - C code generating the .xsplice.funcs structure (xen_hello_world.c) - The address of the old code (xen_extra_version). We retrieve it by using 'nm --defined' on xen-syms. - The size of the new and old code for which we use nm --defined -S on our code and xen-syms respectively. There are two C files and one header files generated during build. One could make this one C file if the size of the newly patched function size was known in advance (or an random value was choosen). There is also a strict order of compiling: 1) xen_hello_world_func.c 2) config.h - extract the size of the new function, the old function and the old function address. 3) xen_hello_world.c - which contains the .xsplice.funcs structure. 4) Link the object files in an xen_hello_world.xsplice file. The use-case is simple: $xen-xsplice load /usr/lib/debug/xen_hello_world.xsplice $xen-xsplice list ID | status ----------------------------------------+------------ xen_hello_world APPLIED $xl info | grep extra xen_extra : Hello World $xen-xsplice revert xen_hello_world Performing revert: completed $xen-xsplice unload xen_hello_world Performing unload: completed $xl info | grep extra xen_extra : -unstable Signed-off-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
For the ARM bits: Acked-by: Julien Grall <julien.gr...@arm.com> Regards, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
