This is a text provided by Udo and polished. Signed-off-by: Jiri Slaby <jsl...@suse.cz> Cc: Udo Seidel <udosei...@gmx.de> --- Documentation/kgraft.txt | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 Documentation/kgraft.txt
diff --git a/Documentation/kgraft.txt b/Documentation/kgraft.txt new file mode 100644 index 000000000000..476beaf35c62 --- /dev/null +++ b/Documentation/kgraft.txt @@ -0,0 +1,44 @@ +Live Kernel Patching with kGraft +-------------------------------- + +Written by Udo Seidel <udoseidel at gmx dot de> +Based on the Blog entry by Vojtech Pavlik +Updated by Jiri Slaby + +June 2014 + +kGraft's developement was started by the SUSE Labs. kGraft builds on +technologies and ideas that are already present in the kernel: ftrace [1] and +its mcount-based reserved space in function headers [2], the INT3/IPI-NMI +patching also used in jump labels [3], and RCU-like update of code that does +not require stopping the kernel. + +A kGraft patch is a kernel module and fully relies on the in-kernel module +loader to link the new code with the kernel. Thanks to all that, the design +can be nicely minimalistic. + +While kGraft is, by choice, limited to replacing whole functions and constants +they reference, this does not limit the set of code patches that can be +applied significantly. + +Use +--- + +1) Build a kernel with CONFIG_KGRAFT enabled +2) Create a module with a patch + * Look at samples/kgraft/kgraft_patcher.c for an example +3) Insert the module from 2) into the booted kernel from 1) +4) All processes need to enter the kernel to acknowledge the new state + * This can be done e.g. by sending a non-fatal signal to all processes + * Check /proc/*/kgr_in_progress to check who still needs to be poked +5) You should see "kgr succeeded" in dmesg now + +Enjoy your patched system! + + +References +---------- + +[1] Documentation/trace/ftrace.txt +[2] Documentation/trace/ftrace-design.txt +[3] Documentation/static-keys.txt -- 2.0.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/