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kpatch/kmod/patch/kpatch.lds

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implement per-object patching/relocations The recent module patching code has exposed some problems with our data structures. We currently patch the funcs and dynrelas individually, which is kind of scary now that different objects can be patched at different times. Instead it's cleaner and safer to group them by patched object. This patch implements per-object patching and relocations by refactoring the interfaces: - Completely separate the create-diff-object <-> patch module interface from the patch module <-> core module interface. create-diff-object will include "kpatch-patch.h" but not "kpatch.h". Thus, create-diff-object has no knowledge about the core module's interfaces, and the core module has no knowledge about the patch module's special sections. - Newly added kpatch-patch.h defines the format of the patch module special sections. It's used by create-diff-object to create the special sections and used by the patch module to read them. - kpatch.h still defines the core module interfaces. Each kpatch_module has a list of kpatch_objects for each module object to be patched. Each kpatch_object has a list of kpatch_funcs and a list of kpatch_dynrelas. The patch module creates these lists when populating kpatch_module. This way of structuring the data allows us to patch funcs and dynrelas on a per patched object basis, which will allow us to catch more error scenarios and make the code easier to manage going forward. It also allows the use of much more common code between kpatch_register() and kpatch_module_notify().
2014-06-17 14:51:47 +00:00
__kpatch_funcs = ADDR(.kpatch.funcs);
__kpatch_funcs_end = ADDR(.kpatch.funcs) + SIZEOF(.kpatch.funcs);
dynrelas support, obsoleting link-vmlinux-syms This adds dynamic linking support for the patch modules. It is the first step toward supporting patching module code and relocatable kernels. Rela entries that reference non-included local and non-exported global symbols are converted to "dynrelas". These dynrelas are relocations that are done by the core module, not the kernel module linker. This allows the core module to apply offsets to the base addresses found in the base vmlinux or module. Signed-off-by: Seth Jennings <sjenning@redhat.com> Conflicts: kpatch-build/kpatch-build
2014-05-14 20:59:05 +00:00
__kpatch_dynrelas = ADDR(.kpatch.dynrelas);
__kpatch_dynrelas_end = ADDR(.kpatch.dynrelas) + SIZEOF(.kpatch.dynrelas);
add user-defined load/unload hook support This commit enables the ability to create user-defined hooks as part of the normal code patch that can do preparatory work for the application of the patch. This work could include, but is not limited to, changing data structure semantics. The user may define a new function as part of the patch and mark it as a load-time or unload-time hook with the kpatch_load_hook() and kpatch_unload_hook() macros. These macros are in an include file that gets copied into the source tree at include/linux/kpatch-hooks.h at patch build time. The signature for both hooks is "int kpatch_unload_hook(void)". For now, the return code is ignored. The hooks may not fail. They also run in stop_machine() context and may not sleep. These hooks, more or less, must follow all the rules of interrupt context code.
2014-06-27 17:01:39 +00:00
SECTIONS
{
.kpatch.hooks.load : {
__kpatch_hooks_load = . ;
*(.kpatch.hooks.load)
__kpatch_hooks_load_end = . ;
QUAD(0);
}
.kpatch.hooks.unload : {
__kpatch_hooks_unload = . ;
*(.kpatch.hooks.unload)
__kpatch_hooks_unload_end = . ;
QUAD(0);
}
}