On Mon 2015-11-09 23:45:53, Jessica Yu wrote:
> Reuse module loader code to write relocations, thereby eliminating the
> need for architecture specific code in livepatch. Namely, we reuse
> apply_relocate_add() in the module loader to write relocs instead of
> duplicating functionality in livepatch's klp_write_module_reloc(). To
> apply relocation sections, remaining SHN_LIVEPATCH symbols referenced by
> relocs are resolved and then apply_relocate_add() is called to apply
> those relocations.
>
> Signed-off-by: Jessica Yu <jeyu@xxxxxxxxxx>
> ---
> include/linux/livepatch.h | 11 ++++--
> include/linux/module.h | 6 ++++
> kernel/livepatch/core.c | 89 +++++++++++++++++++++++++++++------------------
> 3 files changed, 70 insertions(+), 36 deletions(-)
>
> index 087a8c7..26c419f 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -28,6 +28,8 @@
> #include <linux/list.h>
> #include <linux/kallsyms.h>
> #include <linux/livepatch.h>
> +#include <linux/elf.h>
> +#include <asm/cacheflush.h>
>
> /**
> * struct klp_ops - structure for tracking registered ftrace ops structs
> @@ -281,46 +283,54 @@ static int klp_find_external_symbol(struct module *pmod, const char *name,
> }
>
> static int klp_write_object_relocations(struct module *pmod,
> - struct klp_object *obj)
> + struct klp_object *obj,
> + struct klp_patch *patch)
> {
[...]
> +
> + /* For each __klp_rela section for this object */
> + list_for_each_entry(reloc_sec, &obj->reloc_secs, list) {
Who, when, and how will define reloc_secs, please?
I guess that it is just an optimization. It helps to avoid going
through all elf sections of all livepatch modules. Therefore, I think
that we might fill this when the livepatch module is loaded. But
I do not see the code for this.
Best Regards,
Petr
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