linux-toradex.git/include/linux/livepatch.h, branch v4.8-rc1

Merge branches 'for-4.7/core', 'for-4.7/livepatching-doc' and 'for-4.7/livepatching-ppc64' into for-linus

2016-05-17T10:06:35+00:00

livepatch: make object/func-walking helpers more robust

2016-04-29T22:04:08+00:00

Current object-walking helper checks the presence of obj->funcs to
determine the end of objs array in klp_object structure. This is
somewhat fragile because one can easily forget about funcs definition
during livepatch creation. In such a case the livepatch module is
successfully loaded and all objects after the incorrect one are omitted.
This is very confusing. Let's make the helper more robust and check also
for the other external member, name. Thus the helper correctly stops on
an empty item of the array. We need to have a check for obj->funcs in
klp_init_object() to make it work.

The same applies to a func-walking helper.

As a benefit we'll check for new_func member definition during the
livepatch initialization. There is no such check anywhere in the code
now.

[jkosina@suse.cz: fix shortlog]
Signed-off-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Acked-by: Jessica Yu 
Signed-off-by: Jiri Kosina

livepatch: reuse module loader code to write relocations

2016-04-01T13:00:11+00:00

Reuse module loader code to write relocations, thereby eliminating the need
for architecture specific relocation code in livepatch. Specifically, reuse
the apply_relocate_add() function in the module loader to write relocations
instead of duplicating functionality in livepatch's arch-dependent
klp_write_module_reloc() function.

In order to accomplish this, livepatch modules manage their own relocation
sections (marked with the SHF_RELA_LIVEPATCH section flag) and
livepatch-specific symbols (marked with SHN_LIVEPATCH symbol section
index). To apply livepatch relocation sections, livepatch symbols
referenced by relocs are resolved and then apply_relocate_add() is called
to apply those relocations.

In addition, remove x86 livepatch relocation code and the s390
klp_write_module_reloc() function stub. They are no longer needed since
relocation work has been offloaded to module loader.

Lastly, mark the module as a livepatch module so that the module loader
canappropriately identify and initialize it.

Signed-off-by: Jessica Yu 
Reviewed-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Acked-by: Heiko Carstens    # for s390 changes
Signed-off-by: Jiri Kosina

livepatch/module: remove livepatch module notifier

2016-03-17T08:45:10+00:00

Remove the livepatch module notifier in favor of directly enabling and
disabling patches to modules in the module loader. Hard-coding the
function calls ensures that ftrace_module_enable() is run before
klp_module_coming() during module load, and that klp_module_going() is
run before ftrace_release_mod() during module unload. This way, ftrace
and livepatch code is run in the correct order during the module
load/unload sequence without dependence on the module notifier call chain.

Signed-off-by: Jessica Yu 
Reviewed-by: Petr Mladek 
Acked-by: Josh Poimboeuf 
Acked-by: Rusty Russell 
Signed-off-by: Jiri Kosina

klp: remove CONFIG_LIVEPATCH dependency from klp headers

2016-03-06T21:22:10+00:00

There is no need for livepatch.h (generic and arch-specific) to depend
on CONFIG_LIVEPATCH. Remove that superfluous dependency.

Reported-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina

livepatch: add sympos as disambiguator field to klp_reloc

2015-12-03T22:01:27+00:00

In cases of duplicate symbols, sympos will be used to disambiguate instead
of val. By default sympos will be 0, and patching will only succeed if
the symbol is unique. Specifying a positive value will ensure that
occurrence of the symbol in kallsyms for the patched object will be used
for patching if it is valid. For external relocations sympos is not
supported.

Remove klp_verify_callback, klp_verify_args and klp_verify_vmlinux_symbol
as they are no longer used.

From the klp_reloc structure remove val, as it can be refactored as a
local variable in klp_write_object_relocations.

Signed-off-by: Chris J Arges 
Reviewed-by: Petr Mladek 
Acked-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina

livepatch: add old_sympos as disambiguator field to klp_func

2015-12-03T22:01:26+00:00

Currently, patching objects with duplicate symbol names fail because the
creation of the sysfs function directory collides with the previous
attempt. Appending old_addr to the function name is problematic as it
reveals the address of the function being patch to a normal user. Using
the symbol's occurrence in kallsyms to postfix the function name in the
sysfs directory solves the issue of having consistent unique names and
ensuring that the address is not exposed to a normal user.

In addition, using the symbol position as the user's method to disambiguate
symbols instead of addr allows for disambiguating symbols in modules as
well for both function addresses and for relocs. This also simplifies much
of the code. Special handling for kASLR is no longer needed and can be
removed. The klp_find_verify_func_addr function can be replaced by
klp_find_object_symbol, and klp_verify_vmlinux_symbol and its callback can
be removed completely.

In cases of duplicate symbols, old_sympos will be used to disambiguate
instead of old_addr. By default old_sympos will be 0, and patching will
only succeed if the symbol is unique. Specifying a positive value will
ensure that occurrence of the symbol in kallsyms for the patched object
will be used for patching if it is valid.

In addition, make old_addr an internal structure field not to be specified
by the user. Finally, remove klp_find_verify_func_addr as it can be
replaced by klp_find_object_symbol directly.

Support for symbol position disambiguation for relocations is added in the
next patch in this series.

Signed-off-by: Chris J Arges 
Reviewed-by: Petr Mladek 
Acked-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina

livepatch: introduce patch/func-walking helpers

2015-05-19T21:58:43+00:00

klp_for_each_object and klp_for_each_func are now used all over the
code. One need not think what is the proper condition to check in the
for loop now.

Signed-off-by: Jiri Slaby 
Acked-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina

livepatch: make kobject in klp_object statically allocated

2015-05-19T21:56:41+00:00

Make kobj variable (of type struct kobject) statically allocated in
klp_object structure. It will allow us to move in the func-object-patch
hierarchy through kobject links.

The only reason to have it dynamic was to not have empty release
callback in the code. However we have empty callbacks for function and
patch in the code now, so it is no longer valid and the advantage of
static allocation is clear.

Signed-off-by: Miroslav Benes 
Signed-off-by: Jiri Slaby 
Acked-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina

livepatch: remove extern specifier from header files

2015-02-18T19:50:05+00:00

Storage-class specifier 'extern' is redundant in front of the function
declaration. According to the C specification it has the same meaning as
if not present at all. So remove it.

Signed-off-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Reviewed-by: Masami Hiramatsu 
Signed-off-by: Jiri Kosina