NOBITS section may have a non-zero size, however, the have no data and
the data descriptor will have d_buf set to NULL.
This commit fixes as segfault that occurs from trying to compare the
data of such sections.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
There are cases in which the compiler will create symbols with NOTYPE
that map to a non-zero offset inside an .rodata section. In that case, there
may not be a one-to-one relationship between that symbol and section as
the section may contains the data for multiple NOTYPE symbols.
This commit checks for this case and does not assign the symbol pointer of the
section that contains its data to avoid multiple symbols referring to the same
section from overwriting one another. It also adds a check ensuring that all
symbols whose type is !NOTYPE start at offset 0 within the section. This
should be guarenteed by the -ffunction-sections and -fdata-sections options
compiler options.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
This makes it somewhat easy to use. From the root git dir, just:
sudo scripts/kpatch-build ~/foo.patch
and it'll take care of everything, eventually spitting out the base
module (kpatch.ko) and the hotpatch module kpatch-foo.ko.
This is still all very crude, but a better user interface is coming
soon.
This changes the way the trampoline code works, thanks to a suggestion
by Steve Rostedt. Before, the trampoline was mucking with the stack
pointer and other registers, and jumping to the new function directly.
With this change, all it does is set regs->ip to the address of the new
function and return back to ftrace. When ftrace returns, it will return
to the beginning of the new function.
- fix real issue with 0's in the middle of a merged section (wrong
alignment)
- show patch util output in case it asks a question so it doesn't
silently fail
- fix issue with relocation of local objects (because they become global
objects)
- allow changes to .rela.initcall*. they should be instead caught by
the relocation comparison code.
- fix issue in compare symbols when the symbol section index has changed
but the sections themselves are the same
- in compare_symbols, when a new STT_SECTION symbol is added, ignore it.
it will be caught instead by the section comparison code
- fix issue in kpatch-gcc script that was causing gcc command lines
containing quotes to fail
The end-to-end patching works. From object analysis to generation to
runtime patching. It's still missing the scripting piece that will only
take a patch and kernel source dir as input.
