The naming of variables in this function is confusing, and really threw
me for a loop: sec is first used as an iterator, then sec is reused to
point to the dynrela section, then sec2 is used as another iterator.
Instead make sec the iterator for both loops and dynsec the dynrela
section pointer.
When a function foo.isra.1 has a switch statement, it might have a
corresponding .rodata.foo.isra.1 section (in addition to its
.text.foo.isra.1 section). If so, rename that section too.
Otherwise kpatch-build will get confused when comparing the function's
relas which reference the .rodata section, and will mark the function's
rela section as changed because the rela symbol names differ.
I found this bug when trying to build the patch from upstream Linux
commit a3c54931. Unfortunately this issue is already fixed on F20 and I
wasn't able to come up with a similarly failing test case for the
integration test suite.
When the argument is a .ko file, it should be considered a path (i.e.
don't even look for it in the installed DB). When the argument is a
module name, it should be considered a loaded or installed module (and
then in the case of kpatch load we have to do a reverse translation of
all installed modules to see if any of them match).
Signed-off-by: Seth Jennings <sjenning@redhat.com>
To reduce redundancy, remove/change the old_offset fields in the
kpatch_func and kpatch_patch_func structs to just old_addr. Since
old_offset is being used as a placeholder for old_addr, might as well
consolidate it to just one variable.
Fix incorrect old_offsets for loadable modules during sysfs
initialization in patch_init.
sysfs will be initialized on patch module init regardless of whether
or not the module is loaded. func_old_addr_show() will read from func->old_addr,
which is initially set to 0; it'll be eventually filled in by the core module.
In kpatch_create_dynamic_rela_sections() the dest field is filled in
with either the function symbol or the section symbol that contains the
function depending on whether or not the sym field of the base section
is NULL or not (around line 2153).
In the case of the hook functions, we strip the FUNC symbol to prevent
it from being added to the kpatch.funcs section as a patched function.
However we weren't unbundling the stripped symbol from the section.
This resulted in the sym field pointing to the null symbol (index 0),
corrupting the dynrelas rela section.
Before:
Relocation section [14] '.rela.kpatch.dynrelas' for section [13] '.kpatch.dynrelas' at offset 0x8b8 contains 6 entries:
Offset Type Value Addend Name
000000000000000000 X86_64_64 000000000000000000 +9
0x0000000000000018 X86_64_64 000000000000000000 +8 .kpatch.strings
0x0000000000000020 X86_64_64 000000000000000000 +0 .kpatch.strings
0x0000000000000030 X86_64_64 000000000000000000 +9
0x0000000000000048 X86_64_64 000000000000000000 +8 .kpatch.strings
0x0000000000000050 X86_64_64 000000000000000000 +0 .kpatch.strings
This commit unbundles the stripped symbol from the section so that the
section symbol is used in the dynrelas rela section.
After:
Relocation section [14] '.rela.kpatch.dynrelas' for section [13] '.kpatch.dynrelas' at offset 0x8b8 contains 6 entries:
Offset Type Value Addend Name
000000000000000000 X86_64_64 000000000000000000 +9 .text.kpatch_load_aio_max_nr
0x0000000000000018 X86_64_64 000000000000000000 +8 .kpatch.strings
0x0000000000000020 X86_64_64 000000000000000000 +0 .kpatch.strings
0x0000000000000030 X86_64_64 000000000000000000 +9 .text.kpatch_unload_aio_max_nr
0x0000000000000048 X86_64_64 000000000000000000 +8 .kpatch.strings
0x0000000000000050 X86_64_64 000000000000000000 +0 .kpatch.strings
Signed-off-by: Seth Jennings <sjenning@redhat.com>
On RHEL 7 I see the following error when trying to patch meminfo.o:
cp: cannot stat ‘/home/user/.kpatch/obj/fs/proc/.tmp_meminfo.o’: No such file or directory
It turns out that on RHEL 7, a given object foo.o is compiled as
.tmp_foo.o before then being linked as foo.o. I have no idea why. The
fix is to record .tmp_foo.o as foo.o in the changed_objs file.
The purpose of this test script is to determine if create-diff-object
can properly recognize object file equivalence when passed the same file
for both the original and patched objects. This verifies that
create-diff-object is correctly parsing, correlating, and comparing the
different elements of the object file. In practice, a situation similar
to the test case occurs when a commonly included header file changes,
causing Make to rebuild many objects that have no functional change.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
GROUP section are rare and are a mechanism in the ELF to indicated that
certain groups of section must be included or excluded (stripped)
together.
It is valid to have more than one of these section with the same
".group" name. This currently messes up the section correlation code
with correlates based solely on name.
This commit adds additional correlation criteria for GROUP sections;
namely, the section content must be the same. Changing of groups
sections (i.e. reindexing of the section indexes the GROUP section
includes in their section data) is not supported and will result in a
"new/changed section not included" error.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
The FILES variable can contain unchanged objects, so don't use it to
determine which objects to link. Instead, just use all the objects that
were placed in the output directory by create-diff-object.
There are situations in which an object may be rebuilt but have no
functional changes, such as a change to an included header file.
This commit changes kpatch-build to tolerate individual unchanged
objects so long as there is, in the end, at least one changed object.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
