Abstract out the common functionality for dealing with special sections
into a new kpatch_process_special_sections() function.
The base sections are partitioned into "groups". Only those groups
whose relas reference a changed function are kept. The only difference
in the logic for handling each special section is determining the size
of a given group. Each section has its own group_size() callback for
this. It's a callback instead of an integer because one of the
soon-to-be-supported special sections requires that its group sizes be
dynamically determined.
For a local non-included function or object which is needed by an
included function, its symbol table entry will still refer to a local
section index. Instead it should be changed to SHN_UNDEF.
The -fdata-sections gcc flag doesn't work with objects in the
.data..percpu section. Any function which uses a percpu variable
references this section, causing the section to get incorrectly included
in the patch module.
Manually convert these section references to object symbol references so
that the needed symbol can be found in vmlinux.
Also, the core module symbol verification code will fail when looking up
a percpu variable, because sprint_symbol doesn't think a percpu address
is a valid kernel address. So rewrite the symbol verification code to
use kallsyms_on_each_symbol() instead. It's not ideal performance-wise:
it seems to cost about 1ms per symbol lookup. I think that's acceptable
for now. In the future we may want to try to get a better upstream
kallsyms interface.
Both unpatched and patched objects may contain FILE
symbol with empty name. This is unexpected for
create-diff-object and could correlate 2 symbols
with same (empty) name but different types:
sym 00, type 0, bind 0, ndx 00, name (SAME)
...
sym 425, type 4, bind 0, ndx 65521, name (SAME)
...
signal.o: changed function: do_rt_tgsigqueueinfo
signal.o: changed function: do_rt_sigqueueinfo
signal.o: changed function: get_signal_to_deliver
signal.o: signal.o: changed section .rela__jump_table not selected for inclusion
signal.o: 1 unsupported section change(s)
/root/kpatch/kpatch-build/create-diff-object: unreconcilable difference
Introduce condition to match symbols also by type.
Signed-off-by: Jan Stancek <jstancek@redhat.com>
Combine all the patch modules into a single kpatch-COMBINED.ko for a
much quicker test which still gives 95% or so of the coverage compared
to the full test suite. Use "make quick" for use this new option.
This feature is implemented as:
```
[root@localhost kpatch]# insmod ./kpatch-meminfo.ko
[root@localhost kpatch]# ls /sys/kernel/kpatch/patches/kpatch_meminfo/functions/meminfo_proc_show/
new_addr old_addr
[root@localhost kpatch]# cat /sys/kernel/kpatch/patches/kpatch_meminfo/functions/meminfo_proc_show/new_addr
0xffffffffa05211e0
[root@localhost kpatch]# cat /sys/kernel/kpatch/patches/kpatch_meminfo/functions/meminfo_proc_show/old_addr
0xffffffff8125d0e0
```
The patch module init function will allocate and init kpatch_func_obj with
customized kobj_type func_ktype. The attribute new_addr and old_addr of
kpatch_func_obj is attached to this func_ktype, so that these files could
be created by kobject_add automatically.
Signed-off-by: Jincheng Miao <jincheng.miao@gmail.com>
The inventory based testing for create-diff-object was introduced at a
time when create-diff-object only needed the two object files to operate.
Now, it requires vmlinux as well. This makes the inventory testing (a
unit testing framework for create-diff-object) obsolete and difficult to
update in it's current form.
This commit removes the inventory test framework.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
This commit introduces functionality to verify the location of symbols
used in both the patch and dynrelas sections. It adds significant
protection from mismatches between the base and running kernels.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
Right now the matching criteria for the NULL sym is type LOCAL and shndx
UNDEF. Unfortunately, that would also match any new LOCAL symbol
added to the symbol table with uninit'd sym.* fields i.e. the upcoming
__kpatch_strings and .kpatch.strings symbols.
Change the matching criteria to be symbols that have a zero-length name;
a property unique to the NULL sym.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
kpatch_migrate_included_symbols() is called from
kpatch_reorder_symbols() now, not kpatch_migrate_included_elements().
The difference is the kpatch_reorder_symbols() is operating on the
output kpatch_elf structure, and thus all symbols are by definition
included.
Remove the check and rename the function since it is redundant.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
This fixes the weird ld errors we've been seeing lately.
According to the "ELF-64 Object File Format" spec, the symtab sh_info
field should contain "Index of first non-local symbol (i.e., number of
local symbols)".
Right now, reindexing of the included sections and symbols is done
when they migrate to the output kpatch_elf structure. However, due
to recently added features, the section and symbol list is not
final at this point, leading to constant tracking of the indexes for
addition sections and symbols added after this point. Additionally,
symbols have to be in a particular order, adding to the complexity.
This commit delays the reindexing and symbol reordering until the
section and symbol lists are finalized, removing the need to
track indexes and placeholders in the symbol list.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
Since we only ever have one cache at a time, move the kernel source from
~/.kpatch/$(uname -r)/src to ~/.kpatch/src. This allows ccache to work
between kernel version changes, making it less painful to build for
multiple kernels. The cache's kernel version is stored in
~/.kpatch/version.
The user-installed vs system-installed dichotomy is confusing. Let's
just have "installed". RPM-installed modules can just call "kpatch
install" in their post-install step.
Because create-diff-object is a one-shot program (not a long lived
process) we haven't really bothered with cleaning up and freeing any
allocated memory. However, freeing data when it passes out of the
logical scope does have debugging benefits.
This commit adds two new functions for tearing down and freeing the
primary struct kpatch_elf data structures. The idea is the if a stale
pointer still references the old data structure that has passed out of
the logical scope, an issue will be more immediately apparent (i.e. NULL
references).
Signed-off-by: Seth Jennings <sjenning@redhat.com>
We rebuild the rela section data buffer in kpatch_create_rela_section()
just to rebuild it again later in kpatch_rebuild_rela_section_data()
before writing the output ELF file.
This commit removes the redundant rebuild while retaining the update
for the section header data.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
