It turns out this is a more general issue which exists for more than
just CSWTCH symbols. The new static local handling code will handle it.
This reverts commit fd0c1bbe9c.
create-diff-object now checks if the original functions have fentry calls.
If an original function to be affected by the patch does not have the
fentry call, it cannot be patched. Error is reported in that case.
kpatch_create_mcount_sections() now also takes into account if a changed
or a new function has fentry call. If it does, mcount record is
generated for it as before. If a changed or a new function has no fentry
call, it is not an error in this case.
All this fixes the following issues.
1. If an original function has no fentry call (e.g. a "notrace" function)
but the patched function has it, the original function can not be
patched, but it would only be detected when applying the patch.
2. kpatch_create_mcount_sections() crashed if a patched function had no
relocation at all.
I observed such crashes when experimenting with a modified version of
the patch "tcp_cubic: better follow cubic curve after idle period" in
CentOS 7 x64.
Besides that, for a function with the first instruction starting with
0x0f, it would be incorrectly detemined that the function had fentry call.
The first bytes of the function would be overwritten in that case.
3. create-diff-object output an error if a new (an added) function had
no fentry call. This restriction is not necessary.
v2:
* Moved the check for fentry calls after the call to
kpatch_compare_correlated_elements() and before info about the original
ELF file is destroyed. The original symbols are now checked there (via
sym->twin) rather than the patched ones.
* Removed an excessive error check.
Signed-off-by: Evgenii Shatokhin <eshatokhin@odin.com>
Build artifacts are stored in $CACHEDIR/tmp instead of /tmp. This includes
files such as the build log and the temp directories used to build the patch.
In addition, allow $CACHEDIR to be set as an environment variable.
Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
Hard-coding the special section group sizes is unreliable. Instead,
determine them dynamically by finding the related struct definitions in
the DWARF metadata.
Fixes#517.
Fixes#523.
Create a "make remote" target and a poor man's ansible to allow setting
up a remote F22 system and running integration tests on it.
To run tests remotely:
make remote SSH_HOST=my.remote.f22.box
The integration tests are targeted for Fedora kernels, so move them to a
new f22 directory. The README file specifies the exact kernel version
they're targeted for.
-ffunction-sections and -fdata-sections are needed when building the
original and the patched kernels.
It is not necessary, however, to use these options when building a
patch module itself, its functions and data are OK in the sections they
are.
Let us remove these options from KCGLAGS after the kernels have been
built.
If a source RPM is used to obtain the kernel sources, kpatch-build
executes rpmdev-setuptree to prepare ~/rpmbuild directory tree, installs
the source RPM there. Then it calls 'rpmbuild -bp' to prepare the
kernel source tree.
All this, however, may clobber the existing contents of ~/rpmbuild,
which is very inconvenient if one uses rpmbuild to build other packages.
To avoid that, I could not find a better way than to specify a fake home
directory (~/.kpatch/tempsrc) for that portion of kpatch-build. It seems,
neither rpmdev-setuptree nor rpm have appropriate options for that.
I put the affected commands into a subshell so that the changes in $HOME
could not propagate to other parts of kpatch-build.
If kpatch core module is packaged in an RPM and the package is installed,
the likely location of the module and its symvers file is
/lib/modules/<kernel_version>/extra/kpatch/.
kpatch-build checks this location too now when looking for the .symvers
file. This is convenient for distributing the Kpatch tools as RPMs and
the like.
Signed-off-by: Evgenii Shatokhin <eshatokhin@odin.com>
Before this fix, kpatch-build looked for Module.symvers for the core
module built for the currently running kernel. So, if one tried to build
a patch module for a kernel, different from the current one, an error
would occur. This patch fixed the problem.
Signed-off-by: Evgenii Shatokhin <eshatokhin@odin.com>
Before this patch, if changed function is weak symbol, it is not
be allowed to create live patch, and it will trigger the following
error:
/usr/local/libexec/kpatch/create-diff-object: ERROR: ***.o:
kpatch_create_patches_sections: 2294: lookup_global_symbol ***
And if the changed function reference the weak symbol, when loading
the patch module will trigger the following error:
module kpatch-***: overflow in relocation type *** val 0
insmod: can't insert 'kpatch-***.ko': invalid module format
This patch fix it and add support for patching weak function.
Signed-off-by: Li Bin <huawei.libin@huawei.com>
Fixes issue #494. A null pointer dereference can result with patch
modules for multiple objects since the "vmlinux" patch object's "name"
field is null. strcmp therefore crashes trying to compare object->name
if the current object is vmlinux and the supplied "name" argument is
not. Check that object->name is not null before invoking strcmp.
kpatch_verify_patchability can detect the change of .bss or .data or
.init section, but it must be processed before verify num_changed.
Otherwise, for example, if only .init section changed, it will fail
with 'no changed functions were found', but not 'unsupported section
change(s)'.
With this patch,
for .init section: .init section will not a bundled section, so if
the section changed, not sync the function status, kpatch_verify_patchability
will give 'changed section <secname> not selected for inclusion' and
'unsupported section change(s)' error.
for .bss/.data section: kpatch_verify_patchability will ensure not
including .data or .bss section, otherwise it will give 'data section
<secname> selected for inclusion' and 'unsupported section change(s)'
error.
Signed-off-by: Li Bin <huawei.libin@huawei.com>
The shadow_get function does't consider the case that
'shadow is inpace', and after the shadow->data be set to the data,
it will not be the pointer. This patch fix it.
Signed-off-by: Li Bin <huawei.libin@huawei.com>
examples/tcp_cubic-better-follow-cubic-curve-original.patch is the
original patch, combined from two mainline commits (see the description
in the patch). It cannot be used with Kpatch as it is because the
change is in the initialization of a global structure.
examples/tcp_cubic-better-follow-cubic-curve-converted.patch is a
modification of the patch that Kpatch can process. Still, this
modification has its issues, see the description there.
Signed-off-by: Evgenii Shatokhin <eshatokhin@odin.com>
If a static variable is a pointer, it has rela section.
Example:
static int *p = &a;
changed to:
static int *p = &b;
so its rela section has changed.
Then this change of data should be found and report error.
But if we don't correlate its rela section, we won't
find this change.
Signed-off-by: Zhou ChengMing <zhouchengming1@outlook.com>
