When building the patched version of the kernel, vmlinux has to be
linked with the '--warn-unresolved-symbols' linker flag. Otherwise the
link will fail if the patch uses kpatch-specific symbols like
kpatch_shadow_alloc() and friends.
As of upstream Linux commit b36fad65d61f ("kbuild: Initialize exported
variables"), LDFLAGS_vmlinux= no longer works from the command line,
resulting in '--warn-unresolved-symbols' no longer getting set.
Instead we can use kpatch-gcc to pass the flag to the linker.
Fixes#627.
The user's environment might have TEMPDIR exported. If so, then kpatch-build
dies with a bogus "invalid ancestor" error. If you turn those bogus errors into
warnings, then the script goes on to incorrectly put into the generated .ko file
every single function that was compiled in the *original* kernel build, thereby
producing an immense .ko file with more than 64k sections that the linux kernel
cannot load. This fix makes sure that TEMPDIR is unexported on the build of the
original kernel. Actually, this fix uses a separate KPATCH_GCC_TEMPDIR variable,
so that if the kernel build is interrupted, the cleanup function in the kpatch-kbuild
script will still have TEMPDIR set correctly.
Signed-off-by: Martin Carroll <martin.carroll@alcatel-lucent.com>
vdso files aren't kpatch-compatible, and give errors like the following:
ERROR: invalid ancestor arch/x86/vdso/vdso32-sysenter.so.dbg for arch/x86/vdso/vdso32/sysenter.o
Fixes an error when the following is an argument to gcc:
'-DIPATH_IDSTR="QLogic' kernel.org 'driver"'
gcc: error: kernel.org: No such file or directory
gcc: error: driver": No such file or directory
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.
Right now, we do three build passes: one to build the original tree
(full) build, one to build the patch tree (diff build), then one to
rebuild original objects that where changed by the patch (diff build).
This is going to be a problem when we try to support (near) full tree
rebuilds due to changes in commonly included header files.
This commit changes the build process to intercept calls to gcc by make
using the CROSS_COMPILE environment variable and, during the patched
build phase, copies the original object for any object that is about to
rebuilt due to a change.
This reduces the number of build passes to the minimum possible (two).
Signed-off-by: Seth Jennings <sjenning@redhat.com>
