On 4/8/19 9:32 AM, Pawel Wieczorkiewicz wrote:
Up to now the livepatch-build ignores newly created object files.
When patch applies new .c file and augments its Makefile to build it
the resulting object file is not taken into account for final linking
step.
Such newly created object files can be detected by comparing patched/
and original/ directories and copied over to the output directory for
the final linking step.
Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
Reviewed-by: Andra-Irina Paraschiv <[email protected]>
Reviewed-by: Bjoern Doebel <[email protected]>
Reviewed-by: Norbert Manthey <[email protected]>
---
livepatch-build | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/livepatch-build b/livepatch-build
index 796838c..b43730c 100755
--- a/livepatch-build
+++ b/livepatch-build
@@ -146,6 +146,12 @@ function create_patch()
fi
done
+ NEW_FILES=$(comm -23 <(find patched -type f -name '*.o' | cut -f2- -d'/' | sort -u) <(find original -type f -name '*.o' | cut -f2- -d'/' | sort -u))
The paths should be `patched/xen` and `original/xen` so that only
hypervisor changes are processed. It is done this way earlier (see
FILES="$(find xen ...)").
Since process substitution creates a subshell, it might be simpler to do
<(cd patched/xen && find . ...) and then drop the `cut`. Also, the `-u`
argument to sort seems unnecessary.
+ for i in $NEW_FILES; do
+ cp "patched/$i" "output/$i"
+ CHANGED=1
+ done
If the live patch for whatever reason has no "patched" object files and
only "new" object files, then it is not going to do anything useful
since nothing will use the new functions. This should fail to build with
an error. E.g. set NEW=1 above and then later check for CHANGED=0 && NEW=1.
Previously all object files that were linked into the livepatch were
from the output of create-diff-object. This change just includes the
newly built object files directly. I wonder if there are any issues or
subtle differences when doing this? A couple of differences off the top
of my head:
1) The object file will include _everything_ (e.g. potentially unused
functions) while create-diff-object generally only includes the minimum
that is needed.
2) Hooks and ignored functions/sections in the new object file would not
be processed at all.
The was previously a patch on xen-devel which took a different approach
(https://lists.xenproject.org/archives/html/xen-devel/2017-06/msg03532.html).
Perhaps you could look at it and see which approach would be better?
Thanks,
--
Ross Lagerwall
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