kpatch-build: handle paravirt absence in Linux v6.8+ #1392
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kpatch-build/kpatch-build
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| @@ -438,7 +438,7 @@ find_special_section_data() { | |||
| [[ ${check[i]} && -z "$PRINTK_INDEX_STRUCT_SIZE" ]] && die "can't find special struct pi_entry size" | |||
| [[ ${check[j]} && -z "$JUMP_STRUCT_SIZE" ]] && die "can't find special struct jump_entry size" | |||
| [[ ${check[o]} && -z "$ORC_STRUCT_SIZE" ]] && die "can't find special struct orc_entry size" | |||
| [[ ${check[p]} && -z "$PARA_STRUCT_SIZE" ]] && die "can't find special struct paravirt_patch_site size" | |||
| [[ ${check[p]} && -z "$PARA_STRUCT_SIZE" ]] && ! kernel_version_gte 6.8.0 && die "can't find special struct paravirt_patch_site size" | |||
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I think this second kernel_version_gte check is redundant as ${check[p]} should only be set if it's >= 6.8.0, right?
kpatch-build/create-diff-object.c
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| if (!size) { | ||
| if (uname(&name) < 0) { |
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Unfortunately create-diff-object can't assume that it's building for the currently running kernel. (Think about how it operates when kpatch-build is passed the -r, -s, -v options.)
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kpatch-build/create-diff-object.c
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| if (omit_str) | ||
| omit = atoi(omit_str); | ||
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| if (!size && !omit) { |
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Does this work out if you omitted this "omit" code and left create-diff-object untouched? If I read the code correctly, the group_size callbacks are only executed when their sections are encountered:
kpatch_process_special_sections()
for (special = special_sections; special->name; special++) {
...
sec = find_section_by_name(&kelf->sections, special->name);
if (!sec || !sec->rela)
continue;
kpatch_regenerate_special_section(kelf, lookup, special, sec->rela);
group_size = special->group_size(kelf, src_offset);
So I'd expect create-diff-object would only care about PARA_STRUCT_SIZE when the corresponding .parainstructions section is present. (Which I believe torvalds/linux@f7af6977 removes.)
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You are correct, my bad do not need to even pass omit
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Upstream kernel commit f7af6977621a ("x86/paravirt: Remove no longer
needed paravirt patching code") v6.8+ removed the .parainstructions
section and its paravirt_patch_site struct. Therefore this checks the
kernel version and does not export the struct size if the kernel
version is >= v6.8.0, avoiding the code path for it in
create-diff-object.c entirely.
Fixes: dynup#1380
Signed-off-by: Ryan Sullivan <[email protected]>
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Adds linux kernel version checks to all functions pertaining to struct paravirt_patch_site as it is removed in Linux v6.8+
Fixes: #1380