From e48825dd0ec228eba465a73bc7d82c301f5e954c Mon Sep 17 00:00:00 2001 From: Zhipeng Xie Date: Fri, 23 Jul 2021 00:08:12 -0400 Subject: [PATCH] lookup: Add __UNIQUE_ID_ to maybe_discarded_sym list Signed-off-by: Zhipeng Xie --- ...IQUE_ID_-to-maybe_discarded_sym-list.patch | 62 +++++++++++++++++++ kpatch.spec | 9 ++- 2 files changed, 70 insertions(+), 1 deletion(-) create mode 100644 0028-lookup-Add-__UNIQUE_ID_-to-maybe_discarded_sym-list.patch diff --git a/0028-lookup-Add-__UNIQUE_ID_-to-maybe_discarded_sym-list.patch b/0028-lookup-Add-__UNIQUE_ID_-to-maybe_discarded_sym-list.patch new file mode 100644 index 0000000..f7def25 --- /dev/null +++ b/0028-lookup-Add-__UNIQUE_ID_-to-maybe_discarded_sym-list.patch @@ -0,0 +1,62 @@ +From b381a0cc0b900d042ff6a718ef9795101310d702 Mon Sep 17 00:00:00 2001 +From: Kamalesh Babulal +Date: Wed, 17 Jun 2020 19:51:56 +0530 +Subject: [PATCH] lookup: Add __UNIQUE_ID_ to maybe_discarded_sym list + +Linux kernel tristate config options allows selected feature, either to +be built-in to the kernel or to be built as a kernel module. When built +as a kernel module, it's expected that the module, will be built with +module information such as author, license, description and others. + +For each of the modinfo, a corresponding __UNIQUE_ID_ symbol is +generated. Their lookup succeeds in the case of module but fails when +selected to built-in to the kernel, the reason being that the kernel +discards these __UNIQUE_ID_ symbols during linking. Add __UNIQUE_ID_ +symbols to maybe_discarded_sym list, to avoid failure in case of +table->object is vmlinux. + +i.e.: + # cat .config|grep IOSCHED_BFQ (can be compiled as module too) + CONFIG_IOSCHED_BFQ=y + + # readelf -sW ./block/bfq-iosched.o|grep UNIQUE + 219: 0000000000000000 54 OBJECT LOCAL DEFAULT 267 __UNIQUE_ID_description223 + 220: 0000000000000036 16 OBJECT LOCAL DEFAULT 267 __UNIQUE_ID_license222 + 221: 0000000000000046 19 OBJECT LOCAL DEFAULT 267 __UNIQUE_ID_file221 + 222: 0000000000000059 25 OBJECT LOCAL DEFAULT 267 __UNIQUE_ID_author220 + 223: 0000000000000072 22 OBJECT LOCAL DEFAULT 267 __UNIQUE_ID_alias219 + +the line below before the kpatch error, is a debug printf to find the failing lookup symbol: +Failed lookup for __UNIQUE_ID_description223 +/root/kpatch/kpatch-build/create-diff-object: ERROR: bfq-iosched.o: find_local_syms: 180: couldn't find matching bfq-iosched.c local symbols in ./vmlinux symbol table + +with the patch, it successfully builds with both y/m config options: +... +bfq-iosched.o: changed function: bfq_idle_slice_timer +Patched objects: vmlinux +Building patch module: +livepatch-0001-block-bfq-fix-use-after-free-in-b.ko +SUCCESS + +Signed-off-by: Kamalesh Babulal +--- + kpatch-build/lookup.c | 3 ++- + 1 file changed, 2 insertions(+), 1 deletion(-) + +diff --git a/kpatch-build/lookup.c b/kpatch-build/lookup.c +index 4f8c779..9086c9c 100644 +--- a/kpatch-build/lookup.c ++++ b/kpatch-build/lookup.c +@@ -83,7 +83,8 @@ static int maybe_discarded_sym(const char *name) + if (!strncmp(name, "__exitcall_", 11) || + !strncmp(name, "__brk_reservation_fn_", 21) || + !strncmp(name, "__func_stack_frame_non_standard_", 32) || +- !strncmp(name, "__addressable_", 14)) ++ !strncmp(name, "__addressable_", 14) || ++ !strncmp(name, "__UNIQUE_ID_", 12)) + return 1; + + return 0; +-- +2.27.0 + diff --git a/kpatch.spec b/kpatch.spec index 8b969b7..19542e3 100644 --- a/kpatch.spec +++ b/kpatch.spec @@ -1,7 +1,7 @@ Name: kpatch Epoch: 1 Version: 0.9.1 -Release: 14 +Release: 15 Summary: A Linux dynamic kernel patching infrastructure License: GPLv2 @@ -39,6 +39,7 @@ Patch0024:0024-optimize-for-out-of-tree-module.patch Patch0025:0025-Fix-relocation-not-resolved-when-new-functions-expor.patch Patch0026:0026-support-remove-static-variables-using-KPATCH_IGNORE_.patch Patch0027:0027-create-build-diff-support-for-.cold-functions-with-n.patch +Patch0028:0028-lookup-Add-__UNIQUE_ID_-to-maybe_discarded_sym-list.patch BuildRequires: gcc elfutils-libelf-devel uname-build-checks kernel-devel git Requires: bc make gcc patch bison flex openssl-devel @@ -99,6 +100,12 @@ popd %{_mandir}/man1/*.1.gz %changelog +* Fri Jul 23 2021 Xinpeng Liu -1:0.9.1-15 +- Type:enhancement +- ID:NA +- SUG:NA +- DESC: lookup: Add __UNIQUE_ID_ to maybe_discarded_sym list + * Mon May 31 2021 Xinpeng Liu -1:0.9.1-14 - Type:enhancement - ID:NA