From 8143254f9bdf2f893476d892d4178bc2d9570e1c Mon Sep 17 00:00:00 2001 From: Zhipeng Xie Date: Wed, 30 Dec 2020 21:16:01 -0500 Subject: [PATCH] support remove static variables using KPATCH_IGNORE_STATIC Static variables will be removed due to compiler optimization. And some static variables can be treated as new variables, such as static variables in print limit macros. So add KPATCH_IGNORE_STATIC to tell kpatch to treat the static variables as new variables. Signed-off-by: Zhipeng Xie --- ...tatic-variables-using-KPATCH_IGNORE_.patch | 110 ++++++++++++++++++ kpatch.spec | 9 +- 2 files changed, 118 insertions(+), 1 deletion(-) create mode 100644 0026-support-remove-static-variables-using-KPATCH_IGNORE_.patch diff --git a/0026-support-remove-static-variables-using-KPATCH_IGNORE_.patch b/0026-support-remove-static-variables-using-KPATCH_IGNORE_.patch new file mode 100644 index 0000000..a6b1270 --- /dev/null +++ b/0026-support-remove-static-variables-using-KPATCH_IGNORE_.patch @@ -0,0 +1,110 @@ +From 0e08aa99583573953367d5c1ec21901325c7faee Mon Sep 17 00:00:00 2001 +From: Zhipeng Xie +Date: Wed, 30 Dec 2020 21:13:10 -0500 +Subject: [PATCH] support remove static variables using KPATCH_IGNORE_STATIC + +Static variables will be removed due to compiler optimization. +And some static variables can be treated as new variables, such as +static variables in print limit macros. So add KPATCH_IGNORE_STATIC +to tell kpatch to treat the static variables as new variables. + +Signed-off-by: Zhipeng Xie +--- + kmod/patch/kpatch-macros.h | 3 +++ + kpatch-build/create-diff-object.c | 45 ++++++++++++++++++++++++++++++- + 2 files changed, 47 insertions(+), 1 deletion(-) + +diff --git a/kmod/patch/kpatch-macros.h b/kmod/patch/kpatch-macros.h +index a60a267..9a30d68 100644 +--- a/kmod/patch/kpatch-macros.h ++++ b/kmod/patch/kpatch-macros.h +@@ -5,6 +5,9 @@ + #include + #include + ++#define KPATCH_IGNORE_STATIC(_static) \ ++ char *__UNIQUE_ID(kpatch_ignore_static_) __section(.kpatch.ignore.statics) = _static; ++ + /* + * KPATCH_IGNORE_SECTION macro + * +diff --git a/kpatch-build/create-diff-object.c b/kpatch-build/create-diff-object.c +index a2a9cab..211ea72 100644 +--- a/kpatch-build/create-diff-object.c ++++ b/kpatch-build/create-diff-object.c +@@ -1151,6 +1151,40 @@ static int kpatch_is_normal_static_local(struct symbol *sym) + return 1; + } + ++static int kpatch_mark_ignored_statics(struct kpatch_elf *kelf, struct symbol *sym) ++{ ++ struct section *sec, *strsec; ++ struct rela *rela; ++ char *name; ++ ++ sec = find_section_by_name(&kelf->sections, ".kpatch.ignore.statics"); ++ if (!sec) ++ return 0; ++ ++ list_for_each_entry(rela, &sec->rela->relas, list) { ++ strsec = rela->sym->sec; ++ strsec->status = CHANGED; ++ /* ++ * Include the string section here. This is because the ++ * KPATCH_IGNORE_STATIC() macro is passed a literal string ++ * by the patch author, resulting in a change to the string ++ * section. If we don't include it, then we will potentially ++ * get a "changed section not included" error in ++ * kpatch_verify_patchability() if no other function based change ++ * also changes the string section. We could try to exclude each ++ * literal string added to the section by KPATCH_IGNORE_STATIC() ++ * from the section data comparison, but this is a simpler way. ++ */ ++ strsec->include = 1; ++ strsec->secsym->include = 1; ++ name = strsec->data->d_buf + rela->addend; ++ if (!strncmp(name, sym->name, strlen(name))) ++ return 1; ++ } ++ ++ return 0; ++} ++ + /* + * gcc renames static local variables by appending a period and a number. For + * example, __foo could be renamed to __foo.31452. Unfortunately this number +@@ -1230,6 +1264,11 @@ static void kpatch_correlate_static_local_variables(struct kpatch_elf *base, + if (sym->twin) + continue; + ++ if (kpatch_mark_ignored_statics(patched, sym)) { ++ log_normal("KPATCH_IGNORE_STATIC:ignore static variable %s\n", sym->name); ++ continue; ++ } ++ + bundled = sym == sym->sec->sym; + if (bundled && sym->sec == sec->base) { + /* +@@ -1286,6 +1325,11 @@ static void kpatch_correlate_static_local_variables(struct kpatch_elf *base, + if (!kpatch_is_normal_static_local(sym)) + continue; + ++ if (kpatch_mark_ignored_statics(patched, sym)) { ++ log_normal("KPATCH_IGNORE_STATIC:ignore static variable %s\n", sym->name); ++ continue; ++ } ++ + if (!sym->twin || !sec->twin) + DIFF_FATAL("reference to static local variable %s in %s was removed", + sym->name, +@@ -1329,7 +1373,6 @@ static void kpatch_correlate_static_local_variables(struct kpatch_elf *base, + log_normal("WARNING: unable to correlate static local variable %s used by %s, assuming variable is new\n", + sym->name, + kpatch_section_function_name(sec)); +- return; + } + } + } +-- +2.18.1 + diff --git a/kpatch.spec b/kpatch.spec index c9f1433..6bee6f9 100644 --- a/kpatch.spec +++ b/kpatch.spec @@ -1,7 +1,7 @@ Name: kpatch Epoch: 1 Version: 0.9.1 -Release: 8 +Release: 9 Summary: A Linux dynamic kernel patching infrastructure License: GPLv2 @@ -37,6 +37,7 @@ Patch0022:0022-support-force-enable-disable-for-x86.patch Patch0023:0023-create-diff-object-fix-duplicate-symbols-for-vmlinux.patch 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 BuildRequires: gcc elfutils-libelf-devel uname-build-checks kernel-devel git Requires: bc @@ -96,6 +97,12 @@ popd %{_mandir}/man1/*.1.gz %changelog +* Wed Dec 31 2020 Zhipeng Xie -1:0.9.1-9 +- Type:bugfix +- ID:NA +- SUG:NA +- DESC:support remove static variables using KPATCH_IGNORE_STATIC + * Sun Nov 22 2020 Zhipeng Xie -1:0.9.1-8 - Type:bugfix - ID:NA