kpatch/0011-support-c-plus-kernel-module.patch

From d170861502e78c396f0283f66f444a496efd11de Mon Sep 17 00:00:00 2001
From: Zhipeng Xie <xiezhipeng1@huawei.com>
Date: Wed, 26 Feb 2020 07:36:59 -0500
Subject: [PATCH 11/23] support c plus kernel module

support GNU_UNIQUE type symbols.
support .group section corelation.
ignore compile warning for third party modules.

Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com>
---
 kpatch-build/create-diff-object.c | 60 +++++++++++++++++++++----------
 kpatch-build/kpatch-build         |  2 +-
 kpatch-build/kpatch-elf.c         |  8 ++++-
 kpatch-build/kpatch-gcc           |  3 +-
 kpatch-build/lookup.c             |  5 ++-
 5 files changed, 55 insertions(+), 23 deletions(-)

diff --git a/kpatch-build/create-diff-object.c b/kpatch-build/create-diff-object.c
index f37d404..d139f45 100644
--- a/kpatch-build/create-diff-object.c
+++ b/kpatch-build/create-diff-object.c
@@ -460,7 +460,7 @@ static void kpatch_compare_correlated_nonrela_section(struct section *sec)
 {
 	struct section *sec1 = sec, *sec2 = sec->twin;
 
-	if (sec1->sh.sh_type != SHT_NOBITS &&
+	if (sec1->sh.sh_type != SHT_NOBITS && sec1->sh.sh_type != SHT_GROUP &&
 	    memcmp(sec1->data->d_buf, sec2->data->d_buf, sec1->data->d_size))
 		sec->status = CHANGED;
 	else
@@ -476,7 +476,7 @@ static void kpatch_compare_correlated_section(struct section *sec)
 	    sec1->sh.sh_flags != sec2->sh.sh_flags ||
 	    sec1->sh.sh_entsize != sec2->sh.sh_entsize ||
 	    (sec1->sh.sh_addralign != sec2->sh.sh_addralign &&
-	     !is_text_section(sec1)))
+	     !is_text_section(sec1) && strcmp(sec1->name, ".rodata")))
 		DIFF_FATAL("%s section header details differ from %s", sec1->name, sec2->name);
 
 	/* Short circuit for mcount sections, we rebuild regardless */
@@ -913,6 +913,34 @@ static void kpatch_correlate_section(struct section *sec1, struct section *sec2)
 		kpatch_correlate_symbol(sec1->sym, sec2->sym);
 }
 
+static int kpatch_correlate_group_section(struct list_head *seclist1,
+		struct list_head *seclist2, struct section *sec1, struct section *sec2)
+{
+	unsigned int *data1, *end1, *data2;
+	struct section *isec1, *isec2;
+
+	if (sec1->data->d_size != sec2->data->d_size)
+		return 1;
+	data1 = sec1->data->d_buf;
+	data2 = sec2->data->d_buf;
+	end1 = sec1->data->d_buf + sec1->data->d_size;
+	data1++;
+	data2++;
+	while (data1 < end1) {
+		isec1 = find_section_by_index(seclist1, *data1);
+		if (!isec1)
+			ERROR("group section not found");
+		isec2 = find_section_by_index(seclist2, *data2);
+		if (!isec2)
+			ERROR("group section not found");
+		if (strcmp(isec1->name, isec2->name))
+			return 1;
+		data1++;
+		data2++;
+	}
+	return 0;
+}
+
 static void kpatch_correlate_sections(struct list_head *seclist1, struct list_head *seclist2)
 {
 	struct section *sec1, *sec2;
@@ -931,14 +959,19 @@ static void kpatch_correlate_sections(struct list_head *seclist1, struct list_he
 				continue;
 
 			/*
-			 * Group sections must match exactly to be correlated.
-			 * Changed group sections are currently not supported.
+			 * Group section的格式为：
+			 * flag
+			 * section index
+			 * section index
+			 * ...
+			 *
+			 * 当C++代码发生修改时，section index可能会发生变化
+			 * 这时候我们就比对一下section index所对应的section的
+			 * name，如果相同，我们就认为这两个group是SAME
 			 */
+
 			if (sec1->sh.sh_type == SHT_GROUP) {
-				if (sec1->data->d_size != sec2->data->d_size)
-					continue;
-				if (memcmp(sec1->data->d_buf, sec2->data->d_buf,
-				           sec1->data->d_size))
+				if (kpatch_correlate_group_section(seclist1, seclist2, sec1, sec2))
 					continue;
 			}
 
@@ -1521,17 +1554,6 @@ static void kpatch_verify_patchability(struct kpatch_elf *kelf)
 			errs++;
 		}
 
-		if (sec->status != SAME && sec->grouped) {
-			log_normal("changed section %s is part of a section group\n",
-				   sec->name);
-			errs++;
-		}
-
-		if (sec->sh.sh_type == SHT_GROUP && sec->status == NEW) {
-			log_normal("new/changed group sections are not supported\n");
-			errs++;
-		}
-
 		/*
 		 * ensure we aren't including .data.* or .bss.*
 		 * (.data.unlikely and .data.once is ok b/c it only has __warned vars)
diff --git a/kpatch-build/kpatch-build b/kpatch-build/kpatch-build
index 4e38412..4896136 100755
--- a/kpatch-build/kpatch-build
+++ b/kpatch-build/kpatch-build
@@ -1157,7 +1157,7 @@ fi
 # column containing lines unique to first file.
 UNDEFINED=$(comm -23 <(sort -u "${TEMPDIR}"/undefined_references) \
 	<(sort -u "${TEMPDIR}"/new_symbols) | tr '\n' ' ')
-[[ -n "$UNDEFINED" ]] && die "Undefined symbols: $UNDEFINED"
+[[ -z "$USERMODBUILDDIR" ]] && [[ -n "$UNDEFINED" ]] && die "Undefined symbols: $UNDEFINED"
 
 cp -f "$TEMPDIR/patch/$MODNAME.ko" "$BASE" || die
 
diff --git a/kpatch-build/kpatch-elf.c b/kpatch-build/kpatch-elf.c
index c6af59e..f76a9eb 100644
--- a/kpatch-build/kpatch-elf.c
+++ b/kpatch-build/kpatch-elf.c
@@ -710,8 +710,14 @@ void kpatch_reindex_elements(struct kpatch_elf *kelf)
 	unsigned int index;
 
 	index = 1; /* elf write function handles NULL section 0 */
-	list_for_each_entry(sec, &kelf->sections, list)
+	list_for_each_entry(sec, &kelf->sections, list) {
 		sec->index = index++;
+		/*
+		 * since we exclude .group section, we clear SHF_GROUP
+		 * for every section in case of link error.
+		 */
+		sec->sh.sh_flags &= (~SHF_GROUP);
+	}
 
 	index = 0;
 	list_for_each_entry(sym, &kelf->symbols, list) {
diff --git a/kpatch-build/kpatch-gcc b/kpatch-build/kpatch-gcc
index 35d7c1c..6ad6ebc 100755
--- a/kpatch-build/kpatch-gcc
+++ b/kpatch-build/kpatch-gcc
@@ -13,7 +13,8 @@ fi
 
 declare -a args=("$@")
 
-if [[ "$TOOLCHAINCMD" =~ "${ARCH_COMPILE}gcc" ]] ; then
+if [[ "$TOOLCHAINCMD" =~ "${ARCH_COMPILE}gcc" ||
+	"$TOOLCHAINCMD" =~ "${ARCH_COMPILE}g++" ]] ; then
 	while [ "$#" -gt 0 ]; do
 		if [ "$1" = "-o" ]; then
 			obj="$2"
diff --git a/kpatch-build/lookup.c b/kpatch-build/lookup.c
index 8387e8b..4e2fcb9 100644
--- a/kpatch-build/lookup.c
+++ b/kpatch-build/lookup.c
@@ -255,6 +255,8 @@ static void symtab_read(struct lookup_table *table, char *path)
 			table->obj_syms[i].bind = STB_GLOBAL;
 		} else if (!strcmp(bind, "WEAK")) {
 			table->obj_syms[i].bind = STB_WEAK;
+		} else if (!strcmp(bind, "UNIQUE")) {
+			table->obj_syms[i].bind = STB_GNU_UNIQUE;
 		} else {
 			ERROR("unknown symbol bind %s", bind);
 		}
@@ -431,7 +433,8 @@ int lookup_global_symbol(struct lookup_table *table, char *name,
 
 	memset(result, 0, sizeof(*result));
 	for_each_obj_symbol(i, sym, table) {
-		if ((sym->bind == STB_GLOBAL || sym->bind == STB_WEAK) &&
+		if ((sym->bind == STB_GLOBAL || sym->bind == STB_WEAK
+			|| sym->bind == STB_GNU_UNIQUE) &&
 		    !strcmp(sym->name, name)) {
 			result->value = sym->value;
 			result->size = sym->size;
-- 
2.18.1