From 413d7e988102a6cd085650909c98d54656295de9 Mon Sep 17 00:00:00 2001
From: Zhipeng Xie <xiezhipeng1@huawei.com>
Date: Wed, 26 Feb 2020 07:36:59 -0500
Subject: [PATCH 09/37] support c++ 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 | 48 ++++++++++++++++++++-----------
 kpatch-build/kpatch-cc            |  4 ++-
 kpatch-build/kpatch-elf.c         |  8 +++++-
 kpatch-build/lookup.c             |  5 +++-
 4 files changed, 45 insertions(+), 20 deletions(-)

diff --git a/kpatch-build/create-diff-object.c b/kpatch-build/create-diff-object.c
index 64b63e3..7e415dd 100644
--- a/kpatch-build/create-diff-object.c
+++ b/kpatch-build/create-diff-object.c
@@ -554,7 +554,7 @@ 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
@@ -570,7 +570,7 @@ 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 */
@@ -1006,6 +1006,34 @@ static void kpatch_correlate_section(struct section *sec_orig,
 		kpatch_correlate_symbol(sec_orig->sym, sec_patched->sym);
 }
 
+static int kpatch_correlate_group_section(struct list_head *seclist_orig,
+		struct list_head *seclist_patched, 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(seclist_orig, *data1);
+		if (!isec1)
+			ERROR("group section not found");
+		isec2 = find_section_by_index(seclist_patched, *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 *seclist_orig,
 		struct list_head *seclist_patched)
 {
@@ -1029,10 +1057,7 @@ static void kpatch_correlate_sections(struct list_head *seclist_orig,
 			 * Changed group sections are currently not supported.
 			 */
 			if (sec_orig->sh.sh_type == SHT_GROUP) {
-				if (sec_orig->data->d_size != sec_patched->data->d_size)
-					continue;
-				if (memcmp(sec_orig->data->d_buf, sec_patched->data->d_buf,
-				           sec_orig->data->d_size))
+				if (kpatch_correlate_group_section(seclist_orig, seclist_patched, sec_orig, sec_patched))
 					continue;
 			}
 
@@ -1682,17 +1707,6 @@ 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-cc b/kpatch-build/kpatch-cc
index 991bcad..5e241dd 100755
--- a/kpatch-build/kpatch-cc
+++ b/kpatch-build/kpatch-cc
@@ -13,7 +13,9 @@ fi
 
 declare -a args=("$@")
 
-if [[ "$TOOLCHAINCMD" =~ ^(.*-)?gcc$ || "$TOOLCHAINCMD" =~ ^(.*-)?clang$ ]] ; then
+if [[ "$TOOLCHAINCMD" =~ ^(.*-)?gcc$ ||
+	"$TOOLCHAINCMD" =~ ^(.*-)?g\+\+$ ||
+	"$TOOLCHAINCMD" =~ ^(.*-)?clang$ ]] ; then
 	while [ "$#" -gt 0 ]; do
 		if [ "$1" = "-o" ]; then
 			obj="$2"
diff --git a/kpatch-build/kpatch-elf.c b/kpatch-build/kpatch-elf.c
index 069e102..877deac 100644
--- a/kpatch-build/kpatch-elf.c
+++ b/kpatch-build/kpatch-elf.c
@@ -851,8 +851,14 @@ 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/lookup.c b/kpatch-build/lookup.c
index f2596b1..829250f 100644
--- a/kpatch-build/lookup.c
+++ b/kpatch-build/lookup.c
@@ -306,6 +306,8 @@ 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);
 		}
@@ -530,7 +532,8 @@ static bool 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)) {
 
 			if (result->objname)
-- 
2.33.0