kpatch-build: ppc64le - Add special section support

Add support for ppc64le specific special sections:

- __ftr_fixup
- __mmu_ftr_fixup
- __fw_ftr_fixup
- __lwsync_fixup

This patch also add #ifdef guards for architecture specific
special sections.

Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>

kpatch-build/create-diff-object.c

@@ -1454,21 +1454,6 @@ static int bug_table_group_size(struct kpatch_elf *kelf, int offset)
 	return size;
 }
 
-static int parainstructions_group_size(struct kpatch_elf *kelf, int offset)
-{
-	static int size = 0;
-	char *str;
-
-	if (!size) {
-		str = getenv("PARA_STRUCT_SIZE");
-		if (!str)
-			ERROR("PARA_STRUCT_SIZE not set");
-		size = atoi(str);
-	}
-
-	return size;
-}
-
 static int ex_table_group_size(struct kpatch_elf *kelf, int offset)
 {
 	static int size = 0;
@@ -1484,6 +1469,22 @@ static int ex_table_group_size(struct kpatch_elf *kelf, int offset)
 	return size;
 }
 
+#ifdef __x86_64__
+static int parainstructions_group_size(struct kpatch_elf *kelf, int offset)
+{
+	static int size = 0;
+	char *str;
+
+	if (!size) {
+		str = getenv("PARA_STRUCT_SIZE");
+		if (!str)
+			ERROR("PARA_STRUCT_SIZE not set");
+		size = atoi(str);
+	}
+
+	return size;
+}
+
 static int altinstructions_group_size(struct kpatch_elf *kelf, int offset)
 {
 	static int size = 0;
@@ -1503,6 +1504,28 @@ static int smp_locks_group_size(struct kpatch_elf *kelf, int offset)
 {
 	return 4;
 }
+#endif
+#ifdef __powerpc__
+static int fixup_entry_group_size(struct kpatch_elf *kelf, int offset)
+{
+	static int size = 0;
+	char *str;
+
+	if (!size) {
+		str = getenv("FIXUP_STRUCT_SIZE");
+		if (!str)
+			ERROR("FIXUP_STRUCT_SIZE not set");
+		size = atoi(str);
+	}
+
+	return size;
+}
+
+static int fixup_lwsync_group_size(struct kpatch_elf *kelf, int offset)
+{
+	return 4;
+}
+#endif
 
 /*
  * The rela groups in the .fixup section vary in size.  The beginning of each
@@ -1557,6 +1580,7 @@ static struct special_section special_sections[] = {
 		.name		= "__bug_table",
 		.group_size	= bug_table_group_size,
 	},
+#ifdef __x86_64__
 	{
 		.name		= ".smp_locks",
 		.group_size	= smp_locks_group_size,
@@ -1565,6 +1589,7 @@ static struct special_section special_sections[] = {
 		.name		= ".parainstructions",
 		.group_size	= parainstructions_group_size,
 	},
+#endif
 	{
 		.name		= ".fixup",
 		.group_size	= fixup_group_size,
@@ -1573,10 +1598,30 @@ static struct special_section special_sections[] = {
 		.name		= "__ex_table", /* must come after .fixup */
 		.group_size	= ex_table_group_size,
 	},
+#ifdef __x86_64__
 	{
 		.name		= ".altinstructions",
 		.group_size	= altinstructions_group_size,
 	},
+#endif
+#ifdef __powerpc__
+	{
+		.name		= "__ftr_fixup",
+		.group_size	= fixup_entry_group_size,
+	},
+	{
+		.name		= "__mmu_ftr_fixup",
+		.group_size	= fixup_entry_group_size,
+	},
+	{
+		.name		= "__fw_ftr_fixup",
+		.group_size	= fixup_entry_group_size,
+	},
+	{
+		.name		= "__lwsync_fixup",
+		.group_size	= fixup_lwsync_group_size,
+	},
+#endif
 	{},
 };
 

kpatch-build/kpatch-build

@@ -180,8 +180,41 @@ gcc_version_check() {
 	return
 }
 
+find_special_section_data_ppc64le() {
+	SPECIAL_VARS=$(readelf -wi "$VMLINUX" |
+		       gawk --non-decimal-data '
+		       BEGIN { f = b = e = 0 }
+
+		       # Set state if name matches
+		       f == 0 && /DW_AT_name.* fixup_entry[[:space:]]*$/ {f = 1; next}
+		       b == 0 && /DW_AT_name.* bug_entry[[:space:]]*$/ {b = 1; next}
+		       e == 0 && /DW_AT_name.* exception_table_entry[[:space:]]*$/ {e = 1; next}
+
+		       # Reset state unless this abbrev describes the struct size
+		       f == 1 && !/DW_AT_byte_size/ { f = 0; next }
+		       b == 1 && !/DW_AT_byte_size/ { b = 0; next }
+		       e == 1 && !/DW_AT_byte_size/ { e = 0; next }
+
+		       # Now that we know the size, stop parsing for it
+		       f == 1 {printf("export FIXUP_STRUCT_SIZE=%d\n", $4); a = 2}
+		       b == 1 {printf("export BUG_STRUCT_SIZE=%d\n", $4); b = 2}
+		       e == 1 {printf("export EX_STRUCT_SIZE=%d\n", $4); e = 2}
+
+		       # Bail out once we have everything
+		       f == 2 && b == 2 && e == 2 {exit}')
+
+	[[ -n $SPECIAL_VARS ]] && eval "$SPECIAL_VARS"
+
+	[[ -z $FIXUP_STRUCT_SIZE ]] && die "can't find special struct fixup_entry size"
+	[[ -z $BUG_STRUCT_SIZE ]] && die "can't find special struct bug_entry size"
+	[[ -z $EX_STRUCT_SIZE ]]  && die "can't find special struct exception_table_entry size"
+
+	return
+}
+
 find_special_section_data() {
 	if [[ $ARCH = "ppc64le" ]]; then
+		find_special_section_data_ppc64le
 		return
 	fi
 
@@ -218,6 +251,7 @@ find_special_section_data() {
 	[[ -z $EX_STRUCT_SIZE ]]  && die "can't find special struct paravirt_patch_site size"
 	[[ -z $PARA_STRUCT_SIZE && $CONFIG_PARAVIRT -ne 0 ]] && die "can't find special struct paravirt_patch_site size"
 
+	return
 }
 
 find_parent_obj() {