Merge pull request #879 from jpoimboe/orc

create-diff-object: add ORC section support

kpatch-build/create-diff-object.c

@@ -1998,6 +1998,94 @@ static void kpatch_regenerate_special_section(struct kpatch_elf *kelf,
 	sec->base->data->d_size = dest_offset;
 }
 
+#define ORC_IP_PTR_SIZE 4
+
+/*
+ * This function is similar to kpatch_regenerate_special_section(), but
+ * customized for the ORC-related sections.  ORC is more special than the other
+ * special sections because each ORC entry is split into .orc_unwind (struct
+ * orc_entry) and .orc_unwind_ip.
+ */
+static void kpatch_regenerate_orc_sections(struct kpatch_elf *kelf)
+{
+	struct rela *rela, *safe;
+	char *src, *dest, *str;
+	unsigned int src_idx = 0, dest_idx = 0, orc_entry_size;
+	struct section *orc_sec, *ip_sec;
+
+
+	str = getenv("ORC_STRUCT_SIZE");
+	if (!str)
+		return;
+	orc_entry_size = atoi(str);
+
+	LIST_HEAD(newrelas);
+
+	orc_sec = find_section_by_name(&kelf->sections, ".orc_unwind");
+	ip_sec  = find_section_by_name(&kelf->sections, ".orc_unwind_ip");
+
+	if (!orc_sec || !ip_sec)
+		return;
+
+	if (orc_sec->sh.sh_size % orc_entry_size != 0)
+		ERROR("bad .orc_unwind size");
+
+	if (ip_sec->sh.sh_size !=
+	    (orc_sec->sh.sh_size / orc_entry_size) * ORC_IP_PTR_SIZE)
+		ERROR(".orc_unwind/.orc_unwind_ip size mismatch");
+
+	src = orc_sec->data->d_buf;
+	dest = malloc(orc_sec->sh.sh_size);
+	if (!dest)
+		ERROR("malloc");
+
+	list_for_each_entry_safe(rela, safe, &ip_sec->rela->relas, list) {
+
+		if (rela->sym->type != STT_FUNC || !rela->sym->sec->include)
+			goto next;
+
+		/* copy orc entry */
+		memcpy(dest + (dest_idx * orc_entry_size),
+		       src + (src_idx * orc_entry_size),
+		       orc_entry_size);
+
+		/* move ip rela */
+		list_del(&rela->list);
+		list_add_tail(&rela->list, &newrelas);
+		rela->offset = dest_idx * ORC_IP_PTR_SIZE;
+		rela->sym->include = 1;
+
+		dest_idx++;
+next:
+		src_idx++;
+	}
+
+	if (!dest_idx) {
+		/* no changed or global functions referenced */
+		orc_sec->status = ip_sec->status = ip_sec->rela->status = SAME;
+		orc_sec->include = ip_sec->include = ip_sec->rela->include = 0;
+		free(dest);
+		return;
+	}
+
+	/* overwrite with new relas list */
+	list_replace(&newrelas, &ip_sec->rela->relas);
+
+	/* include the sections */
+	orc_sec->include = ip_sec->include = ip_sec->rela->include = 1;
+
+	/*
+	 * Update data buf/size.
+	 *
+	 * The ip section can keep its old (zeroed data), though its size has
+	 * possibly decreased.  The ip rela section's data buf and size will be
+	 * regenerated in kpatch_rebuild_rela_section_data().
+	 */
+	orc_sec->data->d_buf = dest;
+	orc_sec->data->d_size = dest_idx * orc_entry_size;
+	ip_sec->data->d_size = dest_idx * ORC_IP_PTR_SIZE;
+}
+
 static void kpatch_check_relocations(struct kpatch_elf *kelf)
 {
 	struct rela *rela;
@@ -2278,6 +2366,8 @@ static void kpatch_process_special_sections(struct kpatch_elf *kelf)
 			sec->rela->include = 0;
 		}
 	}
+
+	kpatch_regenerate_orc_sections(kelf);
 }
 
 static struct sym_compare_type *kpatch_elf_locals(struct kpatch_elf *kelf)

kpatch-build/kpatch-build

@@ -260,30 +260,35 @@ find_special_section_data() {
 	fi
 
 	[[ "$CONFIG_PARAVIRT" -eq 0 ]] && AWK_OPTIONS="-vskip_p=1"
+	[[ "$CONFIG_UNWINDER_ORC" -eq 0 ]] && AWK_OPTIONS="$AWK_OPTIONS -vskip_o=1"
+
 	SPECIAL_VARS="$(readelf -wi "$VMLINUX" |
-		gawk --non-decimal-data $AWK_OPTIONS '
-		BEGIN { a = b = p = e = 0 }
+		gawk --non-decimal-data "$AWK_OPTIONS" '
+		BEGIN { a = b = p = e = o = 0 }
 
 		# Set state if name matches
 		a == 0 && /DW_AT_name.* alt_instr[[:space:]]*$/ {a = 1; next}
 		b == 0 && /DW_AT_name.* bug_entry[[:space:]]*$/ {b = 1; next}
 		p == 0 && /DW_AT_name.* paravirt_patch_site[[:space:]]*$/ {p = 1; next}
 		e == 0 && /DW_AT_name.* exception_table_entry[[:space:]]*$/ {e = 1; next}
+		o == 0 && /DW_AT_name.* orc_entry[[:space:]]*$/ {o = 1; next}
 
 		# Reset state unless this abbrev describes the struct size
 		a == 1 && !/DW_AT_byte_size/ { a = 0; next }
 		b == 1 && !/DW_AT_byte_size/ { b = 0; next }
 		p == 1 && !/DW_AT_byte_size/ { p = 0; next }
 		e == 1 && !/DW_AT_byte_size/ { e = 0; next }
+		o == 1 && !/DW_AT_byte_size/ { o = 0; next }
 
 		# Now that we know the size, stop parsing for it
 		a == 1 {printf("export ALT_STRUCT_SIZE=%d\n", $4); a = 2}
 		b == 1 {printf("export BUG_STRUCT_SIZE=%d\n", $4); b = 2}
 		p == 1 {printf("export PARA_STRUCT_SIZE=%d\n", $4); p = 2}
 		e == 1 {printf("export EX_STRUCT_SIZE=%d\n", $4); e = 2}
+		o == 1 {printf("export ORC_STRUCT_SIZE=%d\n", $4); o = 2}
 
 		# Bail out once we have everything
-		a == 2 && b == 2 && (p == 2 || skip_p) && e == 2 {exit}')"
+		a == 2 && b == 2 && (p == 2 || skip_p) && e == 2 && (o == 2 || skip_o) {exit}')"
 
 	[[ -n "$SPECIAL_VARS" ]] && eval "$SPECIAL_VARS"
 
@@ -291,6 +296,7 @@ find_special_section_data() {
 	[[ -z "$BUG_STRUCT_SIZE" ]] && die "can't find special struct bug_entry size"
 	[[ -z "$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"
+	[[ -z "$ORC_STRUCT_SIZE" && "$CONFIG_UNWINDER_ORC" -ne 0 ]] && die "can't find special struct orc_entry size"
 
 	return
 }
@@ -667,12 +673,17 @@ else
 	KBUILD_EXTRA_SYMBOLS="$SYMVERSFILE"
 fi
 
-# optional kernel configs: CONFIG_PARAVIRT
+# optional kernel configs:
 if grep -q "CONFIG_PARAVIRT=y" "$CONFIGFILE"; then
 	CONFIG_PARAVIRT=1
 else
 	CONFIG_PARAVIRT=0
 fi
+if grep -q "CONFIG_UNWINDER_ORC=y" "$CONFIGFILE"; then
+	CONFIG_UNWINDER_ORC=1
+else
+	CONFIG_UNWINDER_ORC=0
+fi
 
 # unsupported kernel option checking: CONFIG_DEBUG_INFO_SPLIT
 grep -q "CONFIG_DEBUG_INFO_SPLIT=y" "$CONFIGFILE" && die "kernel option 'CONFIG_DEBUG_INFO_SPLIT' not supported"