2 files changed, 51 insertions, 13 deletions

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 3a31b238f885..f4a25bd1871f 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -164,6 +164,7 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"lbug_with_loc",
 		"fortify_panic",
 		"usercopy_abort",
+		"machine_real_restart",
 	};
 
 	if (func->bind == STB_WEAK)
@@ -543,6 +544,28 @@ static int add_jump_destinations(struct objtool_file *file)
 				  dest_off);
 			return -1;
 		}
+
+		/*
+		 * For GCC 8+, create parent/child links for any cold
+		 * subfunctions.  This is _mostly_ redundant with a similar
+		 * initialization in read_symbols().
+		 *
+		 * If a function has aliases, we want the *first* such function
+		 * in the symbol table to be the subfunction's parent.  In that
+		 * case we overwrite the initialization done in read_symbols().
+		 *
+		 * However this code can't completely replace the
+		 * read_symbols() code because this doesn't detect the case
+		 * where the parent function's only reference to a subfunction
+		 * is through a switch table.
+		 */
+		if (insn->func && insn->jump_dest->func &&
+		    insn->func != insn->jump_dest->func &&
+		    !strstr(insn->func->name, ".cold.") &&
+		    strstr(insn->jump_dest->func->name, ".cold.")) {
+			insn->func->cfunc = insn->jump_dest->func;
+			insn->jump_dest->func->pfunc = insn->func;
+		}
 	}
 
 	return 0;
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 4e60e105583e..0d1acb704f64 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -302,19 +302,34 @@ static int read_symbols(struct elf *elf)
 				continue;
 			sym->pfunc = sym->cfunc = sym;
 			coldstr = strstr(sym->name, ".cold.");
-			if (coldstr) {
-				coldstr[0] = '\0';
-				pfunc = find_symbol_by_name(elf, sym->name);
-				coldstr[0] = '.';
-
-				if (!pfunc) {
-					WARN("%s(): can't find parent function",
-					     sym->name);
-					goto err;
-				}
-
-				sym->pfunc = pfunc;
-				pfunc->cfunc = sym;
+			if (!coldstr)
+				continue;
+
+			coldstr[0] = '\0';
+			pfunc = find_symbol_by_name(elf, sym->name);
+			coldstr[0] = '.';
+
+			if (!pfunc) {
+				WARN("%s(): can't find parent function",
+				     sym->name);
+				goto err;
+			}
+
+			sym->pfunc = pfunc;
+			pfunc->cfunc = sym;
+
+			/*
+			 * Unfortunately, -fnoreorder-functions puts the child
+			 * inside the parent.  Remove the overlap so we can
+			 * have sane assumptions.
+			 *
+			 * Note that pfunc->len now no longer matches
+			 * pfunc->sym.st_size.
+			 */
+			if (sym->sec == pfunc->sec &&
+			    sym->offset >= pfunc->offset &&
+			    sym->offset + sym->len == pfunc->offset + pfunc->len) {
+				pfunc->len -= sym->len;
 			}
 		}
 	}