[tip: objtool/core] objtool: Do not assume order of parent/child functions

[tip-bot2 for Kristen Carlson Accardi]

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     e000acc145928693833f09152244242a678d3cd5
Gitweb:        https://git.kernel.org/tip/e000acc145928693833f09152244242a678d3cd5
Author:        Kristen Carlson Accardi <kristen@xxxxxxxxxxxxxxx>
AuthorDate:    Wed, 15 Apr 2020 14:04:43 -07:00
Committer:     Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
CommitterDate: Thu, 28 May 2020 11:06:05 -05:00

objtool: Do not assume order of parent/child functions

If a .cold function is examined prior to it's parent, the link
to the parent/child function can be overwritten when the parent
is examined. Only update pfunc and cfunc if they were previously
nil to prevent this from happening.

This fixes an issue seen when compiling with -ffunction-sections.

Signed-off-by: Kristen Carlson Accardi <kristen@xxxxxxxxxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
 tools/objtool/elf.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 8422567..f953d3a 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -434,7 +434,13 @@ static int read_symbols(struct elf *elf)
 			size_t pnamelen;
 			if (sym->type != STT_FUNC)
 				continue;
-			sym->pfunc = sym->cfunc = sym;
+
+			if (sym->pfunc == NULL)
+				sym->pfunc = sym;
+
+			if (sym->cfunc == NULL)
+				sym->cfunc = sym;
+
 			coldstr = strstr(sym->name, ".cold");
 			if (!coldstr)
 				continue;