[tip:x86/pti] objtool: Warn on stripped section symbol

[tip-bot for Josh Poimboeuf <tipbot@zytor.com>]

Commit-ID:  830c1e3d16b2c1733cd1ec9c8f4d47a398ae31bc
Gitweb:     https://git.kernel.org/tip/830c1e3d16b2c1733cd1ec9c8f4d47a398ae31bc
Author:     Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Mon, 29 Jan 2018 22:00:41 -0600
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 30 Jan 2018 15:09:23 +0100

objtool: Warn on stripped section symbol

With the following fix:

  2a0098d70640 ("objtool: Fix seg fault with gold linker")

... a seg fault was avoided, but the original seg fault condition in
objtool wasn't fixed.  Replace the seg fault with an error message.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/dc4585a70d6b975c99fc51d1957ccdde7bd52f3a.1517284349.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 tools/objtool/orc_gen.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index e61fe70..18384d9 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -98,6 +98,11 @@ static int create_orc_entry(struct section *u_sec, struct section *ip_relasec,
 	struct orc_entry *orc;
 	struct rela *rela;
 
+	if (!insn_sec->sym) {
+		WARN("missing symbol for section %s", insn_sec->name);
+		return -1;
+	}
+
 	/* populate ORC data */
 	orc = (struct orc_entry *)u_sec->data->d_buf + idx;
 	memcpy(orc, o, sizeof(*orc));