Re: [PATCH v12 00/21] Compile-time stack metadata validation

[Chris J Arges <chris.j.arges@canonical.com>]

I got the following compiler error when building v12 of this patchset:

  DESCEND  stacktool
  CC       stacktool.o
  CC       elf.o
  CC       special.o
  CC       arch/x86/decode.o
  LD       arch/x86/stacktool-in.o
  LD       stacktool-in.o
Warning: stacktool: x86 instruction decoder differs from kernel
  LINK     stacktool
stacktool-in.o: In function `elf_close':
(.text+0xe7c): undefined reference to `elf_end'
stacktool-in.o: In function `elf_open':
(.text+0xec7): undefined reference to `elf_version'
stacktool-in.o: In function `elf_open':
(.text+0xf29): undefined reference to `elf_begin'
stacktool-in.o: In function `elf_open':
(.text+0xf42): undefined reference to `gelf_getehdr'
stacktool-in.o: In function `elf_open':
(.text+0xf59): undefined reference to `elf_getshdrnum'
stacktool-in.o: In function `elf_open':
(.text+0xf6f): undefined reference to `elf_getshdrstrndx'
stacktool-in.o: In function `elf_open':
(.text+0xfc9): undefined reference to `elf_getscn'
stacktool-in.o: In function `elf_open':
(.text+0xfdd): undefined reference to `elf_ndxscn'
stacktool-in.o: In function `elf_open':
(.text+0xff2): undefined reference to `gelf_getshdr'
stacktool-in.o: In function `elf_open':
(.text+0x100e): undefined reference to `elf_strptr'
stacktool-in.o: In function `elf_open':
(.text+0x1029): undefined reference to `elf_getdata'
stacktool-in.o: In function `elf_open':
(.text+0x1101): undefined reference to `elf_nextscn'
stacktool-in.o: In function `elf_open':
(.text+0x119e): undefined reference to `gelf_getsym'
stacktool-in.o: In function `elf_open':
(.text+0x11b8): undefined reference to `elf_strptr'
stacktool-in.o: In function `elf_open':
(.text+0x13d4): undefined reference to `gelf_getrela'
collect2: error: ld returned 1 exit status
Makefile:33: recipe for target 'stacktool' failed
make[2]: *** [stacktool] Error 1
Makefile:53: recipe for target 'stacktool' failed
make[1]: *** [stacktool] Error 2
Makefile:1502: recipe for target 'tools/stacktool' failed
make: *** [tools/stacktool] Error 2

The patch below addresses this issue for me.

--

>From 9ec5827aa726300394c0155657820f2595008116 Mon Sep 17 00:00:00 2001
From: Chris J Arges <chris.j.arges@canonical.com>
Date: Tue, 15 Sep 2015 16:45:27 +0000
Subject: [PATCH] x86/stacktool: Fix LDFLAGS order in Makefile

When building tools/stacktool I get a compiler error which causes libelf to not
properly link. This patch adjusts the LDFLAG after the object file, which
allows gcc to properly link.

Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
---
 tools/stacktool/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/stacktool/Makefile b/tools/stacktool/Makefile
index 87a3ee0..9f5d2f9 100644
--- a/tools/stacktool/Makefile
+++ b/tools/stacktool/Makefile
@@ -39,7 +39,7 @@ $(STACKTOOL): $(STACKTOOL_IN)
 	diff -I'^#include' arch/x86/insn/inat.h ../../arch/x86/include/asm/inat.h >/dev/null && \
 	diff -I'^#include' arch/x86/insn/inat_types.h ../../arch/x86/include/asm/inat_types.h >/dev/null) \
 	|| echo "Warning: stacktool: x86 instruction decoder differs from kernel" >&2 )) || true
-	$(QUIET_LINK)$(CC) $(LDFLAGS) $(STACKTOOL_IN) -o $@
+	$(QUIET_LINK)$(CC) $(STACKTOOL_IN) $(LDFLAGS) -o $@
 
 clean:
 	$(call QUIET_CLEAN, stacktool) $(RM) $(STACKTOOL)
-- 
2.5.0