Commit 3f2de814 authored by Sasha Levin's avatar Sasha Levin Committed by Peter Zijlstra
Browse files

objtool: Fix libopcodes linking with static libraries 



Commit 436326bc ("objtool: fix build failure due to missing libopcodes
check") tests for libopcodes using an empty main(), which passes even when
static libraries lack their dependencies. This causes undefined reference
errors (xmalloc, bfd_get_bits, etc.) when linking against static libopcodes
without its required libbfd and libiberty.

Fix by testing with an actual libopcodes symbol and trying increasingly
complete library combinations until one succeeds.

Fixes: 436326bc ("objtool: fix build failure due to missing libopcodes check")
Reported-by: default avatarRafael J. Wysocki <rafael@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarRafael J. Wysocki (Intel) <rafael@kernel.org>
Link: https://patch.msgid.link/20260121162532.1596238-1-sashal@kernel.org
parent 24d479d2

tools/objtool/Makefile

+17 −4
Original line number Diff line number Diff line
@@ -77,8 +77,21 @@ HOST_OVERRIDES := CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)" 
# We check using HOSTCC directly rather than the shared feature framework

# because objtool is a host tool that links against host libraries.

#

HAVE_LIBOPCODES := $(shell echo 'int main(void) { return 0; }' | \

			$(HOSTCC) -xc - -o /dev/null -lopcodes 2>/dev/null && echo y)

# When using shared libraries, -lopcodes is sufficient as dependencies are

# resolved automatically. With static libraries, we must explicitly link

# against libopcodes' dependencies: libbfd, libiberty, and sometimes libz.

# Try each combination and use the first one that succeeds.

#

LIBOPCODES_LIBS := $(shell \

	for libs in "-lopcodes" \

		    "-lopcodes -lbfd" \

		    "-lopcodes -lbfd -liberty" \

		    "-lopcodes -lbfd -liberty -lz"; do \

		echo 'extern void disassemble_init_for_target(void *);' \

		     'int main(void) { disassemble_init_for_target(0); return 0; }' | \

			$(HOSTCC) -xc - -o /dev/null $$libs 2>/dev/null && \

			echo "$$libs" && break; \

	done)



# Styled disassembler support requires binutils >= 2.39

HAVE_DISASM_STYLED := $(shell echo '$(pound)include <dis-asm.h>' | \
@@ -86,10 +99,10 @@ HAVE_DISASM_STYLED := $(shell echo '$(pound)include <dis-asm.h>' | \ 


BUILD_DISAS := n



ifeq ($(HAVE_LIBOPCODES),y)

ifneq ($(LIBOPCODES_LIBS),)

	BUILD_DISAS := y

	OBJTOOL_CFLAGS += -DDISAS -DPACKAGE='"objtool"'

	OBJTOOL_LDFLAGS += -lopcodes

	OBJTOOL_LDFLAGS += $(LIBOPCODES_LIBS)

ifeq ($(HAVE_DISASM_STYLED),y)

	OBJTOOL_CFLAGS += -DDISASM_INIT_STYLED

endif