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objtool: fix build failure due to missing libopcodes check

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Commit 5995330382 ("objtool: Disassemble code with libopcodes instead
of running objdump") added support for using libopcodes for disassembly.
However, the feature detection checks for libbfd availability but then
unconditionally links against libopcodes:

  ifeq ($(feature-libbfd),1)
      OBJTOOL_LDFLAGS += -lopcodes
  endif

This causes build failures in environments where libbfd is installed but
libopcodes is not, since the test-libbfd.c feature test only links
against -lbfd and -ldl, not -lopcodes:

  /usr/bin/ld: cannot find -lopcodes: No such file or directory
  collect2: error: ld returned 1 exit status
  make[4]: *** [Makefile:109: objtool] Error 1

Additionally, the shared feature framework uses $(CC) which is the
cross-compiler in cross-compilation builds. Since objtool is a host tool
that links with $(HOSTCC) against host libraries, the feature detection
can falsely report libopcodes as available when the cross-compiler's
sysroot has it but the host system doesn't.

Fix this by replacing the feature framework check with a direct inline
test that uses $(HOSTCC) to compile and link a test program against
libopcodes, similar to how xxhash availability is detected.

Fixes: 5995330382 ("objtool: Disassemble code with libopcodes instead of running objdump")
Assisted-by: claude-opus-4-5-20251101
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251223120357.2492008-1-sashal@kernel.org
This commit is contained in:
Sasha Levin
2025-12-23 07:03:57 -05:00
committed by Peter Zijlstra
parent 26bea10450
commit 436326bc52
1 changed files with 14 additions and 10 deletions
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24
tools/objtool/Makefile
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@@ -72,23 +72,27 @@ HOST_OVERRIDES := CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)"
#
# To support disassembly, objtool needs libopcodes which is provided
# with libbdf (binutils-dev or binutils-devel package).
# with libbfd (binutils-dev or binutils-devel package).
#
FEATURE_USER = .objtool
FEATURE_TESTS = libbfd disassembler-init-styled
FEATURE_DISPLAY =
include $(srctree)/tools/build/Makefile.feature
# 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; }' | \
$(HOSTCC) -xc - -o /dev/null -lopcodes 2>/dev/null && echo y)
ifeq ($(feature-disassembler-init-styled), 1)
OBJTOOL_CFLAGS += -DDISASM_INIT_STYLED
endif
# Styled disassembler support requires binutils >= 2.39
HAVE_DISASM_STYLED := $(shell echo '$(pound)include <dis-asm.h>' | \
$(HOSTCC) -E -xc - 2>/dev/null | grep -q disassembler_style && echo y)
BUILD_DISAS := n
ifeq ($(feature-libbfd),1)
ifeq ($(HAVE_LIBOPCODES),y)
BUILD_DISAS := y
OBJTOOL_CFLAGS += -DDISAS -DPACKAGE="objtool"
OBJTOOL_CFLAGS += -DDISAS -DPACKAGE='"objtool"'
OBJTOOL_LDFLAGS += -lopcodes
ifeq ($(HAVE_DISASM_STYLED),y)
OBJTOOL_CFLAGS += -DDISASM_INIT_STYLED
endif
endif
export BUILD_DISAS