objtool: Validate disassembler headers in libopcodes probegrafted

commit 3f2de814c059 ("objtool: Fix libopcodes linking with static libraries")
tested for libopcodes availability by linking a test snippet with a forward
declaration of disassemble_init_for_target().

However, testing symbol linkage with an extern declaration only verifies
the presence of the library (.so/.a) and bypasses checking for development
headers (binutils-dev). On systems where libopcodes is present without
development headers installed, the probe succeeds, enabling BUILD_DISAS.
Subsequent compilation of objtool then fails:

  fatal error: 'bfd.h' file not found
    113 | #include <bfd.h>

Additionally, the probe invokes $(HOSTCC) without $(HOSTCFLAGS), ignoring
any sysroot or include flags specified for the host compiler.

Fix this by including <bfd.h> and <dis-asm.h> directly in the test snippet,
passing $(HOSTCFLAGS) so host compiler options are respected, and defining
PACKAGE="objtool" to satisfy the configuration check in <bfd.h>.

Fixes: 3f2de814c059 ("objtool: Fix libopcodes linking with static libraries")
Fixes: 436326bc525d ("objtool: fix build failure due to missing libopcodes check")
Reported-by: Alice Ryhl <aliceryhl@google.com>
Assisted-by: Antigravity:Gemini-Next
Signed-off-by: Ulises Mendez Martinez <umendez@google.com>
Link: https://patch.msgid.link/20260904150710.2997558-1-umendez@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

1 files changed, 45 insertions, 0 deletions

diff --git a/scripts/Makefile.userprogs b/scripts/Makefile.userprogs
new file mode 100644
index 000000000..f3a7e1ef3
--- /dev/null
+++ b/scripts/Makefile.userprogs
@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Build userspace programs for the target system
+#
+
+# Executables compiled from a single .c file
+user-csingle	:= $(foreach m, $(userprogs), $(if $($(m)-objs),,$(m)))
+
+# Executables linked based on several .o files
+user-cmulti	:= $(foreach m, $(userprogs), $(if $($(m)-objs),$(m)))
+
+# Objects compiled from .c files
+user-cobjs	:= $(sort $(foreach m, $(userprogs), $($(m)-objs)))
+
+user-csingle	:= $(addprefix $(obj)/, $(user-csingle))
+user-cmulti	:= $(addprefix $(obj)/, $(user-cmulti))
+user-cobjs	:= $(addprefix $(obj)/, $(user-cobjs))
+
+user_ccflags	= -Wp,-MMD,$(depfile) $(KBUILD_USERCFLAGS) $(userccflags) \
+			$($(target-stem)-userccflags)
+user_ldflags	= $(KBUILD_USERLDFLAGS) $(userldflags) $($(target-stem)-userldflags)
+user_ldlibs	= $(userldlibs) $($(target-stem)-userldlibs)
+
+# Create an executable from a single .c file
+quiet_cmd_user_cc_c = CC [U]  $@
+      cmd_user_cc_c = $(CC) $(user_ccflags) $(user_ldflags) -o $@ $< \
+		      $(user_ldlibs)
+$(user-csingle): $(obj)/%: $(src)/%.c FORCE
+	$(call if_changed_dep,user_cc_c)
+
+# Link an executable based on list of .o files
+quiet_cmd_user_ld = LD [U]  $@
+      cmd_user_ld = $(CC) $(user_ldflags) -o $@ \
+		    $(addprefix $(obj)/, $($(target-stem)-objs)) $(user_ldlibs)
+$(user-cmulti): FORCE
+	$(call if_changed,user_ld)
+$(call multi_depend, $(user-cmulti), , -objs)
+
+# Create .o file from a .c file
+quiet_cmd_user_cc_o_c = CC [U]  $@
+      cmd_user_cc_o_c = $(CC) $(user_ccflags) -c -o $@ $<
+$(user-cobjs): $(obj)/%.o: $(src)/%.c FORCE
+	$(call if_changed_dep,user_cc_o_c)
+
+targets += $(user-csingle) $(user-cmulti) $(user-cobjs)