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, 77 insertions, 0 deletions

diff --git a/net/Makefile b/net/Makefile
new file mode 100644
index 000000000..5b2dd7f07
--- /dev/null
+++ b/net/Makefile
@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the linux networking.
+#
+# 2 Sep 2000, Christoph Hellwig <hch@infradead.org>
+# Rewritten to use lists instead of if-statements.
+#
+
+obj-y				:= devres.o socket.o core/
+
+obj-$(CONFIG_COMPAT)		+= compat.o
+
+# LLC has to be linked before the files in net/802/
+obj-$(CONFIG_LLC)		+= llc/
+obj-y				+= ethernet/ 802/ sched/ netlink/ bpf/ ethtool/
+obj-$(CONFIG_NETFILTER)		+= netfilter/
+obj-$(CONFIG_INET)		+= ipv4/
+obj-$(CONFIG_TLS)		+= tls/
+obj-$(CONFIG_XFRM)		+= xfrm/
+obj-$(CONFIG_UNIX)		+= unix/
+obj-$(CONFIG_INET_PSP)		+= psp/
+obj-y				+= ipv6/
+obj-$(CONFIG_PACKET)		+= packet/
+obj-$(CONFIG_NET_KEY)		+= key/
+obj-$(CONFIG_BRIDGE)		+= bridge/
+obj-$(CONFIG_NET_DEVLINK)	+= devlink/
+obj-y				+= dsa/
+obj-$(CONFIG_X25)		+= x25/
+obj-$(CONFIG_LAPB)		+= lapb/
+obj-$(CONFIG_CAN)		+= can/
+obj-$(CONFIG_BT)		+= bluetooth/
+obj-$(CONFIG_SUNRPC)		+= sunrpc/
+obj-$(CONFIG_AF_RXRPC)		+= rxrpc/
+obj-$(CONFIG_AF_KCM)		+= kcm/
+obj-$(CONFIG_STREAM_PARSER)	+= strparser/
+obj-$(CONFIG_ATM)		+= atm/
+obj-$(CONFIG_L2TP)		+= l2tp/
+obj-$(CONFIG_PHONET)		+= phonet/
+ifneq ($(CONFIG_VLAN_8021Q),)
+obj-y				+= 8021q/
+endif
+obj-$(CONFIG_IP_SCTP)		+= sctp/
+obj-$(CONFIG_RDS)		+= rds/
+obj-$(CONFIG_WIRELESS)		+= wireless/
+obj-$(CONFIG_MAC80211)		+= mac80211/
+obj-$(CONFIG_TIPC)		+= tipc/
+obj-$(CONFIG_NETLABEL)		+= netlabel/
+obj-$(CONFIG_IUCV)		+= iucv/
+obj-$(CONFIG_SMC)		+= smc/
+obj-$(CONFIG_RFKILL)		+= rfkill/
+obj-$(CONFIG_NET_9P)		+= 9p/
+obj-$(CONFIG_DCB)		+= dcb/
+obj-$(CONFIG_6LOWPAN)		+= 6lowpan/
+obj-$(CONFIG_IEEE802154)	+= ieee802154/
+obj-$(CONFIG_MAC802154)		+= mac802154/
+
+obj-$(CONFIG_SYSCTL)		+= sysctl_net.o
+obj-$(CONFIG_DNS_RESOLVER)	+= dns_resolver/
+obj-$(CONFIG_CEPH_LIB)		+= ceph/
+obj-$(CONFIG_BATMAN_ADV)	+= batman-adv/
+obj-$(CONFIG_NFC)		+= nfc/
+obj-$(CONFIG_PSAMPLE)		+= psample/
+obj-$(CONFIG_NET_IFE)		+= ife/
+obj-$(CONFIG_OPENVSWITCH)	+= openvswitch/
+obj-$(CONFIG_VSOCKETS)	+= vmw_vsock/
+obj-$(CONFIG_MPLS)		+= mpls/
+obj-$(CONFIG_NET_NSH)		+= nsh/
+obj-$(CONFIG_HSR)		+= hsr/
+obj-$(CONFIG_NET_SWITCHDEV)	+= switchdev/
+obj-$(CONFIG_NET_L3_MASTER_DEV)	+= l3mdev/
+obj-$(CONFIG_QRTR)		+= qrtr/
+obj-$(CONFIG_NET_NCSI)		+= ncsi/
+obj-$(CONFIG_XDP_SOCKETS)	+= xdp/
+obj-$(CONFIG_MPTCP)		+= mptcp/
+obj-$(CONFIG_MCTP)		+= mctp/
+obj-$(CONFIG_NET_HANDSHAKE)	+= handshake/
+obj-$(CONFIG_NET_SHAPER)	+= shaper/