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>

21 files changed, 117 insertions, 0 deletions

diff --git a/scripts/atomic/fallbacks/acquire b/scripts/atomic/fallbacks/acquire
new file mode 100755
index 000000000..4da0cab36
--- /dev/null
+++ b/scripts/atomic/fallbacks/acquire
@@ -0,0 +1,5 @@
+cat <<EOF
+	${ret} ret = arch_${atomic}_${pfx}${name}${sfx}_relaxed(${args});
+	__atomic_acquire_fence();
+	return ret;
+EOF
diff --git a/scripts/atomic/fallbacks/add_negative b/scripts/atomic/fallbacks/add_negative
new file mode 100755
index 000000000..1d3d4ab3a
--- /dev/null
+++ b/scripts/atomic/fallbacks/add_negative
@@ -0,0 +1,3 @@
+cat <<EOF
+	return raw_${atomic}_add_return${order}(i, v) < 0;
+EOF
diff --git a/scripts/atomic/fallbacks/add_unless b/scripts/atomic/fallbacks/add_unless
new file mode 100755
index 000000000..95ecb2b74
--- /dev/null
+++ b/scripts/atomic/fallbacks/add_unless
@@ -0,0 +1,3 @@
+cat << EOF
+	return raw_${atomic}_fetch_add_unless(v, a, u) != u;
+EOF
diff --git a/scripts/atomic/fallbacks/andnot b/scripts/atomic/fallbacks/andnot
new file mode 100755
index 000000000..66760457e
--- /dev/null
+++ b/scripts/atomic/fallbacks/andnot
@@ -0,0 +1,3 @@
+cat <<EOF
+	${retstmt}raw_${atomic}_${pfx}and${sfx}${order}(~i, v);
+EOF
diff --git a/scripts/atomic/fallbacks/cmpxchg b/scripts/atomic/fallbacks/cmpxchg
new file mode 100644
index 000000000..1c8507f62
--- /dev/null
+++ b/scripts/atomic/fallbacks/cmpxchg
@@ -0,0 +1,3 @@
+cat <<EOF
+	return raw_cmpxchg${order}(&v->counter, old, new);
+EOF
diff --git a/scripts/atomic/fallbacks/dec b/scripts/atomic/fallbacks/dec
new file mode 100755
index 000000000..60d286d40
--- /dev/null
+++ b/scripts/atomic/fallbacks/dec
@@ -0,0 +1,3 @@
+cat <<EOF
+	${retstmt}raw_${atomic}_${pfx}sub${sfx}${order}(1, v);
+EOF
diff --git a/scripts/atomic/fallbacks/dec_and_test b/scripts/atomic/fallbacks/dec_and_test
new file mode 100755
index 000000000..3a0278e0d
--- /dev/null
+++ b/scripts/atomic/fallbacks/dec_and_test
@@ -0,0 +1,3 @@
+cat <<EOF
+	return raw_${atomic}_dec_return(v) == 0;
+EOF
diff --git a/scripts/atomic/fallbacks/dec_if_positive b/scripts/atomic/fallbacks/dec_if_positive
new file mode 100755
index 000000000..f65c11b4b
--- /dev/null
+++ b/scripts/atomic/fallbacks/dec_if_positive
@@ -0,0 +1,11 @@
+cat <<EOF
+	${int} dec, c = raw_${atomic}_read(v);
+
+	do {
+		dec = c - 1;
+		if (unlikely(dec < 0))
+			break;
+	} while (!raw_${atomic}_try_cmpxchg(v, &c, dec));
+
+	return dec;
+EOF
diff --git a/scripts/atomic/fallbacks/dec_unless_positive b/scripts/atomic/fallbacks/dec_unless_positive
new file mode 100755
index 000000000..d025361d7
--- /dev/null
+++ b/scripts/atomic/fallbacks/dec_unless_positive
@@ -0,0 +1,10 @@
+cat <<EOF
+	${int} c = raw_${atomic}_read(v);
+
+	do {
+		if (unlikely(c > 0))
+			return false;
+	} while (!raw_${atomic}_try_cmpxchg(v, &c, c - 1));
+
+	return true;
+EOF
diff --git a/scripts/atomic/fallbacks/fence b/scripts/atomic/fallbacks/fence
new file mode 100755
index 000000000..40d5b3976
--- /dev/null
+++ b/scripts/atomic/fallbacks/fence
@@ -0,0 +1,7 @@
+cat <<EOF
+	${ret} ret;
+	__atomic_pre_full_fence();
+	ret = arch_${atomic}_${pfx}${name}${sfx}_relaxed(${args});
+	__atomic_post_full_fence();
+	return ret;
+EOF
diff --git a/scripts/atomic/fallbacks/fetch_add_unless b/scripts/atomic/fallbacks/fetch_add_unless
new file mode 100755
index 000000000..8db7e9e17
--- /dev/null
+++ b/scripts/atomic/fallbacks/fetch_add_unless
@@ -0,0 +1,10 @@
+cat << EOF
+	${int} c = raw_${atomic}_read(v);
+
+	do {
+		if (unlikely(c == u))
+			break;
+	} while (!raw_${atomic}_try_cmpxchg(v, &c, c + a));
+
+	return c;
+EOF
diff --git a/scripts/atomic/fallbacks/inc b/scripts/atomic/fallbacks/inc
new file mode 100755
index 000000000..56c770f59
--- /dev/null
+++ b/scripts/atomic/fallbacks/inc
@@ -0,0 +1,3 @@
+cat <<EOF
+	${retstmt}raw_${atomic}_${pfx}add${sfx}${order}(1, v);
+EOF
diff --git a/scripts/atomic/fallbacks/inc_and_test b/scripts/atomic/fallbacks/inc_and_test
new file mode 100755
index 000000000..7d16a10f2
--- /dev/null
+++ b/scripts/atomic/fallbacks/inc_and_test
@@ -0,0 +1,3 @@
+cat <<EOF
+	return raw_${atomic}_inc_return(v) == 0;
+EOF
diff --git a/scripts/atomic/fallbacks/inc_not_zero b/scripts/atomic/fallbacks/inc_not_zero
new file mode 100755
index 000000000..1fcef1e55
--- /dev/null
+++ b/scripts/atomic/fallbacks/inc_not_zero
@@ -0,0 +1,3 @@
+cat <<EOF
+	return raw_${atomic}_add_unless(v, 1, 0);
+EOF
diff --git a/scripts/atomic/fallbacks/inc_unless_negative b/scripts/atomic/fallbacks/inc_unless_negative
new file mode 100755
index 000000000..7b4b09868
--- /dev/null
+++ b/scripts/atomic/fallbacks/inc_unless_negative
@@ -0,0 +1,10 @@
+cat <<EOF
+	${int} c = raw_${atomic}_read(v);
+
+	do {
+		if (unlikely(c < 0))
+			return false;
+	} while (!raw_${atomic}_try_cmpxchg(v, &c, c + 1));
+
+	return true;
+EOF
diff --git a/scripts/atomic/fallbacks/read_acquire b/scripts/atomic/fallbacks/read_acquire
new file mode 100755
index 000000000..e319862d2
--- /dev/null
+++ b/scripts/atomic/fallbacks/read_acquire
@@ -0,0 +1,12 @@
+cat <<EOF
+	${int} ret;
+
+	if (__native_word(${atomic}_t)) {
+		ret = smp_load_acquire(&(v)->counter);
+	} else {
+		ret = raw_${atomic}_read(v);
+		__atomic_acquire_fence();
+	}
+
+	return ret;
+EOF
diff --git a/scripts/atomic/fallbacks/release b/scripts/atomic/fallbacks/release
new file mode 100755
index 000000000..1e6daf57b
--- /dev/null
+++ b/scripts/atomic/fallbacks/release
@@ -0,0 +1,4 @@
+cat <<EOF
+	__atomic_release_fence();
+	${retstmt}arch_${atomic}_${pfx}${name}${sfx}_relaxed(${args});
+EOF
diff --git a/scripts/atomic/fallbacks/set_release b/scripts/atomic/fallbacks/set_release
new file mode 100755
index 000000000..16a374ae6
--- /dev/null
+++ b/scripts/atomic/fallbacks/set_release
@@ -0,0 +1,8 @@
+cat <<EOF
+	if (__native_word(${atomic}_t)) {
+		smp_store_release(&(v)->counter, i);
+	} else {
+		__atomic_release_fence();
+		raw_${atomic}_set(v, i);
+	}
+EOF
diff --git a/scripts/atomic/fallbacks/sub_and_test b/scripts/atomic/fallbacks/sub_and_test
new file mode 100755
index 000000000..d1f746fe0
--- /dev/null
+++ b/scripts/atomic/fallbacks/sub_and_test
@@ -0,0 +1,3 @@
+cat <<EOF
+	return raw_${atomic}_sub_return(i, v) == 0;
+EOF
diff --git a/scripts/atomic/fallbacks/try_cmpxchg b/scripts/atomic/fallbacks/try_cmpxchg
new file mode 100755
index 000000000..d4da82092
--- /dev/null
+++ b/scripts/atomic/fallbacks/try_cmpxchg
@@ -0,0 +1,7 @@
+cat <<EOF
+	${int} r, o = *old;
+	r = raw_${atomic}_cmpxchg${order}(v, o, new);
+	if (unlikely(r != o))
+		*old = r;
+	return likely(r == o);
+EOF
diff --git a/scripts/atomic/fallbacks/xchg b/scripts/atomic/fallbacks/xchg
new file mode 100644
index 000000000..e4def1e0d
--- /dev/null
+++ b/scripts/atomic/fallbacks/xchg
@@ -0,0 +1,3 @@
+cat <<EOF
+	return raw_xchg${order}(&v->counter, new);
+EOF