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, 56 insertions, 0 deletions

diff --git a/arch/arc/lib/memset.S b/arch/arc/lib/memset.S
new file mode 100644
index 000000000..9f35960da
--- /dev/null
+++ b/arch/arc/lib/memset.S
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ */
+
+#include <linux/linkage.h>
+
+#define SMALL	7 /* Must be at least 6 to deal with alignment/loop issues.  */
+
+ENTRY_CFI(memset)
+	mov_s	r4,r0
+	or	r12,r0,r2
+	bmsk.f	r12,r12,1
+	extb_s	r1,r1
+	asl	r3,r1,8
+	beq.d	.Laligned
+	or_s	r1,r1,r3
+	brls	r2,SMALL,.Ltiny
+	add	r3,r2,r0
+	stb	r1,[r3,-1]
+	bclr_s	r3,r3,0
+	stw	r1,[r3,-2]
+	bmsk.f	r12,r0,1
+	add_s	r2,r2,r12
+	sub.ne	r2,r2,4
+	stb.ab	r1,[r4,1]
+	and	r4,r4,-2
+	stw.ab	r1,[r4,2]
+	and	r4,r4,-4
+.Laligned:	; This code address should be aligned for speed.
+	asl	r3,r1,16
+	lsr.f	lp_count,r2,2
+	or_s	r1,r1,r3
+	lpne	.Loop_end
+	st.ab	r1,[r4,4]
+.Loop_end:
+	j_s	[blink]
+
+	.balign	4
+.Ltiny:
+	mov.f	lp_count,r2
+	lpne	.Ltiny_end
+	stb.ab	r1,[r4,1]
+.Ltiny_end:
+	j_s	[blink]
+END_CFI(memset)
+
+; memzero: @r0 = mem, @r1 = size_t
+; memset:  @r0 = mem, @r1 = char, @r2 = size_t
+
+ENTRY_CFI(memzero)
+    ; adjust bzero args to memset args
+    mov r2, r1
+    mov r1, 0
+    b  memset    ;tail call so need to tinker with blink
+END_CFI(memzero)