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, 65 insertions, 0 deletions

diff --git a/include/crypto/aes-ctr.h b/include/crypto/aes-ctr.h
new file mode 100644
index 000000000..8e214a857
--- /dev/null
+++ b/include/crypto/aes-ctr.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * AES-CTR and AES-XCTR stream ciphers
+ *
+ * Copyright 2026 Google LLC
+ */
+#ifndef _CRYPTO_AES_CTR_H
+#define _CRYPTO_AES_CTR_H
+
+#include <crypto/aes.h>
+
+/**
+ * aes_ctr() - AES-CTR en/decryption
+ * @dst: The destination buffer.  Can be in-place or out-of-place.  For other
+ *	 overlaps the behavior is unspecified.
+ * @src: The source data
+ * @len: Number of bytes to en/decrypt
+ * @ctr: The counter.  It will be incremented by ceil(@len / AES_BLOCK_SIZE).
+ * @key: The key, already prepared using aes_preparekey() or aes_prepareenckey()
+ *
+ * This implements AES in counter mode with a 128-bit big endian counter.
+ *
+ * This exists only for use by the implementation of modes built on top of CTR
+ * (e.g., GCM and CCM) and some legacy protocols that use CTR mode directly.
+ * Callers are expected to know how to use CTR mode appropriately, including
+ * choosing (key, counter) pairs appropriately to avoid keystream reuse.
+ *
+ * This supports incremental en/decryption.  The length of each non-final chunk
+ * must be a multiple of AES_BLOCK_SIZE, and the updated @ctr must be passed in
+ * each time.
+ *
+ * Context: Any context.
+ */
+void aes_ctr(u8 *dst, const u8 *src, size_t len,
+	     u8 ctr[at_least AES_BLOCK_SIZE], aes_encrypt_arg key);
+
+/**
+ * aes_xctr() - AES-XCTR en/decryption
+ * @dst: The destination buffer.  Can be in-place or out-of-place.  For other
+ *	 overlaps the behavior is unspecified.
+ * @src: The source data
+ * @len: Number of bytes to en/decrypt
+ * @ctr: The block counter (in host endianness).  For the first call, set it to
+ *	 1.  It will be incremented by ceil(@len / AES_BLOCK_SIZE).
+ * @iv: The initialization vector
+ * @key: The key, already prepared using aes_preparekey() or aes_prepareenckey()
+ *
+ * This implements AES in XOR Counter mode, as specified in the paper
+ * "Length-preserving encryption with HCTR2"
+ * (https://eprint.iacr.org/2021/1441.pdf).
+ *
+ * This exists only for use by the implementation of modes built on top of XCTR.
+ * Callers are expected to know how to use XCTR mode appropriately, including
+ * choosing (key, IV) pairs appropriately to avoid keystream reuse.
+ *
+ * This supports incremental en/decryption.  The length of each non-final chunk
+ * must be a multiple of AES_BLOCK_SIZE, and the updated @ctr must be passed in
+ * each time.
+ *
+ * Context: Any context.
+ */
+void aes_xctr(u8 *dst, const u8 *src, size_t len, u64 *ctr,
+	      const u8 iv[at_least AES_BLOCK_SIZE], aes_encrypt_arg key);
+
+#endif /* _CRYPTO_AES_CTR_H */