libbpf: remove linux/unaligned.h dependency for libbpf_sha256()

linux/unaligned.h include dependency is causing issues for libbpf's
Github mirror due to {get,put}_unaligned_be32() usage.

So get rid of it by implementing custom variants of those macros that
will work both in kernel repo and in Github mirror repo.

Also fix switch from round_up() to roundup(), as the former is not
available in Github mirror (and is just a subtle more specific variant
of roundup() anyways).

Signed-off-by: Andrii Nakryiko <[email protected]>

Author: anakryiko

tools/lib/bpf/libbpf_utils.c

@@ -13,7 +13,6 @@
 #include <errno.h>
 #include <inttypes.h>
 #include <linux/kernel.h>
-#include <linux/unaligned.h>
 
 #include "libbpf.h"
 #include "libbpf_internal.h"
@@ -149,6 +148,14 @@ const char *libbpf_errstr(int err)
 	}
 }
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpacked"
+struct __packed_u32 { __u32 __val; } __attribute__((packed));
+#pragma GCC diagnostic pop
+
+#define get_unaligned_be32(p) (((struct __packed_u32 *)(p))->__val)
+#define put_unaligned_be32(v, p) do { ((struct __packed_u32 *)(p))->__val = (v); } while (0)
+
 #define SHA256_BLOCK_LENGTH 64
 #define Ch(x, y, z) (((x) & (y)) ^ (~(x) & (z)))
 #define Maj(x, y, z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
@@ -232,7 +239,7 @@ void libbpf_sha256(const void *data, size_t len, __u8 out[SHA256_DIGEST_LENGTH])
 
 	memcpy(final_data, data + len - final_len, final_len);
 	final_data[final_len] = 0x80;
-	final_len = round_up(final_len + 9, SHA256_BLOCK_LENGTH);
+	final_len = roundup(final_len + 9, SHA256_BLOCK_LENGTH);
 	memcpy(&final_data[final_len - 8], &bitcount, 8);
 
 	sha256_blocks(state, final_data, final_len / SHA256_BLOCK_LENGTH);