Cover the arm64 even-register rule for 16-byte aligned arguments:
f_even() and f_stack() where the rule does not bite, f_odd() and
f_odd_tail() where it leaves a register hole, and f_box() where the
alignment comes from a struct member rather than from the parameter
type itself.

The test results on arm64:
  $ VERBOSE=1 ./clang_parm_align16.sh
  Validation of BTF encoding of over-aligned arguments.
     BTF: u64 f_even(u64 a, u64 b, __int128 v);
     BTF: u64 f_odd(u64 a, __int128 v, u64 b);
     BTF: u64 f_odd_tail(u64 a, __int128 v, u64 b, u64 c, u64 d);
     BTF: u64 f_stack(u64 a, u64 b, u64 c, u64 d, u64 e, u64 f, u64 g, __int128 v);
     BTF: u64 f_box(u64 a, struct box s, u64 b);
  Test ./clang_parm_align16.sh passed

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
 tests/clang_parm_align16.sh | 77 +++++++++++++++++++++++++++++++++++++
 tests/test_lib.sh           |  3 +-
 2 files changed, 78 insertions(+), 2 deletions(-)
 create mode 100755 tests/clang_parm_align16.sh

diff --git a/tests/clang_parm_align16.sh b/tests/clang_parm_align16.sh
new file mode 100755
index 0000000..484aeb6
--- /dev/null
+++ b/tests/clang_parm_align16.sh
@@ -0,0 +1,77 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-only
+
+source test_lib.sh
+
+outdir=$(make_tmpdir)
+
+# Comment this out to save test data.
+trap cleanup EXIT
+
+title_log "Validation of BTF encoding of over-aligned arguments."
+
+align16="${outdir}/align16"
+CC=$(which clang 2>/dev/null)
+
+if [[ -z "$CC" ]]; then
+	info_log "skip: clang not available"
+	test_skip
+fi
+
+arch=$(uname -m)
+if [[ "$arch" != "aarch64" ]]; then
+	info_log "skip: test is arm64 only, running on $arch"
+	test_skip
+fi
+
+# arm64 makes an argument whose alignment is 16 start on an even-numbered
+# argument register, so f_odd() passes a in x0, v in x2:x3 -- leaving x1 as a
+# hole -- and b in x4.  pahole has to account for that hole, otherwise every
+# parameter after v looks like it is in an unexpected register and the whole
+# function is dropped from BTF.
+cat > ${align16}.c << EOF
+typedef unsigned long long u64;
+struct box { __int128 v; };
+
+__attribute__((noinline)) u64 f_even(u64 a, u64 b, __int128 v)
+{ return a + b + (u64)v; }
+
+__attribute__((noinline)) u64 f_odd(u64 a, __int128 v, u64 b)
+{ return a + b + (u64)v; }
+
+__attribute__((noinline)) u64 f_odd_tail(u64 a, __int128 v, u64 b, u64 c, u64 d)
+{ return a + b + c + d + (u64)v; }
+
+__attribute__((noinline)) u64 f_stack(u64 a, u64 b, u64 c, u64 d, u64 e, u64 f,
+				      u64 g, __int128 v)
+{ return a + b + c + d + e + f + g + (u64)v; }
+
+__attribute__((noinline)) u64 f_box(u64 a, struct box s, u64 b)
+{ return a + b + (u64)s.v; }
+
+u64 (*keep[])() = { (u64(*)())f_even, (u64(*)())f_odd, (u64(*)())f_odd_tail,
+		    (u64(*)())f_stack, (u64(*)())f_box };
+EOF
+
+${CC} -g -O2 -c -o ${align16}.o ${align16}.c 2>/dev/null
+if [[ $? -ne 0 ]]; then
+	info_log "skip: clang could not compile ${align16}.c"
+	test_skip
+fi
+
+LLVM_OBJCOPY=objcopy pahole -J --btf_features=consistent_func ${align16}.o
+if [[ $? -ne 0 ]]; then
+	error_log "Could not encode BTF for ${align16}.o"
+	test_fail
+fi
+
+for fn in f_even f_odd f_odd_tail f_stack f_box; do
+	encoded=$(pfunct --all --format_path=btf ${align16}.o | grep " ${fn}(")
+	verbose_log "BTF: $encoded"
+	if [[ -z "$encoded" ]]; then
+		error_log "${fn}() is missing from BTF"
+		test_fail
+	fi
+done
+
+test_pass
diff --git a/tests/test_lib.sh b/tests/test_lib.sh
index e2a7218..e2d0b0c 100755
--- a/tests/test_lib.sh
+++ b/tests/test_lib.sh
@@ -661,8 +661,7 @@ check_bpftool_btf_support()
 cleanup()
 {
 	if [ -n "$outdir" ] && [ -d "$outdir" ]; then
-		rm ${outdir}/*
-		rmdir $outdir
+		rm -rf "$outdir"
 	fi
 	return 0
 }
-- 
2.53.0-Meta