[PATCH bpf-next 5/7] selftests/bpf: Add arm64 JIT-sequence tests for __arena kfunc arguments

[Puranjay Mohan <puranjay@kernel.org>]

Pin the arm64 counterparts of the x86-64 rebase sequences: the single
extended-register add for an unconditional argument, the nullable
truncate-test-and-skip variant, and all five argument registers in one
call. The nullable cases use a local label so the branch is pinned to
the instruction right after the add, and the label line does not spell
out the call because arm64 emits either a direct bl or a materialize-
and-blr pair depending on the distance to the kfunc.

Note that on arm64 an unconditional argument is one instruction with
nothing to anchor it against, so arena_arg_jit_rebase alone cannot tell
the two forms apart; it only requires that nothing is emitted between
the rebase and the call. The args5 test is what pins the distinction,
since its four consecutive adds leave no room for a nullable
truncate-and-branch pair between them.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
---
 .../selftests/bpf/progs/arena_kfunc_jit.c     | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/arena_kfunc_jit.c b/tools/testing/selftests/bpf/progs/arena_kfunc_jit.c
index c9b9186626162..b5a01cbc33a73 100644
--- a/tools/testing/selftests/bpf/progs/arena_kfunc_jit.c
+++ b/tools/testing/selftests/bpf/progs/arena_kfunc_jit.c
@@ -32,6 +32,10 @@ __jited("	movl	%edi, %edi")
 __jited("	addq	%r12, %rdi")
 __jited("...")
 __jited("	callq	{{.*}}")
+__arch_arm64
+__jited("...")
+__jited("	add	x0, x28, w0, uxtw")
+__jited("	{{(bl|mov)	.*}}")
 __success
 int arena_arg_jit_rebase(void *ctx)
 {
@@ -48,6 +52,12 @@ __jited("	testl	%edi, %edi")
 __jited("	je	L0")
 __jited("	addq	%r12, %rdi")
 __jited("L0:	callq	{{.*}}")
+__arch_arm64
+__jited("...")
+__jited("	mov	w0, w0")
+__jited("	cbz	w0, L0")
+__jited("	add	x0, x28, w0, uxtw")
+__jited("L0:	{{.*}}")
 __success
 int arena_arg_jit_nullable(void *ctx)
 {
@@ -72,6 +82,16 @@ __jited("	testl	%r8d, %r8d")
 __jited("	je	L0")
 __jited("	addq	%r12, %r8")
 __jited("L0:	callq	{{.*}}")
+__arch_arm64
+__jited("...")
+__jited("	add	x0, x28, w0, uxtw")
+__jited("	add	x1, x28, w1, uxtw")
+__jited("	add	x2, x28, w2, uxtw")
+__jited("	add	x3, x28, w3, uxtw")
+__jited("	mov	w4, w4")
+__jited("	cbz	w4, L0")
+__jited("	add	x4, x28, w4, uxtw")
+__jited("L0:	{{.*}}")
 __success
 int arena_arg_jit_args5(void *ctx)
 {
-- 
2.53.0-Meta