[PATCH bpf-next v1 7/7] selftests/bpf: Test timed may_goto with private stacks

[Siddharth Chintamaneni <sidchintamaneni@gmail.com>]

Add private_stack_timed_may_goto() with enough stack usage to select a
private stack. Check that the JIT uses the private-stack frame pointer
when constructing the pointer passed to the architecture trampoline.

Update the translated instruction expectations in may_goto_batch_2(),
may_goto_interaction_x86_64(), and may_goto_interaction() for the
additional pointer construction instruction and adjusted branch offsets.

Signed-off-by: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
---
 .../bpf/progs/verifier_bpf_fastcall.c         | 30 ++++++++++---------
 .../selftests/bpf/progs/verifier_may_goto_1.c | 17 ++++++-----
 .../bpf/progs/verifier_private_stack.c        | 19 ++++++++++++
 3 files changed, 44 insertions(+), 22 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/verifier_bpf_fastcall.c b/tools/testing/selftests/bpf/progs/verifier_bpf_fastcall.c
index 328cf630210a..c5996d9dc8cc 100644
--- a/tools/testing/selftests/bpf/progs/verifier_bpf_fastcall.c
+++ b/tools/testing/selftests/bpf/progs/verifier_bpf_fastcall.c
@@ -635,15 +635,16 @@ __xlated("4: r0 = &(void __percpu *)(r0)")
 __xlated("...")
 /* may_goto expansion starts */
 __xlated("6: r12 = *(u64 *)(r10 -24)")
-__xlated("7: if r12 == 0x0 goto pc+6")
+__xlated("7: if r12 == 0x0 goto pc+7")
 __xlated("8: r12 -= 1")
-__xlated("9: if r12 != 0x0 goto pc+2")
-__xlated("10: r12 = -24")
-__xlated("11: call unknown")
-__xlated("12: *(u64 *)(r10 -24) = r12")
+__xlated("9: if r12 != 0x0 goto pc+3")
+__xlated("10: r12 = r10")
+__xlated("11: r12 += -24")
+__xlated("12: call unknown")
+__xlated("13: *(u64 *)(r10 -24) = r12")
 /* may_goto expansion ends */
-__xlated("13: *(u64 *)(r10 -8) = r1")
-__xlated("14: exit")
+__xlated("14: *(u64 *)(r10 -8) = r1")
+__xlated("15: exit")
 __success
 __naked void may_goto_interaction_x86_64(void)
 {
@@ -676,15 +677,16 @@ __xlated("2: r1 = 1")
 __xlated("3: call bpf_get_smp_processor_id")
 /* may_goto expansion starts */
 __xlated("4: r12 = *(u64 *)(r10 -24)")
-__xlated("5: if r12 == 0x0 goto pc+6")
+__xlated("5: if r12 == 0x0 goto pc+7")
 __xlated("6: r12 -= 1")
-__xlated("7: if r12 != 0x0 goto pc+2")
-__xlated("8: r12 = -24")
-__xlated("9: call unknown")
-__xlated("10: *(u64 *)(r10 -24) = r12")
+__xlated("7: if r12 != 0x0 goto pc+3")
+__xlated("8: r12 = r10")
+__xlated("9: r12 += -24")
+__xlated("10: call unknown")
+__xlated("11: *(u64 *)(r10 -24) = r12")
 /* may_goto expansion ends */
-__xlated("11: *(u64 *)(r10 -8) = r1")
-__xlated("12: exit")
+__xlated("12: *(u64 *)(r10 -8) = r1")
+__xlated("13: exit")
 __success
 __naked void may_goto_interaction(void)
 {
diff --git a/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c b/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c
index db7e30da234f..1721897160dc 100644
--- a/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c
+++ b/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c
@@ -90,15 +90,16 @@ __arch_loongarch
 __xlated("0: *(u64 *)(r10 -16) = 65535")
 __xlated("1: *(u64 *)(r10 -8) = 0")
 __xlated("2: r12 = *(u64 *)(r10 -16)")
-__xlated("3: if r12 == 0x0 goto pc+6")
+__xlated("3: if r12 == 0x0 goto pc+7")
 __xlated("4: r12 -= 1")
-__xlated("5: if r12 != 0x0 goto pc+2")
-__xlated("6: r12 = -16")
-__xlated("7: call unknown")
-__xlated("8: *(u64 *)(r10 -16) = r12")
-__xlated("9: r0 = 1")
-__xlated("10: r0 = 2")
-__xlated("11: exit")
+__xlated("5: if r12 != 0x0 goto pc+3")
+__xlated("6: r12 = r10")
+__xlated("7: r12 += -16")
+__xlated("8: call unknown")
+__xlated("9: *(u64 *)(r10 -16) = r12")
+__xlated("10: r0 = 1")
+__xlated("11: r0 = 2")
+__xlated("12: exit")
 __success
 __naked void may_goto_batch_2(void)
 {
diff --git a/tools/testing/selftests/bpf/progs/verifier_private_stack.c b/tools/testing/selftests/bpf/progs/verifier_private_stack.c
index 3d9994a52464..639b53363c9a 100644
--- a/tools/testing/selftests/bpf/progs/verifier_private_stack.c
+++ b/tools/testing/selftests/bpf/progs/verifier_private_stack.c
@@ -70,6 +70,25 @@ __naked void no_private_stack_nested(void)
 "	::: __clobber_all);
 }
 
+SEC("fentry/bpf_fentry_test9")
+__description("Private stack, timed may_goto")
+__success __retval(0)
+__arch_x86_64
+__jited("	movabsq	$0x{{.*}}, %r9")
+__jited("...")
+__jited("	movq	%r9, %r10")
+__arch_arm64
+__jited("	mov	x9, x25")
+int private_stack_timed_may_goto(void)
+{
+	volatile __u64 stack_space[16] = {};
+
+	while (can_loop)
+		;
+
+	return stack_space[0];
+}
+
 __used
 __naked static void cumulative_stack_depth_subprog(void)
 {
-- 
2.43.0


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