A simple program that allocates a bunch of unique register ids than
branches. The goal is to confirm that idmap used in verifier.c:check_ids()
has sufficient capacity to verify that branches converge to a same state.
Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
---
.../selftests/bpf/prog_tests/verifier.c | 12 +++
.../selftests/bpf/progs/check_ids_limits.c | 77 +++++++++++++++++++
2 files changed, 89 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/verifier.c
create mode 100644 tools/testing/selftests/bpf/progs/check_ids_limits.c
diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c
new file mode 100644
index 000000000000..3933141928a7
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/verifier.c
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <test_progs.h>
+
+#include "check_ids_limits.skel.h"
+
+#define TEST_SET(skel) \
+ void test_##skel(void) \
+ { \
+ RUN_TESTS(skel); \
+ }
+
+TEST_SET(check_ids_limits)
diff --git a/tools/testing/selftests/bpf/progs/check_ids_limits.c b/tools/testing/selftests/bpf/progs/check_ids_limits.c
new file mode 100644
index 000000000000..36c4a8bbe8ca
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/check_ids_limits.c
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+struct map_struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, int);
+ __type(value, int);
+} map SEC(".maps");
+
+/* Make sure that verifier.c:check_ids() can handle (almost) maximal
+ * number of ids.
+ */
+SEC("?raw_tp")
+__naked __test_state_freq __log_level(2) __msg("43 to 45: safe")
+int allocate_many_ids(void)
+{
+ /* Use bpf_map_lookup_elem() as a way to get a bunch of values
+ * with unique ids.
+ */
+#define __lookup(dst) \
+ "r1 = %[map] ll;" \
+ "r2 = r10;" \
+ "r2 += -8;" \
+ "call %[bpf_map_lookup_elem];" \
+ dst " = r0;"
+ asm volatile(
+ "r0 = 0;"
+ "*(u64*)(r10 - 8) = r0;"
+ "r7 = r10;"
+ "r8 = 0;"
+ /* Spill 64 bpf_map_lookup_elem() results to stack,
+ * each lookup gets its own unique id.
+ */
+ "write_loop:"
+ "r7 += -8;"
+ "r8 += -8;"
+ __lookup("*(u64*)(r7 + 0)")
+ "if r8 != -512 goto write_loop;"
+ /* No way to source unique ids for r1-r5 as these
+ * would be clobbered by bpf_map_lookup_elem call,
+ * so make do with 64+5 unique ids.
+ */
+ __lookup("r6")
+ __lookup("r7")
+ __lookup("r8")
+ __lookup("r9")
+ __lookup("r0")
+ /* Create a branching point for states comparison. */
+/* 43: */ "if r0 != 0 goto skip_one;"
+ /* Read all registers and stack spills to make these
+ * persist in the checkpoint state.
+ */
+ "r0 = r0;"
+ "skip_one:"
+/* 45: */ "r0 = r6;"
+ "r0 = r7;"
+ "r0 = r8;"
+ "r0 = r9;"
+ "r0 = r10;"
+ "r1 = 0;"
+ "read_loop:"
+ "r0 += -8;"
+ "r1 += -8;"
+ "r2 = *(u64*)(r0 + 0);"
+ "if r1 != -512 goto read_loop;"
+ "r0 = 0;"
+ "exit;"
+ :
+ : __imm(bpf_map_lookup_elem),
+ __imm_addr(map)
+ : __clobber_all);
+#undef __lookup
+}
--
2.38.2
