[PATCH bpf-next v1 2/2] selftests/bpf: Test invalid DW LDSX diagnostics

[Kumar Kartikeya Dwivedi <memxor@gmail.com>]

An invalid BPF_MEMSX | BPF_DW instruction can reach Program Structure
diagnostics before opcode validation when placed at the end of a subprogram.
Exercise this path and require the disassembler fallback so table bounds
regressions are caught.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 tools/testing/selftests/bpf/progs/verifier_cfg.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_cfg.c b/tools/testing/selftests/bpf/progs/verifier_cfg.c
index c1f55e1d80a4..3c3bb03e8217 100644
--- a/tools/testing/selftests/bpf/progs/verifier_cfg.c
+++ b/tools/testing/selftests/bpf/progs/verifier_cfg.c
@@ -3,6 +3,7 @@
 
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
+#include "../../../include/linux/filter.h"
 #include "bpf_misc.h"
 
 SEC("socket")
@@ -55,6 +56,19 @@ __naked void out_of_range_jump2(void)
 "	::: __clobber_all);
 }
 
+SEC("socket")
+__description("invalid DW LDSX instruction in diagnostics")
+__failure __msg("BUG_ldx_99")
+__log_level(2)
+__naked void invalid_dw_ldsx(void)
+{
+	asm volatile ("					\
+	.8byte %[ldsx_dw];				\
+"	:
+	: __imm_insn(ldsx_dw, BPF_RAW_INSN(BPF_LDX | BPF_MEMSX | BPF_DW, BPF_REG_0, BPF_REG_0, 0, 0))
+	: __clobber_all);
+}
+
 SEC("socket")
 __description("loop (back-edge)")
 __failure __msg("unreachable insn 1")
-- 
2.53.0