From 71cf4d027ad53a1e2847191ac14e50132d35a6a7 Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Sat, 4 Mar 2023 03:12:47 +0200 Subject: selftests/bpf: Disassembler tests for verifier.c:convert_ctx_access() Function verifier.c:convert_ctx_access() applies some rewrites to BPF instructions that read or write BPF program context. This commit adds machinery to allow test cases that inspect BPF program after these rewrites are applied. An example of a test case: { // Shorthand for field offset and size specification N(CGROUP_SOCKOPT, struct bpf_sockopt, retval), // Pattern generated for field read .read = "$dst = *(u64 *)($ctx + bpf_sockopt_kern::current_task);" "$dst = *(u64 *)($dst + task_struct::bpf_ctx);" "$dst = *(u32 *)($dst + bpf_cg_run_ctx::retval);", // Pattern generated for field write .write = "*(u64 *)($ctx + bpf_sockopt_kern::tmp_reg) = r9;" "r9 = *(u64 *)($ctx + bpf_sockopt_kern::current_task);" "r9 = *(u64 *)(r9 + task_struct::bpf_ctx);" "*(u32 *)(r9 + bpf_cg_run_ctx::retval) = $src;" "r9 = *(u64 *)($ctx + bpf_sockopt_kern::tmp_reg);" , }, For each test case, up to three programs are created: - One that uses BPF_LDX_MEM to read the context field. - One that uses BPF_STX_MEM to write to the context field. - One that uses BPF_ST_MEM to write to the context field. The disassembly of each program is compared with the pattern specified in the test case. Kernel code for disassembly is reused (as is in the bpftool). To keep Makefile changes to the minimum, symbolic links to `kernel/bpf/disasm.c` and `kernel/bpf/disasm.h ` are added. Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20230304011247.566040-4-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/testing/selftests/bpf/Makefile') diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index eab3cf5399f5..16f404aa1b23 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -559,7 +559,7 @@ TRUNNER_BPF_PROGS_DIR := progs TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c \ network_helpers.c testing_helpers.c \ btf_helpers.c flow_dissector_load.h \ - cap_helpers.c test_loader.c xsk.c + cap_helpers.c test_loader.c xsk.c disasm.c TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko \ $(OUTPUT)/liburandom_read.so \ $(OUTPUT)/xdp_synproxy \ -- cgit v1.2.3