selftests/bpf: Workaround for llvm nop-4 bug

Currently LLVM fails to recognize .data.* as data section and defaults to .text
section. Later BPF backend tries to emit 4-byte NOP instruction which doesn't
exist in BPF ISA and aborts.
The fix for LLVM is pending:
https://reviews.llvm.org/D138477

While waiting for the fix lets workaround the linked_list test case
by using .bss.* prefix which is properly recognized by LLVM as BSS section.

Fix libbpf to support .bss. prefix and adjust tests.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b5df6aca06eae21c944751e4135ca8ac7cc9f159..93ccea2383917e5306518067c0235c1a9403e57a 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3511,7 +3511,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
                        sec_desc->sec_type = SEC_RELO;
                        sec_desc->shdr = sh;
                        sec_desc->data = data;
-               } else if (sh->sh_type == SHT_NOBITS && strcmp(name, BSS_SEC) == 0) {
+               } else if (sh->sh_type == SHT_NOBITS && (strcmp(name, BSS_SEC) == 0 ||
+                                                        str_has_pfx(name, BSS_SEC "."))) {
                        sec_desc->sec_type = SEC_BSS;
                        sec_desc->shdr = sh;
                        sec_desc->data = data;

diff --git a/tools/testing/selftests/bpf/prog_tests/linked_list.c b/tools/testing/selftests/bpf/prog_tests/linked_list.c
index dd73d0a62c6ea64d98ddc753edf3bb29668147d5..9a7d4c47af63315be45307e7818aa6a58cdaa8e9 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/linked_list.c
+++ b/tools/testing/selftests/bpf/prog_tests/linked_list.c
@@ -189,7 +189,7 @@ static void test_linked_list_success(int mode, bool leave_in_map)
        ASSERT_OK(ret, "global_list_push_pop");
        ASSERT_OK(opts.retval, "global_list_push_pop retval");
        if (!leave_in_map)
-               clear_fields(skel->maps.data_A);
+               clear_fields(skel->maps.bss_A);
 
        if (mode == PUSH_POP)
                goto end;
@@ -211,7 +211,7 @@ ppm:
        ASSERT_OK(ret, "global_list_push_pop_multiple");
        ASSERT_OK(opts.retval, "global_list_push_pop_multiple retval");
        if (!leave_in_map)
-               clear_fields(skel->maps.data_A);
+               clear_fields(skel->maps.bss_A);
 
        if (mode == PUSH_POP_MULT)
                goto end;
@@ -233,7 +233,7 @@ lil:
        ASSERT_OK(ret, "global_list_in_list");
        ASSERT_OK(opts.retval, "global_list_in_list retval");
        if (!leave_in_map)
-               clear_fields(skel->maps.data_A);
+               clear_fields(skel->maps.bss_A);
 end:
        linked_list__destroy(skel);
 }

diff --git a/tools/testing/selftests/bpf/progs/linked_list.h b/tools/testing/selftests/bpf/progs/linked_list.h
index 8db80ed64db1b0e3aed989f557addeab586e4776..3fb2412552fc74df675ecdbc819713957d6902a9 100644 (file)
--- a/tools/testing/selftests/bpf/progs/linked_list.h
+++ b/tools/testing/selftests/bpf/progs/linked_list.h
@@ -47,7 +47,7 @@ struct {
        },
 };
 
-#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8)))
+#define private(name) SEC(".bss." #name) __hidden __attribute__((aligned(8)))
 
 private(A) struct bpf_spin_lock glock;
 private(A) struct bpf_list_head ghead __contains(foo, node);