Commit dc79f035 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

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: default avatarAlexei Starovoitov <ast@kernel.org>
parent 0b2971a2

tools/lib/bpf/libbpf.c

+2 −1
Original line number Diff line number Diff line
@@ -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;

tools/testing/selftests/bpf/prog_tests/linked_list.c

+3 −3
Original line number Diff line number Diff line
@@ -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 @@ static void test_linked_list_success(int mode, bool leave_in_map) 
	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 @@ static void test_linked_list_success(int mode, bool leave_in_map) 
	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);

}

tools/testing/selftests/bpf/progs/linked_list.h

+1 −1
Original line number Diff line number Diff line
@@ -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);