From 7b6982ce4b38ecc3f63be46beb7bd079aa290fd7 Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Mon, 25 Jan 2016 09:55:48 +0000 Subject: perf test: Add libbpf relocation checker There's a bug in LLVM that it can generate unneeded relocation information. See [1] and [2]. Libbpf should check the target section of a relocation symbol. This patch adds a testcase which references a global variable (BPF doesn't support global variables). Before fixing libbpf, the new test case can be loaded into kernel, the global variable acts like the first map. It is incorrect. Result: # ~/perf test BPF 37: Test BPF filter : 37.1: Test basic BPF filtering : Ok 37.2: Test BPF prologue generation : Ok 37.3: Test BPF relocation checker : FAILED! # ~/perf test -v BPF ... libbpf: loading object '[bpf_relocation_test]' from buffer libbpf: section .strtab, size 126, link 0, flags 0, type=3 libbpf: section .text, size 0, link 0, flags 6, type=1 libbpf: section .data, size 0, link 0, flags 3, type=1 libbpf: section .bss, size 0, link 0, flags 3, type=8 libbpf: section func=sys_write, size 104, link 0, flags 6, type=1 libbpf: found program func=sys_write libbpf: section .relfunc=sys_write, size 16, link 10, flags 0, type=9 libbpf: section maps, size 16, link 0, flags 3, type=1 libbpf: maps in [bpf_relocation_test]: 16 bytes libbpf: section license, size 4, link 0, flags 3, type=1 libbpf: license of [bpf_relocation_test] is GPL libbpf: section version, size 4, link 0, flags 3, type=1 libbpf: kernel version of [bpf_relocation_test] is 40400 libbpf: section .symtab, size 144, link 1, flags 0, type=2 libbpf: map 0 is "my_table" libbpf: collecting relocating info for: 'func=sys_write' libbpf: relocation: insn_idx=7 Success unexpectedly: libbpf error when dealing with relocation test child finished with -1 ---- end ---- Test BPF filter subtest 2: FAILED! [1] https://llvm.org/bugs/show_bug.cgi?id=26243 [2] https://patchwork.ozlabs.org/patch/571385/ Signed-off-by: Wang Nan Tested-by: Arnaldo Carvalho de Melo Cc: "David S. Miller" Cc: Alexei Starovoitov Cc: Brendan Gregg Cc: Daniel Borkmann Cc: He Kuang Cc: Jiri Olsa Cc: Li Zefan Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Will Deacon Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1453715801-7732-2-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/tests/bpf.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) (limited to 'tools/perf/tests/bpf.c') diff --git a/tools/perf/tests/bpf.c b/tools/perf/tests/bpf.c index 33689a0cf821..952ca99aba6b 100644 --- a/tools/perf/tests/bpf.c +++ b/tools/perf/tests/bpf.c @@ -71,6 +71,15 @@ static struct { (NR_ITERS + 1) / 4, }, #endif + { + LLVM_TESTCASE_BPF_RELOCATION, + "Test BPF relocation checker", + "[bpf_relocation_test]", + "fix 'perf test LLVM' first", + "libbpf error when dealing with relocation", + NULL, + 0, + }, }; static int do_test(struct bpf_object *obj, int (*func)(void), @@ -190,7 +199,7 @@ static int __test__bpf(int idx) ret = test_llvm__fetch_bpf_obj(&obj_buf, &obj_buf_sz, bpf_testcase_table[idx].prog_id, - true); + true, NULL); if (ret != TEST_OK || !obj_buf || !obj_buf_sz) { pr_debug("Unable to get BPF object, %s\n", bpf_testcase_table[idx].msg_compile_fail); @@ -202,14 +211,21 @@ static int __test__bpf(int idx) obj = prepare_bpf(obj_buf, obj_buf_sz, bpf_testcase_table[idx].name); - if (!obj) { + if ((!!bpf_testcase_table[idx].target_func) != (!!obj)) { + if (!obj) + pr_debug("Fail to load BPF object: %s\n", + bpf_testcase_table[idx].msg_load_fail); + else + pr_debug("Success unexpectedly: %s\n", + bpf_testcase_table[idx].msg_load_fail); ret = TEST_FAIL; goto out; } - ret = do_test(obj, - bpf_testcase_table[idx].target_func, - bpf_testcase_table[idx].expect_result); + if (obj) + ret = do_test(obj, + bpf_testcase_table[idx].target_func, + bpf_testcase_table[idx].expect_result); out: bpf__clear(); return ret; -- cgit v1.2.3