[tip:perf/core] perf test: Add libbpf relocation checker
From: tip-bot for Wang Nan
Date: Wed Feb 03 2016 - 05:15:09 EST
Commit-ID: 7b6982ce4b38ecc3f63be46beb7bd079aa290fd7
Gitweb: http://git.kernel.org/tip/7b6982ce4b38ecc3f63be46beb7bd079aa290fd7
Author: Wang Nan <wangnan0@xxxxxxxxxx>
AuthorDate: Mon, 25 Jan 2016 09:55:48 +0000
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 26 Jan 2016 12:10:55 -0300
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 <wangnan0@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/r/1453715801-7732-2-git-send-email-wangnan0@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/Makefile.perf | 2 +-
tools/perf/tests/.gitignore | 1 +
tools/perf/tests/Build | 9 ++++++-
...ript-example.c => bpf-script-test-relocation.c} | 30 ++++++++++++----------
tools/perf/tests/bpf.c | 26 +++++++++++++++----
tools/perf/tests/llvm.c | 17 +++++++++---
tools/perf/tests/llvm.h | 5 +++-
7 files changed, 64 insertions(+), 26 deletions(-)
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 5d34815..97ce869 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -618,7 +618,7 @@ clean: $(LIBTRACEEVENT)-clean $(LIBAPI)-clean $(LIBBPF)-clean $(LIBSUBCMD)-clean
$(call QUIET_CLEAN, core-progs) $(RM) $(ALL_PROGRAMS) perf perf-read-vdso32 perf-read-vdsox32
$(call QUIET_CLEAN, core-gen) $(RM) *.spec *.pyc *.pyo */*.pyc */*.pyo $(OUTPUT)common-cmds.h TAGS tags cscope* $(OUTPUT)PERF-VERSION-FILE $(OUTPUT)FEATURE-DUMP $(OUTPUT)util/*-bison* $(OUTPUT)util/*-flex* \
$(OUTPUT)util/intel-pt-decoder/inat-tables.c $(OUTPUT)fixdep \
- $(OUTPUT)tests/llvm-src-{base,kbuild,prologue}.c
+ $(OUTPUT)tests/llvm-src-{base,kbuild,prologue,relocation}.c
$(QUIET_SUBDIR0)Documentation $(QUIET_SUBDIR1) clean
$(python-clean)
diff --git a/tools/perf/tests/.gitignore b/tools/perf/tests/.gitignore
index bf016c4..8cc30e7 100644
--- a/tools/perf/tests/.gitignore
+++ b/tools/perf/tests/.gitignore
@@ -1,3 +1,4 @@
llvm-src-base.c
llvm-src-kbuild.c
llvm-src-prologue.c
+llvm-src-relocation.c
diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index 614899b..1ba628e 100644
--- a/tools/perf/tests/Build
+++ b/tools/perf/tests/Build
@@ -31,7 +31,7 @@ perf-y += sample-parsing.o
perf-y += parse-no-sample-id-all.o
perf-y += kmod-path.o
perf-y += thread-map.o
-perf-y += llvm.o llvm-src-base.o llvm-src-kbuild.o llvm-src-prologue.o
+perf-y += llvm.o llvm-src-base.o llvm-src-kbuild.o llvm-src-prologue.o llvm-src-relocation.o
perf-y += bpf.o
perf-y += topology.o
perf-y += cpumap.o
@@ -59,6 +59,13 @@ $(OUTPUT)tests/llvm-src-prologue.c: tests/bpf-script-test-prologue.c tests/Build
$(Q)sed -e 's/"/\\"/g' -e 's/\(.*\)/"\1\\n"/g' $< >> $@
$(Q)echo ';' >> $@
+$(OUTPUT)tests/llvm-src-relocation.c: tests/bpf-script-test-relocation.c tests/Build
+ $(call rule_mkdir)
+ $(Q)echo '#include <tests/llvm.h>' > $@
+ $(Q)echo 'const char test_llvm__bpf_test_relocation[] =' >> $@
+ $(Q)sed -e 's/"/\\"/g' -e 's/\(.*\)/"\1\\n"/g' $< >> $@
+ $(Q)echo ';' >> $@
+
ifeq ($(ARCH),$(filter $(ARCH),x86 arm arm64))
perf-$(CONFIG_DWARF_UNWIND) += dwarf-unwind.o
endif
diff --git a/tools/perf/tests/bpf-script-example.c b/tools/perf/tests/bpf-script-test-relocation.c
similarity index 69%
copy from tools/perf/tests/bpf-script-example.c
copy to tools/perf/tests/bpf-script-test-relocation.c
index 0ec9c2c..93af774 100644
--- a/tools/perf/tests/bpf-script-example.c
+++ b/tools/perf/tests/bpf-script-test-relocation.c
@@ -1,6 +1,6 @@
/*
- * bpf-script-example.c
- * Test basic LLVM building
+ * bpf-script-test-relocation.c
+ * Test BPF loader checking relocation
*/
#ifndef LINUX_VERSION_CODE
# error Need LINUX_VERSION_CODE
@@ -24,25 +24,27 @@ struct bpf_map_def {
};
#define SEC(NAME) __attribute__((section(NAME), used))
-struct bpf_map_def SEC("maps") flip_table = {
+struct bpf_map_def SEC("maps") my_table = {
.type = BPF_MAP_TYPE_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(int),
.max_entries = 1,
};
-SEC("func=sys_epoll_pwait")
-int bpf_func__sys_epoll_pwait(void *ctx)
+int this_is_a_global_val;
+
+SEC("func=sys_write")
+int bpf_func__sys_write(void *ctx)
{
- int ind =0;
- int *flag = bpf_map_lookup_elem(&flip_table, &ind);
- int new_flag;
- if (!flag)
- return 0;
- /* flip flag and store back */
- new_flag = !*flag;
- bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY);
- return new_flag;
+ int key = 0;
+ int value = 0;
+
+ /*
+ * Incorrect relocation. Should not allow this program be
+ * loaded into kernel.
+ */
+ bpf_map_update_elem(&this_is_a_global_val, &key, &value, 0);
+ return 0;
}
char _license[] SEC("license") = "GPL";
int _version SEC("version") = LINUX_VERSION_CODE;
diff --git a/tools/perf/tests/bpf.c b/tools/perf/tests/bpf.c
index 33689a0..952ca99 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;
diff --git a/tools/perf/tests/llvm.c b/tools/perf/tests/llvm.c
index 06f45c1..70edcdf 100644
--- a/tools/perf/tests/llvm.c
+++ b/tools/perf/tests/llvm.c
@@ -35,6 +35,7 @@ static int test__bpf_parsing(void *obj_buf __maybe_unused,
static struct {
const char *source;
const char *desc;
+ bool should_load_fail;
} bpf_source_table[__LLVM_TESTCASE_MAX] = {
[LLVM_TESTCASE_BASE] = {
.source = test_llvm__bpf_base_prog,
@@ -48,14 +49,19 @@ static struct {
.source = test_llvm__bpf_test_prologue_prog,
.desc = "Compile source for BPF prologue generation test",
},
+ [LLVM_TESTCASE_BPF_RELOCATION] = {
+ .source = test_llvm__bpf_test_relocation,
+ .desc = "Compile source for BPF relocation test",
+ .should_load_fail = true,
+ },
};
-
int
test_llvm__fetch_bpf_obj(void **p_obj_buf,
size_t *p_obj_buf_sz,
enum test_llvm__testcase idx,
- bool force)
+ bool force,
+ bool *should_load_fail)
{
const char *source;
const char *desc;
@@ -68,6 +74,8 @@ test_llvm__fetch_bpf_obj(void **p_obj_buf,
source = bpf_source_table[idx].source;
desc = bpf_source_table[idx].desc;
+ if (should_load_fail)
+ *should_load_fail = bpf_source_table[idx].should_load_fail;
perf_config(perf_config_cb, NULL);
@@ -136,14 +144,15 @@ int test__llvm(int subtest)
int ret;
void *obj_buf = NULL;
size_t obj_buf_sz = 0;
+ bool should_load_fail = false;
if ((subtest < 0) || (subtest >= __LLVM_TESTCASE_MAX))
return TEST_FAIL;
ret = test_llvm__fetch_bpf_obj(&obj_buf, &obj_buf_sz,
- subtest, false);
+ subtest, false, &should_load_fail);
- if (ret == TEST_OK) {
+ if (ret == TEST_OK && !should_load_fail) {
ret = test__bpf_parsing(obj_buf, obj_buf_sz);
if (ret != TEST_OK) {
pr_debug("Failed to parse test case '%s'\n",
diff --git a/tools/perf/tests/llvm.h b/tools/perf/tests/llvm.h
index 5150b4d..0eaa604 100644
--- a/tools/perf/tests/llvm.h
+++ b/tools/perf/tests/llvm.h
@@ -7,14 +7,17 @@
extern const char test_llvm__bpf_base_prog[];
extern const char test_llvm__bpf_test_kbuild_prog[];
extern const char test_llvm__bpf_test_prologue_prog[];
+extern const char test_llvm__bpf_test_relocation[];
enum test_llvm__testcase {
LLVM_TESTCASE_BASE,
LLVM_TESTCASE_KBUILD,
LLVM_TESTCASE_BPF_PROLOGUE,
+ LLVM_TESTCASE_BPF_RELOCATION,
__LLVM_TESTCASE_MAX,
};
int test_llvm__fetch_bpf_obj(void **p_obj_buf, size_t *p_obj_buf_sz,
- enum test_llvm__testcase index, bool force);
+ enum test_llvm__testcase index, bool force,
+ bool *should_load_fail);
#endif