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linux/tools/perf/tests/llvm.c
Wang Nan 7b6982ce4b 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@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
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 <acme@redhat.com>
2016-01-26 12:10:55 -03:00

179 lines
4.1 KiB
C

#include <stdio.h>
#include <bpf/libbpf.h>
#include <util/llvm-utils.h>
#include <util/cache.h>
#include "llvm.h"
#include "tests.h"
#include "debug.h"
static int perf_config_cb(const char *var, const char *val,
void *arg __maybe_unused)
{
return perf_default_config(var, val, arg);
}
#ifdef HAVE_LIBBPF_SUPPORT
static int test__bpf_parsing(void *obj_buf, size_t obj_buf_sz)
{
struct bpf_object *obj;
obj = bpf_object__open_buffer(obj_buf, obj_buf_sz, NULL);
if (IS_ERR(obj))
return TEST_FAIL;
bpf_object__close(obj);
return TEST_OK;
}
#else
static int test__bpf_parsing(void *obj_buf __maybe_unused,
size_t obj_buf_sz __maybe_unused)
{
pr_debug("Skip bpf parsing\n");
return TEST_OK;
}
#endif
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,
.desc = "Basic BPF llvm compiling test",
},
[LLVM_TESTCASE_KBUILD] = {
.source = test_llvm__bpf_test_kbuild_prog,
.desc = "Test kbuild searching",
},
[LLVM_TESTCASE_BPF_PROLOGUE] = {
.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 *should_load_fail)
{
const char *source;
const char *desc;
const char *tmpl_old, *clang_opt_old;
char *tmpl_new = NULL, *clang_opt_new = NULL;
int err, old_verbose, ret = TEST_FAIL;
if (idx >= __LLVM_TESTCASE_MAX)
return TEST_FAIL;
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);
/*
* Skip this test if user's .perfconfig doesn't set [llvm] section
* and clang is not found in $PATH, and this is not perf test -v
*/
if (!force && (verbose == 0 &&
!llvm_param.user_set_param &&
llvm__search_clang())) {
pr_debug("No clang and no verbosive, skip this test\n");
return TEST_SKIP;
}
/*
* llvm is verbosity when error. Suppress all error output if
* not 'perf test -v'.
*/
old_verbose = verbose;
if (verbose == 0)
verbose = -1;
*p_obj_buf = NULL;
*p_obj_buf_sz = 0;
if (!llvm_param.clang_bpf_cmd_template)
goto out;
if (!llvm_param.clang_opt)
llvm_param.clang_opt = strdup("");
err = asprintf(&tmpl_new, "echo '%s' | %s%s", source,
llvm_param.clang_bpf_cmd_template,
old_verbose ? "" : " 2>/dev/null");
if (err < 0)
goto out;
err = asprintf(&clang_opt_new, "-xc %s", llvm_param.clang_opt);
if (err < 0)
goto out;
tmpl_old = llvm_param.clang_bpf_cmd_template;
llvm_param.clang_bpf_cmd_template = tmpl_new;
clang_opt_old = llvm_param.clang_opt;
llvm_param.clang_opt = clang_opt_new;
err = llvm__compile_bpf("-", p_obj_buf, p_obj_buf_sz);
llvm_param.clang_bpf_cmd_template = tmpl_old;
llvm_param.clang_opt = clang_opt_old;
verbose = old_verbose;
if (err)
goto out;
ret = TEST_OK;
out:
free(tmpl_new);
free(clang_opt_new);
if (ret != TEST_OK)
pr_debug("Failed to compile test case: '%s'\n", desc);
return ret;
}
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, &should_load_fail);
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",
bpf_source_table[subtest].desc);
}
}
free(obj_buf);
return ret;
}
int test__llvm_subtest_get_nr(void)
{
return __LLVM_TESTCASE_MAX;
}
const char *test__llvm_subtest_get_desc(int subtest)
{
if ((subtest < 0) || (subtest >= __LLVM_TESTCASE_MAX))
return NULL;
return bpf_source_table[subtest].desc;
}