Commit-ID: f078464925f5b5c977c1196c67cae49cd82f40ff
Gitweb: http://git.kernel.org/tip/f078464925f5b5c977c1196c67cae49cd82f40ff
Author: Wang Nan <wangn...@huawei.com>
AuthorDate: Thu, 16 Jun 2016 08:02:40 +0000
Committer: Arnaldo Carvalho de Melo <a...@redhat.com>
CommitDate: Tue, 21 Jun 2016 13:18:34 -0300
perf llvm: Allow dump llvm output object file using llvm.dump-obj
Add a 'llvm.dump-obj' config option to enable perf dump BPF object files
compiled by LLVM.
This option is useful when using BPF objects in embedded platforms.
LLVM compiler won't be deployed in these platforms, and currently we
don't support dynamic compiling library.
Before this patch users have to explicitly issue llvm commands to
compile BPF scripts, and can't use helpers (like include path detection
and default macros) in perf. With this option, user is allowed to use
perf to compile their BPF objects then copy them into their embedded
platforms.
Committer notice:
Testing it:
# cat ~/.perfconfig
[llvm]
dump-obj = true
#
# ls -la filter.o
ls: cannot access filter.o: No such file or directory
# cat filter.c
#include <uapi/linux/bpf.h>
#define SEC(NAME) __attribute__((section(NAME), used))
SEC("func=hrtimer_nanosleep rqtp->tv_nsec")
int func(void *ctx, int err, long nsec)
{
return nsec > 1000;
}
char _license[] SEC("license") = "GPL";
int _version SEC("version") = LINUX_VERSION_CODE;
# trace -e nanosleep --event filter.c usleep 6
LLVM: dumping filter.o
0.007 ( 0.007 ms): usleep/13976 nanosleep(rqtp: 0x7ffc5847f640
) ...
0.007 ( ): perf_bpf_probe:func:(ffffffff811137d0) tv_nsec=6000)
0.070 ( 0.070 ms): usleep/13976 ... [continued]: nanosleep()) = 0
# ls -la filter.o
-rw-r--r--. 1 root root 776 Jun 20 17:01 filter.o
# readelf -SW filter.o
There are 7 section headers, starting at offset 0x148:
Section Headers:
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[ 0] NULL 0000000000000000 000000 000000 00 0 0 0
[ 1] .strtab STRTAB 0000000000000000 0000e8 00005a 00 0 0 1
[ 2] .text PROGBITS 0000000000000000 000040 000000 00 AX 0 0 4
[ 3] func=hrtimer_nanosleep rqtp->tv_nsec PROGBITS 0000000000000000 000040
000028 00 AX 0 0 8
[ 4] license PROGBITS 0000000000000000 000068 000004 00 WA 0 0 1
[ 5] version PROGBITS 0000000000000000 00006c 000004 00 WA 0 0 4
[ 6] .symtab SYMTAB 0000000000000000 000070 000078 18 1 2 8
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings)
I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
O (extra OS processing required) o (OS specific), p (processor specific)
#
Signed-off-by: Wang Nan <wangn...@huawei.com>
Cc: Alexei Starovoitov <a...@kernel.org>
Cc: Jiri Olsa <jo...@kernel.org>
Cc: pi3or...@163.com
Link:
http://lkml.kernel.org/r/1466064161-48553-2-git-send-email-wangn...@huawei.com
[ s/dumpping/dumping/g ]
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
---
tools/perf/util/llvm-utils.c | 42 ++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/llvm-utils.h | 5 +++++
2 files changed, 47 insertions(+)
diff --git a/tools/perf/util/llvm-utils.c b/tools/perf/util/llvm-utils.c
index 33071d6..878a566 100644
--- a/tools/perf/util/llvm-utils.c
+++ b/tools/perf/util/llvm-utils.c
@@ -42,6 +42,8 @@ int perf_llvm_config(const char *var, const char *value)
llvm_param.kbuild_dir = strdup(value);
else if (!strcmp(var, "kbuild-opts"))
llvm_param.kbuild_opts = strdup(value);
+ else if (!strcmp(var, "dump-obj"))
+ llvm_param.dump_obj = !!perf_config_bool(var, value);
else
return -1;
llvm_param.user_set_param = true;
@@ -326,6 +328,42 @@ get_kbuild_opts(char **kbuild_dir, char
**kbuild_include_opts)
pr_debug("include option is set to %s\n", *kbuild_include_opts);
}
+static void
+dump_obj(const char *path, void *obj_buf, size_t size)
+{
+ char *obj_path = strdup(path);
+ FILE *fp;
+ char *p;
+
+ if (!obj_path) {
+ pr_warning("WARNING: No enough memory, skip object dumping\n");
+ return;
+ }
+
+ p = strrchr(obj_path, '.');
+ if (!p || (strcmp(p, ".c") != 0)) {
+ pr_warning("WARNING: invalid llvm source path: '%s', skip
object dumping\n",
+ obj_path);
+ goto out;
+ }
+
+ p[1] = 'o';
+ fp = fopen(obj_path, "wb");
+ if (!fp) {
+ pr_warning("WARNING: failed to open '%s': %s, skip object
dumping\n",
+ obj_path, strerror(errno));
+ goto out;
+ }
+
+ pr_info("LLVM: dumping %s\n", obj_path);
+ if (fwrite(obj_buf, size, 1, fp) != 1)
+ pr_warning("WARNING: failed to write to file '%s': %s, skip
object dumping\n",
+ obj_path, strerror(errno));
+ fclose(fp);
+out:
+ free(obj_path);
+}
+
int llvm__compile_bpf(const char *path, void **p_obj_buf,
size_t *p_obj_buf_sz)
{
@@ -411,6 +449,10 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
free(kbuild_dir);
free(kbuild_include_opts);
+
+ if (llvm_param.dump_obj)
+ dump_obj(path, obj_buf, obj_buf_sz);
+
if (!p_obj_buf)
free(obj_buf);
else
diff --git a/tools/perf/util/llvm-utils.h b/tools/perf/util/llvm-utils.h
index 23b9a74..9f501ce 100644
--- a/tools/perf/util/llvm-utils.h
+++ b/tools/perf/util/llvm-utils.h
@@ -30,6 +30,11 @@ struct llvm_param {
*/
const char *kbuild_opts;
/*
+ * Default is false. If set to true, write compiling result
+ * to object file.
+ */
+ bool dump_obj;
+ /*
* Default is false. If one of the above fields is set by user
* explicitly then user_set_llvm is set to true. This is used
* for perf test. If user doesn't set anything in .perfconfig
