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bpf: libbpf: Add btf_line_info support to libbpf

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This patch adds bpf_line_info support to libbpf:
1) Parsing the line_info sec from ".BTF.ext"
2) Relocating the line_info.  If the main prog *_info relocation
   fails, it will ignore the remaining subprog line_info and continue.
   If the subprog *_info relocation fails, it will bail out.
3) BPF_PROG_LOAD a prog with line_info

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Martin KaFai Lau 2018-12-07 16:42:31 -08:00 • committed by Alexei Starovoitov
parent f0187f0b17
commit 3d65014146
5 changed files with 238 additions and 88 deletions
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82
tools/lib/bpf/bpf.c
View file

@ -173,11 +173,36 @@ int bpf_create_map_in_map(enum bpf_map_type map_type, const char *name,
-1);
}
static void *
alloc_zero_tailing_info(const void *orecord, __u32 cnt,
__u32 actual_rec_size, __u32 expected_rec_size)
{
__u64 info_len = actual_rec_size * cnt;
void *info, *nrecord;
int i;
info = malloc(info_len);
if (!info)
return NULL;
/* zero out bytes kernel does not understand */
nrecord = info;
for (i = 0; i < cnt; i++) {
memcpy(nrecord, orecord, expected_rec_size);
memset(nrecord + expected_rec_size, 0,
actual_rec_size - expected_rec_size);
orecord += actual_rec_size;
nrecord += actual_rec_size;
}
return info;
}
int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
char *log_buf, size_t log_buf_sz)
{
void *finfo = NULL, *linfo = NULL;
union bpf_attr attr;
void *finfo = NULL;
__u32 name_len;
int fd;
@ -201,6 +226,9 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
attr.func_info_rec_size = load_attr->func_info_rec_size;
attr.func_info_cnt = load_attr->func_info_cnt;
attr.func_info = ptr_to_u64(load_attr->func_info);
attr.line_info_rec_size = load_attr->line_info_rec_size;
attr.line_info_cnt = load_attr->line_info_cnt;
attr.line_info = ptr_to_u64(load_attr->line_info);
memcpy(attr.prog_name, load_attr->name,
min(name_len, BPF_OBJ_NAME_LEN - 1));
@ -212,36 +240,35 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
* to give user space a hint how to deal with loading failure.
* Check to see whether we can make some changes and load again.
*/
if (errno == E2BIG && attr.func_info_cnt &&
attr.func_info_rec_size < load_attr->func_info_rec_size) {
__u32 actual_rec_size = load_attr->func_info_rec_size;
__u32 expected_rec_size = attr.func_info_rec_size;
__u32 finfo_cnt = load_attr->func_info_cnt;
__u64 finfo_len = actual_rec_size * finfo_cnt;
const void *orecord;
void *nrecord;
int i;
while (errno == E2BIG && (!finfo || !linfo)) {
if (!finfo && attr.func_info_cnt &&
attr.func_info_rec_size < load_attr->func_info_rec_size) {
/* try with corrected func info records */
finfo = alloc_zero_tailing_info(load_attr->func_info,
load_attr->func_info_cnt,
load_attr->func_info_rec_size,
attr.func_info_rec_size);
if (!finfo)
goto done;
finfo = malloc(finfo_len);
if (!finfo)
/* further try with log buffer won't help */
return fd;
attr.func_info = ptr_to_u64(finfo);
attr.func_info_rec_size = load_attr->func_info_rec_size;
} else if (!linfo && attr.line_info_cnt &&
attr.line_info_rec_size <
load_attr->line_info_rec_size) {
linfo = alloc_zero_tailing_info(load_attr->line_info,
load_attr->line_info_cnt,
load_attr->line_info_rec_size,
attr.line_info_rec_size);
if (!linfo)
goto done;
/* zero out bytes kernel does not understand */
orecord = load_attr->func_info;
nrecord = finfo;
for (i = 0; i < load_attr->func_info_cnt; i++) {
memcpy(nrecord, orecord, expected_rec_size);
memset(nrecord + expected_rec_size, 0,
actual_rec_size - expected_rec_size);
orecord += actual_rec_size;
nrecord += actual_rec_size;
attr.line_info = ptr_to_u64(linfo);
attr.line_info_rec_size = load_attr->line_info_rec_size;
} else {
break;
}
/* try with corrected func info records */
attr.func_info = ptr_to_u64(finfo);
attr.func_info_rec_size = load_attr->func_info_rec_size;
fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
if (fd >= 0)
@ -259,6 +286,7 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
done:
free(finfo);
free(linfo);
return fd;
}