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bpftool: Display cookie for kprobe multi link
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Displaying cookies for kprobe multi link, in plain mode:

  # bpftool link
  ...
  1397: kprobe_multi  prog 47532
          kretprobe.multi  func_cnt 3
          addr             cookie           func [module]
          ffffffff82b370c0 3                bpf_fentry_test1
          ffffffff82b39780 1                bpf_fentry_test2
          ffffffff82b397a0 2                bpf_fentry_test3

And in json mode:

  # bpftool link -j | jq
  ...
    {
      "id": 1397,
      "type": "kprobe_multi",
      "prog_id": 47532,
      "retprobe": true,
      "func_cnt": 3,
      "missed": 0,
      "funcs": [
        {
          "addr": 18446744071607382208,
          "func": "bpf_fentry_test1",
          "module": null,
          "cookie": 3
        },
        {
          "addr": 18446744071607392128,
          "func": "bpf_fentry_test2",
          "module": null,
          "cookie": 1
        },
        {
          "addr": 18446744071607392160,
          "func": "bpf_fentry_test3",
          "module": null,
          "cookie": 2
        }
      ]
    }

Cookie is attached to specific address, and because we sort addresses
before printing, we need to sort cookies the same way, hence adding
the struct addr_cookie to keep and sort them together.

Also adding missing dd.sym_count check to show_kprobe_multi_json.

Signed-off-by: Jiri Olsa <[email protected]>
Acked-by: Song Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
  • Loading branch information
@olsajiri @qmonnet
olsajiri authored and qmonnet committed Jan 29, 2024
1 parent 25df69b commit 4263cc0
Showing 1 changed file with 63 additions and 15 deletions.
78 changes: 63 additions & 15 deletions src/link.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -249,33 +249,65 @@ static int get_prog_info(int prog_id, struct bpf_prog_info *info)
return err;
}

static int cmp_u64(const void *A, const void *B)
struct addr_cookie {
__u64 addr;
__u64 cookie;
};

static int cmp_addr_cookie(const void *A, const void *B)
{
const struct addr_cookie *a = A, *b = B;

if (a->addr == b->addr)
return 0;
return a->addr < b->addr ? -1 : 1;
}

static struct addr_cookie *
get_addr_cookie_array(__u64 *addrs, __u64 *cookies, __u32 count)
{
const __u64 *a = A, *b = B;
struct addr_cookie *data;
__u32 i;

return *a - *b;
data = calloc(count, sizeof(data[0]));
if (!data) {
p_err("mem alloc failed");
return NULL;
}
for (i = 0; i < count; i++) {
data[i].addr = addrs[i];
data[i].cookie = cookies[i];
}
qsort(data, count, sizeof(data[0]), cmp_addr_cookie);
return data;
}

static void
show_kprobe_multi_json(struct bpf_link_info *info, json_writer_t *wtr)
{
struct addr_cookie *data;
__u32 i, j = 0;
__u64 *addrs;

jsonw_bool_field(json_wtr, "retprobe",
info->kprobe_multi.flags & BPF_F_KPROBE_MULTI_RETURN);
jsonw_uint_field(json_wtr, "func_cnt", info->kprobe_multi.count);
jsonw_uint_field(json_wtr, "missed", info->kprobe_multi.missed);
jsonw_name(json_wtr, "funcs");
jsonw_start_array(json_wtr);
addrs = u64_to_ptr(info->kprobe_multi.addrs);
qsort(addrs, info->kprobe_multi.count, sizeof(addrs[0]), cmp_u64);
data = get_addr_cookie_array(u64_to_ptr(info->kprobe_multi.addrs),
u64_to_ptr(info->kprobe_multi.cookies),
info->kprobe_multi.count);
if (!data)
return;

/* Load it once for all. */
if (!dd.sym_count)
kernel_syms_load(&dd);
if (!dd.sym_count)
goto error;

for (i = 0; i < dd.sym_count; i++) {
if (dd.sym_mapping[i].address != addrs[j])
if (dd.sym_mapping[i].address != data[j].addr)
continue;
jsonw_start_object(json_wtr);
jsonw_uint_field(json_wtr, "addr", dd.sym_mapping[i].address);
Expand All @@ -287,11 +319,14 @@ show_kprobe_multi_json(struct bpf_link_info *info, json_writer_t *wtr)
} else {
jsonw_string_field(json_wtr, "module", dd.sym_mapping[i].module);
}
jsonw_uint_field(json_wtr, "cookie", data[j].cookie);
jsonw_end_object(json_wtr);
if (j++ == info->kprobe_multi.count)
break;
}
jsonw_end_array(json_wtr);
error:
free(data);
}

static __u64 *u64_to_arr(__u64 val)
Expand Down Expand Up @@ -675,8 +710,8 @@ void netfilter_dump_plain(const struct bpf_link_info *info)

static void show_kprobe_multi_plain(struct bpf_link_info *info)
{
struct addr_cookie *data;
__u32 i, j = 0;
__u64 *addrs;

if (!info->kprobe_multi.count)
return;
Expand All @@ -688,21 +723,24 @@ static void show_kprobe_multi_plain(struct bpf_link_info *info)
printf("func_cnt %u ", info->kprobe_multi.count);
if (info->kprobe_multi.missed)
printf("missed %llu ", info->kprobe_multi.missed);
addrs = (__u64 *)u64_to_ptr(info->kprobe_multi.addrs);
qsort(addrs, info->kprobe_multi.count, sizeof(__u64), cmp_u64);
data = get_addr_cookie_array(u64_to_ptr(info->kprobe_multi.addrs),
u64_to_ptr(info->kprobe_multi.cookies),
info->kprobe_multi.count);
if (!data)
return;

/* Load it once for all. */
if (!dd.sym_count)
kernel_syms_load(&dd);
if (!dd.sym_count)
return;
goto error;

printf("\n\t%-16s %s", "addr", "func [module]");
printf("\n\t%-16s %-16s %s", "addr", "cookie", "func [module]");
for (i = 0; i < dd.sym_count; i++) {
if (dd.sym_mapping[i].address != addrs[j])
if (dd.sym_mapping[i].address != data[j].addr)
continue;
printf("\n\t%016lx %s",
dd.sym_mapping[i].address, dd.sym_mapping[i].name);
printf("\n\t%016lx %-16llx %s",
dd.sym_mapping[i].address, data[j].cookie, dd.sym_mapping[i].name);
if (dd.sym_mapping[i].module[0] != '\0')
printf(" [%s] ", dd.sym_mapping[i].module);
else
Expand All @@ -711,6 +749,8 @@ static void show_kprobe_multi_plain(struct bpf_link_info *info)
if (j++ == info->kprobe_multi.count)
break;
}
error:
free(data);
}

static void show_uprobe_multi_plain(struct bpf_link_info *info)
Expand Down Expand Up @@ -966,6 +1006,14 @@ static int do_show_link(int fd)
return -ENOMEM;
}
info.kprobe_multi.addrs = ptr_to_u64(addrs);
cookies = calloc(count, sizeof(__u64));
if (!cookies) {
p_err("mem alloc failed");
free(addrs);
close(fd);
return -ENOMEM;
}
info.kprobe_multi.cookies = ptr_to_u64(cookies);
goto again;
}
}
Expand Down

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