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libxdp: Convert xdp-dispatcher to use strict section names
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Use SEC("xdp") as recommended by new strict section naming rules in
upstream libbpf, and backport the internal __xdp_program__find_file()
function from the master branch to find BPF program in object by program
name instead of section name.

This is a backport of commit:

d165118 ("libxdp: Convert xdp-dispatcher to use strict section name")

from the master branch, with the internal functions from commit:

239e64e ("libxdp: Introduce OPTS based xdp_program__create")

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
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@tohojo
tohojo committed Dec 12, 2022
1 parent b1fd2e5 commit 5dfe342
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Showing 2 changed files with 39 additions and 17 deletions.
52 changes: 37 additions & 15 deletions lib/libxdp/libxdp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,7 @@ static const char *xdp_action_names[] = {

static struct xdp_program *xdp_program__create_from_obj(struct bpf_object *obj,
const char *section_name,
const char *prog_name,
bool external);

#ifdef LIBXDP_STATIC
Expand All @@ -119,6 +120,7 @@ static struct xdp_embedded_obj embedded_objs[] = {
};
static struct xdp_program *xdp_program__find_embedded(const char *filename,
const char *section_name,
const char *prog_name,
struct bpf_object_open_opts *opts)
{
DECLARE_LIBBPF_OPTS(bpf_object_open_opts, default_opts,
Expand Down Expand Up @@ -149,14 +151,15 @@ static struct xdp_program *xdp_program__find_embedded(const char *filename,
err = libbpf_get_error(obj);
if (err)
return ERR_PTR(err);
return xdp_program__create_from_obj(obj, section_name, false);
return xdp_program__create_from_obj(obj, section_name, prog_name, false);
}

return NULL;
}
#else
static inline struct xdp_program *xdp_program__find_embedded(__unused const char *filename,
__unused const char *section_name,
__unused const char *prog_name,
__unused struct bpf_object_open_opts *opts)
{
return NULL;
Expand Down Expand Up @@ -954,17 +957,20 @@ void xdp_program__close(struct xdp_program *xdp_prog)

static struct xdp_program *xdp_program__create_from_obj(struct bpf_object *obj,
const char *section_name,
const char *prog_name,
bool external)
{
struct xdp_program *xdp_prog;
struct bpf_program *bpf_prog;
int err;

if (!obj)
if (!obj || (section_name && prog_name))
return ERR_PTR(-EINVAL);

if (section_name)
bpf_prog = bpf_program_by_section_name(obj, section_name);
else if (prog_name)
bpf_prog = bpf_object__find_program_by_name(obj, prog_name);
else
bpf_prog = bpf_object__next_program(obj, NULL);

Expand Down Expand Up @@ -1002,7 +1008,7 @@ static struct xdp_program *xdp_program__create_from_obj(struct bpf_object *obj,
struct xdp_program *xdp_program__from_bpf_obj(struct bpf_object *obj,
const char *section_name)
{
return xdp_program__create_from_obj(obj, section_name, true);
return xdp_program__create_from_obj(obj, section_name, NULL, true);
}

static struct bpf_object *open_bpf_obj(const char *filename,
Expand All @@ -1025,9 +1031,10 @@ static struct bpf_object *open_bpf_obj(const char *filename,
return obj;
}

struct xdp_program *xdp_program__open_file(const char *filename,
const char *section_name,
struct bpf_object_open_opts *opts)
static struct xdp_program *__xdp_program__open_file(const char *filename,
const char *section_name,
const char *prog_name,
struct bpf_object_open_opts *opts)
{
struct xdp_program *xdp_prog;
struct bpf_object *obj;
Expand All @@ -1042,13 +1049,20 @@ struct xdp_program *xdp_program__open_file(const char *filename,
return ERR_PTR(err);
}

xdp_prog = xdp_program__create_from_obj(obj, section_name, false);
xdp_prog = xdp_program__create_from_obj(obj, section_name, prog_name, false);
if (IS_ERR(xdp_prog))
bpf_object__close(obj);

return xdp_prog;
}

struct xdp_program *xdp_program__open_file(const char *filename,
const char *section_name,
struct bpf_object_open_opts *opts)
{
return __xdp_program__open_file(filename, section_name, NULL, opts);
}

static bool try_bpf_file(char *buf, size_t buf_size, char *path,
const char *progname)
{
Expand Down Expand Up @@ -1088,15 +1102,16 @@ static int find_bpf_file(char *buf, size_t buf_size, const char *progname)
return -ENOENT;
}

struct xdp_program *xdp_program__find_file(const char *filename,
const char *section_name,
struct bpf_object_open_opts *opts)
static struct xdp_program *__xdp_program__find_file(const char *filename,
const char *section_name,
const char *prog_name,
struct bpf_object_open_opts *opts)
{
struct xdp_program *prog;
char buf[PATH_MAX];
int err;

prog = xdp_program__find_embedded(filename, section_name, opts);
prog = xdp_program__find_embedded(filename, section_name, prog_name, opts);
if (prog)
return prog;

Expand All @@ -1105,7 +1120,14 @@ struct xdp_program *xdp_program__find_file(const char *filename,
return ERR_PTR(err);

pr_debug("Loading XDP program from '%s' section '%s'\n", buf, section_name);
return xdp_program__open_file(buf, section_name, opts);
return __xdp_program__open_file(buf, section_name, prog_name, opts);
}

struct xdp_program *xdp_program__find_file(const char *filename,
const char *section_name,
struct bpf_object_open_opts *opts)
{
return __xdp_program__find_file(filename, section_name, NULL, opts);
}

static int xdp_program__fill_from_fd(struct xdp_program *xdp_prog, int fd)
Expand Down Expand Up @@ -2101,7 +2123,7 @@ static int xdp_multiprog__check_compat(struct xdp_multiprog *mp)
return 0;

pr_debug("Checking dispatcher compatibility\n");
test_prog = xdp_program__find_file("xdp-dispatcher.o", "xdp/pass", NULL);
test_prog = __xdp_program__find_file("xdp-dispatcher.o", NULL, "xdp_pass", NULL);
if (IS_ERR(test_prog)) {
err = PTR_ERR(test_prog);
pr_warn("Couldn't open BPF file xdp-dispatcher.o\n");
Expand Down Expand Up @@ -2449,8 +2471,8 @@ static struct xdp_multiprog *xdp_multiprog__generate(struct xdp_program **progs,
if (num_new_progs > 1)
qsort(new_progs, num_new_progs, sizeof(*new_progs), cmp_xdp_programs);

dispatcher = xdp_program__find_file("xdp-dispatcher.o",
"xdp/dispatcher", NULL);
dispatcher = __xdp_program__find_file("xdp-dispatcher.o", NULL,
"xdp_dispatcher", NULL);
if (IS_ERR(dispatcher)) {
err = PTR_ERR(dispatcher);
pr_warn("Couldn't open BPF file 'xdp-dispatcher.o'\n");
Expand Down
4 changes: 2 additions & 2 deletions lib/libxdp/xdp-dispatcher.c.in
View file
Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,7 @@ int compat_test(struct xdp_md *ctx) {
}


SEC("xdp/dispatcher")
SEC("xdp")
int xdp_dispatcher(struct xdp_md *ctx)
{
__u8 num_progs_enabled = conf.num_progs_enabled;
Expand All @@ -73,7 +73,7 @@ out:
return XDP_PASS;
}

SEC("xdp/pass")
SEC("xdp")
int xdp_pass(struct xdp_md *ctx)
{
return XDP_PASS;
Expand Down

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