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-rw-r--r--tools/bpf/bpftool/Documentation/bpftool-gen.rst58
-rw-r--r--tools/bpf/bpftool/gen.c246
-rw-r--r--tools/bpf/resolve_btfids/main.c70
3 files changed, 350 insertions, 24 deletions
diff --git a/tools/bpf/bpftool/Documentation/bpftool-gen.rst b/tools/bpf/bpftool/Documentation/bpftool-gen.rst
index 5006e724d1bc..5e60825818dd 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-gen.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-gen.rst
@@ -257,18 +257,48 @@ EXAMPLES
return 0;
}
-This is example BPF application with two BPF programs and a mix of BPF maps
-and global variables. Source code is split across two source code files.
+**$ cat example3.bpf.c**
+
+::
+
+ #include <linux/ptrace.h>
+ #include <linux/bpf.h>
+ #include <bpf/bpf_helpers.h>
+ /* This header file is provided by the bpf_testmod module. */
+ #include "bpf_testmod.h"
+
+ int test_2_result = 0;
+
+ /* bpf_Testmod.ko calls this function, passing a "4"
+ * and testmod_map->data.
+ */
+ SEC("struct_ops/test_2")
+ void BPF_PROG(test_2, int a, int b)
+ {
+ test_2_result = a + b;
+ }
+
+ SEC(".struct_ops")
+ struct bpf_testmod_ops testmod_map = {
+ .test_2 = (void *)test_2,
+ .data = 0x1,
+ };
+
+This is example BPF application with three BPF programs and a mix of BPF
+maps and global variables. Source code is split across three source code
+files.
**$ clang --target=bpf -g example1.bpf.c -o example1.bpf.o**
**$ clang --target=bpf -g example2.bpf.c -o example2.bpf.o**
-**$ bpftool gen object example.bpf.o example1.bpf.o example2.bpf.o**
+**$ clang --target=bpf -g example3.bpf.c -o example3.bpf.o**
+
+**$ bpftool gen object example.bpf.o example1.bpf.o example2.bpf.o example3.bpf.o**
-This set of commands compiles *example1.bpf.c* and *example2.bpf.c*
-individually and then statically links respective object files into the final
-BPF ELF object file *example.bpf.o*.
+This set of commands compiles *example1.bpf.c*, *example2.bpf.c* and
+*example3.bpf.c* individually and then statically links respective object
+files into the final BPF ELF object file *example.bpf.o*.
**$ bpftool gen skeleton example.bpf.o name example | tee example.skel.h**
@@ -291,7 +321,15 @@ BPF ELF object file *example.bpf.o*.
struct bpf_map *data;
struct bpf_map *bss;
struct bpf_map *my_map;
+ struct bpf_map *testmod_map;
} maps;
+ struct {
+ struct example__testmod_map__bpf_testmod_ops {
+ const struct bpf_program *test_1;
+ const struct bpf_program *test_2;
+ int data;
+ } *testmod_map;
+ } struct_ops;
struct {
struct bpf_program *handle_sys_enter;
struct bpf_program *handle_sys_exit;
@@ -304,6 +342,7 @@ BPF ELF object file *example.bpf.o*.
struct {
int x;
} data;
+ int test_2_result;
} *bss;
struct example__data {
_Bool global_flag;
@@ -342,10 +381,16 @@ BPF ELF object file *example.bpf.o*.
skel->rodata->param1 = 128;
+ /* Change the value through the pointer of shadow type */
+ skel->struct_ops.testmod_map->data = 13;
+
err = example__load(skel);
if (err)
goto cleanup;
+ /* The result of the function test_2() */
+ printf("test_2_result: %d\n", skel->bss->test_2_result);
+
err = example__attach(skel);
if (err)
goto cleanup;
@@ -372,6 +417,7 @@ BPF ELF object file *example.bpf.o*.
::
+ test_2_result: 17
my_map name: my_map
sys_enter prog FD: 8
my_static_var: 7
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index ee3ce2b8000d..1f579eacd9d4 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -7,6 +7,7 @@
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
+#include <libgen.h>
#include <linux/err.h>
#include <stdbool.h>
#include <stdio.h>
@@ -54,11 +55,27 @@ static bool str_has_suffix(const char *str, const char *suffix)
return true;
}
+static const struct btf_type *
+resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
+{
+ const struct btf_type *t;
+
+ t = skip_mods_and_typedefs(btf, id, NULL);
+ if (!btf_is_ptr(t))
+ return NULL;
+
+ t = skip_mods_and_typedefs(btf, t->type, res_id);
+
+ return btf_is_func_proto(t) ? t : NULL;
+}
+
static void get_obj_name(char *name, const char *file)
{
- /* Using basename() GNU version which doesn't modify arg. */
- strncpy(name, basename(file), MAX_OBJ_NAME_LEN - 1);
- name[MAX_OBJ_NAME_LEN - 1] = '\0';
+ char file_copy[PATH_MAX];
+
+ /* Using basename() POSIX version to be more portable. */
+ strncpy(file_copy, file, PATH_MAX - 1)[PATH_MAX - 1] = '\0';
+ strncpy(name, basename(file_copy), MAX_OBJ_NAME_LEN - 1)[MAX_OBJ_NAME_LEN - 1] = '\0';
if (str_has_suffix(name, ".o"))
name[strlen(name) - 2] = '\0';
sanitize_identifier(name);
@@ -906,6 +923,207 @@ codegen_progs_skeleton(struct bpf_object *obj, size_t prog_cnt, bool populate_li
}
}
+static int walk_st_ops_shadow_vars(struct btf *btf, const char *ident,
+ const struct btf_type *map_type, __u32 map_type_id)
+{
+ LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts, .indent_level = 3);
+ const struct btf_type *member_type;
+ __u32 offset, next_offset = 0;
+ const struct btf_member *m;
+ struct btf_dump *d = NULL;
+ const char *member_name;
+ __u32 member_type_id;
+ int i, err = 0, n;
+ int size;
+
+ d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
+ if (!d)
+ return -errno;
+
+ n = btf_vlen(map_type);
+ for (i = 0, m = btf_members(map_type); i < n; i++, m++) {
+ member_type = skip_mods_and_typedefs(btf, m->type, &member_type_id);
+ member_name = btf__name_by_offset(btf, m->name_off);
+
+ offset = m->offset / 8;
+ if (next_offset < offset)
+ printf("\t\t\tchar __padding_%d[%d];\n", i, offset - next_offset);
+
+ switch (btf_kind(member_type)) {
+ case BTF_KIND_INT:
+ case BTF_KIND_FLOAT:
+ case BTF_KIND_ENUM:
+ case BTF_KIND_ENUM64:
+ /* scalar type */
+ printf("\t\t\t");
+ opts.field_name = member_name;
+ err = btf_dump__emit_type_decl(d, member_type_id, &opts);
+ if (err) {
+ p_err("Failed to emit type declaration for %s: %d", member_name, err);
+ goto out;
+ }
+ printf(";\n");
+
+ size = btf__resolve_size(btf, member_type_id);
+ if (size < 0) {
+ p_err("Failed to resolve size of %s: %d\n", member_name, size);
+ err = size;
+ goto out;
+ }
+
+ next_offset = offset + size;
+ break;
+
+ case BTF_KIND_PTR:
+ if (resolve_func_ptr(btf, m->type, NULL)) {
+ /* Function pointer */
+ printf("\t\t\tstruct bpf_program *%s;\n", member_name);
+
+ next_offset = offset + sizeof(void *);
+ break;
+ }
+ /* All pointer types are unsupported except for
+ * function pointers.
+ */
+ fallthrough;
+
+ default:
+ /* Unsupported types
+ *
+ * Types other than scalar types and function
+ * pointers are currently not supported in order to
+ * prevent conflicts in the generated code caused
+ * by multiple definitions. For instance, if the
+ * struct type FOO is used in a struct_ops map,
+ * bpftool has to generate definitions for FOO,
+ * which may result in conflicts if FOO is defined
+ * in different skeleton files.
+ */
+ size = btf__resolve_size(btf, member_type_id);
+ if (size < 0) {
+ p_err("Failed to resolve size of %s: %d\n", member_name, size);
+ err = size;
+ goto out;
+ }
+ printf("\t\t\tchar __unsupported_%d[%d];\n", i, size);
+
+ next_offset = offset + size;
+ break;
+ }
+ }
+
+ /* Cannot fail since it must be a struct type */
+ size = btf__resolve_size(btf, map_type_id);
+ if (next_offset < (__u32)size)
+ printf("\t\t\tchar __padding_end[%d];\n", size - next_offset);
+
+out:
+ btf_dump__free(d);
+
+ return err;
+}
+
+/* Generate the pointer of the shadow type for a struct_ops map.
+ *
+ * This function adds a pointer of the shadow type for a struct_ops map.
+ * The members of a struct_ops map can be exported through a pointer to a
+ * shadow type. The user can access these members through the pointer.
+ *
+ * A shadow type includes not all members, only members of some types.
+ * They are scalar types and function pointers. The function pointers are
+ * translated to the pointer of the struct bpf_program. The scalar types
+ * are translated to the original type without any modifiers.
+ *
+ * Unsupported types will be translated to a char array to occupy the same
+ * space as the original field, being renamed as __unsupported_*. The user
+ * should treat these fields as opaque data.
+ */
+static int gen_st_ops_shadow_type(const char *obj_name, struct btf *btf, const char *ident,
+ const struct bpf_map *map)
+{
+ const struct btf_type *map_type;
+ const char *type_name;
+ __u32 map_type_id;
+ int err;
+
+ map_type_id = bpf_map__btf_value_type_id(map);
+ if (map_type_id == 0)
+ return -EINVAL;
+ map_type = btf__type_by_id(btf, map_type_id);
+ if (!map_type)
+ return -EINVAL;
+
+ type_name = btf__name_by_offset(btf, map_type->name_off);
+
+ printf("\t\tstruct %s__%s__%s {\n", obj_name, ident, type_name);
+
+ err = walk_st_ops_shadow_vars(btf, ident, map_type, map_type_id);
+ if (err)
+ return err;
+
+ printf("\t\t} *%s;\n", ident);
+
+ return 0;
+}
+
+static int gen_st_ops_shadow(const char *obj_name, struct btf *btf, struct bpf_object *obj)
+{
+ int err, st_ops_cnt = 0;
+ struct bpf_map *map;
+ char ident[256];
+
+ if (!btf)
+ return 0;
+
+ /* Generate the pointers to shadow types of
+ * struct_ops maps.
+ */
+ bpf_object__for_each_map(map, obj) {
+ if (bpf_map__type(map) != BPF_MAP_TYPE_STRUCT_OPS)
+ continue;
+ if (!get_map_ident(map, ident, sizeof(ident)))
+ continue;
+
+ if (st_ops_cnt == 0) /* first struct_ops map */
+ printf("\tstruct {\n");
+ st_ops_cnt++;
+
+ err = gen_st_ops_shadow_type(obj_name, btf, ident, map);
+ if (err)
+ return err;
+ }
+
+ if (st_ops_cnt)
+ printf("\t} struct_ops;\n");
+
+ return 0;
+}
+
+/* Generate the code to initialize the pointers of shadow types. */
+static void gen_st_ops_shadow_init(struct btf *btf, struct bpf_object *obj)
+{
+ struct bpf_map *map;
+ char ident[256];
+
+ if (!btf)
+ return;
+
+ /* Initialize the pointers to_ops shadow types of
+ * struct_ops maps.
+ */
+ bpf_object__for_each_map(map, obj) {
+ if (bpf_map__type(map) != BPF_MAP_TYPE_STRUCT_OPS)
+ continue;
+ if (!get_map_ident(map, ident, sizeof(ident)))
+ continue;
+ codegen("\
+ \n\
+ obj->struct_ops.%1$s = bpf_map__initial_value(obj->maps.%1$s, NULL);\n\
+ \n\
+ ", ident);
+ }
+}
+
static int do_skeleton(int argc, char **argv)
{
char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")];
@@ -1049,6 +1267,11 @@ static int do_skeleton(int argc, char **argv)
printf("\t} maps;\n");
}
+ btf = bpf_object__btf(obj);
+ err = gen_st_ops_shadow(obj_name, btf, obj);
+ if (err)
+ goto out;
+
if (prog_cnt) {
printf("\tstruct {\n");
bpf_object__for_each_program(prog, obj) {
@@ -1072,7 +1295,6 @@ static int do_skeleton(int argc, char **argv)
printf("\t} links;\n");
}
- btf = bpf_object__btf(obj);
if (btf) {
err = codegen_datasecs(obj, obj_name);
if (err)
@@ -1130,6 +1352,12 @@ static int do_skeleton(int argc, char **argv)
if (err) \n\
goto err_out; \n\
\n\
+ ", obj_name);
+
+ gen_st_ops_shadow_init(btf, obj);
+
+ codegen("\
+ \n\
return obj; \n\
err_out: \n\
%1$s__destroy(obj); \n\
@@ -1439,6 +1667,10 @@ static int do_subskeleton(int argc, char **argv)
printf("\t} maps;\n");
}
+ err = gen_st_ops_shadow(obj_name, btf, obj);
+ if (err)
+ goto out;
+
if (prog_cnt) {
printf("\tstruct {\n");
bpf_object__for_each_program(prog, obj) {
@@ -1550,6 +1782,12 @@ static int do_subskeleton(int argc, char **argv)
if (err) \n\
goto err; \n\
\n\
+ ");
+
+ gen_st_ops_shadow_init(btf, obj);
+
+ codegen("\
+ \n\
return obj; \n\
err: \n\
%1$s__destroy(obj); \n\
diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
index 27a23196d58e..d9520cb826b3 100644
--- a/tools/bpf/resolve_btfids/main.c
+++ b/tools/bpf/resolve_btfids/main.c
@@ -70,6 +70,7 @@
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
+#include <linux/btf_ids.h>
#include <linux/rbtree.h>
#include <linux/zalloc.h>
#include <linux/err.h>
@@ -78,7 +79,7 @@
#include <subcmd/parse-options.h>
#define BTF_IDS_SECTION ".BTF_ids"
-#define BTF_ID "__BTF_ID__"
+#define BTF_ID_PREFIX "__BTF_ID__"
#define BTF_STRUCT "struct"
#define BTF_UNION "union"
@@ -89,6 +90,14 @@
#define ADDR_CNT 100
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+# define ELFDATANATIVE ELFDATA2LSB
+#elif __BYTE_ORDER == __BIG_ENDIAN
+# define ELFDATANATIVE ELFDATA2MSB
+#else
+# error "Unknown machine endianness!"
+#endif
+
struct btf_id {
struct rb_node rb_node;
char *name;
@@ -116,6 +125,7 @@ struct object {
int idlist_shndx;
size_t strtabidx;
unsigned long idlist_addr;
+ int encoding;
} efile;
struct rb_root sets;
@@ -161,7 +171,7 @@ static int eprintf(int level, int var, const char *fmt, ...)
static bool is_btf_id(const char *name)
{
- return name && !strncmp(name, BTF_ID, sizeof(BTF_ID) - 1);
+ return name && !strncmp(name, BTF_ID_PREFIX, sizeof(BTF_ID_PREFIX) - 1);
}
static struct btf_id *btf_id__find(struct rb_root *root, const char *name)
@@ -319,6 +329,7 @@ static int elf_collect(struct object *obj)
{
Elf_Scn *scn = NULL;
size_t shdrstrndx;
+ GElf_Ehdr ehdr;
int idx = 0;
Elf *elf;
int fd;
@@ -350,6 +361,13 @@ static int elf_collect(struct object *obj)
return -1;
}
+ if (gelf_getehdr(obj->efile.elf, &ehdr) == NULL) {
+ pr_err("FAILED cannot get ELF header: %s\n",
+ elf_errmsg(-1));
+ return -1;
+ }
+ obj->efile.encoding = ehdr.e_ident[EI_DATA];
+
/*
* Scan all the elf sections and look for save data
* from .BTF_ids section and symbols.
@@ -441,7 +459,7 @@ static int symbols_collect(struct object *obj)
* __BTF_ID__TYPE__vfs_truncate__0
* prefix = ^
*/
- prefix = name + sizeof(BTF_ID) - 1;
+ prefix = name + sizeof(BTF_ID_PREFIX) - 1;
/* struct */
if (!strncmp(prefix, BTF_STRUCT, sizeof(BTF_STRUCT) - 1)) {
@@ -649,19 +667,18 @@ static int cmp_id(const void *pa, const void *pb)
static int sets_patch(struct object *obj)
{
Elf_Data *data = obj->efile.idlist;
- int *ptr = data->d_buf;
struct rb_node *next;
next = rb_first(&obj->sets);
while (next) {
- unsigned long addr, idx;
+ struct btf_id_set8 *set8;
+ struct btf_id_set *set;
+ unsigned long addr, off;
struct btf_id *id;
- int *base;
- int cnt;
id = rb_entry(next, struct btf_id, rb_node);
addr = id->addr[0];
- idx = addr - obj->efile.idlist_addr;
+ off = addr - obj->efile.idlist_addr;
/* sets are unique */
if (id->addr_cnt != 1) {
@@ -670,14 +687,39 @@ static int sets_patch(struct object *obj)
return -1;
}
- idx = idx / sizeof(int);
- base = &ptr[idx] + (id->is_set8 ? 2 : 1);
- cnt = ptr[idx];
+ if (id->is_set) {
+ set = data->d_buf + off;
+ qsort(set->ids, set->cnt, sizeof(set->ids[0]), cmp_id);
+ } else {
+ set8 = data->d_buf + off;
+ /*
+ * Make sure id is at the beginning of the pairs
+ * struct, otherwise the below qsort would not work.
+ */
+ BUILD_BUG_ON(set8->pairs != &set8->pairs[0].id);
+ qsort(set8->pairs, set8->cnt, sizeof(set8->pairs[0]), cmp_id);
- pr_debug("sorting addr %5lu: cnt %6d [%s]\n",
- (idx + 1) * sizeof(int), cnt, id->name);
+ /*
+ * When ELF endianness does not match endianness of the
+ * host, libelf will do the translation when updating
+ * the ELF. This, however, corrupts SET8 flags which are
+ * already in the target endianness. So, let's bswap
+ * them to the host endianness and libelf will then
+ * correctly translate everything.
+ */
+ if (obj->efile.encoding != ELFDATANATIVE) {
+ int i;
+
+ set8->flags = bswap_32(set8->flags);
+ for (i = 0; i < set8->cnt; i++) {
+ set8->pairs[i].flags =
+ bswap_32(set8->pairs[i].flags);
+ }
+ }
+ }
- qsort(base, cnt, id->is_set8 ? sizeof(uint64_t) : sizeof(int), cmp_id);
+ pr_debug("sorting addr %5lu: cnt %6d [%s]\n",
+ off, id->is_set ? set->cnt : set8->cnt, id->name);
next = rb_next(next);
}
generated by cgit (git 2.34.1) at 2025-05-30 13:40:37 +0000