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-rw-r--r--include/uapi/linux/btf.h3
-rw-r--r--tools/include/uapi/linux/btf.h7
-rw-r--r--tools/lib/bpf/Makefile15
-rw-r--r--tools/lib/bpf/bpf_helpers.h9
-rw-r--r--tools/lib/bpf/btf.c9
-rw-r--r--tools/lib/bpf/libbpf.c738
-rw-r--r--tools/lib/bpf/libbpf.h12
-rw-r--r--tools/testing/selftests/bpf/Makefile2
8 files changed, 729 insertions, 66 deletions
diff --git a/include/uapi/linux/btf.h b/include/uapi/linux/btf.h
index c02dec97e1ce..1a2898c482ee 100644
--- a/include/uapi/linux/btf.h
+++ b/include/uapi/linux/btf.h
@@ -142,7 +142,8 @@ struct btf_param {
enum {
BTF_VAR_STATIC = 0,
- BTF_VAR_GLOBAL_ALLOCATED,
+ BTF_VAR_GLOBAL_ALLOCATED = 1,
+ BTF_VAR_GLOBAL_EXTERN = 2,
};
/* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
diff --git a/tools/include/uapi/linux/btf.h b/tools/include/uapi/linux/btf.h
index 63ae4a39e58b..1a2898c482ee 100644
--- a/tools/include/uapi/linux/btf.h
+++ b/tools/include/uapi/linux/btf.h
@@ -22,9 +22,9 @@ struct btf_header {
};
/* Max # of type identifier */
-#define BTF_MAX_TYPE 0x0000ffff
+#define BTF_MAX_TYPE 0x000fffff
/* Max offset into the string section */
-#define BTF_MAX_NAME_OFFSET 0x0000ffff
+#define BTF_MAX_NAME_OFFSET 0x00ffffff
/* Max # of struct/union/enum members or func args */
#define BTF_MAX_VLEN 0xffff
@@ -142,7 +142,8 @@ struct btf_param {
enum {
BTF_VAR_STATIC = 0,
- BTF_VAR_GLOBAL_ALLOCATED,
+ BTF_VAR_GLOBAL_ALLOCATED = 1,
+ BTF_VAR_GLOBAL_EXTERN = 2,
};
/* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 23ae06c43d08..a3718cb275f2 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -56,8 +56,8 @@ ifndef VERBOSE
endif
FEATURE_USER = .libbpf
-FEATURE_TESTS = libelf libelf-mmap bpf reallocarray
-FEATURE_DISPLAY = libelf bpf
+FEATURE_TESTS = libelf libelf-mmap zlib bpf reallocarray
+FEATURE_DISPLAY = libelf zlib bpf
INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi
FEATURE_CHECK_CFLAGS-bpf = $(INCLUDES)
@@ -160,7 +160,7 @@ all: fixdep
all_cmd: $(CMD_TARGETS) check
-$(BPF_IN_SHARED): force elfdep bpfdep bpf_helper_defs.h
+$(BPF_IN_SHARED): force elfdep zdep bpfdep bpf_helper_defs.h
@(test -f ../../include/uapi/linux/bpf.h -a -f ../../../include/uapi/linux/bpf.h && ( \
(diff -B ../../include/uapi/linux/bpf.h ../../../include/uapi/linux/bpf.h >/dev/null) || \
echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/bpf.h' differs from latest version at 'include/uapi/linux/bpf.h'" >&2 )) || true
@@ -178,7 +178,7 @@ $(BPF_IN_SHARED): force elfdep bpfdep bpf_helper_defs.h
echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/if_xdp.h' differs from latest version at 'include/uapi/linux/if_xdp.h'" >&2 )) || true
$(Q)$(MAKE) $(build)=libbpf OUTPUT=$(SHARED_OBJDIR) CFLAGS="$(CFLAGS) $(SHLIB_FLAGS)"
-$(BPF_IN_STATIC): force elfdep bpfdep bpf_helper_defs.h
+$(BPF_IN_STATIC): force elfdep zdep bpfdep bpf_helper_defs.h
$(Q)$(MAKE) $(build)=libbpf OUTPUT=$(STATIC_OBJDIR)
bpf_helper_defs.h: $(srctree)/tools/include/uapi/linux/bpf.h
@@ -190,7 +190,7 @@ $(OUTPUT)libbpf.so: $(OUTPUT)libbpf.so.$(LIBBPF_VERSION)
$(OUTPUT)libbpf.so.$(LIBBPF_VERSION): $(BPF_IN_SHARED)
$(QUIET_LINK)$(CC) $(LDFLAGS) \
--shared -Wl,-soname,libbpf.so.$(LIBBPF_MAJOR_VERSION) \
- -Wl,--version-script=$(VERSION_SCRIPT) $^ -lelf -o $@
+ -Wl,--version-script=$(VERSION_SCRIPT) $^ -lelf -lz -o $@
@ln -sf $(@F) $(OUTPUT)libbpf.so
@ln -sf $(@F) $(OUTPUT)libbpf.so.$(LIBBPF_MAJOR_VERSION)
@@ -279,12 +279,15 @@ clean:
-PHONY += force elfdep bpfdep cscope tags
+PHONY += force elfdep zdep bpfdep cscope tags
force:
elfdep:
@if [ "$(feature-libelf)" != "1" ]; then echo "No libelf found"; exit 1 ; fi
+zdep:
+ @if [ "$(feature-zlib)" != "1" ]; then echo "No zlib found"; exit 1 ; fi
+
bpfdep:
@if [ "$(feature-bpf)" != "1" ]; then echo "BPF API too old"; exit 1 ; fi
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index 0c7d28292898..aa46700075e1 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -25,6 +25,9 @@
#ifndef __always_inline
#define __always_inline __attribute__((always_inline))
#endif
+#ifndef __weak
+#define __weak __attribute__((weak))
+#endif
/*
* Helper structure used by eBPF C program
@@ -44,4 +47,10 @@ enum libbpf_pin_type {
LIBBPF_PIN_BY_NAME,
};
+enum libbpf_tristate {
+ TRI_NO = 0,
+ TRI_YES = 1,
+ TRI_MODULE = 2,
+};
+
#endif
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 84fe82f27bef..520021939d81 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -578,6 +578,12 @@ static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
return -ENOENT;
}
+ /* .extern datasec size and var offsets were set correctly during
+ * extern collection step, so just skip straight to sorting variables
+ */
+ if (t->size)
+ goto sort_vars;
+
ret = bpf_object__section_size(obj, name, &size);
if (ret || !size || (t->size && t->size != size)) {
pr_debug("Invalid size for section %s: %u bytes\n", name, size);
@@ -614,7 +620,8 @@ static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
vsi->offset = off;
}
- qsort(t + 1, vars, sizeof(*vsi), compare_vsi_off);
+sort_vars:
+ qsort(btf_var_secinfos(t), vars, sizeof(*vsi), compare_vsi_off);
return 0;
}
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index f6c135869701..26144706ba0b 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -44,6 +44,7 @@
#include <tools/libc_compat.h>
#include <libelf.h>
#include <gelf.h>
+#include <zlib.h>
#include "libbpf.h"
#include "bpf.h"
@@ -139,6 +140,20 @@ struct bpf_capabilities {
__u32 array_mmap:1;
};
+enum reloc_type {
+ RELO_LD64,
+ RELO_CALL,
+ RELO_DATA,
+ RELO_EXTERN,
+};
+
+struct reloc_desc {
+ enum reloc_type type;
+ int insn_idx;
+ int map_idx;
+ int sym_off;
+};
+
/*
* bpf_prog should be a better name but it has been used in
* linux/filter.h.
@@ -157,16 +172,7 @@ struct bpf_program {
size_t insns_cnt, main_prog_cnt;
enum bpf_prog_type type;
- struct reloc_desc {
- enum {
- RELO_LD64,
- RELO_CALL,
- RELO_DATA,
- } type;
- int insn_idx;
- int map_idx;
- int sym_off;
- } *reloc_desc;
+ struct reloc_desc *reloc_desc;
int nr_reloc;
int log_level;
@@ -198,18 +204,21 @@ struct bpf_program {
#define DATA_SEC ".data"
#define BSS_SEC ".bss"
#define RODATA_SEC ".rodata"
+#define EXTERN_SEC ".extern"
enum libbpf_map_type {
LIBBPF_MAP_UNSPEC,
LIBBPF_MAP_DATA,
LIBBPF_MAP_BSS,
LIBBPF_MAP_RODATA,
+ LIBBPF_MAP_EXTERN,
};
static const char * const libbpf_type_to_btf_name[] = {
[LIBBPF_MAP_DATA] = DATA_SEC,
[LIBBPF_MAP_BSS] = BSS_SEC,
[LIBBPF_MAP_RODATA] = RODATA_SEC,
+ [LIBBPF_MAP_EXTERN] = EXTERN_SEC,
};
struct bpf_map {
@@ -231,6 +240,28 @@ struct bpf_map {
bool reused;
};
+enum extern_type {
+ EXT_UNKNOWN,
+ EXT_CHAR,
+ EXT_BOOL,
+ EXT_INT,
+ EXT_TRISTATE,
+ EXT_CHAR_ARR,
+};
+
+struct extern_desc {
+ const char *name;
+ int sym_idx;
+ int btf_id;
+ enum extern_type type;
+ int sz;
+ int align;
+ int data_off;
+ bool is_signed;
+ bool is_weak;
+ bool is_set;
+};
+
static LIST_HEAD(bpf_objects_list);
struct bpf_object {
@@ -244,6 +275,11 @@ struct bpf_object {
size_t nr_maps;
size_t maps_cap;
+ char *kconfig_path;
+ struct extern_desc *externs;
+ int nr_extern;
+ int extern_map_idx;
+
bool loaded;
bool has_pseudo_calls;
bool relaxed_core_relocs;
@@ -271,6 +307,7 @@ struct bpf_object {
int maps_shndx;
int btf_maps_shndx;
int text_shndx;
+ int symbols_shndx;
int data_shndx;
int rodata_shndx;
int bss_shndx;
@@ -542,6 +579,7 @@ static struct bpf_object *bpf_object__new(const char *path,
obj->efile.data_shndx = -1;
obj->efile.rodata_shndx = -1;
obj->efile.bss_shndx = -1;
+ obj->extern_map_idx = -1;
obj->kern_version = get_kernel_version();
obj->loaded = false;
@@ -866,7 +904,8 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
def->key_size = sizeof(int);
def->value_size = data_sz;
def->max_entries = 1;
- def->map_flags = type == LIBBPF_MAP_RODATA ? BPF_F_RDONLY_PROG : 0;
+ def->map_flags = type == LIBBPF_MAP_RODATA || type == LIBBPF_MAP_EXTERN
+ ? BPF_F_RDONLY_PROG : 0;
def->map_flags |= BPF_F_MMAPABLE;
pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %x.\n",
@@ -883,7 +922,7 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
return err;
}
- if (type != LIBBPF_MAP_BSS)
+ if (data)
memcpy(map->mmaped, data, data_sz);
pr_debug("map %td is \"%s\"\n", map - obj->maps, map->name);
@@ -924,6 +963,271 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj)
return 0;
}
+
+static struct extern_desc *find_extern_by_name(const struct bpf_object *obj,
+ const void *name)
+{
+ int i;
+
+ for (i = 0; i < obj->nr_extern; i++) {
+ if (strcmp(obj->externs[i].name, name) == 0)
+ return &obj->externs[i];
+ }
+ return NULL;
+}
+
+static int set_ext_value_tri(struct extern_desc *ext, void *ext_val,
+ char value)
+{
+ switch (ext->type) {
+ case EXT_BOOL:
+ if (value == 'm') {
+ pr_warn("extern %s=%c should be tristate or char\n",
+ ext->name, value);
+ return -EINVAL;
+ }
+ *(bool *)ext_val = value == 'y' ? true : false;
+ break;
+ case EXT_TRISTATE:
+ if (value == 'y')
+ *(enum libbpf_tristate *)ext_val = TRI_YES;
+ else if (value == 'm')
+ *(enum libbpf_tristate *)ext_val = TRI_MODULE;
+ else /* value == 'n' */
+ *(enum libbpf_tristate *)ext_val = TRI_NO;
+ break;
+ case EXT_CHAR:
+ *(char *)ext_val = value;
+ break;
+ case EXT_UNKNOWN:
+ case EXT_INT:
+ case EXT_CHAR_ARR:
+ default:
+ pr_warn("extern %s=%c should be bool, tristate, or char\n",
+ ext->name, value);
+ return -EINVAL;
+ }
+ ext->is_set = true;
+ return 0;
+}
+
+static int set_ext_value_str(struct extern_desc *ext, char *ext_val,
+ const char *value)
+{
+ size_t len;
+
+ if (ext->type != EXT_CHAR_ARR) {
+ pr_warn("extern %s=%s should char array\n", ext->name, value);
+ return -EINVAL;
+ }
+
+ len = strlen(value);
+ if (value[len - 1] != '"') {
+ pr_warn("extern '%s': invalid string config '%s'\n",
+ ext->name, value);
+ return -EINVAL;
+ }
+
+ /* strip quotes */
+ len -= 2;
+ if (len >= ext->sz) {
+ pr_warn("extern '%s': long string config %s of (%zu bytes) truncated to %d bytes\n",
+ ext->name, value, len, ext->sz - 1);
+ len = ext->sz - 1;
+ }
+ memcpy(ext_val, value + 1, len);
+ ext_val[len] = '\0';
+ ext->is_set = true;
+ return 0;
+}
+
+static int parse_u64(const char *value, __u64 *res)
+{
+ char *value_end;
+ int err;
+
+ errno = 0;
+ *res = strtoull(value, &value_end, 0);
+ if (errno) {
+ err = -errno;
+ pr_warn("failed to parse '%s' as integer: %d\n", value, err);
+ return err;
+ }
+ if (*value_end) {
+ pr_warn("failed to parse '%s' as integer completely\n", value);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static bool is_ext_value_in_range(const struct extern_desc *ext, __u64 v)
+{
+ int bit_sz = ext->sz * 8;
+
+ if (ext->sz == 8)
+ return true;
+
+ /* Validate that value stored in u64 fits in integer of `ext->sz`
+ * bytes size without any loss of information. If the target integer
+ * is signed, we rely on the following limits of integer type of
+ * Y bits and subsequent transformation:
+ *
+ * -2^(Y-1) <= X <= 2^(Y-1) - 1
+ * 0 <= X + 2^(Y-1) <= 2^Y - 1
+ * 0 <= X + 2^(Y-1) < 2^Y
+ *
+ * For unsigned target integer, check that all the (64 - Y) bits are
+ * zero.
+ */
+ if (ext->is_signed)
+ return v + (1ULL << (bit_sz - 1)) < (1ULL << bit_sz);
+ else
+ return (v >> bit_sz) == 0;
+}
+
+static int set_ext_value_num(struct extern_desc *ext, void *ext_val,
+ __u64 value)
+{
+ if (ext->type != EXT_INT && ext->type != EXT_CHAR) {
+ pr_warn("extern %s=%llu should be integer\n",
+ ext->name, value);
+ return -EINVAL;
+ }
+ if (!is_ext_value_in_range(ext, value)) {
+ pr_warn("extern %s=%llu value doesn't fit in %d bytes\n",
+ ext->name, value, ext->sz);
+ return -ERANGE;
+ }
+ switch (ext->sz) {
+ case 1: *(__u8 *)ext_val = value; break;
+ case 2: *(__u16 *)ext_val = value; break;
+ case 4: *(__u32 *)ext_val = value; break;
+ case 8: *(__u64 *)ext_val = value; break;
+ default:
+ return -EINVAL;
+ }
+ ext->is_set = true;
+ return 0;
+}
+
+static int bpf_object__read_kernel_config(struct bpf_object *obj,
+ const char *config_path,
+ void *data)
+{
+ char buf[PATH_MAX], *sep, *value;
+ struct extern_desc *ext;
+ int len, err = 0;
+ void *ext_val;
+ __u64 num;
+ gzFile file;
+
+ if (config_path) {
+ file = gzopen(config_path, "r");
+ } else {
+ struct utsname uts;
+
+ uname(&uts);
+ len = snprintf(buf, PATH_MAX, "/boot/config-%s", uts.release);
+ if (len < 0)
+ return -EINVAL;
+ else if (len >= PATH_MAX)
+ return -ENAMETOOLONG;
+ /* gzopen also accepts uncompressed files. */
+ file = gzopen(buf, "r");
+ if (!file)
+ file = gzopen("/proc/config.gz", "r");
+ }
+ if (!file) {
+ pr_warn("failed to read kernel config at '%s'\n", config_path);
+ return -ENOENT;
+ }
+
+ while (gzgets(file, buf, sizeof(buf))) {
+ if (strncmp(buf, "CONFIG_", 7))
+ continue;
+
+ sep = strchr(buf, '=');
+ if (!sep) {
+ err = -EINVAL;
+ pr_warn("failed to parse '%s': no separator\n", buf);
+ goto out;
+ }
+ /* Trim ending '\n' */
+ len = strlen(buf);
+ if (buf[len - 1] == '\n')
+ buf[len - 1] = '\0';
+ /* Split on '=' and ensure that a value is present. */
+ *sep = '\0';
+ if (!sep[1]) {
+ err = -EINVAL;
+ *sep = '=';
+ pr_warn("failed to parse '%s': no value\n", buf);
+ goto out;
+ }
+
+ ext = find_extern_by_name(obj, buf);
+ if (!ext)
+ continue;
+ if (ext->is_set) {
+ err = -EINVAL;
+ pr_warn("re-defining extern '%s' not allowed\n", buf);
+ goto out;
+ }
+
+ ext_val = data + ext->data_off;
+ value = sep + 1;
+
+ switch (*value) {
+ case 'y': case 'n': case 'm':
+ err = set_ext_value_tri(ext, ext_val, *value);
+ break;
+ case '"':
+ err = set_ext_value_str(ext, ext_val, value);
+ break;
+ default:
+ /* assume integer */
+ err = parse_u64(value, &num);
+ if (err) {
+ pr_warn("extern %s=%s should be integer\n",
+ ext->name, value);
+ goto out;
+ }
+ err = set_ext_value_num(ext, ext_val, num);
+ break;
+ }
+ if (err)
+ goto out;
+ pr_debug("extern %s=%s\n", ext->name, value);
+ }
+
+out:
+ gzclose(file);
+ return err;
+}
+
+static int bpf_object__init_extern_map(struct bpf_object *obj)
+{
+ struct extern_desc *last_ext;
+ size_t map_sz;
+ int err;
+
+ if (obj->nr_extern == 0)
+ return 0;
+
+ last_ext = &obj->externs[obj->nr_extern - 1];
+ map_sz = last_ext->data_off + last_ext->sz;
+
+ err = bpf_object__init_internal_map(obj, LIBBPF_MAP_EXTERN,
+ obj->efile.symbols_shndx,
+ NULL, map_sz);
+ if (err)
+ return err;
+
+ obj->extern_map_idx = obj->nr_maps - 1;
+
+ return 0;
+}
+
static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
{
Elf_Data *symbols = obj->efile.symbols;
@@ -1401,19 +1705,17 @@ static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
static int bpf_object__init_maps(struct bpf_object *obj,
const struct bpf_object_open_opts *opts)
{
- const char *pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
- bool strict = !OPTS_GET(opts, relaxed_maps, false);
+ const char *pin_root_path;
+ bool strict;
int err;
- err = bpf_object__init_user_maps(obj, strict);
- if (err)
- return err;
+ strict = !OPTS_GET(opts, relaxed_maps, false);
+ pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
- err = bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
- if (err)
- return err;
-
- err = bpf_object__init_global_data_maps(obj);
+ err = bpf_object__init_user_maps(obj, strict);
+ err = err ?: bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
+ err = err ?: bpf_object__init_global_data_maps(obj);
+ err = err ?: bpf_object__init_extern_map(obj);
if (err)
return err;
@@ -1532,11 +1834,6 @@ static int bpf_object__init_btf(struct bpf_object *obj,
BTF_ELF_SEC, err);
goto out;
}
- err = btf__finalize_data(obj, obj->btf);
- if (err) {
- pr_warn("Error finalizing %s: %d.\n", BTF_ELF_SEC, err);
- goto out;
- }
}
if (btf_ext_data) {
if (!obj->btf) {
@@ -1570,6 +1867,30 @@ out:
return 0;
}
+static int bpf_object__finalize_btf(struct bpf_object *obj)
+{
+ int err;
+
+ if (!obj->btf)
+ return 0;
+
+ err = btf__finalize_data(obj, obj->btf);
+ if (!err)
+ return 0;
+
+ pr_warn("Error finalizing %s: %d.\n", BTF_ELF_SEC, err);
+ btf__free(obj->btf);
+ obj->btf = NULL;
+ btf_ext__free(obj->btf_ext);
+ obj->btf_ext = NULL;
+
+ if (bpf_object__is_btf_mandatory(obj)) {
+ pr_warn("BTF is required, but is missing or corrupted.\n");
+ return -ENOENT;
+ }
+ return 0;
+}
+
static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
{
int err = 0;
@@ -1670,6 +1991,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
return -LIBBPF_ERRNO__FORMAT;
}
obj->efile.symbols = data;
+ obj->efile.symbols_shndx = idx;
obj->efile.strtabidx = sh.sh_link;
} else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) {
if (sh.sh_flags & SHF_EXECINSTR) {
@@ -1737,6 +2059,216 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
return bpf_object__init_btf(obj, btf_data, btf_ext_data);
}
+static bool sym_is_extern(const GElf_Sym *sym)
+{
+ int bind = GELF_ST_BIND(sym->st_info);
+ /* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */
+ return sym->st_shndx == SHN_UNDEF &&
+ (bind == STB_GLOBAL || bind == STB_WEAK) &&
+ GELF_ST_TYPE(sym->st_info) == STT_NOTYPE;
+}
+
+static int find_extern_btf_id(const struct btf *btf, const char *ext_name)
+{
+ const struct btf_type *t;
+ const char *var_name;
+ int i, n;
+
+ if (!btf)
+ return -ESRCH;
+
+ n = btf__get_nr_types(btf);
+ for (i = 1; i <= n; i++) {
+ t = btf__type_by_id(btf, i);
+
+ if (!btf_is_var(t))
+ continue;
+
+ var_name = btf__name_by_offset(btf, t->name_off);
+ if (strcmp(var_name, ext_name))
+ continue;
+
+ if (btf_var(t)->linkage != BTF_VAR_GLOBAL_EXTERN)
+ return -EINVAL;
+
+ return i;
+ }
+
+ return -ENOENT;
+}
+
+static enum extern_type find_extern_type(const struct btf *btf, int id,
+ bool *is_signed)
+{
+ const struct btf_type *t;
+ const char *name;
+
+ t = skip_mods_and_typedefs(btf, id, NULL);
+ name = btf__name_by_offset(btf, t->name_off);
+
+ if (is_signed)
+ *is_signed = false;
+ switch (btf_kind(t)) {
+ case BTF_KIND_INT: {
+ int enc = btf_int_encoding(t);
+
+ if (enc & BTF_INT_BOOL)
+ return t->size == 1 ? EXT_BOOL : EXT_UNKNOWN;
+ if (is_signed)
+ *is_signed = enc & BTF_INT_SIGNED;
+ if (t->size == 1)
+ return EXT_CHAR;
+ if (t->size < 1 || t->size > 8 || (t->size & (t->size - 1)))
+ return EXT_UNKNOWN;
+ return EXT_INT;
+ }
+ case BTF_KIND_ENUM:
+ if (t->size != 4)
+ return EXT_UNKNOWN;
+ if (strcmp(name, "libbpf_tristate"))
+ return EXT_UNKNOWN;
+ return EXT_TRISTATE;
+ case BTF_KIND_ARRAY:
+ if (btf_array(t)->nelems == 0)
+ return EXT_UNKNOWN;
+ if (find_extern_type(btf, btf_array(t)->type, NULL) != EXT_CHAR)
+ return EXT_UNKNOWN;
+ return EXT_CHAR_ARR;
+ default:
+ return EXT_UNKNOWN;
+ }
+}
+
+static int cmp_externs(const void *_a, const void *_b)
+{
+ const struct extern_desc *a = _a;
+ const struct extern_desc *b = _b;
+
+ /* descending order by alignment requirements */
+ if (a->align != b->align)
+ return a->align > b->align ? -1 : 1;
+ /* ascending order by size, within same alignment class */
+ if (a->sz != b->sz)
+ return a->sz < b->sz ? -1 : 1;
+ /* resolve ties by name */
+ return strcmp(a->name, b->name);
+}
+
+static int bpf_object__collect_externs(struct bpf_object *obj)
+{
+ const struct btf_type *t;
+ struct extern_desc *ext;
+ int i, n, off, btf_id;
+ struct btf_type *sec;
+ const char *ext_name;
+ Elf_Scn *scn;
+ GElf_Shdr sh;
+
+ if (!obj->efile.symbols)
+ return 0;
+
+ scn = elf_getscn(obj->efile.elf, obj->efile.symbols_shndx);
+ if (!scn)
+ return -LIBBPF_ERRNO__FORMAT;
+ if (gelf_getshdr(scn, &sh) != &sh)
+ return -LIBBPF_ERRNO__FORMAT;
+ n = sh.sh_size / sh.sh_entsize;
+
+ pr_debug("looking for externs among %d symbols...\n", n);
+ for (i = 0; i < n; i++) {
+ GElf_Sym sym;
+
+ if (!gelf_getsym(obj->efile.symbols, i, &sym))
+ return -LIBBPF_ERRNO__FORMAT;
+ if (!sym_is_extern(&sym))
+ continue;
+ ext_name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
+ sym.st_name);
+ if (!ext_name || !ext_name[0])
+ continue;
+
+ ext = obj->externs;
+ ext = reallocarray(ext, obj->nr_extern + 1, sizeof(*ext));
+ if (!ext)
+ return -ENOMEM;
+ obj->externs = ext;
+ ext = &ext[obj->nr_extern];
+ memset(ext, 0, sizeof(*ext));
+ obj->nr_extern++;
+
+ ext->btf_id = find_extern_btf_id(obj->btf, ext_name);
+ if (ext->btf_id <= 0) {
+ pr_warn("failed to find BTF for extern '%s': %d\n",
+ ext_name, ext->btf_id);
+ return ext->btf_id;
+ }
+ t = btf__type_by_id(obj->btf, ext->btf_id);
+ ext->name = btf__name_by_offset(obj->btf, t->name_off);
+ ext->sym_idx = i;
+ ext->is_weak = GELF_ST_BIND(sym.st_info) == STB_WEAK;
+ ext->sz = btf__resolve_size(obj->btf, t->type);
+ if (ext->sz <= 0) {
+ pr_warn("failed to resolve size of extern '%s': %d\n",
+ ext_name, ext->sz);
+ return ext->sz;
+ }
+ ext->align = btf__align_of(obj->btf, t->type);
+ if (ext->align <= 0) {
+ pr_warn("failed to determine alignment of extern '%s': %d\n",
+ ext_name, ext->align);
+ return -EINVAL;
+ }
+ ext->type = find_extern_type(obj->btf, t->type,
+ &ext->is_signed);
+ if (ext->type == EXT_UNKNOWN) {
+ pr_warn("extern '%s' type is unsupported\n", ext_name);
+ return -ENOTSUP;
+ }
+ }
+ pr_debug("collected %d externs total\n", obj->nr_extern);
+
+ if (!obj->nr_extern)
+ return 0;
+
+ /* sort externs by (alignment, size, name) and calculate their offsets
+ * within a map */
+ qsort(obj->externs, obj->nr_extern, sizeof(*ext), cmp_externs);
+ off = 0;
+ for (i = 0; i < obj->nr_extern; i++) {
+ ext = &obj->externs[i];
+ ext->data_off = roundup(off, ext->align);
+ off = ext->data_off + ext->sz;
+ pr_debug("extern #%d: symbol %d, off %u, name %s\n",
+ i, ext->sym_idx, ext->data_off, ext->name);
+ }
+
+ btf_id = btf__find_by_name(obj->btf, EXTERN_SEC);
+ if (btf_id <= 0) {
+ pr_warn("no BTF info found for '%s' datasec\n", EXTERN_SEC);
+ return -ESRCH;
+ }
+
+ sec = (struct btf_type *)btf__type_by_id(obj->btf, btf_id);
+ sec->size = off;
+ n = btf_vlen(sec);
+ for (i = 0; i < n; i++) {
+ struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
+
+ t = btf__type_by_id(obj->btf, vs->type);
+ ext_name = btf__name_by_offset(obj->btf, t->name_off);
+ ext = find_extern_by_name(obj, ext_name);
+ if (!ext) {
+ pr_warn("failed to find extern definition for BTF var '%s'\n",
+ ext_name);
+ return -ESRCH;
+ }
+ vs->offset = ext->data_off;
+ btf_var(t)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
+ }
+
+ return 0;
+}
+
static struct bpf_program *
bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
{
@@ -1801,6 +2333,8 @@ bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
return LIBBPF_MAP_BSS;
else if (shndx == obj->efile.rodata_shndx)
return LIBBPF_MAP_RODATA;
+ else if (shndx == obj->efile.symbols_shndx)
+ return LIBBPF_MAP_EXTERN;
else
return LIBBPF_MAP_UNSPEC;
}
@@ -1845,6 +2379,30 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
insn_idx, insn->code);
return -LIBBPF_ERRNO__RELOC;
}
+
+ if (sym_is_extern(sym)) {
+ int sym_idx = GELF_R_SYM(rel->r_info);
+ int i, n = obj->nr_extern;
+ struct extern_desc *ext;
+
+ for (i = 0; i < n; i++) {
+ ext = &obj->externs[i];
+ if (ext->sym_idx == sym_idx)
+ break;
+ }
+ if (i >= n) {
+ pr_warn("extern relo failed to find extern for sym %d\n",
+ sym_idx);
+ return -LIBBPF_ERRNO__RELOC;
+ }
+ pr_debug("found extern #%d '%s' (sym %d, off %u) for insn %u\n",
+ i, ext->name, ext->sym_idx, ext->data_off, insn_idx);
+ reloc_desc->type = RELO_EXTERN;
+ reloc_desc->insn_idx = insn_idx;
+ reloc_desc->sym_off = ext->data_off;
+ return 0;
+ }
+
if (!shdr_idx || shdr_idx >= SHN_LORESERVE) {
pr_warn("invalid relo for \'%s\' in special section 0x%x; forgot to initialize global var?..\n",
name, shdr_idx);
@@ -2306,11 +2864,12 @@ bpf_object__reuse_map(struct bpf_map *map)
static int
bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
{
+ enum libbpf_map_type map_type = map->libbpf_type;
char *cp, errmsg[STRERR_BUFSIZE];
int err, zero = 0;
- /* Nothing to do here since kernel already zero-initializes .bss map. */
- if (map->libbpf_type == LIBBPF_MAP_BSS)
+ /* kernel already zero-initializes .bss map. */
+ if (map_type == LIBBPF_MAP_BSS)
return 0;
err = bpf_map_update_elem(map->fd, &zero, map->mmaped, 0);
@@ -2322,8 +2881,8 @@ bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
return err;
}
- /* Freeze .rodata map as read-only from syscall side. */
- if (map->libbpf_type == LIBBPF_MAP_RODATA) {
+ /* Freeze .rodata and .extern map as read-only from syscall side. */
+ if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_EXTERN) {
err = bpf_map_freeze(map->fd);
if (err) {
err = -errno;
@@ -3572,9 +4131,6 @@ bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
size_t new_cnt;
int err;
- if (relo->type != RELO_CALL)
- return -LIBBPF_ERRNO__RELOC;
-
if (prog->idx == obj->efile.text_shndx) {
pr_warn("relo in .text insn %d into off %d (insn #%d)\n",
relo->insn_idx, relo->sym_off, relo->sym_off / 8);
@@ -3636,27 +4192,37 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
for (i = 0; i < prog->nr_reloc; i++) {
struct reloc_desc *relo = &prog->reloc_desc[i];
+ struct bpf_insn *insn = &prog->insns[relo->insn_idx];
- if (relo->type == RELO_LD64 || relo->type == RELO_DATA) {
- struct bpf_insn *insn = &prog->insns[relo->insn_idx];
-
- if (relo->insn_idx + 1 >= (int)prog->insns_cnt) {
- pr_warn("relocation out of range: '%s'\n",
- prog->section_name);
- return -LIBBPF_ERRNO__RELOC;
- }
+ if (relo->insn_idx + 1 >= (int)prog->insns_cnt) {
+ pr_warn("relocation out of range: '%s'\n",
+ prog->section_name);
+ return -LIBBPF_ERRNO__RELOC;
+ }
- if (relo->type != RELO_DATA) {
- insn[0].src_reg = BPF_PSEUDO_MAP_FD;
- } else {
- insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
- insn[1].imm = insn[0].imm + relo->sym_off;
- }
+ switch (relo->type) {
+ case RELO_LD64:
+ insn[0].src_reg = BPF_PSEUDO_MAP_FD;
+ insn[0].imm = obj->maps[relo->map_idx].fd;
+ break;
+ case RELO_DATA:
+ insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
+ insn[1].imm = insn[0].imm + relo->sym_off;
insn[0].imm = obj->maps[relo->map_idx].fd;
- } else if (relo->type == RELO_CALL) {
+ break;
+ case RELO_EXTERN:
+ insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
+ insn[0].imm = obj->maps[obj->extern_map_idx].fd;
+ insn[1].imm = relo->sym_off;
+ break;
+ case RELO_CALL:
err = bpf_program__reloc_text(prog, obj, relo);
if (err)
return err;
+ break;
+ default:
+ pr_warn("relo #%d: bad relo type %d\n", i, relo->type);
+ return -EINVAL;
}
}
@@ -3936,11 +4502,10 @@ static struct bpf_object *
__bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
const struct bpf_object_open_opts *opts)
{
+ const char *obj_name, *kconfig_path;
struct bpf_program *prog;
struct bpf_object *obj;
- const char *obj_name;
char tmp_name[64];
- __u32 attach_prog_fd;
int err;
if (elf_version(EV_CURRENT) == EV_NONE) {
@@ -3969,11 +4534,18 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
return obj;
obj->relaxed_core_relocs = OPTS_GET(opts, relaxed_core_relocs, false);
- attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0);
+ kconfig_path = OPTS_GET(opts, kconfig_path, NULL);
+ if (kconfig_path) {
+ obj->kconfig_path = strdup(kconfig_path);
+ if (!obj->kconfig_path)
+ return ERR_PTR(-ENOMEM);
+ }
err = bpf_object__elf_init(obj);
err = err ? : bpf_object__check_endianness(obj);
err = err ? : bpf_object__elf_collect(obj);
+ err = err ? : bpf_object__collect_externs(obj);
+ err = err ? : bpf_object__finalize_btf(obj);
err = err ? : bpf_object__init_maps(obj, opts);
err = err ? : bpf_object__init_prog_names(obj);
err = err ? : bpf_object__collect_reloc(obj);
@@ -3996,7 +4568,7 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
bpf_program__set_type(prog, prog_type);
bpf_program__set_expected_attach_type(prog, attach_type);
if (prog_type == BPF_PROG_TYPE_TRACING)
- prog->attach_prog_fd = attach_prog_fd;
+ prog->attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0);
}
return obj;
@@ -4107,6 +4679,61 @@ static int bpf_object__sanitize_maps(struct bpf_object *obj)
return 0;
}
+static int bpf_object__resolve_externs(struct bpf_object *obj,
+ const char *config_path)
+{
+ bool need_config = false;
+ struct extern_desc *ext;
+ int err, i;
+ void *data;
+
+ if (obj->nr_extern == 0)
+ return 0;
+
+ data = obj->maps[obj->extern_map_idx].mmaped;
+
+ for (i = 0; i < obj->nr_extern; i++) {
+ ext = &obj->externs[i];
+
+ if (strcmp(ext->name, "LINUX_KERNEL_VERSION") == 0) {
+ void *ext_val = data + ext->data_off;
+ __u32 kver = get_kernel_version();
+
+ if (!kver) {
+ pr_warn("failed to get kernel version\n");
+ return -EINVAL;
+ }
+ err = set_ext_value_num(ext, ext_val, kver);
+ if (err)
+ return err;
+ pr_debug("extern %s=0x%x\n", ext->name, kver);
+ } else if (strncmp(ext->name, "CONFIG_", 7) == 0) {
+ need_config = true;
+ } else {
+ pr_warn("unrecognized extern '%s'\n", ext->name);
+ return -EINVAL;
+ }
+ }
+ if (need_config) {
+ err = bpf_object__read_kernel_config(obj, config_path, data);
+ if (err)
+ return -EINVAL;
+ }
+ for (i = 0; i < obj->nr_extern; i++) {
+ ext = &obj->externs[i];
+
+ if (!ext->is_set && !ext->is_weak) {
+ pr_warn("extern %s (strong) not resolved\n", ext->name);
+ return -ESRCH;
+ } else if (!ext->is_set) {
+ pr_debug("extern %s (weak) not resolved, defaulting to zero\n",
+ ext->name);
+ }
+ }
+
+ return 0;
+}
+
int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
{
struct bpf_object *obj;
@@ -4126,6 +4753,7 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
obj->loaded = true;
err = bpf_object__probe_caps(obj);
+ err = err ? : bpf_object__resolve_externs(obj, obj->kconfig_path);
err = err ? : bpf_object__sanitize_and_load_btf(obj);
err = err ? : bpf_object__sanitize_maps(obj);
err = err ? : bpf_object__create_maps(obj);
@@ -4719,6 +5347,10 @@ void bpf_object__close(struct bpf_object *obj)
zfree(&map->pin_path);
}
+ zfree(&obj->kconfig_path);
+ zfree(&obj->externs);
+ obj->nr_extern = 0;
+
zfree(&obj->maps);
obj->nr_maps = 0;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 623191e71415..6340823871e2 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -85,8 +85,12 @@ struct bpf_object_open_opts {
*/
const char *pin_root_path;
__u32 attach_prog_fd;
+ /* kernel config file path override (for CONFIG_ externs); can point
+ * to either uncompressed text file or .gz file
+ */
+ const char *kconfig_path;
};
-#define bpf_object_open_opts__last_field attach_prog_fd
+#define bpf_object_open_opts__last_field kconfig_path
LIBBPF_API struct bpf_object *bpf_object__open(const char *path);
LIBBPF_API struct bpf_object *
@@ -669,6 +673,12 @@ LIBBPF_API int bpf_object__attach_skeleton(struct bpf_object_skeleton *s);
LIBBPF_API void bpf_object__detach_skeleton(struct bpf_object_skeleton *s);
LIBBPF_API void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s);
+enum libbpf_tristate {
+ TRI_NO = 0,
+ TRI_YES = 1,
+ TRI_MODULE = 2,
+};
+
#ifdef __cplusplus
} /* extern "C" */
#endif
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index f70c8e735120..ba90621617a8 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -24,7 +24,7 @@ CFLAGS += -g -Wall -O2 $(GENFLAGS) -I$(APIDIR) -I$(LIBDIR) -I$(BPFDIR) \
-I$(GENDIR) -I$(TOOLSINCDIR) -I$(CURDIR) \
-Dbpf_prog_load=bpf_prog_test_load \
-Dbpf_load_program=bpf_test_load_program
-LDLIBS += -lcap -lelf -lrt -lpthread
+LDLIBS += -lcap -lelf -lz -lrt -lpthread
# Order correspond to 'make run_tests' order
TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.