btf: support ints larger than 128 bits

.travis.yml

@@ -0,0 +1,33 @@
+sudo: required
+language: bash
+dist: bionic
+services:
+    - docker
+
+env:
+    global:
+        - PROJECT_NAME='libbpf'
+        - AUTHOR_EMAIL="$(git log -1 --pretty=\"%aE\")"
+        - REPO_ROOT="$TRAVIS_BUILD_DIR"
+        - CI_ROOT="$REPO_ROOT/travis-ci"
+        - VMTEST_ROOT="$CI_ROOT/vmtest"
+
+addons:
+    apt:
+        packages:
+            - qemu-kvm
+            - zstd
+            - binutils-dev
+            - elfutils
+            - libcap-dev
+            - libelf-dev
+            - libdw-dev
+            - python3-docutils
+
+jobs:
+    include:
+        - stage: Builds & Tests
+          name: Kernel LATEST + selftests
+          language: bash
+          env: KERNEL=LATEST
+          script:  $CI_ROOT/vmtest/run_vmtest.sh || travis_terminate 1

Documentation/bpf/btf.rst

@@ -132,7 +132,7 @@ The following sections detail encoding of each kind.
 
   #define BTF_INT_ENCODING(VAL)   (((VAL) & 0x0f000000) >> 24)
   #define BTF_INT_OFFSET(VAL)     (((VAL) & 0x00ff0000) >> 16)
-  #define BTF_INT_BITS(VAL)       ((VAL)  & 0x000000ff)
+  #define BTF_INT_BITS(VAL)       ((VAL)  & 0x000003ff)
 
 The ``BTF_INT_ENCODING`` has the following attributes::
 
@@ -147,7 +147,7 @@ pretty print. At most one encoding can be specified for the int type.
 The ``BTF_INT_BITS()`` specifies the number of actual bits held by this int
 type. For example, a 4-bit bitfield encodes ``BTF_INT_BITS()`` equals to 4.
 The ``btf_type.size * 8`` must be equal to or greater than ``BTF_INT_BITS()``
-for the type. The maximum value of ``BTF_INT_BITS()`` is 128.
+for the type. The maximum value of ``BTF_INT_BITS()`` is 512.
 
 The ``BTF_INT_OFFSET()`` specifies the starting bit offset to calculate values
 for this int. For example, a bitfield struct member has:

include/uapi/linux/btf.h

@@ -84,7 +84,7 @@ struct btf_type {
  */
 #define BTF_INT_ENCODING(VAL)	(((VAL) & 0x0f000000) >> 24)
 #define BTF_INT_OFFSET(VAL)	(((VAL) & 0x00ff0000) >> 16)
-#define BTF_INT_BITS(VAL)	((VAL)  & 0x000000ff)
+#define BTF_INT_BITS(VAL)	((VAL)  & 0x000003ff)
 
 /* Attributes stored in the BTF_INT_ENCODING */
 #define BTF_INT_SIGNED	(1 << 0)

kernel/bpf/btf.c

@@ -166,7 +166,8 @@
  *
  */
 
-#define BITS_PER_U128 (sizeof(u64) * BITS_PER_BYTE * 2)
+#define BITS_PER_U128 128
+#define BITS_PER_U512 512
 #define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
 #define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
 #define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
@@ -1907,9 +1908,9 @@ static int btf_int_check_member(struct btf_verifier_env *env,
 	nr_copy_bits = BTF_INT_BITS(int_data) +
 		BITS_PER_BYTE_MASKED(struct_bits_off);
 
-	if (nr_copy_bits > BITS_PER_U128) {
+	if (nr_copy_bits > BITS_PER_U512) {
 		btf_verifier_log_member(env, struct_type, member,
-					"nr_copy_bits exceeds 128");
+					"nr_copy_bits exceeds 512");
 		return -EINVAL;
 	}
 
@@ -1963,9 +1964,9 @@ static int btf_int_check_kflag_member(struct btf_verifier_env *env,
 
 	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
 	nr_copy_bits = nr_bits + BITS_PER_BYTE_MASKED(struct_bits_off);
-	if (nr_copy_bits > BITS_PER_U128) {
+	if (nr_copy_bits > BITS_PER_U512) {
 		btf_verifier_log_member(env, struct_type, member,
-					"nr_copy_bits exceeds 128");
+					"nr_copy_bits exceeds 512");
 		return -EINVAL;
 	}
 
@@ -2012,9 +2013,9 @@ static s32 btf_int_check_meta(struct btf_verifier_env *env,
 
 	nr_bits = BTF_INT_BITS(int_data) + BTF_INT_OFFSET(int_data);
 
-	if (nr_bits > BITS_PER_U128) {
-		btf_verifier_log_type(env, t, "nr_bits exceeds %zu",
-				      BITS_PER_U128);
+	if (nr_bits > BITS_PER_U512) {
+		btf_verifier_log_type(env, t, "nr_bits exceeds %u",
+				      BITS_PER_U512);
 		return -EINVAL;
 	}
 
@@ -2080,6 +2081,37 @@ static void btf_int128_print(struct btf_show *show, void *data)
 				     lower_num);
 }
 
+static void btf_bigint_print(struct btf_show *show, void *data, u16 nr_bits)
+{
+	/* data points to 256 or 512 bit int type */
+	char buf[129];
+	int last_u64 = nr_bits / 64 - 1;
+	bool seen_nonzero = false;
+	int i;
+
+	for (i = 0; i <= last_u64; i++) {
+#ifdef __BIG_ENDIAN_BITFIELD
+		u64 v = ((u64 *)data)[i];
+#else
+		u64 v = ((u64 *)data)[last_u64 - i];
+#endif
+		if (!seen_nonzero) {
+			if (!v && i != last_u64)
+				continue;
+
+			snprintf(buf, sizeof(buf), "%llx", v);
+
+			seen_nonzero = true;
+		} else {
+			size_t off = strlen(buf);
+
+			snprintf(buf + off, sizeof(buf) - off, "%016llx", v);
+		}
+	}
+
+	btf_show_type_value(show, "0x%s", buf);
+}
+
 static void btf_int128_shift(u64 *print_num, u16 left_shift_bits,
 			     u16 right_shift_bits)
 {
@@ -2172,7 +2204,7 @@ static void btf_int_show(const struct btf *btf, const struct btf_type *t,
 	u32 int_data = btf_type_int(t);
 	u8 encoding = BTF_INT_ENCODING(int_data);
 	bool sign = encoding & BTF_INT_SIGNED;
-	u8 nr_bits = BTF_INT_BITS(int_data);
+	u16 nr_bits = BTF_INT_BITS(int_data);
 	void *safe_data;
 
 	safe_data = btf_show_start_type(show, t, type_id, data);
@@ -2186,6 +2218,10 @@ static void btf_int_show(const struct btf *btf, const struct btf_type *t,
 	}
 
 	switch (nr_bits) {
+	case 512:
+	case 256:
+		btf_bigint_print(show, safe_data, nr_bits);
+		break;
 	case 128:
 		btf_int128_print(show, safe_data);
 		break;

tools/bpf/bpftool/btf_dumper.c

@@ -271,6 +271,41 @@ static void btf_int128_print(json_writer_t *jw, const void *data,
 	}
 }
 
+static void btf_bigint_print(json_writer_t *jw, const void *data, int nr_bits,
+			     bool is_plain_text)
+{
+	char buf[nr_bits / 4 + 1];
+	int last_u64 = nr_bits / 64 - 1;
+	bool seen_nonzero = false;
+	int i;
+
+	for (i = 0; i <= last_u64; i++) {
+#ifdef __BIG_ENDIAN_BITFIELD
+		__u64 v = ((__u64 *)data)[i];
+#else
+		__u64 v = ((__u64 *)data)[last_u64 - i];
+#endif
+
+		if (!seen_nonzero) {
+			if (!v && i != last_u64)
+				continue;
+
+			snprintf(buf, sizeof(buf), "%llx", v);
+
+			seen_nonzero = true;
+		} else {
+			size_t off = strlen(buf);
+
+			snprintf(buf + off, sizeof(buf) - off, "%016llx", v);
+		}
+	}
+
+	if (is_plain_text)
+		jsonw_printf(jw, "0x%s", buf);
+	else
+		jsonw_printf(jw, "\"0x%s\"", buf);
+}
+
 static void btf_int128_shift(__u64 *print_num, __u16 left_shift_bits,
 			     __u16 right_shift_bits)
 {
@@ -373,6 +408,11 @@ static int btf_dumper_int(const struct btf_type *t, __u8 bit_offset,
 		return 0;
 	}
 
+	if (nr_bits > 128) {
+		btf_bigint_print(jw, data, nr_bits, is_plain_text);
+		return 0;
+	}
+
 	if (nr_bits == 128) {
 		btf_int128_print(jw, data, is_plain_text);
 		return 0;

tools/include/uapi/linux/btf.h

@@ -84,7 +84,7 @@ struct btf_type {
  */
 #define BTF_INT_ENCODING(VAL)	(((VAL) & 0x0f000000) >> 24)
 #define BTF_INT_OFFSET(VAL)	(((VAL) & 0x00ff0000) >> 16)
-#define BTF_INT_BITS(VAL)	((VAL)  & 0x000000ff)
+#define BTF_INT_BITS(VAL)	((VAL)  & 0x000003ff)
 
 /* Attributes stored in the BTF_INT_ENCODING */
 #define BTF_INT_SIGNED	(1 << 0)

tools/lib/bpf/btf.c

@@ -1722,7 +1722,7 @@ int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding
 	if (!name || !name[0])
 		return -EINVAL;
 	/* byte_sz must be power of 2 */
-	if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 16)
+	if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 64)
 		return -EINVAL;
 	if (encoding & ~(BTF_INT_SIGNED | BTF_INT_CHAR | BTF_INT_BOOL))
 		return -EINVAL;

tools/testing/selftests/bpf/Makefile

@@ -70,7 +70,8 @@ TEST_PROGS := test_kmod.sh \
 	test_bpftool_build.sh \
 	test_bpftool.sh \
 	test_bpftool_metadata.sh \
-	test_xsk.sh
+	test_xsk.sh \
+	test_extint.py
 
 TEST_PROGS_EXTENDED := with_addr.sh \
 	with_tunnels.sh \

tools/testing/selftests/bpf/prog_tests/btf.c

@@ -4073,6 +4073,7 @@ struct btf_file_test {
 static struct btf_file_test file_tests[] = {
 	{ .file = "test_btf_haskv.o", },
 	{ .file = "test_btf_newkv.o", },
+	{ .file = "test_btf_extint.o", },
 	{ .file = "test_btf_nokv.o", .btf_kv_notfound = true, },
 };
 
@@ -4414,7 +4415,7 @@ static struct btf_raw_test pprint_test_template[] = {
 	 * will have both int and enum types.
 	 */
 	.raw_types = {
-		/* unsighed char */			/* [1] */
+		/* unsigned char */			/* [1] */
 		BTF_TYPE_INT_ENC(NAME_TBD, 0, 0, 8, 1),
 		/* unsigned short */			/* [2] */
 		BTF_TYPE_INT_ENC(NAME_TBD, 0, 0, 16, 2),

tools/testing/selftests/bpf/progs/test_btf_extint.c

@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_legacy.h"
+
+struct extint {
+	_ExtInt(256) v256;
+	_ExtInt(512) v512;
+};
+
+struct bpf_map_def SEC("maps") btf_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(int),
+	.value_size = sizeof(struct extint),
+	.max_entries = 1,
+};
+
+BPF_ANNOTATE_KV_PAIR(btf_map, int, struct extint);
+
+__attribute__((noinline))
+int test_long_fname_2(void)
+{
+	struct extint *bi;
+	int key = 0;
+
+	bi = bpf_map_lookup_elem(&btf_map, &key);
+	if (!bi)
+		return 0;
+
+	bi->v256 <<= 64;
+	bi->v256 += (_ExtInt(256))0xcafedead;
+	bi->v512 <<= 128;
+	bi->v512 += (_ExtInt(512))0xff00ff00ff00ffull;
+
+	return 0;
+}
+
+__attribute__((noinline))
+int test_long_fname_1(void)
+{
+	return test_long_fname_2();
+}
+
+SEC("dummy_tracepoint")
+int _dummy_tracepoint(void *arg)
+{
+	return test_long_fname_1();
+}
+
+char _license[] SEC("license") = "GPL";