From b1e8818cabf407a5a2cec696411b0bdfd7fd12f0 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Tue, 15 Jan 2019 17:07:47 -0800 Subject: [PATCH] bpf: btf: support 128 bit integer type Currently, btf only supports up to 64-bit integer. On the other hand, 128bit support for gcc and clang has existed for a long time. For example, both gcc 4.8 and llvm 3.7 supports types "__int128" and "unsigned __int128" for virtually all 64bit architectures including bpf. The requirement for __int128 support comes from two areas: . bpf program may use __int128. For example, some bcc tools (https://github.com/iovisor/bcc/tree/master/tools), mostly tcp v6 related, tcpstates.py, tcpaccept.py, etc., are using __int128 to represent the ipv6 addresses. . linux itself is using __int128 types. Hence supporting __int128 type in BTF is required for vmlinux BTF, which will be used by "compile once and run everywhere" and other projects. For 128bit integer, instead of base-10, hex numbers are pretty printed out as large decimal number is hard to decipher, e.g., for ipv6 addresses. Acked-by: Martin KaFai Lau Signed-off-by: Yonghong Song Signed-off-by: Daniel Borkmann --- kernel/bpf/btf.c | 104 +++++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 85 insertions(+), 19 deletions(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index a2f5364..022ef9c 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -157,7 +157,7 @@ * */ -#define BITS_PER_U64 (sizeof(u64) * BITS_PER_BYTE) +#define BITS_PER_U128 (sizeof(u64) * BITS_PER_BYTE * 2) #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) @@ -525,7 +525,7 @@ const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id) /* * Regular int is not a bit field and it must be either - * u8/u16/u32/u64. + * u8/u16/u32/u64 or __int128. */ static bool btf_type_int_is_regular(const struct btf_type *t) { @@ -538,7 +538,8 @@ static bool btf_type_int_is_regular(const struct btf_type *t) if (BITS_PER_BYTE_MASKED(nr_bits) || BTF_INT_OFFSET(int_data) || (nr_bytes != sizeof(u8) && nr_bytes != sizeof(u16) && - nr_bytes != sizeof(u32) && nr_bytes != sizeof(u64))) { + nr_bytes != sizeof(u32) && nr_bytes != sizeof(u64) && + nr_bytes != (2 * sizeof(u64)))) { return false; } @@ -1063,9 +1064,9 @@ 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_U64) { + if (nr_copy_bits > BITS_PER_U128) { btf_verifier_log_member(env, struct_type, member, - "nr_copy_bits exceeds 64"); + "nr_copy_bits exceeds 128"); return -EINVAL; } @@ -1119,9 +1120,9 @@ 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_U64) { + if (nr_copy_bits > BITS_PER_U128) { btf_verifier_log_member(env, struct_type, member, - "nr_copy_bits exceeds 64"); + "nr_copy_bits exceeds 128"); return -EINVAL; } @@ -1168,9 +1169,9 @@ 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_U64) { + if (nr_bits > BITS_PER_U128) { btf_verifier_log_type(env, t, "nr_bits exceeds %zu", - BITS_PER_U64); + BITS_PER_U128); return -EINVAL; } @@ -1211,31 +1212,93 @@ static void btf_int_log(struct btf_verifier_env *env, btf_int_encoding_str(BTF_INT_ENCODING(int_data))); } +static void btf_int128_print(struct seq_file *m, void *data) +{ + /* data points to a __int128 number. + * Suppose + * int128_num = *(__int128 *)data; + * The below formulas shows what upper_num and lower_num represents: + * upper_num = int128_num >> 64; + * lower_num = int128_num & 0xffffffffFFFFFFFFULL; + */ + u64 upper_num, lower_num; + +#ifdef __BIG_ENDIAN_BITFIELD + upper_num = *(u64 *)data; + lower_num = *(u64 *)(data + 8); +#else + upper_num = *(u64 *)(data + 8); + lower_num = *(u64 *)data; +#endif + if (upper_num == 0) + seq_printf(m, "0x%llx", lower_num); + else + seq_printf(m, "0x%llx%016llx", upper_num, lower_num); +} + +static void btf_int128_shift(u64 *print_num, u16 left_shift_bits, + u16 right_shift_bits) +{ + u64 upper_num, lower_num; + +#ifdef __BIG_ENDIAN_BITFIELD + upper_num = print_num[0]; + lower_num = print_num[1]; +#else + upper_num = print_num[1]; + lower_num = print_num[0]; +#endif + + /* shake out un-needed bits by shift/or operations */ + if (left_shift_bits >= 64) { + upper_num = lower_num << (left_shift_bits - 64); + lower_num = 0; + } else { + upper_num = (upper_num << left_shift_bits) | + (lower_num >> (64 - left_shift_bits)); + lower_num = lower_num << left_shift_bits; + } + + if (right_shift_bits >= 64) { + lower_num = upper_num >> (right_shift_bits - 64); + upper_num = 0; + } else { + lower_num = (lower_num >> right_shift_bits) | + (upper_num << (64 - right_shift_bits)); + upper_num = upper_num >> right_shift_bits; + } + +#ifdef __BIG_ENDIAN_BITFIELD + print_num[0] = upper_num; + print_num[1] = lower_num; +#else + print_num[0] = lower_num; + print_num[1] = upper_num; +#endif +} + static void btf_bitfield_seq_show(void *data, u8 bits_offset, u8 nr_bits, struct seq_file *m) { u16 left_shift_bits, right_shift_bits; u8 nr_copy_bytes; u8 nr_copy_bits; - u64 print_num; + u64 print_num[2] = {}; nr_copy_bits = nr_bits + bits_offset; nr_copy_bytes = BITS_ROUNDUP_BYTES(nr_copy_bits); - print_num = 0; - memcpy(&print_num, data, nr_copy_bytes); + memcpy(print_num, data, nr_copy_bytes); #ifdef __BIG_ENDIAN_BITFIELD left_shift_bits = bits_offset; #else - left_shift_bits = BITS_PER_U64 - nr_copy_bits; + left_shift_bits = BITS_PER_U128 - nr_copy_bits; #endif - right_shift_bits = BITS_PER_U64 - nr_bits; - - print_num <<= left_shift_bits; - print_num >>= right_shift_bits; + right_shift_bits = BITS_PER_U128 - nr_bits; - seq_printf(m, "0x%llx", print_num); + btf_int128_shift(print_num, left_shift_bits, right_shift_bits); + btf_int128_print(m, print_num); } @@ -1250,7 +1313,7 @@ static void btf_int_bits_seq_show(const struct btf *btf, /* * bits_offset is at most 7. - * BTF_INT_OFFSET() cannot exceed 64 bits. + * BTF_INT_OFFSET() cannot exceed 128 bits. */ total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data); data += BITS_ROUNDDOWN_BYTES(total_bits_offset); @@ -1274,6 +1337,9 @@ static void btf_int_seq_show(const struct btf *btf, const struct btf_type *t, } switch (nr_bits) { + case 128: + btf_int128_print(m, data); + break; case 64: if (sign) seq_printf(m, "%lld", *(s64 *)data); -- 2.7.4