From a1d3cc3c5eca598cfabee3a35f30f34fbe2f709b Mon Sep 17 00:00:00 2001 From: Alan Maguire Date: Tue, 20 Jul 2021 09:49:51 +0100 Subject: [PATCH] libbpf: Avoid use of __int128 in typed dump display __int128 is not supported for some 32-bit platforms (arm and i386). __int128 was used in carrying out computations on bitfields which aid display, but the same calculations could be done with __u64 with the small effect of not supporting 128-bit bitfields. With these changes, a big-endian issue with casting 128-bit integers to 64-bit for enum bitfields is solved also, as we now use 64-bit integers for bitfield calculations. Reported-by: Naresh Kamboju Reported-by: Linux Kernel Functional Testing Signed-off-by: Alan Maguire Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/1626770993-11073-2-git-send-email-alan.maguire@oracle.com --- tools/lib/bpf/btf_dump.c | 98 ++++++++++++++++++++++++++++++++---------------- 1 file changed, 65 insertions(+), 33 deletions(-) diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c index accf6fea57da..d52e546a515c 100644 --- a/tools/lib/bpf/btf_dump.c +++ b/tools/lib/bpf/btf_dump.c @@ -1552,31 +1552,26 @@ static int btf_dump_unsupported_data(struct btf_dump *d, return -ENOTSUP; } -static void btf_dump_int128(struct btf_dump *d, - const struct btf_type *t, - const void *data) -{ - __int128 num = *(__int128 *)data; - - if ((num >> 64) == 0) - btf_dump_type_values(d, "0x%llx", (long long)num); - else - btf_dump_type_values(d, "0x%llx%016llx", (long long)num >> 32, - (long long)num); -} - -static unsigned __int128 btf_dump_bitfield_get_data(struct btf_dump *d, - const struct btf_type *t, - const void *data, - __u8 bits_offset, - __u8 bit_sz) +static int btf_dump_get_bitfield_value(struct btf_dump *d, + const struct btf_type *t, + const void *data, + __u8 bits_offset, + __u8 bit_sz, + __u64 *value) { __u16 left_shift_bits, right_shift_bits; __u8 nr_copy_bits, nr_copy_bytes; - unsigned __int128 num = 0, ret; const __u8 *bytes = data; + int sz = t->size; + __u64 num = 0; int i; + /* Maximum supported bitfield size is 64 bits */ + if (sz > 8) { + pr_warn("unexpected bitfield size %d\n", sz); + return -EINVAL; + } + /* Bitfield value retrieval is done in two steps; first relevant bytes are * stored in num, then we left/right shift num to eliminate irrelevant bits. */ @@ -1591,12 +1586,12 @@ static unsigned __int128 btf_dump_bitfield_get_data(struct btf_dump *d, #else # error "Unrecognized __BYTE_ORDER__" #endif - left_shift_bits = 128 - nr_copy_bits; - right_shift_bits = 128 - bit_sz; + left_shift_bits = 64 - nr_copy_bits; + right_shift_bits = 64 - bit_sz; - ret = (num << left_shift_bits) >> right_shift_bits; + *value = (num << left_shift_bits) >> right_shift_bits; - return ret; + return 0; } static int btf_dump_bitfield_check_zero(struct btf_dump *d, @@ -1605,9 +1600,12 @@ static int btf_dump_bitfield_check_zero(struct btf_dump *d, __u8 bits_offset, __u8 bit_sz) { - __int128 check_num; + __u64 check_num; + int err; - check_num = btf_dump_bitfield_get_data(d, t, data, bits_offset, bit_sz); + err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, &check_num); + if (err) + return err; if (check_num == 0) return -ENODATA; return 0; @@ -1619,10 +1617,14 @@ static int btf_dump_bitfield_data(struct btf_dump *d, __u8 bits_offset, __u8 bit_sz) { - unsigned __int128 print_num; + __u64 print_num; + int err; + + err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, &print_num); + if (err) + return err; - print_num = btf_dump_bitfield_get_data(d, t, data, bits_offset, bit_sz); - btf_dump_int128(d, t, &print_num); + btf_dump_type_values(d, "0x%llx", (unsigned long long)print_num); return 0; } @@ -1681,9 +1683,29 @@ static int btf_dump_int_data(struct btf_dump *d, return btf_dump_bitfield_data(d, t, data, 0, 0); switch (sz) { - case 16: - btf_dump_int128(d, t, data); + case 16: { + const __u64 *ints = data; + __u64 lsi, msi; + + /* avoid use of __int128 as some 32-bit platforms do not + * support it. + */ +#if __BYTE_ORDER == __LITTLE_ENDIAN + lsi = ints[0]; + msi = ints[1]; +#elif __BYTE_ORDER == __BIG_ENDIAN + lsi = ints[1]; + msi = ints[0]; +#else +# error "Unrecognized __BYTE_ORDER__" +#endif + if (msi == 0) + btf_dump_type_values(d, "0x%llx", (unsigned long long)lsi); + else + btf_dump_type_values(d, "0x%llx%016llx", (unsigned long long)msi, + (unsigned long long)lsi); break; + } case 8: if (sign) btf_dump_type_values(d, "%lld", *(long long *)data); @@ -1931,9 +1953,16 @@ static int btf_dump_get_enum_value(struct btf_dump *d, /* handle unaligned enum value */ if (!ptr_is_aligned(data, sz)) { - *value = (__s64)btf_dump_bitfield_get_data(d, t, data, 0, 0); + __u64 val; + int err; + + err = btf_dump_get_bitfield_value(d, t, data, 0, 0, &val); + if (err) + return err; + *value = (__s64)val; return 0; } + switch (t->size) { case 8: *value = *(__s64 *)data; @@ -2209,10 +2238,13 @@ static int btf_dump_dump_type_data(struct btf_dump *d, case BTF_KIND_ENUM: /* handle bitfield and int enum values */ if (bit_sz) { - unsigned __int128 print_num; + __u64 print_num; __s64 enum_val; - print_num = btf_dump_bitfield_get_data(d, t, data, bits_offset, bit_sz); + err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, + &print_num); + if (err) + break; enum_val = (__s64)print_num; err = btf_dump_enum_data(d, t, id, &enum_val); } else -- 2.11.0