leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity

libbpf: Avoid use of __int128 in typed dump display

Browse Source 
__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 <naresh.kamboju@linaro.org>
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1626770993-11073-2-git-send-email-alan.maguire@oracle.com
This commit is contained in:
Alan Maguire 2021-07-20 09:49:51 +01:00 committed by Andrii Nakryiko
parent 875fc315db
commit a1d3cc3c5e
1 changed files with 65 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

98
tools/lib/bpf/btf_dump.c
View File

@ -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;
print_num = btf_dump_bitfield_get_data(d, t, data, bits_offset, bit_sz);
btf_dump_int128(d, t, &print_num);
err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, &print_num);
if (err)
return err;
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