This patch shrinks the BTF_INT_BITS() mask. The current
btf_int_check_meta() ensures the nr_bits of an integer
cannot exceed 64. Hence, it is mostly an uapi cleanup.
The actual btf usage (i.e. seq_show()) is also modified
to use u8 instead of u16. The verification (e.g. btf_int_check_meta())
path stays as is to deal with invalid BTF situation.
Fixes: 69b693f0aefa ("bpf: btf: Introduce BPF Type Format (BTF)")
Signed-off-by: Martin KaFai Lau
---
include/uapi/linux/btf.h | 2 +-
kernel/bpf/btf.c | 16 ++--
2 files changed, 11 insertions(+), 7 deletions(-)
diff --git a/include/uapi/linux/btf.h b/include/uapi/linux/btf.h
index 0b5ddbe135a4..972265f32871 100644
--- a/include/uapi/linux/btf.h
+++ b/include/uapi/linux/btf.h
@@ -76,7 +76,7 @@ struct btf_type {
*/
#define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f00) >> 24)
#define BTF_INT_OFFSET(VAL)(((VAL & 0x00ff)) >> 16)
-#define BTF_INT_BITS(VAL) ((VAL) & 0x)
+#define BTF_INT_BITS(VAL) ((VAL) & 0x00ff)
/* Attributes stored in the BTF_INT_ENCODING */
#define BTF_INT_SIGNED (1 << 0)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index e016ac3afa24..9704934252b3 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -450,7 +450,7 @@ static const struct btf_type *btf_type_by_id(const struct
btf *btf, u32 type_id)
*/
static bool btf_type_int_is_regular(const struct btf_type *t)
{
- u16 nr_bits, nr_bytes;
+ u8 nr_bits, nr_bytes;
u32 int_data;
int_data = btf_type_int(t);
@@ -993,12 +993,16 @@ static void btf_int_bits_seq_show(const struct btf *btf,
{
u16 left_shift_bits, right_shift_bits;
u32 int_data = btf_type_int(t);
- u16 nr_bits = BTF_INT_BITS(int_data);
- u16 total_bits_offset;
- u16 nr_copy_bytes;
- u16 nr_copy_bits;
+ u8 nr_bits = BTF_INT_BITS(int_data);
+ u8 total_bits_offset;
+ u8 nr_copy_bytes;
+ u8 nr_copy_bits;
u64 print_num;
+ /*
+* bits_offset is at most 7.
+* BTF_INT_OFFSET() cannot exceed 64 bits.
+*/
total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data);
data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
bits_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
@@ -1028,7 +1032,7 @@ static void btf_int_seq_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;
- u32 nr_bits = BTF_INT_BITS(int_data);
+ u8 nr_bits = BTF_INT_BITS(int_data);
if (bits_offset || BTF_INT_OFFSET(int_data) ||
BITS_PER_BYTE_MASKED(nr_bits)) {
--
2.17.1
