mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-09-13 14:14:37 +00:00
Code Issues Releases Wiki Activity

libbpf: Make BPF-side of USDT support work on big-endian machines

Browse source 
BPF_USDT_ARG_REG_DEREF handling always reads 8 bytes, regardless of
the actual argument size. On little-endian the relevant argument bits
end up in the lower bits of val, and later on the code that handles
all the argument types expects them to be there.

On big-endian they end up in the upper bits of val, breaking that
expectation. Fix by right-shifting val on big-endian.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220407214411.257260-3-iii@linux.ibm.com
This commit is contained in:
Ilya Leoshkevich 2022-04-07 23:44:10 +02:00 committed by Andrii Nakryiko
parent e1b6df598a
commit 6f403d9d53
1 changed files with 3 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
tools/lib/bpf/usdt.bpf.h
View file

@ -177,6 +177,9 @@ int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res)
err = bpf_probe_read_user(&val, sizeof(val), (void *)val + arg_spec->val_off);
if (err)
return err;
#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
val >>= arg_spec->arg_bitshift;
#endif
break;
default:
return -EINVAL;