Hi Leon,
In the following commit:
commit b83b936f3e9a3c63896852198a1814e90e68eef5
Author: Leon Hwang <hffilwlqm@xxxxxxxxx>
selftests/bpf: Add testcases for tailcall hierarchy fixing
you created 2 tests files that contain the following inline assembly.
asm volatile (""::"r+"(ret));
I presume the actual intent is to force the unused ret variable to
exist as a register.
When compiling that line in GCC it produces the following error:
progs/tailcall_bpf2bpf_hierarchy2.c: In function 'tailcall_bpf2bpf_hierarchy_2':
progs/tailcall_bpf2bpf_hierarchy2.c:66:9: error: input operand constraint contains '+'
66 | asm volatile (""::"r+"(ret));
| ^~~
After analysing the reasoning behind the error, the plausible solution
is to change the constraint to "+r" and move it from the input operands
list to output operands, i.e:
asm volatile ("":"+r"(ret));
Can you please confirm that this change would be complient with the test
semantics ?
Regards,
Cupertino
