bpf, s390: add support for constant blinding

This patch adds recently added constant blinding helpers into the
s390 eBPF JIT. In the bpf_int_jit_compile() path, requirements are
to utilize bpf_jit_blind_constants()/bpf_jit_prog_release_other()
pair for rewriting the program into a blinded one, and to map the
BPF_REG_AX register to a CPU register. The mapping of BPF_REG_AX
is at r12 and similarly like in x86 case performs reloading when
ld_abs/ind is used. When blinding is not used, there's no additional
overhead in the generated image.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
1 file changed