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[bpf] allow direct and indirect calls

Description

[bpf] allow direct and indirect calls

kernel verifier is becoming smarter and soon will support
direct and indirect function calls.
Remove obsolete error from BPF backend.
Make call to use PCRel_4 fixup.
'bpf to bpf' calls are distinguished from 'bpf to kernel' calls
by insn->src_reg == BPF_PSEUDO_CALL == 1 which is used as relocation
indicator similar to ld_imm64->src_reg == BPF_PSEUDO_MAP_FD == 1
The actual 'call' instruction remains the same for both
'bpf to kernel' and 'bpf to bpf' calls.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Details

Committed
astNov 18 2017, 5:35 PM
Parents
rL318613: [X86] Switch cannonlake to use the SkylakeServer scheduling model instead of…
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