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bpf: free up BPF_JMP | BPF_CALL | BPF_X opcode

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free up BPF_JMP | BPF_CALL | BPF_X opcode to be used by actual
indirect call by register and use kernel internal opcode to
mark call instruction into bpf_tail_call() helper.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov
2017-05-30 13:31:27 -07:00
committed by David S. Miller
parent d2e0ef493a
commit 71189fa9b0
8 changed files with 10 additions and 7 deletions
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2
kernel/bpf/core.c
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@@ -824,7 +824,7 @@ static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
[BPF_ALU64 | BPF_NEG] = &&ALU64_NEG,
/* Call instruction */
[BPF_JMP | BPF_CALL] = &&JMP_CALL,
[BPF_JMP | BPF_CALL | BPF_X] = &&JMP_TAIL_CALL,
[BPF_JMP | BPF_TAIL_CALL] = &&JMP_TAIL_CALL,
/* Jumps */
[BPF_JMP | BPF_JA] = &&JMP_JA,
[BPF_JMP | BPF_JEQ | BPF_X] = &&JMP_JEQ_X,

2
kernel/bpf/verifier.c
View File

@@ -3469,7 +3469,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
* that doesn't support bpf_tail_call yet
*/
insn->imm = 0;
insn->code |= BPF_X;
insn->code = BPF_JMP | BPF_TAIL_CALL;
continue;
}