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bpf: arm64: Add support for indirect jumps

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Add support for a new instruction

	BPF_JMP|BPF_X|BPF_JA, SRC=0, DST=Rx, off=0, imm=0

which does an indirect jump to a location stored in Rx.  The register
Rx should have type PTR_TO_INSN. This new type assures that the Rx
register contains a value (or a range of values) loaded from a
correct jump table – map of type instruction array.

ARM64 JIT supports indirect jumps to all registers through the A64_BR()
macro, use it to implement this new instruction.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20251117130732.11107-3-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Puranjay Mohan 2025-11-17 13:07:30 +00:00 committed by Alexei Starovoitov
parent 84b1c40d5b
commit f4a66cf1cb
1 changed files with 4 additions and 0 deletions
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4
arch/arm64/net/bpf_jit_comp.c
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@ -1452,6 +1452,10 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
emit(A64_ASR(is64, dst, dst, imm), ctx);
break;
/* JUMP reg */
case BPF_JMP | BPF_JA | BPF_X:
emit(A64_BR(dst), ctx);
break;
/* JUMP off */
case BPF_JMP | BPF_JA:
case BPF_JMP32 | BPF_JA: