[PATCH bpf-next v3 1/9] arm32, bpf: add support for 32-bit offset jmp instruction

[Puranjay Mohan]

The cpuv4 adds unconditional jump with 32-bit offset where the immediate
field of the instruction is to be used to calculate the jump offset.

BPF_JA | BPF_K | BPF_JMP32 => gotol +imm => PC += imm.

Signed-off-by: Puranjay Mohan <puranjay12@xxxxxxxxx>
Reviewed-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
---
 arch/arm/net/bpf_jit_32.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index 6a1c9fca5260..c03600fe86f6 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -1761,10 +1761,15 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
 		break;
 	/* JMP OFF */
 	case BPF_JMP | BPF_JA:
+	case BPF_JMP32 | BPF_JA:
 	{
-		if (off == 0)
+		if (BPF_CLASS(code) == BPF_JMP32 && imm != 0)
+			jmp_offset = bpf2a32_offset(i + imm, i, ctx);
+		else if (BPF_CLASS(code) == BPF_JMP && off != 0)
+			jmp_offset = bpf2a32_offset(i + off, i, ctx);
+		else
 			break;
-		jmp_offset = bpf2a32_offset(i+off, i, ctx);
+
 		check_imm24(jmp_offset);
 		emit(ARM_B(jmp_offset), ctx);
 		break;
-- 
2.39.2