arm32, bpf: add support for 32-bit offset jmp instruction

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@gmail.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://lore.kernel.org/r/20230907230550.1417590-2-puranjay12@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index 6a1c9fca5260b228b01010d77d1496f260a7bf96..c03600fe86f675f9da217fc6e20cd691eae5af7a 100644 (file)
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -1761,10 +1761,15 @@ go_jmp:
                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;