The spec defines: > As discussed below in `64-bit immediate instructions`_, a 64-bit immediate > instruction uses a 64-bit immediate value that is constructed as follows. > The 64 bits following the basic instruction contain a pseudo instruction > using the same format but with opcode, dst_reg, src_reg, and offset all set to zero, > and imm containing the high 32 bits of the immediate value. [...] > imm64 = (next_imm << 32) | imm The 64-bit immediate instructions section then says: > Instructions with the ``BPF_IMM`` 'mode' modifier use the wide instruction > encoding defined in `Instruction encoding`_, and use the 'src' field of the > basic instruction to hold an opcode subtype. Some instructions then nicely state how to use the full 64 bit immediate value, such as > BPF_IMM | BPF_DW | BPF_LD 0x18 0x0 dst = imm64 integer integer > BPF_IMM | BPF_DW | BPF_LD 0x18 0x2 dst = map_val(map_by_fd(imm)) + next_imm map fd data pointer > BPF_IMM | BPF_DW | BPF_LD 0x18 0x6 dst = map_val(map_by_idx(imm)) + next_imm map index data pointer Others don't: > BPF_IMM | BPF_DW | BPF_LD 0x18 0x1 dst = map_by_fd(imm) map fd map > BPF_IMM | BPF_DW | BPF_LD 0x18 0x3 dst = var_addr(imm) variable id data pointer > BPF_IMM | BPF_DW | BPF_LD 0x18 0x4 dst = code_addr(imm) integer code pointer > BPF_IMM | BPF_DW | BPF_LD 0x18 0x5 dst = map_by_idx(imm) map index map How is next_imm used in those four? Must it be 0? Or can it be anything and it's ignored? Or is it used for something? Dave
