1 # Create a new segment (for data) using mmap(). 2 3 == code 4 # instruction effective address operand displacement immediate 5 # op subop mod rm32 base index scale r32 6 # 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes 7 8 # main: (manual test if this is the last file loaded) 9 # EAX = new-segment(0x1000) 10 # push args 11 68/push 0x1000/imm32 12 # call 13 e8/call new-segment/disp32 14 # discard args 15 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP 16 17 # store to *EAX 18 c7/copy 0/mod/direct 0/rm32/EAX . . . . . 0x34/imm32 # copy to *EAX 19 20 # exit(EAX) 21 89/copy 3/mod/direct 3/rm32/EBX . . . 0/r32/EAX . . # copy EAX to EBX 22 b8/copy-to-EAX 1/imm32/exit 23 cd/syscall 0x80/imm8 24 25 new-segment: # len : int -> address 26 # prolog 27 55/push-EBP 28 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP 29 53/push-EBX 30 # copy len to mmap-new-segment.len 31 # TODO: compute mmap-new-segment+4 before runtime 32 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 0/r32/EAX 8/disp8 . # copy *(EBP+8) to EAX 33 bb/copy-to-EBX mmap-new-segment/imm32 34 89/copy 1/mod/*+disp8 3/rm32/EBX . . . 0/r32/EAX 4/disp8 . # copy EAX to *(EBX+4) 35 # mmap(mmap-new-segment) 36 bb/copy-to-EBX mmap-new-segment/imm32 37 b8/copy-to-EAX 0x5a/imm32/mmap 38 cd/syscall 0x80/imm8 39 # epilog 40 5b/pop-to-EBX 41 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 42 5d/pop-to-EBP 43 c3/return 44 45 == data 46 47 # various constants used here were found in the Linux sources (search for file mman-common.h) 48 mmap-new-segment: # type mmap_arg_struct 49 # addr 50 00 00 00 00 # null 51 # len 52 00 00 00 00 # 0x1000 53 # protection flags 54 03 00 00 00 # PROT_READ | PROT_WRITE 55 # sharing flags 56 22 00 00 00 # MAP_PRIVATE | MAP_ANONYMOUS 57 # fd 58 ff ff ff ff # -1 since MAP_ANONYMOUS is specified 59 # offset 60 00 00 00 00 # 0 since MAP_ANONYMOUS is specified 61 62 # vim:nowrap:textwidth=0