1 # Create a new segment (for data) using mmap(). 2 3 == code 4 5 # instruction effective address operand displacement immediate 6 # op subop mod rm32 base index scale r32 7 # 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 8 9 # main: (manual test if this is the last file loaded) 10 # EAX = new-segment(0x1000) 11 # push args 12 68/push 0x1000/imm32 13 # call 14 e8/call new-segment/disp32 15 # discard args 16 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP 17 18 # store to *EAX 19 c7/copy 0/mod/direct 0/rm32/EAX . . . . . 0x34/imm32 # copy to *EAX 20 21 # exit(EAX) 22 89/copy 3/mod/direct 3/rm32/EBX . . . 0/r32/EAX . . # copy EAX to EBX 23 b8/copy-to-EAX 1/imm32/exit 24 cd/syscall 0x80/imm8 25 26 new-segment: # len : int -> address 27 # prolog 28 55/push-EBP 29 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP 30 53/push-EBX 31 # copy len to mmap-new-segment.len 32 # TODO: compute mmap-new-segment+4 before runtime 33 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 0/r32/EAX 8/disp8 . # copy *(EBP+8) to EAX 34 bb/copy-to-EBX mmap-new-segment/imm32 35 89/copy 1/mod/*+disp8 3/rm32/EBX . . . 0/r32/EAX 4/disp8 . # copy EAX to *(EBX+4) 36 # mmap(mmap-new-segment) 37 bb/copy-to-EBX mmap-new-segment/imm32 38 b8/copy-to-EAX 0x5a/imm32/mmap 39 cd/syscall 0x80/imm8 40 # epilog 41 5b/pop-to-EBX 42 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 43 5d/pop-to-EBP 44 c3/return 45 46 == data 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