diff options
Diffstat (limited to 'subx/053new_segment.subx')
| -rw-r--r-- | subx/053new_segment.subx | 86 |
1 files changed, 43 insertions, 43 deletions
diff --git a/subx/053new_segment.subx b/subx/053new_segment.subx index c9a710e3..69115575 100644 --- a/subx/053new_segment.subx +++ b/subx/053new_segment.subx @@ -1,62 +1,62 @@ # Create a new segment (for data) using mmap(). == code -# instruction effective address operand displacement immediate -# op subop mod rm32 base index scale r32 -# 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 +# instruction effective address operand displacement immediate +# op subop mod rm32 base index scale r32 +# 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 # main: (manual test if this is the last file loaded) - # EAX = new-segment(0x1000) + # EAX = new-segment(0x1000) # push args - 68/push 0x1000/imm32 + 68/push 0x1000/imm32 # call - e8/call new-segment/disp32 + e8/call new-segment/disp32 # discard args - 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP - # store to *EAX - c7/copy 0/mod/direct 0/rm32/EAX . . . . . 0x34/imm32 # copy to *EAX + # store to *EAX + c7/copy 0/mod/direct 0/rm32/EAX . . . . . 0x34/imm32 # copy to *EAX - # exit(EAX) - 89/copy 3/mod/direct 3/rm32/EBX . . . 0/r32/EAX . . # copy EAX to EBX - b8/copy-to-EAX 1/imm32/exit - cd/syscall 0x80/imm8 + # exit(EAX) + 89/copy 3/mod/direct 3/rm32/EBX . . . 0/r32/EAX . . # copy EAX to EBX + b8/copy-to-EAX 1/imm32/exit + cd/syscall 0x80/imm8 new-segment: # len : int -> address - # prolog - 55/push-EBP - 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP - 53/push-EBX - # copy len to mmap-new-segment.len - # TODO: compute mmap-new-segment+4 before runtime - 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 0/r32/EAX 8/disp8 . # copy *(EBP+8) to EAX - bb/copy-to-EBX mmap-new-segment/imm32 - 89/copy 1/mod/*+disp8 3/rm32/EBX . . . 0/r32/EAX 4/disp8 . # copy EAX to *(EBX+4) - # mmap(mmap-new-segment) - bb/copy-to-EBX mmap-new-segment/imm32 - b8/copy-to-EAX 0x5a/imm32/mmap - cd/syscall 0x80/imm8 - # epilog - 5b/pop-to-EBX - 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP - 5d/pop-to-EBP - c3/return + # prolog + 55/push-EBP + 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP + 53/push-EBX + # copy len to mmap-new-segment.len + # TODO: compute mmap-new-segment+4 before runtime + 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 0/r32/EAX 8/disp8 . # copy *(EBP+8) to EAX + bb/copy-to-EBX mmap-new-segment/imm32 + 89/copy 1/mod/*+disp8 3/rm32/EBX . . . 0/r32/EAX 4/disp8 . # copy EAX to *(EBX+4) + # mmap(mmap-new-segment) + bb/copy-to-EBX mmap-new-segment/imm32 + b8/copy-to-EAX 0x5a/imm32/mmap + cd/syscall 0x80/imm8 + # epilog + 5b/pop-to-EBX + 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP + 5d/pop-to-EBP + c3/return == data # various constants used here were found in the Linux sources (search for file mman-common.h) mmap-new-segment: # type mmap_arg_struct - # addr - 00 00 00 00 # null - # len - 00 00 00 00 # 0x1000 - # protection flags - 03 00 00 00 # PROT_READ | PROT_WRITE - # sharing flags - 22 00 00 00 # MAP_PRIVATE | MAP_ANONYMOUS - # fd - ff ff ff ff # -1 since MAP_ANONYMOUS is specified - # offset - 00 00 00 00 # 0 since MAP_ANONYMOUS is specified + # addr + 00 00 00 00 # null + # len + 00 00 00 00 # 0x1000 + # protection flags + 03 00 00 00 # PROT_READ | PROT_WRITE + # sharing flags + 22 00 00 00 # MAP_PRIVATE | MAP_ANONYMOUS + # fd + ff ff ff ff # -1 since MAP_ANONYMOUS is specified + # offset + 00 00 00 00 # 0 since MAP_ANONYMOUS is specified # vim:nowrap:textwidth=0 |