diff options
Diffstat (limited to 'subx/examples')
| -rwxr-xr-x | subx/examples/ex12 | bin | 0 -> 167 bytes | |||
| -rw-r--r-- | subx/examples/ex12.subx | 43 |
2 files changed, 43 insertions, 0 deletions
diff --git a/subx/examples/ex12 b/subx/examples/ex12 new file mode 100755 index 00000000..236afe98 --- /dev/null +++ b/subx/examples/ex12 Binary files differdiff --git a/subx/examples/ex12.subx b/subx/examples/ex12.subx new file mode 100644 index 00000000..50c57928 --- /dev/null +++ b/subx/examples/ex12.subx @@ -0,0 +1,43 @@ +## example showing mmap syscall +# Create a new segment using mmap, save the address, write to it. +# +# To run: +# $ subx translate ex12.subx ex12 +# $ subx run ex12 +# You shouldn't get a segmentation fault. + +== 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 + + # mmap(0x1000) + bb/copy . . . . . . . mmap_new_segment/imm32 # copy to EBX + b8/copy . . . . . . . 0x5a/imm32/mmap # copy 8 to EAX + cd/syscall 0x80/imm8 + + # store to *EAX + c7/copy 0/mod/direct 0/rm32/EAX . . . . . 0x34/imm32 # copy 0x34 to *EAX + + # exit(EAX) + 89/copy 3/mod/direct 3/rm32/EBX . . . 0/r32/EAX . . # copy EAX to EBX + b8/copy . . . . . . . 1/imm32/exit # copy 1 to EAX + cd/syscall 0x80/imm8 + +== 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 01 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:ft=subx:nowrap:tw& |