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## example showing mmap syscall
# Create a new segment using mmap, save the address, write to it.
#
# To run (from the subx directory):
# $ subx translate examples/ex12.subx -o examples/ex12
# $ subx run examples/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&
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