mu/linux/ex12.subx

# Example showing mmap syscall.
# Create a new segment using mmap, save the address, write to it.
#
# To run:
#   $ bootstrap/bootstrap translate ex12.subx -o ex12
#   $ bootstrap/bootstrap run ex12
# You shouldn't get a segmentation fault.

== code
#   instruction                     effective address                                                   register    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

Entry:
    # mmap(Mmap-new-segment->len)
    bb/copy-to-ebx  Mmap-new-segment/imm32
    e8/call  syscall_mmap/disp32

    # write to *eax to check that we have access to the newly-allocated segment
    c7          0/subop/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
    e8/call  syscall_exit/disp32

== 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
    0/imm32
    # len
    0x100/imm32
    # protection flags
    3/imm32  # PROT_READ | PROT_WRITE
    # sharing flags
    0x22/imm32  # MAP_PRIVATE | MAP_ANONYMOUS
    # fd
    -1/imm32  # since MAP_ANONYMOUS is specified
    # offset
    0/imm32  # since MAP_ANONYMOUS is specified

# . . vim:nowrap:textwidth=0
4808 - clean up comments in all subx files 2018-12-01 00:45:15 +00:00			`# Example showing mmap syscall.`
4619 - new syscall: mmap() 2018-09-29 23:17:11 +00:00			`# Create a new segment using mmap, save the address, write to it.`
			`#`
5521 2019-08-20 06:45:04 +00:00			`# To run:`
. 2021-03-30 01:47:52 +00:00			`# $ bootstrap/bootstrap translate ex12.subx -o ex12`
7847 2021-03-04 08:24:24 +00:00			`# $ bootstrap/bootstrap run ex12`
4619 - new syscall: mmap() 2018-09-29 23:17:11 +00:00			`# You shouldn't get a segmentation fault.`

5647 - experimental support for swapping OS 2019-09-12 02:04:49 +00:00			`== code`
4802 Some automated commenting cleanup. Still needs more careful manual scanning. sed -i 's/^# 1-3/# . 1-3/' .subx /.subx sed -i 's/^# op/# . op/' .subx /.subx sed -i 's/# vim/# . . vim/' .subx /.subx sed -i 's/^ # push args/ # . . push args/' .subx /.subx sed -i 's/^ # discard args/ # . . discard args/' .subx /.subx sed -i 's/^ # call/ # . . call/' .subx /.subx sed -i 's/^ # prolog/ # . prolog/' .subx /.subx sed -i 's/^ # epilog/ # . epilog/' .subx /.subx sed -i 's/^ # save registers/ # . save registers/' .subx /.subx sed -i 's/^ # restore registers/ # . restore registers/' .subx /.subx sed -i 's/ operand / register /' .subx /*.subx 2018-11-30 19:10:44 +00:00			`# instruction effective address register 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`
4619 - new syscall: mmap() 2018-09-29 23:17:11 +00:00
5410 - 4 examples passing Clean up other examples as well to satisfy the requirements in commit 5404. 2019-07-17 07:47:11 +00:00			`Entry:`
5647 - experimental support for swapping OS 2019-09-12 02:04:49 +00:00			`# mmap(Mmap-new-segment->len)`
5592 - switch register names to lowercase 2019-08-26 18:55:26 +00:00			`bb/copy-to-ebx Mmap-new-segment/imm32`
5647 - experimental support for swapping OS 2019-09-12 02:04:49 +00:00			`e8/call syscall_mmap/disp32`
4619 - new syscall: mmap() 2018-09-29 23:17:11 +00:00
5592 - switch register names to lowercase 2019-08-26 18:55:26 +00:00			`# write to *eax to check that we have access to the newly-allocated segment`
			`c7 0/subop/copy 0/mod/direct 0/rm32/eax . . . . . 0x34/imm32 # copy to *eax`
4619 - new syscall: mmap() 2018-09-29 23:17:11 +00:00
5647 - experimental support for swapping OS 2019-09-12 02:04:49 +00:00			`# exit(eax)`
5592 - switch register names to lowercase 2019-08-26 18:55:26 +00:00			`89/copy 3/mod/direct 3/rm32/ebx . . . 0/r32/eax . . # copy eax to ebx`
5647 - experimental support for swapping OS 2019-09-12 02:04:49 +00:00			`e8/call syscall_exit/disp32`
4619 - new syscall: mmap() 2018-09-29 23:17:11 +00:00
5647 - experimental support for swapping OS 2019-09-12 02:04:49 +00:00			`== data`
4780 2018-11-26 08:26:20 +00:00
4619 - new syscall: mmap() 2018-09-29 23:17:11 +00:00			`# various constants used here were found in the Linux sources (search for file mman-common.h)`
4757 Let's start highlighting all global variables in Red. Assembly programming has a tendency to over-use them. They're a necessary evil, but we should minimize the number of functions that access them. 2018-11-21 03:37:00 +00:00			`Mmap-new-segment: # type mmap_arg_struct`
4801 Reindent all SubX code to make some room for the new comment style. 2018-11-30 18:54:42 +00:00			`# addr`
4973 Support immediate operands in the data segment in all the ways we support them in the code segment. 2019-02-16 01:20:57 +00:00			`0/imm32`
4801 Reindent all SubX code to make some room for the new comment style. 2018-11-30 18:54:42 +00:00			`# len`
4973 Support immediate operands in the data segment in all the ways we support them in the code segment. 2019-02-16 01:20:57 +00:00			`0x100/imm32`
4801 Reindent all SubX code to make some room for the new comment style. 2018-11-30 18:54:42 +00:00			`# protection flags`
4973 Support immediate operands in the data segment in all the ways we support them in the code segment. 2019-02-16 01:20:57 +00:00			`3/imm32 # PROT_READ \| PROT_WRITE`
4801 Reindent all SubX code to make some room for the new comment style. 2018-11-30 18:54:42 +00:00			`# sharing flags`
4973 Support immediate operands in the data segment in all the ways we support them in the code segment. 2019-02-16 01:20:57 +00:00			`0x22/imm32 # MAP_PRIVATE \| MAP_ANONYMOUS`
4801 Reindent all SubX code to make some room for the new comment style. 2018-11-30 18:54:42 +00:00			`# fd`
4973 Support immediate operands in the data segment in all the ways we support them in the code segment. 2019-02-16 01:20:57 +00:00			`-1/imm32 # since MAP_ANONYMOUS is specified`
4801 Reindent all SubX code to make some room for the new comment style. 2018-11-30 18:54:42 +00:00			`# offset`
4973 Support immediate operands in the data segment in all the ways we support them in the code segment. 2019-02-16 01:20:57 +00:00			`0/imm32 # since MAP_ANONYMOUS is specified`
4619 - new syscall: mmap() 2018-09-29 23:17:11 +00:00
4802 Some automated commenting cleanup. Still needs more careful manual scanning. sed -i 's/^# 1-3/# . 1-3/' .subx /.subx sed -i 's/^# op/# . op/' .subx /.subx sed -i 's/# vim/# . . vim/' .subx /.subx sed -i 's/^ # push args/ # . . push args/' .subx /.subx sed -i 's/^ # discard args/ # . . discard args/' .subx /.subx sed -i 's/^ # call/ # . . call/' .subx /.subx sed -i 's/^ # prolog/ # . prolog/' .subx /.subx sed -i 's/^ # epilog/ # . epilog/' .subx /.subx sed -i 's/^ # save registers/ # . save registers/' .subx /.subx sed -i 's/^ # restore registers/ # . restore registers/' .subx /.subx sed -i 's/ operand / register /' .subx /*.subx 2018-11-30 19:10:44 +00:00			`# . . vim:nowrap:textwidth=0`