From 34c84469c23a5a0acf6f26c2c163a506d013d7ac Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Tue, 2 Oct 2018 14:33:08 -0700 Subject: 4654 --- html/subx/053new_segment.subx.html | 121 +++++++++++++++++++++++++++++++++++++ 1 file changed, 121 insertions(+) create mode 100644 html/subx/053new_segment.subx.html (limited to 'html/subx/053new_segment.subx.html') diff --git a/html/subx/053new_segment.subx.html b/html/subx/053new_segment.subx.html new file mode 100644 index 00000000..49724d37 --- /dev/null +++ b/html/subx/053new_segment.subx.html @@ -0,0 +1,121 @@ + + + + +Mu - subx/053new_segment.subx + + + + + + + + + + +
+ 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 arg
+12   68/push  0x1000/imm32
+13     # call
+14   e8/call  new_segment/disp32
+15     # discard arg
+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                         .               .             .           .             .           .           .               1/imm32/exit            # copy to EAX
+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                         .               .             .           .             .           .           .               mmap_new_segment/imm32  # copy to EBX
+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                         .               .             .           .             .           .           .               mmap_new_segment/imm32  # copy to EBX
+38   b8/copy                         .               .             .           .             .           .           .               0x5a/imm32/mmap         # copy to EAX
+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:ft=subx:nowrap:tw&
+
+ + + -- cgit 1.4.1-2-gfad0