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| author | Kartik Agaram <vc@akkartik.com> | 2020-06-10 23:26:53 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2020-06-10 23:34:42 -0700 |
| commit | 80f53f4a18d3121445ee98bf405669676c5e7017 (patch) | |
| tree | d4c2a2b717c4ffc1a2da55bef334b705ba3a60b7 /059stop.subx | |
| parent | 7dac9ade153d736b7a183d073d83b7a17b22b4cc (diff) | |
| download | mu-80f53f4a18d3121445ee98bf405669676c5e7017.tar.gz | |
6508 - support null exit-descriptor
Diffstat (limited to '059stop.subx')
| -rw-r--r-- | 059stop.subx | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/059stop.subx b/059stop.subx index 85b6ad36..f6cb6fae 100644 --- a/059stop.subx +++ b/059stop.subx @@ -93,21 +93,28 @@ stop: # ed: (addr exit-descriptor), value: int # no prologue; one way or another, we're going to clobber registers # eax = ed 8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/esp 4/index/none . 0/r32/eax 4/disp8 . # copy *(esp+4) to eax + # if (ed == 0) really exit + 3d/compare-eax-and 0/imm32 + 74/jump-if-= $stop:real/disp8 # if (ed->target == 0) really exit 81 7/subop/compare 0/mod/indirect 0/rm32/eax . . . . . 0/imm32 # compare *eax - 75/jump-if-!= $stop:fake/disp8 - # . syscall(exit, value) - 8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/esp 4/index/none . 3/r32/ebx 8/disp8 . # copy *(esp+8) to ebx - e8/call syscall_exit/disp32 + 74/jump-if-= $stop:real/disp8 $stop:fake: - # otherwise: # ed->value = value+1 8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/esp 4/index/none . 1/r32/ecx 8/disp8 . # copy *(esp+8) to ecx 41/increment-ecx 89/copy 1/mod/*+disp8 0/rm32/eax . . . 1/r32/ecx 4/disp8 . # copy ecx to *(eax+4) # perform a non-local jump to ed->target 8b/copy 0/mod/indirect 0/rm32/eax . . . 4/r32/esp . . # copy *eax to esp -$stop:end: +$stop:end1: + # never gets here + c3/return # doesn't return to caller +$stop:real: + # . syscall(exit, value) + 8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/esp 4/index/none . 3/r32/ebx 8/disp8 . # copy *(esp+8) to ebx + e8/call syscall_exit/disp32 +$stop:end2: + # never gets here c3/return # doesn't return to caller test-stop-skips-returns-on-exit: |