diff options
| author | Kartik Agaram <vc@akkartik.com> | 2020-07-05 12:13:28 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2020-07-05 12:13:28 -0700 |
| commit | c09c91e185aad8e01b570c2569e13c1e429d2f99 (patch) | |
| tree | 52a5ae1494ad5b7b2319411815dc45510e761c24 /120allocate.subx | |
| parent | f2c5b05374186f9422cfdaf1ada096e39ac91a8b (diff) | |
| download | mu-c09c91e185aad8e01b570c2569e13c1e429d2f99.tar.gz | |
6612 - reorganize layers
Diffstat (limited to '120allocate.subx')
| -rw-r--r-- | 120allocate.subx | 953 |
1 files changed, 953 insertions, 0 deletions
diff --git a/120allocate.subx b/120allocate.subx new file mode 100644 index 00000000..4778b3ed --- /dev/null +++ b/120allocate.subx @@ -0,0 +1,953 @@ +# Helper to dynamically allocate memory on the heap. +# +# We'd like to be able to write tests for functions that allocate memory, +# making assertions on the precise addresses used. To achieve this we'll pass +# in an *allocation descriptor* to allocate from. +# +# Allocation descriptors are also useful outside of tests. Assembly and machine +# code are of necessity unsafe languages, and one of the most insidious kinds +# of bugs unsafe languages expose us to are dangling pointers to memory that +# has been freed and potentially even reused for something totally different. +# To reduce the odds of such "use after free" errors, SubX programs tend to not +# reclaim and reuse dynamically allocated memory. (Running out of memory is far +# easier to debug.) Long-running programs that want to reuse memory are mostly +# on their own to be careful. However, they do get one bit of help: they can +# carve out chunks of memory and then allocate from them manually using this +# very same 'allocate' helper. They just need a new allocation descriptor for +# their book-keeping. + +== data + +# Allocations are returned in a handle, which consists of an alloc-id and a payload. +# The alloc-id helps detect use-after-free errors. +Handle-size: # (addr int) + 8/imm32 + +# A default allocation descriptor for programs to use. +Heap: # allocation-descriptor + # curr + 0/imm32 + # limit + 0/imm32 + +# a reasonable default +Heap-size: # int + 0x600000/imm32/6MB + +Next-alloc-id: # int + 0x100/imm32 # save a few alloc ids for fake handles + +== 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 + +# Let's start initializing the default allocation descriptor. + +Entry: + # initialize heap + # . Heap = new-segment(Heap-size) + # . . push args + 68/push Heap/imm32 + ff 6/subop/push 0/mod/indirect 5/rm32/.disp32 . . . Heap-size/disp32 # push *Heap-size + # . . call + e8/call new-segment/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + + e8/call run-tests/disp32 # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'. +$array-equal-main:end: + # syscall(exit, Num-test-failures) + 8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/ebx Num-test-failures/disp32 # copy *Num-test-failures to ebx + e8/call syscall_exit/disp32 + +# Allocate and clear 'n' bytes of memory from an allocation-descriptor 'ad'. +# Abort if there isn't enough memory in 'ad'. +allocate: # ad: (addr allocation-descriptor), n: int, out: (addr handle) + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 50/push-eax + # allocate-raw(ad, n, out) + # . . push args + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x10/disp8 . # push *(ebp+16) + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12) + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) + # . . call + e8/call allocate-raw/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # eax = out->payload + 4 + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax + 8b/copy 1/mod/*+disp8 0/rm32/eax . . . 0/r32/eax 4/disp8 . # copy *(eax+4) to eax + 05/add-to-eax 4/imm32 + # zero-out(eax, n) + # . . push args + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12) + 50/push-eax + # . . call + e8/call zero-out/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp +$allocate:end: + # . restore registers + 58/pop-to-eax + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +# Claim the next 'n' bytes of memory starting at ad->curr and update ad->curr. +# Abort if there isn't enough memory in 'ad'. +allocate-raw: # ad: (addr allocation-descriptor), n: int, out: (addr handle) + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 50/push-eax + 51/push-ecx + 52/push-edx + 53/push-ebx + 56/push-esi + 57/push-edi + # ecx = ad + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 8/disp8 . # copy *(ebp+8) to ecx + # edx = out + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 2/r32/edx 0x10/disp8 . # copy *(ebp+16) to edx + # ebx = n + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 3/r32/ebx 0xc/disp8 . # copy *(ebp+12) to ebx + # out->alloc-id = Next-alloc-id + 8b/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/eax Next-alloc-id/disp32 # copy *Next-alloc-id to eax + 89/copy 0/mod/indirect 2/rm32/edx . . . 0/r32/eax . . # copy eax to *edx + # out->payload = ad->curr + 8b/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy *ecx to eax +$allocate-raw:save-payload-in-eax: + 89/copy 1/mod/*+disp8 2/rm32/edx . . . 0/r32/eax 4/disp8 . # copy eax to *(edx+4) + # *out->payload = Next-alloc-id + 8b/copy 1/mod/*+disp8 2/rm32/edx . . . 7/r32/edi 4/disp8 . # copy *(edx+4) to edi + 8b/copy 0/mod/indirect 5/rm32/.disp32 . . 6/r32/esi Next-alloc-id/disp32 # copy *Next-alloc-id to esi + 89/copy 0/mod/indirect 7/rm32/edi . . . 6/r32/esi . . # copy esi to *edi +$allocate-raw:increment-next-alloc-id: + # increment *Next-alloc-id + ff 0/subop/increment 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 # increment *Next-alloc-id + # check if there's enough space + # TODO: move this check up before any state updates when we support error recovery + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 0/base/eax 3/index/ebx . 0/r32/eax 4/disp8 . # copy eax+ebx+4 to eax + 3b/compare 1/mod/*+disp8 1/rm32/ecx . . . 0/r32/eax 4/disp8 . # compare eax with *(ecx+4) + 73/jump-if->=-signed $allocate-raw:abort/disp8 +$allocate-raw:commit: + # ad->curr += n+4 + 89/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy eax to *ecx +$allocate-raw:end: + # . restore registers + 5f/pop-to-edi + 5e/pop-to-esi + 5b/pop-to-ebx + 5a/pop-to-edx + 59/pop-to-ecx + 58/pop-to-eax + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +$allocate-raw:abort: + # . _write(2/stderr, error) + # . . push args + 68/push "allocate: failed\n"/imm32 + 68/push 2/imm32/stderr + # . . call + e8/call _write/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # . syscall(exit, 1) + bb/copy-to-ebx 1/imm32 + e8/call syscall_exit/disp32 + # never gets here + +test-allocate-raw-success: + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # var ad/ecx: allocation-descriptor + 68/push 0/imm32/limit + 68/push 0/imm32/curr + 89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx + # ad = new-segment(512) + # . . push args + 51/push-ecx + 68/push 0x200/imm32 + # . . call + e8/call new-segment/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # var expected-payload/ebx = ad->curr + 8b/copy 0/mod/indirect 1/rm32/ecx . . . 3/r32/ebx . . # copy *ecx to ebx + # var h/edx: handle = {0, 0} + 68/push 0/imm32 + 68/push 0/imm32 + 89/copy 3/mod/direct 2/rm32/edx . . . 4/r32/esp . . # copy esp to edx + # *Next-alloc-id = 0x34 + c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x34/imm32 # copy to *Next-alloc-id + # allocate-raw(ad, 3, h) + # . . push args + 52/push-edx + 68/push 3/imm32 + 51/push-ecx + # . . call + e8/call allocate-raw/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(h->alloc-id, 0x34, msg) + # . . push args + 68/push "F - test-allocate-raw-success: sets alloc-id in handle"/imm32 + 68/push 0x34/imm32 + ff 6/subop/push 0/mod/indirect 2/rm32/edx . . . . . . # push *edx + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(h->payload, expected-payload, msg) + # . . push args + 68/push "F - test-allocate-raw-success: sets payload in handle"/imm32 + 53/push-ebx + ff 6/subop/push 1/mod/*+disp8 2/rm32/edx . . . . 4/disp8 . # push *(edx+4) + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(h->payload->alloc-id, 0x34, msg) + # . . push args + 68/push "F - test-allocate-raw-success: sets alloc-id in payload"/imm32 + 68/push 0x34/imm32 + ff 6/subop/push 0/mod/indirect 3/rm32/ebx . . . . . . # push *ebx + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(*Next-alloc-id, 0x35, msg) + # . . push args + 68/push "F - test-allocate-raw-success: increments Next-alloc-id"/imm32 + 68/push 0x35/imm32 + ff 6/subop/push 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 # push *Next-alloc-id + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(ad->curr - expected-payload, 3 + 4 for alloc-id, msg) + # . . push args + 68/push "F - test-allocate-raw-success: updates allocation descriptor"/imm32 + 68/push 7/imm32 + 8b/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy *ecx to eax + 29/subtract 3/mod/direct 0/rm32/eax . . . 3/r32/ebx . . # subtract ebx from eax + 50/push-eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # clean up + c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x100/imm32 # copy to *Next-alloc-id + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +lookup: # h: (handle T) -> eax: (addr T) + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 51/push-ecx + # eax = 0 + 31/xor 3/mod/direct 0/rm32/eax . . . 0/r32/eax . . # clear eax + # ecx = handle->alloc_id + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 8/disp8 . # copy *(ebp+8) to ecx + # if (ecx == 0) return 0 + 81 7/subop/compare 3/mod/direct 1/rm32/ecx . . . . . 0/imm32 # compare ecx + 74/jump-if-= $lookup:end/disp8 + # eax = handle->address (payload) + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0xc/disp8 . # copy *(ebp+12) to eax + # if (ecx != *eax) abort + 39/compare 0/mod/indirect 0/rm32/eax . . . 1/r32/ecx . . # compare *eax and ecx + 75/jump-if-!= $lookup:abort/disp8 + # add 4 to eax + 05/add-to-eax 4/imm32 +$lookup:end: + # . restore registers + 59/pop-to-ecx + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +$lookup:abort: + # . _write(2/stderr, msg) + # . . push args + 68/push "lookup failed\n"/imm32 + 68/push 2/imm32/stderr + # . . call + e8/call _write/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # . syscall(exit, 1) + bb/copy-to-ebx 1/imm32/exit-status + e8/call syscall_exit/disp32 + +test-lookup-success: + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # var ad/ebx: allocation-descriptor + 68/push 0/imm32/limit + 68/push 0/imm32/curr + 89/copy 3/mod/direct 3/rm32/ebx . . . 4/r32/esp . . # copy esp to ebx + # ad = new-segment(512) + # . . push args + 53/push-ebx + 68/push 0x200/imm32 + # . . call + e8/call new-segment/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # var handle/ecx: handle + 68/push 0/imm32/address + 68/push 0/imm32/alloc-id + 89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx + # var old-top/edx = ad->curr + 8b/copy 0/mod/indirect 3/rm32/ebx . . . 2/r32/edx . . # copy *ebx to edx + # allocate-raw(ad, 2, handle) + # . . push args + 51/push-ecx + 68/push 2/imm32/size + 53/push-ebx + # . . call + e8/call allocate-raw/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # eax = lookup(handle) + # . . push args + ff 6/subop/push 1/mod/*+disp8 1/rm32/ecx . . . . 4/disp8 . # push *(ecx+4) + ff 6/subop/push 0/mod/indirect 1/rm32/ecx . . . . . . # push *ecx + # . . call + e8/call lookup/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # eax contains old top of heap, except skipping the alloc-id in the payload + # . check-ints-equal(eax, old-top+4, msg) + # . . push args + 68/push "F - test-lookup-success"/imm32 + 81 0/subop/add 3/mod/direct 2/rm32/edx . . . . . 4/imm32 # add to edx + 52/push-edx + 50/push-eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # clean up + c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x100/imm32 # copy to *Next-alloc-id + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +test-lookup-null-returns-null: + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # var handle/ecx: handle + 68/push 0/imm32/address + 68/push 0/imm32/alloc-id + 89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx + # eax = lookup(handle) + # . . push args + ff 6/subop/push 1/mod/*+disp8 1/rm32/ecx . . . . 4/disp8 . # push *(ecx+4) + ff 6/subop/push 0/mod/indirect 1/rm32/ecx . . . . . . # push *ecx + # . . call + e8/call lookup/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # check-ints-equal(eax, 0, msg) + # . . push args + 68/push "F - test-lookup-null-returns-null"/imm32 + 68/push 0/imm32 + 50/push-eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +_pending-test-lookup-failure: + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # var heap/esi: allocation-descriptor + 68/push 0/imm32/limit + 68/push 0/imm32/curr + 89/copy 3/mod/direct 6/rm32/esi . . . 4/r32/esp . . # copy esp to esi + # heap = new-segment(512) + # . . push args + 56/push-esi + 68/push 0x200/imm32 + # . . call + e8/call new-segment/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # var h1/ecx: handle + 68/push 0/imm32/address + 68/push 0/imm32/alloc-id + 89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx + # var old_top/ebx = heap->curr + 8b/copy 0/mod/indirect 6/rm32/esi . . . 3/r32/ebx . . # copy *esi to ebx + # first allocation, to h1 + # . allocate(heap, 2, h1) + # . . push args + 51/push-ecx + 68/push 2/imm32/size + 56/push-esi + # . . call + e8/call allocate/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # reset heap->curr to mimic reclamation + 89/copy 0/mod/indirect 6/rm32/esi . . . 3/r32/ebx . . # copy ebx to *esi + # second allocation that returns the same address as the first + # var h2/edx: handle + 68/push 0/imm32/address + 68/push 0/imm32/alloc-id + 89/copy 3/mod/direct 2/rm32/edx . . . 4/r32/esp . . # copy esp to edx + # . allocate(heap, 2, h2) + # . . push args + 52/push-edx + 68/push 2/imm32/size + 56/push-esi + # . . call + e8/call allocate/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(h1->address, h2->address, msg) + # . . push args + 68/push "F - test-lookup-failure"/imm32 + ff 6/subop/push 1/mod/*+disp8 2/rm32/ecx . . . . 4/disp8 . # push *(edx+4) + ff 6/subop/push 1/mod/*+disp8 1/rm32/ecx . . . . 4/disp8 . # push *(ecx+4) + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # lookup(h1) should crash + # . . push args + ff 6/subop/push 1/mod/*+disp8 1/rm32/ecx . . . . 4/disp8 . # push *(ecx+4) + ff 6/subop/push 0/mod/indirect 1/rm32/ecx . . . . . . # push *ecx + # . . call + e8/call lookup/disp32 + # should never get past this point + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # clean up + c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x100/imm32 # copy to *Next-alloc-id + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +# when comparing handles, just treat them as pure values +handle-equal?: # a: handle, b: handle -> eax: boolean + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 51/push-ecx + # eax = false + b8/copy-to-eax 0/imm32/false +$handle-equal?:compare-alloc-id: + # ecx = a->alloc_id + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 8/disp8 . # copy *(ebp+8) to ecx + # if (ecx != b->alloc_id) return false + 39/compare 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0x10/disp8 . # compare ecx and *(ebp+16) + 75/jump-if-!= $handle-equal?:end/disp8 +$handle-equal?:compare-address: + # ecx = handle->address + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0xc/disp8 . # copy *(ebp+12) to ecx + # if (ecx != b->address) return false + 39/compare 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0x14/disp8 . # compare ecx and *(ebp+20) + 75/jump-if-!= $handle-equal?:end/disp8 +$handle-equal?:return-true: + # return true + b8/copy-to-eax 1/imm32/true +$handle-equal?:end: + # . restore registers + 59/pop-to-ecx + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +copy-handle: # src: handle, dest: (addr handle) + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 50/push-eax + 51/push-ecx + # ecx = dest + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0x10/disp8 . # copy *(ebp+16) to ecx + # *dest = src + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 8/disp8 . # copy *(ebp+8) to eax + 89/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy eax to *ecx + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0xc/disp8 . # copy *(ebp+12) to eax + 89/copy 1/mod/*+disp8 1/rm32/ecx . . . 0/r32/eax 4/disp8 . # copy eax to *(ecx+4) +$copy-handle:end: + # . restore registers + 59/pop-to-ecx + 58/pop-to-eax + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +# helper: create a nested allocation descriptor (useful for tests) +allocate-region: # ad: (addr allocation-descriptor), n: int, out: (addr handle allocation-descriptor) + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 50/push-eax + 51/push-ecx + # allocate(ad, n, out) + # . . push args + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x10/disp8 . # push *(ebp+16) + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12) + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) + # . . call + e8/call allocate/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # eax = out->payload + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax + 8b/copy 1/mod/*+disp8 0/rm32/eax . . . 0/r32/eax 4/disp8 . # copy *(eax+4) to eax + # skip payload->allocid + 05/add-to-eax 4/imm32 + # if (eax == 0) abort + 3d/compare-eax-and 0/imm32 + 74/jump-if-= $allocate-region:abort/disp8 + # earmark 8 bytes at the start for a new allocation descriptor + # . *eax = eax + 8 + 89/copy 3/mod/direct 1/rm32/ecx . . . 0/r32/eax . . # copy eax to ecx + 81 0/subop/add 3/mod/direct 1/rm32/ecx . . . . . 8/imm32 # add to ecx + 89/copy 0/mod/indirect 0/rm32/eax . . . 1/r32/ecx . . # copy ecx to *eax + # . *(eax+4) = eax + n + 89/copy 3/mod/direct 1/rm32/ecx . . . 0/r32/eax . . # copy eax to ecx + 03/add 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0xc/disp8 . # add *(ebp+12) to ecx + 89/copy 1/mod/*+disp8 0/rm32/eax . . . 1/r32/ecx 4/disp8 . # copy ecx to *(eax+4) + # . restore registers + 59/pop-to-ecx + 58/pop-to-eax + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +# We could create a more general '$abort' jump target, but then we'd need to do +# a conditional jump followed by loading the error message and an unconditional +# jump. Or we'd need to unconditionally load the error message before a +# conditional jump, even if it's unused the vast majority of the time. This way +# we bloat a potentially cold segment in RAM so we can abort with a single +# instruction. +$allocate-region:abort: + # . _write(2/stderr, error) + # . . push args + 68/push "allocate-region: failed to allocate\n"/imm32 + 68/push 2/imm32/stderr + # . . call + e8/call _write/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # . syscall(exit, 1) + bb/copy-to-ebx 1/imm32 + e8/call syscall_exit/disp32 + # never gets here + +# Claim the next 'n+4' bytes of memory and initialize the first 4 to n. +# Abort if there isn't enough memory in 'ad'. +allocate-array: # ad: (addr allocation-descriptor), n: int, out: (addr handle) + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 50/push-eax + 51/push-ecx + 52/push-edx + # ecx = n + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0xc/disp8 . # copy *(ebp+12) to ecx + # var size/edx: int = n+4 + 8d/copy-address 1/mod/*+disp8 1/rm32/ecx . . . 2/r32/edx 4/disp8 . # copy ecx+4 to edx + # allocate(ad, size, out) + # . . push args + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x10/disp8 . # push *(ebp+16) + 52/push-edx + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) + # . . call + e8/call allocate/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # *out->payload = n + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax + 8b/copy 1/mod/*+disp8 0/rm32/eax . . . 0/r32/eax 4/disp8 . # copy *(eax+4) to eax + # . skip payload->allocid + 05/add-to-eax 4/imm32 + # . + 89/copy 0/mod/indirect 0/rm32/eax . . . 1/r32/ecx . . # copy ecx to *eax +$allocate-array:end: + # . restore registers + 5a/pop-to-edx + 59/pop-to-ecx + 58/pop-to-eax + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +test-allocate-array: + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # var ad/ecx: allocation-descriptor + 68/push 0/imm32/limit + 68/push 0/imm32/curr + 89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx + # ad = new-segment(512) + # . . push args + 51/push-ecx + 68/push 0x200/imm32 + # . . call + e8/call new-segment/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # var expected-payload/ebx = ad->curr + 8b/copy 0/mod/indirect 1/rm32/ecx . . . 3/r32/ebx . . # copy *ecx to ebx + # var h/edx: handle = {0, 0} + 68/push 0/imm32 + 68/push 0/imm32 + 89/copy 3/mod/direct 2/rm32/edx . . . 4/r32/esp . . # copy esp to edx + # *Next-alloc-id = 0x34 + c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x34/imm32 # copy to *Next-alloc-id + # allocate-array(ad, 3, h) + # . . push args + 52/push-edx + 68/push 3/imm32 + 51/push-ecx + # . . call + e8/call allocate-array/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(h->alloc-id, 0x34, msg) + # . . push args + 68/push "F - test-allocate-array: sets alloc-id in handle"/imm32 + 68/push 0x34/imm32 + ff 6/subop/push 0/mod/indirect 2/rm32/edx . . . . . . # push *edx + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(h->payload, expected-payload, msg) + # . . push args + 68/push "F - test-allocate-array: sets payload in handle"/imm32 + 53/push-ebx + ff 6/subop/push 1/mod/*+disp8 2/rm32/edx . . . . 4/disp8 . # push *(edx+4) + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(h->payload->alloc-id, 0x34, msg) + # . . push args + 68/push "F - test-allocate-array: sets alloc-id in payload"/imm32 + 68/push 0x34/imm32 + ff 6/subop/push 0/mod/indirect 3/rm32/ebx . . . . . . # push *ebx + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(h->payload->size, 3, msg) + # . . push args + 68/push "F - test-allocate-array: sets array size in payload"/imm32 + 68/push 3/imm32 + ff 6/subop/push 1/mod/*+disp8 3/rm32/ebx . . . . 4/disp8 . # push *(ebx+4) + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(*Next-alloc-id, 0x35, msg) + # . . push args + 68/push "F - test-allocate-array: increments Next-alloc-id"/imm32 + 68/push 0x35/imm32 + ff 6/subop/push 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 # push *Next-alloc-id + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(ad->curr - expected-payload, 3 + 4 for alloc-id + 4 for array size, msg) + # . . push args + 68/push "F - test-allocate-array: updates allocation descriptor"/imm32 + 68/push 0xb/imm32 + 8b/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy *ecx to eax + 29/subtract 3/mod/direct 0/rm32/eax . . . 3/r32/ebx . . # subtract ebx from eax + 50/push-eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # clean up + c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 1/imm32 # copy to *Next-alloc-id + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +copy-array: # ad: (addr allocation-descriptor), src: (addr array), out: (addr handle) + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 50/push-eax + 51/push-ecx + 52/push-edx + 56/push-esi + # esi = src + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 0xc/disp8 . # copy *(ebp+12) to esi + # var size/ecx: int = src->size+4 + 8b/copy 0/mod/indirect 6/rm32/esi . . . 1/r32/ecx . . # copy *esi to ecx + 81 0/subop/add 3/mod/direct 1/rm32/ecx . . . . . 4/imm32 # add to ecx + # allocate(ad, size, out) + # . . push args + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x10/disp8 . # push *(ebp+16) + 51/push-ecx + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) + # . . call + e8/call allocate/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # var payload/eax: (addr byte) = out->payload + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax + 8b/copy 1/mod/*+disp8 0/rm32/eax . . . 0/r32/eax 4/disp8 . # copy *(eax+4) to eax + # . skip payload->allocid + 05/add-to-eax 4/imm32 + # var max/ecx: (addr byte) = payload + size + 01/add 3/mod/direct 1/rm32/ecx . . . 0/r32/eax . . # add eax to ecx + # _append-4(payload, max, src, &src->data[src->size]) + # . . push &src->data[src->size] + 8b/copy 0/mod/indirect 6/rm32/esi . . . 2/r32/edx . . # copy *esi to edx + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 6/base/esi 2/index/edx . 2/r32/edx 4/disp8 . # copy esi+edx+4 to edx + 52/push-edx + # . . push src + 56/push-esi + # . . push max + 51/push-ecx + # . . push payload + 50/push-eax + # . . call + e8/call _append-4/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x10/imm32 # add to esp +$copy-array:end: + # . restore registers + 5e/pop-to-esi + 5a/pop-to-edx + 59/pop-to-ecx + 58/pop-to-eax + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +test-copy-array: + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # var src/esi: (addr array int) = [3, 4, 5] + 68/push 5/imm32 + 68/push 4/imm32 + 68/push 3/imm32 + 68/push 0xc/imm32/size + 89/copy 3/mod/direct 6/rm32/esi . . . 4/r32/esp . . # copy esp to esi + # var ad/ecx: allocation-descriptor + 68/push 0/imm32/limit + 68/push 0/imm32/curr + 89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx + # ad = new-segment(512) + # . . push args + 51/push-ecx + 68/push 0x200/imm32 + # . . call + e8/call new-segment/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # var expected-payload/ebx = ad->curr + 8b/copy 0/mod/indirect 1/rm32/ecx . . . 3/r32/ebx . . # copy *ecx to ebx + # var h/edx: handle = {0, 0} + 68/push 0/imm32 + 68/push 0/imm32 + 89/copy 3/mod/direct 2/rm32/edx . . . 4/r32/esp . . # copy esp to edx + # *Next-alloc-id = 0x34 + c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x34/imm32 # copy to *Next-alloc-id + # copy-array(ad, src, h) + # . . push args + 52/push-edx + 56/push-esi + 51/push-ecx + # . . call + e8/call copy-array/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(h->alloc-id, 0x34, msg) + # . . push args + 68/push "F - test-copy-array: sets alloc-id in handle"/imm32 + 68/push 0x34/imm32 + ff 6/subop/push 0/mod/indirect 2/rm32/edx . . . . . . # push *edx + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(h->payload, expected-payload, msg) + # . . push args + 68/push "F - test-copy-array: sets payload in handle"/imm32 + 53/push-ebx + ff 6/subop/push 1/mod/*+disp8 2/rm32/edx . . . . 4/disp8 . # push *(edx+4) + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(h->payload->alloc-id, 0x34, msg) + # . . push args + 68/push "F - test-copy-array: sets alloc-id in payload"/imm32 + 68/push 0x34/imm32 + ff 6/subop/push 0/mod/indirect 2/rm32/edx . . . . . . # push *edx + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # var payload/eax: (addr int) = lookup(h) + # . . push args + ff 6/subop/push 1/mod/*+disp8 2/rm32/edx . . . . 4/disp8 . # push *(edx+4) + ff 6/subop/push 0/mod/indirect 2/rm32/edx . . . . . . # push *edx + # . . call + e8/call lookup/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # check-ints-equal(payload->size, 0xc, msg) + # . . push args + 68/push "F - test-copy-array: sets array size in payload"/imm32 + 68/push 0xc/imm32 + ff 6/subop/push 0/mod/indirect 0/rm32/eax . . . . . . # push *eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(*Next-alloc-id, 0x35, msg) + # . . push args + 68/push "F - test-copy-array: increments Next-alloc-id"/imm32 + 68/push 0x35/imm32 + ff 6/subop/push 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 # push *Next-alloc-id + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(ad->curr - expected-payload, 12 + 4 for alloc-id + 4 for length, msg) + # . . push args + 68/push "F - test-copy-array: updates allocation descriptor"/imm32 + 68/push 0x14/imm32 + 8b/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy *ecx to eax + 29/subtract 3/mod/direct 0/rm32/eax . . . 3/r32/ebx . . # subtract ebx from eax + 50/push-eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # clean up + c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 1/imm32 # copy to *Next-alloc-id + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +# Fill a region of memory with zeroes. +zero-out: # start: (addr byte), len: int + # pseudocode: + # curr/esi = start + # i/ecx = 0 + # while true + # if (i >= len) break + # *curr = 0 + # ++curr + # ++i + # + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 50/push-eax + 51/push-ecx + 52/push-edx + 56/push-esi + # curr/esi = start + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 8/disp8 . # copy *(ebp+8) to esi + # var i/ecx: int = 0 + 31/xor 3/mod/direct 1/rm32/ecx . . . 1/r32/ecx . . # clear ecx + # edx = len + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 2/r32/edx 0xc/disp8 . # copy *(ebp+12) to edx +$zero-out:loop: + # if (i >= len) break + 39/compare 3/mod/direct 1/rm32/ecx . . . 2/r32/edx . . # compare ecx with edx + 7d/jump-if->= $zero-out:end/disp8 + # *curr = 0 + c6 0/subop/copy 0/mod/direct 6/rm32/esi . . . . . 0/imm8 # copy byte to *esi + # ++curr + 46/increment-esi + # ++i + 41/increment-ecx + eb/jump $zero-out:loop/disp8 +$zero-out:end: + # . restore registers + 5e/pop-to-esi + 5a/pop-to-edx + 59/pop-to-ecx + 58/pop-to-eax + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +test-zero-out: + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # region/ecx = 34, 35, 36, 37 + 68/push 0x37363534/imm32 + 89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx + # zero-out(ecx, 3) + # . . push args + 68/push 3/imm32/len + 51/push-ecx + # . . call + e8/call zero-out/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # first 3 bytes cleared, fourth left alone + # . check-ints-equal(*ecx, 0x37000000, msg) + # . . push args + 68/push "F - test-zero-out"/imm32 + 68/push 0x37000000/imm32 + ff 6/subop/push 0/mod/indirect 1/rm32/ecx . . . . . . # push *ecx + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +# . . vim:nowrap:textwidth=0 |