[Mono-dev] [PATCH] more support for Google Native Client

Zoltan Varga vargaz at gmail.com
Wed Jan 5 20:19:04 EST 2011


Hi,

  This should work as follows: every aot image contains a MonoAotFileInfo
structure,
emitted in emit_file_info () in aot-compiler.c,  which has a 'flags' field,
and the MONO_AOT_FILE_FLAG_FULL_AOT flag should be set in
this field. At runtime, check_usable() in aot-runtime.c checks this flag.

                        Zoltan

On Thu, Jan 6, 2011 at 2:10 AM, Zoltan Varga <vargaz at gmail.com> wrote:

> Hi,
>
> On Thu, Jan 6, 2011 at 1:24 AM, Elijah Taylor <elijahtaylor at google.com>wrote:
>
>> Zoltan,
>>
>> I've rebased from mono's master branch and fixed all merge conflicts, but
>> something that's gone in since I first forked has now broken NaCl AOT
>> compilation for me.  On amd64 the compiler just crashes and I'm looking into
>> that, nut on x86 I'm getting this: Can't use AOT image 'mscorlib' in
>> aot-only mode because it is not compiled with --aot=full. But I'm
>> compiling with --aot=full,static,nodebug,ntrampolines=4096
>>
>> If need be I can pick through the AOT changes that have gone in, but I was
>> hoping you or someone on this list would be able to tell me the major
>> changes to AOT from the past 3 weeks and some ideas about what might be
>> getting in my way.  Can you shed any light?
>>
>>
> There was a big reorganization in the AOT file format to reduce the number
> of global symbols exported from the aot images. No idea why this is causing
> problems. make fullaotcheck and make fsacheck still seems to work for me on
> x86. I fixed a uninitilized memory error in 88d676ffd425def3, maybe that
> will help.
>
>                                     Zoltan
>
>> -Elijah
>>
>>
>>
>> On Wed, Jan 5, 2011 at 3:51 PM, Zoltan Varga <vargaz at gmail.com> wrote:
>>
>>> Hi,
>>>
>>>   I think the current code looks ok, and we should think about how to
>>> merge it into mono trunk. As a first step, could you rebase your master
>>> branch on top of master to fix the few conflicts which has surfaced due to
>>> changes to mono master ?
>>>
>>>                  Zoltan
>>>
>>> On Wed, Jan 5, 2011 at 8:23 PM, Elijah Taylor <elijahtaylor at google.com>wrote:
>>>
>>>> Hi Zoltan,
>>>>
>>>> I've addressed all of the issues you pointed out (minus genmdesc.c:
>>>> __nacl_suspend_thread_if_needed, but that doesn't need to be merged in at
>>>> this time, it can remain in my local repository only).  Please take another
>>>> look at your earliest convenience and let me know if there's anything else
>>>> you need from me.
>>>>
>>>> -Elijah
>>>>
>>>>
>>>> On Tue, Jan 4, 2011 at 10:55 AM, Elijah Taylor <elijahtaylor at google.com
>>>> > wrote:
>>>>
>>>>> Replies inline:
>>>>>
>>>>> On Tue, Jan 4, 2011 at 10:30 AM, Zoltan Varga <vargaz at gmail.com>wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>>   Some comments:
>>>>>> - the patch changes IMT_REG to AMD64_R11 in the non-nacl case, I'm not
>>>>>> sure thats
>>>>>>   intentional.
>>>>>>
>>>>>
>>>>> Has this changed in the last six months on the Mono side?  IIRC I
>>>>> didn't mean to change anything like this.  The reason I made explicit
>>>>> defines was so code in aot-compiler and mini-amd64 could share defines over
>>>>> which reg was the one we jump through and which was a scratch reg.  I'll
>>>>> diff vs Mono head revision and make it correct.
>>>>>
>>>>>
>>>>>> - you could define __mono_ilp32__ in the nacl/amd64 case, and use that
>>>>>> instead of
>>>>>>   defined(__native_client_codegen__) && defined(TARGET_AMD64) in a few
>>>>>> places.
>>>>>>
>>>>>
>>>>> That sounds reasonable.  I'm assuming you mean non-arch specific areas
>>>>> like mini.c, aot-*.c, method-to-ir.c, etc?  Are there any other major
>>>>> consequences to defining __mono_ilp32__ ?
>>>>>
>>>>>
>>>>>> - it would be better to define nacl_global_codeman_validate () as a
>>>>>> no-op in the non-nacl case, so its callers wouldn't need #ifdefs.
>>>>>>
>>>>>
>>>>> I'll fix this.
>>>>>
>>>>>
>>>>>> - genmdesc.c contains this change, which is probably not needed:
>>>>>> +void __nacl_suspend_thread_if_needed() {}
>>>>>> +
>>>>>>
>>>>>
>>>>> It is needed temporarily due to a preliminary GC implementation, we
>>>>> don't have to submit it this way.  Eventually (soon) we won't need it at
>>>>> all.
>>>>>
>>>>>
>>>>>> - you could use sizeof(mgreg_t) instead of SIZEOF_REGISTER to be
>>>>>> consistent with
>>>>>>   the usage of sizeof(gpointer).
>>>>>>
>>>>>
>>>>> Sounds good.  I'll try to use sizeof for all compiled code and only use
>>>>> SIZEOF_REGISTER/SIZEOF_VOID_P for pre-processor directives only.
>>>>>
>>>>>
>>>>>> Other than these, I think the changes look fine, they aren't that
>>>>>> disruptive, since they don't
>>>>>> change the non-nacl behavior at all.
>>>>>>
>>>>>>
>>>>> Great!  I was worried just based on LOC changed that it might get more
>>>>> resistance.  In truth I'm more worried about future Mono changes
>>>>> accidentally breaking NaCl behavior.  I'm planning on getting some automated
>>>>> testing implemented soon to combat this though.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> On Tue, Dec 21, 2010 at 9:12 PM, Elijah Taylor <
>>>>>> elijahtaylor at google.com> wrote:
>>>>>>
>>>>>>> Greetings Mono developers!
>>>>>>>
>>>>>>>
>>>>>>> *[tl;dr  very large patch for Native Client<http://www.chromium.org/nativeclient> support
>>>>>>> hosted here <https://github.com/elijahtaylor/mono>, would love
>>>>>>> feedback and many eyes to look at it]
>>>>>>> *
>>>>>>>
>>>>>>>
>>>>>>> I'm back with another round of changes for supporting Google's Native
>>>>>>> Client (NaCl), including support for amd64, JIT compilation, and Garbage
>>>>>>> Collection.  It's a large set of changes, forked on Dec 14 in github @
>>>>>>> https://github.com/elijahtaylor/mono.  I would appreciate feedback
>>>>>>> on these changes... to facilitate this, I'll try to explain the largest
>>>>>>> changes by feature (please email if clarification is needed):
>>>>>>>
>>>>>>> *1) amd64 codegen*
>>>>>>>
>>>>>>>    - Rules located here:
>>>>>>>    http://www.chromium.org/nativeclient/design-documents/nacl-sfi-model-on-x86-64-systems
>>>>>>>       - Removed %r15 from register allocation, LMF save/restore,
>>>>>>>       etc.  (r15 is special and not modifiable by untrusted code)
>>>>>>>       - Sandbox all data access through membase address mode.  If
>>>>>>>       not %rsp or %rbp relative, re-write as clearing upper 32-bits + memindex
>>>>>>>       addressing
>>>>>>>       - align functions, call sites
>>>>>>>       - Sandbox returns and all indirect jumps (need to be 32-byte
>>>>>>>       aligned, cleared upper 32-bits)
>>>>>>>       - Never omit frame pointer as general operations to rbp aren't
>>>>>>>       allowed
>>>>>>>
>>>>>>> *2) NaCl x86-64 is ILP32 (this is the largest set of changes and may
>>>>>>> make some mono devs unhappy)*
>>>>>>>
>>>>>>>    - Set SIZEOF_REGISTER == 8 while sizeof(gpointer) == 4 for NaCl
>>>>>>>    amd64 (we can use 8-byte instructions, but pointers are 4-bytes)
>>>>>>>    - Re-write large portions of mini-amd64.c, tramp-amd64.c,
>>>>>>>    exceptions-amd64.c, mini.c, method-to-ir.c to use appropriate sizes
>>>>>>>    (SIZEOF_REGISTER, sizeof(gpointer), literal '8').  *These changes
>>>>>>>    are disruptive, but ultimately they should be more correct than what was
>>>>>>>    there before.  *It's our opinion that these changes actually
>>>>>>>    improve Mono despite their impact.
>>>>>>>    - We only generate NaCl amd64 code from an ILP32 machine (either
>>>>>>>    a 32-bit application for AOT code, or NaCl runtime JIT), so we may not have
>>>>>>>    caught all of the [8 <--> SIZEOF_REGISTER] conversions, but we likely caught
>>>>>>>    most of the [sizeof(gpointer) <--> SIZEOF_REGISTER] and [8 <-->
>>>>>>>    sizeof(gpointer)] changes that are necessary.
>>>>>>>    - Change atomic operations and default pointer directives to use
>>>>>>>    32-bit instructions (long instead of quad)
>>>>>>>    - Change default operations to use 32-bit integers/pointers (eg,
>>>>>>>    OP_LOAD_MEMBASE uses 4-bytes instead of 8)
>>>>>>>
>>>>>>> *3) JIT support for NaCl*
>>>>>>>
>>>>>>>    - Since we're unable to emit code directly in its final
>>>>>>>    executable location, we instead:
>>>>>>>       - reserve a buffer on the heap
>>>>>>>       - create a hash table entry mapping the temp location and
>>>>>>>       final location
>>>>>>>       - modify all non-local patches relative to the final location
>>>>>>>       - request the NaCl runtime to install the created code in the
>>>>>>>       final location
>>>>>>>    - See mono/utils/mono-codeman.c changes for more detail.
>>>>>>>    - For every codeman *reserve*, we must add a codeman *validate*call in order to install the method/trampoline/blob in the final location
>>>>>>>    (as well as validate it for NaCl, pad it out, etc)
>>>>>>>    - We don't delete or reuse code  (we can, but it's icky and the
>>>>>>>    benefits don't outweigh the cost)
>>>>>>>    - Backpatching changed to use NaCl syscalls to modify existing
>>>>>>>    dynamic code
>>>>>>>
>>>>>>> *4) GC support for NaCl (boehm only)*
>>>>>>>
>>>>>>>    - NaCl compiler and Mono code generator both emit instrumentation
>>>>>>>    at GC "safe points" (back branches and function prologs), for cooperative
>>>>>>>    thread parking (we're not allowed to send and receive signals)
>>>>>>>    - Added new opcode OP_NACL_GC_SAFE_POINT to handle mono
>>>>>>>    instrumentation
>>>>>>>    - modified pthread_stop_world.c and pthread_support.c somewhat
>>>>>>>    extensively to support this new way of stopping the world
>>>>>>>    - wrapped pthread_exit because NaCl doesn't support pthread
>>>>>>>    cleanup functions
>>>>>>>    - added machine type NACL to libgc with machine specific defines
>>>>>>>
>>>>>>>
>>>>>>> *5) Misc bug fixes (not NaCl-specific)*
>>>>>>>
>>>>>>>    - fix *x86_memindex_emit* when disp is 32-bit
>>>>>>>    - properly exclude code in libgc/gc_dlopen.c when DYNAMIC_LOADING
>>>>>>>    not defined
>>>>>>>    - properly exclude code based on DISABLE_SOCKETS by including
>>>>>>>    config.h before checking define
>>>>>>>    - clean up calculation of offset for amd64 AOT specific
>>>>>>>    trampoline args
>>>>>>>    - fix bug in *mono_bblock_insert_before_ins* when trying to
>>>>>>>    insert an instruction to the beginning of an existing basic block.
>>>>>>>    - fix small typo bug in genmdesc.pl which kept amd64 from being
>>>>>>>    able to be a target of cross compiling
>>>>>>>    - fix struct passing in amd64 with sizeof(struct) == 16 when
>>>>>>>    fields aren't 8-byte aligned (eg, first field is 12 bytes, second field is 4
>>>>>>>    bytes), pass on stack instead of in registers (mini-amd64.c:*
>>>>>>>    add_valuetype*)
>>>>>>>    - add extra checks to mini-amd64.c:*mono_arch_emit_exceptions* to
>>>>>>>    keep exception/R4/R8 emitting from overflowing a buffer silently
>>>>>>>    - fix bugs in *new_codechunk* and *
>>>>>>>    mono_code_manager_reserve_align* which allowed unaligned code to
>>>>>>>    be allocated.
>>>>>>>
>>>>>>>
>>>>>>> I know we're close to holidays so I don't have any delusions that
>>>>>>> these changes will get in by the end of the year :)  Please feel free to
>>>>>>> pick apart these changes and let me know if there are things that should be
>>>>>>> changed.
>>>>>>>
>>>>>>> -Elijah
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Mono-devel-list mailing list
>>>>>>> Mono-devel-list at lists.ximian.com
>>>>>>> http://lists.ximian.com/mailman/listinfo/mono-devel-list
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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