[Mono-dev] [PATCH] more support for Google Native Client
Elijah Taylor
elijahtaylor at google.com
Thu Jan 6 14:14:04 EST 2011
This bit of code runs for our AOT compiler, but not for our JIT (in that
case, it's a native 32-bit app that defines __native_client_codegen__).
The problem is that chunk->data isn't guaranteed to be aligned to MIN_ALIGN
**or** the alignment you pass into *mono_code_manager_reserve_align* if you
use mono_valloc instead of dlmemalign in *new_codechunk*. But chunk->pos is
aligned to the alignment passed in, so the returned pointer could be
misaligned.
As you can see in the alloc function I adjusted it to give MIN_ALIGN - 1
extra bytes to account for this slop, and there's an identical piece to this
below for new codechunks that are allocated. I'm curious why this is
causing problems for non-nacl builds... if chunk->data is aligned this
should essentially be a no-op, and if it's not aligned, this code is
supposed to fix that. Is there a simple test I can run to see the failure?
On Thu, Jan 6, 2011 at 3:43 AM, Zoltan Varga <vargaz at gmail.com> wrote:
> Hi,
>
> I had to revert this change, as it was causing crashes on amd64:
> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
> @@ -357,8 +494,10 @@ mono_code_manager_reserve_align (MonoCodeManager
> *cman, int size, int alignment)
> for (chunk = cman->current; chunk; chunk = chunk->next) {
> if (ALIGN_INT (chunk->pos, alignment) + size <= chunk->size) {
> chunk->pos = ALIGN_INT (chunk->pos, alignment);
> - ptr = chunk->data + chunk->pos;
> - chunk->pos += size;
> + /* Align the chunk->data we add to chunk->pos */
> + /* or we can't guarantee proper alignment */
> + ptr = (void*)((((uintptr_t)chunk->data + align_mask) & ~align_mask) +
> chunk->pos);
> + chunk->pos = ((char*)ptr - chunk->data) + size;
> return ptr;
> }
> }
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>
> it was inside a #ifndef native_client, so why is this needed ?
>
> Zoltan
>
> On Thu, Jan 6, 2011 at 11:34 AM, Zoltan Varga <vargaz at gmail.com> wrote:
>
>> Hi,
>>
>> I merged your changes to mono's master except for the following:
>> runtime/mono-wrapper.in
>> mono/mini/genmdesc.c
>> nacl/
>>
>> Zoltan
>>
>>
>> On Thu, Jan 6, 2011 at 2:22 AM, Elijah Taylor <elijahtaylor at google.com>wrote:
>>
>>> Ok, I'll check out the changes/info you mentioned and go through the
>>> files that auto-merged, too. Probably won't get this done for at least a
>>> day or so, but I'll rebase again once I've fixed it. Hopefully by that
>>> point something else won't have broken too :)
>>>
>>> -Elijah
>>>
>>>
>>> On Wed, Jan 5, 2011 at 5:19 PM, Zoltan Varga <vargaz at gmail.com> wrote:
>>>
>>>> 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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