[Mono-dev] Regression with Linux update

[Rodrigo Kumpera]

There is no plan to support W^X environments in the runtime. But if you
want to contribute code to support it, it would be welcome.


On Tue, May 22, 2012 at 10:01 PM, the mad mole <madmole at gmail.com> wrote:

> I wanted to post an update for the benefit of mono maintainers.  The
> kernel team of our SOC vendor was able to get (at least some of) the
> try-catch tests to pass (including the example below) by disabling the XI
> (execute inhibit, similar to x86 NX) feature, which was recently added to
> their MIPS core (doing some research, this appears to be part of MIPS'
> SmartMIPS ASE, which also includes a bunch of crypto functions).
>
> The speculation is that some of the jitted code is getting written to
> pages mapped with just PROT_READ | PROT_WRITE permissions: with XI enabled
> the page would need PROT_EXEC as well.  If anyone knows when this might be
> addressed, posting to this list would be much appreciated.
>
> TMM
>
> On Tue, May 15, 2012 at 6:49 PM, the mad mole <madmole at gmail.com> wrote:
>
>> I have been happily running mono 2.11.1 cross-compiled for MIPS with gcc
>> 4.5.3-1.2.  Out of nearly 500 runtime tests, only
>> async-exc-compilation.exe  and monitor.exe were failing (hangs).  Recenly
>> our SOC vendor upgraded us from 2.6.37-2.2 to -2.8, which has caused a
>> significant regression in functionality: 117 of the runtime tests now
>> fail.  It appears the culprit in many of the failures is the use of
>> try-catch.  The following simple program demonstrates the problem:
>>
>> using System;
>> namespace trycatch
>> {
>>     class MainClass
>>     {
>>         public static void Main (string[] args)
>>         {
>>             int[] array = new int[5] {10, 20, 30, 40, 50};
>>             try {
>>                 Console.WriteLine("Entering first try clause:");
>>             } catch {
>>                 Console.WriteLine("Entering first catch clause");
>>             }
>>             try {
>>                 Console.WriteLine("Entering second try clause:
>> array[5]={0}", array[5]);
>>             } catch {
>>                 Console.WriteLine("Entering second catch clause");
>>             }
>>         }
>>     }
>> }
>> Before, the expected behavior was seen:
>>
>> # mono trycatch.exe
>> Entering first try clause:
>> Entering second catch clause
>> Now, raising the exception in the second try-catch block aborts the
>> program:
>>
>> # mono trycatch.exe
>> Entering first try clause:
>> Stacktrace:
>>
>> Aborted
>> Has anyone seen behavior like this?  Any ideas where to start looking?
>>
>> TMM
>>
>>
>
>
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