[GHC] #7718: ios patch no 8: adjustor pools

[GHC]

#7718: ios patch no 8: adjustor pools
--------------------------------+-------------------------------------------
  Reporter:  StephenBlackheath  |          Owner:         
      Type:  feature request    |         Status:  patch  
  Priority:  normal             |      Milestone:         
 Component:  Compiler           |        Version:  7.7    
Resolution:                     |       Keywords:         
        Os:  Other              |   Architecture:  arm    
   Failure:  None/Unknown       |     Difficulty:  Unknown
  Testcase:                     |      Blockedby:         
  Blocking:  7724               |        Related:         
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Changes (by StephenBlackheath):

  * status:  new => patch


Comment:

 I have got libffi working on iOS now for adjustors, so we don't need the
 pools any more, which is great news. My work is done now (unless you need
 something fixed), and it's over to you guys.

 -----------------

 How libffi gets around Apple's restrictions is interesting, and I never
 would have thought of it. Somehow or other it manages to allocate two
 adjacent memory pages, setting the second one to be executable and putting
 some pre-compiled data in it. The executable page then fetches the
 closure's data with a PC-relative reference of -4096 or so (the page
 size), so it picks the data out of the writable memory! Mind boggling.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7718#comment:9>
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