Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit beeeee70 authored by Nick Kralevich's avatar Nick Kralevich
Browse files

Allow pixelflinger to work when NX (No Execute) is enabled. 

Instead of allocating memory from the (non executable) heap,
allocate memory using mspace and ensure that we use mprotect
to mark it as PROT_EXEC.  This allows pixelflinger to
continue to work even when NX protections are enabled.

Testing: Using the ApiDemos market app, verify that
Apidemos -> Graphics -> OpenGL ES -> GLSurfaceView
works when "adb shell setprop debug.egl.hw 0" is set.

Change-Id: Ib569cd2543c6fa25688ee76325a712bc2347450b
parent 4e226a50

libpixelflinger/codeflinger/CodeCache.cpp

+28 −6
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ 
#include <assert.h>

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/mman.h>



#include <cutils/log.h>

#include <cutils/atomic.h>
@@ -39,15 +41,14 @@ namespace android { 
Assembly::Assembly(size_t size)

    : mCount(1), mSize(0)

{

    mBase = (uint32_t*)malloc(size);

    if (mBase) {

    mBase = (uint32_t*)mspace_malloc(getMspace(), size);

    mSize = size;

    }

    ensureMbaseExecutable();

}



Assembly::~Assembly()

{

    free(mBase);

    mspace_free(getMspace(), mBase);

}



void Assembly::incStrong(const void*) const
@@ -75,11 +76,32 @@ uint32_t* Assembly::base() const 


ssize_t Assembly::resize(size_t newSize)

{

    mBase = (uint32_t*)realloc(mBase, newSize);

    mBase = (uint32_t*)mspace_realloc(getMspace(), mBase, newSize);

    mSize = newSize;

    ensureMbaseExecutable();

    return size();

}



mspace Assembly::getMspace()

{

    static mspace msp = create_contiguous_mspace(2 * 1024, 1024 * 1024, /*locked=*/ false);

    return msp;

}



void Assembly::ensureMbaseExecutable()

{

    long pagesize = sysconf(_SC_PAGESIZE);

    long pagemask = ~(pagesize - 1);  // assumes pagesize is a power of 2



    uint32_t* pageStart = (uint32_t*) (((uintptr_t) mBase) & pagemask);

    size_t adjustedLength = mBase - pageStart + mSize;



    if (mBase && mprotect(pageStart, adjustedLength, PROT_READ | PROT_WRITE | PROT_EXEC) != 0) {

        mspace_free(getMspace(), mBase);

        mBase = NULL;

    }

}



// ----------------------------------------------------------------------------



CodeCache::CodeCache(size_t size)

libpixelflinger/codeflinger/CodeCache.h

+5 −1
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <stdint.h>

#include <pthread.h>

#include <sys/types.h>

#include <cutils/mspace.h>



#include "tinyutils/KeyedVector.h"

#include "tinyutils/smartpointer.h"
@@ -67,9 +68,12 @@ public: 
    typedef void    weakref_type;



private:

    static  mspace  getMspace();

            void    ensureMbaseExecutable();



    mutable int32_t     mCount;

            uint32_t*   mBase;

            ssize_t     mSize;

            size_t      mSize;

};



// ----------------------------------------------------------------------------