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

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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
This commit is contained in:
Nick Kralevich 2010-05-06 15:05:52 -07:00
parent 4e226a5006
commit beeeee705b
2 changed files with 33 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

34
libpixelflinger/codeflinger/CodeCache.cpp
View file

@ -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) {
mSize = size;
}
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)

6
libpixelflinger/codeflinger/CodeCache.h
View file

@ -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;
};
// ----------------------------------------------------------------------------