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vm: implement B_RANDOMIZED_ANY_ADDRESS address specification

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Randomized equivalent of B_ANY_ADDRESS. When a free space is found (as in
B_ANY_ADDRESS) the base adress is then randomized using _RandomizeAddress
pretty much like it is done in B_RANDOMIZED_BASE_ADDRESS.
This commit is contained in:
Pawel Dziepak 2013-02-27 01:32:09 +01:00
parent f9bab525f6
commit b3e4c67739
4 changed files with 66 additions and 18 deletions
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2
headers/os/kernel/OS.h
View File

@ -79,7 +79,7 @@ typedef struct area_info {
#define B_CLONE_ADDRESS 3
#define B_ANY_KERNEL_ADDRESS 4
/* B_ANY_KERNEL_BLOCK_ADDRESS 5 */
/* B_RANDOMIZED_ANY_ADDRESS 6 */
#define B_RANDOMIZED_ANY_ADDRESS 6
#define B_RANDOMIZED_BASE_ADDRESS 7
/* area protection */

79
src/system/kernel/vm/VMUserAddressSpace.cpp
View File

@ -174,6 +174,7 @@ VMUserAddressSpace::InsertArea(VMArea* _area, size_t size,
case B_ANY_ADDRESS:
case B_ANY_KERNEL_ADDRESS:
case B_ANY_KERNEL_BLOCK_ADDRESS:
case B_RANDOMIZED_ANY_ADDRESS:
searchBase = fBase;
// TODO: remove this again when vm86 mode is moved into the kernel
// completely (currently needs a userland address space!)
@ -402,8 +403,11 @@ VMUserAddressSpace::Dump() const
addr_t
VMUserAddressSpace::_RandomizeAddress(addr_t start, addr_t end, bool initial)
VMUserAddressSpace::_RandomizeAddress(addr_t start, addr_t end,
size_t alignment, bool initial)
{
ASSERT((start & addr_t(alignment - 1)) == 0);
if (start == end)
return start;
@ -430,7 +434,7 @@ VMUserAddressSpace::_RandomizeAddress(addr_t start, addr_t end, bool initial)
range = min_c(range, kMaxRandomize);
random %= range;
random &= ~addr_t(B_PAGE_SIZE - 1);
random &= ~addr_t(alignment - 1);
return start + random;
}
@ -555,13 +559,13 @@ VMUserAddressSpace::_InsertAreaSlot(addr_t start, addr_t size, addr_t end,
alignment <<= 1;
}
if (addressSpec == B_RANDOMIZED_BASE_ADDRESS) {
originalStart = start;
start = _RandomizeAddress(start, end - size, true);
}
start = ROUNDUP(start, alignment);
if (addressSpec == B_RANDOMIZED_BASE_ADDRESS) {
originalStart = start;
start = _RandomizeAddress(start, end - size, alignment, true);
}
// walk up to the spot where we should start searching
second_chance:
VMUserAreaList::Iterator it = fAreas.GetIterator();
@ -581,13 +585,20 @@ second_chance:
case B_ANY_ADDRESS:
case B_ANY_KERNEL_ADDRESS:
case B_ANY_KERNEL_BLOCK_ADDRESS:
case B_RANDOMIZED_ANY_ADDRESS:
{
// find a hole big enough for a new area
if (last == NULL) {
// see if we can build it at the beginning of the virtual map
addr_t alignedBase = ROUNDUP(start, alignment);
if (is_valid_spot(start, alignedBase, size,
next == NULL ? end : next->Base())) {
addr_t nextBase = next == NULL ? end : next->Base();
if (is_valid_spot(start, alignedBase, size, nextBase)) {
if (addressSpec == B_RANDOMIZED_ANY_ADDRESS) {
alignedBase = _RandomizeAddress(alignedBase,
nextBase - size, alignment);
}
foundSpot = true;
area->SetBase(alignedBase);
break;
@ -603,6 +614,12 @@ second_chance:
alignment);
if (is_valid_spot(last->Base() + (last->Size() - 1),
alignedBase, size, next->Base())) {
if (addressSpec == B_RANDOMIZED_ANY_ADDRESS) {
alignedBase = _RandomizeAddress(alignedBase,
next->Base() - size, alignment);
}
foundSpot = true;
area->SetBase(alignedBase);
break;
@ -619,6 +636,12 @@ second_chance:
alignment);
if (is_valid_spot(last->Base() + (last->Size() - 1), alignedBase,
size, end)) {
if (addressSpec == B_RANDOMIZED_ANY_ADDRESS) {
alignedBase = _RandomizeAddress(alignedBase, end - size,
alignment);
}
// got a spot
foundSpot = true;
area->SetBase(alignedBase);
@ -653,12 +676,19 @@ second_chance:
if ((next->protection & RESERVED_AVOID_BASE) == 0
&& alignedBase == next->Base()
&& next->Size() >= size) {
if (addressSpec == B_RANDOMIZED_ANY_ADDRESS) {
alignedBase = _RandomizeAddress(next->Base(),
next->Size() - size, alignment);
}
addr_t offset = alignedBase - next->Base();
// The new area will be placed at the beginning of the
// reserved area and the reserved area will be offset
// and resized
foundSpot = true;
next->SetBase(next->Base() + size);
next->SetSize(next->Size() - size);
next->SetBase(next->Base() + offset + size);
next->SetSize(next->Size() - offset - size);
area->SetBase(alignedBase);
break;
}
@ -668,8 +698,23 @@ second_chance:
// The new area will be placed at the end of the
// reserved area, and the reserved area will be resized
// to make space
alignedBase = ROUNDDOWN(
next->Base() + next->Size() - size, alignment);
if (addressSpec == B_RANDOMIZED_ANY_ADDRESS) {
addr_t alignedNextBase = ROUNDUP(next->Base(),
alignment);
addr_t startRange = next->Base() + next->Size();
startRange -= size + kMaxRandomize;
startRange = ROUNDDOWN(startRange, alignment);
startRange = max_c(startRange, alignedNextBase);
alignedBase = _RandomizeAddress(startRange,
next->Base() + next->Size() - size, alignment);
} else {
alignedBase = ROUNDDOWN(
next->Base() + next->Size() - size, alignment);
}
foundSpot = true;
next->SetSize(alignedBase - next->Base());
@ -726,7 +771,7 @@ second_chance:
spaceEnd = next->Base();
start = _RandomizeAddress(lastEnd + 1, spaceEnd - size,
false);
B_PAGE_SIZE);
}
area->SetBase(start);
@ -736,10 +781,12 @@ second_chance:
// we didn't find a free spot in the requested range, so we'll
// try again without any restrictions
if (addressSpec != B_RANDOMIZED_BASE_ADDRESS
|| originalStart == 0) {
if (addressSpec != B_RANDOMIZED_BASE_ADDRESS) {
start = fBase;
addressSpec = B_ANY_ADDRESS;
} else if (originalStart == 0) {
start = fBase;
addressSpec = B_RANDOMIZED_ANY_ADDRESS;
} else {
start = originalStart;
originalStart = 0;

2
src/system/kernel/vm/VMUserAddressSpace.h
View File

@ -54,7 +54,7 @@ public:
private:
static addr_t _RandomizeAddress(addr_t start, addr_t end,
bool initial);
size_t alignment, bool initial = false);
status_t _InsertAreaIntoReservedRegion(addr_t start,
size_t size, VMUserArea* area,

1
src/system/kernel/vm/vm.cpp
View File

@ -1219,6 +1219,7 @@ vm_create_anonymous_area(team_id team, const char *name, addr_t size,
case B_BASE_ADDRESS:
case B_ANY_KERNEL_ADDRESS:
case B_ANY_KERNEL_BLOCK_ADDRESS:
case B_RANDOMIZED_ANY_ADDRESS:
case B_RANDOMIZED_BASE_ADDRESS:
break;