[haiku-commits] Re: BRANCH pdziepak-github.aslr - src/system/kernel/vm headers/os/kernel
- From: Axel Dörfler <axeld@xxxxxxxxxxxxxxxx>
- To: haiku-commits@xxxxxxxxxxxxx
- Date: Tue, 26 Feb 2013 15:38:08 +0100
Am 25/02/2013 23:00, schrieb pdziepak-github.aslr:
+/* http://graphics.stanford.edu/~seander/bithacks.html */
+static int
+log2(uint32_t v)
The scheduler is already using its own random function; maybe it makes
sense to put that all into some utility code.
Besides that, we keep the methods in declaration order, and keep class
methods together; IOW that helper functions should go to some place
before the class methods.
+#ifdef B_HAIKU_64_BIT
+const addr_t VMUserAddressSpace::kMaxRandomize =
0x8000000000ul;
+const addr_t VMUserAddressSpace::kMaxInitialRandomize = 0x20000000000ul;
+#else
+const addr_t VMUserAddressSpace::kMaxRandomize = 0x800000ul;
+const addr_t VMUserAddressSpace::kMaxInitialRandomize = 0x2000000ul;
+#endif
Constants and definitions go to the top of the file, not intermixed with
functions.
+addr_t
+VMUserAddressSpace::_RandomizeAddress(addr_t start, addr_t end, bool initial)
+{
+ const int rand_shift = log2(RAND_MAX) + 1;
rand_shift -> randShift. Constants usually get a 'k' prefix.
+ int shift = 0;
+
+ if (start == end)
+ return start;
That check should come first; variables should be declared immediately
before they are used.
+ random %= range;
+ random &= ~0xffful;
That looks like you wanted to write ~addr_t(B_PAGE_SIZE - 1) instead.
+ if (addressSpec == B_RAND_BASE_ADDRESS) {
+ originalStart = start;
+ start = _RandomizeAddress(start, end - size, true);
+ }
+
start = ROUNDUP(start, alignment);
I don't see where you change the size requirements of areas with a
randomized start pointer - it might need a page more.
Bye,
Axel.
Other related posts:
