[asan] Add support for Myriad RTEMS memory map

The Myriad RTEMS memory system has a few unique aspects that
require support in the ASan run-time.

- A limited amount of memory (currently 512M).

- No virtual memory, no memory protection.

- DRAM starts at address 0x80000000.  Other parts of memory may be
  used for MMIO, etc.

- The second highest address bit is the "cache" bit, and 0x80000000
  and 0x84000000 alias to the same memory.

To support the above, we make the following changes:

- Use a ShadowScale of 5, to reduce shadow memory overhead.

- Adjust some existing macros to remove assumption that the lowest
  memory address is 0.

- add a RawAddr macro that on Myriad strips the cache bit from the
  input address, before using the address for shadow memory (for other
  archs this does nothing).

- We must check that an address is in DRAM range before using it to
  index into shadow memory.

Differential Revision: https://reviews.llvm.org/D46456

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@332690 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 3 deletions

diff --git a/lib/asan/asan_poisoning.cc b/lib/asan/asan_poisoning.cc
index 62cbfe6f0..1e9c37a13 100644
--- a/lib/asan/asan_poisoning.cc
+++ b/lib/asan/asan_poisoning.cc
@@ -182,8 +182,15 @@ int __asan_address_is_poisoned(void const volatile *addr) {
 uptr __asan_region_is_poisoned(uptr beg, uptr size) {
   if (!size) return 0;
   uptr end = beg + size;
-  if (!AddrIsInMem(beg)) return beg;
-  if (!AddrIsInMem(end)) return end;
+  if (SANITIZER_MYRIAD2) {
+    // On Myriad, address not in DRAM range need to be treated as
+    // unpoisoned.
+    if (!AddrIsInMem(beg) && !AddrIsInShadow(beg)) return 0;
+    if (!AddrIsInMem(end) && !AddrIsInShadow(end)) return 0;
+  } else {
+    if (!AddrIsInMem(beg)) return beg;
+    if (!AddrIsInMem(end)) return end;
+  }
   CHECK_LT(beg, end);
   uptr aligned_b = RoundUpTo(beg, SHADOW_GRANULARITY);
   uptr aligned_e = RoundDownTo(end, SHADOW_GRANULARITY);
@@ -452,4 +459,3 @@ bool WordIsPoisoned(uptr addr) {
   return (__asan_region_is_poisoned(addr, sizeof(uptr)) != 0);
 }
 }
-