[compiler-rt] r282405 - tsan: make shadow mapping linear within a single user region

[Dmitry Vyukov via llvm-commits]

Author: dvyukov
Date: Mon Sep 26 08:41:33 2016
New Revision: 282405

URL: http://llvm.org/viewvc/llvm-project?rev=282405&view=rev
Log:
tsan: make shadow mapping linear within a single user region

This is a follow up to r282152.
A more extensive testing on real apps revealed a subtle bug in r282152.
The revision made shadow mapping non-linear even within a single
user region. But there are lots of code in runtime that processes
memory ranges and assumes that mapping is linear. For example,
region memory access handling simply increments shadow address
to advance to the next shadow cell group. Similarly, DontNeedShadowFor,
java memory mover, search of heap memory block header, etc
make similar assumptions.
To trigger the bug user range would need to cross 0x008000000000 boundary.
This was observed for a module data section.

Make shadow mapping linear within a single user range again.
Add a startup CHECK for linearity.


Modified:
    compiler-rt/trunk/lib/tsan/rtl/tsan_platform.h
    compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.cc

Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_platform.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_platform.h?rev=282405&r1=282404&r2=282405&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_platform.h (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_platform.h Mon Sep 26 08:41:33 2016
@@ -29,37 +29,37 @@ namespace __tsan {
 #if defined(__x86_64__)
 /*
 C/C++ on linux/x86_64 and freebsd/x86_64
-0000 0000 1000 - 0040 0000 0000: main binary and/or MAP_32BIT mappings (256GB)
+0000 0000 1000 - 0080 0000 0000: main binary and/or MAP_32BIT mappings (512GB)
 0040 0000 0000 - 0100 0000 0000: -
-0100 0000 0000 - 1000 0000 0000: shadow
-1000 0000 0000 - 3000 0000 0000: -
+0100 0000 0000 - 2000 0000 0000: shadow
+2000 0000 0000 - 3000 0000 0000: -
 3000 0000 0000 - 4000 0000 0000: metainfo (memory blocks and sync objects)
-4000 0000 0000 - 5540 0000 0000: -
-5540 0000 0000 - 5680 0000 0000: pie binaries without ASLR or on 4.1+ kernels
+4000 0000 0000 - 5500 0000 0000: -
+5500 0000 0000 - 5680 0000 0000: pie binaries without ASLR or on 4.1+ kernels
 5680 0000 0000 - 6000 0000 0000: -
 6000 0000 0000 - 6200 0000 0000: traces
 6200 0000 0000 - 7d00 0000 0000: -
-7c40 0000 0000 - 7d40 0000 0000: heap
-7d40 0000 0000 - 7ec0 0000 0000: -
-7ec0 0000 0000 - 8000 0000 0000: modules and main thread stack
+7b00 0000 0000 - 7c00 0000 0000: heap
+7c00 0000 0000 - 7e80 0000 0000: -
+7e80 0000 0000 - 8000 0000 0000: modules and main thread stack
 */
 struct Mapping {
   static const uptr kMetaShadowBeg = 0x300000000000ull;
-  static const uptr kMetaShadowEnd = 0x400000000000ull;
+  static const uptr kMetaShadowEnd = 0x340000000000ull;
   static const uptr kTraceMemBeg   = 0x600000000000ull;
   static const uptr kTraceMemEnd   = 0x620000000000ull;
   static const uptr kShadowBeg     = 0x010000000000ull;
-  static const uptr kShadowEnd     = 0x100000000000ull;
-  static const uptr kHeapMemBeg    = 0x7c4000000000ull;
-  static const uptr kHeapMemEnd    = 0x7d4000000000ull;
+  static const uptr kShadowEnd     = 0x200000000000ull;
+  static const uptr kHeapMemBeg    = 0x7b0000000000ull;
+  static const uptr kHeapMemEnd    = 0x7c0000000000ull;
   static const uptr kLoAppMemBeg   = 0x000000001000ull;
-  static const uptr kLoAppMemEnd   = 0x004000000000ull;
-  static const uptr kMidAppMemBeg  = 0x554000000000ull;
+  static const uptr kLoAppMemEnd   = 0x008000000000ull;
+  static const uptr kMidAppMemBeg  = 0x550000000000ull;
   static const uptr kMidAppMemEnd  = 0x568000000000ull;
-  static const uptr kHiAppMemBeg   = 0x7ec000000000ull;
+  static const uptr kHiAppMemBeg   = 0x7e8000000000ull;
   static const uptr kHiAppMemEnd   = 0x800000000000ull;
-  static const uptr kAppMemMsk     = 0x7c0000000000ull;
-  static const uptr kAppMemXor     = 0x028000000000ull;
+  static const uptr kAppMemMsk     = 0x780000000000ull;
+  static const uptr kAppMemXor     = 0x040000000000ull;
   static const uptr kVdsoBeg       = 0xf000000000000000ull;
 };
 

Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.cc?rev=282405&r1=282404&r2=282405&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.cc (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.cc Mon Sep 26 08:41:33 2016
@@ -292,9 +292,11 @@ static void CheckShadowMapping() {
     if (beg ==end)
       continue;
     VPrintf(3, "checking shadow region %p-%p\n", beg, end);
+    uptr prev = 0;
     for (uptr p0 = beg; p0 <= end; p0 += (end - beg) / 4) {
-      for (int x = -1; x <= 1; x++) {
+      for (int x = -(int)kShadowCell; x <= (int)kShadowCell; x += kShadowCell) {
         const uptr p = p0 + x;
+        CHECK_EQ(p, RoundDown(p, kShadowCell));
         if (p < beg || p >= end)
           continue;
         const uptr s = MemToShadow(p);
@@ -302,8 +304,18 @@ static void CheckShadowMapping() {
         VPrintf(3, "  checking pointer %p: shadow=%p meta=%p\n", p, s, m);
         CHECK(IsAppMem(p));
         CHECK(IsShadowMem(s));
-        CHECK_EQ(p & ~(kShadowCell - 1), ShadowToMem(s));
+        CHECK_EQ(p, ShadowToMem(s));
         CHECK(IsMetaMem(m));
+        if (prev) {
+          // Ensure that shadow and meta mappings are linear within a single
+          // user range. Lots of code that processes memory ranges assumes it.
+          const uptr prev_s = MemToShadow(prev);
+          const uptr prev_m = (uptr)MemToMeta(prev);
+          CHECK_EQ(s - prev_s, (p - prev) * kShadowMultiplier);
+          CHECK_EQ((m - prev_m) / kMetaShadowSize,
+                   (p - prev) / kMetaShadowCell);
+        }
+        prev = p;
       }
     }
   }