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      1 //===-- esan.cpp ----------------------------------------------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file is a part of EfficiencySanitizer, a family of performance tuners.
     11 //
     12 // Linux-specific code for the Esan run-time.
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "sanitizer_common/sanitizer_platform.h"
     16 #if SANITIZER_FREEBSD || SANITIZER_LINUX
     17 
     18 #include "esan.h"
     19 #include "esan_shadow.h"
     20 #include "interception/interception.h"
     21 #include "sanitizer_common/sanitizer_common.h"
     22 #include <sys/mman.h>
     23 #include <errno.h>
     24 
     25 namespace __esan {
     26 
     27 void verifyAddressSpace() {
     28 #if SANITIZER_LINUX && defined(__x86_64__)
     29   // The kernel determines its mmap base from the stack size limit.
     30   // Our Linux 64-bit shadow mapping assumes the stack limit is less than a
     31   // terabyte, which keeps the mmap region above 0x7e00'.
     32   uptr StackLimit = GetStackSizeLimitInBytes();
     33   if (StackSizeIsUnlimited() || StackLimit > MaxStackSize) {
     34     VReport(1, "The stack size limit is beyond the maximum supported.\n"
     35             "Re-execing with a stack size below 1TB.\n");
     36     SetStackSizeLimitInBytes(MaxStackSize);
     37     ReExec();
     38   }
     39 #endif
     40 }
     41 
     42 static bool liesWithinSingleAppRegion(uptr Start, SIZE_T Size) {
     43   uptr AppStart, AppEnd;
     44   for (int i = 0; getAppRegion(i, &AppStart, &AppEnd); ++i) {
     45     if (Start >= AppStart && Start + Size - 1 <= AppEnd) {
     46       return true;
     47     }
     48   }
     49   return false;
     50 }
     51 
     52 bool fixMmapAddr(void **Addr, SIZE_T Size, int Flags) {
     53   if (*Addr) {
     54     if (!liesWithinSingleAppRegion((uptr)*Addr, Size)) {
     55       VPrintf(1, "mmap conflict: [%p-%p) is not in an app region\n",
     56               *Addr, (uptr)*Addr + Size);
     57       if (Flags & MAP_FIXED) {
     58         errno = EINVAL;
     59         return false;
     60       } else {
     61         *Addr = 0;
     62       }
     63     }
     64   }
     65   return true;
     66 }
     67 
     68 uptr checkMmapResult(uptr Addr, SIZE_T Size) {
     69   if ((void *)Addr == MAP_FAILED)
     70     return Addr;
     71   if (!liesWithinSingleAppRegion(Addr, Size)) {
     72     // FIXME: attempt to dynamically add this as an app region if it
     73     // fits our shadow criteria.
     74     // We could also try to remap somewhere else.
     75     Printf("ERROR: unsupported mapping at [%p-%p)\n", Addr, Addr+Size);
     76     Die();
     77   }
     78   return Addr;
     79 }
     80 
     81 } // namespace __esan
     82 
     83 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX
     84