[compiler-rt] r204897 - [asan] Do not sanitize kernel area on 32-bit targets, patch by Yuri Gribov

[Kostya Serebryany]

FYI
I had to disable this code in r207768 as it misbehaves under schroot,
we'll need more robust way to check that the upper 1G is not available in
user space.

--kcc


On Thu, Mar 27, 2014 at 11:36 AM, Kostya Serebryany <kcc at google.com> wrote:

> Author: kcc
> Date: Thu Mar 27 02:36:26 2014
> New Revision: 204897
>
> URL: http://llvm.org/viewvc/llvm-project?rev=204897&view=rev
> Log:
> [asan] Do not sanitize kernel area on 32-bit targets, patch by Yuri Gribov
>
> Modified:
>     compiler-rt/trunk/lib/asan/asan_mapping.h
>     compiler-rt/trunk/lib/asan/asan_rtl.cc
>     compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.cc
>     compiler-rt/trunk/test/asan/lit.cfg
>
> Modified: compiler-rt/trunk/lib/asan/asan_mapping.h
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_mapping.h?rev=204897&r1=204896&r2=204897&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/lib/asan/asan_mapping.h (original)
> +++ compiler-rt/trunk/lib/asan/asan_mapping.h Thu Mar 27 02:36:26 2014
> @@ -43,13 +43,22 @@
>  // || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow  ||
>  // || `[0x000000000000, 0x00007fff7fff]` || LowMem     ||
>  //
> -// Default Linux/i386 mapping:
> +// Default Linux/i386 mapping on x86_64 machine:
>  // || `[0x40000000, 0xffffffff]` || HighMem    ||
>  // || `[0x28000000, 0x3fffffff]` || HighShadow ||
>  // || `[0x24000000, 0x27ffffff]` || ShadowGap  ||
>  // || `[0x20000000, 0x23ffffff]` || LowShadow  ||
>  // || `[0x00000000, 0x1fffffff]` || LowMem     ||
>  //
> +// Default Linux/i386 mapping on i386 machine
> +// (addresses starting with 0xc0000000 are reserved
> +// for kernel and thus not sanitized):
> +// || `[0x38000000, 0xbfffffff]` || HighMem    ||
> +// || `[0x27000000, 0x37ffffff]` || HighShadow ||
> +// || `[0x24000000, 0x26ffffff]` || ShadowGap  ||
> +// || `[0x20000000, 0x23ffffff]` || LowShadow  ||
> +// || `[0x00000000, 0x1fffffff]` || LowMem     ||
> +//
>  // Default Linux/MIPS mapping:
>  // || `[0x2aaa8000, 0xffffffff]` || HighMem    ||
>  // || `[0x0fffd000, 0x2aaa7fff]` || HighShadow ||
>
> Modified: compiler-rt/trunk/lib/asan/asan_rtl.cc
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_rtl.cc?rev=204897&r1=204896&r2=204897&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/lib/asan/asan_rtl.cc (original)
> +++ compiler-rt/trunk/lib/asan/asan_rtl.cc Thu Mar 27 02:36:26 2014
> @@ -565,6 +565,7 @@ static void AsanInitInternal() {
>      ReserveShadowMemoryRange(kHighShadowBeg, kHighShadowEnd);
>      // protect the gap.
>      ProtectGap(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
> +    CHECK_EQ(kShadowGapEnd, kHighShadowBeg - 1);
>    } else if (kMidMemBeg &&
>        MemoryRangeIsAvailable(shadow_start, kMidMemBeg - 1) &&
>        MemoryRangeIsAvailable(kMidMemEnd + 1, kHighShadowEnd)) {
>
> Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.cc
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.cc?rev=204897&r1=204896&r2=204897&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.cc (original)
> +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.cc Thu Mar 27
> 02:36:26 2014
> @@ -22,6 +22,10 @@
>
>  #include <sys/mman.h>
>
> +#if SANITIZER_LINUX
> +#include <sys/utsname.h>
> +#endif
> +
>  namespace __sanitizer {
>
>  // ------------- sanitizer_common.h
> @@ -29,6 +33,21 @@ uptr GetMmapGranularity() {
>    return GetPageSize();
>  }
>
> +#if SANITIZER_WORDSIZE == 32
> +// Take care of unusable kernel area in top gigabyte
> +static uptr GetKernelStartAddress() {
> +#if SANITIZER_LINUX
> +  // 64-bit Linux provides 32-bit apps with full address space
> +  struct utsname uname_info;
> +  return 0 == uname(&uname_info) && !internal_strstr(uname_info.machine,
> "64")
> +    ? 1ULL << 30
> +    : 0;
> +#else
> +  return 0;
> +#endif  // SANITIZER_LINUX
> +}
> +#endif  // SANITIZER_WORDSIZE == 32
> +
>  uptr GetMaxVirtualAddress() {
>  #if SANITIZER_WORDSIZE == 64
>  # if defined(__powerpc64__)
> @@ -44,8 +63,10 @@ uptr GetMaxVirtualAddress() {
>    return (1ULL << 47) - 1;  // 0x00007fffffffffffUL;
>  # endif
>  #else  // SANITIZER_WORDSIZE == 32
> -  // FIXME: We can probably lower this on Android?
> -  return (1ULL << 32) - 1;  // 0xffffffff;
> +  uptr res = (1ULL << 32) - 1;  // 0xffffffff;
> +  res -= GetKernelStartAddress();
> +  CHECK_LT(reinterpret_cast<uptr>(&res), res);
> +  return res;
>  #endif  // SANITIZER_WORDSIZE
>  }
>
>
> Modified: compiler-rt/trunk/test/asan/lit.cfg
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/lit.cfg?rev=204897&r1=204896&r2=204897&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/test/asan/lit.cfg (original)
> +++ compiler-rt/trunk/test/asan/lit.cfg Thu Mar 27 02:36:26 2014
> @@ -60,8 +60,15 @@ if not os.path.exists(asan_symbolize):
>  python_exec = get_required_attr(config, "python_executable")
>  config.substitutions.append( ("%asan_symbolize", python_exec + " " +
> asan_symbolize + " ") )
>
> +# Determine kernel bitness
> +if config.host_arch.find('64') != -1 and config.android != "TRUE":
> +  kernel_bits = '64'
> +else:
> +  kernel_bits = '32'
> +
>  # Define CHECK-%os to check for OS-dependent output.
>  config.substitutions.append( ('CHECK-%os', ("CHECK-" + config.host_os)))
> +config.substitutions.append( ('CHECK-%kernel_bits', ("CHECK-kernel-" +
> kernel_bits + "-bits")))
>
>  config.available_features.add("asan-" + config.bits + "-bits")
>
>
>
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