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//===-- asan_mapping.h ------------------------------------------*- C++ -*-===//
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of AddressSanitizer, an address sanity checker.
//
// Defines ASan memory mapping.
//===----------------------------------------------------------------------===//
#ifndef ASAN_MAPPING_H
#define ASAN_MAPPING_H
#include "asan_internal.h"
// The full explanation of the memory mapping could be found here:
// http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
//
// Typical shadow mapping on Linux/x86_64 with SHADOW_OFFSET == 0x00007fff8000:
// || `[0x10007fff8000, 0x7fffffffffff]` || HighMem ||
// || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow ||
// || `[0x00008fff7000, 0x02008fff6fff]` || ShadowGap ||
// || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow ||
// || `[0x000000000000, 0x00007fff7fff]` || LowMem ||
//
// When SHADOW_OFFSET is zero (-pie):
// || `[0x100000000000, 0x7fffffffffff]` || HighMem ||
// || `[0x020000000000, 0x0fffffffffff]` || HighShadow ||
// || `[0x000000040000, 0x01ffffffffff]` || ShadowGap ||
//
// Special case when something is already mapped between
// 0x003000000000 and 0x005000000000 (e.g. when prelink is installed):
// || `[0x10007fff8000, 0x7fffffffffff]` || HighMem ||
// || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow ||
// || `[0x005000000000, 0x02008fff6fff]` || ShadowGap3 ||
// || `[0x003000000000, 0x004fffffffff]` || MidMem ||
// || `[0x000a7fff8000, 0x002fffffffff]` || ShadowGap2 ||
// || `[0x00067fff8000, 0x000a7fff7fff]` || MidShadow ||
// || `[0x00008fff7000, 0x00067fff7fff]` || ShadowGap ||
// || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow ||
// || `[0x000000000000, 0x00007fff7fff]` || LowMem ||
//
// Default Linux/i386 mapping:
// || `[0x40000000, 0xffffffff]` || HighMem ||
// || `[0x28000000, 0x3fffffff]` || HighShadow ||
// || `[0x24000000, 0x27ffffff]` || ShadowGap ||
// || `[0x20000000, 0x23ffffff]` || LowShadow ||
// || `[0x00000000, 0x1fffffff]` || LowMem ||
#if ASAN_FLEXIBLE_MAPPING_AND_OFFSET == 1
extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_offset;
# define SHADOW_SCALE (__asan_mapping_scale)
# define SHADOW_OFFSET (__asan_mapping_offset)
#else
# if ASAN_ANDROID
# define SHADOW_SCALE (3)
# define SHADOW_OFFSET (0)
# else
# define SHADOW_SCALE (3)
# if SANITIZER_WORDSIZE == 32
# define SHADOW_OFFSET (1 << 29)
# else
# if defined(__powerpc64__)
# define SHADOW_OFFSET (1ULL << 41)
# else
# if ASAN_MAC
# define SHADOW_OFFSET (1ULL << 44)
# else
# define SHADOW_OFFSET 0x7fff8000ULL
# endif
# endif
# endif
# endif
#endif // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
#define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
#define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
#define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
#define kLowMemBeg 0
#define kLowMemEnd (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
#define kLowShadowBeg SHADOW_OFFSET
#define kLowShadowEnd MEM_TO_SHADOW(kLowMemEnd)
#define kHighMemBeg (MEM_TO_SHADOW(kHighMemEnd) + 1)
#define kHighShadowBeg MEM_TO_SHADOW(kHighMemBeg)
#define kHighShadowEnd MEM_TO_SHADOW(kHighMemEnd)
# define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
# define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
// With the zero shadow base we can not actually map pages starting from 0.
// This constant is somewhat arbitrary.
#define kZeroBaseShadowStart (1 << 18)
#define kShadowGapBeg (kLowShadowEnd ? kLowShadowEnd + 1 \
: kZeroBaseShadowStart)
#define kShadowGapEnd ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
#define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
#define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
#define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
#define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
#define DO_ASAN_MAPPING_PROFILE 0 // Set to 1 to profile the functions below.
#if DO_ASAN_MAPPING_PROFILE
# define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
#else
# define PROFILE_ASAN_MAPPING()
#endif
// If 1, all shadow boundaries are constants.
// Don't set to 1 other than for testing.
#define ASAN_FIXED_MAPPING 0
namespace __asan {
extern uptr AsanMappingProfile[];
#if ASAN_FIXED_MAPPING
// Fixed mapping for 64-bit Linux. Mostly used for performance comparison
// with non-fixed mapping. As of r175253 (Feb 2013) the performance
// difference between fixed and non-fixed mapping is below the noise level.
static uptr kHighMemEnd = 0x7fffffffffffULL;
static uptr kMidMemBeg = 0x3000000000ULL;
static uptr kMidMemEnd = 0x4fffffffffULL;
#else
SANITIZER_INTERFACE_ATTRIBUTE
extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd; // Initialized in __asan_init.
#endif
static inline bool AddrIsInLowMem(uptr a) {
PROFILE_ASAN_MAPPING();
return a < kLowMemEnd;
}
static inline bool AddrIsInLowShadow(uptr a) {
PROFILE_ASAN_MAPPING();
return a >= kLowShadowBeg && a <= kLowShadowEnd;
}
static inline bool AddrIsInHighMem(uptr a) {
PROFILE_ASAN_MAPPING();
return a >= kHighMemBeg && a <= kHighMemEnd;
}
static inline bool AddrIsInMidMem(uptr a) {
PROFILE_ASAN_MAPPING();
return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
}
static inline bool AddrIsInMem(uptr a) {
PROFILE_ASAN_MAPPING();
return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
}
static inline uptr MemToShadow(uptr p) {
PROFILE_ASAN_MAPPING();
CHECK(AddrIsInMem(p));
return MEM_TO_SHADOW(p);
}
static inline bool AddrIsInHighShadow(uptr a) {
PROFILE_ASAN_MAPPING();
return a >= kHighShadowBeg && a <= kHighMemEnd;
}
static inline bool AddrIsInMidShadow(uptr a) {
PROFILE_ASAN_MAPPING();
return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
}
static inline bool AddrIsInShadow(uptr a) {
PROFILE_ASAN_MAPPING();
return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
}
static inline bool AddrIsInShadowGap(uptr a) {
PROFILE_ASAN_MAPPING();
if (kMidMemBeg) {
if (a <= kShadowGapEnd)
return SHADOW_OFFSET == 0 || a >= kShadowGapBeg;
return (a >= kShadowGap2Beg && a <= kShadowGap2End) ||
(a >= kShadowGap3Beg && a <= kShadowGap3End);
}
// In zero-based shadow mode we treat addresses near zero as addresses
// in shadow gap as well.
if (SHADOW_OFFSET == 0)
return a <= kShadowGapEnd;
return a >= kShadowGapBeg && a <= kShadowGapEnd;
}
static inline bool AddrIsAlignedByGranularity(uptr a) {
PROFILE_ASAN_MAPPING();
return (a & (SHADOW_GRANULARITY - 1)) == 0;
}
static inline bool AddressIsPoisoned(uptr a) {
PROFILE_ASAN_MAPPING();
const uptr kAccessSize = 1;
u8 *shadow_address = (u8*)MEM_TO_SHADOW(a);
s8 shadow_value = *shadow_address;
if (shadow_value) {
u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
+ kAccessSize - 1;
return (last_accessed_byte >= shadow_value);
}
return false;
}
// Must be after all calls to PROFILE_ASAN_MAPPING().
static const uptr kAsanMappingProfileSize = __LINE__;
} // namespace __asan
#endif // ASAN_MAPPING_H
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