cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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entropy_common.c (13551B)

      1/* ******************************************************************
      2 * Common functions of New Generation Entropy library
      3 * Copyright (c) Yann Collet, Facebook, Inc.
      4 *
      5 *  You can contact the author at :
      6 *  - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy
      7 *  - Public forum : https://groups.google.com/forum/#!forum/lz4c
      8 *
      9 * This source code is licensed under both the BSD-style license (found in the
     10 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
     11 * in the COPYING file in the root directory of this source tree).
     12 * You may select, at your option, one of the above-listed licenses.
     13****************************************************************** */
     14
     15/* *************************************
     16*  Dependencies
     17***************************************/
     18#include "mem.h"
     19#include "error_private.h"       /* ERR_*, ERROR */
     20#define FSE_STATIC_LINKING_ONLY  /* FSE_MIN_TABLELOG */
     21#include "fse.h"
     22#define HUF_STATIC_LINKING_ONLY  /* HUF_TABLELOG_ABSOLUTEMAX */
     23#include "huf.h"
     24
     25
     26/*===   Version   ===*/
     27unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; }
     28
     29
     30/*===   Error Management   ===*/
     31unsigned FSE_isError(size_t code) { return ERR_isError(code); }
     32const char* FSE_getErrorName(size_t code) { return ERR_getErrorName(code); }
     33
     34unsigned HUF_isError(size_t code) { return ERR_isError(code); }
     35const char* HUF_getErrorName(size_t code) { return ERR_getErrorName(code); }
     36
     37
     38/*-**************************************************************
     39*  FSE NCount encoding-decoding
     40****************************************************************/
     41static U32 FSE_ctz(U32 val)
     42{
     43    assert(val != 0);
     44    {
     45#   if (__GNUC__ >= 3)   /* GCC Intrinsic */
     46        return __builtin_ctz(val);
     47#   else   /* Software version */
     48        U32 count = 0;
     49        while ((val & 1) == 0) {
     50            val >>= 1;
     51            ++count;
     52        }
     53        return count;
     54#   endif
     55    }
     56}
     57
     58FORCE_INLINE_TEMPLATE
     59size_t FSE_readNCount_body(short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
     60                           const void* headerBuffer, size_t hbSize)
     61{
     62    const BYTE* const istart = (const BYTE*) headerBuffer;
     63    const BYTE* const iend = istart + hbSize;
     64    const BYTE* ip = istart;
     65    int nbBits;
     66    int remaining;
     67    int threshold;
     68    U32 bitStream;
     69    int bitCount;
     70    unsigned charnum = 0;
     71    unsigned const maxSV1 = *maxSVPtr + 1;
     72    int previous0 = 0;
     73
     74    if (hbSize < 8) {
     75        /* This function only works when hbSize >= 8 */
     76        char buffer[8] = {0};
     77        ZSTD_memcpy(buffer, headerBuffer, hbSize);
     78        {   size_t const countSize = FSE_readNCount(normalizedCounter, maxSVPtr, tableLogPtr,
     79                                                    buffer, sizeof(buffer));
     80            if (FSE_isError(countSize)) return countSize;
     81            if (countSize > hbSize) return ERROR(corruption_detected);
     82            return countSize;
     83    }   }
     84    assert(hbSize >= 8);
     85
     86    /* init */
     87    ZSTD_memset(normalizedCounter, 0, (*maxSVPtr+1) * sizeof(normalizedCounter[0]));   /* all symbols not present in NCount have a frequency of 0 */
     88    bitStream = MEM_readLE32(ip);
     89    nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG;   /* extract tableLog */
     90    if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge);
     91    bitStream >>= 4;
     92    bitCount = 4;
     93    *tableLogPtr = nbBits;
     94    remaining = (1<<nbBits)+1;
     95    threshold = 1<<nbBits;
     96    nbBits++;
     97
     98    for (;;) {
     99        if (previous0) {
    100            /* Count the number of repeats. Each time the
    101             * 2-bit repeat code is 0b11 there is another
    102             * repeat.
    103             * Avoid UB by setting the high bit to 1.
    104             */
    105            int repeats = FSE_ctz(~bitStream | 0x80000000) >> 1;
    106            while (repeats >= 12) {
    107                charnum += 3 * 12;
    108                if (LIKELY(ip <= iend-7)) {
    109                    ip += 3;
    110                } else {
    111                    bitCount -= (int)(8 * (iend - 7 - ip));
    112                    bitCount &= 31;
    113                    ip = iend - 4;
    114                }
    115                bitStream = MEM_readLE32(ip) >> bitCount;
    116                repeats = FSE_ctz(~bitStream | 0x80000000) >> 1;
    117            }
    118            charnum += 3 * repeats;
    119            bitStream >>= 2 * repeats;
    120            bitCount += 2 * repeats;
    121
    122            /* Add the final repeat which isn't 0b11. */
    123            assert((bitStream & 3) < 3);
    124            charnum += bitStream & 3;
    125            bitCount += 2;
    126
    127            /* This is an error, but break and return an error
    128             * at the end, because returning out of a loop makes
    129             * it harder for the compiler to optimize.
    130             */
    131            if (charnum >= maxSV1) break;
    132
    133            /* We don't need to set the normalized count to 0
    134             * because we already memset the whole buffer to 0.
    135             */
    136
    137            if (LIKELY(ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
    138                assert((bitCount >> 3) <= 3); /* For first condition to work */
    139                ip += bitCount>>3;
    140                bitCount &= 7;
    141            } else {
    142                bitCount -= (int)(8 * (iend - 4 - ip));
    143                bitCount &= 31;
    144                ip = iend - 4;
    145            }
    146            bitStream = MEM_readLE32(ip) >> bitCount;
    147        }
    148        {
    149            int const max = (2*threshold-1) - remaining;
    150            int count;
    151
    152            if ((bitStream & (threshold-1)) < (U32)max) {
    153                count = bitStream & (threshold-1);
    154                bitCount += nbBits-1;
    155            } else {
    156                count = bitStream & (2*threshold-1);
    157                if (count >= threshold) count -= max;
    158                bitCount += nbBits;
    159            }
    160
    161            count--;   /* extra accuracy */
    162            /* When it matters (small blocks), this is a
    163             * predictable branch, because we don't use -1.
    164             */
    165            if (count >= 0) {
    166                remaining -= count;
    167            } else {
    168                assert(count == -1);
    169                remaining += count;
    170            }
    171            normalizedCounter[charnum++] = (short)count;
    172            previous0 = !count;
    173
    174            assert(threshold > 1);
    175            if (remaining < threshold) {
    176                /* This branch can be folded into the
    177                 * threshold update condition because we
    178                 * know that threshold > 1.
    179                 */
    180                if (remaining <= 1) break;
    181                nbBits = BIT_highbit32(remaining) + 1;
    182                threshold = 1 << (nbBits - 1);
    183            }
    184            if (charnum >= maxSV1) break;
    185
    186            if (LIKELY(ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
    187                ip += bitCount>>3;
    188                bitCount &= 7;
    189            } else {
    190                bitCount -= (int)(8 * (iend - 4 - ip));
    191                bitCount &= 31;
    192                ip = iend - 4;
    193            }
    194            bitStream = MEM_readLE32(ip) >> bitCount;
    195    }   }
    196    if (remaining != 1) return ERROR(corruption_detected);
    197    /* Only possible when there are too many zeros. */
    198    if (charnum > maxSV1) return ERROR(maxSymbolValue_tooSmall);
    199    if (bitCount > 32) return ERROR(corruption_detected);
    200    *maxSVPtr = charnum-1;
    201
    202    ip += (bitCount+7)>>3;
    203    return ip-istart;
    204}
    205
    206/* Avoids the FORCE_INLINE of the _body() function. */
    207static size_t FSE_readNCount_body_default(
    208        short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
    209        const void* headerBuffer, size_t hbSize)
    210{
    211    return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
    212}
    213
    214#if DYNAMIC_BMI2
    215TARGET_ATTRIBUTE("bmi2") static size_t FSE_readNCount_body_bmi2(
    216        short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
    217        const void* headerBuffer, size_t hbSize)
    218{
    219    return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
    220}
    221#endif
    222
    223size_t FSE_readNCount_bmi2(
    224        short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
    225        const void* headerBuffer, size_t hbSize, int bmi2)
    226{
    227#if DYNAMIC_BMI2
    228    if (bmi2) {
    229        return FSE_readNCount_body_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
    230    }
    231#endif
    232    (void)bmi2;
    233    return FSE_readNCount_body_default(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
    234}
    235
    236size_t FSE_readNCount(
    237        short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
    238        const void* headerBuffer, size_t hbSize)
    239{
    240    return FSE_readNCount_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize, /* bmi2 */ 0);
    241}
    242
    243
    244/*! HUF_readStats() :
    245    Read compact Huffman tree, saved by HUF_writeCTable().
    246    `huffWeight` is destination buffer.
    247    `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32.
    248    @return : size read from `src` , or an error Code .
    249    Note : Needed by HUF_readCTable() and HUF_readDTableX?() .
    250*/
    251size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats,
    252                     U32* nbSymbolsPtr, U32* tableLogPtr,
    253                     const void* src, size_t srcSize)
    254{
    255    U32 wksp[HUF_READ_STATS_WORKSPACE_SIZE_U32];
    256    return HUF_readStats_wksp(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, wksp, sizeof(wksp), /* bmi2 */ 0);
    257}
    258
    259FORCE_INLINE_TEMPLATE size_t
    260HUF_readStats_body(BYTE* huffWeight, size_t hwSize, U32* rankStats,
    261                   U32* nbSymbolsPtr, U32* tableLogPtr,
    262                   const void* src, size_t srcSize,
    263                   void* workSpace, size_t wkspSize,
    264                   int bmi2)
    265{
    266    U32 weightTotal;
    267    const BYTE* ip = (const BYTE*) src;
    268    size_t iSize;
    269    size_t oSize;
    270
    271    if (!srcSize) return ERROR(srcSize_wrong);
    272    iSize = ip[0];
    273    /* ZSTD_memset(huffWeight, 0, hwSize);   *//* is not necessary, even though some analyzer complain ... */
    274
    275    if (iSize >= 128) {  /* special header */
    276        oSize = iSize - 127;
    277        iSize = ((oSize+1)/2);
    278        if (iSize+1 > srcSize) return ERROR(srcSize_wrong);
    279        if (oSize >= hwSize) return ERROR(corruption_detected);
    280        ip += 1;
    281        {   U32 n;
    282            for (n=0; n<oSize; n+=2) {
    283                huffWeight[n]   = ip[n/2] >> 4;
    284                huffWeight[n+1] = ip[n/2] & 15;
    285    }   }   }
    286    else  {   /* header compressed with FSE (normal case) */
    287        if (iSize+1 > srcSize) return ERROR(srcSize_wrong);
    288        /* max (hwSize-1) values decoded, as last one is implied */
    289        oSize = FSE_decompress_wksp_bmi2(huffWeight, hwSize-1, ip+1, iSize, 6, workSpace, wkspSize, bmi2);
    290        if (FSE_isError(oSize)) return oSize;
    291    }
    292
    293    /* collect weight stats */
    294    ZSTD_memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32));
    295    weightTotal = 0;
    296    {   U32 n; for (n=0; n<oSize; n++) {
    297            if (huffWeight[n] >= HUF_TABLELOG_MAX) return ERROR(corruption_detected);
    298            rankStats[huffWeight[n]]++;
    299            weightTotal += (1 << huffWeight[n]) >> 1;
    300    }   }
    301    if (weightTotal == 0) return ERROR(corruption_detected);
    302
    303    /* get last non-null symbol weight (implied, total must be 2^n) */
    304    {   U32 const tableLog = BIT_highbit32(weightTotal) + 1;
    305        if (tableLog > HUF_TABLELOG_MAX) return ERROR(corruption_detected);
    306        *tableLogPtr = tableLog;
    307        /* determine last weight */
    308        {   U32 const total = 1 << tableLog;
    309            U32 const rest = total - weightTotal;
    310            U32 const verif = 1 << BIT_highbit32(rest);
    311            U32 const lastWeight = BIT_highbit32(rest) + 1;
    312            if (verif != rest) return ERROR(corruption_detected);    /* last value must be a clean power of 2 */
    313            huffWeight[oSize] = (BYTE)lastWeight;
    314            rankStats[lastWeight]++;
    315    }   }
    316
    317    /* check tree construction validity */
    318    if ((rankStats[1] < 2) || (rankStats[1] & 1)) return ERROR(corruption_detected);   /* by construction : at least 2 elts of rank 1, must be even */
    319
    320    /* results */
    321    *nbSymbolsPtr = (U32)(oSize+1);
    322    return iSize+1;
    323}
    324
    325/* Avoids the FORCE_INLINE of the _body() function. */
    326static size_t HUF_readStats_body_default(BYTE* huffWeight, size_t hwSize, U32* rankStats,
    327                     U32* nbSymbolsPtr, U32* tableLogPtr,
    328                     const void* src, size_t srcSize,
    329                     void* workSpace, size_t wkspSize)
    330{
    331    return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 0);
    332}
    333
    334#if DYNAMIC_BMI2
    335static TARGET_ATTRIBUTE("bmi2") size_t HUF_readStats_body_bmi2(BYTE* huffWeight, size_t hwSize, U32* rankStats,
    336                     U32* nbSymbolsPtr, U32* tableLogPtr,
    337                     const void* src, size_t srcSize,
    338                     void* workSpace, size_t wkspSize)
    339{
    340    return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 1);
    341}
    342#endif
    343
    344size_t HUF_readStats_wksp(BYTE* huffWeight, size_t hwSize, U32* rankStats,
    345                     U32* nbSymbolsPtr, U32* tableLogPtr,
    346                     const void* src, size_t srcSize,
    347                     void* workSpace, size_t wkspSize,
    348                     int bmi2)
    349{
    350#if DYNAMIC_BMI2
    351    if (bmi2) {
    352        return HUF_readStats_body_bmi2(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize);
    353    }
    354#endif
    355    (void)bmi2;
    356    return HUF_readStats_body_default(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize);
    357}