src/cpu/ppc/vm/vm_version_ppc.cpp

Tue, 18 Jun 2019 09:33:34 -0400

author
ogatak
date
Tue, 18 Jun 2019 09:33:34 -0400
changeset 9713
c4567d28f31f
parent 9684
69f33959c27f
child 9730
42118db355f5
permissions
-rw-r--r--

8185979: PPC64: Implement SHA2 intrinsic
Reviewed-by: mdoerr, goetz
Contributed-by: Bruno Rosa <bruno.rosa@eldorado.org.br>, Gustavo Serra Scalet <gustavo.scalet@eldorado.org.br>, Igor Nunes <igor.nunes@eldorado.org.br>, Martin Doerr <martin.doerr@sap.com>

     1 /*
     2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
     3  * Copyright 2012, 2018 SAP AG. All rights reserved.
     4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     5  *
     6  * This code is free software; you can redistribute it and/or modify it
     7  * under the terms of the GNU General Public License version 2 only, as
     8  * published by the Free Software Foundation.
     9  *
    10  * This code is distributed in the hope that it will be useful, but WITHOUT
    11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    13  * version 2 for more details (a copy is included in the LICENSE file that
    14  * accompanied this code).
    15  *
    16  * You should have received a copy of the GNU General Public License version
    17  * 2 along with this work; if not, write to the Free Software Foundation,
    18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
    19  *
    20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
    21  * or visit www.oracle.com if you need additional information or have any
    22  * questions.
    23  *
    24  */
    26 #include "precompiled.hpp"
    27 #include "asm/assembler.inline.hpp"
    28 #include "asm/macroAssembler.inline.hpp"
    29 #include "compiler/disassembler.hpp"
    30 #include "memory/resourceArea.hpp"
    31 #include "runtime/java.hpp"
    32 #include "runtime/stubCodeGenerator.hpp"
    33 #include "utilities/defaultStream.hpp"
    34 #include "vm_version_ppc.hpp"
    35 #ifdef TARGET_OS_FAMILY_aix
    36 # include "os_aix.inline.hpp"
    37 #endif
    38 #ifdef TARGET_OS_FAMILY_linux
    39 # include "os_linux.inline.hpp"
    40 #endif
    42 # include <sys/sysinfo.h>
    44 int VM_Version::_features = VM_Version::unknown_m;
    45 int VM_Version::_measured_cache_line_size = 128; // default value
    46 const char* VM_Version::_features_str = "";
    47 bool VM_Version::_is_determine_features_test_running = false;
    48 uint64_t VM_Version::_dscr_val = 0;
    50 #define MSG(flag)   \
    51   if (flag && !FLAG_IS_DEFAULT(flag))                                  \
    52       jio_fprintf(defaultStream::error_stream(),                       \
    53                   "warning: -XX:+" #flag " requires -XX:+UseSIGTRAP\n" \
    54                   "         -XX:+" #flag " will be disabled!\n");
    56 void VM_Version::initialize() {
    58   // Test which instructions are supported and measure cache line size.
    59   determine_features();
    61   // If PowerArchitecturePPC64 hasn't been specified explicitly determine from features.
    62   if (FLAG_IS_DEFAULT(PowerArchitecturePPC64)) {
    63     if (VM_Version::has_lqarx()) {
    64       FLAG_SET_ERGO(uintx, PowerArchitecturePPC64, 8);
    65     } else if (VM_Version::has_popcntw()) {
    66       FLAG_SET_ERGO(uintx, PowerArchitecturePPC64, 7);
    67     } else if (VM_Version::has_cmpb()) {
    68       FLAG_SET_ERGO(uintx, PowerArchitecturePPC64, 6);
    69     } else if (VM_Version::has_popcntb()) {
    70       FLAG_SET_ERGO(uintx, PowerArchitecturePPC64, 5);
    71     } else {
    72       FLAG_SET_ERGO(uintx, PowerArchitecturePPC64, 0);
    73     }
    74   }
    75   guarantee(PowerArchitecturePPC64 == 0 || PowerArchitecturePPC64 == 5 ||
    76             PowerArchitecturePPC64 == 6 || PowerArchitecturePPC64 == 7 ||
    77             PowerArchitecturePPC64 == 8,
    78             "PowerArchitecturePPC64 should be 0, 5, 6, 7, or 8");
    80   // Power 8: Configure Data Stream Control Register.
    81   if (PowerArchitecturePPC64 >= 8) {
    82     config_dscr();
    83   }
    85   if (!UseSIGTRAP) {
    86     MSG(TrapBasedICMissChecks);
    87     MSG(TrapBasedNotEntrantChecks);
    88     MSG(TrapBasedNullChecks);
    89     FLAG_SET_ERGO(bool, TrapBasedNotEntrantChecks, false);
    90     FLAG_SET_ERGO(bool, TrapBasedNullChecks,       false);
    91     FLAG_SET_ERGO(bool, TrapBasedICMissChecks,     false);
    92   }
    94 #ifdef COMPILER2
    95   if (!UseSIGTRAP) {
    96     MSG(TrapBasedRangeChecks);
    97     FLAG_SET_ERGO(bool, TrapBasedRangeChecks, false);
    98   }
   100   // On Power6 test for section size.
   101   if (PowerArchitecturePPC64 == 6) {
   102     determine_section_size();
   103   // TODO: PPC port } else {
   104   // TODO: PPC port PdScheduling::power6SectorSize = 0x20;
   105   }
   107   MaxVectorSize = 8;
   108 #endif
   110   // Create and print feature-string.
   111   char buf[(num_features+1) * 16]; // Max 16 chars per feature.
   112   jio_snprintf(buf, sizeof(buf),
   113                "ppc64%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
   114                (has_fsqrt()   ? " fsqrt"   : ""),
   115                (has_isel()    ? " isel"    : ""),
   116                (has_lxarxeh() ? " lxarxeh" : ""),
   117                (has_cmpb()    ? " cmpb"    : ""),
   118                //(has_mftgpr()? " mftgpr"  : ""),
   119                (has_popcntb() ? " popcntb" : ""),
   120                (has_popcntw() ? " popcntw" : ""),
   121                (has_fcfids()  ? " fcfids"  : ""),
   122                (has_vand()    ? " vand"    : ""),
   123                (has_lqarx()   ? " lqarx"   : ""),
   124                (has_vcipher() ? " aes"     : ""),
   125                (has_vpmsumb() ? " vpmsumb" : ""),
   126                (has_mfdscr()  ? " mfdscr"  : ""),
   127                (has_vsx()     ? " vsx"     : ""),
   128                (has_vshasig() ? " sha"     : "")
   129                // Make sure number of %s matches num_features!
   130               );
   131   _features_str = strdup(buf);
   132   if (Verbose) {
   133     print_features();
   134   }
   136   // PPC64 supports 8-byte compare-exchange operations (see
   137   // Atomic::cmpxchg and StubGenerator::generate_atomic_cmpxchg_ptr)
   138   // and 'atomic long memory ops' (see Unsafe_GetLongVolatile).
   139   _supports_cx8 = true;
   141   UseSSE = 0; // Only on x86 and x64
   143   intx cache_line_size = _measured_cache_line_size;
   145   if (FLAG_IS_DEFAULT(AllocatePrefetchStyle)) AllocatePrefetchStyle = 1;
   147   if (AllocatePrefetchStyle == 4) {
   148     AllocatePrefetchStepSize = cache_line_size; // Need exact value.
   149     if (FLAG_IS_DEFAULT(AllocatePrefetchLines)) AllocatePrefetchLines = 12; // Use larger blocks by default.
   150     if (AllocatePrefetchDistance < 0) AllocatePrefetchDistance = 2*cache_line_size; // Default is not defined?
   151   } else {
   152     if (cache_line_size > AllocatePrefetchStepSize) AllocatePrefetchStepSize = cache_line_size;
   153     if (FLAG_IS_DEFAULT(AllocatePrefetchLines)) AllocatePrefetchLines = 3; // Optimistic value.
   154     if (AllocatePrefetchDistance < 0) AllocatePrefetchDistance = 3*cache_line_size; // Default is not defined?
   155   }
   157   assert(AllocatePrefetchLines > 0, "invalid value");
   158   if (AllocatePrefetchLines < 1) { // Set valid value in product VM.
   159     AllocatePrefetchLines = 1; // Conservative value.
   160   }
   162   if (AllocatePrefetchStyle == 3 && AllocatePrefetchDistance < cache_line_size) {
   163     AllocatePrefetchStyle = 1; // Fall back if inappropriate.
   164   }
   166   assert(AllocatePrefetchStyle >= 0, "AllocatePrefetchStyle should be positive");
   168   // Implementation does not use any of the vector instructions
   169   // available with Power8. Their exploitation is still pending.
   170   if (!UseCRC32Intrinsics) {
   171     if (FLAG_IS_DEFAULT(UseCRC32Intrinsics)) {
   172       FLAG_SET_DEFAULT(UseCRC32Intrinsics, true);
   173     }
   174   }
   176   // The AES intrinsic stubs require AES instruction support.
   177 #if defined(VM_LITTLE_ENDIAN)
   178   if (has_vcipher()) {
   179     if (FLAG_IS_DEFAULT(UseAES)) {
   180       UseAES = true;
   181     }
   182   } else if (UseAES) {
   183     if (!FLAG_IS_DEFAULT(UseAES))
   184       warning("AES instructions are not available on this CPU");
   185     FLAG_SET_DEFAULT(UseAES, false);
   186   }
   188   if (UseAES && has_vcipher()) {
   189     if (FLAG_IS_DEFAULT(UseAESIntrinsics)) {
   190       UseAESIntrinsics = true;
   191     }
   192   } else if (UseAESIntrinsics) {
   193     if (!FLAG_IS_DEFAULT(UseAESIntrinsics))
   194       warning("AES intrinsics are not available on this CPU");
   195     FLAG_SET_DEFAULT(UseAESIntrinsics, false);
   196   }
   198 #else
   199   if (UseAES) {
   200     warning("AES instructions are not available on this CPU");
   201     FLAG_SET_DEFAULT(UseAES, false);
   202   }
   203   if (UseAESIntrinsics) {
   204     if (!FLAG_IS_DEFAULT(UseAESIntrinsics))
   205       warning("AES intrinsics are not available on this CPU");
   206     FLAG_SET_DEFAULT(UseAESIntrinsics, false);
   207   }
   208 #endif
   210   if (has_vshasig()) {
   211     if (FLAG_IS_DEFAULT(UseSHA)) {
   212       UseSHA = true;
   213     }
   214   } else if (UseSHA) {
   215     if (!FLAG_IS_DEFAULT(UseSHA))
   216       warning("SHA instructions are not available on this CPU");
   217     FLAG_SET_DEFAULT(UseSHA, false);
   218   }
   220   if (UseSHA1Intrinsics) {
   221     warning("Intrinsics for SHA-1 crypto hash functions not available on this CPU.");
   222     FLAG_SET_DEFAULT(UseSHA1Intrinsics, false);
   223   }
   225   if (UseSHA && has_vshasig()) {
   226     if (FLAG_IS_DEFAULT(UseSHA256Intrinsics)) {
   227       FLAG_SET_DEFAULT(UseSHA256Intrinsics, true);
   228     }
   229   } else if (UseSHA256Intrinsics) {
   230     warning("Intrinsics for SHA-224 and SHA-256 crypto hash functions not available on this CPU.");
   231     FLAG_SET_DEFAULT(UseSHA256Intrinsics, false);
   232   }
   234   if (UseSHA && has_vshasig()) {
   235     if (FLAG_IS_DEFAULT(UseSHA512Intrinsics)) {
   236       FLAG_SET_DEFAULT(UseSHA512Intrinsics, true);
   237     }
   238   } else if (UseSHA512Intrinsics) {
   239     warning("Intrinsics for SHA-384 and SHA-512 crypto hash functions not available on this CPU.");
   240     FLAG_SET_DEFAULT(UseSHA512Intrinsics, false);
   241   }
   243   if (!(UseSHA1Intrinsics || UseSHA256Intrinsics || UseSHA512Intrinsics)) {
   244     FLAG_SET_DEFAULT(UseSHA, false);
   245   }
   247   if (FLAG_IS_DEFAULT(UseMontgomeryMultiplyIntrinsic)) {
   248     UseMontgomeryMultiplyIntrinsic = true;
   249   }
   250   if (FLAG_IS_DEFAULT(UseMontgomerySquareIntrinsic)) {
   251     UseMontgomerySquareIntrinsic = true;
   252   }
   253 }
   255 void VM_Version::print_features() {
   256   tty->print_cr("Version: %s cache_line_size = %d", cpu_features(), (int) get_cache_line_size());
   257 }
   259 #ifdef COMPILER2
   260 // Determine section size on power6: If section size is 8 instructions,
   261 // there should be a difference between the two testloops of ~15 %. If
   262 // no difference is detected the section is assumed to be 32 instructions.
   263 void VM_Version::determine_section_size() {
   265   int unroll = 80;
   267   const int code_size = (2* unroll * 32 + 100)*BytesPerInstWord;
   269   // Allocate space for the code.
   270   ResourceMark rm;
   271   CodeBuffer cb("detect_section_size", code_size, 0);
   272   MacroAssembler* a = new MacroAssembler(&cb);
   274   uint32_t *code = (uint32_t *)a->pc();
   275   // Emit code.
   276   void (*test1)() = (void(*)())(void *)a->function_entry();
   278   Label l1;
   280   a->li(R4, 1);
   281   a->sldi(R4, R4, 28);
   282   a->b(l1);
   283   a->align(CodeEntryAlignment);
   285   a->bind(l1);
   287   for (int i = 0; i < unroll; i++) {
   288     // Schleife 1
   289     // ------- sector 0 ------------
   290     // ;; 0
   291     a->nop();                   // 1
   292     a->fpnop0();                // 2
   293     a->fpnop1();                // 3
   294     a->addi(R4,R4, -1); // 4
   296     // ;;  1
   297     a->nop();                   // 5
   298     a->fmr(F6, F6);             // 6
   299     a->fmr(F7, F7);             // 7
   300     a->endgroup();              // 8
   301     // ------- sector 8 ------------
   303     // ;;  2
   304     a->nop();                   // 9
   305     a->nop();                   // 10
   306     a->fmr(F8, F8);             // 11
   307     a->fmr(F9, F9);             // 12
   309     // ;;  3
   310     a->nop();                   // 13
   311     a->fmr(F10, F10);           // 14
   312     a->fmr(F11, F11);           // 15
   313     a->endgroup();              // 16
   314     // -------- sector 16 -------------
   316     // ;;  4
   317     a->nop();                   // 17
   318     a->nop();                   // 18
   319     a->fmr(F15, F15);           // 19
   320     a->fmr(F16, F16);           // 20
   322     // ;;  5
   323     a->nop();                   // 21
   324     a->fmr(F17, F17);           // 22
   325     a->fmr(F18, F18);           // 23
   326     a->endgroup();              // 24
   327     // ------- sector 24  ------------
   329     // ;;  6
   330     a->nop();                   // 25
   331     a->nop();                   // 26
   332     a->fmr(F19, F19);           // 27
   333     a->fmr(F20, F20);           // 28
   335     // ;;  7
   336     a->nop();                   // 29
   337     a->fmr(F21, F21);           // 30
   338     a->fmr(F22, F22);           // 31
   339     a->brnop0();                // 32
   341     // ------- sector 32 ------------
   342   }
   344   // ;; 8
   345   a->cmpdi(CCR0, R4, unroll);   // 33
   346   a->bge(CCR0, l1);             // 34
   347   a->blr();
   349   // Emit code.
   350   void (*test2)() = (void(*)())(void *)a->function_entry();
   351   // uint32_t *code = (uint32_t *)a->pc();
   353   Label l2;
   355   a->li(R4, 1);
   356   a->sldi(R4, R4, 28);
   357   a->b(l2);
   358   a->align(CodeEntryAlignment);
   360   a->bind(l2);
   362   for (int i = 0; i < unroll; i++) {
   363     // Schleife 2
   364     // ------- sector 0 ------------
   365     // ;; 0
   366     a->brnop0();                  // 1
   367     a->nop();                     // 2
   368     //a->cmpdi(CCR0, R4, unroll);
   369     a->fpnop0();                  // 3
   370     a->fpnop1();                  // 4
   371     a->addi(R4,R4, -1);           // 5
   373     // ;; 1
   375     a->nop();                     // 6
   376     a->fmr(F6, F6);               // 7
   377     a->fmr(F7, F7);               // 8
   378     // ------- sector 8 ---------------
   380     // ;; 2
   381     a->endgroup();                // 9
   383     // ;; 3
   384     a->nop();                     // 10
   385     a->nop();                     // 11
   386     a->fmr(F8, F8);               // 12
   388     // ;; 4
   389     a->fmr(F9, F9);               // 13
   390     a->nop();                     // 14
   391     a->fmr(F10, F10);             // 15
   393     // ;; 5
   394     a->fmr(F11, F11);             // 16
   395     // -------- sector 16 -------------
   397     // ;; 6
   398     a->endgroup();                // 17
   400     // ;; 7
   401     a->nop();                     // 18
   402     a->nop();                     // 19
   403     a->fmr(F15, F15);             // 20
   405     // ;; 8
   406     a->fmr(F16, F16);             // 21
   407     a->nop();                     // 22
   408     a->fmr(F17, F17);             // 23
   410     // ;; 9
   411     a->fmr(F18, F18);             // 24
   412     // -------- sector 24 -------------
   414     // ;; 10
   415     a->endgroup();                // 25
   417     // ;; 11
   418     a->nop();                     // 26
   419     a->nop();                     // 27
   420     a->fmr(F19, F19);             // 28
   422     // ;; 12
   423     a->fmr(F20, F20);             // 29
   424     a->nop();                     // 30
   425     a->fmr(F21, F21);             // 31
   427     // ;; 13
   428     a->fmr(F22, F22);             // 32
   429   }
   431   // -------- sector 32 -------------
   432   // ;; 14
   433   a->cmpdi(CCR0, R4, unroll); // 33
   434   a->bge(CCR0, l2);           // 34
   436   a->blr();
   437   uint32_t *code_end = (uint32_t *)a->pc();
   438   a->flush();
   440   double loop1_seconds,loop2_seconds, rel_diff;
   441   uint64_t start1, stop1;
   443   start1 = os::current_thread_cpu_time(false);
   444   (*test1)();
   445   stop1 = os::current_thread_cpu_time(false);
   446   loop1_seconds = (stop1- start1) / (1000 *1000 *1000.0);
   449   start1 = os::current_thread_cpu_time(false);
   450   (*test2)();
   451   stop1 = os::current_thread_cpu_time(false);
   453   loop2_seconds = (stop1 - start1) / (1000 *1000 *1000.0);
   455   rel_diff = (loop2_seconds - loop1_seconds) / loop1_seconds *100;
   457   if (PrintAssembly) {
   458     ttyLocker ttyl;
   459     tty->print_cr("Decoding section size detection stub at " INTPTR_FORMAT " before execution:", p2i(code));
   460     Disassembler::decode((u_char*)code, (u_char*)code_end, tty);
   461     tty->print_cr("Time loop1 :%f", loop1_seconds);
   462     tty->print_cr("Time loop2 :%f", loop2_seconds);
   463     tty->print_cr("(time2 - time1) / time1 = %f %%", rel_diff);
   465     if (rel_diff > 12.0) {
   466       tty->print_cr("Section Size 8 Instructions");
   467     } else{
   468       tty->print_cr("Section Size 32 Instructions or Power5");
   469     }
   470   }
   472 #if 0 // TODO: PPC port
   473   // Set sector size (if not set explicitly).
   474   if (FLAG_IS_DEFAULT(Power6SectorSize128PPC64)) {
   475     if (rel_diff > 12.0) {
   476       PdScheduling::power6SectorSize = 0x20;
   477     } else {
   478       PdScheduling::power6SectorSize = 0x80;
   479     }
   480   } else if (Power6SectorSize128PPC64) {
   481     PdScheduling::power6SectorSize = 0x80;
   482   } else {
   483     PdScheduling::power6SectorSize = 0x20;
   484   }
   485 #endif
   486   if (UsePower6SchedulerPPC64) Unimplemented();
   487 }
   488 #endif // COMPILER2
   490 void VM_Version::determine_features() {
   491 #if defined(ABI_ELFv2)
   492   const int code_size = (num_features+1+2*7)*BytesPerInstWord; // TODO(asmundak): calculation is incorrect.
   493 #else
   494   // 7 InstWords for each call (function descriptor + blr instruction).
   495   const int code_size = (num_features+1+2*7)*BytesPerInstWord;
   496 #endif
   497   int features = 0;
   499   // create test area
   500   enum { BUFFER_SIZE = 2*4*K }; // Needs to be >=2* max cache line size (cache line size can't exceed min page size).
   501   char test_area[BUFFER_SIZE];
   502   char *mid_of_test_area = &test_area[BUFFER_SIZE>>1];
   504   // Allocate space for the code.
   505   ResourceMark rm;
   506   CodeBuffer cb("detect_cpu_features", code_size, 0);
   507   MacroAssembler* a = new MacroAssembler(&cb);
   509   // Must be set to true so we can generate the test code.
   510   _features = VM_Version::all_features_m;
   512   // Emit code.
   513   void (*test)(address addr, uint64_t offset)=(void(*)(address addr, uint64_t offset))(void *)a->function_entry();
   514   uint32_t *code = (uint32_t *)a->pc();
   515   // Don't use R0 in ldarx.
   516   // Keep R3_ARG1 unmodified, it contains &field (see below).
   517   // Keep R4_ARG2 unmodified, it contains offset = 0 (see below).
   518   a->fsqrt(F3, F4);                            // code[0] -> fsqrt_m
   519   a->fsqrts(F3, F4);                           // code[1] -> fsqrts_m
   520   a->isel(R7, R5, R6, 0);                      // code[2] -> isel_m
   521   a->ldarx_unchecked(R7, R3_ARG1, R4_ARG2, 1); // code[3] -> lxarx_m
   522   a->cmpb(R7, R5, R6);                         // code[4] -> bcmp
   523   //a->mftgpr(R7, F3);                         // code[5] -> mftgpr
   524   a->popcntb(R7, R5);                          // code[6] -> popcntb
   525   a->popcntw(R7, R5);                          // code[7] -> popcntw
   526   a->fcfids(F3, F4);                           // code[8] -> fcfids
   527   a->vand(VR0, VR0, VR0);                      // code[9] -> vand
   528   a->lqarx_unchecked(R7, R3_ARG1, R4_ARG2, 1); // code[10] -> lqarx_m
   529   a->vcipher(VR0, VR1, VR2);                   // code[11] -> vcipher
   530   a->vpmsumb(VR0, VR1, VR2);                   // code[12] -> vpmsumb
   531   a->mfdscr(R0);                               // code[13] -> mfdscr
   532   a->lxvd2x(VSR0, R3_ARG1);                    // code[14] -> vsx
   533   a->vshasigmaw(VR0, VR1, 1, 0xF);             // code[15] -> vshasig
   534   a->blr();
   536   // Emit function to set one cache line to zero. Emit function descriptor and get pointer to it.
   537   void (*zero_cacheline_func_ptr)(char*) = (void(*)(char*))(void *)a->function_entry();
   538   a->dcbz(R3_ARG1); // R3_ARG1 = addr
   539   a->blr();
   541   uint32_t *code_end = (uint32_t *)a->pc();
   542   a->flush();
   543   _features = VM_Version::unknown_m;
   545   // Print the detection code.
   546   if (PrintAssembly) {
   547     ttyLocker ttyl;
   548     tty->print_cr("Decoding cpu-feature detection stub at " INTPTR_FORMAT " before execution:", p2i(code));
   549     Disassembler::decode((u_char*)code, (u_char*)code_end, tty);
   550   }
   552   // Measure cache line size.
   553   memset(test_area, 0xFF, BUFFER_SIZE); // Fill test area with 0xFF.
   554   (*zero_cacheline_func_ptr)(mid_of_test_area); // Call function which executes dcbz to the middle.
   555   int count = 0; // count zeroed bytes
   556   for (int i = 0; i < BUFFER_SIZE; i++) if (test_area[i] == 0) count++;
   557   guarantee(is_power_of_2(count), "cache line size needs to be a power of 2");
   558   _measured_cache_line_size = count;
   560   // Execute code. Illegal instructions will be replaced by 0 in the signal handler.
   561   VM_Version::_is_determine_features_test_running = true;
   562   (*test)((address)mid_of_test_area, (uint64_t)0);
   563   VM_Version::_is_determine_features_test_running = false;
   565   // determine which instructions are legal.
   566   int feature_cntr = 0;
   567   if (code[feature_cntr++]) features |= fsqrt_m;
   568   if (code[feature_cntr++]) features |= fsqrts_m;
   569   if (code[feature_cntr++]) features |= isel_m;
   570   if (code[feature_cntr++]) features |= lxarxeh_m;
   571   if (code[feature_cntr++]) features |= cmpb_m;
   572   //if(code[feature_cntr++])features |= mftgpr_m;
   573   if (code[feature_cntr++]) features |= popcntb_m;
   574   if (code[feature_cntr++]) features |= popcntw_m;
   575   if (code[feature_cntr++]) features |= fcfids_m;
   576   if (code[feature_cntr++]) features |= vand_m;
   577   if (code[feature_cntr++]) features |= lqarx_m;
   578   if (code[feature_cntr++]) features |= vcipher_m;
   579   if (code[feature_cntr++]) features |= vpmsumb_m;
   580   if (code[feature_cntr++]) features |= mfdscr_m;
   581   if (code[feature_cntr++]) features |= vsx_m;
   582   if (code[feature_cntr++]) features |= vshasig_m;
   584   // Print the detection code.
   585   if (PrintAssembly) {
   586     ttyLocker ttyl;
   587     tty->print_cr("Decoding cpu-feature detection stub at " INTPTR_FORMAT " after execution:", p2i(code));
   588     Disassembler::decode((u_char*)code, (u_char*)code_end, tty);
   589   }
   591   _features = features;
   592 }
   594 // Power 8: Configure Data Stream Control Register.
   595 void VM_Version::config_dscr() {
   596   assert(has_lqarx(), "Only execute on Power 8 or later!");
   598   // 7 InstWords for each call (function descriptor + blr instruction).
   599   const int code_size = (2+2*7)*BytesPerInstWord;
   601   // Allocate space for the code.
   602   ResourceMark rm;
   603   CodeBuffer cb("config_dscr", code_size, 0);
   604   MacroAssembler* a = new MacroAssembler(&cb);
   606   // Emit code.
   607   uint64_t (*get_dscr)() = (uint64_t(*)())(void *)a->function_entry();
   608   uint32_t *code = (uint32_t *)a->pc();
   609   a->mfdscr(R3);
   610   a->blr();
   612   void (*set_dscr)(long) = (void(*)(long))(void *)a->function_entry();
   613   a->mtdscr(R3);
   614   a->blr();
   616   uint32_t *code_end = (uint32_t *)a->pc();
   617   a->flush();
   619   // Print the detection code.
   620   if (PrintAssembly) {
   621     ttyLocker ttyl;
   622     tty->print_cr("Decoding dscr configuration stub at " INTPTR_FORMAT " before execution:", p2i(code));
   623     Disassembler::decode((u_char*)code, (u_char*)code_end, tty);
   624   }
   626   // Apply the configuration if needed.
   627   _dscr_val = (*get_dscr)();
   628   if (Verbose) {
   629     tty->print_cr("dscr value was 0x%lx" , _dscr_val);
   630   }
   631   bool change_requested = false;
   632   if (DSCR_PPC64 != (uintx)-1) {
   633     _dscr_val = DSCR_PPC64;
   634     change_requested = true;
   635   }
   636   if (DSCR_DPFD_PPC64 <= 7) {
   637     uint64_t mask = 0x7;
   638     if ((_dscr_val & mask) != DSCR_DPFD_PPC64) {
   639       _dscr_val = (_dscr_val & ~mask) | (DSCR_DPFD_PPC64);
   640       change_requested = true;
   641     }
   642   }
   643   if (DSCR_URG_PPC64 <= 7) {
   644     uint64_t mask = 0x7 << 6;
   645     if ((_dscr_val & mask) != DSCR_DPFD_PPC64 << 6) {
   646       _dscr_val = (_dscr_val & ~mask) | (DSCR_URG_PPC64 << 6);
   647       change_requested = true;
   648     }
   649   }
   650   if (change_requested) {
   651     (*set_dscr)(_dscr_val);
   652     if (Verbose) {
   653       tty->print_cr("dscr was set to 0x%lx" , (*get_dscr)());
   654     }
   655   }
   656 }
   658 static int saved_features = 0;
   660 void VM_Version::allow_all() {
   661   saved_features = _features;
   662   _features      = all_features_m;
   663 }
   665 void VM_Version::revert() {
   666   _features = saved_features;
   667 }

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