The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/osfmk/i386/machine_routines_asm.s

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    1 /*
    2  * Copyright (c) 2000-2010 Apple Inc. All rights reserved.
    3  *
    4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
    5  * 
    6  * This file contains Original Code and/or Modifications of Original Code
    7  * as defined in and that are subject to the Apple Public Source License
    8  * Version 2.0 (the 'License'). You may not use this file except in
    9  * compliance with the License. The rights granted to you under the License
   10  * may not be used to create, or enable the creation or redistribution of,
   11  * unlawful or unlicensed copies of an Apple operating system, or to
   12  * circumvent, violate, or enable the circumvention or violation of, any
   13  * terms of an Apple operating system software license agreement.
   14  * 
   15  * Please obtain a copy of the License at
   16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
   17  * 
   18  * The Original Code and all software distributed under the License are
   19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
   20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
   21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
   22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
   23  * Please see the License for the specific language governing rights and
   24  * limitations under the License.
   25  * 
   26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
   27  */
   28  
   29 #include <i386/asm.h>
   30 #include <i386/apic.h>
   31 #include <i386/eflags.h>
   32 #include <i386/rtclock_asm.h>
   33 #include <i386/postcode.h>
   34 #include <i386/proc_reg.h>
   35 #include <assym.s>
   36 
   37 /*
   38 **      ml_get_timebase()
   39 **
   40 **      Entry   - %esp contains pointer to 64 bit structure.
   41 **
   42 **      Exit    - 64 bit structure filled in.
   43 **
   44 */
   45 ENTRY(ml_get_timebase)
   46 
   47                         movl    S_ARG0, %ecx
   48                         
   49                         lfence
   50                         rdtsc
   51                         lfence
   52                         
   53                         movl    %edx, 0(%ecx)
   54                         movl    %eax, 4(%ecx)
   55                         
   56                         ret
   57 
   58 /*
   59  *      Convert between various timer units 
   60  *
   61  *              uint64_t tmrCvt(uint64_t time, uint64_t *conversion)
   62  *
   63  *              This code converts 64-bit time units to other units.
   64  *              For example, the TSC is converted to HPET units.
   65  *
   66  *              Time is a 64-bit integer that is some number of ticks.
   67  *              Conversion is 64-bit fixed point number which is composed
   68  *              of a 32 bit integer and a 32 bit fraction. 
   69  *
   70  *              The time ticks are multiplied by the conversion factor.  The
   71  *              calculations are done as a 128-bit value but both the high
   72  *              and low words are dropped.  The high word is overflow and the
   73  *              low word is the fraction part of the result.
   74  *
   75  *              We return a 64-bit value.
   76  *
   77  *              Note that we can use this function to multiply 2 conversion factors.
   78  *              We do this in order to calculate the multiplier used to convert
   79  *              directly between any two units.
   80  *
   81  */
   82 
   83                         .globl  EXT(tmrCvt)
   84                         .align FALIGN
   85 
   86 LEXT(tmrCvt)
   87 
   88                         pushl   %ebp                                    // Save a volatile
   89                         movl    %esp,%ebp                               // Get the parameters - 8
   90                         pushl   %ebx                                    // Save a volatile
   91                         pushl   %esi                                    // Save a volatile
   92                         pushl   %edi                                    // Save a volatile
   93 
   94 //                      %ebp + 8        - low-order ts
   95 //                      %ebp + 12       - high-order ts
   96 //                      %ebp + 16       - low-order cvt
   97 //                      %ebp + 20       - high-order cvt
   98 
   99                         movl    8(%ebp),%eax                    // Get low-order ts
  100                         mull    16(%ebp)                                // Multiply by low-order conversion
  101                         movl    %edx,%edi                               // Need to save only the high order part
  102                         
  103                         movl    12(%ebp),%eax                   // Get the high-order ts
  104                         mull    16(%ebp)                                // Multiply by low-order conversion
  105                         addl    %eax,%edi                               // Add in the overflow from the low x low calculation
  106                         adcl    $0,%edx                                 // Add in any overflow to high high part
  107                         movl    %edx,%esi                               // Save high high part
  108                         
  109 //                      We now have the upper 64 bits of the 96 bit multiply of ts and the low half of cvt
  110 //                      in %esi:%edi
  111 
  112                         movl    8(%ebp),%eax                    // Get low-order ts
  113                         mull    20(%ebp)                                // Multiply by high-order conversion
  114                         movl    %eax,%ebx                               // Need to save the low order part
  115                         movl    %edx,%ecx                               // Need to save the high order part
  116                         
  117                         movl    12(%ebp),%eax                   // Get the high-order ts
  118                         mull    20(%ebp)                                // Multiply by high-order conversion
  119                         
  120 //                      Now have %ecx:%ebx as low part of high low and %edx:%eax as high part of high high
  121 //                      We don't care about the highest word since it is overflow
  122                         
  123                         addl    %edi,%ebx                               // Add the low words
  124                         adcl    %ecx,%esi                               // Add in the high plus carry from low
  125                         addl    %eax,%esi                               // Add in the rest of the high
  126                         
  127                         movl    %ebx,%eax                               // Pass back low word
  128                         movl    %esi,%edx                               // and the high word
  129                         
  130                         popl    %edi                                    // Restore a volatile
  131                         popl    %esi                                    // Restore a volatile
  132                         popl    %ebx                                    // Restore a volatile
  133                         popl    %ebp                                    // Restore a volatile
  134 
  135                         ret                                             // Leave...
  136 
  137 
  138 /* void  _rtc_nanotime_adjust(  
  139                 uint64_t         tsc_base_delta,
  140                 rtc_nanotime_t  *dst);
  141 */
  142         .globl  EXT(_rtc_nanotime_adjust)
  143         .align  FALIGN
  144 
  145 LEXT(_rtc_nanotime_adjust)
  146         mov     12(%esp),%edx                   /* ptr to rtc_nanotime_info */
  147         
  148         movl    RNT_GENERATION(%edx),%ecx       /* get current generation */
  149         movl    $0,RNT_GENERATION(%edx)         /* flag data as being updated */
  150 
  151         movl    4(%esp),%eax                    /* get lower 32-bits of delta */
  152         addl    %eax,RNT_TSC_BASE(%edx)
  153         adcl    $0,RNT_TSC_BASE+4(%edx)         /* propagate carry */
  154 
  155         incl    %ecx                            /* next generation */
  156         jnz     1f
  157         incl    %ecx                            /* skip 0, which is a flag */
  158 1:      movl    %ecx,RNT_GENERATION(%edx)       /* update generation and make usable */
  159 
  160         ret
  161 
  162 
  163 /* unint64_t _rtc_nanotime_read( rtc_nanotime_t *rntp, int slow );
  164  *
  165  * This is the same as the commpage nanotime routine, except that it uses the
  166  * kernel internal "rtc_nanotime_info" data instead of the commpage data.  The two copies
  167  * of data (one in the kernel and one in user space) are kept in sync by rtc_clock_napped().
  168  *
  169  * Warning!  There is another copy of this code in osfmk/i386/locore.s.  The
  170  * two versions must be kept in sync with each other!
  171  *
  172  * There are actually two versions of the algorithm, one each for "slow" and "fast"
  173  * processors.  The more common "fast" algorithm is:
  174  *
  175  *      nanoseconds = (((rdtsc - rnt_tsc_base) * rnt_tsc_scale) / 2**32) - rnt_ns_base;
  176  *
  177  * Of course, the divide by 2**32 is a nop.  rnt_tsc_scale is a constant computed during initialization:
  178  *
  179  *      rnt_tsc_scale = (10e9 * 2**32) / tscFreq;
  180  *
  181  * The "slow" algorithm uses long division:
  182  *
  183  *      nanoseconds = (((rdtsc - rnt_tsc_base) * 10e9) / tscFreq) - rnt_ns_base;
  184  *
  185  * Since this routine is not synchronized and can be called in any context, 
  186  * we use a generation count to guard against seeing partially updated data.  In addition,
  187  * the _rtc_nanotime_store() routine -- just above -- zeroes the generation before
  188  * updating the data, and stores the nonzero generation only after all other data has been
  189  * stored.  Because IA32 guarantees that stores by one processor must be seen in order
  190  * by another, we can avoid using a lock.  We spin while the generation is zero.
  191  *
  192  * In accordance with the ABI, we return the 64-bit nanotime in %edx:%eax.
  193  */
  194  
  195                 .globl  EXT(_rtc_nanotime_read)
  196                 .align  FALIGN
  197 LEXT(_rtc_nanotime_read)
  198                 pushl           %ebp
  199                 movl            %esp,%ebp
  200                 pushl           %esi
  201                 pushl           %edi
  202                 pushl           %ebx
  203                 movl            8(%ebp),%edi                            /* get ptr to rtc_nanotime_info */
  204                 movl            12(%ebp),%eax                           /* get "slow" flag */
  205                 testl           %eax,%eax
  206                 jnz             Lslow
  207                 
  208                 /* Processor whose TSC frequency is faster than SLOW_TSC_THRESHOLD */
  209                 PAL_RTC_NANOTIME_READ_FAST()
  210 
  211                 popl            %ebx
  212                 popl            %edi
  213                 popl            %esi
  214                 popl            %ebp
  215                 ret
  216 
  217                 /* Processor whose TSC frequency is slower than or equal to SLOW_TSC_THRESHOLD */
  218 Lslow:
  219                 movl            RNT_GENERATION(%edi),%esi               /* get generation (0 if being changed) */
  220                 testl           %esi,%esi                               /* if being changed, loop until stable */
  221                 jz              Lslow
  222                 pushl           %esi                                    /* save generation */
  223                 pushl           RNT_SHIFT(%edi)                         /* save low 32 bits of tscFreq */
  224 
  225                 lfence
  226                 rdtsc                                                   /* get TSC in %edx:%eax */
  227                 lfence
  228                 subl            RNT_TSC_BASE(%edi),%eax
  229                 sbbl            RNT_TSC_BASE+4(%edi),%edx
  230 
  231                 /*
  232                 * Do the math to convert tsc ticks to nanoseconds.  We first
  233                 * do long multiply of 1 billion times the tsc.  Then we do
  234                 * long division by the tsc frequency
  235                 */
  236                 mov             $1000000000, %ecx                       /* number of nanoseconds in a second */
  237                 mov             %edx, %ebx
  238                 mul             %ecx
  239                 mov             %edx, %edi
  240                 mov             %eax, %esi
  241                 mov             %ebx, %eax
  242                 mul             %ecx
  243                 add             %edi, %eax
  244                 adc             $0, %edx                                /* result in edx:eax:esi */
  245                 mov             %eax, %edi
  246                 popl            %ecx                                    /* get low 32 tscFreq */
  247                 xor             %eax, %eax
  248                 xchg            %edx, %eax
  249                 div             %ecx
  250                 xor             %eax, %eax
  251                 mov             %edi, %eax
  252                 div             %ecx
  253                 mov             %eax, %ebx
  254                 mov             %esi, %eax
  255                 div             %ecx
  256                 mov             %ebx, %edx                              /* result in edx:eax */
  257                 
  258                 movl            8(%ebp),%edi                            /* recover ptr to rtc_nanotime_info */
  259                 popl            %esi                                    /* recover generation */
  260 
  261                 addl            RNT_NS_BASE(%edi),%eax
  262                 adcl            RNT_NS_BASE+4(%edi),%edx
  263 
  264                 cmpl            RNT_GENERATION(%edi),%esi               /* have the parameters changed? */
  265                 jne             Lslow                                   /* yes, loop until stable */
  266 
  267                 pop             %ebx
  268                 pop             %edi
  269                 pop             %esi
  270                 pop             %ebp
  271                 ret                                                     /* result in edx:eax */
  272 
  273 
  274 
  275 /*
  276  * Timing routines.
  277  */
  278 Entry(timer_update)
  279         movl    4(%esp),%ecx
  280         movl    8(%esp),%eax
  281         movl    12(%esp),%edx
  282         movl    %eax,TIMER_HIGHCHK(%ecx)
  283         movl    %edx,TIMER_LOW(%ecx)
  284         movl    %eax,TIMER_HIGH(%ecx)
  285         ret
  286 
  287 Entry(timer_grab)
  288         movl    4(%esp),%ecx
  289 0:      movl    TIMER_HIGH(%ecx),%edx
  290         movl    TIMER_LOW(%ecx),%eax
  291         cmpl    TIMER_HIGHCHK(%ecx),%edx
  292         jne     0b
  293         ret
  294 
  295 
  296 Entry(call_continuation)
  297         movl    S_ARG0,%eax                     /* get continuation */
  298         movl    S_ARG1,%edx                     /* continuation param */
  299         movl    S_ARG2,%ecx                     /* wait result */
  300         movl    %gs:CPU_KERNEL_STACK,%esp       /* pop the stack */
  301         xorl    %ebp,%ebp                       /* zero frame pointer */
  302         subl    $8,%esp                         /* align the stack */
  303         pushl   %ecx
  304         pushl   %edx
  305         call    *%eax                           /* call continuation */
  306         addl    $16,%esp
  307         movl    %gs:CPU_ACTIVE_THREAD,%eax
  308         pushl   %eax
  309         call    EXT(thread_terminate)
  310 
  311 

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