osfmk/i386/machine_routines_asm.s

   1 /*
   2  * Copyright (c) 2000-2007 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/rtclock.h>
  31 #include <i386/proc_reg.h>
  32 #include <i386/eflags.h>
  33
  34 #include <i386/postcode.h>
  35 #include <i386/apic.h>
  36 #include <assym.s>
  37
  38 /*
  39 **      ml_get_timebase()
  40 **
  41 **      Entry   - %esp contains pointer to 64 bit structure.
  42 **
  43 **      Exit    - 64 bit structure filled in.
  44 **
  45 */
  46 ENTRY(ml_get_timebase)
  47
  48                         movl    S_ARG0, %ecx
  49
  50                         lfence
  51                         rdtsc
  52                         lfence
  53
  54                         movl    %edx, 0(%ecx)
  55                         movl    %eax, 4(%ecx)
  56
  57                         ret
  58
  59 /*
  60  *      Convert between various timer units
  61  *
  62  *              uint64_t tmrCvt(uint64_t time, uint64_t *conversion)
  63  *
  64  *              This code converts 64-bit time units to other units.
  65  *              For example, the TSC is converted to HPET units.
  66  *
  67  *              Time is a 64-bit integer that is some number of ticks.
  68  *              Conversion is 64-bit fixed point number which is composed
  69  *              of a 32 bit integer and a 32 bit fraction.
  70  *
  71  *              The time ticks are multiplied by the conversion factor.  The
  72  *              calculations are done as a 128-bit value but both the high
  73  *              and low words are dropped.  The high word is overflow and the
  74  *              low word is the fraction part of the result.
  75  *
  76  *              We return a 64-bit value.
  77  *
  78  *              Note that we can use this function to multiply 2 conversion factors.
  79  *              We do this in order to calculate the multiplier used to convert
  80  *              directly between any two units.
  81  *
  82  */
  83
  84                         .globl  EXT(tmrCvt)
  85                         .align FALIGN
  86
  87 LEXT(tmrCvt)
  88
  89                         pushl   %ebp                                    // Save a volatile
  90                         movl    %esp,%ebp                               // Get the parameters - 8
  91                         pushl   %ebx                                    // Save a volatile
  92                         pushl   %esi                                    // Save a volatile
  93                         pushl   %edi                                    // Save a volatile
  94
  95 //                      %ebp + 8        - low-order ts
  96 //                      %ebp + 12       - high-order ts
  97 //                      %ebp + 16       - low-order cvt
  98 //                      %ebp + 20       - high-order cvt
  99
 100                         movl    8(%ebp),%eax                    // Get low-order ts
 101                         mull    16(%ebp)                                // Multiply by low-order conversion
 102                         movl    %edx,%edi                               // Need to save only the high order part
 103
 104                         movl    12(%ebp),%eax                   // Get the high-order ts
 105                         mull    16(%ebp)                                // Multiply by low-order conversion
 106                         addl    %eax,%edi                               // Add in the overflow from the low x low calculation
 107                         adcl    $0,%edx                                 // Add in any overflow to high high part
 108                         movl    %edx,%esi                               // Save high high part
 109
 110 //                      We now have the upper 64 bits of the 96 bit multiply of ts and the low half of cvt
 111 //                      in %esi:%edi
 112
 113                         movl    8(%ebp),%eax                    // Get low-order ts
 114                         mull    20(%ebp)                                // Multiply by high-order conversion
 115                         movl    %eax,%ebx                               // Need to save the low order part
 116                         movl    %edx,%ecx                               // Need to save the high order part
 117
 118                         movl    12(%ebp),%eax                   // Get the high-order ts
 119                         mull    20(%ebp)                                // Multiply by high-order conversion
 120
 121 //                      Now have %ecx:%ebx as low part of high low and %edx:%eax as high part of high high
 122 //                      We don't care about the highest word since it is overflow
 123
 124                         addl    %edi,%ebx                               // Add the low words
 125                         adcl    %ecx,%esi                               // Add in the high plus carry from low
 126                         addl    %eax,%esi                               // Add in the rest of the high
 127
 128                         movl    %ebx,%eax                               // Pass back low word
 129                         movl    %esi,%edx                               // and the high word
 130
 131                         popl    %edi                                    // Restore a volatile
 132                         popl    %esi                                    // Restore a volatile
 133                         popl    %ebx                                    // Restore a volatile
 134                         popl    %ebp                                    // Restore a volatile
 135
 136                         ret                                             // Leave...
 137
 138
 139 /* void             _rtc_nanotime_store(uint64_t                tsc,
 140                                         uint64_t                nsec,
 141                                         uint32_t                scale,
 142                                         uint32_t                shift,
 143                                         rtc_nanotime_t  *dst) ;
 144 */
 145                         .globl  EXT(_rtc_nanotime_store)
 146                         .align  FALIGN
 147
 148 LEXT(_rtc_nanotime_store)
 149                 push            %ebp
 150                 movl            %esp,%ebp
 151                 push            %esi
 152
 153                 mov             32(%ebp),%edx                           /* get ptr to rtc_nanotime_info */
 154
 155                 movl            RNT_GENERATION(%edx),%esi               /* get current generation */
 156                 movl            $0,RNT_GENERATION(%edx)                 /* flag data as being updated */
 157
 158                 mov             8(%ebp),%eax
 159                 mov             %eax,RNT_TSC_BASE(%edx)
 160                 mov             12(%ebp),%eax
 161                 mov             %eax,RNT_TSC_BASE+4(%edx)
 162
 163                 mov             24(%ebp),%eax
 164                 mov             %eax,RNT_SCALE(%edx)
 165
 166                 mov             28(%ebp),%eax
 167                 mov             %eax,RNT_SHIFT(%edx)
 168
 169                 mov             16(%ebp),%eax
 170                 mov             %eax,RNT_NS_BASE(%edx)
 171                 mov             20(%ebp),%eax
 172                 mov             %eax,RNT_NS_BASE+4(%edx)
 173
 174                 incl            %esi                                    /* next generation */
 175                 jnz             1f
 176                 incl            %esi                                    /* skip 0, which is a flag */
 177 1:              movl            %esi,RNT_GENERATION(%edx)               /* update generation and make usable */
 178
 179                 pop             %esi
 180                 pop             %ebp
 181                 ret
 182
 183
 184 /* unint64_t _rtc_nanotime_read( rtc_nanotime_t *rntp, int slow );
 185  *
 186  * This is the same as the commpage nanotime routine, except that it uses the
 187  * kernel internal "rtc_nanotime_info" data instead of the commpage data.  The two copies
 188  * of data (one in the kernel and one in user space) are kept in sync by rtc_clock_napped().
 189  *
 190  * Warning!  There is another copy of this code in osfmk/i386/locore.s.  The
 191  * two versions must be kept in sync with each other!
 192  *
 193  * There are actually two versions of the algorithm, one each for "slow" and "fast"
 194  * processors.  The more common "fast" algorithm is:
 195  *
 196  *      nanoseconds = (((rdtsc - rnt_tsc_base) * rnt_tsc_scale) / 2**32) - rnt_ns_base;
 197  *
 198  * Of course, the divide by 2**32 is a nop.  rnt_tsc_scale is a constant computed during initialization:
 199  *
 200  *      rnt_tsc_scale = (10e9 * 2**32) / tscFreq;
 201  *
 202  * The "slow" algorithm uses long division:
 203  *
 204  *      nanoseconds = (((rdtsc - rnt_tsc_base) * 10e9) / tscFreq) - rnt_ns_base;
 205  *
 206  * Since this routine is not synchronized and can be called in any context,
 207  * we use a generation count to guard against seeing partially updated data.  In addition,
 208  * the _rtc_nanotime_store() routine -- just above -- zeroes the generation before
 209  * updating the data, and stores the nonzero generation only after all other data has been
 210  * stored.  Because IA32 guarantees that stores by one processor must be seen in order
 211  * by another, we can avoid using a lock.  We spin while the generation is zero.
 212  *
 213  * In accordance with the ABI, we return the 64-bit nanotime in %edx:%eax.
 214  */
 215
 216                 .globl  EXT(_rtc_nanotime_read)
 217                 .align  FALIGN
 218 LEXT(_rtc_nanotime_read)
 219                 pushl           %ebp
 220                 movl            %esp,%ebp
 221                 pushl           %esi
 222                 pushl           %edi
 223                 pushl           %ebx
 224                 movl            8(%ebp),%edi                            /* get ptr to rtc_nanotime_info */
 225                 movl            12(%ebp),%eax                           /* get "slow" flag */
 226                 testl           %eax,%eax
 227                 jnz             Lslow
 228
 229                 /* Processor whose TSC frequency is faster than SLOW_TSC_THRESHOLD */
 230                 RTC_NANOTIME_READ_FAST()
 231
 232                 popl            %ebx
 233                 popl            %edi
 234                 popl            %esi
 235                 popl            %ebp
 236                 ret
 237
 238                 /* Processor whose TSC frequency is slower than or equal to SLOW_TSC_THRESHOLD */
 239 Lslow:
 240                 movl            RNT_GENERATION(%edi),%esi               /* get generation (0 if being changed) */
 241                 testl           %esi,%esi                               /* if being changed, loop until stable */
 242                 jz              Lslow
 243                 pushl           %esi                                    /* save generation */
 244                 pushl           RNT_SHIFT(%edi)                         /* save low 32 bits of tscFreq */
 245
 246                 lfence
 247                 rdtsc                                                   /* get TSC in %edx:%eax */
 248                 lfence
 249                 subl            RNT_TSC_BASE(%edi),%eax
 250                 sbbl            RNT_TSC_BASE+4(%edi),%edx
 251
 252                 /*
 253                 * Do the math to convert tsc ticks to nanoseconds.  We first
 254                 * do long multiply of 1 billion times the tsc.  Then we do
 255                 * long division by the tsc frequency
 256                 */
 257                 mov             $1000000000, %ecx                       /* number of nanoseconds in a second */
 258                 mov             %edx, %ebx
 259                 mul             %ecx
 260                 mov             %edx, %edi
 261                 mov             %eax, %esi
 262                 mov             %ebx, %eax
 263                 mul             %ecx
 264                 add             %edi, %eax
 265                 adc             $0, %edx                                /* result in edx:eax:esi */
 266                 mov             %eax, %edi
 267                 popl            %ecx                                    /* get low 32 tscFreq */
 268                 xor             %eax, %eax
 269                 xchg            %edx, %eax
 270                 div             %ecx
 271                 xor             %eax, %eax
 272                 mov             %edi, %eax
 273                 div             %ecx
 274                 mov             %eax, %ebx
 275                 mov             %esi, %eax
 276                 div             %ecx
 277                 mov             %ebx, %edx                              /* result in edx:eax */
 278
 279                 movl            8(%ebp),%edi                            /* recover ptr to rtc_nanotime_info */
 280                 popl            %esi                                    /* recover generation */
 281
 282                 addl            RNT_NS_BASE(%edi),%eax
 283                 adcl            RNT_NS_BASE+4(%edi),%edx
 284
 285                 cmpl            RNT_GENERATION(%edi),%esi               /* have the parameters changed? */
 286                 jne             Lslow                                   /* yes, loop until stable */
 287
 288                 pop             %ebx
 289                 pop             %edi
 290                 pop             %esi
 291                 pop             %ebp
 292                 ret                                                     /* result in edx:eax */
 293