machine_routines_asm.s [plain text]
/*
* Copyright (c) 2000-2008 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
#include <i386/asm.h>
#include <i386/rtclock.h>
#include <i386/proc_reg.h>
#include <i386/eflags.h>
#include <i386/postcode.h>
#include <i386/apic.h>
#include <assym.s>
/*
** ml_get_timebase()
**
** Entry - %rdi contains pointer to 64 bit structure.
**
** Exit - 64 bit structure filled in.
**
*/
ENTRY(ml_get_timebase)
lfence
rdtsc
lfence
shlq $32,%rdx
orq %rdx,%rax
movq %rax, (%rdi)
ret
/*
* Convert between various timer units
*
* This code converts 64-bit time units to other units.
* For example, the TSC is converted to HPET units.
*
* Time is a 64-bit integer that is some number of ticks.
* Conversion is 64-bit fixed point number which is composed
* of a 32 bit integer and a 32 bit fraction.
*
* The time ticks are multiplied by the conversion factor. The
* calculations are done as a 128-bit value but both the high
* and low words are dropped. The high word is overflow and the
* low word is the fraction part of the result.
*
* We return a 64-bit value.
*
* Note that we can use this function to multiply 2 conversion factors.
* We do this in order to calculate the multiplier used to convert
* directly between any two units.
*
* uint64_t tmrCvt(uint64_t time, // %rdi
* uint64_t conversion) // %rsi
*
*/
ENTRY(tmrCvt)
movq %rdi,%rax
mulq %rsi /* result is %rdx:%rax */
shrdq $32,%rdx,%rax /* %rdx:%rax >>= 32 */
ret
/*
* void _rtc_nanotime_store(
* uint64_t tsc, // %rdi
* uint64_t nsec, // %rsi
* uint32_t scale, // %rdx
* uint32_t shift, // %rcx
* rtc_nanotime_t *dst)ENTRY(_rtc_nanotime_store)
movl RNT_GENERATION(%r8),%eax /* get current generation */
movl $0,RNT_GENERATION(%r8) /* flag data as being updated */
movq %rdi,RNT_TSC_BASE(%r8)
movq %rsi,RNT_NS_BASE(%r8)
movl %edx,RNT_SCALE(%r8)
movl %ecx,RNT_SHIFT(%r8)
incl %eax /* next generation */
jnz 1f
incl %eax /* skip 0, which is a flag */
1: movl %eax,RNT_GENERATION(%r8) /* update generation */
ret
/*
* unint64_t _rtc_nanotime_read(rtc_nanotime_t *rntp, int slow) * This is the same as the commpage nanotime routine, except that it uses the
* kernel internal "rtc_nanotime_info" data instead of the commpage data.
* These two copies of data are kept in sync by rtc_clock_napped().
*
* Warning! There is another copy of this code in osfmk/x86_64/idt64.s.
* These are kept in sync by both using the RTC_NANOTIME_READ() macro.
*
* There are two versions of this algorithm, for "slow" and "fast" processors.
* The more common "fast" algorithm is:
*
* ns = (((rdtsc - rnt_tsc_base)*rnt_tsc_scale) / 2**32) + rnt_ns_base * Of course, the divide by 2**32 is a nop. rnt_tsc_scale is a constant
* computed during initialization:
*
* rnt_tsc_scale = (10e9 * 2**32) / tscFreq * The "slow" algorithm uses long division:
*
* ns = (((rdtsc - rnt_tsc_base) * 10e9) / tscFreq) + rnt_ns_base * Since this routine is not synchronized and can be called in any context,
* we use a generation count to guard against seeing partially updated data.
* In addition, the _rtc_nanotime_store() routine zeroes the generation before
* updating the data, and stores the nonzero generation only after all fields
* have been stored. Because IA32 guarantees that stores by one processor
* must be seen in order by another, we can avoid using a lock. We spin while
* the generation is zero.
*
* unint64_t _rtc_nanotime_read(
* rtc_nanotime_t *rntp, // %rdi
* int slow) */
ENTRY(_rtc_nanotime_read)
test %rsi,%rsi
jnz Lslow
/*
* Processor whose TSC frequency is faster than SLOW_TSC_THRESHOLD
*/
RTC_NANOTIME_READ_FAST()
ret
/*
* Processor whose TSC frequency is not faster than SLOW_TSC_THRESHOLD
* But K64 doesn't support this...
*/
Lslow:
lea 1f(%rip),%rdi
xorb %al,%al
call EXT(panic)
hlt
.data
1: String "_rtc_nanotime_read() - slow algorithm not supported"