/*
- * Copyright (c) 2003-2006 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2003-2007 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
COMMPAGE_DESCRIPTOR(mach_absolute_time,_COMM_PAGE_ABSOLUTE_TIME,0,0)
-/* Nanotime is being moved out of the way of bcopy in the commpage.
- * First we put it in both places, old and new. Then, when all the build
- * trains have rebuilt libSystem, we can remove the deprecated instance.
- */
/* return nanotime in %edx:%eax */
-Lold_nanotime:
+
Lnanotime:
- push %ebp
- mov %esp,%ebp
- push %esi
- push %edi
- push %ebx
+ pushl %ebp
+ movl %esp,%ebp
+ pushl %esi
+ pushl %ebx
0:
- mov _COMM_PAGE_NT_TSC_BASE,%esi
- mov _COMM_PAGE_NT_TSC_BASE+4,%edi
+ movl _COMM_PAGE_NT_GENERATION,%esi /* get generation (0 if being changed) */
+ testl %esi,%esi /* if being updated, loop until stable */
+ jz 0b
+
+ lfence
+ rdtsc /* get TSC in %edx:%eax */
+ lfence
- rdtsc
- sub %esi,%eax
- sbb %edi,%edx
+ subl _COMM_PAGE_NT_TSC_BASE,%eax
+ sbbl _COMM_PAGE_NT_TSC_BASE+4,%edx
- mov _COMM_PAGE_NT_SCALE,%ecx
+ movl _COMM_PAGE_NT_SCALE,%ecx
- mov %edx,%ebx
+ movl %edx,%ebx
mull %ecx
- mov %ebx,%eax
- mov %edx,%ebx
+ movl %ebx,%eax
+ movl %edx,%ebx
mull %ecx
- add %ebx,%eax
- adc $0,%edx
+ addl %ebx,%eax
+ adcl $0,%edx
+
+ addl _COMM_PAGE_NT_NS_BASE,%eax
+ adcl _COMM_PAGE_NT_NS_BASE+4,%edx
+
+ cmpl _COMM_PAGE_NT_GENERATION,%esi /* have the parameters changed? */
+ jne 0b /* yes, loop until stable */
+
+ popl %ebx
+ popl %esi
+ popl %ebp
+ ret
+
+ COMMPAGE_DESCRIPTOR(nanotime,_COMM_PAGE_NANOTIME,0,kSlow)
+
+
+/* nanotime routine for machines slower than ~1Gz (SLOW_TSC_THRESHOLD) */
+Lnanotime_slow:
+ push %ebp
+ mov %esp,%ebp
+ push %esi
+ push %edi
+ push %ebx
+
+0:
+ movl _COMM_PAGE_NT_GENERATION,%esi
+ testl %esi,%esi /* if generation is 0, data being changed */
+ jz 0b /* so loop until stable */
+
+ lfence
+ rdtsc /* get TSC in %edx:%eax */
+ lfence
+ subl _COMM_PAGE_NT_TSC_BASE,%eax
+ sbbl _COMM_PAGE_NT_TSC_BASE+4,%edx
+
+ pushl %esi /* save generation */
+ /*
+ * Do the math to convert tsc ticks to nanoseconds. We first
+ * do long multiply of 1 billion times the tsc. Then we do
+ * long division by the tsc frequency
+ */
+ mov $1000000000, %ecx /* number of nanoseconds in a second */
+ mov %edx, %ebx
+ mul %ecx
+ mov %edx, %edi
+ mov %eax, %esi
+ mov %ebx, %eax
+ mul %ecx
+ add %edi, %eax
+ adc $0, %edx /* result in edx:eax:esi */
+ mov %eax, %edi
+ mov _COMM_PAGE_NT_SHIFT,%ecx /* overloaded as the low 32 tscFreq */
+ xor %eax, %eax
+ xchg %edx, %eax
+ div %ecx
+ xor %eax, %eax
+ mov %edi, %eax
+ div %ecx
+ mov %eax, %ebx
+ mov %esi, %eax
+ div %ecx
+ mov %ebx, %edx /* result in edx:eax */
+ popl %esi /* recover generation */
add _COMM_PAGE_NT_NS_BASE,%eax
adc _COMM_PAGE_NT_NS_BASE+4,%edx
- cmp _COMM_PAGE_NT_TSC_BASE,%esi
- jne 0b
- cmp _COMM_PAGE_NT_TSC_BASE+4,%edi
- jne 0b
+ cmpl _COMM_PAGE_NT_GENERATION,%esi /* have the parameters changed? */
+ jne 0b /* yes, loop until stable */
pop %ebx
pop %edi
pop %esi
pop %ebp
- ret
+ ret /* result in edx:eax */
- COMMPAGE_DESCRIPTOR(nanotime,_COMM_PAGE_NANOTIME,0,0)
- COMMPAGE_DESCRIPTOR(old_nanotime,_COMM_PAGE_OLD_NANOTIME,0,0)
+ COMMPAGE_DESCRIPTOR(nanotime_slow,_COMM_PAGE_NANOTIME,kSlow,0)
/* The 64-bit version. We return the 64-bit nanotime in %rax,
.text
.align 2
.code64
-Lold_nanotime_64:
-Lnanotime_64: // NB: must preserve r9, r10, and r11
- pushq %rbp // set up a frame for backtraces
+Lnanotime_64: // NB: must preserve r9, r10, and r11
+ pushq %rbp // set up a frame for backtraces
movq %rsp,%rbp
- movq $_COMM_PAGE_32_TO_64(_COMM_PAGE_NT_TSC_BASE),%rsi
+ movq $_COMM_PAGE_32_TO_64(_COMM_PAGE_TIME_DATA_START),%rsi
1:
- movq _NT_TSC_BASE(%rsi),%r8 // r8 := base_tsc
- rdtsc // edx:eax := tsc
- shlq $32,%rdx // rax := ((edx << 32) | eax), ie 64-bit tsc
+ movl _NT_GENERATION(%rsi),%r8d // get generation
+ testl %r8d,%r8d // if 0, data is being changed...
+ jz 1b // ...so loop until stable
+ lfence
+ rdtsc // edx:eax := tsc
+ lfence
+ shlq $32,%rdx // rax := ((edx << 32) | eax), ie 64-bit tsc
orq %rdx,%rax
- subq %r8, %rax // rax := (tsc - base_tsc)
+ subq _NT_TSC_BASE(%rsi), %rax // rax := (tsc - base_tsc)
movl _NT_SCALE(%rsi),%ecx
- mulq %rcx // rdx:rax := (tsc - base_tsc) * scale
- shrdq $32,%rdx,%rax // _COMM_PAGE_NT_SHIFT is always 32
- addq _NT_NS_BASE(%rsi),%rax // (((tsc - base_tsc) * scale) >> 32) + ns_base
+ mulq %rcx // rdx:rax := (tsc - base_tsc) * scale
+ shrdq $32,%rdx,%rax // _COMM_PAGE_NT_SHIFT is always 32
+ addq _NT_NS_BASE(%rsi),%rax // (((tsc - base_tsc) * scale) >> 32) + ns_base
- cmpq _NT_TSC_BASE(%rsi),%r8 // did the data change during computation?
+ cmpl _NT_GENERATION(%rsi),%r8d // did the data change during computation?
jne 1b
popq %rbp
ret
- COMMPAGE_DESCRIPTOR(nanotime_64,_COMM_PAGE_NANOTIME,0,0)
- COMMPAGE_DESCRIPTOR(old_nanotime_64,_COMM_PAGE_OLD_NANOTIME,0,0)
+ COMMPAGE_DESCRIPTOR(nanotime_64,_COMM_PAGE_NANOTIME,0,kSlow)
projects / apple / xnu.git / blobdiff