xnu-3248.40.184.tar.gz

[apple/xnu.git] / osfmk / x86_64 / machine_routines_asm.s

diff --git a/osfmk/x86_64/machine_routines_asm.s b/osfmk/x86_64/machine_routines_asm.s
index 0d304f26ad49b8b03d4113a113b41723d52e0c07..af962f2f44238dc46b88b3fe701941950163045e 100644 (file)
--- a/osfmk/x86_64/machine_routines_asm.s
+++ b/osfmk/x86_64/machine_routines_asm.s
@@ -39,9 +39,7 @@
 /*
 **      ml_get_timebase()
 **
-**      Entry   - %rdi contains pointer to 64 bit structure.
-**
-**      Exit    - 64 bit structure filled in.
+**      Returns TSC in RAX
 **
 */
 ENTRY(ml_get_timebase)
@@ -51,7 +49,6 @@ ENTRY(ml_get_timebase)
        lfence
         shlq   $32,%rdx 
         orq    %rdx,%rax
-       movq    %rax, (%rdi)
                        
        ret
 
@@ -81,10 +78,15 @@ ENTRY(ml_get_timebase)
  *
  */
 ENTRY(tmrCvt)
+       cmpq    $1,%rsi                         /* check for unity fastpath */
+       je      1f
        movq    %rdi,%rax
        mulq    %rsi                            /* result is %rdx:%rax */
        shrdq   $32,%rdx,%rax                   /* %rdx:%rax >>= 32 */
        ret
+1:
+       mov     %rdi,%rax
+       ret
 
  /*
  * void _rtc_nanotime_adjust(
@@ -190,45 +192,6 @@ Entry(x86_init_wrapper)
        movq    %rsi, %rsp
        callq   *%rdi
 
-       /*
-       * Generate a 64-bit quantity with possibly random characteristics, intended for use
-       * before the kernel entropy pool is available. The processor's RNG is used if
-       * available, and a value derived from the Time Stamp Counter is returned if not.
-       * Multiple invocations may result in well-correlated values if sourced from the TSC.
-       */
-Entry(ml_early_random)
-       mov     %rbx, %rsi
-       mov     $1, %eax
-       cpuid
-       mov     %rsi, %rbx
-       test    $(1 << 30), %ecx
-       jz      Lnon_rdrand
-       RDRAND_RAX              /* RAX := 64 bits of DRBG entropy */
-       jnc     Lnon_rdrand
-       ret
-Lnon_rdrand:
-       rdtsc /* EDX:EAX := TSC */
-       /* Distribute low order bits */
-       mov     %eax, %ecx
-       xor     %al, %ah
-       shl     $16, %rcx
-       xor     %rcx, %rax
-       xor     %eax, %edx
-
-       /* Incorporate ASLR entropy, if any */
-       lea     (%rip), %rcx
-       shr     $21, %rcx
-       movzbl  %cl, %ecx
-       shl     $16, %ecx
-       xor     %ecx, %edx
-
-       mov     %ah, %cl
-       ror     %cl, %edx /* Right rotate EDX (TSC&0xFF ^ (TSC>>8 & 0xFF))&1F */
-       shl     $32, %rdx
-       xor     %rdx, %rax
-       mov     %cl, %al
-       ret
-       
 #if CONFIG_VMX
 
 /*