osfmk/ppc/mcount.s

   1 /*
   2  * Copyright (c) 2000 Apple Computer, 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 #include <ppc/asm.h>
  29 #include <ppc/proc_reg.h>
  30 #include <assym.s>
  31 #include <debug.h>
  32 #include <mach/ppc/vm_param.h>
  33 #include <ppc/exception.h>
  34
  35
  36 /*
  37  * The compiler generates calls to this function and passes address
  38  * of caller of the function [ from which mcount is called ] as the
  39  * first parameter.
  40  * mcount disables interrupts prior to call mcount() and restores
  41  * interrupt upon return.
  42  * To prevent recursive calls to mcount(), a flag, mcountOff, is set
  43  * in cpu_flags per_proc.
  44  */
  45
  46                         .align 4
  47                         .globl mcount
  48 mcount:
  49                 mflr r0                                                                         ; Load lr
  50                 stw r0,8(r1)                                                            ; Save lr on the stack
  51                 stwu r1,-64(r1)                                                         ; Get a stack frame
  52                 mfmsr   r9                                                                      ; Get msr
  53                 rlwinm  r9,r9,0,MSR_FP_BIT+1,MSR_FP_BIT-1       ; Force floating point off
  54                 rlwinm  r9,r9,0,MSR_VEC_BIT+1,MSR_VEC_BIT-1     ; Force vectors off
  55                 rlwinm  r8,r9,0,MSR_EE_BIT+1,MSR_EE_BIT-1       ; Turn off interruptions
  56                 mtmsr   r8                                                                      ; Update msr
  57                 isync
  58                 mfsprg  r7,1                                                            ; Get the current activation
  59                 lwz             r7,ACT_PER_PROC(r7)                                     ; Get the per_proc block
  60                 lhz             r6,PP_CPU_FLAGS(r7)                                     ; Get  cpu flags
  61                 ori             r5,r6,mcountOff                                         ;
  62                 cmplw   r5,r6                                                           ; is mount off
  63                 beq             mcount_ret                                                      ; return if off
  64                 sth             r5,PP_CPU_FLAGS(r7)                                     ; Update cpu_flags
  65                 stw     r9,FM_ARG0(r1)                                                  ; Save MSR
  66                 mr r4, r0
  67                 bl      _mcount                                                                 ; Call the C routine
  68                 lwz     r9,FM_ARG0(r1)
  69                 mfsprg  r7,1                                                            ; Get the current activation
  70                 lwz             r7,ACT_PER_PROC(r7)                                     ; Get the per_proc block
  71                 lhz             r6,PP_CPU_FLAGS(r7)                                     ; Get CPU number
  72                 li              r5,mcountOff                                            ;
  73                 andc            r6,r6,r5                                                ; Clear mcount_off
  74                 sth             r6,PP_CPU_FLAGS(r7)                                     ; Save cpu_flags
  75 mcount_ret:
  76                 addi r1,r1,64
  77                 mtmsr   r9                                                                      ; Restore MSR
  78                 lwz r0,8(r1)
  79                 mtlr r0
  80                 blr
  81