]> git.saurik.com Git - apple/xnu.git/blobdiff - osfmk/i386/idt.s
xnu-1699.26.8.tar.gz
[apple/xnu.git] / osfmk / i386 / idt.s
index e68a8f4fdfac82e348f3861542bb39df2bfc3e3a..362b783a463621d8a23b5397088d4dc1cee7e5ac 100644 (file)
@@ -1,23 +1,29 @@
 /*
- * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2000-2010 Apple Inc. All rights reserved.
  *
- * @APPLE_LICENSE_HEADER_START@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
- * The contents of this file constitute Original Code as defined in and
- * are subject to the Apple Public Source License Version 1.1 (the
- * "License").  You may not use this file except in compliance with the
- * License.  Please obtain a copy of the License at
- * http://www.apple.com/publicsource and read it before using this file.
+ * 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.
  * 
- * This Original Code and all software distributed under the License are
- * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * 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 OR NON-INFRINGEMENT.  Please see the
- * License for the specific language governing rights and limitations
- * under the License.
+ * 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_LICENSE_HEADER_END@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 /*
  * @OSF_COPYRIGHT@
 #include <i386/asm.h>
 #include <assym.s>
 #include <mach_kdb.h>
+#include <i386/eflags.h>
+#include <i386/trap.h>
+#include <i386/rtclock_asm.h>
+#define _ARCH_I386_ASM_HELP_H_  /* Prevent inclusion of user header */
+#include <mach/i386/syscall_sw.h>
+#include <i386/postcode.h>
+#include <i386/proc_reg.h>
+#include <mach/exception_types.h>
+
+/*
+ * Low-memory handlers.
+ */
+#define        LO_ALLINTRS             EXT(lo_allintrs32)
+#define        LO_ALLTRAPS             EXT(lo_alltraps32)
+#define        LO_SYSENTER             EXT(lo_sysenter32)
+#define        LO_UNIX_SCALL           EXT(lo_unix_scall32)
+#define        LO_MACH_SCALL           EXT(lo_mach_scall32)
+#define        LO_MDEP_SCALL           EXT(lo_mdep_scall32)
+#define        LO_DIAG_SCALL           EXT(lo_diag_scall32)
+
+
+#define HI_DATA(lo_addr)       ( (EXT(lo_addr) - EXT(hi_remap_data)) + HIGH_IDT_BASE )
+#define HI_TEXT(lo_text)       ( (EXT(lo_text) - EXT(hi_remap_text)) + HIGH_MEM_BASE )
 
 /*
  * Interrupt descriptor table and code vectors for it.
  */
 #define        IDT_BASE_ENTRY(vec,seg,type) \
        .data                   ;\
-       .long   vec             ;\
+       .long   EXT(vec) - EXT(hi_remap_text) + HIGH_MEM_BASE ; \
        .word   seg             ;\
        .byte   0               ;\
        .byte   type            ;\
        .text
 
-#define        IDT_ENTRY(vec,type)     IDT_BASE_ENTRY(vec,KERNEL_CS,type)
+#define        IDT_BASE_ENTRY_INT(vec,seg,type) \
+       .data                   ;\
+       .long   vec - EXT(hi_remap_text) + HIGH_MEM_BASE ; \
+       .word   seg             ;\
+       .byte   0               ;\
+       .byte   type            ;\
+       .text
+
+#define        IDT_BASE_ENTRY_TG(vec,seg,type) \
+       .data                   ;\
+       .long   0               ; \
+       .word   seg             ;\
+       .byte   0               ;\
+       .byte   type            ;\
+       .text
+
+#define        IDT_ENTRY(vec,type)     IDT_BASE_ENTRY(vec,KERNEL32_CS,type)
+#define        IDT_ENTRY_INT(vec,type) IDT_BASE_ENTRY_INT(vec,KERNEL32_CS,type)
 
 /*
  * No error code.  Clear error code and push trap number.
  */
 #define        EXCEPTION(n,name) \
-       IDT_ENTRY(EXT(name),K_TRAP_GATE);\
+       IDT_ENTRY(name,K_INTR_GATE);\
 Entry(name)                            ;\
        pushl   $0                      ;\
        pushl   $(n)                    ;\
-       jmp     EXT(alltraps)
+       pusha                           ;\
+       movl    $(LO_ALLTRAPS),%ebx     ;\
+       jmp     enter_lohandler
 
+       
 /*
  * Interrupt from user.  Clear error code and push trap number.
  */
 #define        EXCEP_USR(n,name) \
-       IDT_ENTRY(EXT(name),U_TRAP_GATE);\
+       IDT_ENTRY(name,U_INTR_GATE);\
 Entry(name)                            ;\
        pushl   $0                      ;\
        pushl   $(n)                    ;\
-       jmp     EXT(alltraps)
+       pusha                           ;\
+       movl    $(LO_ALLTRAPS),%ebx     ;\
+       jmp     enter_lohandler
+       
 
 /*
  * Special interrupt code.
  */
 #define        EXCEP_SPC(n,name)  \
-       IDT_ENTRY(EXT(name),K_TRAP_GATE)
-
+       IDT_ENTRY(name,K_INTR_GATE) 
+       
 /*
  * Special interrupt code from user.
  */
 #define EXCEP_SPC_USR(n,name)  \
-       IDT_ENTRY(EXT(name),U_TRAP_GATE)
+       IDT_ENTRY(name,U_INTR_GATE) 
+
 
 /*
  * Extra-special interrupt code.  Note that no offset may be
  * specified in a task gate descriptor, so name is ignored.
  */
 #define        EXCEP_TASK(n,name)  \
-       IDT_BASE_ENTRY(0,DEBUG_TSS,K_TASK_GATE)
+       IDT_BASE_ENTRY_TG(0,DEBUG_TSS,K_TASK_GATE)
+
+/* Double-fault fatal handler */
+#define DF_FATAL_TASK(n,name)  \
+       IDT_BASE_ENTRY_TG(0,DF_TSS,K_TASK_GATE)
+
+/* machine-check handler */
+#define MC_FATAL_TASK(n,name)  \
+       IDT_BASE_ENTRY_TG(0,MC_TSS,K_TASK_GATE)
 
 /*
  * Error code has been pushed.  Push trap number.
  */
 #define        EXCEP_ERR(n,name) \
-       IDT_ENTRY(EXT(name),K_TRAP_GATE);\
-Entry(name)                            ;\
-       pushl   $(n)                    ;\
-       jmp     EXT(alltraps)
+       IDT_ENTRY(name,K_INTR_GATE)             ;\
+Entry(name)                                    ;\
+       pushl   $(n)                            ;\
+       pusha                                   ;\
+       movl    $(LO_ALLTRAPS),%ebx             ;\
+       jmp     enter_lohandler
 
+       
 /*
  * Interrupt.
  */
 #define        INTERRUPT(n) \
-       IDT_ENTRY(0f,K_INTR_GATE)       ;\
-0:                                     ;\
-       pushl   %eax                    ;\
-       movl    $(n),%eax               ;\
-       jmp     EXT(all_intrs)
+       IDT_ENTRY_INT(L_ ## n,K_INTR_GATE)      ;\
+       .align FALIGN                           ;\
+L_ ## n:                                       ;\
+       pushl   $0                              ;\
+       pushl   $(n)                            ;\
+       pusha                                   ;\
+       movl    $(LO_ALLINTRS),%ebx             ;\
+       jmp     enter_lohandler
+
 
        .data
-Entry(idt)
+       .align 12
+Entry(master_idt)
+Entry(hi_remap_data)
        .text
+       .align 12
+Entry(hi_remap_text)
 
 EXCEPTION(0x00,t_zero_div)
-EXCEP_SPC(0x01,t_debug)
+EXCEP_SPC(0x01,hi_debug)
 INTERRUPT(0x02)                        /* NMI */
 EXCEP_USR(0x03,t_int3)
 EXCEP_USR(0x04,t_into)
@@ -139,23 +211,23 @@ EXCEPTION(0x07,t_nofpu)
 #if    MACH_KDB
 EXCEP_TASK(0x08,db_task_dbl_fault)
 #else
-EXCEPTION(0x08,a_dbl_fault)
+DF_FATAL_TASK(0x08,df_task_start)
 #endif
 EXCEPTION(0x09,a_fpu_over)
 EXCEPTION(0x0a,a_inv_tss)
-EXCEP_SPC(0x0b,t_segnp)
+EXCEP_SPC(0x0b,hi_segnp)
 #if    MACH_KDB
 EXCEP_TASK(0x0c,db_task_stk_fault)
 #else
 EXCEP_ERR(0x0c,t_stack_fault)
 #endif
-EXCEP_SPC(0x0d,t_gen_prot)
-EXCEP_SPC(0x0e,t_page_fault)
+EXCEP_SPC(0x0d,hi_gen_prot)
+EXCEP_SPC(0x0e,hi_page_fault)
 EXCEPTION(0x0f,t_trap_0f)
 EXCEPTION(0x10,t_fpu_err)
 EXCEPTION(0x11,t_trap_11)
-EXCEPTION(0x12,t_trap_12)
-EXCEPTION(0x13,t_trap_13)
+MC_FATAL_TASK(0x12,mc_task_start)
+EXCEPTION(0x13,t_sse_err)
 EXCEPTION(0x14,t_trap_14)
 EXCEPTION(0x15,t_trap_15)
 EXCEPTION(0x16,t_trap_16)
@@ -269,12 +341,13 @@ INTERRUPT(0x7b)
 INTERRUPT(0x7c)
 INTERRUPT(0x7d)
 INTERRUPT(0x7e)
-INTERRUPT(0x7f)
+EXCEP_USR(0x7f, t_dtrace_ret)
+
+EXCEP_SPC_USR(0x80,hi_unix_scall)
+EXCEP_SPC_USR(0x81,hi_mach_scall)
+EXCEP_SPC_USR(0x82,hi_mdep_scall)
+EXCEP_SPC_USR(0x83,hi_diag_scall)
 
-EXCEP_SPC_USR(0x80,syscall_int80)
-INTERRUPT(0x81)
-INTERRUPT(0x82)
-INTERRUPT(0x83)
 INTERRUPT(0x84)
 INTERRUPT(0x85)
 INTERRUPT(0x86)
@@ -407,3 +480,856 @@ INTERRUPT(0xfd)
 INTERRUPT(0xfe)
 EXCEPTION(0xff,t_preempt)
 
+
+       .data
+Entry(lo_kernel_cr3)
+       .long 0
+       .long 0
+       
+        .text
+
+       
+/*
+ * Trap/interrupt entry points.
+ *
+ * All traps must create the following save area on the PCB "stack":
+ *
+ *     gs
+ *     fs
+ *     es
+ *     ds
+ *     edi
+ *     esi
+ *     ebp
+ *     cr2 if page fault - otherwise unused
+ *     ebx
+ *     edx
+ *     ecx
+ *     eax
+ *     trap number
+ *     error code
+ *     eip
+ *     cs
+ *     eflags
+ *     user esp - if from user
+ *     user ss  - if from user
+ */
+
+ret_to_kernel:
+       jmp *1f
+1:     .long HI_TEXT(hi_ret_to_kernel)
+
+ret_to_user:
+       jmp *1f
+1:     .long HI_TEXT(hi_ret_to_user) 
+
+Entry(hi_ret_to_user)
+       movl    %esp,%ebx
+       movl    %gs:CPU_ACTIVE_THREAD,%ecx
+       subl    TH_PCB_ISS(%ecx),%ebx
+       movl    $(WINDOWS_CLEAN),TH_COPYIO_STATE(%ecx)
+
+       movl    TH_PCB_IDS(%ecx),%eax   /* get debug state struct */
+       cmpl    $0,%eax                 /* is there a debug state */
+       je      1f                      /* branch if not */
+       movl    DS_DR0(%eax), %ecx      /* Load the 32 bit debug registers */
+       movl    %ecx, %db0
+       movl    DS_DR1(%eax), %ecx
+       movl    %ecx, %db1
+       movl    DS_DR2(%eax), %ecx
+       movl    %ecx, %db2
+       movl    DS_DR3(%eax), %ecx
+       movl    %ecx, %db3
+       movl    DS_DR7(%eax), %eax
+1:
+       addl    %gs:CPU_HI_ISS,%ebx     /* rebase PCB save area to high addr */
+       movl    %gs:CPU_TASK_CR3,%ecx
+       movl    %ecx,%gs:CPU_ACTIVE_CR3
+       movl    %ebx,%esp               /* switch to hi based PCB stack */
+       movl    %ecx,%cr3               /* switch to user's address space */
+
+       cmpl    $0,%eax                 /* is dr7 set to something? */
+       je      2f                      /* branch if not */
+       movl    %eax,%db7               /* Set dr7 */
+2:
+
+Entry(hi_ret_to_kernel)
+
+       popl    %eax                    /* ignore flavor of saved state */
+EXT(ret_popl_gs):
+       popl    %gs                     /* restore segment registers */
+EXT(ret_popl_fs):
+       popl    %fs
+EXT(ret_popl_es):
+       popl    %es
+EXT(ret_popl_ds):      
+       popl    %ds
+
+        popa                            /* restore general registers */
+        addl    $8,%esp                 /* discard trap number and error code */
+
+        cmpl    $(SYSENTER_CS),4(%esp)  /* test for fast entry/exit */
+        je      fast_exit
+EXT(ret_iret):
+        iret                            /* return from interrupt */
+fast_exit:
+       popl    %edx                    /* user return eip */
+       popl    %ecx                    /* pop and toss cs */
+       andl    $(~EFL_IF),(%esp)       /* clear intrs enabled, see sti below */
+       popf                            /* flags - carry denotes failure */
+       popl    %ecx                    /* user return esp */
+       sti                             /* interrupts enabled after sysexit */
+       sysexit
+
+               
+Entry(hi_unix_scall)
+       pushl   %eax                    /* save system call number */
+        pushl   $0                      /* clear trap number slot */
+        pusha                           /* save the general registers */
+       movl    $(LO_UNIX_SCALL),%ebx
+       jmp     enter_lohandler
+
+       
+Entry(hi_mach_scall)
+       pushl   %eax                    /* save system call number */
+        pushl   $0                      /* clear trap number slot */
+        pusha                           /* save the general registers */
+       movl    $(LO_MACH_SCALL),%ebx
+       jmp     enter_lohandler
+
+       
+Entry(hi_mdep_scall)
+       pushl   %eax                    /* save system call number */
+        pushl   $0                      /* clear trap number slot */
+        pusha                           /* save the general registers */
+       movl    $(LO_MDEP_SCALL),%ebx
+       jmp     enter_lohandler
+
+       
+Entry(hi_diag_scall)
+       pushl   %eax                    // Save sselector
+        pushl   $0                      // Clear trap number slot
+        pusha                           // save the general registers
+       movl    $(LO_DIAG_SCALL),%ebx   // Get the function down low to transfer to
+       jmp     enter_lohandler                 // Leap to it...
+
+       
+/*
+ * sysenter entry point
+ * Requires user code to set up:
+ *     edx: user instruction pointer (return address)
+ *     ecx: user stack pointer
+ *             on which is pushed stub ret addr and saved ebx
+ * Return to user-space is made using sysexit.
+ * Note: sysenter/sysexit cannot be used for calls returning a value in edx,
+ *       or requiring ecx to be preserved.
+ */
+Entry(hi_sysenter)
+       movl    (%esp), %esp            /* switch from intr stack to pcb */
+       /*
+        * Push values on to the PCB stack
+        * to cons up the saved state.
+        */
+       pushl   $(USER_DS)              /* ss */
+       pushl   %ecx                    /* uesp */
+       pushf                           /* flags */
+       /*
+       * Clear, among others, the Nested Task (NT) flags bit;
+       * This is cleared by INT, but not by SYSENTER.
+       */
+       pushl   $0
+       popfl
+       pushl   $(SYSENTER_CS)          /* cs */
+hi_sysenter_2:
+       pushl   %edx                    /* eip */
+       pushl   %eax                    /* err/eax - syscall code */
+       pushl   $0                      /* clear trap number slot */
+       pusha                           /* save the general registers */
+       orl     $(EFL_IF),R32_EFLAGS-R32_EDI(%esp)      /* (edi was last reg pushed) */
+       movl    $(LO_SYSENTER),%ebx
+enter_lohandler:
+       pushl   %ds
+       pushl   %es
+        pushl   %fs
+        pushl   %gs
+       pushl   $(SS_32)                /* 32-bit state flavor */
+enter_lohandler1:
+       mov     %ss,%eax
+       mov     %eax,%ds
+       mov     %eax,%fs
+       mov     %eax,%es                /* switch to kernel data seg */
+       mov     $(CPU_DATA_GS),%eax
+       mov     %eax,%gs
+       cld                             /* clear direction flag */
+       /*
+        * Switch to kernel's address space if necessary
+        */
+       movl    HI_DATA(lo_kernel_cr3),%ecx
+       movl    %cr3,%eax
+       cmpl    %eax,%ecx
+       je      1f
+       movl    %ecx,%cr3
+       movl    %ecx,%gs:CPU_ACTIVE_CR3
+1:
+       testb   $3,R32_CS(%esp)
+       jz      2f
+       movl    %esp,%edx                       /* came from user mode */
+       xor     %ebp, %ebp
+       subl    %gs:CPU_HI_ISS,%edx
+       movl    %gs:CPU_ACTIVE_THREAD,%ecx
+       addl    TH_PCB_ISS(%ecx),%edx           /* rebase the high stack to a low address */
+       movl    %edx,%esp
+       cmpl    $0, TH_PCB_IDS(%ecx)    /* Is there a debug register state? */
+       je      2f
+       movl    $0, %ecx                /* If so, reset DR7 (the control) */
+       movl    %ecx, %dr7
+2:
+       movl    R32_TRAPNO(%esp),%ecx                   // Get the interrupt vector
+       addl    $1,%gs:hwIntCnt(,%ecx,4)        // Bump the count
+       jmp             *%ebx
+
+       
+/*
+ * Page fault traps save cr2.
+ */
+Entry(hi_page_fault)
+       pushl   $(T_PAGE_FAULT)         /* mark a page fault trap */
+       pusha                           /* save the general registers */
+       movl    %cr2,%eax               /* get the faulting address */
+       movl    %eax,R32_CR2-R32_EDI(%esp)/* save in esp save slot */
+
+       movl    $(LO_ALLTRAPS),%ebx
+       jmp     enter_lohandler
+
+
+
+/*
+ * Debug trap.  Check for single-stepping across system call into
+ * kernel.  If this is the case, taking the debug trap has turned
+ * off single-stepping - save the flags register with the trace
+ * bit set.
+ */
+Entry(hi_debug)
+       testb   $3,4(%esp)
+       jnz     hi_debug_trap
+                                       /* trap came from kernel mode */
+       cmpl    $(HI_TEXT(hi_mach_scall)),(%esp)
+       jne     6f
+       addl    $12,%esp                /* remove eip/cs/eflags from debug_trap */
+       jmp     EXT(hi_mach_scall)      /* continue system call entry */
+6:
+       cmpl    $(HI_TEXT(hi_mdep_scall)),(%esp)
+       jne     5f
+       addl    $12,%esp                /* remove eip/cs/eflags from debug_trap */
+       jmp     EXT(hi_mdep_scall)      /* continue system call entry */
+5:
+       cmpl    $(HI_TEXT(hi_unix_scall)),(%esp)
+       jne     4f
+       addl    $12,%esp                /* remove eip/cs/eflags from debug_trap */
+       jmp     EXT(hi_unix_scall)      /* continue system call entry */
+4:
+       cmpl    $(HI_TEXT(hi_sysenter)),(%esp)
+       jne     hi_debug_trap
+       /*
+        * eip/cs/flags have been pushed on intr stack
+        * We have to switch to pcb stack and copy eflags.
+        * Note: setting the cs selector to SYSENTER_TF_CS
+        * will cause the return to user path to take the iret path so
+        * that eflags (containing the trap bit) is set atomically.
+        * In unix_syscall this is tested so that we'll rewind the pc
+        * to account for with sysenter or int entry.
+        */ 
+       addl    $8,%esp                 /* remove eip/cs */
+       pushl   %ecx                    /* save %ecx */
+       movl    8(%esp),%ecx            /* top of intr stack -> pcb stack */
+       xchgl   %ecx,%esp               /* switch to pcb stack */
+       pushl   $(USER_DS)              /* ss */
+       pushl   %ss:(%ecx)              /* %ecx into uesp slot */
+       pushl   %ss:4(%ecx)             /* eflags */
+       movl    %ss:(%ecx),%ecx         /* restore %ecx */
+       pushl   $(SYSENTER_TF_CS)       /* cs - not SYSENTER_CS for iret path */
+       jmp     hi_sysenter_2           /* continue sysenter entry */
+hi_debug_trap:
+       pushl   $0
+       pushl   $(T_DEBUG)              /* handle as user trap */
+       pusha                           /* save the general registers */
+       movl    $(LO_ALLTRAPS),%ebx
+       jmp     enter_lohandler 
+
+
+
+/*
+ * General protection or segment-not-present fault.
+ * Check for a GP/NP fault in the kernel_return
+ * sequence; if there, report it as a GP/NP fault on the user's instruction.
+ *
+ * esp->     0:        trap code (NP or GP)
+ *          4: segment number in error
+ *          8  eip
+ *         12  cs
+ *         16  eflags 
+ *         20  old registers (trap is from kernel)
+ */
+Entry(hi_gen_prot)
+       pushl   $(T_GENERAL_PROTECTION) /* indicate fault type */
+       jmp     trap_check_kernel_exit  /* check for kernel exit sequence */
+
+Entry(hi_segnp)
+       pushl   $(T_SEGMENT_NOT_PRESENT)
+                                       /* indicate fault type */
+trap_check_kernel_exit:
+       testb   $3,12(%esp)
+       jnz     hi_take_trap
+                                       /* trap was from kernel mode, so */
+                                       /* check for the kernel exit sequence */
+       cmpl    $(HI_TEXT(ret_iret)),8(%esp)    /* on IRET? */
+       je      fault_iret
+       cmpl    $(HI_TEXT(ret_popl_ds)),8(%esp) /* popping DS? */
+       je      fault_popl_ds
+       cmpl    $(HI_TEXT(ret_popl_es)),8(%esp) /* popping ES? */
+       je      fault_popl_es
+       cmpl    $(HI_TEXT(ret_popl_fs)),8(%esp) /* popping FS? */
+       je      fault_popl_fs
+       cmpl    $(HI_TEXT(ret_popl_gs)),8(%esp) /* popping GS? */
+       je      fault_popl_gs
+hi_take_trap:
+       pusha                           /* save the general registers */
+       movl    $(LO_ALLTRAPS),%ebx
+       jmp     enter_lohandler
+
+               
+/*
+ * GP/NP fault on IRET: CS or SS is in error.
+ * All registers contain the user's values.
+ *
+ * on SP is
+ *  0  trap number
+ *  4  errcode
+ *  8  eip
+ * 12  cs              --> trapno
+ * 16  efl             --> errcode
+ * 20  user eip
+ * 24  user cs
+ * 28  user eflags
+ * 32  user esp
+ * 36  user ss
+ */
+fault_iret:
+       movl    %eax,8(%esp)            /* save eax (we don`t need saved eip) */
+       popl    %eax                    /* get trap number */
+       movl    %eax,12-4(%esp)         /* put in user trap number */
+       popl    %eax                    /* get error code */
+       movl    %eax,16-8(%esp)         /* put in user errcode */
+       popl    %eax                    /* restore eax */
+                                       /* now treat as fault from user */
+       pusha                           /* save the general registers */
+       movl    $(LO_ALLTRAPS),%ebx
+       jmp     enter_lohandler
+
+/*
+ * Fault restoring a segment register.  The user's registers are still
+ * saved on the stack.  The offending segment register has not been
+ * popped.
+ */
+fault_popl_ds:
+       popl    %eax                    /* get trap number */
+       popl    %edx                    /* get error code */
+       addl    $12,%esp                /* pop stack to user regs */
+       jmp     push_es                 /* (DS on top of stack) */
+fault_popl_es:
+       popl    %eax                    /* get trap number */
+       popl    %edx                    /* get error code */
+       addl    $12,%esp                /* pop stack to user regs */
+       jmp     push_fs                 /* (ES on top of stack) */
+fault_popl_fs:
+       popl    %eax                    /* get trap number */
+       popl    %edx                    /* get error code */
+       addl    $12,%esp                /* pop stack to user regs */
+       jmp     push_gs                 /* (FS on top of stack) */
+fault_popl_gs:
+       popl    %eax                    /* get trap number */
+       popl    %edx                    /* get error code */
+       addl    $12,%esp                /* pop stack to user regs */
+       jmp     push_none               /* (GS on top of stack) */
+
+push_es:
+       pushl   %es                     /* restore es, */
+push_fs:
+       pushl   %fs                     /* restore fs, */
+push_gs:
+       pushl   %gs                     /* restore gs. */
+push_none:
+       pushl   $(SS_32)                /* 32-bit state flavor */
+       movl    %eax,R32_TRAPNO(%esp)   /* set trap number */
+       movl    %edx,R32_ERR(%esp)      /* set error code */
+                                       /* now treat as fault from user */
+                                       /* except that segment registers are */
+                                       /* already pushed */
+       movl    $(LO_ALLTRAPS),%ebx
+       jmp     enter_lohandler1
+
+       
+        .text
+
+
+Entry(hi_remap_etext)
+
+
+/*
+ * All 32 bit task 'exceptions' enter lo_alltraps:
+ *     esp     -> x86_saved_state_t
+ * 
+ * The rest of the state is set up as: 
+ *     cr3      -> kernel directory
+ *     esp      -> low based stack
+ *     gs       -> CPU_DATA_GS
+ *     cs       -> KERNEL32_CS
+ *     ss/ds/es -> KERNEL_DS
+ *
+ *     interrupts disabled
+ *     direction flag cleared
+ */
+Entry(lo_alltraps32)
+       movl    R32_CS(%esp),%eax       /* assume 32-bit state */
+       cmpl    $(SS_64),SS_FLAVOR(%esp)/* 64-bit? */   
+       jne     1f
+       movl    R64_CS(%esp),%eax       /* 64-bit user mode */
+1:
+       testb   $3,%al
+       jz      trap_from_kernel
+                                               /* user mode trap */
+       TIME_TRAP_UENTRY
+
+       movl    %gs:CPU_ACTIVE_THREAD,%ecx
+       movl    TH_TASK(%ecx),%ebx
+
+       /* Check for active vtimers in the current task */
+       TASK_VTIMER_CHECK(%ebx, %ecx)
+
+       movl    %gs:CPU_KERNEL_STACK,%ebx
+       xchgl   %ebx,%esp               /* switch to kernel stack */
+
+       CCALL1(user_trap, %ebx)         /* call user trap routine */
+       /* user_trap() unmasks interrupts */
+       cli                             /* hold off intrs - critical section */
+       xorl    %ecx,%ecx               /* don't check if we're in the PFZ */
+       
+/*
+ * Return from trap or system call, checking for ASTs.
+ * On lowbase PCB stack with intrs disabled
+ */    
+Entry(return_from_trap32)
+       movl    %gs:CPU_ACTIVE_THREAD, %esp
+       movl    TH_PCB_ISS(%esp), %esp  /* switch back to PCB stack */
+       movl    %gs:CPU_PENDING_AST, %eax
+       testl   %eax, %eax
+       je      EXT(return_to_user)     /* branch if no AST */
+LEXT(return_from_trap_with_ast)
+       movl    %gs:CPU_KERNEL_STACK, %ebx
+       xchgl   %ebx, %esp              /* switch to kernel stack */
+
+       testl   %ecx, %ecx              /* see if we need to check for an EIP in the PFZ */
+       je      2f                      /* no, go handle the AST */
+       cmpl    $(SS_64), SS_FLAVOR(%ebx)       /* are we a 64-bit task? */
+       je      1f
+                                       /* no... 32-bit user mode */
+       movl    R32_EIP(%ebx), %eax
+       pushl   %ebx                    /* save PCB stack */
+       xorl    %ebp, %ebp              /* clear frame pointer */
+       CCALL1(commpage_is_in_pfz32, %eax)
+       popl    %ebx                    /* retrieve pointer to PCB stack */
+       testl   %eax, %eax
+       je      2f                      /* not in the PFZ... go service AST */
+       movl    %eax, R32_EBX(%ebx)     /* let the PFZ know we've pended an AST */
+       xchgl   %ebx, %esp              /* switch back to PCB stack */
+       jmp     EXT(return_to_user)
+1:                                     /* 64-bit user mode */
+       movl    R64_RIP(%ebx), %ecx
+       movl    R64_RIP+4(%ebx), %eax
+       pushl   %ebx                    /* save PCB stack */
+       xorl    %ebp, %ebp              /* clear frame pointer */
+       CCALL2(commpage_is_in_pfz64, %ecx, %eax)
+       popl    %ebx                    /* retrieve pointer to PCB stack */
+       testl   %eax, %eax              
+       je      2f                      /* not in the PFZ... go service AST */
+       movl    %eax, R64_RBX(%ebx)     /* let the PFZ know we've pended an AST */
+       xchgl   %ebx, %esp              /* switch back to PCB stack */
+       jmp     EXT(return_to_user)
+2:     
+       sti                             /* interrupts always enabled on return to user mode */
+       xorl    %ebp, %ebp              /* Clear framepointer */
+       CCALL1(i386_astintr, $0)        /* take the AST */
+       cli
+       xorl    %ecx, %ecx              /* don't check if we're in the PFZ */
+       jmp     EXT(return_from_trap32) /* and check again (rare) */
+
+
+/*
+ * Trap from kernel mode.  No need to switch stacks.
+ * Interrupts must be off here - we will set them to state at time of trap
+ * as soon as it's safe for us to do so and not recurse doing preemption
+ */
+trap_from_kernel:
+       movl    %esp, %eax              /* saved state addr */
+       pushl   R32_EIP(%esp)           /* Simulate a CALL from fault point */
+       pushl   %ebp                    /* Extend framepointer chain */
+       movl    %esp, %ebp
+       CCALL1WITHSP(kernel_trap, %eax) /* Call kernel trap handler */
+       popl    %ebp
+       addl    $4, %esp
+       cli
+
+       movl    %gs:CPU_PENDING_AST,%eax                /* get pending asts */
+       testl   $ AST_URGENT,%eax       /* any urgent preemption? */
+       je      ret_to_kernel                   /* no, nothing to do */
+       cmpl    $ T_PREEMPT,R32_TRAPNO(%esp)
+       je      ret_to_kernel                     /* T_PREEMPT handled in kernel_trap() */
+       testl   $ EFL_IF,R32_EFLAGS(%esp)               /* interrupts disabled? */
+       je      ret_to_kernel
+       cmpl    $0,%gs:CPU_PREEMPTION_LEVEL             /* preemption disabled? */
+       jne     ret_to_kernel
+       movl    %gs:CPU_KERNEL_STACK,%eax
+       movl    %esp,%ecx
+       xorl    %eax,%ecx
+       and     EXT(kernel_stack_mask),%ecx
+       testl   %ecx,%ecx               /* are we on the kernel stack? */
+       jne     ret_to_kernel           /* no, skip it */
+
+       CCALL1(i386_astintr, $1)        /* take the AST */
+
+       jmp     ret_to_kernel
+
+
+/*
+ * All interrupts on all tasks enter here with:
+ *     esp->    -> x86_saved_state_t
+ *
+ *     cr3      -> kernel directory
+ *     esp      -> low based stack
+ *     gs       -> CPU_DATA_GS
+ *     cs       -> KERNEL32_CS
+ *     ss/ds/es -> KERNEL_DS
+ *
+ *     interrupts disabled
+ *     direction flag cleared
+ */
+Entry(lo_allintrs32)
+       /*
+        * test whether already on interrupt stack
+        */
+       movl    %gs:CPU_INT_STACK_TOP,%ecx
+       cmpl    %esp,%ecx
+       jb      1f
+       leal    -INTSTACK_SIZE(%ecx),%edx
+       cmpl    %esp,%edx
+       jb      int_from_intstack
+1:     
+       xchgl   %ecx,%esp               /* switch to interrupt stack */
+
+       movl    %cr0,%eax               /* get cr0 */
+       orl     $(CR0_TS),%eax          /* or in TS bit */
+       movl    %eax,%cr0               /* set cr0 */
+
+       subl    $8, %esp                /* for 16-byte stack alignment */
+       pushl   %ecx                    /* save pointer to old stack */
+       movl    %ecx,%gs:CPU_INT_STATE  /* save intr state */
+       
+       TIME_INT_ENTRY                  /* do timing */
+
+       movl    %gs:CPU_ACTIVE_THREAD,%ecx
+       movl    TH_TASK(%ecx),%ebx
+
+       /* Check for active vtimers in the current task */
+       TASK_VTIMER_CHECK(%ebx, %ecx)
+
+       incl    %gs:CPU_PREEMPTION_LEVEL
+       incl    %gs:CPU_INTERRUPT_LEVEL
+
+       movl    %gs:CPU_INT_STATE, %eax
+       CCALL1(interrupt, %eax)         /* call generic interrupt routine */
+
+       cli                             /* just in case we returned with intrs enabled */
+       xorl    %eax,%eax
+       movl    %eax,%gs:CPU_INT_STATE  /* clear intr state pointer */
+
+       decl    %gs:CPU_INTERRUPT_LEVEL
+       decl    %gs:CPU_PREEMPTION_LEVEL
+
+       TIME_INT_EXIT                   /* do timing */
+
+       movl    %gs:CPU_ACTIVE_THREAD,%eax
+       movl    TH_PCB_FPS(%eax),%eax   /* get pcb's ifps */
+       testl   %eax, %eax              /* Is there a context */
+       je      1f                      /* Branch if not */
+       cmpl    $0, FP_VALID(%eax)      /* Check fp_valid */
+       jne     1f                      /* Branch if valid */
+       clts                            /* Clear TS */
+       jmp     2f
+1:
+       movl    %cr0,%eax               /* get cr0 */
+       orl     $(CR0_TS),%eax          /* or in TS bit */
+       movl    %eax,%cr0               /* set cr0 */
+2:
+       popl    %esp                    /* switch back to old stack */
+
+       /* Load interrupted code segment into %eax */
+       movl    R32_CS(%esp),%eax       /* assume 32-bit state */
+       cmpl    $(SS_64),SS_FLAVOR(%esp)/* 64-bit? */   
+       jne     3f
+       movl    R64_CS(%esp),%eax       /* 64-bit user mode */
+3:
+       testb   $3,%al                  /* user mode, */
+       jnz     ast_from_interrupt_user /* go handle potential ASTs */
+       /*
+        * we only want to handle preemption requests if
+        * the interrupt fell in the kernel context
+        * and preemption isn't disabled
+        */
+       movl    %gs:CPU_PENDING_AST,%eax        
+       testl   $ AST_URGENT,%eax               /* any urgent requests? */
+       je      ret_to_kernel                   /* no, nothing to do */
+
+       cmpl    $0,%gs:CPU_PREEMPTION_LEVEL     /* preemption disabled? */
+       jne     ret_to_kernel                   /* yes, skip it */
+
+       movl    %gs:CPU_KERNEL_STACK,%eax
+       movl    %esp,%ecx
+       xorl    %eax,%ecx
+       and     EXT(kernel_stack_mask),%ecx
+       testl   %ecx,%ecx                       /* are we on the kernel stack? */
+       jne     ret_to_kernel                   /* no, skip it */
+
+       /*
+        * Take an AST from kernel space.  We don't need (and don't want)
+        * to do as much as the case where the interrupt came from user
+        * space.
+        */
+       CCALL1(i386_astintr, $1)
+
+       jmp     ret_to_kernel
+
+
+/*
+ * nested int - simple path, can't preempt etc on way out
+ */
+int_from_intstack:
+       incl    %gs:CPU_PREEMPTION_LEVEL
+       incl    %gs:CPU_INTERRUPT_LEVEL
+
+       movl    %esp, %edx              /* x86_saved_state */
+       CCALL1(interrupt, %edx)
+
+       decl    %gs:CPU_INTERRUPT_LEVEL
+       decl    %gs:CPU_PREEMPTION_LEVEL
+
+       jmp     ret_to_kernel
+
+/*
+ *     Take an AST from an interrupted user
+ */
+ast_from_interrupt_user:
+       movl    %gs:CPU_PENDING_AST,%eax
+       testl   %eax,%eax               /* pending ASTs? */
+       je      ret_to_user             /* no, nothing to do */
+
+       TIME_TRAP_UENTRY
+
+       movl    $1, %ecx                /* check if we're in the PFZ */
+       jmp     EXT(return_from_trap_with_ast)  /* return */
+
+
+/*
+ * 32bit Tasks
+ * System call entries via INTR_GATE or sysenter:
+ *
+ *     esp      -> x86_saved_state32_t
+ *     cr3      -> kernel directory
+ *     esp      -> low based stack
+ *     gs       -> CPU_DATA_GS
+ *     cs       -> KERNEL32_CS
+ *     ss/ds/es -> KERNEL_DS
+ *
+ *     interrupts disabled
+ *     direction flag cleared
+ */
+
+Entry(lo_sysenter32)
+       /*
+        * We can be here either for a mach syscall or a unix syscall,
+        * as indicated by the sign of the code:
+        */
+       movl    R32_EAX(%esp),%eax
+       testl   %eax,%eax
+       js      EXT(lo_mach_scall32)            /* < 0 => mach */
+                                               /* > 0 => unix */
+       
+Entry(lo_unix_scall32)
+       TIME_TRAP_UENTRY
+
+       movl    %gs:CPU_KERNEL_STACK,%edi
+       xchgl   %edi,%esp                       /* switch to kernel stack */
+       movl    %gs:CPU_ACTIVE_THREAD,%ecx      /* get current thread     */
+       movl    TH_TASK(%ecx),%ebx              /* point to current task  */
+       incl    TH_SYSCALLS_UNIX(%ecx)          /* increment call count   */
+
+       /* Check for active vtimers in the current task */
+       TASK_VTIMER_CHECK(%ebx, %ecx)
+
+       sti
+
+       CCALL1(unix_syscall, %edi)
+       /*
+        * always returns through thread_exception_return
+        */
+
+
+Entry(lo_mach_scall32)
+       TIME_TRAP_UENTRY
+
+       movl    %gs:CPU_KERNEL_STACK,%edi
+       xchgl   %edi,%esp                       /* switch to kernel stack */
+       movl    %gs:CPU_ACTIVE_THREAD,%ecx      /* get current thread     */
+       movl    TH_TASK(%ecx),%ebx              /* point to current task  */
+       incl    TH_SYSCALLS_MACH(%ecx)          /* increment call count   */
+
+       /* Check for active vtimers in the current task */
+       TASK_VTIMER_CHECK(%ebx, %ecx)
+
+       sti
+
+       CCALL1(mach_call_munger, %edi)
+       /*
+        * always returns through thread_exception_return
+        */
+
+
+Entry(lo_mdep_scall32)
+       TIME_TRAP_UENTRY
+
+       movl    %gs:CPU_KERNEL_STACK,%edi
+       xchgl   %edi,%esp                       /* switch to kernel stack */
+       movl    %gs:CPU_ACTIVE_THREAD,%ecx      /* get current thread     */
+       movl    TH_TASK(%ecx),%ebx              /* point to current task  */
+
+       /* Check for active vtimers in the current task */
+       TASK_VTIMER_CHECK(%ebx, %ecx)
+       
+       sti
+
+       CCALL1(machdep_syscall, %edi)
+       /*
+        * always returns through thread_exception_return
+        */
+
+
+Entry(lo_diag_scall32)
+       TIME_TRAP_UENTRY
+
+       movl    %gs:CPU_KERNEL_STACK,%edi
+       xchgl   %edi,%esp                       /* switch to kernel stack */
+       movl    %gs:CPU_ACTIVE_THREAD,%ecx      /* get current thread     */
+       movl    TH_TASK(%ecx),%ebx              /* point to current task  */
+
+       /* Check for active vtimers in the current task */
+       TASK_VTIMER_CHECK(%ebx, %ecx)
+
+       pushl   %edi                    /* push pbc stack for later */
+
+       CCALL1(diagCall, %edi)          // Call diagnostics
+       
+       cli                             // Disable interruptions just in case
+       popl    %esp                    // Get back the original stack
+       cmpl    $0,%eax                 // What kind of return is this?
+       jne     EXT(return_to_user)     // Normal return, do not check asts...
+
+       CCALL5(i386_exception, $EXC_SYSCALL, $0x6000, $0, $1, $0)
+               // pass what would be the diag syscall
+               // error return - cause an exception
+       /* no return */
+       
+
+LEXT(return_to_user)
+       TIME_TRAP_UEXIT
+       jmp     ret_to_user
+
+
+/*
+ * Double-fault exception handler task. The last gasp...
+ */
+Entry(df_task_start)
+       CCALL1(panic_double_fault32, $(T_DOUBLE_FAULT))
+       hlt
+
+
+/*
+ * machine-check handler task. The last gasp...
+ */
+Entry(mc_task_start)
+       CCALL1(panic_machine_check32, $(T_MACHINE_CHECK))
+       hlt
+
+#if MACH_KDB
+#include <i386/lapic.h>
+#define CX(addr,reg)   addr(,reg,4)
+#if    0
+/*
+ * Note that the per-fault entry points are not currently
+ * functional.  The only way to make them work would be to
+ * set up separate TSS's for each fault type, which doesn't
+ * currently seem worthwhile.  (The offset part of a task
+ * gate is always ignored.)  So all faults that task switch
+ * currently resume at db_task_start.
+ */
+/*
+ * Double fault (Murphy's point) - error code (0) on stack
+ */
+Entry(db_task_dbl_fault)
+       popl    %eax
+       movl    $(T_DOUBLE_FAULT),%ebx
+       jmp     db_task_start
+/*
+ * Segment not present - error code on stack
+ */
+Entry(db_task_seg_np)
+       popl    %eax
+       movl    $(T_SEGMENT_NOT_PRESENT),%ebx
+       jmp     db_task_start
+/*
+ * Stack fault - error code on (current) stack
+ */
+Entry(db_task_stk_fault)
+       popl    %eax
+       movl    $(T_STACK_FAULT),%ebx
+       jmp     db_task_start
+/*
+ * General protection fault - error code on stack
+ */
+Entry(db_task_gen_prot)
+       popl    %eax
+       movl    $(T_GENERAL_PROTECTION),%ebx
+       jmp     db_task_start
+#endif /* 0 */
+/*
+ * The entry point where execution resumes after last-ditch debugger task
+ * switch.
+ */
+Entry(db_task_start)
+       movl    %esp,%edx
+       subl    $(ISS32_SIZE),%edx
+       movl    %edx,%esp               /* allocate x86_saved_state on stack */
+       movl    %eax,R32_ERR(%esp)
+       movl    %ebx,R32_TRAPNO(%esp)
+       pushl   %edx
+       CPU_NUMBER(%edx)
+       movl    CX(EXT(master_dbtss),%edx),%edx
+       movl    TSS_LINK(%edx),%eax
+       pushl   %eax                    /* pass along selector of previous TSS */
+       call    EXT(db_tss_to_frame)
+       popl    %eax                    /* get rid of TSS selector */
+       call    EXT(db_trap_from_asm)
+       addl    $0x4,%esp
+       /*
+        * And now...?
+        */
+       iret                            /* ha, ha, ha... */
+#endif /* MACH_KDB */