source: rtems/cpukit/score/cpu/i386/cpu_asm.S @ 38b59a6

/*  cpu_asm.s
 *
 *  This file contains all assembly code for the Intel i386 implementation
 *  of RTEMS.
 *
 *  COPYRIGHT (c) 1989-1999.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.org/license/LICENSE.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <rtems/asm.h>
#include <rtems/score/cpu.h>

#ifndef CPU_STACK_ALIGNMENT
#error "Missing header? CPU_STACK_ALIGNMENT not defined"
#endif

/*
 * Format of i386 Register structure
 */

.set REG_EFLAGS,  I386_CONTEXT_CONTROL_EFLAGS_OFFSET
.set REG_ESP,     I386_CONTEXT_CONTROL_ESP_OFFSET
.set REG_EBP,     I386_CONTEXT_CONTROL_EBP_OFFSET
.set REG_EBX,     I386_CONTEXT_CONTROL_EBX_OFFSET
.set REG_ESI,     I386_CONTEXT_CONTROL_ESI_OFFSET
.set REG_EDI,     I386_CONTEXT_CONTROL_EDI_OFFSET

        BEGIN_CODE

/*
 *  void _CPU_Context_switch( run_context, heir_context )
 *
 *  This routine performs a normal non-FP context.
 */

        .p2align  1
        PUBLIC (_CPU_Context_switch)

.set RUNCONTEXT_ARG,   4                   /* save context argument */
.set HEIRCONTEXT_ARG,  8                   /* restore context argument */

SYM (_CPU_Context_switch):
        movl      RUNCONTEXT_ARG(esp),eax  /* eax = running threads context */
        pushf                              /* push eflags */
        popl      REG_EFLAGS(eax)          /* save eflags */
        movl      esp,REG_ESP(eax)         /* save stack pointer */
        movl      ebp,REG_EBP(eax)         /* save base pointer */
        movl      ebx,REG_EBX(eax)         /* save ebx */
        movl      esi,REG_ESI(eax)         /* save source register */
        movl      edi,REG_EDI(eax)         /* save destination register */

#ifdef RTEMS_SMP
        /* Indicate that this context is no longer executing */
        movb      $0, I386_CONTEXT_CONTROL_IS_EXECUTING_OFFSET(eax)
#endif

        movl      HEIRCONTEXT_ARG(esp),eax /* eax = heir threads context */

restore:
#ifdef RTEMS_SMP
        /* Wait for context to stop execution if necessary */
1:
        movb      I386_CONTEXT_CONTROL_IS_EXECUTING_OFFSET(eax), bl
        testb     bl, bl
        jne       1b

        /* Indicate that this context is executing */
        movb      $1, I386_CONTEXT_CONTROL_IS_EXECUTING_OFFSET(eax)
#endif

        pushl     REG_EFLAGS(eax)          /* push eflags */
        popf                               /* restore eflags */
        movl      REG_ESP(eax),esp         /* restore stack pointer */
        movl      REG_EBP(eax),ebp         /* restore base pointer */
        movl      REG_EBX(eax),ebx         /* restore ebx */
        movl      REG_ESI(eax),esi         /* restore source register */
        movl      REG_EDI(eax),edi         /* restore destination register */
        ret

/*
 *  NOTE: May be unnecessary to reload some registers.
 */

/*
 *  void _CPU_Context_restore( new_context )
 *
 *  This routine performs a normal non-FP context.
 */

        PUBLIC (_CPU_Context_restore)

.set NEWCONTEXT_ARG,   4                   /* context to restore argument */

SYM (_CPU_Context_restore):
        movl      NEWCONTEXT_ARG(esp),eax  /* eax = running threads context */
        jmp       restore

/*void _CPU_Context_save_fp_context( &fp_context_ptr )
 *  void _CPU_Context_restore_fp_context( &fp_context_ptr )
 *
 *  This section is used to context switch an i80287, i80387,
 *  the built-in coprocessor or the i80486 or compatible.
 */

.set FPCONTEXT_ARG,   4                    /* FP context argument */

#ifndef __SSE__
        .p2align  1
        PUBLIC (_CPU_Context_save_fp)
SYM (_CPU_Context_save_fp):
        movl      FPCONTEXT_ARG(esp),eax   /* eax = &ptr to FP context area */
        movl      (eax),eax                /* eax = FP context area */
        fsave     (eax)                    /* save FP context */
        ret

        .p2align  1
        PUBLIC (_CPU_Context_restore_fp)
SYM (_CPU_Context_restore_fp):
        movl      FPCONTEXT_ARG(esp),eax   /* eax = &ptr to FP context area */
        movl      (eax),eax                /* eax = FP context area */
        frstor    (eax)                    /* restore FP context */
        ret
#endif

#ifdef __SSE__
#define SSE_OFF  16
#endif

        PUBLIC (_Exception_Handler)
SYM (_Exception_Handler):
        pusha                  /* Push general purpose registers    */
        pushl   $0             /* Null pointer to SSE area          */
        movl    esp,  ebp      /* Save original SP                  */
#ifndef __SSE__
        subl    $4,   esp      /* Reserve space for argument        */
                           /* Align stack (courtesy for C/gcc)  */
        andl    $ - CPU_STACK_ALIGNMENT, esp
#else
        subl    $512, esp      /* Space for SSE area                */
                           /* Align stack (courtesy for C/gcc)  */
        andl    $ - CPU_STACK_ALIGNMENT, esp
/* Doing fwait here will re-throw an already pending FP exception!
        fwait
 */
        fxsave  0(esp)
        fninit                 /* Clean-slate FPU                   */
        movl    $0x1f80, 0(ebp)
        ldmxcsr 0(ebp)         /* Clean-slate MXCSR                 */
        movl    esp, 0(ebp)    /* Store pointer to SSE area         */
        subl    $SSE_OFF, esp  /* Aligned space for argument        */
#endif
        movl    ebp, (esp)     /* Store argument                    */
        movl    _currentExcHandler, eax    /* Call function stored in _currentExcHandler */
        call    * eax
#ifdef __SSE__
        fwait
        fxrstor 16(esp)
#endif
        movl    ebp,  esp      /* Restore original SP               */
        addl    $4,   esp      /* Skill pointer to SSE area         */
        popa                   /* Restore general purpose registers */
        addl    $8, esp        /* Skill vector number and faultCode */
        iret

#define DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY(_vector) \
        .p2align 4                         ; \
        PUBLIC (rtems_exception_prologue_ ## _vector ) ; \
SYM (rtems_exception_prologue_ ## _vector ):             \
        pushl   $ _vector       ; \
        jmp   SYM (_Exception_Handler) ;

#define DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY(_vector) \
        .p2align 4                         ; \
        PUBLIC (rtems_exception_prologue_ ## _vector ) ; \
SYM (rtems_exception_prologue_ ## _vector ):             \
        pushl   $ 0             ; \
        pushl   $ _vector       ; \
        jmp   SYM (_Exception_Handler) ;

/*
 * Divide Error
 */
DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (0)
/*
 * Debug Exception
 */
DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (1)
/*
 * NMI
 */
DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (2)
/*
 * Breakpoint
 */
DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (3)
/*
 * Overflow
 */
DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (4)
/*
 * Bound Range Exceeded
 */
DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (5)
/*
 * Invalid Opcode
 */
DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (6)
/*
 * No Math Coproc
 */
DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (7)
/*
 * Double Fault
 */
DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (8)
/*
 * Coprocessor segment overrun
 */
DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (9)
/*
 * Invalid TSS
 */
DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (10)
/*
 * Segment Not Present
 */
DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (11)
/*
 * Stack segment Fault
 */
DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (12)
/*
 * General Protection Fault
 */
DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (13)
/*
 * Page Fault
 */
DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (14)
/*
 * Floating point error (NB 15 is reserved it is therefor skipped)
 */
DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (16)
/*
 * Aligment Check
 */
DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (17)
/*
 * Machine Check
 */
DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (18)

#ifdef __SSE__
/*
 * SIMD FP Exception
 */
DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (19)
#endif


/*
 *  void *i386_Logical_to_physical(
 *     uint16_t    segment,
 *     void             *address
 *  );
 *
 *  Returns thirty-two bit physical address for segment:address.
 */

.set SEGMENT_ARG, 4
.set ADDRESS_ARG, 8

             PUBLIC (i386_Logical_to_physical)

SYM (i386_Logical_to_physical):

        xorl    eax,eax                /* clear eax */
        movzwl  SEGMENT_ARG(esp),ecx   /* ecx = segment value */
        movl    $ SYM (_Global_descriptor_table),edx
                                       /* edx = address of our GDT */
        addl    ecx,edx                /* edx = address of desired entry */
        movb    7(edx),ah              /* ah = base 31:24 */
        movb    4(edx),al              /* al = base 23:16 */
        shll    $16,eax                /* move ax into correct bits */
        movw    2(edx),ax              /* ax = base 0:15 */
        movl    ADDRESS_ARG(esp),ecx   /* ecx = address to convert */
        addl    eax,ecx                /* ecx = physical address equivalent */
        movl    ecx,eax                /* eax = ecx */
        ret

/*
 *  void *i386_Physical_to_logical(
 *     uint16_t    segment,
 *     void             *address
 *  );
 *
 *  Returns thirty-two bit physical address for segment:address.
 */

/*
 *.set SEGMENT_ARG, 4
 *.set ADDRESS_ARG, 8   -- use sets from above
 */

       PUBLIC (i386_Physical_to_logical)

SYM (i386_Physical_to_logical):
        xorl    eax,eax                /* clear eax */
        movzwl  SEGMENT_ARG(esp),ecx   /* ecx = segment value */
        movl    $ SYM (_Global_descriptor_table),edx
                                       /* edx = address of our GDT */
        addl    ecx,edx                /* edx = address of desired entry */
        movb    7(edx),ah              /* ah = base 31:24 */
        movb    4(edx),al              /* al = base 23:16 */
        shll    $16,eax                /* move ax into correct bits */
        movw    2(edx),ax              /* ax = base 0:15 */
        movl    ADDRESS_ARG(esp),ecx   /* ecx = address to convert */
        subl    eax,ecx                /* ecx = logical address equivalent */
        movl    ecx,eax                /* eax = ecx */
        ret

END_CODE

END