entry.h

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#ifndef __M68K_ENTRY_H
#define __M68K_ENTRY_H

#include <asm/setup.h>
#include <asm/page.h>
#ifdef __ASSEMBLY__
#include <asm/thread_info.h>
#endif

/*
 * Stack layout in 'ret_from_exception':
 *
 *  This allows access to the syscall arguments in registers d1-d5
 *
 *   0(sp) - d1
 *   4(sp) - d2
 *   8(sp) - d3
 *   C(sp) - d4
 *  10(sp) - d5
 *  14(sp) - a0
 *  18(sp) - a1
 *  1C(sp) - a2
 *  20(sp) - d0
 *  24(sp) - orig_d0
 *  28(sp) - stack adjustment
 *  2C(sp) - [ sr              ] [ format & vector ]
 *  2E(sp) - [ pc-hiword       ] [ sr              ]
 *  30(sp) - [ pc-loword       ] [ pc-hiword       ]
 *  32(sp) - [ format & vector ] [ pc-loword       ]
 *        ^^^^^^^^^^^^^^^^^   ^^^^^^^^^^^^^^^^^
 *          M68K          COLDFIRE
 */

/* the following macro is used when enabling interrupts */
#if defined(MACH_ATARI_ONLY)
    /* block out HSYNC = ipl 2 on the atari */
#define ALLOWINT    (~0x500)
#else
    /* portable version */
#define ALLOWINT    (~0x700)
#endif /* machine compilation types */

#ifdef __ASSEMBLY__
/*
 * This defines the normal kernel pt-regs layout.
 *
 * regs a3-a6 and d6-d7 are preserved by C code
 * the kernel doesn't mess with usp unless it needs to
 */
#define SWITCH_STACK_SIZE   (6*4+4) /* includes return address */

#ifdef CONFIG_COLDFIRE
#ifdef CONFIG_COLDFIRE_SW_A7
/*
 * This is made a little more tricky on older ColdFires. There is no
 * separate supervisor and user stack pointers. Need to artificially
 * construct a usp in software... When doing this we need to disable
 * interrupts, otherwise bad things will happen.
 */
.globl sw_usp
.globl sw_ksp

.macro SAVE_ALL_SYS
    move    #0x2700,%sr     /* disable intrs */
    btst    #5,%sp@(2)      /* from user? */
    bnes    6f          /* no, skip */
    movel   %sp,sw_usp      /* save user sp */
    addql   #8,sw_usp       /* remove exception */
    movel   sw_ksp,%sp      /* kernel sp */
    subql   #8,%sp          /* room for exception */
    clrl    %sp@-           /* stkadj */
    movel   %d0,%sp@-       /* orig d0 */
    movel   %d0,%sp@-       /* d0 */
    lea %sp@(-32),%sp       /* space for 8 regs */
    moveml  %d1-%d5/%a0-%a2,%sp@
    movel   sw_usp,%a0      /* get usp */
    movel   %a0@-,%sp@(PT_OFF_PC)   /* copy exception program counter */
    movel   %a0@-,%sp@(PT_OFF_FORMATVEC)/*copy exception format/vector/sr */
    bra 7f
    6:
    clrl    %sp@-           /* stkadj */
    movel   %d0,%sp@-       /* orig d0 */
    movel   %d0,%sp@-       /* d0 */
    lea %sp@(-32),%sp       /* space for 8 regs */
    moveml  %d1-%d5/%a0-%a2,%sp@
    7:
.endm

.macro SAVE_ALL_INT
    SAVE_ALL_SYS
    moveq   #-1,%d0         /* not system call entry */
    movel   %d0,%sp@(PT_OFF_ORIG_D0)
.endm

.macro RESTORE_USER
    move    #0x2700,%sr     /* disable intrs */
    movel   sw_usp,%a0      /* get usp */
    movel   %sp@(PT_OFF_PC),%a0@-   /* copy exception program counter */
    movel   %sp@(PT_OFF_FORMATVEC),%a0@-/*copy exception format/vector/sr */
    moveml  %sp@,%d1-%d5/%a0-%a2
    lea %sp@(32),%sp        /* space for 8 regs */
    movel   %sp@+,%d0
    addql   #4,%sp          /* orig d0 */
    addl    %sp@+,%sp       /* stkadj */
    addql   #8,%sp          /* remove exception */
    movel   %sp,sw_ksp      /* save ksp */
    subql   #8,sw_usp       /* set exception */
    movel   sw_usp,%sp      /* restore usp */
    rte
.endm

.macro RDUSP
    movel   sw_usp,%a3
.endm

.macro WRUSP
    movel   %a3,sw_usp
.endm

#else /* !CONFIG_COLDFIRE_SW_A7 */
/*
 * Modern ColdFire parts have separate supervisor and user stack
 * pointers. Simple load and restore macros for this case.
 */
.macro SAVE_ALL_SYS
    move    #0x2700,%sr     /* disable intrs */
    clrl    %sp@-           /* stkadj */
    movel   %d0,%sp@-       /* orig d0 */
    movel   %d0,%sp@-       /* d0 */
    lea %sp@(-32),%sp       /* space for 8 regs */
    moveml  %d1-%d5/%a0-%a2,%sp@
.endm

.macro SAVE_ALL_INT
    move    #0x2700,%sr     /* disable intrs */
    clrl    %sp@-           /* stkadj */
    pea -1:w            /* orig d0 */
    movel   %d0,%sp@-       /* d0 */
    lea %sp@(-32),%sp       /* space for 8 regs */
    moveml  %d1-%d5/%a0-%a2,%sp@
.endm

.macro RESTORE_USER
    moveml  %sp@,%d1-%d5/%a0-%a2
    lea %sp@(32),%sp        /* space for 8 regs */
    movel   %sp@+,%d0
    addql   #4,%sp          /* orig d0 */
    addl    %sp@+,%sp       /* stkadj */
    rte
.endm

.macro RDUSP
    /*move  %usp,%a3*/
    .word   0x4e6b
.endm

.macro WRUSP
    /*move  %a3,%usp*/
    .word   0x4e63
.endm

#endif /* !CONFIG_COLDFIRE_SW_A7 */

.macro SAVE_SWITCH_STACK
    lea %sp@(-24),%sp       /* 6 regs */
    moveml  %a3-%a6/%d6-%d7,%sp@
.endm

.macro RESTORE_SWITCH_STACK
    moveml  %sp@,%a3-%a6/%d6-%d7
    lea %sp@(24),%sp        /* 6 regs */
.endm

#else /* !CONFIG_COLDFIRE */

/*
 * All other types of m68k parts (68000, 680x0, CPU32) have the same
 * entry and exit code.
 */

/*
 * a -1 in the orig_d0 field signifies
 * that the stack frame is NOT for syscall
 */
.macro SAVE_ALL_INT
    clrl    %sp@-           /* stk_adj */
    pea -1:w            /* orig d0 */
    movel   %d0,%sp@-       /* d0 */
    moveml  %d1-%d5/%a0-%a2,%sp@-
.endm

.macro SAVE_ALL_SYS
    clrl    %sp@-           /* stk_adj */
    movel   %d0,%sp@-       /* orig d0 */
    movel   %d0,%sp@-       /* d0 */
    moveml  %d1-%d5/%a0-%a2,%sp@-
.endm

.macro RESTORE_ALL
    moveml  %sp@+,%a0-%a2/%d1-%d5
    movel   %sp@+,%d0
    addql   #4,%sp          /* orig d0 */
    addl    %sp@+,%sp       /* stk adj */
    rte
.endm


.macro SAVE_SWITCH_STACK
    moveml  %a3-%a6/%d6-%d7,%sp@-
.endm

.macro RESTORE_SWITCH_STACK
    moveml  %sp@+,%a3-%a6/%d6-%d7
.endm

#endif /* !CONFIG_COLDFIRE */

/*
 * Register %a2 is reserved and set to current task on MMU enabled systems.
 * Non-MMU systems do not reserve %a2 in this way, and this definition is
 * not used for them.
 */
#ifdef CONFIG_MMU

#define curptr a2

#define GET_CURRENT(tmp) get_current tmp
.macro get_current reg=%d0
    movel   %sp,\reg
    andl    #-THREAD_SIZE,\reg
    movel	\reg,%curptr
    movel   %curptr@,%curptr
.endm

#else

#define GET_CURRENT(tmp)

#endif /* CONFIG_MMU */

#else /* C source */

#define STR(X) STR1(X)
#define STR1(X) #X

#define SAVE_ALL_INT                \
    "clrl   %%sp@-;"    /* stk_adj */   \
    "pea    -1:w;"      /* orig d0 = -1 */  \
    "movel  %%d0,%%sp@-;" /* d0 */      \
    "moveml %%d1-%%d5/%%a0-%%a2,%%sp@-"

#define GET_CURRENT(tmp) \
    "movel  %%sp,"#tmp"\n\t" \
    "andw   #-"STR(THREAD_SIZE)","#tmp"\n\t" \
    "movel  "#tmp",%%a2\n\t" \
    "movel  %%a2@,%%a2"

#endif

#endif /* __M68K_ENTRY_H */