Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/* $Id: rtrap.S,v 1.58 2002/01/31 03:30:05 davem Exp $
 * rtrap.S: Return from Sparc trap low-level code.
 *
 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
 */

#include <asm/page.h>
#include <asm/ptrace.h>
#include <asm/psr.h>
#include <asm/asi.h>
#include <asm/smp.h>
#include <asm/contregs.h>
#include <asm/winmacro.h>
#include <asm/asmmacro.h>
#include <asm/thread_info.h>

#define t_psr     l0
#define t_pc      l1
#define t_npc     l2
#define t_wim     l3
#define twin_tmp1 l4
#define glob_tmp  g4
#define curptr    g6

        /* 7 WINDOW SPARC PATCH INSTRUCTIONS */
        .globl  rtrap_7win_patch1, rtrap_7win_patch2, rtrap_7win_patch3
        .globl  rtrap_7win_patch4, rtrap_7win_patch5
rtrap_7win_patch1:      srl     %t_wim, 0x6, %glob_tmp
rtrap_7win_patch2:      and     %glob_tmp, 0x7f, %glob_tmp
rtrap_7win_patch3:      srl     %g1, 7, %g2
rtrap_7win_patch4:      srl     %g2, 6, %g2
rtrap_7win_patch5:      and     %g1, 0x7f, %g1
        /* END OF PATCH INSTRUCTIONS */

        /* We need to check for a few things which are:
         * 1) The need to call schedule() because this
         *    processes quantum is up.
         * 2) Pending signals for this process, if any
         *    exist we need to call do_signal() to do
         *    the needy.
         *
         * Else we just check if the rett would land us
         * in an invalid window, if so we need to grab
         * it off the user/kernel stack first.
         */

        .globl  ret_trap_entry, rtrap_patch1, rtrap_patch2
        .globl  rtrap_patch3, rtrap_patch4, rtrap_patch5
        .globl  ret_trap_lockless_ipi
ret_trap_entry:
ret_trap_lockless_ipi:
        andcc   %t_psr, PSR_PS, %g0
        be      1f
         nop

        wr      %t_psr, 0x0, %psr
        b       ret_trap_kernel
         nop

1:
        ld      [%curptr + TI_FLAGS], %g2
        andcc   %g2, (_TIF_NEED_RESCHED), %g0
        be      signal_p
         nop

        call    schedule
         nop

        ld      [%curptr + TI_FLAGS], %g2
signal_p:
        andcc   %g2, (_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK), %g0
        bz,a    ret_trap_continue
         ld     [%sp + STACKFRAME_SZ + PT_PSR], %t_psr

        mov     %l5, %o1
        mov     %l6, %o2
        call    do_signal
         add    %sp, STACKFRAME_SZ, %o0 ! pt_regs ptr

        /* Fall through. */
        ld      [%sp + STACKFRAME_SZ + PT_PSR], %t_psr
        clr     %l6
ret_trap_continue:
        wr      %t_psr, 0x0, %psr
        WRITE_PAUSE

        ld      [%curptr + TI_W_SAVED], %twin_tmp1
        orcc    %g0, %twin_tmp1, %g0
        be      ret_trap_nobufwins
         nop

        wr      %t_psr, PSR_ET, %psr
        WRITE_PAUSE

        mov     1, %o1
        call    try_to_clear_window_buffer
         add    %sp, STACKFRAME_SZ, %o0

        b       signal_p
         ld     [%curptr + TI_FLAGS], %g2

ret_trap_nobufwins:
        /* Load up the user's out registers so we can pull
         * a window from the stack, if necessary.
         */
        LOAD_PT_INS(sp)

        /* If there are already live user windows in the
         * set we can return from trap safely.
         */
        ld      [%curptr + TI_UWINMASK], %twin_tmp1
        orcc    %g0, %twin_tmp1, %g0
        bne     ret_trap_userwins_ok
         nop

                /* Calculate new %wim, we have to pull a register
                 * window from the users stack.
                 */
ret_trap_pull_one_window:
                rd      %wim, %t_wim
                sll     %t_wim, 0x1, %twin_tmp1
rtrap_patch1:   srl     %t_wim, 0x7, %glob_tmp
                or      %glob_tmp, %twin_tmp1, %glob_tmp
rtrap_patch2:   and     %glob_tmp, 0xff, %glob_tmp

                wr      %glob_tmp, 0x0, %wim

                                /* Here comes the architecture specific 
                                 * branch to the user stack checking routine
                                 * for return from traps.
                                 */
                                .globl  rtrap_mmu_patchme
rtrap_mmu_patchme:      b       sun4c_rett_stackchk
                                 andcc  %fp, 0x7, %g0   

ret_trap_userwins_ok:
        LOAD_PT_PRIV(sp, t_psr, t_pc, t_npc)
        or      %t_pc, %t_npc, %g2
        andcc   %g2, 0x3, %g0
        be      1f
         nop

        b       ret_trap_unaligned_pc
         add    %sp, STACKFRAME_SZ, %o0

1:
        LOAD_PT_YREG(sp, g1)
        LOAD_PT_GLOBALS(sp)

        wr      %t_psr, 0x0, %psr
        WRITE_PAUSE

        jmp     %t_pc
        rett    %t_npc
        
ret_trap_unaligned_pc:
        ld      [%sp + STACKFRAME_SZ + PT_PC], %o1
        ld      [%sp + STACKFRAME_SZ + PT_NPC], %o2
        ld      [%sp + STACKFRAME_SZ + PT_PSR], %o3

        wr      %t_wim, 0x0, %wim               ! or else...

        wr      %t_psr, PSR_ET, %psr
        WRITE_PAUSE

        call    do_memaccess_unaligned
         nop

        b       signal_p
         ld     [%curptr + TI_FLAGS], %g2

ret_trap_kernel:
                /* Will the rett land us in the invalid window? */
                mov     2, %g1
                sll     %g1, %t_psr, %g1
rtrap_patch3:   srl     %g1, 8, %g2
                or      %g1, %g2, %g1
                rd      %wim, %g2
                andcc   %g2, %g1, %g0
                be      1f              ! Nope, just return from the trap
                 sll    %g2, 0x1, %g1

                /* We have to grab a window before returning. */
rtrap_patch4:   srl     %g2, 7,  %g2
                or      %g1, %g2, %g1
rtrap_patch5:   and     %g1, 0xff, %g1

        wr      %g1, 0x0, %wim

        /* Grrr, make sure we load from the right %sp... */
        LOAD_PT_ALL(sp, t_psr, t_pc, t_npc, g1)

        restore %g0, %g0, %g0
        LOAD_WINDOW(sp)
        b       2f
         save   %g0, %g0, %g0

        /* Reload the entire frame in case this is from a
         * kernel system call or whatever...
         */
1:
        LOAD_PT_ALL(sp, t_psr, t_pc, t_npc, g1)
2:
        wr      %t_psr, 0x0, %psr
        WRITE_PAUSE

        jmp     %t_pc
        rett    %t_npc

ret_trap_user_stack_is_bolixed:
        wr      %t_wim, 0x0, %wim

        wr      %t_psr, PSR_ET, %psr
        WRITE_PAUSE

        call    window_ret_fault
         add    %sp, STACKFRAME_SZ, %o0

        b       signal_p
         ld     [%curptr + TI_FLAGS], %g2


        .globl  sun4c_rett_stackchk
sun4c_rett_stackchk:
        be      1f
         and    %fp, 0xfff, %g1         ! delay slot

        b       ret_trap_user_stack_is_bolixed + 0x4
         wr     %t_wim, 0x0, %wim

        /* See if we have to check the sanity of one page or two */
1:
        add     %g1, 0x38, %g1
        sra     %fp, 29, %g2
        add     %g2, 0x1, %g2
        andncc  %g2, 0x1, %g0
        be      1f
         andncc %g1, 0xff8, %g0

        /* %sp is in vma hole, yuck */
        b       ret_trap_user_stack_is_bolixed + 0x4
         wr     %t_wim, 0x0, %wim

1:
        be      sun4c_rett_onepage      /* Only one page to check */
         lda    [%fp] ASI_PTE, %g2

sun4c_rett_twopages:
        add     %fp, 0x38, %g1
        sra     %g1, 29, %g2
        add     %g2, 0x1, %g2
        andncc  %g2, 0x1, %g0
        be      1f
         lda    [%g1] ASI_PTE, %g2

        /* Second page is in vma hole */
        b       ret_trap_user_stack_is_bolixed + 0x4
         wr     %t_wim, 0x0, %wim

1:
        srl     %g2, 29, %g2
        andcc   %g2, 0x4, %g0
        bne     sun4c_rett_onepage
         lda    [%fp] ASI_PTE, %g2

        /* Second page has bad perms */
        b       ret_trap_user_stack_is_bolixed + 0x4
         wr     %t_wim, 0x0, %wim

sun4c_rett_onepage:
        srl     %g2, 29, %g2
        andcc   %g2, 0x4, %g0
        bne,a   1f
         restore %g0, %g0, %g0

        /* A page had bad page permissions, losing... */
        b       ret_trap_user_stack_is_bolixed + 0x4
         wr     %t_wim, 0x0, %wim

        /* Whee, things are ok, load the window and continue. */
1:
        LOAD_WINDOW(sp)

        b       ret_trap_userwins_ok
         save   %g0, %g0, %g0

        .globl  srmmu_rett_stackchk
srmmu_rett_stackchk:
        bne     ret_trap_user_stack_is_bolixed
         sethi   %hi(PAGE_OFFSET), %g1
        cmp     %g1, %fp
        bleu    ret_trap_user_stack_is_bolixed
         mov    AC_M_SFSR, %g1
        lda     [%g1] ASI_M_MMUREGS, %g0

        lda     [%g0] ASI_M_MMUREGS, %g1
        or      %g1, 0x2, %g1
        sta     %g1, [%g0] ASI_M_MMUREGS

        restore %g0, %g0, %g0

        LOAD_WINDOW(sp)

        save    %g0, %g0, %g0

        andn    %g1, 0x2, %g1
        sta     %g1, [%g0] ASI_M_MMUREGS

        mov     AC_M_SFAR, %g2
        lda     [%g2] ASI_M_MMUREGS, %g2

        mov     AC_M_SFSR, %g1
        lda     [%g1] ASI_M_MMUREGS, %g1
        andcc   %g1, 0x2, %g0
        be      ret_trap_userwins_ok
         nop

        b,a     ret_trap_user_stack_is_bolixed