LXR linux/arch/sparc/kernel/etrap.S

   1/* $Id: etrap.S,v 1.31 2000/01/08 16:38:18 anton Exp $
   2 * etrap.S: Sparc trap window preparation for entry into the
   3 *          Linux kernel.
   4 *
   5 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   6 */
   7
   8#include <asm/head.h>
   9#include <asm/asi.h>
  10#include <asm/contregs.h>
  11#include <asm/page.h>
  12#include <asm/psr.h>
  13#include <asm/ptrace.h>
  14#include <asm/winmacro.h>
  15#include <asm/asmmacro.h>
  16#include <asm/thread_info.h>
  17
  18/* Registers to not touch at all. */
  19#define t_psr        l0 /* Set by caller */
  20#define t_pc         l1 /* Set by caller */
  21#define t_npc        l2 /* Set by caller */
  22#define t_wim        l3 /* Set by caller */
  23#define t_twinmask   l4 /* Set at beginning of this entry routine. */
  24#define t_kstack     l5 /* Set right before pt_regs frame is built */
  25#define t_retpc      l6 /* If you change this, change winmacro.h header file */
  26#define t_systable   l7 /* Never touch this, could be the syscall table ptr. */
  27#define curptr       g6 /* Set after pt_regs frame is built */
  28
  29        .text
  30        .align 4
  31
  32        /* SEVEN WINDOW PATCH INSTRUCTIONS */
  33        .globl  tsetup_7win_patch1, tsetup_7win_patch2
  34        .globl  tsetup_7win_patch3, tsetup_7win_patch4
  35        .globl  tsetup_7win_patch5, tsetup_7win_patch6
  36tsetup_7win_patch1:     sll     %t_wim, 0x6, %t_wim
  37tsetup_7win_patch2:     and     %g2, 0x7f, %g2
  38tsetup_7win_patch3:     and     %g2, 0x7f, %g2
  39tsetup_7win_patch4:     and     %g1, 0x7f, %g1
  40tsetup_7win_patch5:     sll     %t_wim, 0x6, %t_wim
  41tsetup_7win_patch6:     and     %g2, 0x7f, %g2
  42        /* END OF PATCH INSTRUCTIONS */
  43
  44        /* At trap time, interrupts and all generic traps do the
  45         * following:
  46         *
  47         * rd   %psr, %l0
  48         * b    some_handler
  49         * rd   %wim, %l3
  50         * nop
  51         *
  52         * Then 'some_handler' if it needs a trap frame (ie. it has
  53         * to call c-code and the trap cannot be handled in-window)
  54         * then it does the SAVE_ALL macro in entry.S which does
  55         *
  56         * sethi        %hi(trap_setup), %l4
  57         * jmpl         %l4 + %lo(trap_setup), %l6
  58         * nop
  59         */
  60
  61        /* 2 3 4  window number
  62         * -----
  63         * O T S  mnemonic
  64         *
  65         * O == Current window before trap
  66         * T == Window entered when trap occurred
  67         * S == Window we will need to save if (1<<T) == %wim
  68         *
  69         * Before execution gets here, it must be guaranteed that
  70         * %l0 contains trap time %psr, %l1 and %l2 contain the
  71         * trap pc and npc, and %l3 contains the trap time %wim.
  72         */
  73
  74        .globl  trap_setup, tsetup_patch1, tsetup_patch2
  75        .globl  tsetup_patch3, tsetup_patch4
  76        .globl  tsetup_patch5, tsetup_patch6
  77trap_setup:
  78        /* Calculate mask of trap window.  See if from user
  79         * or kernel and branch conditionally.
  80         */
  81        mov     1, %t_twinmask
  82        andcc   %t_psr, PSR_PS, %g0              ! fromsupv_p = (psr & PSR_PS)
  83        be      trap_setup_from_user             ! nope, from user mode
  84         sll    %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr)
  85
  86        /* From kernel, allocate more kernel stack and
  87         * build a pt_regs trap frame.
  88         */
  89        sub     %fp, (STACKFRAME_SZ + TRACEREG_SZ), %t_kstack
  90        STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2)
  91
  92        /* See if we are in the trap window. */
  93        andcc   %t_twinmask, %t_wim, %g0
  94        bne     trap_setup_kernel_spill         ! in trap window, clean up
  95         nop
  96
  97        /* Trap from kernel with a window available.
  98         * Just do it...
  99         */
 100        jmpl    %t_retpc + 0x8, %g0     ! return to caller
 101         mov    %t_kstack, %sp          ! jump onto new stack
 102
 103trap_setup_kernel_spill:
 104        ld      [%curptr + TI_UWINMASK], %g1
 105        orcc    %g0, %g1, %g0
 106        bne     trap_setup_user_spill   ! there are some user windows, yuck
 107        /* Spill from kernel, but only kernel windows, adjust
 108         * %wim and go.
 109         */
 110         srl    %t_wim, 0x1, %g2        ! begin computation of new %wim
 111tsetup_patch1:
 112        sll     %t_wim, 0x7, %t_wim     ! patched on 7 window Sparcs
 113        or      %t_wim, %g2, %g2
 114tsetup_patch2:
 115        and     %g2, 0xff, %g2          ! patched on 7 window Sparcs
 116
 117        save    %g0, %g0, %g0
 118
 119        /* Set new %wim value */
 120        wr      %g2, 0x0, %wim
 121
 122        /* Save the kernel window onto the corresponding stack. */
 123        STORE_WINDOW(sp)
 124
 125        restore %g0, %g0, %g0
 126
 127        jmpl    %t_retpc + 0x8, %g0     ! return to caller
 128         mov    %t_kstack, %sp          ! and onto new kernel stack
 129
 130#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ)
 131
 132trap_setup_from_user:
 133        /* We can't use %curptr yet. */
 134        LOAD_CURRENT(t_kstack, t_twinmask)
 135
 136        sethi   %hi(STACK_OFFSET), %t_twinmask
 137        or      %t_twinmask, %lo(STACK_OFFSET), %t_twinmask
 138        add     %t_kstack, %t_twinmask, %t_kstack
 139
 140        mov     1, %t_twinmask
 141        sll     %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr)
 142
 143        /* Build pt_regs frame. */
 144        STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2)
 145
 146#if 0
 147        /* If we're sure every task_struct is THREAD_SIZE aligned,
 148           we can speed this up. */
 149        sethi   %hi(STACK_OFFSET), %curptr
 150        or      %curptr, %lo(STACK_OFFSET), %curptr
 151        sub     %t_kstack, %curptr, %curptr
 152#else
 153        sethi   %hi(~(THREAD_SIZE - 1)), %curptr
 154        and     %t_kstack, %curptr, %curptr
 155#endif
 156
 157        /* Clear current_thread_info->w_saved */
 158        st      %g0, [%curptr + TI_W_SAVED]
 159
 160        /* See if we are in the trap window. */
 161        andcc   %t_twinmask, %t_wim, %g0
 162        bne     trap_setup_user_spill           ! yep we are
 163         orn    %g0, %t_twinmask, %g1           ! negate trap win mask into %g1
 164
 165        /* Trap from user, but not into the invalid window.
 166         * Calculate new umask.  The way this works is,
 167         * any window from the %wim at trap time until
 168         * the window right before the one we are in now,
 169         * is a user window.  A diagram:
 170         *
 171         *      7 6 5 4 3 2 1 0    window number
 172         *      ---------------
 173         *        I     L T        mnemonic
 174         *
 175         * Window 'I' is the invalid window in our example,
 176         * window 'L' is the window the user was in when
 177         * the trap occurred, window T is the trap window
 178         * we are in now.  So therefore, windows 5, 4 and
 179         * 3 are user windows.  The following sequence
 180         * computes the user winmask to represent this.
 181         */
 182        subcc   %t_wim, %t_twinmask, %g2
 183        bneg,a  1f
 184         sub    %g2, 0x1, %g2
 1851:
 186        andn    %g2, %t_twinmask, %g2
 187tsetup_patch3:
 188        and     %g2, 0xff, %g2                  ! patched on 7win Sparcs
 189        st      %g2, [%curptr + TI_UWINMASK]    ! store new umask
 190
 191        jmpl    %t_retpc + 0x8, %g0             ! return to caller
 192         mov    %t_kstack, %sp                  ! and onto kernel stack
 193
 194trap_setup_user_spill:
 195        /* A spill occurred from either kernel or user mode
 196         * and there exist some user windows to deal with.
 197         * A mask of the currently valid user windows
 198         * is in %g1 upon entry to here.
 199         */
 200
 201tsetup_patch4:
 202        and     %g1, 0xff, %g1          ! patched on 7win Sparcs, mask
 203        srl     %t_wim, 0x1, %g2        ! compute new %wim
 204tsetup_patch5:
 205        sll     %t_wim, 0x7, %t_wim     ! patched on 7win Sparcs
 206        or      %t_wim, %g2, %g2        ! %g2 is new %wim
 207tsetup_patch6:
 208        and     %g2, 0xff, %g2          ! patched on 7win Sparcs
 209        andn    %g1, %g2, %g1           ! clear this bit in %g1
 210        st      %g1, [%curptr + TI_UWINMASK]
 211
 212        save    %g0, %g0, %g0
 213
 214        wr      %g2, 0x0, %wim
 215
 216        /* Call MMU-architecture dependent stack checking
 217         * routine.
 218         */
 219        .globl  tsetup_mmu_patchme
 220tsetup_mmu_patchme:
 221        b       tsetup_sun4c_stackchk
 222         andcc  %sp, 0x7, %g0
 223
 224        /* Architecture specific stack checking routines.  When either
 225         * of these routines are called, the globals are free to use
 226         * as they have been safely stashed on the new kernel stack
 227         * pointer.  Thus the definition below for simplicity.
 228         */
 229#define glob_tmp     g1
 230
 231        .globl  tsetup_sun4c_stackchk
 232tsetup_sun4c_stackchk:
 233        /* Done by caller: andcc %sp, 0x7, %g0 */
 234        bne     trap_setup_user_stack_is_bolixed
 235         sra    %sp, 29, %glob_tmp
 236
 237        add     %glob_tmp, 0x1, %glob_tmp
 238        andncc  %glob_tmp, 0x1, %g0
 239        bne     trap_setup_user_stack_is_bolixed
 240         and    %sp, 0xfff, %glob_tmp           ! delay slot
 241
 242        /* See if our dump area will be on more than one
 243         * page.
 244         */
 245        add     %glob_tmp, 0x38, %glob_tmp
 246        andncc  %glob_tmp, 0xff8, %g0
 247        be      tsetup_sun4c_onepage            ! only one page to check
 248         lda    [%sp] ASI_PTE, %glob_tmp        ! have to check first page anyways
 249
 250tsetup_sun4c_twopages:
 251        /* Is first page ok permission wise? */
 252        srl     %glob_tmp, 29, %glob_tmp
 253        cmp     %glob_tmp, 0x6
 254        bne     trap_setup_user_stack_is_bolixed
 255         add    %sp, 0x38, %glob_tmp            /* Is second page in vma hole? */
 256
 257        sra     %glob_tmp, 29, %glob_tmp
 258        add     %glob_tmp, 0x1, %glob_tmp
 259        andncc  %glob_tmp, 0x1, %g0
 260        bne     trap_setup_user_stack_is_bolixed
 261         add    %sp, 0x38, %glob_tmp
 262
 263        lda     [%glob_tmp] ASI_PTE, %glob_tmp
 264
 265tsetup_sun4c_onepage:
 266        srl     %glob_tmp, 29, %glob_tmp
 267        cmp     %glob_tmp, 0x6                          ! can user write to it?
 268        bne     trap_setup_user_stack_is_bolixed        ! failure
 269         nop
 270
 271        STORE_WINDOW(sp)
 272
 273        restore %g0, %g0, %g0
 274
 275        jmpl    %t_retpc + 0x8, %g0
 276         mov    %t_kstack, %sp
 277
 278        .globl  tsetup_srmmu_stackchk
 279tsetup_srmmu_stackchk:
 280        /* Check results of callers andcc %sp, 0x7, %g0 */
 281        bne     trap_setup_user_stack_is_bolixed
 282         sethi   %hi(PAGE_OFFSET), %glob_tmp
 283
 284        cmp     %glob_tmp, %sp
 285        bleu,a  1f
 286         lda    [%g0] ASI_M_MMUREGS, %glob_tmp          ! read MMU control
 287
 288trap_setup_user_stack_is_bolixed:
 289        /* From user/kernel into invalid window w/bad user
 290         * stack. Save bad user stack, and return to caller.
 291         */
 292        SAVE_BOLIXED_USER_STACK(curptr, g3)
 293        restore %g0, %g0, %g0
 294
 295        jmpl    %t_retpc + 0x8, %g0
 296         mov    %t_kstack, %sp
 297
 2981:
 299        /* Clear the fault status and turn on the no_fault bit. */
 300        or      %glob_tmp, 0x2, %glob_tmp               ! or in no_fault bit
 301        sta     %glob_tmp, [%g0] ASI_M_MMUREGS          ! set it
 302
 303        /* Dump the registers and cross fingers. */
 304        STORE_WINDOW(sp)
 305
 306        /* Clear the no_fault bit and check the status. */
 307        andn    %glob_tmp, 0x2, %glob_tmp
 308        sta     %glob_tmp, [%g0] ASI_M_MMUREGS
 309        mov     AC_M_SFAR, %glob_tmp
 310        lda     [%glob_tmp] ASI_M_MMUREGS, %g0
 311        mov     AC_M_SFSR, %glob_tmp
 312        lda     [%glob_tmp] ASI_M_MMUREGS, %glob_tmp    ! save away status of winstore
 313        andcc   %glob_tmp, 0x2, %g0                     ! did we fault?
 314        bne     trap_setup_user_stack_is_bolixed        ! failure
 315         nop
 316
 317        restore %g0, %g0, %g0
 318
 319        jmpl    %t_retpc + 0x8, %g0
 320         mov    %t_kstack, %sp
 321
 322