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
  36 tsetup_7win_patch1:     sll     %t_wim, 0x6, %t_wim
  37 tsetup_7win_patch2:     and     %g2, 0x7f, %g2
  38 tsetup_7win_patch3:     and     %g2, 0x7f, %g2
  39 tsetup_7win_patch4:     and     %g1, 0x7f, %g1
  40 tsetup_7win_patch5:     sll     %t_wim, 0x6, %t_wim
  41 tsetup_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
  77 trap_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
 103 trap_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
 111 tsetup_patch1:
 112         sll     %t_wim, 0x7, %t_wim     ! patched on 7 window Sparcs
 113         or      %t_wim, %g2, %g2
 114 tsetup_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
 132 trap_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
 185 1:
 186         andn    %g2, %t_twinmask, %g2
 187 tsetup_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
 194 trap_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
 201 tsetup_patch4:
 202         and     %g1, 0xff, %g1          ! patched on 7win Sparcs, mask
 203         srl     %t_wim, 0x1, %g2        ! compute new %wim
 204 tsetup_patch5:
 205         sll     %t_wim, 0x7, %t_wim     ! patched on 7win Sparcs
 206         or      %t_wim, %g2, %g2        ! %g2 is new %wim
 207 tsetup_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
 220 tsetup_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
 232 tsetup_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
 250 tsetup_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
 265 tsetup_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
 279 tsetup_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
 288 trap_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
 298 1:
 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