LXR linux/arch/sparc/kernel/etrap

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * etrap.S: Sparc trap window preparation for entry into the
   4 *          Linux kernel.
   5 *
   6 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   7 */
   8
   9#include <asm/head.h>
  10#include <asm/asi.h>
  11#include <asm/contregs.h>
  12#include <asm/page.h>
  13#include <asm/psr.h>
  14#include <asm/ptrace.h>
  15#include <asm/winmacro.h>
  16#include <asm/asmmacro.h>
  17#include <asm/thread_info.h>
  18
  19/* Registers to not touch at all. */
  20#define t_psr        l0 /* Set by caller */
  21#define t_pc         l1 /* Set by caller */
  22#define t_npc        l2 /* Set by caller */
  23#define t_wim        l3 /* Set by caller */
  24#define t_twinmask   l4 /* Set at beginning of this entry routine. */
  25#define t_kstack     l5 /* Set right before pt_regs frame is built */
  26#define t_retpc      l6 /* If you change this, change winmacro.h header file */
  27#define t_systable   l7 /* Never touch this, could be the syscall table ptr. */
  28#define curptr       g6 /* Set after pt_regs frame is built */
  29
  30        .text
  31        .align 4
  32
  33        /* SEVEN WINDOW PATCH INSTRUCTIONS */
  34        .globl  tsetup_7win_patch1, tsetup_7win_patch2
  35        .globl  tsetup_7win_patch3, tsetup_7win_patch4
  36        .globl  tsetup_7win_patch5, tsetup_7win_patch6
  37tsetup_7win_patch1:     sll     %t_wim, 0x6, %t_wim
  38tsetup_7win_patch2:     and     %g2, 0x7f, %g2
  39tsetup_7win_patch3:     and     %g2, 0x7f, %g2
  40tsetup_7win_patch4:     and     %g1, 0x7f, %g1
  41tsetup_7win_patch5:     sll     %t_wim, 0x6, %t_wim
  42tsetup_7win_patch6:     and     %g2, 0x7f, %g2
  43        /* END OF PATCH INSTRUCTIONS */
  44
  45        /* At trap time, interrupts and all generic traps do the
  46         * following:
  47         *
  48         * rd   %psr, %l0
  49         * b    some_handler
  50         * rd   %wim, %l3
  51         * nop
  52         *
  53         * Then 'some_handler' if it needs a trap frame (ie. it has
  54         * to call c-code and the trap cannot be handled in-window)
  55         * then it does the SAVE_ALL macro in entry.S which does
  56         *
  57         * sethi        %hi(trap_setup), %l4
  58         * jmpl         %l4 + %lo(trap_setup), %l6
  59         * nop
  60         */
  61
  62        /* 2 3 4  window number
  63         * -----
  64         * O T S  mnemonic
  65         *
  66         * O == Current window before trap
  67         * T == Window entered when trap occurred
  68         * S == Window we will need to save if (1<<T) == %wim
  69         *
  70         * Before execution gets here, it must be guaranteed that
  71         * %l0 contains trap time %psr, %l1 and %l2 contain the
  72         * trap pc and npc, and %l3 contains the trap time %wim.
  73         */
  74
  75        .globl  trap_setup, tsetup_patch1, tsetup_patch2
  76        .globl  tsetup_patch3, tsetup_patch4
  77        .globl  tsetup_patch5, tsetup_patch6
  78trap_setup:
  79        /* Calculate mask of trap window.  See if from user
  80         * or kernel and branch conditionally.
  81         */
  82        mov     1, %t_twinmask
  83        andcc   %t_psr, PSR_PS, %g0              ! fromsupv_p = (psr & PSR_PS)
  84        be      trap_setup_from_user             ! nope, from user mode
  85         sll    %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr)
  86
  87        /* From kernel, allocate more kernel stack and
  88         * build a pt_regs trap frame.
  89         */
  90        sub     %fp, (STACKFRAME_SZ + TRACEREG_SZ), %t_kstack
  91        STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2)
  92
  93        /* See if we are in the trap window. */
  94        andcc   %t_twinmask, %t_wim, %g0
  95        bne     trap_setup_kernel_spill         ! in trap window, clean up
  96         nop
  97
  98        /* Trap from kernel with a window available.
  99         * Just do it...
 100         */
 101        jmpl    %t_retpc + 0x8, %g0     ! return to caller
 102         mov    %t_kstack, %sp          ! jump onto new stack
 103
 104trap_setup_kernel_spill:
 105        ld      [%curptr + TI_UWINMASK], %g1
 106        orcc    %g0, %g1, %g0
 107        bne     trap_setup_user_spill   ! there are some user windows, yuck
 108        /* Spill from kernel, but only kernel windows, adjust
 109         * %wim and go.
 110         */
 111         srl    %t_wim, 0x1, %g2        ! begin computation of new %wim
 112tsetup_patch1:
 113        sll     %t_wim, 0x7, %t_wim     ! patched on 7 window Sparcs
 114        or      %t_wim, %g2, %g2
 115tsetup_patch2:
 116        and     %g2, 0xff, %g2          ! patched on 7 window Sparcs
 117
 118        save    %g0, %g0, %g0
 119
 120        /* Set new %wim value */
 121        wr      %g2, 0x0, %wim
 122
 123        /* Save the kernel window onto the corresponding stack. */
 124        STORE_WINDOW(sp)
 125
 126        restore %g0, %g0, %g0
 127
 128        jmpl    %t_retpc + 0x8, %g0     ! return to caller
 129         mov    %t_kstack, %sp          ! and onto new kernel stack
 130
 131#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ)
 132
 133trap_setup_from_user:
 134        /* We can't use %curptr yet. */
 135        LOAD_CURRENT(t_kstack, t_twinmask)
 136
 137        sethi   %hi(STACK_OFFSET), %t_twinmask
 138        or      %t_twinmask, %lo(STACK_OFFSET), %t_twinmask
 139        add     %t_kstack, %t_twinmask, %t_kstack
 140
 141        mov     1, %t_twinmask
 142        sll     %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr)
 143
 144        /* Build pt_regs frame. */
 145        STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2)
 146
 147#if 0
 148        /* If we're sure every task_struct is THREAD_SIZE aligned,
 149           we can speed this up. */
 150        sethi   %hi(STACK_OFFSET), %curptr
 151        or      %curptr, %lo(STACK_OFFSET), %curptr
 152        sub     %t_kstack, %curptr, %curptr
 153#else
 154        sethi   %hi(~(THREAD_SIZE - 1)), %curptr
 155        and     %t_kstack, %curptr, %curptr
 156#endif
 157
 158        /* Clear current_thread_info->w_saved */
 159        st      %g0, [%curptr + TI_W_SAVED]
 160
 161        /* See if we are in the trap window. */
 162        andcc   %t_twinmask, %t_wim, %g0
 163        bne     trap_setup_user_spill           ! yep we are
 164         orn    %g0, %t_twinmask, %g1           ! negate trap win mask into %g1
 165
 166        /* Trap from user, but not into the invalid window.
 167         * Calculate new umask.  The way this works is,
 168         * any window from the %wim at trap time until
 169         * the window right before the one we are in now,
 170         * is a user window.  A diagram:
 171         *
 172         *      7 6 5 4 3 2 1 0    window number
 173         *      ---------------
 174         *        I     L T        mnemonic
 175         *
 176         * Window 'I' is the invalid window in our example,
 177         * window 'L' is the window the user was in when
 178         * the trap occurred, window T is the trap window
 179         * we are in now.  So therefore, windows 5, 4 and
 180         * 3 are user windows.  The following sequence
 181         * computes the user winmask to represent this.
 182         */
 183        subcc   %t_wim, %t_twinmask, %g2
 184        bneg,a  1f
 185         sub    %g2, 0x1, %g2
 1861:
 187        andn    %g2, %t_twinmask, %g2
 188tsetup_patch3:
 189        and     %g2, 0xff, %g2                  ! patched on 7win Sparcs
 190        st      %g2, [%curptr + TI_UWINMASK]    ! store new umask
 191
 192        jmpl    %t_retpc + 0x8, %g0             ! return to caller
 193         mov    %t_kstack, %sp                  ! and onto kernel stack
 194
 195trap_setup_user_spill:
 196        /* A spill occurred from either kernel or user mode
 197         * and there exist some user windows to deal with.
 198         * A mask of the currently valid user windows
 199         * is in %g1 upon entry to here.
 200         */
 201
 202tsetup_patch4:
 203        and     %g1, 0xff, %g1          ! patched on 7win Sparcs, mask
 204        srl     %t_wim, 0x1, %g2        ! compute new %wim
 205tsetup_patch5:
 206        sll     %t_wim, 0x7, %t_wim     ! patched on 7win Sparcs
 207        or      %t_wim, %g2, %g2        ! %g2 is new %wim
 208tsetup_patch6:
 209        and     %g2, 0xff, %g2          ! patched on 7win Sparcs
 210        andn    %g1, %g2, %g1           ! clear this bit in %g1
 211        st      %g1, [%curptr + TI_UWINMASK]
 212
 213        save    %g0, %g0, %g0
 214
 215        wr      %g2, 0x0, %wim
 216
 217        /* Call MMU-architecture dependent stack checking
 218         * routine.
 219         */
 220        b       tsetup_srmmu_stackchk
 221         andcc  %sp, 0x7, %g0
 222
 223        /* Architecture specific stack checking routines.  When either
 224         * of these routines are called, the globals are free to use
 225         * as they have been safely stashed on the new kernel stack
 226         * pointer.  Thus the definition below for simplicity.
 227         */
 228#define glob_tmp     g1
 229
 230        .globl  tsetup_srmmu_stackchk
 231tsetup_srmmu_stackchk:
 232        /* Check results of callers andcc %sp, 0x7, %g0 */
 233        bne     trap_setup_user_stack_is_bolixed
 234         sethi   %hi(PAGE_OFFSET), %glob_tmp
 235
 236        cmp     %glob_tmp, %sp
 237        bleu,a  1f
 238LEON_PI( lda    [%g0] ASI_LEON_MMUREGS, %glob_tmp)      ! read MMU control
 239SUN_PI_( lda    [%g0] ASI_M_MMUREGS, %glob_tmp)         ! read MMU control
 240
 241trap_setup_user_stack_is_bolixed:
 242        /* From user/kernel into invalid window w/bad user
 243         * stack. Save bad user stack, and return to caller.
 244         */
 245        SAVE_BOLIXED_USER_STACK(curptr, g3)
 246        restore %g0, %g0, %g0
 247
 248        jmpl    %t_retpc + 0x8, %g0
 249         mov    %t_kstack, %sp
 250
 2511:
 252        /* Clear the fault status and turn on the no_fault bit. */
 253        or      %glob_tmp, 0x2, %glob_tmp               ! or in no_fault bit
 254LEON_PI(sta     %glob_tmp, [%g0] ASI_LEON_MMUREGS)              ! set it
 255SUN_PI_(sta     %glob_tmp, [%g0] ASI_M_MMUREGS)         ! set it
 256
 257        /* Dump the registers and cross fingers. */
 258        STORE_WINDOW(sp)
 259
 260        /* Clear the no_fault bit and check the status. */
 261        andn    %glob_tmp, 0x2, %glob_tmp
 262LEON_PI(sta     %glob_tmp, [%g0] ASI_LEON_MMUREGS)
 263SUN_PI_(sta     %glob_tmp, [%g0] ASI_M_MMUREGS)
 264
 265        mov     AC_M_SFAR, %glob_tmp
 266LEON_PI(lda     [%glob_tmp] ASI_LEON_MMUREGS, %g0)
 267SUN_PI_(lda     [%glob_tmp] ASI_M_MMUREGS, %g0)
 268
 269        mov     AC_M_SFSR, %glob_tmp
 270LEON_PI(lda     [%glob_tmp] ASI_LEON_MMUREGS, %glob_tmp)! save away status of winstore
 271SUN_PI_(lda     [%glob_tmp] ASI_M_MMUREGS, %glob_tmp)   ! save away status of winstore
 272
 273        andcc   %glob_tmp, 0x2, %g0                     ! did we fault?
 274        bne     trap_setup_user_stack_is_bolixed        ! failure
 275         nop
 276
 277        restore %g0, %g0, %g0
 278
 279        jmpl    %t_retpc + 0x8, %g0
 280         mov    %t_kstack, %sp
 281
 282