1 files changed, 428 insertions, 0 deletions

diff --git a/arch/sparc/kernel/wof.S b/arch/sparc/kernel/wof.S
new file mode 100644
index 000000000000..083b1215d515
--- /dev/null
+++ b/arch/sparc/kernel/wof.S
@@ -0,0 +1,428 @@
+/* $Id: wof.S,v 1.40 2000/01/08 16:38:18 anton Exp $
+ * wof.S: Sparc window overflow handler.
+ *
+ * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
+ */
+
+#include <asm/contregs.h>
+#include <asm/page.h>
+#include <asm/ptrace.h>
+#include <asm/psr.h>
+#include <asm/smp.h>
+#include <asm/asi.h>
+#include <asm/winmacro.h>
+#include <asm/asmmacro.h>
+#include <asm/thread_info.h>
+
+/* WARNING: This routine is hairy and _very_ complicated, but it
+ *          must be as fast as possible as it handles the allocation
+ *          of register windows to the user and kernel.  If you touch
+ *          this code be _very_ careful as many other pieces of the
+ *          kernel depend upon how this code behaves.  You have been
+ *          duly warned...
+ */
+
+/* We define macro's for registers which have a fixed
+ * meaning throughout this entire routine.  The 'T' in
+ * the comments mean that the register can only be
+ * accessed when in the 'trap' window, 'G' means
+ * accessible in any window.  Do not change these registers
+ * after they have been set, until you are ready to return
+ * from the trap.
+ */
+#define t_psr       l0 /* %psr at trap time                     T */
+#define t_pc        l1 /* PC for trap return                    T */
+#define t_npc       l2 /* NPC for trap return                   T */
+#define t_wim       l3 /* %wim at trap time                     T */
+#define saved_g5    l5 /* Global save register                  T */
+#define saved_g6    l6 /* Global save register                  T */
+#define curptr      g6 /* Gets set to 'current' then stays      G */
+
+/* Now registers whose values can change within the handler.      */
+#define twin_tmp    l4 /* Temp reg, only usable in trap window  T */
+#define glob_tmp    g5 /* Global temporary reg, usable anywhere G */
+
+        .text
+        .align  4
+        /* BEGINNING OF PATCH INSTRUCTIONS */
+        /* On a 7-window Sparc the boot code patches spnwin_*
+         * instructions with the following ones.
+         */
+        .globl  spnwin_patch1_7win, spnwin_patch2_7win, spnwin_patch3_7win
+spnwin_patch1_7win:     sll     %t_wim, 6, %glob_tmp
+spnwin_patch2_7win:     and     %glob_tmp, 0x7f, %glob_tmp
+spnwin_patch3_7win:     and     %twin_tmp, 0x7f, %twin_tmp
+        /* END OF PATCH INSTRUCTIONS */
+
+        /* The trap entry point has done the following:
+         *
+         * rd    %psr, %l0
+         * rd    %wim, %l3
+         * b     spill_window_entry
+         * andcc %l0, PSR_PS, %g0
+         */
+
+        /* Datum current_thread_info->uwinmask contains at all times a bitmask
+         * where if any user windows are active, at least one bit will
+         * be set in to mask.  If no user windows are active, the bitmask
+         * will be all zeroes.
+         */
+        .globl  spill_window_entry 
+        .globl  spnwin_patch1, spnwin_patch2, spnwin_patch3
+spill_window_entry:
+        /* LOCATION: Trap Window */
+
+        mov     %g5, %saved_g5          ! save away global temp register
+        mov     %g6, %saved_g6          ! save away 'current' ptr register
+
+        /* Compute what the new %wim will be if we save the
+         * window properly in this trap handler.
+         *
+         * newwim = ((%wim>>1) | (%wim<<(nwindows - 1)));
+         */
+                srl     %t_wim, 0x1, %twin_tmp
+spnwin_patch1:  sll     %t_wim, 7, %glob_tmp
+                or      %glob_tmp, %twin_tmp, %glob_tmp
+spnwin_patch2:  and     %glob_tmp, 0xff, %glob_tmp
+
+        /* The trap entry point has set the condition codes
+         * up for us to see if this is from user or kernel.
+         * Get the load of 'curptr' out of the way.
+         */
+        LOAD_CURRENT(curptr, twin_tmp)
+
+        andcc   %t_psr, PSR_PS, %g0
+        be,a    spwin_fromuser                          ! all user wins, branch
+         save   %g0, %g0, %g0                           ! Go where saving will occur
+        
+        /* See if any user windows are active in the set. */
+        ld      [%curptr + TI_UWINMASK], %twin_tmp      ! grab win mask
+        orcc    %g0, %twin_tmp, %g0                     ! check for set bits
+        bne     spwin_exist_uwins                       ! yep, there are some
+         andn   %twin_tmp, %glob_tmp, %twin_tmp         ! compute new uwinmask
+
+        /* Save into the window which must be saved and do it.
+         * Basically if we are here, this means that we trapped
+         * from kernel mode with only kernel windows in the register
+         * file.
+         */
+        save    %g0, %g0, %g0           ! save into the window to stash away
+        wr      %glob_tmp, 0x0, %wim    ! set new %wim, this is safe now
+
+spwin_no_userwins_from_kernel:
+        /* LOCATION: Window to be saved */
+
+        STORE_WINDOW(sp)                ! stash the window
+        restore %g0, %g0, %g0           ! go back into trap window
+
+        /* LOCATION: Trap window */
+        mov     %saved_g5, %g5          ! restore %glob_tmp
+        mov     %saved_g6, %g6          ! restore %curptr
+        wr      %t_psr, 0x0, %psr       ! restore condition codes in %psr
+        WRITE_PAUSE                     ! waste some time
+        jmp     %t_pc                   ! Return from trap
+        rett    %t_npc                  ! we are done
+
+spwin_exist_uwins:
+        /* LOCATION: Trap window */
+
+        /* Wow, user windows have to be dealt with, this is dirty
+         * and messy as all hell.  And difficult to follow if you
+         * are approaching the infamous register window trap handling
+         * problem for the first time. DON'T LOOK!
+         *
+         * Note that how the execution path works out, the new %wim
+         * will be left for us in the global temporary register,
+         * %glob_tmp.  We cannot set the new %wim first because we
+         * need to save into the appropriate window without inducing
+         * a trap (traps are off, we'd get a watchdog wheee)...
+         * But first, store the new user window mask calculated
+         * above.
+         */
+        st      %twin_tmp, [%curptr + TI_UWINMASK]
+        save    %g0, %g0, %g0           ! Go to where the saving will occur
+
+spwin_fromuser:
+        /* LOCATION: Window to be saved */
+        wr      %glob_tmp, 0x0, %wim    ! Now it is safe to set new %wim
+
+        /* LOCATION: Window to be saved */
+
+        /* This instruction branches to a routine which will check
+         * to validity of the users stack pointer by whatever means
+         * are necessary.  This means that this is architecture
+         * specific and thus this branch instruction will need to
+         * be patched at boot time once the machine type is known.
+         * This routine _shall not_ touch %curptr under any
+         * circumstances whatsoever!  It will branch back to the
+         * label 'spwin_good_ustack' if the stack is ok but still
+         * needs to be dumped (SRMMU for instance will not need to
+         * do this) or 'spwin_finish_up' if the stack is ok and the
+         * registers have already been saved.  If the stack is found
+         * to be bogus for some reason the routine shall branch to
+         * the label 'spwin_user_stack_is_bolixed' which will take
+         * care of things at that point.
+         */
+        .globl  spwin_mmu_patchme
+spwin_mmu_patchme:      b       spwin_sun4c_stackchk
+                                 andcc  %sp, 0x7, %g0
+
+spwin_good_ustack:
+        /* LOCATION: Window to be saved */
+
+        /* The users stack is ok and we can safely save it at
+         * %sp.
+         */
+        STORE_WINDOW(sp)
+
+spwin_finish_up:
+        restore %g0, %g0, %g0           /* Back to trap window. */
+
+        /* LOCATION: Trap window */
+
+        /* We have spilled successfully, and we have properly stored
+         * the appropriate window onto the stack.
+         */
+
+        /* Restore saved globals */
+        mov     %saved_g5, %g5
+        mov     %saved_g6, %g6
+
+        wr      %t_psr, 0x0, %psr
+        WRITE_PAUSE
+        jmp     %t_pc
+        rett    %t_npc
+
+spwin_user_stack_is_bolixed:
+        /* LOCATION: Window to be saved */
+
+        /* Wheee, user has trashed his/her stack.  We have to decide
+         * how to proceed based upon whether we came from kernel mode
+         * or not.  If we came from kernel mode, toss the window into
+         * a special buffer and proceed, the kernel _needs_ a window
+         * and we could be in an interrupt handler so timing is crucial.
+         * If we came from user land we build a full stack frame and call
+         * c-code to gun down the process.
+         */
+        rd      %psr, %glob_tmp
+        andcc   %glob_tmp, PSR_PS, %g0
+        bne     spwin_bad_ustack_from_kernel
+         nop
+
+        /* Oh well, throw this one window into the per-task window
+         * buffer, the first one.
+         */
+        st      %sp, [%curptr + TI_RWIN_SPTRS]
+        STORE_WINDOW(curptr + TI_REG_WINDOW)
+        restore %g0, %g0, %g0
+
+        /* LOCATION: Trap Window */
+
+        /* Back in the trap window, update winbuffer save count. */
+        mov     1, %twin_tmp
+        st      %twin_tmp, [%curptr + TI_W_SAVED]
+
+                /* Compute new user window mask.  What we are basically
+                 * doing is taking two windows, the invalid one at trap
+                 * time and the one we attempted to throw onto the users
+                 * stack, and saying that everything else is an ok user
+                 * window.  umask = ((~(%t_wim | %wim)) & valid_wim_bits)
+                 */
+                rd      %wim, %twin_tmp
+                or      %twin_tmp, %t_wim, %twin_tmp
+                not     %twin_tmp
+spnwin_patch3:  and     %twin_tmp, 0xff, %twin_tmp      ! patched on 7win Sparcs
+                st      %twin_tmp, [%curptr + TI_UWINMASK]
+
+#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ)
+
+        sethi   %hi(STACK_OFFSET), %sp
+        or      %sp, %lo(STACK_OFFSET), %sp
+        add     %curptr, %sp, %sp
+
+        /* Restore the saved globals and build a pt_regs frame. */
+        mov     %saved_g5, %g5
+        mov     %saved_g6, %g6
+        STORE_PT_ALL(sp, t_psr, t_pc, t_npc, g1)
+
+        sethi   %hi(STACK_OFFSET), %g6
+        or      %g6, %lo(STACK_OFFSET), %g6
+        sub     %sp, %g6, %g6           ! curptr
+
+        /* Turn on traps and call c-code to deal with it. */
+        wr      %t_psr, PSR_ET, %psr
+        nop
+        call    window_overflow_fault
+         nop
+
+        /* Return from trap if C-code actually fixes things, if it
+         * doesn't then we never get this far as the process will
+         * be given the look of death from Commander Peanut.
+         */
+        b       ret_trap_entry
+         clr    %l6
+
+spwin_bad_ustack_from_kernel:
+        /* LOCATION: Window to be saved */
+
+        /* The kernel provoked a spill window trap, but the window we
+         * need to save is a user one and the process has trashed its
+         * stack pointer.  We need to be quick, so we throw it into
+         * a per-process window buffer until we can properly handle
+         * this later on.
+         */
+        SAVE_BOLIXED_USER_STACK(curptr, glob_tmp)
+        restore %g0, %g0, %g0
+
+        /* LOCATION: Trap window */
+
+        /* Restore globals, condition codes in the %psr and
+         * return from trap.  Note, restoring %g6 when returning
+         * to kernel mode is not necessarily these days. ;-)
+         */
+        mov     %saved_g5, %g5
+        mov     %saved_g6, %g6
+
+        wr      %t_psr, 0x0, %psr
+        WRITE_PAUSE
+
+        jmp     %t_pc
+        rett    %t_npc
+
+/* Undefine the register macros which would only cause trouble
+ * if used below.  This helps find 'stupid' coding errors that
+ * produce 'odd' behavior.  The routines below are allowed to
+ * make usage of glob_tmp and t_psr so we leave them defined.
+ */
+#undef twin_tmp
+#undef curptr
+#undef t_pc
+#undef t_npc
+#undef t_wim
+#undef saved_g5
+#undef saved_g6
+
+/* Now come the per-architecture window overflow stack checking routines.
+ * As noted above %curptr cannot be touched by this routine at all.
+ */
+
+        .globl  spwin_sun4c_stackchk
+spwin_sun4c_stackchk:
+        /* LOCATION: Window to be saved on the stack */
+
+        /* See if the stack is in the address space hole but first,
+         * check results of callers andcc %sp, 0x7, %g0
+         */
+        be      1f
+         sra    %sp, 29, %glob_tmp
+
+        rd      %psr, %glob_tmp
+        b       spwin_user_stack_is_bolixed + 0x4
+         nop
+
+1:
+        add     %glob_tmp, 0x1, %glob_tmp
+        andncc  %glob_tmp, 0x1, %g0
+        be      1f
+         and    %sp, 0xfff, %glob_tmp           ! delay slot
+
+        rd      %psr, %glob_tmp
+        b       spwin_user_stack_is_bolixed + 0x4
+         nop
+
+        /* See if our dump area will be on more than one
+         * page.
+         */
+1:
+        add     %glob_tmp, 0x38, %glob_tmp
+        andncc  %glob_tmp, 0xff8, %g0
+        be      spwin_sun4c_onepage             ! only one page to check
+         lda    [%sp] ASI_PTE, %glob_tmp        ! have to check first page anyways
+
+spwin_sun4c_twopages:
+        /* Is first page ok permission wise? */
+        srl     %glob_tmp, 29, %glob_tmp
+        cmp     %glob_tmp, 0x6
+        be      1f
+         add    %sp, 0x38, %glob_tmp    /* Is second page in vma hole? */
+
+        rd      %psr, %glob_tmp
+        b       spwin_user_stack_is_bolixed + 0x4
+         nop
+
+1:
+        sra     %glob_tmp, 29, %glob_tmp
+        add     %glob_tmp, 0x1, %glob_tmp
+        andncc  %glob_tmp, 0x1, %g0
+        be      1f
+         add    %sp, 0x38, %glob_tmp
+
+        rd      %psr, %glob_tmp
+        b       spwin_user_stack_is_bolixed + 0x4
+         nop
+
+1:
+        lda     [%glob_tmp] ASI_PTE, %glob_tmp
+
+spwin_sun4c_onepage:
+        srl     %glob_tmp, 29, %glob_tmp
+        cmp     %glob_tmp, 0x6                          ! can user write to it?
+        be      spwin_good_ustack                       ! success
+         nop
+
+        rd      %psr, %glob_tmp
+        b       spwin_user_stack_is_bolixed + 0x4
+         nop
+
+        /* This is a generic SRMMU routine.  As far as I know this
+         * works for all current v8/srmmu implementations, we'll
+         * see...
+         */
+        .globl  spwin_srmmu_stackchk
+spwin_srmmu_stackchk:
+        /* LOCATION: Window to be saved on the stack */
+
+        /* Because of SMP concerns and speed we play a trick.
+         * We disable fault traps in the MMU control register,
+         * Execute the stores, then check the fault registers
+         * to see what happens.  I can hear Linus now
+         * "disgusting... broken hardware...".
+         *
+         * But first, check to see if the users stack has ended
+         * up in kernel vma, then we would succeed for the 'wrong'
+         * reason... ;(  Note that the 'sethi' below assumes the
+         * kernel is page aligned, which should always be the case.
+         */
+        /* Check results of callers andcc %sp, 0x7, %g0 */
+        bne     spwin_user_stack_is_bolixed
+         sethi   %hi(PAGE_OFFSET), %glob_tmp
+        cmp     %glob_tmp, %sp
+        bleu    spwin_user_stack_is_bolixed
+         mov    AC_M_SFSR, %glob_tmp
+
+        /* Clear the fault status and turn on the no_fault bit. */
+        lda     [%glob_tmp] ASI_M_MMUREGS, %g0          ! eat SFSR
+
+        lda     [%g0] ASI_M_MMUREGS, %glob_tmp          ! read MMU control
+        or      %glob_tmp, 0x2, %glob_tmp               ! or in no_fault bit
+        sta     %glob_tmp, [%g0] ASI_M_MMUREGS          ! set it
+
+        /* Dump the registers and cross fingers. */
+        STORE_WINDOW(sp)
+
+        /* Clear the no_fault bit and check the status. */
+        andn    %glob_tmp, 0x2, %glob_tmp
+        sta     %glob_tmp, [%g0] ASI_M_MMUREGS
+
+        mov     AC_M_SFAR, %glob_tmp
+        lda     [%glob_tmp] ASI_M_MMUREGS, %g0
+
+        mov     AC_M_SFSR, %glob_tmp
+        lda     [%glob_tmp] ASI_M_MMUREGS, %glob_tmp
+        andcc   %glob_tmp, 0x2, %g0                     ! did we fault?
+        be,a    spwin_finish_up + 0x4                   ! cool beans, success
+         restore %g0, %g0, %g0
+
+        rd      %psr, %glob_tmp
+        b       spwin_user_stack_is_bolixed + 0x4       ! we faulted, ugh
+         nop