/*
* etrap.S: Sparc trap window preparation for entry into the
* Linux kernel.
*
* Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
*/
#include <asm/head.h>
#include <asm/asi.h>
#include <asm/contregs.h>
#include <asm/page.h>
#include <asm/psr.h>
#include <asm/ptrace.h>
#include <asm/winmacro.h>
#include <asm/asmmacro.h>
#include <asm/thread_info.h>
/* Registers to not touch at all. */
#define t_psr l0 /* Set by caller */
#define t_pc l1 /* Set by caller */
#define t_npc l2 /* Set by caller */
#define t_wim l3 /* Set by caller */
#define t_twinmask l4 /* Set at beginning of this entry routine. */
#define t_kstack l5 /* Set right before pt_regs frame is built */
#define t_retpc l6 /* If you change this, change winmacro.h header file */
#define t_systable l7 /* Never touch this, could be the syscall table ptr. */
#define curptr g6 /* Set after pt_regs frame is built */
.text
.align 4
/* SEVEN WINDOW PATCH INSTRUCTIONS */
.globl tsetup_7win_patch1, tsetup_7win_patch2
.globl tsetup_7win_patch3, tsetup_7win_patch4
.globl tsetup_7win_patch5, tsetup_7win_patch6
tsetup_7win_patch1: sll %t_wim, 0x6, %t_wim
tsetup_7win_patch2: and %g2, 0x7f, %g2
tsetup_7win_patch3: and %g2, 0x7f, %g2
tsetup_7win_patch4: and %g1, 0x7f, %g1
tsetup_7win_patch5: sll %t_wim, 0x6, %t_wim
tsetup_7win_patch6: and %g2, 0x7f, %g2
/* END OF PATCH INSTRUCTIONS */
/* At trap time, interrupts and all generic traps do the
* following:
*
* rd %psr, %l0
* b some_handler
* rd %wim, %l3
* nop
*
* Then 'some_handler' if it needs a trap frame (ie. it has
* to call c-code and the trap cannot be handled in-window)
* then it does the SAVE_ALL macro in entry.S which does
*
* sethi %hi(trap_setup), %l4
* jmpl %l4 + %lo(trap_setup), %l6
* nop
*/
/* 2 3 4 window number
* -----
* O T S mnemonic
*
* O == Current window before trap
* T == Window entered when trap occurred
* S == Window we will need to save if (1<<T) == %wim
*
* Before execution gets here, it must be guaranteed that
* %l0 contains trap time %psr, %l1 and %l2 contain the
* trap pc and npc, and %l3 contains the trap time %wim.
*/
.globl trap_setup, tsetup_patch1, tsetup_patch2
.globl tsetup_patch3, tsetup_patch4
.globl tsetup_patch5, tsetup_patch6
trap_setup:
/* Calculate mask of trap window. See if from user
* or kernel and branch conditionally.
*/
mov 1, %t_twinmask
andcc %t_psr, PSR_PS, %g0 ! fromsupv_p = (psr & PSR_PS)
be trap_setup_from_user ! nope, from user mode
sll %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr)
/* From kernel, allocate more kernel stack and
* build a pt_regs trap frame.
*/
sub %fp, (STACKFRAME_SZ + TRACEREG_SZ), %t_kstack
STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2)
/* See if we are in the trap window. */
andcc %t_twinmask, %t_wim, %g0
bne trap_setup_kernel_spill ! in trap window, clean up
nop
/* Trap from kernel with a window available.
* Just do it...
*/
jmpl %t_retpc + 0x8, %g0 ! return to caller
mov %t_kstack, %sp ! jump onto new stack
trap_setup_kernel_spill:
ld [%curptr + TI_UWINMASK], %g1
orcc %g0, %g1, %g0
bne trap_setup_user_spill ! there are some user windows, yuck
/* Spill from kernel, but only kernel windows, adjust
* %wim and go.
*/
srl %t_wim, 0x1, %g2 ! begin computation of new %wim
tsetup_patch1:
sll %t_wim, 0x7, %t_wim ! patched on 7 window Sparcs
or %t_wim, %g2, %g2
tsetup_patch2:
and %g2, 0xff, %g2 ! patched on 7 window Sparcs
save %g0, %g0, %g0
/* Set new %wim value */
wr %g2, 0x0, %wim
/* Save the kernel window onto the corresponding stack. */
STORE_WINDOW(sp)
restore %g0, %g0, %g0
jmpl %t_retpc + 0x8, %g0 ! return to caller
mov %t_kstack, %sp ! and onto new kernel stack
#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ)
trap_setup_from_user:
/* We can't use %curptr yet. */
LOAD_CURRENT(t_kstack, t_twinmask)
sethi %hi(STACK_OFFSET), %t_twinmask
or %t_twinmask, %lo(STACK_OFFSET), %t_twinmask
add %t_kstack, %t_twinmask, %t_kstack
mov 1, %t_twinmask
sll %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr)
/* Build pt_regs frame. */
STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2)
#if 0
/* If we're sure every task_struct is THREAD_SIZE aligned,
we can speed this up. */
sethi %hi(STACK_OFFSET), %curptr
or %curptr, %lo(STACK_OFFSET), %curptr
sub %t_kstack, %curptr, %curptr
#else
sethi %hi(~(THREAD_SIZE - 1)), %curptr
and %t_kstack, %curptr, %curptr
#endif
/* Clear current_thread_info->w_saved */
st %g0, [%curptr + TI_W_SAVED]
/* See if we are in the trap window. */
andcc %t_twinmask, %t_wim, %g0
bne trap_setup_user_spill ! yep we are
orn %g0, %t_twinmask, %g1 ! negate trap win mask into %g1
/* Trap from user, but not into the invalid window.
* Calculate new umask. The way this works is,
* any window from the %wim at trap time until
* the window right before the one we are in now,
* is a user window. A diagram:
*
* 7 6 5 4 3 2 1 0 window number
* ---------------
* I L T mnemonic
*
* Window 'I' is the invalid window in our example,
* window 'L' is the window the user was in when
* the trap occurred, window T is the trap window
* we are in now. So therefore, windows 5, 4 and
* 3 are user windows. The following sequence
* computes the user winmask to represent this.
*/
subcc %t_wim, %t_twinmask, %g2
bneg,a 1f
sub %g2, 0x1, %g2
1:
andn %g2, %t_twinmask, %g2
tsetup_patch3:
and %g2, 0xff, %g2 ! patched on 7win Sparcs
st %g2, [%curptr + TI_UWINMASK] ! store new umask
jmpl %t_retpc + 0x8, %g0 ! return to caller
mov %t_kstack, %sp ! and onto kernel stack
trap_setup_user_spill:
/* A spill occurred from either kernel or user mode
* and there exist some user windows to deal with.
* A mask of the currently valid user windows
* is in %g1 upon entry to here.
*/
tsetup_patch4:
and %g1, 0xff, %g1 ! patched on 7win Sparcs, mask
srl %t_wim, 0x1, %g2 ! compute new %wim
tsetup_patch5:
sll %t_wim, 0x7, %t_wim ! patched on 7win Sparcs
or %t_wim, %g2, %g2 ! %g2 is new %wim
tsetup_patch6:
and %g2, 0xff, %g2 ! patched on 7win Sparcs
andn %g1, %g2, %g1 ! clear this bit in %g1
st %g1, [%curptr + TI_UWINMASK]
save %g0, %g0, %g0
wr %g2, 0x0, %wim
/* Call MMU-architecture dependent stack checking
* routine.
*/
b tsetup_srmmu_stackchk
andcc %sp, 0x7, %g0
/* Architecture specific stack checking routines. When either
* of these routines are called, the globals are free to use
* as they have been safely stashed on the new kernel stack
* pointer. Thus the definition below for simplicity.
*/
#define glob_tmp g1
.globl tsetup_srmmu_stackchk
tsetup_srmmu_stackchk:
/* Check results of callers andcc %sp, 0x7, %g0 */
bne trap_setup_user_stack_is_bolixed
sethi %hi(PAGE_OFFSET), %glob_tmp
cmp %glob_tmp, %sp
bleu,a 1f
lda [%g0] ASI_M_MMUREGS, %glob_tmp ! read MMU control
trap_setup_user_stack_is_bolixed:
/* From user/kernel into invalid window w/bad user
* stack. Save bad user stack, and return to caller.
*/
SAVE_BOLIXED_USER_STACK(curptr, g3)
restore %g0, %g0, %g0
jmpl %t_retpc + 0x8, %g0
mov %t_kstack, %sp
1:
/* Clear the fault status and turn on the no_fault bit. */
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 ! save away status of winstore
andcc %glob_tmp, 0x2, %g0 ! did we fault?
bne trap_setup_user_stack_is_bolixed ! failure
nop
restore %g0, %g0, %g0
jmpl %t_retpc + 0x8, %g0
mov %t_kstack, %sp
