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#
# Copyright (C) 2005 Jakub Jermar
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# - The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
/**
* This file contains kernel trap table.
*/
.register %g2, #scratch
.register %g3, #scratch
.text
#include <arch/trap/trap_table.h>
#include <arch/trap/regwin.h>
#include <arch/trap/interrupt.h>
#include <arch/trap/exception.h>
#include <arch/trap/mmu.h>
#include <arch/mm/mmu.h>
#include <arch/mm/page.h>
#include <arch/stack.h>
#include <arch/regdef.h>
#define TABLE_SIZE TRAP_TABLE_SIZE
#define ENTRY_SIZE TRAP_TABLE_ENTRY_SIZE
/*
* Kernel trap table.
*/
.align TABLE_SIZE
.global trap_table
trap_table:
/* TT = 0x08, TL = 0, instruction_access_exception */
.org trap_table + TT_INSTRUCTION_ACCESS_EXCEPTION*ENTRY_SIZE
.global instruction_access_exception
instruction_access_exception:
PREEMPTIBLE_HANDLER do_instruction_access_exc
/* TT = 0x10, TL = 0, illegal_instruction */
.org trap_table + TT_ILLEGAL_INSTRUCTION*ENTRY_SIZE
.global illegal_instruction
illegal_instruction:
PREEMPTIBLE_HANDLER do_illegal_instruction
/* TT = 0x24, TL = 0, clean_window handler */
.org trap_table + TT_CLEAN_WINDOW*ENTRY_SIZE
.global clean_window_handler
clean_window_handler:
CLEAN_WINDOW_HANDLER
/* TT = 0x32, TL = 0, data_access_error */
.org trap_table + TT_DATA_ACCESS_ERROR*ENTRY_SIZE
.global data_access_error
data_access_error:
PREEMPTIBLE_HANDLER do_data_access_error
/* TT = 0x34, TL = 0, mem_address_not_aligned */
.org trap_table + TT_MEM_ADDRESS_NOT_ALIGNED*ENTRY_SIZE
.global mem_address_not_aligned
mem_address_not_aligned:
PREEMPTIBLE_HANDLER do_mem_address_not_aligned
/* TT = 0x41, TL = 0, interrupt_level_1 handler */
.org trap_table + TT_INTERRUPT_LEVEL_1*ENTRY_SIZE
.global interrupt_level_1_handler
interrupt_level_1_handler:
INTERRUPT_LEVEL_N_HANDLER 1
/* TT = 0x42, TL = 0, interrupt_level_2 handler */
.org trap_table + TT_INTERRUPT_LEVEL_2*ENTRY_SIZE
.global interrupt_level_2_handler
interrupt_level_2_handler:
INTERRUPT_LEVEL_N_HANDLER 2
/* TT = 0x43, TL = 0, interrupt_level_3 handler */
.org trap_table + TT_INTERRUPT_LEVEL_3*ENTRY_SIZE
.global interrupt_level_3_handler
interrupt_level_3_handler:
INTERRUPT_LEVEL_N_HANDLER 3
/* TT = 0x44, TL = 0, interrupt_level_4 handler */
.org trap_table + TT_INTERRUPT_LEVEL_4*ENTRY_SIZE
.global interrupt_level_4_handler
interrupt_level_4_handler:
INTERRUPT_LEVEL_N_HANDLER 4
/* TT = 0x45, TL = 0, interrupt_level_5 handler */
.org trap_table + TT_INTERRUPT_LEVEL_5*ENTRY_SIZE
.global interrupt_level_5_handler
interrupt_level_5_handler:
INTERRUPT_LEVEL_N_HANDLER 5
/* TT = 0x46, TL = 0, interrupt_level_6 handler */
.org trap_table + TT_INTERRUPT_LEVEL_6*ENTRY_SIZE
.global interrupt_level_6_handler
interrupt_level_6_handler:
INTERRUPT_LEVEL_N_HANDLER 6
/* TT = 0x47, TL = 0, interrupt_level_7 handler */
.org trap_table + TT_INTERRUPT_LEVEL_7*ENTRY_SIZE
.global interrupt_level_7_handler
interrupt_level_7_handler:
INTERRUPT_LEVEL_N_HANDLER 7
/* TT = 0x48, TL = 0, interrupt_level_8 handler */
.org trap_table + TT_INTERRUPT_LEVEL_8*ENTRY_SIZE
.global interrupt_level_8_handler
interrupt_level_8_handler:
INTERRUPT_LEVEL_N_HANDLER 8
/* TT = 0x49, TL = 0, interrupt_level_9 handler */
.org trap_table + TT_INTERRUPT_LEVEL_9*ENTRY_SIZE
.global interrupt_level_9_handler
interrupt_level_9_handler:
INTERRUPT_LEVEL_N_HANDLER 9
/* TT = 0x4a, TL = 0, interrupt_level_10 handler */
.org trap_table + TT_INTERRUPT_LEVEL_10*ENTRY_SIZE
.global interrupt_level_10_handler
interrupt_level_10_handler:
INTERRUPT_LEVEL_N_HANDLER 10
/* TT = 0x4b, TL = 0, interrupt_level_11 handler */
.org trap_table + TT_INTERRUPT_LEVEL_11*ENTRY_SIZE
.global interrupt_level_11_handler
interrupt_level_11_handler:
INTERRUPT_LEVEL_N_HANDLER 11
/* TT = 0x4c, TL = 0, interrupt_level_12 handler */
.org trap_table + TT_INTERRUPT_LEVEL_12*ENTRY_SIZE
.global interrupt_level_12_handler
interrupt_level_12_handler:
INTERRUPT_LEVEL_N_HANDLER 12
/* TT = 0x4d, TL = 0, interrupt_level_13 handler */
.org trap_table + TT_INTERRUPT_LEVEL_13*ENTRY_SIZE
.global interrupt_level_13_handler
interrupt_level_13_handler:
INTERRUPT_LEVEL_N_HANDLER 13
/* TT = 0x4e, TL = 0, interrupt_level_14 handler */
.org trap_table + TT_INTERRUPT_LEVEL_14*ENTRY_SIZE
.global interrupt_level_14_handler
interrupt_level_14_handler:
INTERRUPT_LEVEL_N_HANDLER 14
/* TT = 0x4f, TL = 0, interrupt_level_15 handler */
.org trap_table + TT_INTERRUPT_LEVEL_15*ENTRY_SIZE
.global interrupt_level_15_handler
interrupt_level_15_handler:
INTERRUPT_LEVEL_N_HANDLER 15
/* TT = 0x60, TL = 0, interrupt_vector_trap handler */
.org trap_table + TT_INTERRUPT_VECTOR_TRAP*ENTRY_SIZE
.global interrupt_vector_trap_handler
interrupt_vector_trap_handler:
INTERRUPT_VECTOR_TRAP_HANDLER
/* TT = 0x64, TL = 0, fast_instruction_access_MMU_miss */
.org trap_table + TT_FAST_INSTRUCTION_ACCESS_MMU_MISS*ENTRY_SIZE
.global fast_instruction_access_mmu_miss_handler
fast_instruction_access_mmu_miss_handler:
FAST_INSTRUCTION_ACCESS_MMU_MISS_HANDLER
/* TT = 0x68, TL = 0, fast_data_access_MMU_miss */
.org trap_table + TT_FAST_DATA_ACCESS_MMU_MISS*ENTRY_SIZE
.global fast_data_access_mmu_miss_handler
fast_data_access_mmu_miss_handler:
FAST_DATA_ACCESS_MMU_MISS_HANDLER
/* TT = 0x6c, TL = 0, fast_data_access_protection */
.org trap_table + TT_FAST_DATA_ACCESS_PROTECTION*ENTRY_SIZE
.global fast_data_access_protection_handler
fast_data_access_protection_handler:
FAST_DATA_ACCESS_PROTECTION_HANDLER
/* TT = 0x80, TL = 0, spill_0_normal handler */
.org trap_table + TT_SPILL_0_NORMAL*ENTRY_SIZE
.global spill_0_normal
spill_0_normal:
SPILL_NORMAL_HANDLER_KERNEL
/* TT = 0x84, TL = 0, spill_1_normal handler */
.org trap_table + TT_SPILL_1_NORMAL*ENTRY_SIZE
.global spill_1_normal
spill_1_normal:
SPILL_NORMAL_HANDLER_USERSPACE
/* TT = 0x88, TL = 0, spill_2_normal handler */
.org trap_table + TT_SPILL_2_NORMAL*ENTRY_SIZE
.global spill_2_normal
spill_2_normal:
SPILL_TO_USPACE_WINDOW_BUFFER
/* TT = 0xc0, TL = 0, fill_0_normal handler */
.org trap_table + TT_FILL_0_NORMAL*ENTRY_SIZE
.global fill_0_normal
fill_0_normal:
FILL_NORMAL_HANDLER_KERNEL
/* TT = 0xc4, TL = 0, fill_1_normal handler */
.org trap_table + TT_FILL_1_NORMAL*ENTRY_SIZE
.global fill_1_normal
fill_1_normal:
FILL_NORMAL_HANDLER_USERSPACE
/*
* Handlers for TL>0.
*/
/* TT = 0x08, TL > 0, instruction_access_exception */
.org trap_table + (TT_INSTRUCTION_ACCESS_EXCEPTION+512)*ENTRY_SIZE
.global instruction_access_exception_high
instruction_access_exception_high:
PREEMPTIBLE_HANDLER do_instruction_access_exc
/* TT = 0x10, TL > 0, illegal_instruction */
.org trap_table + (TT_ILLEGAL_INSTRUCTION+512)*ENTRY_SIZE
.global illegal_instruction_high
illegal_instruction_high:
PREEMPTIBLE_HANDLER do_illegal_instruction
/* TT = 0x24, TL > 0, clean_window handler */
.org trap_table + (TT_CLEAN_WINDOW+512)*ENTRY_SIZE
.global clean_window_handler_high
clean_window_handler_high:
CLEAN_WINDOW_HANDLER
/* TT = 0x32, TL > 0, data_access_error */
.org trap_table + (TT_DATA_ACCESS_ERROR+512)*ENTRY_SIZE
.global data_access_error_high
data_access_error_high:
PREEMPTIBLE_HANDLER do_data_access_error
/* TT = 0x34, TL > 0, mem_address_not_aligned */
.org trap_table + (TT_MEM_ADDRESS_NOT_ALIGNED+512)*ENTRY_SIZE
.global mem_address_not_aligned_high
mem_address_not_aligned_high:
PREEMPTIBLE_HANDLER do_mem_address_not_aligned
/* TT = 0x64, TL > 0, fast_instruction_access_MMU_miss */
.org trap_table + (TT_FAST_INSTRUCTION_ACCESS_MMU_MISS+512)*ENTRY_SIZE
.global fast_instruction_access_mmu_miss_handler_high
fast_instruction_access_mmu_miss_handler_high:
FAST_INSTRUCTION_ACCESS_MMU_MISS_HANDLER
/* TT = 0x68, TL > 0, fast_data_access_MMU_miss */
.org trap_table + (TT_FAST_DATA_ACCESS_MMU_MISS+512)*ENTRY_SIZE
.global fast_data_access_mmu_miss_handler_high
fast_data_access_mmu_miss_handler_high:
FAST_DATA_ACCESS_MMU_MISS_HANDLER
/* TT = 0x6c, TL > 0, fast_data_access_protection */
.org trap_table + (TT_FAST_DATA_ACCESS_PROTECTION+512)*ENTRY_SIZE
.global fast_data_access_protection_handler_high
fast_data_access_protection_handler_high:
FAST_DATA_ACCESS_PROTECTION_HANDLER
/* TT = 0x80, TL > 0, spill_0_normal handler */
.org trap_table + (TT_SPILL_0_NORMAL+512)*ENTRY_SIZE
.global spill_0_normal_high
spill_0_normal_high:
SPILL_NORMAL_HANDLER_KERNEL
/* TT = 0x88, TL > 0, spill_2_normal handler */
.org trap_table + (TT_SPILL_2_NORMAL+512)*ENTRY_SIZE
.global spill_2_normal_high
spill_2_normal_high:
SPILL_TO_USPACE_WINDOW_BUFFER
/* TT = 0xa0, TL > 0, spill_0_other handler */
.org trap_table + (TT_SPILL_0_OTHER+512)*ENTRY_SIZE
.global spill_0_other_high
spill_0_other_high:
SPILL_TO_USPACE_WINDOW_BUFFER
/* TT = 0xc0, TL > 0, fill_0_normal handler */
.org trap_table + (TT_FILL_0_NORMAL+512)*ENTRY_SIZE
.global fill_0_normal_high
fill_0_normal_high:
FILL_NORMAL_HANDLER_KERNEL
/* Preemptible trap handler for TL=1.
*
* This trap handler makes arrangements to make calling of scheduler() from
* within a trap context possible. It is called from several other trap
* handlers.
*
* This function can be entered either with interrupt globals or alternate globals.
* Memory management trap handlers are obliged to switch to one of those global sets
* prior to calling this function. Register window management functions are not
* allowed to modify the alternate global registers.
*
* Input registers:
* %g1 Address of function to call.
* %g2 Argument for the function.
* %g6 Pre-set as kernel stack base if trap from userspace.
* %g7 Pre-set as address of the userspace window buffer.
*/
.global preemptible_handler
preemptible_handler:
rdpr %tstate, %g3
andcc %g3, TSTATE_PRIV_BIT, %g0 ! if this trap came from the privileged mode...
bnz 0f ! ...skip setting of kernel stack and primary context
nop
/*
* Normal window spills will go to the userspace window buffer.
*/
wrpr %g0, WSTATE_OTHER(0) | WSTATE_NORMAL(2), %wstate
/*
* Switch to kernel stack. The old stack is
* automatically saved in the old window's %sp
* and the new window's %fp.
*/
save %g6, -PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE, %sp
/*
* Mark the CANSAVE windows as OTHER windows.
* Set CLEANWIN to NWINDOW-1 so that clean_window traps do not occur.
*/
rdpr %cansave, %l0
wrpr %l0, %otherwin
wrpr %g0, %cansave
wrpr %g0, NWINDOW - 1, %cleanwin
/*
* Switch to primary context 0.
*/
mov VA_PRIMARY_CONTEXT_REG, %l0
stxa %g0, [%l0] ASI_DMMU
rd %pc, %l0
flush %l0
ba 1f
nop
0:
save %sp, -PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE, %sp
/*
* At this moment, we are using the kernel stack
* and have successfully allocated a register window.
*/
1:
/*
* Other window spills will go to the userspace window buffer
* and normal spills will go to the kernel stack.
*/
wrpr %g0, WSTATE_OTHER(0) | WSTATE_NORMAL(0), %wstate
/*
* Copy arguments.
*/
mov %g1, %l0
mov %g2, %o0
/*
* Save TSTATE, TPC and TNPC aside.
*/
rdpr %tstate, %g1
rdpr %tpc, %g2
rdpr %tnpc, %g3
/*
* The following memory accesses will not fault
* because special provisions are made to have
* the kernel stack of THREAD locked in DTLB.
*/
stx %g1, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TSTATE]
stx %g2, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TPC]
stx %g3, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TNPC]
wrpr %g0, 0, %tl
wrpr %g0, PSTATE_PRIV_BIT, %pstate
SAVE_GLOBALS
/*
* Call the higher-level handler and pass istate as second parameter.
*/
call %l0
add %sp, PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TNPC, %o1
RESTORE_GLOBALS
wrpr %g0, PSTATE_AG_BIT | PSTATE_PRIV_BIT, %pstate
wrpr %g0, 1, %tl
/*
* Read TSTATE, TPC and TNPC from saved copy.
*/
ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TSTATE], %g1
ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TPC], %g2
ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TNPC], %g3
/*
* Restore TSTATE, TPC and TNPC from saved copies.
*/
wrpr %g1, 0, %tstate
wrpr %g2, 0, %tpc
wrpr %g3, 0, %tnpc
/*
* If OTHERWIN is zero, then all the userspace windows have been
* spilled to kernel memory (i.e. register window buffer). If
* OTHERWIN is non-zero, then some userspace windows are still
* valid. Others might have been spilled. However, the CWP pointer
* needs no fixing because the scheduler had not been called.
*/
rdpr %otherwin, %l0
brnz %l0, 0f
nop
/*
* OTHERWIN == 0
*/
/*
* If TSTATE.CWP + 1 == CWP, then we still do not have to fix CWP.
*/
and %g1, TSTATE_CWP_MASK, %l0
inc %l0
and %l0, TSTATE_CWP_MASK, %l0 ! %l0 mod NWINDOW
rdpr %cwp, %l1
cmp %l0, %l1
bz 0f ! CWP is ok
nop
/*
* Fix CWP.
* Just for reminder, the input registers in the current window
* are the output registers of the window to which we want to
* restore. Because the fill trap fills only input and local
* registers of a window, we need to preserve those output
* registers manually.
*/
flushw
mov %sp, %g2
stx %i0, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I0]
stx %i1, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I1]
stx %i2, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I2]
stx %i3, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I3]
stx %i4, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I4]
stx %i5, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I5]
stx %i6, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I6]
stx %i7, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I7]
wrpr %l0, 0, %cwp
mov %g2, %sp
ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I0], %i0
ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I1], %i1
ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I2], %i2
ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I3], %i3
ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I4], %i4
ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I5], %i5
ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I6], %i6
ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_I7], %i7
/*
* OTHERWIN != 0 or fall-through from the OTHERWIN == 0 case.
* The CWP has already been restored to the value it had prior to the SAVE
* at the beginning of this function.
*/
0:
rdpr %tstate, %g1
andcc %g1, TSTATE_PRIV_BIT, %g0 ! if we are not returning to userspace...,
bnz 1f ! ...skip restoring userspace windows
nop
/*
* Spills and fills will be processed by the {spill,fill}_1_normal
* handlers.
*/
wrpr %g0, WSTATE_OTHER(0) | WSTATE_NORMAL(1), %wstate
/*
* Set primary context according to secondary context.
*/
wr %g0, ASI_DMMU, %asi
ldxa [VA_SECONDARY_CONTEXT_REG] %asi, %g1
stxa %g1, [VA_PRIMARY_CONTEXT_REG] %asi
flush %o7
rdpr %cwp, %g1
rdpr %otherwin, %g2
/*
* Skip all OTHERWIN windows and descend to the first window
* in the userspace window buffer.
*/
sub %g1, %g2, %g3
dec %g3
and %g3, NWINDOW - 1, %g3
wrpr %g3, 0, %cwp
/*
* CWP is now in the window last saved in the userspace window buffer.
* Fill all windows stored in the buffer.
*/
clr %g4
0: andcc %g7, PAGE_WIDTH - 1, %g0 ! PAGE_SIZE alignment check
bz 0f ! %g7 is page-aligned, no more windows to refill
nop
add %g7, -STACK_WINDOW_SAVE_AREA_SIZE, %g7
ldx [%g7 + L0_OFFSET], %l0
ldx [%g7 + L1_OFFSET], %l1
ldx [%g7 + L2_OFFSET], %l2
ldx [%g7 + L3_OFFSET], %l3
ldx [%g7 + L4_OFFSET], %l4
ldx [%g7 + L5_OFFSET], %l5
ldx [%g7 + L6_OFFSET], %l6
ldx [%g7 + L7_OFFSET], %l7
ldx [%g7 + I0_OFFSET], %i0
ldx [%g7 + I1_OFFSET], %i1
ldx [%g7 + I2_OFFSET], %i2
ldx [%g7 + I3_OFFSET], %i3
ldx [%g7 + I4_OFFSET], %i4
ldx [%g7 + I5_OFFSET], %i5
ldx [%g7 + I6_OFFSET], %i6
ldx [%g7 + I7_OFFSET], %i7
dec %g3
and %g3, NWINDOW - 1, %g3
wrpr %g3, 0, %cwp ! switch to the preceeding window
ba 0b
inc %g4
0:
/*
* Switch back to the proper current window and adjust
* OTHERWIN, CANRESTORE, CANSAVE and CLEANWIN.
*/
wrpr %g1, 0, %cwp
add %g4, %g2, %g2
cmp %g2, NWINDOW - 2
bg 2f ! fix the CANRESTORE=NWINDOW-1 anomaly
mov NWINDOW - 2, %g1 ! use dealy slot for both cases
sub %g1, %g2, %g1
wrpr %g0, 0, %otherwin
wrpr %g1, 0, %cansave ! NWINDOW - 2 - CANRESTORE
wrpr %g2, 0, %canrestore ! OTHERWIN + windows in the buffer
wrpr %g2, 0, %cleanwin ! avoid information leak
1:
restore
retry
/*
* We got here in order to avoid inconsistency of the window state registers.
* If the:
*
* save %g6, -PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE, %sp
*
* instruction trapped and spilled a register window into the userspace
* window buffer, we have just restored NWINDOW - 1 register windows.
* However, CANRESTORE can be only NWINDOW - 2 at most.
*
* The solution is to manually switch to (CWP - 1) mod NWINDOW
* and set the window state registers so that:
*
* CANRESTORE = NWINDOW - 2
* CLEANWIN = NWINDOW - 2
* CANSAVE = 0
* OTHERWIN = 0
*
* The RESTORE isntruction is therfore to be skipped.
*/
2:
wrpr %g0, 0, %otherwin
wrpr %g0, 0, %cansave
wrpr %g1, 0, %canrestore
wrpr %g1, 0, %cleanwin
rdpr %cwp, %g1
dec %g1
and %g1, NWINDOW - 1, %g1
wrpr %g1, 0, %cwp ! CWP--
retry