source: mainline/kernel/arch/sparc64/src/trap/trap_table.S@ 3b8fe85

#
# 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.
#

/**
 * @file
 * @brief 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/syscall.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_tl0
instruction_access_exception_tl0:
        wrpr %g0, PSTATE_AG_BIT | PSTATE_PRIV_BIT, %pstate
        PREEMPTIBLE_HANDLER instruction_access_exception

/* TT = 0x0a, TL = 0, instruction_access_error */
.org trap_table + TT_INSTRUCTION_ACCESS_ERROR*ENTRY_SIZE
.global instruction_access_error_tl0
instruction_access_error_tl0:
        PREEMPTIBLE_HANDLER instruction_access_error

/* TT = 0x10, TL = 0, illegal_instruction */
.org trap_table + TT_ILLEGAL_INSTRUCTION*ENTRY_SIZE
.global illegal_instruction_tl0
illegal_instruction_tl0:
        PREEMPTIBLE_HANDLER illegal_instruction

/* TT = 0x11, TL = 0, privileged_opcode */
.org trap_table + TT_PRIVILEGED_OPCODE*ENTRY_SIZE
.global privileged_opcode_tl0
privileged_opcode_tl0:
        PREEMPTIBLE_HANDLER privileged_opcode

/* TT = 0x12, TL = 0, unimplemented_LDD */
.org trap_table + TT_UNIMPLEMENTED_LDD*ENTRY_SIZE
.global unimplemented_LDD_tl0
unimplemented_LDD_tl0:
        PREEMPTIBLE_HANDLER unimplemented_LDD

/* TT = 0x13, TL = 0, unimplemented_STD */
.org trap_table + TT_UNIMPLEMENTED_STD*ENTRY_SIZE
.global unimplemented_STD_tl0
unimplemented_STD_tl0:
        PREEMPTIBLE_HANDLER unimplemented_STD

/* TT = 0x20, TL = 0, fb_disabled handler */
.org trap_table + TT_FP_DISABLED*ENTRY_SIZE
.global fb_disabled_tl0
fp_disabled_tl0:
        PREEMPTIBLE_HANDLER fp_disabled

/* TT = 0x21, TL = 0, fb_exception_ieee_754 handler */
.org trap_table + TT_FP_EXCEPTION_IEEE_754*ENTRY_SIZE
.global fb_exception_ieee_754_tl0
fp_exception_ieee_754_tl0:
        PREEMPTIBLE_HANDLER fp_exception_ieee_754

/* TT = 0x22, TL = 0, fb_exception_other handler */
.org trap_table + TT_FP_EXCEPTION_OTHER*ENTRY_SIZE
.global fb_exception_other_tl0
fp_exception_other_tl0:
        PREEMPTIBLE_HANDLER fp_exception_other

/* TT = 0x23, TL = 0, tag_overflow */
.org trap_table + TT_TAG_OVERFLOW*ENTRY_SIZE
.global tag_overflow_tl0
tag_overflow_tl0:
        PREEMPTIBLE_HANDLER tag_overflow

/* TT = 0x24, TL = 0, clean_window handler */
.org trap_table + TT_CLEAN_WINDOW*ENTRY_SIZE
.global clean_window_tl0
clean_window_tl0:
        CLEAN_WINDOW_HANDLER

/* TT = 0x28, TL = 0, division_by_zero */
.org trap_table + TT_DIVISION_BY_ZERO*ENTRY_SIZE
.global division_by_zero_tl0
division_by_zero_tl0:
        PREEMPTIBLE_HANDLER division_by_zero

/* TT = 0x30, TL = 0, data_access_exception */
.org trap_table + TT_DATA_ACCESS_EXCEPTION*ENTRY_SIZE
.global data_access_exception_tl0
data_access_exception_tl0:
        wrpr %g0, PSTATE_AG_BIT | PSTATE_PRIV_BIT, %pstate
        PREEMPTIBLE_HANDLER data_access_exception

/* TT = 0x32, TL = 0, data_access_error */
.org trap_table + TT_DATA_ACCESS_ERROR*ENTRY_SIZE
.global data_access_error_tl0
data_access_error_tl0:
        PREEMPTIBLE_HANDLER 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_tl0
mem_address_not_aligned_tl0:
        PREEMPTIBLE_HANDLER mem_address_not_aligned

/* TT = 0x35, TL = 0, LDDF_mem_address_not_aligned */
.org trap_table + TT_LDDF_MEM_ADDRESS_NOT_ALIGNED*ENTRY_SIZE
.global LDDF_mem_address_not_aligned_tl0
LDDF_mem_address_not_aligned_tl0:
        PREEMPTIBLE_HANDLER LDDF_mem_address_not_aligned

/* TT = 0x36, TL = 0, STDF_mem_address_not_aligned */
.org trap_table + TT_STDF_MEM_ADDRESS_NOT_ALIGNED*ENTRY_SIZE
.global STDF_mem_address_not_aligned_tl0
STDF_mem_address_not_aligned_tl0:
        PREEMPTIBLE_HANDLER STDF_mem_address_not_aligned

/* TT = 0x37, TL = 0, privileged_action */
.org trap_table + TT_PRIVILEGED_ACTION*ENTRY_SIZE
.global privileged_action_tl0
privileged_action_tl0:
        PREEMPTIBLE_HANDLER privileged_action

/* TT = 0x38, TL = 0, LDQF_mem_address_not_aligned */
.org trap_table + TT_LDQF_MEM_ADDRESS_NOT_ALIGNED*ENTRY_SIZE
.global LDQF_mem_address_not_aligned_tl0
LDQF_mem_address_not_aligned_tl0:
        PREEMPTIBLE_HANDLER LDQF_mem_address_not_aligned

/* TT = 0x39, TL = 0, STQF_mem_address_not_aligned */
.org trap_table + TT_STQF_MEM_ADDRESS_NOT_ALIGNED*ENTRY_SIZE
.global STQF_mem_address_not_aligned_tl0
STQF_mem_address_not_aligned_tl0:
        PREEMPTIBLE_HANDLER STQF_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_tl0
interrupt_level_1_handler_tl0:
        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_tl0
interrupt_level_2_handler_tl0:
        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_tl0
interrupt_level_3_handler_tl0:
        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_tl0
interrupt_level_4_handler_tl0:
        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_tl0
interrupt_level_5_handler_tl0:
        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_tl0
interrupt_level_6_handler_tl0:
        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_tl0
interrupt_level_7_handler_tl0:
        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_tl0
interrupt_level_8_handler_tl0:
        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_tl0
interrupt_level_9_handler_tl0:
        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_tl0
interrupt_level_10_handler_tl0:
        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_tl0
interrupt_level_11_handler_tl0:
        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_tl0
interrupt_level_12_handler_tl0:
        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_tl0
interrupt_level_13_handler_tl0:
        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_tl0
interrupt_level_14_handler_tl0:
        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_tl0
interrupt_level_15_handler_tl0:
        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_tl0
interrupt_vector_trap_handler_tl0:
        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_tl0
fast_instruction_access_mmu_miss_handler_tl0:
        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_tl0
fast_data_access_mmu_miss_handler_tl0:
        FAST_DATA_ACCESS_MMU_MISS_HANDLER 0

/* TT = 0x6c, TL = 0, fast_data_access_protection */
.org trap_table + TT_FAST_DATA_ACCESS_PROTECTION*ENTRY_SIZE
.global fast_data_access_protection_handler_tl0
fast_data_access_protection_handler_tl0:
        FAST_DATA_ACCESS_PROTECTION_HANDLER 0

/* TT = 0x80, TL = 0, spill_0_normal handler */
.org trap_table + TT_SPILL_0_NORMAL*ENTRY_SIZE
.global spill_0_normal_tl0
spill_0_normal_tl0:
        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_tl0
spill_1_normal_tl0:
        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_tl0
spill_2_normal_tl0:
        SPILL_TO_USPACE_WINDOW_BUFFER

/* TT = 0xa0, TL = 0, spill_0_other handler */
.org trap_table + TT_SPILL_0_OTHER*ENTRY_SIZE
.global spill_0_other_tl0
spill_0_other_tl0:
        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_tl0
fill_0_normal_tl0:
        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_tl0
fill_1_normal_tl0:
        FILL_NORMAL_HANDLER_USERSPACE

/* TT = 0x100 - 0x17f, TL = 0, trap_instruction_0 - trap_instruction_7f */
.irp cur, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,\
    20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,\
    39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,\
    58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76,\
    77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,\
    96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,\
    112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126,\
    127
.org trap_table + (TT_TRAP_INSTRUCTION_0+\cur)*ENTRY_SIZE
.global trap_instruction_\cur\()_tl0
trap_instruction_\cur\()_tl0:
        ba trap_instruction_handler
        mov \cur, %g2
.endr

/*
 * 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_tl1
instruction_access_exception_tl1:
        wrpr %g0, 1, %tl
        wrpr %g0, PSTATE_AG_BIT | PSTATE_PRIV_BIT, %pstate
        PREEMPTIBLE_HANDLER instruction_access_exception

/* TT = 0x0a, TL > 0, instruction_access_error */
.org trap_table + (TT_INSTRUCTION_ACCESS_ERROR+512)*ENTRY_SIZE
.global instruction_access_error_tl1
instruction_access_error_tl1:
        wrpr %g0, 1, %tl
        PREEMPTIBLE_HANDLER instruction_access_error

/* TT = 0x10, TL > 0, illegal_instruction */
.org trap_table + (TT_ILLEGAL_INSTRUCTION+512)*ENTRY_SIZE
.global illegal_instruction_tl1
illegal_instruction_tl1:
        wrpr %g0, 1, %tl
        PREEMPTIBLE_HANDLER illegal_instruction

/* TT = 0x24, TL > 0, clean_window handler */
.org trap_table + (TT_CLEAN_WINDOW+512)*ENTRY_SIZE
.global clean_window_tl1
clean_window_tl1:
        CLEAN_WINDOW_HANDLER

/* TT = 0x28, TL > 0, division_by_zero */
.org trap_table + (TT_DIVISION_BY_ZERO+512)*ENTRY_SIZE
.global division_by_zero_tl1
division_by_zero_tl1:
        wrpr %g0, 1, %tl
        PREEMPTIBLE_HANDLER division_by_zero

/* TT = 0x30, TL > 0, data_access_exception */
.org trap_table + (TT_DATA_ACCESS_EXCEPTION+512)*ENTRY_SIZE
.global data_access_exception_tl1
data_access_exception_tl1:
        wrpr %g0, 1, %tl
        wrpr %g0, PSTATE_AG_BIT | PSTATE_PRIV_BIT, %pstate
        PREEMPTIBLE_HANDLER data_access_exception

/* TT = 0x32, TL > 0, data_access_error */
.org trap_table + (TT_DATA_ACCESS_ERROR+512)*ENTRY_SIZE
.global data_access_error_tl1
data_access_error_tl1:
        wrpr %g0, 1, %tl
        PREEMPTIBLE_HANDLER 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_tl1
mem_address_not_aligned_tl1:
        wrpr %g0, 1, %tl
        PREEMPTIBLE_HANDLER mem_address_not_aligned

/* 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_tl1
fast_data_access_mmu_miss_handler_tl1:
        FAST_DATA_ACCESS_MMU_MISS_HANDLER 1

/* 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_tl1
fast_data_access_protection_handler_tl1:
        FAST_DATA_ACCESS_PROTECTION_HANDLER 1

/* TT = 0x80, TL > 0, spill_0_normal handler */
.org trap_table + (TT_SPILL_0_NORMAL+512)*ENTRY_SIZE
.global spill_0_normal_tl1
spill_0_normal_tl1:
        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_tl1
spill_2_normal_tl1:
        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_tl1
spill_0_other_tl1:
        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_tl1
fill_0_normal_tl1:
        FILL_NORMAL_HANDLER_KERNEL

.align TABLE_SIZE


#define NOT(x)  ((x) == 0)

/* 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.
 *
 * The kernel is designed to work on trap levels 0 - 4. For instance, the
 * following can happen:
 * TL0: kernel thread runs (CANSAVE=0, kernel stack not in DTLB)
 * TL1: preemptible trap handler started after a tick interrupt
 * TL2: preemptible trap handler did SAVE
 * TL3: spill handler touched the kernel stack  
 * TL4: hardware or software failure
 *
 * Input registers:
 *      %g1             Address of function to call if this is not a syscall.
 *      %g2             First 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.
 */
.macro PREEMPTIBLE_HANDLER_TEMPLATE is_syscall
        /*
         * ASSERT(%tl == 1)
         */
        rdpr %tl, %g3
        cmp %g3, 1
        be 1f
        nop
0:      ba 0b                                   ! this is for debugging, if we ever get here
        nop                                     ! it will be easy to find

1:
.if NOT(\is_syscall)
        rdpr %tstate, %g3
        
        /*
         * One of the ways this handler can be invoked is after a nested MMU trap from
         * either spill_1_normal or fill_1_normal traps. Both of these traps manipulate
         * the CWP register. We deal with the situation by simulating the MMU trap
         * on TL=1 and restart the respective SAVE or RESTORE instruction once the MMU
         * trap is resolved. However, because we are in the wrong window from the
         * perspective of the MMU trap, we need to synchronize CWP with CWP from TL=0.
         */ 
        and %g3, TSTATE_CWP_MASK, %g4
        wrpr %g4, 0, %cwp                       ! resynchronize CWP

        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
        
.endif
        /*
         * Normal window spills will go to the userspace window buffer.
         */
        wrpr %g0, WSTATE_OTHER(0) | WSTATE_NORMAL(2), %wstate

        wrpr %g0, NWINDOWS - 1, %cleanwin       ! prevent unnecessary clean_window exceptions

        /*
         * 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

.if \is_syscall
        /*
         * Copy arguments for the syscall to the new window.
         */
        mov %i0, %o0
        mov %i1, %o1
        mov %i2, %o2
        mov %i3, %o3
        mov %i4, %o4
        mov %i5, %o5
.endif

        /*
         * Mark the CANRESTORE windows as OTHER windows.
         */
        rdpr %canrestore, %l0
        wrpr %l0, %otherwin
        wrpr %g0, %canrestore

        /*
         * Switch to primary context 0.
         */
        mov VA_PRIMARY_CONTEXT_REG, %l0
        stxa %g0, [%l0] ASI_DMMU
        rd %pc, %l0
        flush %l0

.if NOT(\is_syscall)
        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:
.endif
        /*
         * 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
.if NOT(\is_syscall)
        mov %g2, %o0
.else
        ! store the syscall number on the stack as 7th argument
        stx %g2, [%sp + STACK_WINDOW_SAVE_AREA_SIZE + STACK_BIAS + STACK_ARG6] 
.endif

        /*
         * Save TSTATE, TPC and TNPC aside.
         */
        rdpr %tstate, %g1
        rdpr %tpc, %g2
        rdpr %tnpc, %g3
        rd %y, %g4

        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]

        /*
         * Save the Y register.
         * This register is deprecated according to SPARC V9 specification
         * and is only present for backward compatibility with previous
         * versions of the SPARC architecture.
         * Surprisingly, gcc makes use of this register without a notice.
         */
        stx %g4, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_Y]
        
        wrpr %g0, 0, %tl
        wrpr %g0, PSTATE_PRIV_BIT | PSTATE_PEF_BIT, %pstate
        SAVE_GLOBALS
        
.if NOT(\is_syscall)
        /*
         * 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
.else
        /*
         * Call the higher-level syscall handler.
         */
        call syscall_handler
        nop
        mov %o0, %i0                            ! copy the value returned by the syscall
.endif

        RESTORE_GLOBALS
        rdpr %pstate, %l1                       ! we must preserve the PEF bit
        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

        /*
         * Copy PSTATE.PEF to the in-register copy of TSTATE.
         */
        and %l1, PSTATE_PEF_BIT, %l1
        sllx %l1, TSTATE_PSTATE_SHIFT, %l1
        sethi %hi(TSTATE_PEF_BIT), %g4
        andn %g1, %g4, %g1
        or %g1, %l1, %g1

        /*
         * Restore TSTATE, TPC and TNPC from saved copies.
         */
        wrpr %g1, 0, %tstate
        wrpr %g2, 0, %tpc
        wrpr %g3, 0, %tnpc

        /*
         * Restore Y.
         */
        ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_Y], %g4
        wr %g4, %y

        /*
         * If OTHERWIN is zero, then all the userspace windows have been
         * spilled to kernel memory (i.e. register window buffer). Moreover,
         * if the scheduler was called in the meantime, all valid windows
         * belonging to other threads were spilled by context_restore().
         * 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, NWINDOWS - 1, %l0      ! %l0 mod NWINDOWS
        rdpr %cwp, %l1
        cmp %l0, %l1
        bz 0f                           ! CWP is ok
        nop

        /*
         * Fix CWP.
         * In order to recapitulate, 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.
         */
        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 after the SAVE
         * at the beginning of this function.
         */
0:
.if NOT(\is_syscall)
        rdpr %tstate, %g1
        andcc %g1, TSTATE_PRIV_BIT, %g0         ! if we are not returning to userspace...,
        bnz 1f                                  ! ...skip restoring userspace windows
        nop
.endif

        /*
         * 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
        rd %pc, %g1
        flush %g1
        
        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, NWINDOWS - 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
        set PAGE_SIZE - 1, %g5
0:      andcc %g7, %g5, %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, NWINDOWS - 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, NWINDOWS - 2
        bg 2f                                   ! fix the CANRESTORE=NWINDOWS-1 anomaly
        mov NWINDOWS - 2, %g1                   ! use dealy slot for both cases
        sub %g1, %g2, %g1
        
        wrpr %g0, 0, %otherwin
        wrpr %g1, 0, %cansave                   ! NWINDOWS - 2 - CANRESTORE
        wrpr %g2, 0, %canrestore                ! OTHERWIN + windows in the buffer
        wrpr %g2, 0, %cleanwin                  ! avoid information leak

1:
        restore

.if \is_syscall
        done
.else
        retry
.endif

        /*
         * 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 NWINDOWS - 1 register windows.
         * However, CANRESTORE can be only NWINDOW - 2 at most.
         *
         * The solution is to manually switch to (CWP - 1) mod NWINDOWS
         * and set the window state registers so that:
         *
         *      CANRESTORE      = NWINDOWS - 2
         *      CLEANWIN        = NWINDOWS - 2
         *      CANSAVE         = 0
         *      OTHERWIN        = 0
         *
         * The RESTORE instruction 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, NWINDOWS - 1, %g1
        wrpr %g1, 0, %cwp                       ! CWP--
        
.if \is_syscall
        done
.else
        retry
.endif

.endm

.global preemptible_handler
preemptible_handler:
        PREEMPTIBLE_HANDLER_TEMPLATE 0

.global trap_instruction_handler
trap_instruction_handler:
        PREEMPTIBLE_HANDLER_TEMPLATE 1