WebSVN – HelenOS – Diff – /trunk/kernel/arch/sparc64/src/trap/trap_table.S


#
# 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
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# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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/**
 * 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
 
Subversion Repositories HelenOS

(root)/trunk/kernel/arch/sparc64/src/trap/trap_table.S – Rev 1860 → 1861
