[linux-2.6-block.git] / arch / sparc / kernel / wuf.S

/*
 * wuf.S: Window underflow trap handler for the Sparc.
 *
 * Copyright (C) 1995 David S. Miller
 */

#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>

/* Just like the overflow handler we define macros for registers
 * with fixed meanings in this routine.
 */
#define t_psr       l0
#define t_pc        l1
#define t_npc       l2
#define t_wim       l3
/* Don't touch the above registers or else you die horribly... */

/* Now macros for the available scratch registers in this routine. */
#define twin_tmp1    l4
#define twin_tmp2    l5

#define curptr       g6

	.text
	.align	4

	/* The trap entry point has executed the following:
	 *
	 * rd    %psr, %l0
	 * rd    %wim, %l3
	 * b     fill_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.
	 */

	/* To get an idea of what has just happened to cause this
	 * trap take a look at this diagram:
	 *
	 *      1  2  3  4     <--  Window number
	 *      ----------
	 *      T  O  W  I     <--  Symbolic name
	 *
	 *      O == the window that execution was in when
	 *           the restore was attempted
	 *
	 *      T == the trap itself has save'd us into this
	 *           window
	 *
	 *      W == this window is the one which is now invalid
	 *           and must be made valid plus loaded from the
	 *           stack
	 *
	 *      I == this window will be the invalid one when we
	 *           are done and return from trap if successful
	 */

	/* BEGINNING OF PATCH INSTRUCTIONS */

	/* On 7-window Sparc the boot code patches fnwin_patch1
	 * with the following instruction.
	 */
	.globl	fnwin_patch1_7win, fnwin_patch2_7win
fnwin_patch1_7win:	srl	%t_wim, 6, %twin_tmp2
fnwin_patch2_7win:	and	%twin_tmp1, 0x7f, %twin_tmp1
	/* END OF PATCH INSTRUCTIONS */

	.globl	fill_window_entry, fnwin_patch1, fnwin_patch2
fill_window_entry:
	/* LOCATION: Window 'T' */

	/* Compute what the new %wim is going to be if we retrieve
	 * the proper window off of the stack.
	 */
		sll	%t_wim, 1, %twin_tmp1
fnwin_patch1:	srl	%t_wim, 7, %twin_tmp2
		or	%twin_tmp1, %twin_tmp2, %twin_tmp1
fnwin_patch2:	and	%twin_tmp1, 0xff, %twin_tmp1

	wr	%twin_tmp1, 0x0, %wim	/* Make window 'I' invalid */

	andcc	%t_psr, PSR_PS, %g0
	be	fwin_from_user
	 restore	%g0, %g0, %g0		/* Restore to window 'O' */

	/* Trapped from kernel, we trust that the kernel does not
	 * 'over restore' sorta speak and just grab the window
	 * from the stack and return.  Easy enough.
	 */
fwin_from_kernel:
	/* LOCATION: Window 'O' */

	restore %g0, %g0, %g0

	/* LOCATION: Window 'W' */

	LOAD_WINDOW(sp)	                /* Load it up */

	/* Spin the wheel... */
	save	%g0, %g0, %g0
	save	%g0, %g0, %g0
	/* I'd like to buy a vowel please... */

	/* LOCATION: Window 'T' */

	/* Now preserve the condition codes in %psr, pause, and
	 * return from trap.  This is the simplest case of all.
	 */
	wr	%t_psr, 0x0, %psr
	WRITE_PAUSE

	jmp	%t_pc
	rett	%t_npc

fwin_from_user:
	/* LOCATION: Window 'O' */

	restore	%g0, %g0, %g0		/* Restore to window 'W' */

	/* LOCATION: Window 'W' */

	/* Branch to the stack validation routine */
	b	srmmu_fwin_stackchk
	 andcc	%sp, 0x7, %g0

#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ)

fwin_user_stack_is_bolixed:
	/* LOCATION: Window 'W' */

	/* Place a pt_regs frame on the kernel stack, save back
	 * to the trap window and call c-code to deal with this.
	 */
	LOAD_CURRENT(l4, l5)

	sethi	%hi(STACK_OFFSET), %l5
	or	%l5, %lo(STACK_OFFSET), %l5
	add	%l4, %l5, %l5

	/* Store globals into pt_regs frame. */
	STORE_PT_GLOBALS(l5)
	STORE_PT_YREG(l5, g3)

	/* Save current in a global while we change windows. */
	mov	%l4, %curptr

	save	%g0, %g0, %g0

	/* LOCATION: Window 'O' */

	rd	%psr, %g3		/* Read %psr in live user window */
	mov	%fp, %g4		/* Save bogus frame pointer. */

	save	%g0, %g0, %g0

	/* LOCATION: Window 'T' */

	sethi	%hi(STACK_OFFSET), %l5
	or	%l5, %lo(STACK_OFFSET), %l5
	add	%curptr, %l5, %sp

	/* Build rest of pt_regs. */
	STORE_PT_INS(sp)
	STORE_PT_PRIV(sp, t_psr, t_pc, t_npc)

	/* re-set trap time %wim value */
	wr	%t_wim, 0x0, %wim

	/* Fix users window mask and buffer save count. */
	mov	0x1, %g5
	sll	%g5, %g3, %g5
	st	%g5, [%curptr + TI_UWINMASK]		! one live user window still
	st	%g0, [%curptr + TI_W_SAVED]		! no windows in the buffer

	wr	%t_psr, PSR_ET, %psr			! enable traps
	nop
	call	window_underflow_fault
	 mov	%g4, %o0

	b	ret_trap_entry
	 clr	%l6

fwin_user_stack_is_ok:
	/* LOCATION: Window 'W' */

	/* The users stack area is kosher and mapped, load the
	 * window and fall through to the finish up routine.
	 */
	LOAD_WINDOW(sp)

	/* Round and round she goes... */
	save	%g0, %g0, %g0		/* Save to window 'O' */
	save	%g0, %g0, %g0		/* Save to window 'T' */
	/* Where she'll trap nobody knows... */

	/* LOCATION: Window 'T' */

fwin_user_finish_up:
	/* LOCATION: Window 'T' */

	wr	%t_psr, 0x0, %psr
	WRITE_PAUSE	

	jmp	%t_pc
	rett	%t_npc

	/* Here come the architecture specific checks for stack.
	 * mappings.  Note that unlike the window overflow handler
	 * we only need to check whether the user can read from
	 * the appropriate addresses.  Also note that we are in
	 * an invalid window which will be loaded, and this means
	 * that until we actually load the window up we are free
	 * to use any of the local registers contained within.
	 *
	 * On success these routine branch to fwin_user_stack_is_ok
	 * if the area at %sp is user readable and the window still
	 * needs to be loaded, else fwin_user_finish_up if the
	 * routine has done the loading itself.  On failure (bogus
	 * user stack) the routine shall branch to the label called
	 * fwin_user_stack_is_bolixed.
	 *
	 * Contrary to the arch-specific window overflow stack
	 * check routines in wof.S, these routines are free to use
	 * any of the local registers they want to as this window
	 * does not belong to anyone at this point, however the
	 * outs and ins are still verboten as they are part of
	 * 'someone elses' window possibly.
	 */

	.globl	srmmu_fwin_stackchk
srmmu_fwin_stackchk:
	/* LOCATION: Window 'W' */

	/* Caller did 'andcc %sp, 0x7, %g0' */
	bne	fwin_user_stack_is_bolixed
	 sethi   %hi(PAGE_OFFSET), %l5

	/* Check if the users stack is in kernel vma, then our
	 * trial and error technique below would succeed for
	 * the 'wrong' reason.
	 */
	mov	AC_M_SFSR, %l4
	cmp	%l5, %sp
	bleu	fwin_user_stack_is_bolixed
LEON_PI( lda	[%l4] ASI_LEON_MMUREGS, %g0)	! clear fault status
SUN_PI_( lda	[%l4] ASI_M_MMUREGS, %g0)	! clear fault status

	/* The technique is, turn off faults on this processor,
	 * just let the load rip, then check the sfsr to see if
	 * a fault did occur.  Then we turn on fault traps again
	 * and branch conditionally based upon what happened.
	 */
LEON_PI(lda	[%g0] ASI_LEON_MMUREGS, %l5)	! read mmu-ctrl reg
SUN_PI_(lda	[%g0] ASI_M_MMUREGS, %l5)	! read mmu-ctrl reg
	or	%l5, 0x2, %l5			! turn on no-fault bit
LEON_PI(sta	%l5, [%g0] ASI_LEON_MMUREGS)	! store it
SUN_PI_(sta	%l5, [%g0] ASI_M_MMUREGS)	! store it

	/* Cross fingers and go for it. */
	LOAD_WINDOW(sp)

	/* A penny 'saved'... */
	save	%g0, %g0, %g0
	save	%g0, %g0, %g0
	/* Is a BADTRAP earned... */

	/* LOCATION: Window 'T' */

LEON_PI(lda	[%g0] ASI_LEON_MMUREGS, %twin_tmp1)	! load mmu-ctrl again
SUN_PI_(lda	[%g0] ASI_M_MMUREGS, %twin_tmp1)	! load mmu-ctrl again
	andn	%twin_tmp1, 0x2, %twin_tmp1		! clear no-fault bit
LEON_PI(sta	%twin_tmp1, [%g0] ASI_LEON_MMUREGS)	! store it
SUN_PI_(sta	%twin_tmp1, [%g0] ASI_M_MMUREGS)	! store it

	mov	AC_M_SFAR, %twin_tmp2
LEON_PI(lda	[%twin_tmp2] ASI_LEON_MMUREGS, %g0)	! read fault address
SUN_PI_(lda	[%twin_tmp2] ASI_M_MMUREGS, %g0)	! read fault address

	mov	AC_M_SFSR, %twin_tmp2
LEON_PI(lda	[%twin_tmp2] ASI_LEON_MMUREGS, %twin_tmp2) ! read fault status
SUN_PI_(lda	[%twin_tmp2] ASI_M_MMUREGS, %twin_tmp2)	   ! read fault status
	andcc	%twin_tmp2, 0x2, %g0			   ! did fault occur?

	bne	1f					   ! yep, cleanup
	 nop

	wr	%t_psr, 0x0, %psr
	nop
	b	fwin_user_finish_up + 0x4
	 nop

	/* Did I ever tell you about my window lobotomy?
	 * anyways... fwin_user_stack_is_bolixed expects
	 * to be in window 'W' so make it happy or else
	 * we watchdog badly.
	 */
1:
	restore	%g0, %g0, %g0
	b	fwin_user_stack_is_bolixed	! oh well
	 restore	%g0, %g0, %g0
Commit	Line	Data
88278ca2	1	/*
1da177e4 LT	2	* wuf.S: Window underflow trap handler for the Sparc.
	3	*
	4	* Copyright (C) 1995 David S. Miller
	5	*/
	6
	7	#include <asm/contregs.h>
	8	#include <asm/page.h>
	9	#include <asm/ptrace.h>
	10	#include <asm/psr.h>
	11	#include <asm/smp.h>
	12	#include <asm/asi.h>
	13	#include <asm/winmacro.h>
	14	#include <asm/asmmacro.h>
	15	#include <asm/thread_info.h>
	16
	17	/* Just like the overflow handler we define macros for registers
	18	* with fixed meanings in this routine.
	19	*/
	20	#define t_psr l0
	21	#define t_pc l1
	22	#define t_npc l2
	23	#define t_wim l3
	24	/* Don't touch the above registers or else you die horribly... */
	25
	26	/* Now macros for the available scratch registers in this routine. */
	27	#define twin_tmp1 l4
	28	#define twin_tmp2 l5
	29
	30	#define curptr g6
	31
	32	.text
	33	.align 4
	34
	35	/* The trap entry point has executed the following:
	36	*
	37	* rd %psr, %l0
	38	* rd %wim, %l3
	39	* b fill_window_entry
	40	* andcc %l0, PSR_PS, %g0
	41	*/
	42
	43	/* Datum current_thread_info->uwinmask contains at all times a bitmask
	44	* where if any user windows are active, at least one bit will
	45	* be set in to mask. If no user windows are active, the bitmask
	46	* will be all zeroes.
	47	*/
	48
	49	/* To get an idea of what has just happened to cause this
	50	* trap take a look at this diagram:
	51	*
	52	* 1 2 3 4 <-- Window number
	53	* ----------
	54	* T O W I <-- Symbolic name
	55	*
	56	* O == the window that execution was in when
	57	* the restore was attempted
	58	*
	59	* T == the trap itself has save'd us into this
	60	* window
	61	*
	62	* W == this window is the one which is now invalid
	63	* and must be made valid plus loaded from the
	64	* stack
	65	*
66	* I == this window will be the invalid one when we
67	* are done and return from trap if successful
68	*/
69
70	/* BEGINNING OF PATCH INSTRUCTIONS */
71
72	/* On 7-window Sparc the boot code patches fnwin_patch1
73	* with the following instruction.
74	*/
75	.globl fnwin_patch1_7win, fnwin_patch2_7win
76	fnwin_patch1_7win: srl %t_wim, 6, %twin_tmp2
77	fnwin_patch2_7win: and %twin_tmp1, 0x7f, %twin_tmp1
78	/* END OF PATCH INSTRUCTIONS */
79
80	.globl fill_window_entry, fnwin_patch1, fnwin_patch2
81	fill_window_entry:
82	/* LOCATION: Window 'T' */
83
84	/* Compute what the new %wim is going to be if we retrieve
85	* the proper window off of the stack.
86	*/
87	sll %t_wim, 1, %twin_tmp1
88	fnwin_patch1: srl %t_wim, 7, %twin_tmp2
89	or %twin_tmp1, %twin_tmp2, %twin_tmp1
90	fnwin_patch2: and %twin_tmp1, 0xff, %twin_tmp1
91
92	wr %twin_tmp1, 0x0, %wim /* Make window 'I' invalid */
93
94	andcc %t_psr, PSR_PS, %g0
95	be fwin_from_user
96	restore %g0, %g0, %g0 /* Restore to window 'O' */
97
98	/* Trapped from kernel, we trust that the kernel does not
99	* 'over restore' sorta speak and just grab the window
100	* from the stack and return. Easy enough.
101	*/
102	fwin_from_kernel:
103	/* LOCATION: Window 'O' */
104
105	restore %g0, %g0, %g0
106
107	/* LOCATION: Window 'W' */
108
109	LOAD_WINDOW(sp) /* Load it up */
110
111	/* Spin the wheel... */
112	save %g0, %g0, %g0
113	save %g0, %g0, %g0
114	/* I'd like to buy a vowel please... */
115
116	/* LOCATION: Window 'T' */
117
118	/* Now preserve the condition codes in %psr, pause, and
119	* return from trap. This is the simplest case of all.
120	*/
121	wr %t_psr, 0x0, %psr
122	WRITE_PAUSE
123
124	jmp %t_pc
125	rett %t_npc
126
127	fwin_from_user:
128	/* LOCATION: Window 'O' */
129
130	restore %g0, %g0, %g0 /* Restore to window 'W' */
131
132	/* LOCATION: Window 'W' */
133
28de2f73 SR	134	/* Branch to the stack validation routine */
	135	b srmmu_fwin_stackchk
	136	andcc %sp, 0x7, %g0
1da177e4 LT	137
	138	#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ)
	139
	140	fwin_user_stack_is_bolixed:
	141	/* LOCATION: Window 'W' */
	142
	143	/* Place a pt_regs frame on the kernel stack, save back
	144	* to the trap window and call c-code to deal with this.
	145	*/
	146	LOAD_CURRENT(l4, l5)
	147
	148	sethi %hi(STACK_OFFSET), %l5
	149	or %l5, %lo(STACK_OFFSET), %l5
	150	add %l4, %l5, %l5
	151
	152	/* Store globals into pt_regs frame. */
	153	STORE_PT_GLOBALS(l5)
	154	STORE_PT_YREG(l5, g3)
	155
	156	/* Save current in a global while we change windows. */
	157	mov %l4, %curptr
	158
	159	save %g0, %g0, %g0
	160
	161	/* LOCATION: Window 'O' */
	162
	163	rd %psr, %g3 /* Read %psr in live user window */
	164	mov %fp, %g4 /* Save bogus frame pointer. */
	165
	166	save %g0, %g0, %g0
	167
	168	/* LOCATION: Window 'T' */
	169
	170	sethi %hi(STACK_OFFSET), %l5
	171	or %l5, %lo(STACK_OFFSET), %l5
	172	add %curptr, %l5, %sp
	173
	174	/* Build rest of pt_regs. */
	175	STORE_PT_INS(sp)
	176	STORE_PT_PRIV(sp, t_psr, t_pc, t_npc)
	177
	178	/* re-set trap time %wim value */
	179	wr %t_wim, 0x0, %wim
	180
	181	/* Fix users window mask and buffer save count. */
	182	mov 0x1, %g5
	183	sll %g5, %g3, %g5
	184	st %g5, [%curptr + TI_UWINMASK] ! one live user window still
	185	st %g0, [%curptr + TI_W_SAVED] ! no windows in the buffer
	186
	187	wr %t_psr, PSR_ET, %psr ! enable traps
	188	nop
	189	call window_underflow_fault
	190	mov %g4, %o0
	191
	192	b ret_trap_entry
	193	clr %l6
	194
	195	fwin_user_stack_is_ok:
	196	/* LOCATION: Window 'W' */
	197
	198	/* The users stack area is kosher and mapped, load the
	199	* window and fall through to the finish up routine.
	200	*/
201	LOAD_WINDOW(sp)
202
203	/* Round and round she goes... */
204	save %g0, %g0, %g0 /* Save to window 'O' */
205	save %g0, %g0, %g0 /* Save to window 'T' */
206	/* Where she'll trap nobody knows... */
207
208	/* LOCATION: Window 'T' */
209
210	fwin_user_finish_up:
211	/* LOCATION: Window 'T' */
212
213	wr %t_psr, 0x0, %psr
214	WRITE_PAUSE
215
216	jmp %t_pc
217	rett %t_npc
218
219	/* Here come the architecture specific checks for stack.
220	* mappings. Note that unlike the window overflow handler
221	* we only need to check whether the user can read from
222	* the appropriate addresses. Also note that we are in
223	* an invalid window which will be loaded, and this means
224	* that until we actually load the window up we are free
225	* to use any of the local registers contained within.
226	*
227	* On success these routine branch to fwin_user_stack_is_ok
228	* if the area at %sp is user readable and the window still
229	* needs to be loaded, else fwin_user_finish_up if the
230	* routine has done the loading itself. On failure (bogus
231	* user stack) the routine shall branch to the label called
232	* fwin_user_stack_is_bolixed.
233	*
234	* Contrary to the arch-specific window overflow stack
235	* check routines in wof.S, these routines are free to use
236	* any of the local registers they want to as this window
237	* does not belong to anyone at this point, however the
238	* outs and ins are still verboten as they are part of
239	* 'someone elses' window possibly.
240	*/
241
1da177e4 LT	242	.globl srmmu_fwin_stackchk
	243	srmmu_fwin_stackchk:
	244	/* LOCATION: Window 'W' */
	245
	246	/* Caller did 'andcc %sp, 0x7, %g0' */
	247	bne fwin_user_stack_is_bolixed
	248	sethi %hi(PAGE_OFFSET), %l5
	249
	250	/* Check if the users stack is in kernel vma, then our
	251	* trial and error technique below would succeed for
	252	* the 'wrong' reason.
	253	*/
	254	mov AC_M_SFSR, %l4
	255	cmp %l5, %sp
	256	bleu fwin_user_stack_is_bolixed
1ec8cf62 SR	257	LEON_PI( lda [%l4] ASI_LEON_MMUREGS, %g0) ! clear fault status
1ec8cf62 SR	258	SUN_PI_( lda [%l4] ASI_M_MMUREGS, %g0) ! clear fault status
1da177e4 LT	259
	260	/* The technique is, turn off faults on this processor,
	261	* just let the load rip, then check the sfsr to see if
	262	* a fault did occur. Then we turn on fault traps again
	263	* and branch conditionally based upon what happened.
	264	*/
1ec8cf62 SR	265	LEON_PI(lda [%g0] ASI_LEON_MMUREGS, %l5) ! read mmu-ctrl reg
1ec8cf62 SR	266	SUN_PI_(lda [%g0] ASI_M_MMUREGS, %l5) ! read mmu-ctrl reg
1da177e4	267	or %l5, 0x2, %l5 ! turn on no-fault bit
1ec8cf62 SR	268	LEON_PI(sta %l5, [%g0] ASI_LEON_MMUREGS) ! store it
1ec8cf62 SR	269	SUN_PI_(sta %l5, [%g0] ASI_M_MMUREGS) ! store it
1da177e4 LT	270
	271	/* Cross fingers and go for it. */
	272	LOAD_WINDOW(sp)
	273
	274	/* A penny 'saved'... */
	275	save %g0, %g0, %g0
	276	save %g0, %g0, %g0
	277	/* Is a BADTRAP earned... */
	278
	279	/* LOCATION: Window 'T' */
	280
1ec8cf62 SR	281	LEON_PI(lda [%g0] ASI_LEON_MMUREGS, %twin_tmp1) ! load mmu-ctrl again
	282	SUN_PI_(lda [%g0] ASI_M_MMUREGS, %twin_tmp1) ! load mmu-ctrl again
	283	andn %twin_tmp1, 0x2, %twin_tmp1 ! clear no-fault bit
	284	LEON_PI(sta %twin_tmp1, [%g0] ASI_LEON_MMUREGS) ! store it
	285	SUN_PI_(sta %twin_tmp1, [%g0] ASI_M_MMUREGS) ! store it
1da177e4 LT	286
1da177e4 LT	287	mov AC_M_SFAR, %twin_tmp2
1ec8cf62 SR	288	LEON_PI(lda [%twin_tmp2] ASI_LEON_MMUREGS, %g0) ! read fault address
1ec8cf62 SR	289	SUN_PI_(lda [%twin_tmp2] ASI_M_MMUREGS, %g0) ! read fault address
1da177e4 LT	290
1da177e4 LT	291	mov AC_M_SFSR, %twin_tmp2
1ec8cf62 SR	292	LEON_PI(lda [%twin_tmp2] ASI_LEON_MMUREGS, %twin_tmp2) ! read fault status
	293	SUN_PI_(lda [%twin_tmp2] ASI_M_MMUREGS, %twin_tmp2) ! read fault status
	294	andcc %twin_tmp2, 0x2, %g0 ! did fault occur?
1da177e4	295
1ec8cf62	296	bne 1f ! yep, cleanup
1da177e4 LT	297	nop
	298
	299	wr %t_psr, 0x0, %psr
	300	nop
	301	b fwin_user_finish_up + 0x4
	302	nop
	303
	304	/* Did I ever tell you about my window lobotomy?
	305	* anyways... fwin_user_stack_is_bolixed expects
	306	* to be in window 'W' so make it happy or else
	307	* we watchdog badly.
	308	*/
	309	1:
	310	restore %g0, %g0, %g0
	311	b fwin_user_stack_is_bolixed ! oh well
	312	restore %g0, %g0, %g0