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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * wuf.S: Window underflow trap handler for the Sparc.
4 *
5 * Copyright (C) 1995 David S. Miller
6 */
7
8#include <asm/contregs.h>
9#include <asm/page.h>
10#include <asm/ptrace.h>
11#include <asm/psr.h>
12#include <asm/smp.h>
13#include <asm/asi.h>
14#include <asm/winmacro.h>
15#include <asm/asmmacro.h>
16#include <asm/thread_info.h>
17
18/* Just like the overflow handler we define macros for registers
19 * with fixed meanings in this routine.
20 */
21#define t_psr l0
22#define t_pc l1
23#define t_npc l2
24#define t_wim l3
25/* Don't touch the above registers or else you die horribly... */
26
27/* Now macros for the available scratch registers in this routine. */
28#define twin_tmp1 l4
29#define twin_tmp2 l5
30
31#define curptr g6
32
33 .text
34 .align 4
35
36 /* The trap entry point has executed the following:
37 *
38 * rd %psr, %l0
39 * rd %wim, %l3
40 * b fill_window_entry
41 * andcc %l0, PSR_PS, %g0
42 */
43
44 /* Datum current_thread_info->uwinmask contains at all times a bitmask
45 * where if any user windows are active, at least one bit will
46 * be set in to mask. If no user windows are active, the bitmask
47 * will be all zeroes.
48 */
49
50 /* To get an idea of what has just happened to cause this
51 * trap take a look at this diagram:
52 *
53 * 1 2 3 4 <-- Window number
54 * ----------
55 * T O W I <-- Symbolic name
56 *
57 * O == the window that execution was in when
58 * the restore was attempted
59 *
60 * T == the trap itself has save'd us into this
61 * window
62 *
63 * W == this window is the one which is now invalid
64 * and must be made valid plus loaded from the
65 * stack
66 *
67 * I == this window will be the invalid one when we
68 * are done and return from trap if successful
69 */
70
71 /* BEGINNING OF PATCH INSTRUCTIONS */
72
73 /* On 7-window Sparc the boot code patches fnwin_patch1
74 * with the following instruction.
75 */
76 .globl fnwin_patch1_7win, fnwin_patch2_7win
77fnwin_patch1_7win: srl %t_wim, 6, %twin_tmp2
78fnwin_patch2_7win: and %twin_tmp1, 0x7f, %twin_tmp1
79 /* END OF PATCH INSTRUCTIONS */
80
81 .globl fill_window_entry, fnwin_patch1, fnwin_patch2
82fill_window_entry:
83 /* LOCATION: Window 'T' */
84
85 /* Compute what the new %wim is going to be if we retrieve
86 * the proper window off of the stack.
87 */
88 sll %t_wim, 1, %twin_tmp1
89fnwin_patch1: srl %t_wim, 7, %twin_tmp2
90 or %twin_tmp1, %twin_tmp2, %twin_tmp1
91fnwin_patch2: and %twin_tmp1, 0xff, %twin_tmp1
92
93 wr %twin_tmp1, 0x0, %wim /* Make window 'I' invalid */
94
95 andcc %t_psr, PSR_PS, %g0
96 be fwin_from_user
97 restore %g0, %g0, %g0 /* Restore to window 'O' */
98
99 /* Trapped from kernel, we trust that the kernel does not
100 * 'over restore' sorta speak and just grab the window
101 * from the stack and return. Easy enough.
102 */
103fwin_from_kernel:
104 /* LOCATION: Window 'O' */
105
106 restore %g0, %g0, %g0
107
108 /* LOCATION: Window 'W' */
109
110 LOAD_WINDOW(sp) /* Load it up */
111
112 /* Spin the wheel... */
113 save %g0, %g0, %g0
114 save %g0, %g0, %g0
115 /* I'd like to buy a vowel please... */
116
117 /* LOCATION: Window 'T' */
118
119 /* Now preserve the condition codes in %psr, pause, and
120 * return from trap. This is the simplest case of all.
121 */
122 wr %t_psr, 0x0, %psr
123 WRITE_PAUSE
124
125 jmp %t_pc
126 rett %t_npc
127
128fwin_from_user:
129 /* LOCATION: Window 'O' */
130
131 restore %g0, %g0, %g0 /* Restore to window 'W' */
132
133 /* LOCATION: Window 'W' */
134
135 /* Branch to the stack validation routine */
136 b srmmu_fwin_stackchk
137 andcc %sp, 0x7, %g0
138
139#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ)
140
141fwin_user_stack_is_bolixed:
142 /* LOCATION: Window 'W' */
143
144 /* Place a pt_regs frame on the kernel stack, save back
145 * to the trap window and call c-code to deal with this.
146 */
147 LOAD_CURRENT(l4, l5)
148
149 sethi %hi(STACK_OFFSET), %l5
150 or %l5, %lo(STACK_OFFSET), %l5
151 add %l4, %l5, %l5
152
153 /* Store globals into pt_regs frame. */
154 STORE_PT_GLOBALS(l5)
155 STORE_PT_YREG(l5, g3)
156
157 /* Save current in a global while we change windows. */
158 mov %l4, %curptr
159
160 save %g0, %g0, %g0
161
162 /* LOCATION: Window 'O' */
163
164 rd %psr, %g3 /* Read %psr in live user window */
165 mov %fp, %g4 /* Save bogus frame pointer. */
166
167 save %g0, %g0, %g0
168
169 /* LOCATION: Window 'T' */
170
171 sethi %hi(STACK_OFFSET), %l5
172 or %l5, %lo(STACK_OFFSET), %l5
173 add %curptr, %l5, %sp
174
175 /* Build rest of pt_regs. */
176 STORE_PT_INS(sp)
177 STORE_PT_PRIV(sp, t_psr, t_pc, t_npc)
178
179 /* re-set trap time %wim value */
180 wr %t_wim, 0x0, %wim
181
182 /* Fix users window mask and buffer save count. */
183 mov 0x1, %g5
184 sll %g5, %g3, %g5
185 st %g5, [%curptr + TI_UWINMASK] ! one live user window still
186 st %g0, [%curptr + TI_W_SAVED] ! no windows in the buffer
187
188 wr %t_psr, PSR_ET, %psr ! enable traps
189 nop
190 call window_underflow_fault
191 mov %g4, %o0
192
193 b ret_trap_entry
194 clr %l6
195
196fwin_user_stack_is_ok:
197 /* LOCATION: Window 'W' */
198
199 /* The users stack area is kosher and mapped, load the
200 * window and fall through to the finish up routine.
201 */
202 LOAD_WINDOW(sp)
203
204 /* Round and round she goes... */
205 save %g0, %g0, %g0 /* Save to window 'O' */
206 save %g0, %g0, %g0 /* Save to window 'T' */
207 /* Where she'll trap nobody knows... */
208
209 /* LOCATION: Window 'T' */
210
211fwin_user_finish_up:
212 /* LOCATION: Window 'T' */
213
214 wr %t_psr, 0x0, %psr
215 WRITE_PAUSE
216
217 jmp %t_pc
218 rett %t_npc
219
220 /* Here come the architecture specific checks for stack.
221 * mappings. Note that unlike the window overflow handler
222 * we only need to check whether the user can read from
223 * the appropriate addresses. Also note that we are in
224 * an invalid window which will be loaded, and this means
225 * that until we actually load the window up we are free
226 * to use any of the local registers contained within.
227 *
228 * On success these routine branch to fwin_user_stack_is_ok
229 * if the area at %sp is user readable and the window still
230 * needs to be loaded, else fwin_user_finish_up if the
231 * routine has done the loading itself. On failure (bogus
232 * user stack) the routine shall branch to the label called
233 * fwin_user_stack_is_bolixed.
234 *
235 * Contrary to the arch-specific window overflow stack
236 * check routines in wof.S, these routines are free to use
237 * any of the local registers they want to as this window
238 * does not belong to anyone at this point, however the
239 * outs and ins are still verboten as they are part of
240 * 'someone elses' window possibly.
241 */
242
243 .globl srmmu_fwin_stackchk
244srmmu_fwin_stackchk:
245 /* LOCATION: Window 'W' */
246
247 /* Caller did 'andcc %sp, 0x7, %g0' */
248 bne fwin_user_stack_is_bolixed
249 sethi %hi(PAGE_OFFSET), %l5
250
251 /* Check if the users stack is in kernel vma, then our
252 * trial and error technique below would succeed for
253 * the 'wrong' reason.
254 */
255 mov AC_M_SFSR, %l4
256 cmp %l5, %sp
257 bleu fwin_user_stack_is_bolixed
258LEON_PI( lda [%l4] ASI_LEON_MMUREGS, %g0) ! clear fault status
259SUN_PI_( lda [%l4] ASI_M_MMUREGS, %g0) ! clear fault status
260
261 /* The technique is, turn off faults on this processor,
262 * just let the load rip, then check the sfsr to see if
263 * a fault did occur. Then we turn on fault traps again
264 * and branch conditionally based upon what happened.
265 */
266LEON_PI(lda [%g0] ASI_LEON_MMUREGS, %l5) ! read mmu-ctrl reg
267SUN_PI_(lda [%g0] ASI_M_MMUREGS, %l5) ! read mmu-ctrl reg
268 or %l5, 0x2, %l5 ! turn on no-fault bit
269LEON_PI(sta %l5, [%g0] ASI_LEON_MMUREGS) ! store it
270SUN_PI_(sta %l5, [%g0] ASI_M_MMUREGS) ! store it
271
272 /* Cross fingers and go for it. */
273 LOAD_WINDOW(sp)
274
275 /* A penny 'saved'... */
276 save %g0, %g0, %g0
277 save %g0, %g0, %g0
278 /* Is a BADTRAP earned... */
279
280 /* LOCATION: Window 'T' */
281
282LEON_PI(lda [%g0] ASI_LEON_MMUREGS, %twin_tmp1) ! load mmu-ctrl again
283SUN_PI_(lda [%g0] ASI_M_MMUREGS, %twin_tmp1) ! load mmu-ctrl again
284 andn %twin_tmp1, 0x2, %twin_tmp1 ! clear no-fault bit
285LEON_PI(sta %twin_tmp1, [%g0] ASI_LEON_MMUREGS) ! store it
286SUN_PI_(sta %twin_tmp1, [%g0] ASI_M_MMUREGS) ! store it
287
288 mov AC_M_SFAR, %twin_tmp2
289LEON_PI(lda [%twin_tmp2] ASI_LEON_MMUREGS, %g0) ! read fault address
290SUN_PI_(lda [%twin_tmp2] ASI_M_MMUREGS, %g0) ! read fault address
291
292 mov AC_M_SFSR, %twin_tmp2
293LEON_PI(lda [%twin_tmp2] ASI_LEON_MMUREGS, %twin_tmp2) ! read fault status
294SUN_PI_(lda [%twin_tmp2] ASI_M_MMUREGS, %twin_tmp2) ! read fault status
295 andcc %twin_tmp2, 0x2, %g0 ! did fault occur?
296
297 bne 1f ! yep, cleanup
298 nop
299
300 wr %t_psr, 0x0, %psr
301 nop
302 b fwin_user_finish_up + 0x4
303 nop
304
305 /* Did I ever tell you about my window lobotomy?
306 * anyways... fwin_user_stack_is_bolixed expects
307 * to be in window 'W' so make it happy or else
308 * we watchdog badly.
309 */
3101:
311 restore %g0, %g0, %g0
312 b fwin_user_stack_is_bolixed ! oh well
313 restore %g0, %g0, %g0
1/*
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
76fnwin_patch1_7win: srl %t_wim, 6, %twin_tmp2
77fnwin_patch2_7win: and %twin_tmp1, 0x7f, %twin_tmp1
78 /* END OF PATCH INSTRUCTIONS */
79
80 .globl fill_window_entry, fnwin_patch1, fnwin_patch2
81fill_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
88fnwin_patch1: srl %t_wim, 7, %twin_tmp2
89 or %twin_tmp1, %twin_tmp2, %twin_tmp1
90fnwin_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 */
102fwin_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
127fwin_from_user:
128 /* LOCATION: Window 'O' */
129
130 restore %g0, %g0, %g0 /* Restore to window 'W' */
131
132 /* LOCATION: Window 'W' */
133
134 /* Branch to the architecture specific stack validation
135 * routine. They can be found below...
136 */
137 .globl fwin_mmu_patchme
138fwin_mmu_patchme: b sun4c_fwin_stackchk
139 andcc %sp, 0x7, %g0
140
141#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ)
142
143fwin_user_stack_is_bolixed:
144 /* LOCATION: Window 'W' */
145
146 /* Place a pt_regs frame on the kernel stack, save back
147 * to the trap window and call c-code to deal with this.
148 */
149 LOAD_CURRENT(l4, l5)
150
151 sethi %hi(STACK_OFFSET), %l5
152 or %l5, %lo(STACK_OFFSET), %l5
153 add %l4, %l5, %l5
154
155 /* Store globals into pt_regs frame. */
156 STORE_PT_GLOBALS(l5)
157 STORE_PT_YREG(l5, g3)
158
159 /* Save current in a global while we change windows. */
160 mov %l4, %curptr
161
162 save %g0, %g0, %g0
163
164 /* LOCATION: Window 'O' */
165
166 rd %psr, %g3 /* Read %psr in live user window */
167 mov %fp, %g4 /* Save bogus frame pointer. */
168
169 save %g0, %g0, %g0
170
171 /* LOCATION: Window 'T' */
172
173 sethi %hi(STACK_OFFSET), %l5
174 or %l5, %lo(STACK_OFFSET), %l5
175 add %curptr, %l5, %sp
176
177 /* Build rest of pt_regs. */
178 STORE_PT_INS(sp)
179 STORE_PT_PRIV(sp, t_psr, t_pc, t_npc)
180
181 /* re-set trap time %wim value */
182 wr %t_wim, 0x0, %wim
183
184 /* Fix users window mask and buffer save count. */
185 mov 0x1, %g5
186 sll %g5, %g3, %g5
187 st %g5, [%curptr + TI_UWINMASK] ! one live user window still
188 st %g0, [%curptr + TI_W_SAVED] ! no windows in the buffer
189
190 wr %t_psr, PSR_ET, %psr ! enable traps
191 nop
192 call window_underflow_fault
193 mov %g4, %o0
194
195 b ret_trap_entry
196 clr %l6
197
198fwin_user_stack_is_ok:
199 /* LOCATION: Window 'W' */
200
201 /* The users stack area is kosher and mapped, load the
202 * window and fall through to the finish up routine.
203 */
204 LOAD_WINDOW(sp)
205
206 /* Round and round she goes... */
207 save %g0, %g0, %g0 /* Save to window 'O' */
208 save %g0, %g0, %g0 /* Save to window 'T' */
209 /* Where she'll trap nobody knows... */
210
211 /* LOCATION: Window 'T' */
212
213fwin_user_finish_up:
214 /* LOCATION: Window 'T' */
215
216 wr %t_psr, 0x0, %psr
217 WRITE_PAUSE
218
219 jmp %t_pc
220 rett %t_npc
221
222 /* Here come the architecture specific checks for stack.
223 * mappings. Note that unlike the window overflow handler
224 * we only need to check whether the user can read from
225 * the appropriate addresses. Also note that we are in
226 * an invalid window which will be loaded, and this means
227 * that until we actually load the window up we are free
228 * to use any of the local registers contained within.
229 *
230 * On success these routine branch to fwin_user_stack_is_ok
231 * if the area at %sp is user readable and the window still
232 * needs to be loaded, else fwin_user_finish_up if the
233 * routine has done the loading itself. On failure (bogus
234 * user stack) the routine shall branch to the label called
235 * fwin_user_stack_is_bolixed.
236 *
237 * Contrary to the arch-specific window overflow stack
238 * check routines in wof.S, these routines are free to use
239 * any of the local registers they want to as this window
240 * does not belong to anyone at this point, however the
241 * outs and ins are still verboten as they are part of
242 * 'someone elses' window possibly.
243 */
244
245 .align 4
246sun4c_fwin_stackchk:
247 /* LOCATION: Window 'W' */
248
249 /* Caller did 'andcc %sp, 0x7, %g0' */
250 be 1f
251 and %sp, 0xfff, %l0 ! delay slot
252
253 b,a fwin_user_stack_is_bolixed
254
255 /* See if we have to check the sanity of one page or two */
2561:
257 add %l0, 0x38, %l0
258 sra %sp, 29, %l5
259 add %l5, 0x1, %l5
260 andncc %l5, 0x1, %g0
261 be 1f
262 andncc %l0, 0xff8, %g0
263
264 b,a fwin_user_stack_is_bolixed /* %sp is in vma hole, yuck */
265
2661:
267 be sun4c_fwin_onepage /* Only one page to check */
268 lda [%sp] ASI_PTE, %l1
269sun4c_fwin_twopages:
270 add %sp, 0x38, %l0
271 sra %l0, 29, %l5
272 add %l5, 0x1, %l5
273 andncc %l5, 0x1, %g0
274 be 1f
275 lda [%l0] ASI_PTE, %l1
276
277 b,a fwin_user_stack_is_bolixed /* Second page in vma hole */
278
2791:
280 srl %l1, 29, %l1
281 andcc %l1, 0x4, %g0
282 bne sun4c_fwin_onepage
283 lda [%sp] ASI_PTE, %l1
284
285 b,a fwin_user_stack_is_bolixed /* Second page has bad perms */
286
287sun4c_fwin_onepage:
288 srl %l1, 29, %l1
289 andcc %l1, 0x4, %g0
290 bne fwin_user_stack_is_ok
291 nop
292
293 /* A page had bad page permissions, losing... */
294 b,a fwin_user_stack_is_bolixed
295
296 .globl srmmu_fwin_stackchk
297srmmu_fwin_stackchk:
298 /* LOCATION: Window 'W' */
299
300 /* Caller did 'andcc %sp, 0x7, %g0' */
301 bne fwin_user_stack_is_bolixed
302 sethi %hi(PAGE_OFFSET), %l5
303
304 /* Check if the users stack is in kernel vma, then our
305 * trial and error technique below would succeed for
306 * the 'wrong' reason.
307 */
308 mov AC_M_SFSR, %l4
309 cmp %l5, %sp
310 bleu fwin_user_stack_is_bolixed
311 lda [%l4] ASI_M_MMUREGS, %g0 ! clear fault status
312
313 /* The technique is, turn off faults on this processor,
314 * just let the load rip, then check the sfsr to see if
315 * a fault did occur. Then we turn on fault traps again
316 * and branch conditionally based upon what happened.
317 */
318 lda [%g0] ASI_M_MMUREGS, %l5 ! read mmu-ctrl reg
319 or %l5, 0x2, %l5 ! turn on no-fault bit
320 sta %l5, [%g0] ASI_M_MMUREGS ! store it
321
322 /* Cross fingers and go for it. */
323 LOAD_WINDOW(sp)
324
325 /* A penny 'saved'... */
326 save %g0, %g0, %g0
327 save %g0, %g0, %g0
328 /* Is a BADTRAP earned... */
329
330 /* LOCATION: Window 'T' */
331
332 lda [%g0] ASI_M_MMUREGS, %twin_tmp1 ! load mmu-ctrl again
333 andn %twin_tmp1, 0x2, %twin_tmp1 ! clear no-fault bit
334 sta %twin_tmp1, [%g0] ASI_M_MMUREGS ! store it
335
336 mov AC_M_SFAR, %twin_tmp2
337 lda [%twin_tmp2] ASI_M_MMUREGS, %g0 ! read fault address
338
339 mov AC_M_SFSR, %twin_tmp2
340 lda [%twin_tmp2] ASI_M_MMUREGS, %twin_tmp2 ! read fault status
341 andcc %twin_tmp2, 0x2, %g0 ! did fault occur?
342
343 bne 1f ! yep, cleanup
344 nop
345
346 wr %t_psr, 0x0, %psr
347 nop
348 b fwin_user_finish_up + 0x4
349 nop
350
351 /* Did I ever tell you about my window lobotomy?
352 * anyways... fwin_user_stack_is_bolixed expects
353 * to be in window 'W' so make it happy or else
354 * we watchdog badly.
355 */
3561:
357 restore %g0, %g0, %g0
358 b fwin_user_stack_is_bolixed ! oh well
359 restore %g0, %g0, %g0