1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * wof.S: Sparc window overflow handler.
4 *
5 * Copyright (C) 1995 David S. Miller (davem@c
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 /* WARNING: This routine is hairy and _very_ c
19 * must be as fast as possible as it
20 * of register windows to the user an
21 * this code be _very_ careful as man
22 * kernel depend upon how this code b
23 * duly warned...
24 */
25
26 /* We define macro's for registers which have
27 * meaning throughout this entire routine. Th
28 * the comments mean that the register can onl
29 * accessed when in the 'trap' window, 'G' mea
30 * accessible in any window. Do not change th
31 * after they have been set, until you are rea
32 * from the trap.
33 */
34 #define t_psr l0 /* %psr at trap time
35 #define t_pc l1 /* PC for trap return
36 #define t_npc l2 /* NPC for trap return
37 #define t_wim l3 /* %wim at trap time
38 #define saved_g5 l5 /* Global save register
39 #define saved_g6 l6 /* Global save register
40 #define curptr g6 /* Gets set to 'current
41
42 /* Now registers whose values can change withi
43 #define twin_tmp l4 /* Temp reg, only usabl
44 #define glob_tmp g5 /* Global temporary reg
45
46 .text
47 .align 4
48 /* BEGINNING OF PATCH INSTRUCTIONS */
49 /* On a 7-window Sparc the boot code p
50 * instructions with the following one
51 */
52 .globl spnwin_patch1_7win, spnwin_pat
53 spnwin_patch1_7win: sll %t_wim, 6, %gl
54 spnwin_patch2_7win: and %glob_tmp, 0x7
55 spnwin_patch3_7win: and %twin_tmp, 0x7
56 /* END OF PATCH INSTRUCTIONS */
57
58 /* The trap entry point has done the f
59 *
60 * rd %psr, %l0
61 * rd %wim, %l3
62 * b spill_window_entry
63 * andcc %l0, PSR_PS, %g0
64 */
65
66 /* Datum current_thread_info->uwinmask
67 * where if any user windows are activ
68 * be set in to mask. If no user wind
69 * will be all zeroes.
70 */
71 .globl spill_window_entry
72 .globl spnwin_patch1, spnwin_patch2,
73 spill_window_entry:
74 /* LOCATION: Trap Window */
75
76 mov %g5, %saved_g5 ! save
77 mov %g6, %saved_g6 ! save
78
79 /* Compute what the new %wim will be i
80 * window properly in this trap handle
81 *
82 * newwim = ((%wim>>1) | (%wim<<(nwind
83 */
84 srl %t_wim, 0x1, %twin_tmp
85 spnwin_patch1: sll %t_wim, 7, %glob_tmp
86 or %glob_tmp, %twin_tmp,
87 spnwin_patch2: and %glob_tmp, 0xff, %glob
88
89 /* The trap entry point has set the co
90 * up for us to see if this is from us
91 * Get the load of 'curptr' out of the
92 */
93 LOAD_CURRENT(curptr, twin_tmp)
94
95 andcc %t_psr, PSR_PS, %g0
96 be,a spwin_fromuser
97 save %g0, %g0, %g0
98
99 /* See if any user windows are active
100 ld [%curptr + TI_UWINMASK], %twin
101 orcc %g0, %twin_tmp, %g0
102 bne spwin_exist_uwins
103 andn %twin_tmp, %glob_tmp, %twin_tm
104
105 /* Save into the window which must be
106 * Basically if we are here, this mean
107 * from kernel mode with only kernel w
108 * file.
109 */
110 save %g0, %g0, %g0 ! save
111 wr %glob_tmp, 0x0, %wim ! set
112
113 spwin_no_userwins_from_kernel:
114 /* LOCATION: Window to be saved */
115
116 STORE_WINDOW(sp) ! stas
117 restore %g0, %g0, %g0 ! go b
118
119 /* LOCATION: Trap window */
120 mov %saved_g5, %g5 ! rest
121 mov %saved_g6, %g6 ! rest
122 wr %t_psr, 0x0, %psr ! rest
123 WRITE_PAUSE ! wast
124 jmp %t_pc ! Retu
125 rett %t_npc ! we a
126
127 spwin_exist_uwins:
128 /* LOCATION: Trap window */
129
130 /* Wow, user windows have to be dealt
131 * and messy as all hell. And difficu
132 * are approaching the infamous regist
133 * problem for the first time. DON'T L
134 *
135 * Note that how the execution path wo
136 * will be left for us in the global t
137 * %glob_tmp. We cannot set the new %
138 * need to save into the appropriate w
139 * a trap (traps are off, we'd get a w
140 * But first, store the new user windo
141 * above.
142 */
143 st %twin_tmp, [%curptr + TI_UWINM
144 save %g0, %g0, %g0 ! Go t
145
146 spwin_fromuser:
147 /* LOCATION: Window to be saved */
148 wr %glob_tmp, 0x0, %wim ! Now
149
150 /* LOCATION: Window to be saved */
151
152 /* This instruction branches to a rout
153 * to validity of the users stack poin
154 * are necessary. This means that thi
155 * specific and thus this branch instr
156 * be patched at boot time once the ma
157 * This routine _shall not_ touch %cur
158 * circumstances whatsoever! It will
159 * label 'spwin_good_ustack' if the st
160 * needs to be dumped (SRMMU for insta
161 * do this) or 'spwin_finish_up' if th
162 * registers have already been saved.
163 * to be bogus for some reason the rou
164 * the label 'spwin_user_stack_is_boli
165 * care of things at that point.
166 */
167 b spwin_srmmu_stackchk
168 andcc %sp, 0x7, %g0
169
170 spwin_good_ustack:
171 /* LOCATION: Window to be saved */
172
173 /* The users stack is ok and we can sa
174 * %sp.
175 */
176 STORE_WINDOW(sp)
177
178 spwin_finish_up:
179 restore %g0, %g0, %g0 /* Bac
180
181 /* LOCATION: Trap window */
182
183 /* We have spilled successfully, and w
184 * the appropriate window onto the sta
185 */
186
187 /* Restore saved globals */
188 mov %saved_g5, %g5
189 mov %saved_g6, %g6
190
191 wr %t_psr, 0x0, %psr
192 WRITE_PAUSE
193 jmp %t_pc
194 rett %t_npc
195
196 spwin_user_stack_is_bolixed:
197 /* LOCATION: Window to be saved */
198
199 /* Wheee, user has trashed his/her sta
200 * how to proceed based upon whether w
201 * or not. If we came from kernel mod
202 * a special buffer and proceed, the k
203 * and we could be in an interrupt han
204 * If we came from user land we build
205 * c-code to gun down the process.
206 */
207 rd %psr, %glob_tmp
208 andcc %glob_tmp, PSR_PS, %g0
209 bne spwin_bad_ustack_from_kernel
210 nop
211
212 /* Oh well, throw this one window into
213 * buffer, the first one.
214 */
215 st %sp, [%curptr + TI_RWIN_SPTRS]
216 STORE_WINDOW(curptr + TI_REG_WINDOW)
217 restore %g0, %g0, %g0
218
219 /* LOCATION: Trap Window */
220
221 /* Back in the trap window, update win
222 mov 1, %twin_tmp
223 st %twin_tmp, [%curptr + TI_W_SAV
224
225 /* Compute new user window mas
226 * doing is taking two windows
227 * time and the one we attempt
228 * stack, and saying that ever
229 * window. umask = ((~(%t_wim
230 */
231 rd %wim, %twin_tmp
232 or %twin_tmp, %t_wim, %tw
233 not %twin_tmp
234 spnwin_patch3: and %twin_tmp, 0xff, %twin
235 st %twin_tmp, [%curptr +
236
237 #define STACK_OFFSET (THREAD_SIZE - TRACEREG_S
238
239 sethi %hi(STACK_OFFSET), %sp
240 or %sp, %lo(STACK_OFFSET), %sp
241 add %curptr, %sp, %sp
242
243 /* Restore the saved globals and build
244 mov %saved_g5, %g5
245 mov %saved_g6, %g6
246 STORE_PT_ALL(sp, t_psr, t_pc, t_npc, g
247
248 sethi %hi(STACK_OFFSET), %g6
249 or %g6, %lo(STACK_OFFSET), %g6
250 sub %sp, %g6, %g6 ! curp
251
252 /* Turn on traps and call c-code to de
253 wr %t_psr, PSR_ET, %psr
254 nop
255 call window_overflow_fault
256 nop
257
258 /* Return from trap if C-code actually
259 * doesn't then we never get this far
260 * be given the look of death from Com
261 */
262 b ret_trap_entry
263 clr %l6
264
265 spwin_bad_ustack_from_kernel:
266 /* LOCATION: Window to be saved */
267
268 /* The kernel provoked a spill window
269 * need to save is a user one and the
270 * stack pointer. We need to be quick
271 * a per-process window buffer until w
272 * this later on.
273 */
274 SAVE_BOLIXED_USER_STACK(curptr, glob_t
275 restore %g0, %g0, %g0
276
277 /* LOCATION: Trap window */
278
279 /* Restore globals, condition codes in
280 * return from trap. Note, restoring
281 * to kernel mode is not necessarily t
282 */
283 mov %saved_g5, %g5
284 mov %saved_g6, %g6
285
286 wr %t_psr, 0x0, %psr
287 WRITE_PAUSE
288
289 jmp %t_pc
290 rett %t_npc
291
292 /* Undefine the register macros which would on
293 * if used below. This helps find 'stupid' co
294 * produce 'odd' behavior. The routines below
295 * make usage of glob_tmp and t_psr so we leav
296 */
297 #undef twin_tmp
298 #undef curptr
299 #undef t_pc
300 #undef t_npc
301 #undef t_wim
302 #undef saved_g5
303 #undef saved_g6
304
305 /* Now come the per-architecture window overfl
306 * As noted above %curptr cannot be touched by
307 */
308
309 /* This is a generic SRMMU routine. A
310 * works for all current v8/srmmu impl
311 * see...
312 */
313 .globl spwin_srmmu_stackchk
314 spwin_srmmu_stackchk:
315 /* LOCATION: Window to be saved on the
316
317 /* Because of SMP concerns and speed w
318 * We disable fault traps in the MMU c
319 * Execute the stores, then check the
320 * to see what happens. I can hear Li
321 * "disgusting... broken hardware...".
322 *
323 * But first, check to see if the user
324 * up in kernel vma, then we would suc
325 * reason... ;( Note that the 'sethi'
326 * kernel is page aligned, which shoul
327 */
328 /* Check results of callers andcc %sp,
329 bne spwin_user_stack_is_bolixed
330 sethi %hi(PAGE_OFFSET), %glob_tmp
331 cmp %glob_tmp, %sp
332 bleu spwin_user_stack_is_bolixed
333 mov AC_M_SFSR, %glob_tmp
334
335 /* Clear the fault status and turn on
336 LEON_PI(lda [%glob_tmp] ASI_LEON_MMUREGS,
337 SUN_PI_(lda [%glob_tmp] ASI_M_MMUREGS, %g0
338
339 LEON_PI(lda [%g0] ASI_LEON_MMUREGS, %glob_
340 SUN_PI_(lda [%g0] ASI_M_MMUREGS, %glob_tmp
341 or %glob_tmp, 0x2, %glob_tmp
342 LEON_PI(sta %glob_tmp, [%g0] ASI_LEON_MMUR
343 SUN_PI_(sta %glob_tmp, [%g0] ASI_M_MMUREGS
344
345 /* Dump the registers and cross finger
346 STORE_WINDOW(sp)
347
348 /* Clear the no_fault bit and check th
349 andn %glob_tmp, 0x2, %glob_tmp
350 LEON_PI(sta %glob_tmp, [%g0] ASI_LEON_MMUR
351 SUN_PI_(sta %glob_tmp, [%g0] ASI_M_MMUREGS
352
353 mov AC_M_SFAR, %glob_tmp
354 LEON_PI(lda [%glob_tmp] ASI_LEON_MMUREGS,
355 SUN_PI_(lda [%glob_tmp] ASI_M_MMUREGS, %g0
356
357 mov AC_M_SFSR, %glob_tmp
358 LEON_PI(lda [%glob_tmp] ASI_LEON_MMUREGS,
359 SUN_PI_(lda [%glob_tmp] ASI_M_MMUREGS, %gl
360 andcc %glob_tmp, 0x2, %g0
361 be,a spwin_finish_up + 0x4
362 restore %g0, %g0, %g0
363
364 rd %psr, %glob_tmp
365 b spwin_user_stack_is_bolixed +
366 nop
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