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