1 /* $Id: etrap.S,v 1.16 1996/02/20 07:45:01 davem Exp $ 2 * etrap.S: Sparc trap window preparation for entry into the 3 * Linux kernel. 4 * 5 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu) 6 */ 7
8 #include <asm/cprefix.h>
9 #include <asm/head.h>
10 #include <asm/asi.h>
11 #include <asm/contregs.h>
12 #include <asm/page.h>
13 #include <asm/psr.h>
14 #include <asm/ptrace.h>
15 #include <asm/winmacro.h>
16
17 /* Registers to not touch at all. */ 18 #define t_psr l0 /* Set by caller */ 19 #define t_pc l1 /* Set by caller */ 20 #define t_npc l2 /* Set by caller */ 21 #define t_wim l3 /* Set by caller */ 22 #define t_twinmask l4 /* Set at beginning of this entry routine. */ 23 #define t_kstack l5 /* Set right before pt_regs frame is built */ 24 #define t_retpc l6 /* If you change this, change winmacro.h header file */ 25 #define t_systable l7 /* Never touch this, could be the syscall table ptr. */ 26 #define curptr g4 /* Set after pt_regs frame is built */ 27
28 .text
29 .align 4
30
31 /* SEVEN WINDOW PATCH INSTRUCTIONS */ 32 .globl tsetup_7win_patch1, tsetup_7win_patch2
33 .globl tsetup_7win_patch3, tsetup_7win_patch4
34 .globl tsetup_7win_patch5, tsetup_7win_patch6
35 tsetup_7win_patch1: sll %t_wim, 0x6, %t_wim
36 tsetup_7win_patch2: and %g2, 0x7f, %g2
37 tsetup_7win_patch3: and %g2, 0x7f, %g2
38 tsetup_7win_patch4: and %g1, 0x7f, %g1
39 tsetup_7win_patch5: sll %t_wim, 0x6, %t_wim
40 tsetup_7win_patch6: and %g2, 0x7f, %g2
41 /* END OF PATCH INSTRUCTIONS */ 42
43 /* At trap time, interrupts and all generic traps do the 44 * following: 45 * 46 * rd %psr, %l0 47 * b some_handler 48 * rd %wim, %l3 49 * nop 50 * 51 * Then 'some_handler' if it needs a trap frame (ie. it has 52 * to call c-code and the trap cannot be handled in-window) 53 * then it does the SAVE_ALL macro in entry.S which does 54 * 55 * sethi %hi(trap_setup), %l4 56 * jmpl %l4 + %lo(trap_setup), %l6 57 * mov 1, %l4 58 */ 59
60 /* 2 3 4 window number 61 * ----- 62 * O T S mnemonic 63 * 64 * O == Current window before trap 65 * T == Window entered when trap occurred 66 * S == Window we will need to save if (1<<T) == %wim 67 * 68 * Before execution gets here, it must be guarenteed that 69 * %l0 contains trap time %psr, %l1 and %l2 contain the 70 * trap pc and npc, and %l3 contains the trap time %wim. 71 */ 72
73 .globl trap_setup, tsetup_patch1, tsetup_patch2
74 .globl tsetup_patch3, tsetup_patch4
75 .globl tsetup_patch5, tsetup_patch6
76 trap_setup:
77 /* Calculate mask of trap window. See if from user 78 * or kernel and branch conditionally. 79 */ 80 mov 1, %t_twinmask
81 sll %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr)
82 andcc %t_psr, PSR_PS, %g0 ! fromsupv_p = (psr & PSR_PS)
83 be trap_setup_from_user ! nope, from user mode
84 nop
85
86 /* From kernel, allocate more kernel stack and 87 * build a pt_regs trap frame. 88 */ 89 sub %fp, (REGWIN_SZ + TRACEREG_SZ), %t_kstack
90 STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2)
91
92 /* See if we are in the trap window. */ 93 andcc %t_twinmask, %t_wim, %g0
94 be 1f
95 nop
96
97 b trap_setup_kernel_spill ! in trap window, clean up
98 nop
99
100 /* Trap from kernel with a window available. 101 * Just do it... 102 */ 103 1:
104 jmpl %t_retpc + 0x8, %g0 ! return to caller
105 mov %t_kstack, %sp ! jump onto new stack
106
107 trap_setup_kernel_spill:
108 LOAD_CURRENT(curptr, g1)
109 ld [%curptr + THREAD_UMASK], %g1
110 orcc %g0, %g1, %g0
111 bne trap_setup_user_spill ! there are some user windows, yuck
112 nop
113
114 /* Spill from kernel, but only kernel windows, adjust 115 * %wim and go. 116 */ 117 srl %t_wim, 0x1, %g2 ! begin computation of new %wim
118 tsetup_patch1: sll %t_wim, 0x7, %t_wim ! patched on 7 window Sparcs
119 or %t_wim, %g2, %g2
120 tsetup_patch2: and %g2, 0xff, %g2 ! patched on 7 window Sparcs
121
122 save %g0, %g0, %g0
123
124 /* Set new %wim value */ 125 wr %g2, 0x0, %wim
126 WRITE_PAUSE
127
128 /* Save the kernel window onto the corresponding stack. */ 129 STORE_WINDOW(sp)
130
131 restore %g0, %g0, %g0
132
133 jmpl %t_retpc + 0x8, %g0 ! return to caller
134 mov %t_kstack, %sp ! and onto new kernel stack
135
136 trap_setup_from_user:
137 /* We can't use %curptr yet. */ 138 LOAD_CURRENT(t_kstack, t_twinmask)
139 mov 1, %t_twinmask
140 ld [%t_kstack + TASK_SAVED_KSTACK], %t_kstack
141 sll %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr)
142
143 /* Build pt_regs frame. */ 144 STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2)
145
146 /* Clear current->tss.w_saved */ 147 LOAD_CURRENT(curptr, g1)
148 st %g0, [%curptr + THREAD_W_SAVED]
149
150 /* See if we are in the trap window. */ 151 andcc %t_twinmask, %t_wim, %g0
152 bne trap_setup_user_spill ! yep we are
153 orn %g0, %t_twinmask, %g1 ! negate trap win mask into %g1
154
155 /* Trap from user, but not into the invalid window. 156 * Calculate new umask. The way this works is, 157 * any window from the %wim at trap time until 158 * the window right before the one we are in now, 159 * is a user window. A diagram: 160 * 161 * 7 6 5 4 3 2 1 0 window number 162 * --------------- 163 * I L T mnemonic 164 * 165 * Window 'I' is the invalid window in our example, 166 * window 'L' is the window the user was in when 167 * the trap occurred, window T is the trap window 168 * we are in now. So therefore, windows 5, 4 and 169 * 3 are user windows. The following sequence 170 * computes the user winmask to represent this. 171 */ 172 subcc %t_wim, %t_twinmask, %g2
173 bneg,a 1f
174 sub %g2, 0x1, %g2
175 1:
176 andn %g2, %t_twinmask, %g2
177 tsetup_patch3: and %g2, 0xff, %g2 ! patched on 7win Sparcs
178 st %g2, [%curptr + THREAD_UMASK] ! store new umask
179
180 jmpl %t_retpc + 0x8, %g0 ! return to caller
181 mov %t_kstack, %sp ! and onto kernel stack
182
183 trap_setup_user_spill:
184 /* A spill occured from either kernel or user mode 185 * and there exist some user windows to deal with. 186 * A mask of the currently valid user windows 187 * is in %g1 upon entry to here. 188 */ 189
190 tsetup_patch4: and %g1, 0xff, %g1 ! patched on 7win Sparcs, mask
191 srl %t_wim, 0x1, %g2 ! compute new %wim
192 tsetup_patch5: sll %t_wim, 0x7, %t_wim ! patched on 7win Sparcs
193 or %t_wim, %g2, %g2 ! %g2 is new %wim
194 tsetup_patch6: and %g2, 0xff, %g2 ! patched on 7win Sparcs
195 andn %g1, %g2, %g1 ! clear this bit in %g1
196 st %g1, [%curptr + THREAD_UMASK]
197
198 save %g0, %g0, %g0
199
200 wr %g2, 0x0, %wim
201 WRITE_PAUSE
202
203 /* Call MMU-architecture dependant stack checking 204 * routine. 205 */ 206 .globl C_LABEL(tsetup_mmu_patchme)
207 C_LABEL(tsetup_mmu_patchme): b C_LABEL(tsetup_sun4c_stackchk)
208 andcc %sp, 0x7, %g0
209
210 trap_setup_user_stack_is_bolixed:
211 /* From user/kernel into invalid window w/bad user 212 * stack. Save bad user stack, and return to caller. 213 */ 214 SAVE_BOLIXED_USER_STACK(curptr, g3)
215 restore %g0, %g0, %g0
216
217 jmpl %t_retpc + 0x8, %g0
218 mov %t_kstack, %sp
219
220 trap_setup_good_ustack:
221 STORE_WINDOW(sp)
222
223 trap_setup_finish_up:
224 restore %g0, %g0, %g0
225
226 jmpl %t_retpc + 0x8, %g0
227 mov %t_kstack, %sp
228
229 /* Architecture specific stack checking routines. When either 230 * of these routines are called, the globals are free to use 231 * as they have been safely stashed on the new kernel stack 232 * pointer. Thus the definition below for simplicity. 233 */ 234 #define glob_tmp g1
235
236 .globl C_LABEL(tsetup_sun4c_stackchk)
237 C_LABEL(tsetup_sun4c_stackchk):
238 /* Done by caller: andcc %sp, 0x7, %g0 */ 239 be 1f
240 sra %sp, 29, %glob_tmp
241
242 b trap_setup_user_stack_is_bolixed
243 nop
244
245 1:
246 add %glob_tmp, 0x1, %glob_tmp
247 andncc %glob_tmp, 0x1, %g0
248 be 1f
249 and %sp, 0xfff, %glob_tmp ! delay slot
250
251 b trap_setup_user_stack_is_bolixed
252 nop
253
254 /* See if our dump area will be on more than one 255 * page. 256 */ 257 1:
258 add %glob_tmp, 0x38, %glob_tmp
259 andncc %glob_tmp, 0xff8, %g0
260 be tsetup_sun4c_onepage ! only one page to check
261 lda [%sp] ASI_PTE, %glob_tmp ! have to check first page anyways
262
263 tsetup_sun4c_twopages:
264 /* Is first page ok permission wise? */ 265 srl %glob_tmp, 29, %glob_tmp
266 cmp %glob_tmp, 0x6
267 be 1f
268 add %sp, 0x38, %glob_tmp /* Is second page in vma hole? */ 269
270 b trap_setup_user_stack_is_bolixed
271 nop
272
273 1:
274 sra %glob_tmp, 29, %glob_tmp
275 add %glob_tmp, 0x1, %glob_tmp
276 andncc %glob_tmp, 0x1, %g0
277 be 1f
278 add %sp, 0x38, %glob_tmp
279
280 b trap_setup_user_stack_is_bolixed
281 nop
282
283 1:
284 lda [%glob_tmp] ASI_PTE, %glob_tmp
285
286 tsetup_sun4c_onepage:
287 srl %glob_tmp, 29, %glob_tmp
288 cmp %glob_tmp, 0x6 ! can user write to it?
289 be trap_setup_good_ustack ! success
290 nop
291
292 b trap_setup_user_stack_is_bolixed
293 nop
294
295 .globl C_LABEL(tsetup_srmmu_stackchk)
296 C_LABEL(tsetup_srmmu_stackchk):
297 /* Check results of callers andcc %sp, 0x7, %g0 */ 298 bne trap_setup_user_stack_is_bolixed
299 sethi %hi(KERNBASE), %glob_tmp
300 cmp %glob_tmp, %sp
301 bleu trap_setup_user_stack_is_bolixed
302 nop
303
304 /* Clear the fault status and turn on the no_fault bit. */ 305 lda [%g0] ASI_M_MMUREGS, %glob_tmp ! read MMU control
306 or %glob_tmp, 0x2, %glob_tmp ! or in no_fault bit
307 sta %glob_tmp, [%g0] ASI_M_MMUREGS ! set it
308
309 /* Dump the registers and cross fingers. */ 310 STORE_WINDOW(sp)
311
312 /* Clear the no_fault bit and check the status. */ 313 andn %glob_tmp, 0x2, %glob_tmp
314 sta %glob_tmp, [%g0] ASI_M_MMUREGS
315 mov AC_M_SFAR, %glob_tmp
316 lda [%glob_tmp] ASI_M_MMUREGS, %g0
317 mov AC_M_SFSR, %glob_tmp
318 lda [%glob_tmp] ASI_M_MMUREGS, %glob_tmp ! save away status of winstore
319 andcc %glob_tmp, 0x2, %g0 ! did we fault?
320 be trap_setup_finish_up ! cool beans, success
321 nop
322
323 b trap_setup_user_stack_is_bolixed ! we faulted, ugh
324 nop
325
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