summaryrefslogtreecommitdiffstats
path: root/arch/sparc/kernel/etrap_32.S
blob: e3e80d65e39af1d9167a7ca3156ee2f797112a6c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
/*
 * etrap.S: Sparc trap window preparation for entry into the
 *          Linux kernel.
 *
 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
 */

#include <asm/head.h>
#include <asm/asi.h>
#include <asm/contregs.h>
#include <asm/page.h>
#include <asm/psr.h>
#include <asm/ptrace.h>
#include <asm/winmacro.h>
#include <asm/asmmacro.h>
#include <asm/thread_info.h>

/* Registers to not touch at all. */
#define t_psr        l0 /* Set by caller */
#define t_pc         l1 /* Set by caller */
#define t_npc        l2 /* Set by caller */
#define t_wim        l3 /* Set by caller */
#define t_twinmask   l4 /* Set at beginning of this entry routine. */
#define t_kstack     l5 /* Set right before pt_regs frame is built */
#define t_retpc      l6 /* If you change this, change winmacro.h header file */
#define t_systable   l7 /* Never touch this, could be the syscall table ptr. */
#define curptr       g6 /* Set after pt_regs frame is built */

	.text
	.align 4

	/* SEVEN WINDOW PATCH INSTRUCTIONS */
	.globl	tsetup_7win_patch1, tsetup_7win_patch2
	.globl	tsetup_7win_patch3, tsetup_7win_patch4
	.globl	tsetup_7win_patch5, tsetup_7win_patch6
tsetup_7win_patch1:	sll	%t_wim, 0x6, %t_wim
tsetup_7win_patch2:	and	%g2, 0x7f, %g2
tsetup_7win_patch3:	and	%g2, 0x7f, %g2
tsetup_7win_patch4:	and	%g1, 0x7f, %g1
tsetup_7win_patch5:	sll	%t_wim, 0x6, %t_wim
tsetup_7win_patch6:	and	%g2, 0x7f, %g2
	/* END OF PATCH INSTRUCTIONS */

	/* At trap time, interrupts and all generic traps do the
	 * following:
	 *
	 * rd	%psr, %l0
	 * b	some_handler
	 * rd	%wim, %l3
	 * nop
	 *
	 * Then 'some_handler' if it needs a trap frame (ie. it has
	 * to call c-code and the trap cannot be handled in-window)
	 * then it does the SAVE_ALL macro in entry.S which does
	 *
	 * sethi	%hi(trap_setup), %l4
	 * jmpl		%l4 + %lo(trap_setup), %l6
	 * nop
	 */

	/* 2 3 4  window number
	 * -----
	 * O T S  mnemonic
	 *
	 * O == Current window before trap
	 * T == Window entered when trap occurred
	 * S == Window we will need to save if (1<<T) == %wim
	 *
	 * Before execution gets here, it must be guaranteed that
	 * %l0 contains trap time %psr, %l1 and %l2 contain the
	 * trap pc and npc, and %l3 contains the trap time %wim.
	 */

	.globl	trap_setup, tsetup_patch1, tsetup_patch2
	.globl	tsetup_patch3, tsetup_patch4
	.globl	tsetup_patch5, tsetup_patch6
trap_setup:
	/* Calculate mask of trap window.  See if from user
	 * or kernel and branch conditionally.
	 */
	mov	1, %t_twinmask
	andcc	%t_psr, PSR_PS, %g0		 ! fromsupv_p = (psr & PSR_PS)
	be	trap_setup_from_user		 ! nope, from user mode
	 sll	%t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr)

	/* From kernel, allocate more kernel stack and
	 * build a pt_regs trap frame.
	 */
	sub	%fp, (STACKFRAME_SZ + TRACEREG_SZ), %t_kstack
	STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2)

	/* See if we are in the trap window. */
	andcc	%t_twinmask, %t_wim, %g0
	bne	trap_setup_kernel_spill		! in trap window, clean up
	 nop

	/* Trap from kernel with a window available.
	 * Just do it...
	 */
	jmpl	%t_retpc + 0x8, %g0	! return to caller
	 mov	%t_kstack, %sp		! jump onto new stack

trap_setup_kernel_spill:
	ld	[%curptr + TI_UWINMASK], %g1
	orcc	%g0, %g1, %g0
	bne	trap_setup_user_spill	! there are some user windows, yuck
	/* Spill from kernel, but only kernel windows, adjust
	 * %wim and go.
	 */
	 srl	%t_wim, 0x1, %g2	! begin computation of new %wim
tsetup_patch1:
	sll	%t_wim, 0x7, %t_wim	! patched on 7 window Sparcs
	or	%t_wim, %g2, %g2
tsetup_patch2:
	and	%g2, 0xff, %g2		! patched on 7 window Sparcs

	save	%g0, %g0, %g0

	/* Set new %wim value */
	wr	%g2, 0x0, %wim

	/* Save the kernel window onto the corresponding stack. */
	STORE_WINDOW(sp)

	restore	%g0, %g0, %g0

	jmpl	%t_retpc + 0x8, %g0	! return to caller
	 mov	%t_kstack, %sp		! and onto new kernel stack

#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ)

trap_setup_from_user:
	/* We can't use %curptr yet. */
	LOAD_CURRENT(t_kstack, t_twinmask)

	sethi	%hi(STACK_OFFSET), %t_twinmask
	or	%t_twinmask, %lo(STACK_OFFSET), %t_twinmask
	add	%t_kstack, %t_twinmask, %t_kstack

	mov	1, %t_twinmask
	sll	%t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr)

	/* Build pt_regs frame. */
	STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2)

#if 0
	/* If we're sure every task_struct is THREAD_SIZE aligned,
	   we can speed this up. */
	sethi	%hi(STACK_OFFSET), %curptr
	or	%curptr, %lo(STACK_OFFSET), %curptr
	sub	%t_kstack, %curptr, %curptr
#else
	sethi	%hi(~(THREAD_SIZE - 1)), %curptr
	and	%t_kstack, %curptr, %curptr
#endif

	/* Clear current_thread_info->w_saved */
	st	%g0, [%curptr + TI_W_SAVED]

	/* See if we are in the trap window. */
	andcc	%t_twinmask, %t_wim, %g0
	bne	trap_setup_user_spill		! yep we are
	 orn	%g0, %t_twinmask, %g1		! negate trap win mask into %g1

	/* Trap from user, but not into the invalid window.
	 * Calculate new umask.  The way this works is,
	 * any window from the %wim at trap time until
	 * the window right before the one we are in now,
	 * is a user window.  A diagram:
	 *
	 *      7 6 5 4 3 2 1 0    window number
	 *      ---------------
	 *        I     L T        mnemonic
	 *
	 * Window 'I' is the invalid window in our example,
	 * window 'L' is the window the user was in when
	 * the trap occurred, window T is the trap window
	 * we are in now.  So therefore, windows 5, 4 and
	 * 3 are user windows.  The following sequence
	 * computes the user winmask to represent this.
	 */
	subcc	%t_wim, %t_twinmask, %g2
	bneg,a	1f
	 sub	%g2, 0x1, %g2
1:
	andn	%g2, %t_twinmask, %g2
tsetup_patch3:
	and	%g2, 0xff, %g2			! patched on 7win Sparcs
	st	%g2, [%curptr + TI_UWINMASK]	! store new umask

	jmpl	%t_retpc + 0x8, %g0		! return to caller
	 mov	%t_kstack, %sp			! and onto kernel stack

trap_setup_user_spill:
	/* A spill occurred from either kernel or user mode
	 * and there exist some user windows to deal with.
	 * A mask of the currently valid user windows
	 * is in %g1 upon entry to here.
	 */

tsetup_patch4:
	and	%g1, 0xff, %g1		! patched on 7win Sparcs, mask
	srl	%t_wim, 0x1, %g2	! compute new %wim
tsetup_patch5:
	sll	%t_wim, 0x7, %t_wim	! patched on 7win Sparcs
	or	%t_wim, %g2, %g2	! %g2 is new %wim
tsetup_patch6:
	and	%g2, 0xff, %g2		! patched on 7win Sparcs
	andn	%g1, %g2, %g1		! clear this bit in %g1
	st	%g1, [%curptr + TI_UWINMASK]

	save	%g0, %g0, %g0

	wr	%g2, 0x0, %wim

	/* Call MMU-architecture dependent stack checking
	 * routine.
	 */
	b	tsetup_srmmu_stackchk
	 andcc	%sp, 0x7, %g0

	/* Architecture specific stack checking routines.  When either
	 * of these routines are called, the globals are free to use
	 * as they have been safely stashed on the new kernel stack
	 * pointer.  Thus the definition below for simplicity.
	 */
#define glob_tmp     g1

	.globl	tsetup_srmmu_stackchk
tsetup_srmmu_stackchk:
	/* Check results of callers andcc %sp, 0x7, %g0 */
	bne	trap_setup_user_stack_is_bolixed
	 sethi   %hi(PAGE_OFFSET), %glob_tmp

	cmp	%glob_tmp, %sp
	bleu,a	1f
LEON_PI( lda	[%g0] ASI_LEON_MMUREGS, %glob_tmp)	! read MMU control
SUN_PI_( lda	[%g0] ASI_M_MMUREGS, %glob_tmp)		! read MMU control

trap_setup_user_stack_is_bolixed:
	/* From user/kernel into invalid window w/bad user
	 * stack. Save bad user stack, and return to caller.
	 */
	SAVE_BOLIXED_USER_STACK(curptr, g3)
	restore	%g0, %g0, %g0

	jmpl	%t_retpc + 0x8, %g0
	 mov	%t_kstack, %sp

1:
	/* Clear the fault status and turn on the no_fault bit. */
	or	%glob_tmp, 0x2, %glob_tmp		! or in no_fault bit
LEON_PI(sta	%glob_tmp, [%g0] ASI_LEON_MMUREGS)		! set it
SUN_PI_(sta	%glob_tmp, [%g0] ASI_M_MMUREGS)		! set it

	/* Dump the registers and cross fingers. */
	STORE_WINDOW(sp)

	/* Clear the no_fault bit and check the status. */
	andn	%glob_tmp, 0x2, %glob_tmp
LEON_PI(sta	%glob_tmp, [%g0] ASI_LEON_MMUREGS)
SUN_PI_(sta	%glob_tmp, [%g0] ASI_M_MMUREGS)

	mov	AC_M_SFAR, %glob_tmp
LEON_PI(lda	[%glob_tmp] ASI_LEON_MMUREGS, %g0)
SUN_PI_(lda	[%glob_tmp] ASI_M_MMUREGS, %g0)

	mov	AC_M_SFSR, %glob_tmp
LEON_PI(lda	[%glob_tmp] ASI_LEON_MMUREGS, %glob_tmp)! save away status of winstore
SUN_PI_(lda	[%glob_tmp] ASI_M_MMUREGS, %glob_tmp)	! save away status of winstore

	andcc	%glob_tmp, 0x2, %g0			! did we fault?
	bne	trap_setup_user_stack_is_bolixed	! failure
	 nop

	restore %g0, %g0, %g0

	jmpl	%t_retpc + 0x8, %g0
	 mov	%t_kstack, %sp