1 /* SPDX-License-Identifier: GPL-2.0
2 *
3 * Copyright (C) 1999, 2000, 2002 Niibe Yuta
4 * Copyright (C) 2003 - 2008 Paul Mundt
5 */
6
7 ! NOTE:
8 ! GNU as (as of 2.9.1) changes bf/s into bt/s
9 ! to be jumped is too far, but it causes illeg
10
11 /*
12 * entry.S contains the system-call and fault
13 * This also contains the timer-interrupt hand
14 * and faults that can result in a task-switch
15 *
16 * NOTE: This code handles signal-recognition,
17 * after a timer-interrupt and after each syst
18 *
19 * NOTE: This code uses a convention that inst
20 * of a transfer-control instruction are inden
21 *
22 * jmp @k0 ! control-transfer
23 * ldc k1, ssr ! delay slot
24 *
25 * Stack layout in 'ret_from_syscall':
26 * ptrace needs to have all regs on the s
27 * if the order here is changed, it needs
28 * updated in ptrace.c and ptrace.h
29 *
30 * r0
31 * ...
32 * r15 = stack pointer
33 * spc
34 * pr
35 * ssr
36 * gbr
37 * mach
38 * macl
39 * syscall #
40 *
41 */
42 #include <asm/dwarf.h>
43
44 #if defined(CONFIG_PREEMPTION)
45 # define preempt_stop() cli ; TRACE_IR
46 #else
47 # define preempt_stop()
48 # define resume_kernel __restore_all
49 #endif
50
51
52 .align 2
53 ENTRY(exception_error)
54 !
55 TRACE_IRQS_ON
56 sti
57 mov.l 1f, r0
58 jmp @r0
59 nop
60
61 .align 2
62 1: .long do_exception_error
63
64 .align 2
65 ret_from_exception:
66 CFI_STARTPROC simple
67 CFI_DEF_CFA r14, 0
68 CFI_REL_OFFSET 17, 64
69 CFI_REL_OFFSET 15, 60
70 CFI_REL_OFFSET 14, 56
71 CFI_REL_OFFSET 13, 52
72 CFI_REL_OFFSET 12, 48
73 CFI_REL_OFFSET 11, 44
74 CFI_REL_OFFSET 10, 40
75 CFI_REL_OFFSET 9, 36
76 CFI_REL_OFFSET 8, 32
77 preempt_stop()
78 ENTRY(ret_from_irq)
79 !
80 mov #OFF_SR, r0
81 mov.l @(r0,r15), r0 ! get status r
82 shll r0
83 shll r0 ! kernel space
84 get_current_thread_info r8, r0
85 bt resume_kernel ! Yes, it's fr
86
87 #ifdef CONFIG_PREEMPTION
88 bra resume_userspace
89 nop
90 ENTRY(resume_kernel)
91 cli
92 TRACE_IRQS_OFF
93 mov.l @(TI_PRE_COUNT,r8), r0 ! curr
94 tst r0, r0
95 bf noresched
96 need_resched:
97 mov.l @(TI_FLAGS,r8), r0 ! curr
98 tst #_TIF_NEED_RESCHED, r0 ! need
99 bt noresched
100
101 mov #OFF_SR, r0
102 mov.l @(r0,r15), r0 ! get
103 shlr r0
104 and #(0xf0>>1), r0 ! inte
105 cmp/eq #(0xf0>>1), r0
106 bt noresched
107 mov.l 1f, r0
108 jsr @r0 ! call
109 nop
110 bra need_resched
111 nop
112
113 noresched:
114 bra __restore_all
115 nop
116
117 .align 2
118 1: .long preempt_schedule_irq
119 #endif
120
121 ENTRY(resume_userspace)
122 ! r8: current_thread_info
123 cli
124 TRACE_IRQS_OFF
125 mov.l @(TI_FLAGS,r8), r0
126 tst #(_TIF_WORK_MASK & 0xff), r0
127 bt/s __restore_all
128 tst #_TIF_NEED_RESCHED, r0
129
130 .align 2
131 work_pending:
132 ! r0: current_thread_info->flags
133 ! r8: current_thread_info
134 ! t: result of "tst #_TIF_NEED_RES
135 bf/s work_resched
136 tst #(_TIF_SIGPENDING | _TIF_NOTIF
137 work_notifysig:
138 bt/s __restore_all
139 mov r15, r4
140 mov r12, r5 ! set arg1(sav
141 mov r0, r6
142 sti
143 mov.l 2f, r1
144 mov.l 3f, r0
145 jmp @r1
146 lds r0, pr
147 work_resched:
148 mov.l 1f, r1
149 jsr @r1
150 nop
151 cli
152 TRACE_IRQS_OFF
153 !
154 mov.l @(TI_FLAGS,r8), r0
155 tst #(_TIF_WORK_MASK & 0xff), r0
156 bt __restore_all
157 bra work_pending
158 tst #_TIF_NEED_RESCHED, r0
159
160 .align 2
161 1: .long schedule
162 2: .long do_notify_resume
163 3: .long resume_userspace
164
165 .align 2
166 syscall_exit_work:
167 ! r0: current_thread_info->flags
168 ! r8: current_thread_info
169 tst #(_TIF_WORK_SYSCALL_MASK & 0xf
170 bt/s work_pending
171 tst #_TIF_NEED_RESCHED, r0
172 TRACE_IRQS_ON
173 sti
174 mov r15, r4
175 mov.l 8f, r0 ! do_s
176 jsr @r0
177 nop
178 bra resume_userspace
179 nop
180
181 __restore_all:
182 mov #OFF_SR, r0
183 mov.l @(r0,r15), r0 ! get status r
184
185 shlr2 r0
186 and #0x3c, r0
187 cmp/eq #0x3c, r0
188 bt 1f
189 TRACE_IRQS_ON
190 bra 2f
191 nop
192 1:
193 TRACE_IRQS_OFF
194 2:
195 mov.l 3f, r0
196 jmp @r0
197 nop
198
199 .align 2
200 3: .long restore_all
201
202 .align 2
203 syscall_badsys: ! Bad syscall
204 get_current_thread_info r8, r0
205 mov #-ENOSYS, r0
206 bra resume_userspace
207 mov.l r0, @(OFF_R0,r15) ! Retu
208
209 /*
210 * The main debug trap handler.
211 *
212 * r8=TRA (not the trap number!)
213 *
214 * Note: This assumes that the trapa value is
215 * form (without the shlr2 shift) so the calcu
216 * call table offset remains a simple in place
217 */
218 debug_trap:
219 mov r8, r0
220 and #(0xf << 2), r0
221 mov.l 1f, r8
222 add r0, r8
223 mov.l @r8, r8
224 jsr @r8
225 nop
226 bra ret_from_exception
227 nop
228 CFI_ENDPROC
229
230 .align 2
231 1: .long debug_trap_table
232
233 /*
234 * Syscall interface:
235 *
236 * Syscall #: R3
237 * Arguments #0 to #3: R4--R7
238 * Arguments #4 to #6: R0, R1, R2
239 * TRA: See following table.
240 *
241 * (TRA>>2) Purpose
242 * -------- -------
243 * 0x00-0x0f original SH-3/4 syscall ABI (n
244 * 0x10-0x1f general SH-3/4 syscall ABI.
245 * 0x1f unified SH-2/3/4 syscall ABI (
246 * 0x20-0x2f original SH-2 syscall ABI.
247 * 0x30-0x3f debug traps used by the kernel
248 * 0x40-0xff Not supported by all parts, so
249 *
250 * For making system calls, any trap number in
251 * given cpu model may be used, but the unifie
252 * preferred for compatibility with all models
253 *
254 * The low bits of the trap number were once d
255 * the number of arguments, but they were neve
256 * by the kernel. SH-2 originally used its own
257 * because several hardware exceptions fell in
258 * SH-3/4 syscall ABI.
259 *
260 * This code also handles delegating other tra
261 *
262 * Note: When we're first called, the TRA valu
263 * right 2 bits in order to get the value that
264 * argument.
265 */
266
267 .align 2
268 .globl ret_from_fork
269 ret_from_fork:
270 mov.l 1f, r8
271 jsr @r8
272 mov r0, r4
273 bra syscall_exit
274 nop
275
276 .align 2
277 .globl ret_from_kernel_thread
278 ret_from_kernel_thread:
279 mov.l 1f, r8
280 jsr @r8
281 mov r0, r4
282 mov.l @(OFF_R5,r15), r5 ! fn
283 jsr @r5
284 mov.l @(OFF_R4,r15), r4 ! arg
285 bra syscall_exit
286 nop
287
288 .align 2
289 1: .long schedule_tail
290
291 /*
292 * The poorly named main trapa decode and disp
293 * system calls and debug traps through their
294 */
295 ENTRY(system_call)
296 setup_frame_reg
297 #if !defined(CONFIG_CPU_SH2)
298 mov.l 1f, r9
299 mov.l @r9, r8 ! Read from TR
300 #endif
301
302 mov #OFF_TRA, r10
303 add r15, r10
304 mov.l r8, @r10 ! set
305
306 /*
307 * Check the trap type
308 */
309 mov #((0x20 << 2) - 1), r9
310 cmp/hi r9, r8
311 bt/s debug_trap ! it's
312 nop
313
314 TRACE_IRQS_ON
315 sti
316
317 !
318 get_current_thread_info r8, r10
319 mov.l @(TI_FLAGS,r8), r8
320 mov #(_TIF_WORK_SYSCALL_MASK & 0xf
321 mov #(_TIF_WORK_SYSCALL_MASK >> 8)
322 tst r10, r8
323 shll8 r9
324 bf syscall_trace_entry
325 tst r9, r8
326 bf syscall_trace_entry
327 !
328 mov.l 6f, r8 ! Numb
329 cmp/hs r8, r3
330 bt syscall_badsys
331 !
332 syscall_call:
333 shll2 r3 ! x4
334 mov.l 3f, r8 ! Load the add
335 add r8, r3
336 mov.l @r3, r8
337 mov.l @(OFF_R2,r15), r2
338 mov.l @(OFF_R1,r15), r1
339 mov.l @(OFF_R0,r15), r0
340 mov.l r2, @-r15
341 mov.l r1, @-r15
342 mov.l r0, @-r15
343 jsr @r8 ! jump to spec
344 nop
345 add #12, r15
346 mov.l @(OFF_R0,r15), r12
347 mov.l r0, @(OFF_R0,r15)
348 !
349 syscall_exit:
350 cli
351 TRACE_IRQS_OFF
352 !
353 get_current_thread_info r8, r0
354 mov.l @(TI_FLAGS,r8), r0
355 tst #(_TIF_ALLWORK_MASK & 0xff), r
356 mov #(_TIF_ALLWORK_MASK >> 8), r1
357 bf syscall_exit_work
358 shlr8 r0
359 tst r0, r1
360 bf syscall_exit_work
361 bra __restore_all
362 nop
363
364 .align 2
365 syscall_trace_entry:
366 ! Yes it is trac
367 mov r15, r4
368 mov.l 7f, r11 ! Call do_sysc
369 jsr @r11 ! superior (wi
370 nop
371 cmp/eq #-1, r0
372 bt syscall_exit
373 ! Reload R0-R4 f
374 ! parent may hav
375 ! ptrace(POKEUSR
376 ! reloaded from
377 ! below, so don'
378 ! This allows th
379 ! and args on th
380 mov.l @(OFF_R4,r15), r4 ! arg0
381 mov.l @(OFF_R5,r15), r5
382 mov.l @(OFF_R6,r15), r6
383 mov.l @(OFF_R7,r15), r7 ! arg3
384 mov.l @(OFF_R3,r15), r3 ! syscall_
385 !
386 mov.l 6f, r10 ! Numb
387 cmp/hs r10, r3
388 bf syscall_call
389 mov #-ENOSYS, r0
390 bra syscall_exit
391 mov.l r0, @(OFF_R0,r15) ! Retu
392
393 .align 2
394 #if !defined(CONFIG_CPU_SH2)
395 1: .long TRA
396 #endif
397 6: .long NR_syscalls
398 3: .long sys_call_table
399 7: .long do_syscall_trace_enter
400 8: .long do_syscall_trace_leave
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