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1/*
2 * Copyright (C) 1999, 2000, 2002 Niibe Yutaka
3 * Copyright (C) 2003 - 2008 Paul Mundt
4 *
5 * This file is subject to the terms and conditions of the GNU General Public
6 * License. See the file "COPYING" in the main directory of this archive
7 * for more details.
8 *
9 */
10
11! NOTE:
12! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
13! to be jumped is too far, but it causes illegal slot exception.
14
15/*
16 * entry.S contains the system-call and fault low-level handling routines.
17 * This also contains the timer-interrupt handler, as well as all interrupts
18 * and faults that can result in a task-switch.
19 *
20 * NOTE: This code handles signal-recognition, which happens every time
21 * after a timer-interrupt and after each system call.
22 *
23 * NOTE: This code uses a convention that instructions in the delay slot
24 * of a transfer-control instruction are indented by an extra space, thus:
25 *
26 * jmp @k0 ! control-transfer instruction
27 * ldc k1, ssr ! delay slot
28 *
29 * Stack layout in 'ret_from_syscall':
30 * ptrace needs to have all regs on the stack.
31 * if the order here is changed, it needs to be
32 * updated in ptrace.c and ptrace.h
33 *
34 * r0
35 * ...
36 * r15 = stack pointer
37 * spc
38 * pr
39 * ssr
40 * gbr
41 * mach
42 * macl
43 * syscall #
44 *
45 */
46#include <asm/dwarf.h>
47
48#if defined(CONFIG_PREEMPT)
49# define preempt_stop() cli ; TRACE_IRQS_OFF
50#else
51# define preempt_stop()
52# define resume_kernel __restore_all
53#endif
54
55
56 .align 2
57ENTRY(exception_error)
58 !
59 TRACE_IRQS_ON
60 sti
61 mov.l 1f, r0
62 jmp @r0
63 nop
64
65 .align 2
661: .long do_exception_error
67
68 .align 2
69ret_from_exception:
70 CFI_STARTPROC simple
71 CFI_DEF_CFA r14, 0
72 CFI_REL_OFFSET 17, 64
73 CFI_REL_OFFSET 15, 60
74 CFI_REL_OFFSET 14, 56
75 CFI_REL_OFFSET 13, 52
76 CFI_REL_OFFSET 12, 48
77 CFI_REL_OFFSET 11, 44
78 CFI_REL_OFFSET 10, 40
79 CFI_REL_OFFSET 9, 36
80 CFI_REL_OFFSET 8, 32
81 preempt_stop()
82ENTRY(ret_from_irq)
83 !
84 mov #OFF_SR, r0
85 mov.l @(r0,r15), r0 ! get status register
86 shll r0
87 shll r0 ! kernel space?
88 get_current_thread_info r8, r0
89 bt resume_kernel ! Yes, it's from kernel, go back soon
90
91#ifdef CONFIG_PREEMPT
92 bra resume_userspace
93 nop
94ENTRY(resume_kernel)
95 cli
96 TRACE_IRQS_OFF
97 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count
98 tst r0, r0
99 bf noresched
100need_resched:
101 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
102 tst #_TIF_NEED_RESCHED, r0 ! need_resched set?
103 bt noresched
104
105 mov #OFF_SR, r0
106 mov.l @(r0,r15), r0 ! get status register
107 shlr r0
108 and #(0xf0>>1), r0 ! interrupts off (exception path)?
109 cmp/eq #(0xf0>>1), r0
110 bt noresched
111 mov.l 3f, r0
112 jsr @r0 ! call preempt_schedule_irq
113 nop
114 bra need_resched
115 nop
116
117noresched:
118 bra __restore_all
119 nop
120
121 .align 2
1221: .long PREEMPT_ACTIVE
1232: .long schedule
1243: .long preempt_schedule_irq
125#endif
126
127ENTRY(resume_userspace)
128 ! r8: current_thread_info
129 cli
130 TRACE_IRQS_OFF
131 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
132 tst #(_TIF_WORK_MASK & 0xff), r0
133 bt/s __restore_all
134 tst #_TIF_NEED_RESCHED, r0
135
136 .align 2
137work_pending:
138 ! r0: current_thread_info->flags
139 ! r8: current_thread_info
140 ! t: result of "tst #_TIF_NEED_RESCHED, r0"
141 bf/s work_resched
142 tst #_TIF_SIGPENDING, r0
143work_notifysig:
144 bt/s __restore_all
145 mov r15, r4
146 mov r12, r5 ! set arg1(save_r0)
147 mov r0, r6
148 sti
149 mov.l 2f, r1
150 mov.l 3f, r0
151 jmp @r1
152 lds r0, pr
153work_resched:
154 mov.l 1f, r1
155 jsr @r1 ! schedule
156 nop
157 cli
158 TRACE_IRQS_OFF
159 !
160 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
161 tst #(_TIF_WORK_MASK & 0xff), r0
162 bt __restore_all
163 bra work_pending
164 tst #_TIF_NEED_RESCHED, r0
165
166 .align 2
1671: .long schedule
1682: .long do_notify_resume
1693: .long resume_userspace
170
171 .align 2
172syscall_exit_work:
173 ! r0: current_thread_info->flags
174 ! r8: current_thread_info
175 tst #(_TIF_WORK_SYSCALL_MASK & 0xff), r0
176 bt/s work_pending
177 tst #_TIF_NEED_RESCHED, r0
178 TRACE_IRQS_ON
179 sti
180 mov r15, r4
181 mov.l 8f, r0 ! do_syscall_trace_leave
182 jsr @r0
183 nop
184 bra resume_userspace
185 nop
186
187 .align 2
188syscall_trace_entry:
189 ! Yes it is traced.
190 mov r15, r4
191 mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies
192 jsr @r11 ! superior (will chomp R[0-7])
193 nop
194 mov.l r0, @(OFF_R0,r15) ! Save return value
195 ! Reload R0-R4 from kernel stack, where the
196 ! parent may have modified them using
197 ! ptrace(POKEUSR). (Note that R0-R2 are
198 ! used by the system call handler directly
199 ! from the kernel stack anyway, so don't need
200 ! to be reloaded here.) This allows the parent
201 ! to rewrite system calls and args on the fly.
202 mov.l @(OFF_R4,r15), r4 ! arg0
203 mov.l @(OFF_R5,r15), r5
204 mov.l @(OFF_R6,r15), r6
205 mov.l @(OFF_R7,r15), r7 ! arg3
206 mov.l @(OFF_R3,r15), r3 ! syscall_nr
207 !
208 mov.l 2f, r10 ! Number of syscalls
209 cmp/hs r10, r3
210 bf syscall_call
211 mov #-ENOSYS, r0
212 bra syscall_exit
213 mov.l r0, @(OFF_R0,r15) ! Return value
214
215__restore_all:
216 mov #OFF_SR, r0
217 mov.l @(r0,r15), r0 ! get status register
218
219 shlr2 r0
220 and #0x3c, r0
221 cmp/eq #0x3c, r0
222 bt 1f
223 TRACE_IRQS_ON
224 bra 2f
225 nop
2261:
227 TRACE_IRQS_OFF
2282:
229 mov.l 3f, r0
230 jmp @r0
231 nop
232
233 .align 2
2343: .long restore_all
235
236 .align 2
237syscall_badsys: ! Bad syscall number
238 get_current_thread_info r8, r0
239 mov #-ENOSYS, r0
240 bra resume_userspace
241 mov.l r0, @(OFF_R0,r15) ! Return value
242
243/*
244 * The main debug trap handler.
245 *
246 * r8=TRA (not the trap number!)
247 *
248 * Note: This assumes that the trapa value is left in its original
249 * form (without the shlr2 shift) so the calculation for the jump
250 * call table offset remains a simple in place mask.
251 */
252debug_trap:
253 mov r8, r0
254 and #(0xf << 2), r0
255 mov.l 1f, r8
256 add r0, r8
257 mov.l @r8, r8
258 jsr @r8
259 nop
260 bra __restore_all
261 nop
262 CFI_ENDPROC
263
264 .align 2
2651: .long debug_trap_table
266
267/*
268 * Syscall interface:
269 *
270 * Syscall #: R3
271 * Arguments #0 to #3: R4--R7
272 * Arguments #4 to #6: R0, R1, R2
273 * TRA: (number of arguments + ABI revision) x 4
274 *
275 * This code also handles delegating other traps to the BIOS/gdb stub
276 * according to:
277 *
278 * Trap number
279 * (TRA>>2) Purpose
280 * -------- -------
281 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use).
282 * 0x10-0x1f general SH-3/4 syscall ABI.
283 * 0x20-0x2f syscall ABI for SH-2 parts.
284 * 0x30-0x3f debug traps used by the kernel.
285 * 0x40-0xff Not supported by all parts, so left unhandled.
286 *
287 * Note: When we're first called, the TRA value must be shifted
288 * right 2 bits in order to get the value that was used as the "trapa"
289 * argument.
290 */
291
292 .align 2
293 .globl ret_from_fork
294ret_from_fork:
295 mov.l 1f, r8
296 jsr @r8
297 mov r0, r4
298 bra syscall_exit
299 nop
300 .align 2
3011: .long schedule_tail
302
303/*
304 * The poorly named main trapa decode and dispatch routine, for
305 * system calls and debug traps through their respective jump tables.
306 */
307ENTRY(system_call)
308 setup_frame_reg
309#if !defined(CONFIG_CPU_SH2)
310 mov.l 1f, r9
311 mov.l @r9, r8 ! Read from TRA (Trap Address) Register
312#endif
313
314 mov #OFF_TRA, r10
315 add r15, r10
316 mov.l r8, @r10 ! set TRA value to tra
317
318 /*
319 * Check the trap type
320 */
321 mov #((0x20 << 2) - 1), r9
322 cmp/hi r9, r8
323 bt/s debug_trap ! it's a debug trap..
324 nop
325
326 TRACE_IRQS_ON
327 sti
328
329 !
330 get_current_thread_info r8, r10
331 mov.l @(TI_FLAGS,r8), r8
332 mov #(_TIF_WORK_SYSCALL_MASK & 0xff), r10
333 mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9
334 tst r10, r8
335 shll8 r9
336 bf syscall_trace_entry
337 tst r9, r8
338 bf syscall_trace_entry
339 !
340 mov.l 2f, r8 ! Number of syscalls
341 cmp/hs r8, r3
342 bt syscall_badsys
343 !
344syscall_call:
345 shll2 r3 ! x4
346 mov.l 3f, r8 ! Load the address of sys_call_table
347 add r8, r3
348 mov.l @r3, r8
349 jsr @r8 ! jump to specific syscall handler
350 nop
351 mov.l @(OFF_R0,r15), r12 ! save r0
352 mov.l r0, @(OFF_R0,r15) ! save the return value
353 !
354syscall_exit:
355 cli
356 TRACE_IRQS_OFF
357 !
358 get_current_thread_info r8, r0
359 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
360 tst #(_TIF_ALLWORK_MASK & 0xff), r0
361 mov #(_TIF_ALLWORK_MASK >> 8), r1
362 bf syscall_exit_work
363 shlr8 r0
364 tst r0, r1
365 bf syscall_exit_work
366 bra __restore_all
367 nop
368 .align 2
369#if !defined(CONFIG_CPU_SH2)
3701: .long TRA
371#endif
3722: .long NR_syscalls
3733: .long sys_call_table
3747: .long do_syscall_trace_enter
3758: .long do_syscall_trace_leave
1/* SPDX-License-Identifier: GPL-2.0
2 *
3 * Copyright (C) 1999, 2000, 2002 Niibe Yutaka
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 and bra, when the address
9! to be jumped is too far, but it causes illegal slot exception.
10
11/*
12 * entry.S contains the system-call and fault low-level handling routines.
13 * This also contains the timer-interrupt handler, as well as all interrupts
14 * and faults that can result in a task-switch.
15 *
16 * NOTE: This code handles signal-recognition, which happens every time
17 * after a timer-interrupt and after each system call.
18 *
19 * NOTE: This code uses a convention that instructions in the delay slot
20 * of a transfer-control instruction are indented by an extra space, thus:
21 *
22 * jmp @k0 ! control-transfer instruction
23 * ldc k1, ssr ! delay slot
24 *
25 * Stack layout in 'ret_from_syscall':
26 * ptrace needs to have all regs on the stack.
27 * if the order here is changed, it needs to be
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_IRQS_OFF
46#else
47# define preempt_stop()
48# define resume_kernel __restore_all
49#endif
50
51
52 .align 2
53ENTRY(exception_error)
54 !
55 TRACE_IRQS_ON
56 sti
57 mov.l 1f, r0
58 jmp @r0
59 nop
60
61 .align 2
621: .long do_exception_error
63
64 .align 2
65ret_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()
78ENTRY(ret_from_irq)
79 !
80 mov #OFF_SR, r0
81 mov.l @(r0,r15), r0 ! get status register
82 shll r0
83 shll r0 ! kernel space?
84 get_current_thread_info r8, r0
85 bt resume_kernel ! Yes, it's from kernel, go back soon
86
87#ifdef CONFIG_PREEMPTION
88 bra resume_userspace
89 nop
90ENTRY(resume_kernel)
91 cli
92 TRACE_IRQS_OFF
93 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count
94 tst r0, r0
95 bf noresched
96need_resched:
97 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
98 tst #_TIF_NEED_RESCHED, r0 ! need_resched set?
99 bt noresched
100
101 mov #OFF_SR, r0
102 mov.l @(r0,r15), r0 ! get status register
103 shlr r0
104 and #(0xf0>>1), r0 ! interrupts off (exception path)?
105 cmp/eq #(0xf0>>1), r0
106 bt noresched
107 mov.l 1f, r0
108 jsr @r0 ! call preempt_schedule_irq
109 nop
110 bra need_resched
111 nop
112
113noresched:
114 bra __restore_all
115 nop
116
117 .align 2
1181: .long preempt_schedule_irq
119#endif
120
121ENTRY(resume_userspace)
122 ! r8: current_thread_info
123 cli
124 TRACE_IRQS_OFF
125 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
126 tst #(_TIF_WORK_MASK & 0xff), r0
127 bt/s __restore_all
128 tst #_TIF_NEED_RESCHED, r0
129
130 .align 2
131work_pending:
132 ! r0: current_thread_info->flags
133 ! r8: current_thread_info
134 ! t: result of "tst #_TIF_NEED_RESCHED, r0"
135 bf/s work_resched
136 tst #(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME), r0
137work_notifysig:
138 bt/s __restore_all
139 mov r15, r4
140 mov r12, r5 ! set arg1(save_r0)
141 mov r0, r6
142 sti
143 mov.l 2f, r1
144 mov.l 3f, r0
145 jmp @r1
146 lds r0, pr
147work_resched:
148 mov.l 1f, r1
149 jsr @r1 ! schedule
150 nop
151 cli
152 TRACE_IRQS_OFF
153 !
154 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
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
1611: .long schedule
1622: .long do_notify_resume
1633: .long resume_userspace
164
165 .align 2
166syscall_exit_work:
167 ! r0: current_thread_info->flags
168 ! r8: current_thread_info
169 tst #(_TIF_WORK_SYSCALL_MASK & 0xff), r0
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_syscall_trace_leave
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 register
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
1921:
193 TRACE_IRQS_OFF
1942:
195 mov.l 3f, r0
196 jmp @r0
197 nop
198
199 .align 2
2003: .long restore_all
201
202 .align 2
203syscall_badsys: ! Bad syscall number
204 get_current_thread_info r8, r0
205 mov #-ENOSYS, r0
206 bra resume_userspace
207 mov.l r0, @(OFF_R0,r15) ! Return value
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 left in its original
215 * form (without the shlr2 shift) so the calculation for the jump
216 * call table offset remains a simple in place mask.
217 */
218debug_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
2311: .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 (not in general use).
244 * 0x10-0x1f general SH-3/4 syscall ABI.
245 * 0x1f unified SH-2/3/4 syscall ABI (preferred).
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 left unhandled.
249 *
250 * For making system calls, any trap number in the range for the
251 * given cpu model may be used, but the unified trap number 0x1f is
252 * preferred for compatibility with all models.
253 *
254 * The low bits of the trap number were once documented as matching
255 * the number of arguments, but they were never actually used as such
256 * by the kernel. SH-2 originally used its own separate trap range
257 * because several hardware exceptions fell in the range used for the
258 * SH-3/4 syscall ABI.
259 *
260 * This code also handles delegating other traps to the BIOS/gdb stub.
261 *
262 * Note: When we're first called, the TRA value must be shifted
263 * right 2 bits in order to get the value that was used as the "trapa"
264 * argument.
265 */
266
267 .align 2
268 .globl ret_from_fork
269ret_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
278ret_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
2891: .long schedule_tail
290
291/*
292 * The poorly named main trapa decode and dispatch routine, for
293 * system calls and debug traps through their respective jump tables.
294 */
295ENTRY(system_call)
296 setup_frame_reg
297#if !defined(CONFIG_CPU_SH2)
298 mov.l 1f, r9
299 mov.l @r9, r8 ! Read from TRA (Trap Address) Register
300#endif
301
302 mov #OFF_TRA, r10
303 add r15, r10
304 mov.l r8, @r10 ! set TRA value to tra
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 a debug trap..
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 & 0xff), r10
321 mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9
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 ! Number of syscalls
329 cmp/hs r8, r3
330 bt syscall_badsys
331 !
332syscall_call:
333 shll2 r3 ! x4
334 mov.l 3f, r8 ! Load the address of sys_call_table
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 specific syscall handler
344 nop
345 add #12, r15
346 mov.l @(OFF_R0,r15), r12 ! save r0
347 mov.l r0, @(OFF_R0,r15) ! save the return value
348 !
349syscall_exit:
350 cli
351 TRACE_IRQS_OFF
352 !
353 get_current_thread_info r8, r0
354 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
355 tst #(_TIF_ALLWORK_MASK & 0xff), r0
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
365syscall_trace_entry:
366 ! Yes it is traced.
367 mov r15, r4
368 mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies
369 jsr @r11 ! superior (will chomp R[0-7])
370 nop
371 cmp/eq #-1, r0
372 bt syscall_exit
373 ! Reload R0-R4 from kernel stack, where the
374 ! parent may have modified them using
375 ! ptrace(POKEUSR). (Note that R0-R2 are
376 ! reloaded from the kernel stack by syscall_call
377 ! below, so don't need to be reloaded here.)
378 ! This allows the parent to rewrite system calls
379 ! and args on the fly.
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_nr
385 !
386 mov.l 6f, r10 ! Number of syscalls
387 cmp/hs r10, r3
388 bf syscall_call
389 mov #-ENOSYS, r0
390 bra syscall_exit
391 mov.l r0, @(OFF_R0,r15) ! Return value
392
393 .align 2
394#if !defined(CONFIG_CPU_SH2)
3951: .long TRA
396#endif
3976: .long NR_syscalls
3983: .long sys_call_table
3997: .long do_syscall_trace_enter
4008: .long do_syscall_trace_leave