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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
4 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
5 *
6 * Vineetg: March 2009 (Supporting 2 levels of Interrupts)
7 * Stack switching code can no longer reliably rely on the fact that
8 * if we are NOT in user mode, stack is switched to kernel mode.
9 * e.g. L2 IRQ interrupted a L1 ISR which had not yet completed
10 * its prologue including stack switching from user mode
11 *
12 * Vineetg: Aug 28th 2008: Bug #94984
13 * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap
14 * Normally CPU does this automatically, however when doing FAKE rtie,
15 * we also need to explicitly do this. The problem in macros
16 * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit
17 * was being "CLEARED" rather then "SET". Actually "SET" clears ZOL context
18 *
19 * Vineetg: May 5th 2008
20 * -Modified CALLEE_REG save/restore macros to handle the fact that
21 * r25 contains the kernel current task ptr
22 * - Defined Stack Switching Macro to be reused in all intr/excp hdlrs
23 * - Shaved off 11 instructions from RESTORE_ALL_INT1 by using the
24 * address Write back load ld.ab instead of separate ld/add instn
25 *
26 * Amit Bhor, Sameer Dhavale: Codito Technologies 2004
27 */
28
29#ifndef __ASM_ARC_ENTRY_COMPACT_H
30#define __ASM_ARC_ENTRY_COMPACT_H
31
32#include <asm/asm-offsets.h>
33#include <asm/irqflags-compact.h>
34#include <asm/thread_info.h> /* For THREAD_SIZE */
35
36/* Note on the LD/ST addr modes with addr reg wback
37 *
38 * LD.a same as LD.aw
39 *
40 * LD.a reg1, [reg2, x] => Pre Incr
41 * Eff Addr for load = [reg2 + x]
42 *
43 * LD.ab reg1, [reg2, x] => Post Incr
44 * Eff Addr for load = [reg2]
45 */
46
47.macro PUSHAX aux
48 lr r9, [\aux]
49 push r9
50.endm
51
52.macro POPAX aux
53 pop r9
54 sr r9, [\aux]
55.endm
56
57.macro SAVE_R0_TO_R12
58 push r0
59 push r1
60 push r2
61 push r3
62 push r4
63 push r5
64 push r6
65 push r7
66 push r8
67 push r9
68 push r10
69 push r11
70 push r12
71.endm
72
73.macro RESTORE_R12_TO_R0
74 pop r12
75 pop r11
76 pop r10
77 pop r9
78 pop r8
79 pop r7
80 pop r6
81 pop r5
82 pop r4
83 pop r3
84 pop r2
85 pop r1
86 pop r0
87.endm
88
89.macro SAVE_ABI_CALLEE_REGS
90 push r13
91 push r14
92 push r15
93 push r16
94 push r17
95 push r18
96 push r19
97 push r20
98 push r21
99 push r22
100 push r23
101 push r24
102 push r25
103.endm
104
105.macro RESTORE_ABI_CALLEE_REGS
106 pop r25
107 pop r24
108 pop r23
109 pop r22
110 pop r21
111 pop r20
112 pop r19
113 pop r18
114 pop r17
115 pop r16
116 pop r15
117 pop r14
118 pop r13
119.endm
120
121/*--------------------------------------------------------------
122 * Switch to Kernel Mode stack if SP points to User Mode stack
123 *
124 * Entry : r9 contains pre-IRQ/exception/trap status32
125 * Exit : SP set to K mode stack
126 * SP at the time of entry (K/U) saved @ pt_regs->sp
127 * Clobbers: r9
128 *-------------------------------------------------------------*/
129
130.macro SWITCH_TO_KERNEL_STK
131
132 /* User Mode when this happened ? Yes: Proceed to switch stack */
133 bbit1 r9, STATUS_U_BIT, 88f
134
135 /* OK we were already in kernel mode when this event happened, thus can
136 * assume SP is kernel mode SP. _NO_ need to do any stack switching
137 */
138
139#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
140 /* However....
141 * If Level 2 Interrupts enabled, we may end up with a corner case:
142 * 1. User Task executing
143 * 2. L1 IRQ taken, ISR starts (CPU auto-switched to KERNEL mode)
144 * 3. But before it could switch SP from USER to KERNEL stack
145 * a L2 IRQ "Interrupts" L1
146 * That way although L2 IRQ happened in Kernel mode, stack is still
147 * not switched.
148 * To handle this, we may need to switch stack even if in kernel mode
149 * provided SP has values in range of USER mode stack ( < 0x7000_0000 )
150 */
151 brlo sp, VMALLOC_START, 88f
152
153 /* TODO: vineetg:
154 * We need to be a bit more cautious here. What if a kernel bug in
155 * L1 ISR, caused SP to go whaco (some small value which looks like
156 * USER stk) and then we take L2 ISR.
157 * Above brlo alone would treat it as a valid L1-L2 scenario
158 * instead of shouting around
159 * The only feasible way is to make sure this L2 happened in
160 * L1 prelogue ONLY i.e. ilink2 is less than a pre-set marker in
161 * L1 ISR before it switches stack
162 */
163
164#endif
165
166 /*------Intr/Ecxp happened in kernel mode, SP already setup ------ */
167 /* save it nevertheless @ pt_regs->sp for uniformity */
168
169 b.d 66f
170 st sp, [sp, PT_sp - SZ_PT_REGS]
171
17288: /*------Intr/Ecxp happened in user mode, "switch" stack ------ */
173
174 GET_CURR_TASK_ON_CPU r9
175
176 /* With current tsk in r9, get its kernel mode stack base */
177 GET_TSK_STACK_BASE r9, r9
178
179 /* save U mode SP @ pt_regs->sp */
180 st sp, [r9, PT_sp - SZ_PT_REGS]
181
182 /* final SP switch */
183 mov sp, r9
18466:
185.endm
186
187/*------------------------------------------------------------
188 * "FAKE" a rtie to return from CPU Exception context
189 * This is to re-enable Exceptions within exception
190 * Look at EV_ProtV to see how this is actually used
191 *-------------------------------------------------------------*/
192
193.macro FAKE_RET_FROM_EXCPN
194
195 lr r9, [status32]
196 bclr r9, r9, STATUS_AE_BIT
197 or r9, r9, (STATUS_E1_MASK|STATUS_E2_MASK)
198 sr r9, [erstatus]
199 mov r9, 55f
200 sr r9, [eret]
201 rtie
20255:
203.endm
204
205/*--------------------------------------------------------------
206 * For early Exception/ISR Prologue, a core reg is temporarily needed to
207 * code the rest of prolog (stack switching). This is done by stashing
208 * it to memory (non-SMP case) or SCRATCH0 Aux Reg (SMP).
209 *
210 * Before saving the full regfile - this reg is restored back, only
211 * to be saved again on kernel mode stack, as part of pt_regs.
212 *-------------------------------------------------------------*/
213.macro PROLOG_FREEUP_REG reg, mem
214 st \reg, [\mem]
215.endm
216
217.macro PROLOG_RESTORE_REG reg, mem
218 ld \reg, [\mem]
219.endm
220
221/*--------------------------------------------------------------
222 * Exception Entry prologue
223 * -Switches stack to K mode (if not already)
224 * -Saves the register file
225 *
226 * After this it is safe to call the "C" handlers
227 *-------------------------------------------------------------*/
228.macro EXCEPTION_PROLOGUE_KEEP_AE
229
230 /* Need at least 1 reg to code the early exception prologue */
231 PROLOG_FREEUP_REG r9, @ex_saved_reg1
232
233 /* U/K mode at time of exception (stack not switched if already K) */
234 lr r9, [erstatus]
235
236 /* ARC700 doesn't provide auto-stack switching */
237 SWITCH_TO_KERNEL_STK
238
239 st.a r0, [sp, -8] /* orig_r0 needed for syscall (skip ECR slot) */
240 sub sp, sp, 4 /* skip pt_regs->sp, already saved above */
241
242 /* Restore r9 used to code the early prologue */
243 PROLOG_RESTORE_REG r9, @ex_saved_reg1
244
245 /* now we are ready to save the regfile */
246 SAVE_R0_TO_R12
247 PUSH gp
248 PUSH fp
249 PUSH blink
250 PUSHAX eret
251 PUSHAX erstatus
252 PUSH lp_count
253 PUSHAX lp_end
254 PUSHAX lp_start
255 PUSHAX erbta
256
257 lr r10, [ecr]
258 st r10, [sp, PT_event]
259
260#ifdef CONFIG_ARC_CURR_IN_REG
261 /* gp already saved on stack: now load with "current" */
262 GET_CURR_TASK_ON_CPU gp
263#endif
264 ; OUTPUT: r10 has ECR expected by EV_Trap
265.endm
266
267.macro EXCEPTION_PROLOGUE
268
269 EXCEPTION_PROLOGUE_KEEP_AE ; return ECR in r10
270
271 lr r0, [efa]
272 mov r1, sp
273
274 FAKE_RET_FROM_EXCPN ; clobbers r9
275.endm
276
277/*--------------------------------------------------------------
278 * Restore all registers used by system call or Exceptions
279 * SP should always be pointing to the next free stack element
280 * when entering this macro.
281 *
282 * NOTE:
283 *
284 * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg
285 * for memory load operations. If used in that way interrupts are deferred
286 * by hardware and that is not good.
287 *-------------------------------------------------------------*/
288.macro EXCEPTION_EPILOGUE
289
290 POPAX erbta
291 POPAX lp_start
292 POPAX lp_end
293
294 POP r9
295 mov lp_count, r9 ;LD to lp_count is not allowed
296
297 POPAX erstatus
298 POPAX eret
299 POP blink
300 POP fp
301 POP gp
302 RESTORE_R12_TO_R0
303
304 ld sp, [sp] /* restore original sp */
305 /* orig_r0, ECR skipped automatically */
306.endm
307
308/* Dummy ECR values for Interrupts */
309#define event_IRQ1 0x0031abcd
310#define event_IRQ2 0x0032abcd
311
312.macro INTERRUPT_PROLOGUE LVL
313
314 /* free up r9 as scratchpad */
315 PROLOG_FREEUP_REG r9, @int\LVL\()_saved_reg
316
317 /* Which mode (user/kernel) was the system in when intr occurred */
318 lr r9, [status32_l\LVL\()]
319
320 SWITCH_TO_KERNEL_STK
321
322
323 st.a 0x003\LVL\()abcd, [sp, -4] /* Dummy ECR */
324 sub sp, sp, 8 /* skip orig_r0 (not needed)
325 skip pt_regs->sp, already saved above */
326
327 /* Restore r9 used to code the early prologue */
328 PROLOG_RESTORE_REG r9, @int\LVL\()_saved_reg
329
330 SAVE_R0_TO_R12
331 PUSH gp
332 PUSH fp
333 PUSH blink
334 PUSH ilink\LVL\()
335 PUSHAX status32_l\LVL\()
336 PUSH lp_count
337 PUSHAX lp_end
338 PUSHAX lp_start
339 PUSHAX bta_l\LVL\()
340
341#ifdef CONFIG_ARC_CURR_IN_REG
342 /* gp already saved on stack: now load with "current" */
343 GET_CURR_TASK_ON_CPU gp
344#endif
345.endm
346
347/*--------------------------------------------------------------
348 * Restore all registers used by interrupt handlers.
349 *
350 * NOTE:
351 *
352 * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg
353 * for memory load operations. If used in that way interrupts are deferred
354 * by hardware and that is not good.
355 *-------------------------------------------------------------*/
356.macro INTERRUPT_EPILOGUE LVL
357
358 POPAX bta_l\LVL\()
359 POPAX lp_start
360 POPAX lp_end
361
362 POP r9
363 mov lp_count, r9 ;LD to lp_count is not allowed
364
365 POPAX status32_l\LVL\()
366 POP ilink\LVL\()
367 POP blink
368 POP fp
369 POP gp
370 RESTORE_R12_TO_R0
371
372 ld sp, [sp] /* restore original sp; orig_r0, ECR skipped implicitly */
373.endm
374
375/* Get thread_info of "current" tsk */
376.macro GET_CURR_THR_INFO_FROM_SP reg
377 bic \reg, sp, (THREAD_SIZE - 1)
378.endm
379
380/* Get CPU-ID of this core */
381.macro GET_CPU_ID reg
382 lr \reg, [identity]
383 lsr \reg, \reg, 8
384 bmsk \reg, \reg, 7
385.endm
386
387#endif /* __ASM_ARC_ENTRY_COMPACT_H */