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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARCompact ISA
4 *
5 * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
6 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
7 *
8 * vineetg: May 2011
9 * -Userspace unaligned access emulation
10 *
11 * vineetg: Feb 2011 (ptrace low level code fixes)
12 * -traced syscall return code (r0) was not saved into pt_regs for restoring
13 * into user reg-file when traded task rets to user space.
14 * -syscalls needing arch-wrappers (mainly for passing sp as pt_regs)
15 * were not invoking post-syscall trace hook (jumping directly into
16 * ret_from_system_call)
17 *
18 * vineetg: Nov 2010:
19 * -Vector table jumps (@8 bytes) converted into branches (@4 bytes)
20 * -To maintain the slot size of 8 bytes/vector, added nop, which is
21 * not executed at runtime.
22 *
23 * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
24 * -do_signal()invoked upon TIF_RESTORE_SIGMASK as well
25 * -Wrappers for sys_{,rt_}sigsuspend() no longer needed as they don't
26 * need ptregs anymore
27 *
28 * Vineetg: Oct 2009
29 * -In a rare scenario, Process gets a Priv-V exception and gets scheduled
30 * out. Since we don't do FAKE RTIE for Priv-V, CPU exception state remains
31 * active (AE bit enabled). This causes a double fault for a subseq valid
32 * exception. Thus FAKE RTIE needed in low level Priv-Violation handler.
33 * Instr Error could also cause similar scenario, so same there as well.
34 *
35 * Vineetg: March 2009 (Supporting 2 levels of Interrupts)
36 *
37 * Vineetg: Aug 28th 2008: Bug #94984
38 * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap
39 * Normally CPU does this automatically, however when doing FAKE rtie,
40 * we need to explicitly do this. The problem in macros
41 * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit
42 * was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit,
43 * setting it and not clearing it clears ZOL context
44 *
45 * Vineetg: May 16th, 2008
46 * - r25 now contains the Current Task when in kernel
47 *
48 * Vineetg: Dec 22, 2007
49 * Minor Surgery of Low Level ISR to make it SMP safe
50 * - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR
51 * - _current_task is made an array of NR_CPUS
52 * - Access of _current_task wrapped inside a macro so that if hardware
53 * team agrees for a dedicated reg, no other code is touched
54 *
55 * Amit Bhor, Rahul Trivedi, Kanika Nema, Sameer Dhavale : Codito Tech 2004
56 */
57
58#include <linux/errno.h>
59#include <linux/linkage.h> /* {ENTRY,EXIT} */
60#include <asm/entry.h>
61#include <asm/irqflags.h>
62
63 .cpu A7
64
65;############################ Vector Table #################################
66
67.macro VECTOR lbl
68#if 1 /* Just in case, build breaks */
69 j \lbl
70#else
71 b \lbl
72 nop
73#endif
74.endm
75
76 .section .vector, "ax",@progbits
77 .align 4
78
79/* Each entry in the vector table must occupy 2 words. Since it is a jump
80 * across sections (.vector to .text) we are guaranteed that 'j somewhere'
81 * will use the 'j limm' form of the instruction as long as somewhere is in
82 * a section other than .vector.
83 */
84
85; ********* Critical System Events **********************
86VECTOR res_service ; 0x0, Reset Vector (0x0)
87VECTOR mem_service ; 0x8, Mem exception (0x1)
88VECTOR instr_service ; 0x10, Instrn Error (0x2)
89
90; ******************** Device ISRs **********************
91#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
92VECTOR handle_interrupt_level2
93#else
94VECTOR handle_interrupt_level1
95#endif
96
97.rept 28
98VECTOR handle_interrupt_level1 ; Other devices
99.endr
100
101/* FOR ARC600: timer = 0x3, uart = 0x8, emac = 0x10 */
102
103; ******************** Exceptions **********************
104VECTOR EV_MachineCheck ; 0x100, Fatal Machine check (0x20)
105VECTOR EV_TLBMissI ; 0x108, Instruction TLB miss (0x21)
106VECTOR EV_TLBMissD ; 0x110, Data TLB miss (0x22)
107VECTOR EV_TLBProtV ; 0x118, Protection Violation (0x23)
108 ; or Misaligned Access
109VECTOR EV_PrivilegeV ; 0x120, Privilege Violation (0x24)
110VECTOR EV_Trap ; 0x128, Trap exception (0x25)
111VECTOR EV_Extension ; 0x130, Extn Instruction Excp (0x26)
112
113.rept 24
114VECTOR reserved ; Reserved Exceptions
115.endr
116
117
118;##################### Scratch Mem for IRQ stack switching #############
119
120ARCFP_DATA int1_saved_reg
121 .align 32
122 .type int1_saved_reg, @object
123 .size int1_saved_reg, 4
124int1_saved_reg:
125 .zero 4
126
127/* Each Interrupt level needs its own scratch */
128ARCFP_DATA int2_saved_reg
129 .type int2_saved_reg, @object
130 .size int2_saved_reg, 4
131int2_saved_reg:
132 .zero 4
133
134; ---------------------------------------------
135 .section .text, "ax",@progbits
136
137
138reserved:
139 flag 1 ; Unexpected event, halt
140
141;##################### Interrupt Handling ##############################
142
143#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
144; ---------------------------------------------
145; Level 2 ISR: Can interrupt a Level 1 ISR
146; ---------------------------------------------
147ENTRY(handle_interrupt_level2)
148
149 INTERRUPT_PROLOGUE 2
150
151 ;------------------------------------------------------
152 ; if L2 IRQ interrupted a L1 ISR, disable preemption
153 ;
154 ; This is to avoid a potential L1-L2-L1 scenario
155 ; -L1 IRQ taken
156 ; -L2 interrupts L1 (before L1 ISR could run)
157 ; -preemption off IRQ, user task in syscall picked to run
158 ; -RTIE to userspace
159 ; Returns from L2 context fine
160 ; But both L1 and L2 re-enabled, so another L1 can be taken
161 ; while prev L1 is still unserviced
162 ;
163 ;------------------------------------------------------
164
165 ; L2 interrupting L1 implies both L2 and L1 active
166 ; However both A2 and A1 are NOT set in STATUS32, thus
167 ; need to check STATUS32_L2 to determine if L1 was active
168
169 ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs)
170 bbit0 r9, STATUS_A1_BIT, 1f ; L1 not active when L2 IRQ, so normal
171
172 ; bump thread_info->preempt_count (Disable preemption)
173 GET_CURR_THR_INFO_FROM_SP r10
174 ld r9, [r10, THREAD_INFO_PREEMPT_COUNT]
175 add r9, r9, 1
176 st r9, [r10, THREAD_INFO_PREEMPT_COUNT]
177
1781:
179 ;------------------------------------------------------
180 ; setup params for Linux common ISR and invoke it
181 ;------------------------------------------------------
182 lr r0, [icause2]
183 and r0, r0, 0x1f
184
185 bl.d @arch_do_IRQ
186 mov r1, sp
187
188 mov r8,0x2
189 sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg
190
191 b ret_from_exception
192
193END(handle_interrupt_level2)
194
195#endif
196
197; ---------------------------------------------
198; User Mode Memory Bus Error Interrupt Handler
199; (Kernel mode memory errors handled via separate exception vectors)
200; ---------------------------------------------
201ENTRY(mem_service)
202
203 INTERRUPT_PROLOGUE 2
204
205 mov r0, ilink2
206 mov r1, sp
207
208 ; User process needs to be killed with SIGBUS, but first need to get
209 ; out of the L2 interrupt context (drop to pure kernel mode) and jump
210 ; off to "C" code where SIGBUS in enqueued
211 lr r3, [status32]
212 bclr r3, r3, STATUS_A2_BIT
213 or r3, r3, (STATUS_E1_MASK|STATUS_E2_MASK)
214 sr r3, [status32_l2]
215 mov ilink2, 1f
216 rtie
2171:
218 bl do_memory_error
219 b ret_from_exception
220END(mem_service)
221
222; ---------------------------------------------
223; Level 1 ISR
224; ---------------------------------------------
225ENTRY(handle_interrupt_level1)
226
227 INTERRUPT_PROLOGUE 1
228
229 lr r0, [icause1]
230 and r0, r0, 0x1f
231
232#ifdef CONFIG_TRACE_IRQFLAGS
233 ; icause1 needs to be read early, before calling tracing, which
234 ; can clobber scratch regs, hence use of stack to stash it
235 push r0
236 TRACE_ASM_IRQ_DISABLE
237 pop r0
238#endif
239
240 bl.d @arch_do_IRQ
241 mov r1, sp
242
243 mov r8,0x1
244 sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg
245
246 b ret_from_exception
247END(handle_interrupt_level1)
248
249;################### Non TLB Exception Handling #############################
250
251; ---------------------------------------------
252; Protection Violation Exception Handler
253; ---------------------------------------------
254
255ENTRY(EV_TLBProtV)
256
257 EXCEPTION_PROLOGUE ; ECR returned in r10
258
259 ;------ (5) Type of Protection Violation? ----------
260 ;
261 ; ProtV Hardware Exception is triggered for Access Faults of 2 types
262 ; -Access Violation : 00_23_(00|01|02|03)_00
263 ; x r w r+w
264 ; -Unaligned Access : 00_23_04_00
265 bbit1 r10, ECR_C_BIT_PROTV_MISALIG_DATA, 4f
266
267 ;========= (6a) Access Violation Processing ========
268 bl do_page_fault
269 b ret_from_exception
270
271 ;========== (6b) Non aligned access ============
2724:
273
274 SAVE_CALLEE_SAVED_USER
275 mov r2, sp ; callee_regs
276
277 bl do_misaligned_access
278
279 ; TBD: optimize - do this only if a callee reg was involved
280 ; either a dst of emulated LD/ST or src with address-writeback
281 RESTORE_CALLEE_SAVED_USER
282
283 b ret_from_exception
284
285END(EV_TLBProtV)
286
287; Wrapper for Linux page fault handler called from EV_TLBMiss*
288; Very similar to ProtV handler case (6a) above, but avoids the extra checks
289; for Misaligned access
290;
291ENTRY(call_do_page_fault)
292
293 EXCEPTION_PROLOGUE
294
295 mov blink, ret_from_exception
296 b do_page_fault
297
298END(call_do_page_fault)
299
300;############# Common Handlers for ARCompact and ARCv2 ##############
301
302#include "entry.S"
303
304;############# Return from Intr/Excp/Trap (ARC Specifics) ##############
305;
306; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap)
307; IRQ shd definitely not happen between now and rtie
308; All 2 entry points to here already disable interrupts
309
310.Lrestore_regs:
311
312 # Interrupts are actually disabled from this point on, but will get
313 # reenabled after we return from interrupt/exception.
314 # But irq tracer needs to be told now...
315 TRACE_ASM_IRQ_ENABLE
316
317 lr r10, [status32]
318
319 ; Restore REG File. In case multiple Events outstanding,
320 ; use the same priority as rtie: EXCPN, L2 IRQ, L1 IRQ, None
321 ; Note that we use realtime STATUS32 (not pt_regs->status32) to
322 ; decide that.
323
324 and.f 0, r10, (STATUS_A1_MASK|STATUS_A2_MASK)
325 bz .Lexcep_or_pure_K_ret
326
327 ; Returning from Interrupts (Level 1 or 2)
328
329#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
330
331 ; Level 2 interrupt return Path - from hardware standpoint
332 bbit0 r10, STATUS_A2_BIT, not_level2_interrupt
333
334 ;------------------------------------------------------------------
335 ; However the context returning might not have taken L2 intr itself
336 ; e.g. Task'A' user-code -> L2 intr -> schedule -> 'B' user-code ret
337 ; Special considerations needed for the context which took L2 intr
338
339 ld r9, [sp, PT_event] ; Ensure this is L2 intr context
340 brne r9, event_IRQ2, 149f
341
342 ;------------------------------------------------------------------
343 ; if L2 IRQ interrupted an L1 ISR, we'd disabled preemption earlier
344 ; so that sched doesn't move to new task, causing L1 to be delayed
345 ; undeterministically. Now that we've achieved that, let's reset
346 ; things to what they were, before returning from L2 context
347 ;----------------------------------------------------------------
348
349 ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs)
350 bbit0 r9, STATUS_A1_BIT, 149f ; L1 not active when L2 IRQ, so normal
351
352 ; decrement thread_info->preempt_count (re-enable preemption)
353 GET_CURR_THR_INFO_FROM_SP r10
354 ld r9, [r10, THREAD_INFO_PREEMPT_COUNT]
355
356 ; paranoid check, given A1 was active when A2 happened, preempt count
357 ; must not be 0 because we would have incremented it.
358 ; If this does happen we simply HALT as it means a BUG !!!
359 cmp r9, 0
360 bnz 2f
361 flag 1
362
3632:
364 sub r9, r9, 1
365 st r9, [r10, THREAD_INFO_PREEMPT_COUNT]
366
367149:
368 INTERRUPT_EPILOGUE 2 ; return from level 2 interrupt
369debug_marker_l2:
370 rtie
371
372not_level2_interrupt:
373
374#endif
375
376 INTERRUPT_EPILOGUE 1 ; return from level 1 interrupt
377debug_marker_l1:
378 rtie
379
380.Lexcep_or_pure_K_ret:
381
382 ;this case is for syscalls or Exceptions or pure kernel mode
383
384 EXCEPTION_EPILOGUE
385debug_marker_syscall:
386 rtie
387
388END(ret_from_exception)