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1#include <linux/init.h>
2#include <linux/linkage.h>
3
4#include <asm/assembler.h>
5#include <asm/asm-offsets.h>
6#include <asm/errno.h>
7#include <asm/thread_info.h>
8#include <asm/v7m.h>
9
10@ Bad Abort numbers
11@ -----------------
12@
13#define BAD_PREFETCH 0
14#define BAD_DATA 1
15#define BAD_ADDREXCPTN 2
16#define BAD_IRQ 3
17#define BAD_UNDEFINSTR 4
18
19@
20@ Most of the stack format comes from struct pt_regs, but with
21@ the addition of 8 bytes for storing syscall args 5 and 6.
22@ This _must_ remain a multiple of 8 for EABI.
23@
24#define S_OFF 8
25
26/*
27 * The SWI code relies on the fact that R0 is at the bottom of the stack
28 * (due to slow/fast restore user regs).
29 */
30#if S_R0 != 0
31#error "Please fix"
32#endif
33
34 .macro zero_fp
35#ifdef CONFIG_FRAME_POINTER
36 mov fp, #0
37#endif
38 .endm
39
40#ifdef CONFIG_ALIGNMENT_TRAP
41#define ATRAP(x...) x
42#else
43#define ATRAP(x...)
44#endif
45
46 .macro alignment_trap, rtmp1, rtmp2, label
47#ifdef CONFIG_ALIGNMENT_TRAP
48 mrc p15, 0, \rtmp2, c1, c0, 0
49 ldr \rtmp1, \label
50 ldr \rtmp1, [\rtmp1]
51 teq \rtmp1, \rtmp2
52 mcrne p15, 0, \rtmp1, c1, c0, 0
53#endif
54 .endm
55
56#ifdef CONFIG_CPU_V7M
57/*
58 * ARMv7-M exception entry/exit macros.
59 *
60 * xPSR, ReturnAddress(), LR (R14), R12, R3, R2, R1, and R0 are
61 * automatically saved on the current stack (32 words) before
62 * switching to the exception stack (SP_main).
63 *
64 * If exception is taken while in user mode, SP_main is
65 * empty. Otherwise, SP_main is aligned to 64 bit automatically
66 * (CCR.STKALIGN set).
67 *
68 * Linux assumes that the interrupts are disabled when entering an
69 * exception handler and it may BUG if this is not the case. Interrupts
70 * are disabled during entry and reenabled in the exit macro.
71 *
72 * v7m_exception_slow_exit is used when returning from SVC or PendSV.
73 * When returning to kernel mode, we don't return from exception.
74 */
75 .macro v7m_exception_entry
76 @ determine the location of the registers saved by the core during
77 @ exception entry. Depending on the mode the cpu was in when the
78 @ exception happend that is either on the main or the process stack.
79 @ Bit 2 of EXC_RETURN stored in the lr register specifies which stack
80 @ was used.
81 tst lr, #EXC_RET_STACK_MASK
82 mrsne r12, psp
83 moveq r12, sp
84
85 @ we cannot rely on r0-r3 and r12 matching the value saved in the
86 @ exception frame because of tail-chaining. So these have to be
87 @ reloaded.
88 ldmia r12!, {r0-r3}
89
90 @ Linux expects to have irqs off. Do it here before taking stack space
91 cpsid i
92
93 sub sp, #S_FRAME_SIZE-S_IP
94 stmdb sp!, {r0-r11}
95
96 @ load saved r12, lr, return address and xPSR.
97 @ r0-r7 are used for signals and never touched from now on. Clobbering
98 @ r8-r12 is OK.
99 mov r9, r12
100 ldmia r9!, {r8, r10-r12}
101
102 @ calculate the original stack pointer value.
103 @ r9 currently points to the memory location just above the auto saved
104 @ xPSR.
105 @ The cpu might automatically 8-byte align the stack. Bit 9
106 @ of the saved xPSR specifies if stack aligning took place. In this case
107 @ another 32-bit value is included in the stack.
108
109 tst r12, V7M_xPSR_FRAMEPTRALIGN
110 addne r9, r9, #4
111
112 @ store saved r12 using str to have a register to hold the base for stm
113 str r8, [sp, #S_IP]
114 add r8, sp, #S_SP
115 @ store r13-r15, xPSR
116 stmia r8!, {r9-r12}
117 @ store old_r0
118 str r0, [r8]
119 .endm
120
121 /*
122 * PENDSV and SVCALL are configured to have the same exception
123 * priorities. As a kernel thread runs at SVCALL execution priority it
124 * can never be preempted and so we will never have to return to a
125 * kernel thread here.
126 */
127 .macro v7m_exception_slow_exit ret_r0
128 cpsid i
129 ldr lr, =EXC_RET_THREADMODE_PROCESSSTACK
130
131 @ read original r12, sp, lr, pc and xPSR
132 add r12, sp, #S_IP
133 ldmia r12, {r1-r5}
134
135 @ an exception frame is always 8-byte aligned. To tell the hardware if
136 @ the sp to be restored is aligned or not set bit 9 of the saved xPSR
137 @ accordingly.
138 tst r2, #4
139 subne r2, r2, #4
140 orrne r5, V7M_xPSR_FRAMEPTRALIGN
141 biceq r5, V7M_xPSR_FRAMEPTRALIGN
142
143 @ ensure bit 0 is cleared in the PC, otherwise behaviour is
144 @ unpredictable
145 bic r4, #1
146
147 @ write basic exception frame
148 stmdb r2!, {r1, r3-r5}
149 ldmia sp, {r1, r3-r5}
150 .if \ret_r0
151 stmdb r2!, {r0, r3-r5}
152 .else
153 stmdb r2!, {r1, r3-r5}
154 .endif
155
156 @ restore process sp
157 msr psp, r2
158
159 @ restore original r4-r11
160 ldmia sp!, {r0-r11}
161
162 @ restore main sp
163 add sp, sp, #S_FRAME_SIZE-S_IP
164
165 cpsie i
166 bx lr
167 .endm
168#endif /* CONFIG_CPU_V7M */
169
170 @
171 @ Store/load the USER SP and LR registers by switching to the SYS
172 @ mode. Useful in Thumb-2 mode where "stm/ldm rd, {sp, lr}^" is not
173 @ available. Should only be called from SVC mode
174 @
175 .macro store_user_sp_lr, rd, rtemp, offset = 0
176 mrs \rtemp, cpsr
177 eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
178 msr cpsr_c, \rtemp @ switch to the SYS mode
179
180 str sp, [\rd, #\offset] @ save sp_usr
181 str lr, [\rd, #\offset + 4] @ save lr_usr
182
183 eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
184 msr cpsr_c, \rtemp @ switch back to the SVC mode
185 .endm
186
187 .macro load_user_sp_lr, rd, rtemp, offset = 0
188 mrs \rtemp, cpsr
189 eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
190 msr cpsr_c, \rtemp @ switch to the SYS mode
191
192 ldr sp, [\rd, #\offset] @ load sp_usr
193 ldr lr, [\rd, #\offset + 4] @ load lr_usr
194
195 eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
196 msr cpsr_c, \rtemp @ switch back to the SVC mode
197 .endm
198
199
200 .macro svc_exit, rpsr, irq = 0
201 .if \irq != 0
202 @ IRQs already off
203#ifdef CONFIG_TRACE_IRQFLAGS
204 @ The parent context IRQs must have been enabled to get here in
205 @ the first place, so there's no point checking the PSR I bit.
206 bl trace_hardirqs_on
207#endif
208 .else
209 @ IRQs off again before pulling preserved data off the stack
210 disable_irq_notrace
211#ifdef CONFIG_TRACE_IRQFLAGS
212 tst \rpsr, #PSR_I_BIT
213 bleq trace_hardirqs_on
214 tst \rpsr, #PSR_I_BIT
215 blne trace_hardirqs_off
216#endif
217 .endif
218 uaccess_restore
219
220#ifndef CONFIG_THUMB2_KERNEL
221 @ ARM mode SVC restore
222 msr spsr_cxsf, \rpsr
223#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)
224 @ We must avoid clrex due to Cortex-A15 erratum #830321
225 sub r0, sp, #4 @ uninhabited address
226 strex r1, r2, [r0] @ clear the exclusive monitor
227#endif
228 ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
229#else
230 @ Thumb mode SVC restore
231 ldr lr, [sp, #S_SP] @ top of the stack
232 ldrd r0, r1, [sp, #S_LR] @ calling lr and pc
233
234 @ We must avoid clrex due to Cortex-A15 erratum #830321
235 strex r2, r1, [sp, #S_LR] @ clear the exclusive monitor
236
237 stmdb lr!, {r0, r1, \rpsr} @ calling lr and rfe context
238 ldmia sp, {r0 - r12}
239 mov sp, lr
240 ldr lr, [sp], #4
241 rfeia sp!
242#endif
243 .endm
244
245 @
246 @ svc_exit_via_fiq - like svc_exit but switches to FIQ mode before exit
247 @
248 @ This macro acts in a similar manner to svc_exit but switches to FIQ
249 @ mode to restore the final part of the register state.
250 @
251 @ We cannot use the normal svc_exit procedure because that would
252 @ clobber spsr_svc (FIQ could be delivered during the first few
253 @ instructions of vector_swi meaning its contents have not been
254 @ saved anywhere).
255 @
256 @ Note that, unlike svc_exit, this macro also does not allow a caller
257 @ supplied rpsr. This is because the FIQ exceptions are not re-entrant
258 @ and the handlers cannot call into the scheduler (meaning the value
259 @ on the stack remains correct).
260 @
261 .macro svc_exit_via_fiq
262 uaccess_restore
263#ifndef CONFIG_THUMB2_KERNEL
264 @ ARM mode restore
265 mov r0, sp
266 ldmib r0, {r1 - r14} @ abort is deadly from here onward (it will
267 @ clobber state restored below)
268 msr cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT
269 add r8, r0, #S_PC
270 ldr r9, [r0, #S_PSR]
271 msr spsr_cxsf, r9
272 ldr r0, [r0, #S_R0]
273 ldmia r8, {pc}^
274#else
275 @ Thumb mode restore
276 add r0, sp, #S_R2
277 ldr lr, [sp, #S_LR]
278 ldr sp, [sp, #S_SP] @ abort is deadly from here onward (it will
279 @ clobber state restored below)
280 ldmia r0, {r2 - r12}
281 mov r1, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT
282 msr cpsr_c, r1
283 sub r0, #S_R2
284 add r8, r0, #S_PC
285 ldmia r0, {r0 - r1}
286 rfeia r8
287#endif
288 .endm
289
290
291 .macro restore_user_regs, fast = 0, offset = 0
292 uaccess_enable r1, isb=0
293#ifndef CONFIG_THUMB2_KERNEL
294 @ ARM mode restore
295 mov r2, sp
296 ldr r1, [r2, #\offset + S_PSR] @ get calling cpsr
297 ldr lr, [r2, #\offset + S_PC]! @ get pc
298 msr spsr_cxsf, r1 @ save in spsr_svc
299#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)
300 @ We must avoid clrex due to Cortex-A15 erratum #830321
301 strex r1, r2, [r2] @ clear the exclusive monitor
302#endif
303 .if \fast
304 ldmdb r2, {r1 - lr}^ @ get calling r1 - lr
305 .else
306 ldmdb r2, {r0 - lr}^ @ get calling r0 - lr
307 .endif
308 mov r0, r0 @ ARMv5T and earlier require a nop
309 @ after ldm {}^
310 add sp, sp, #\offset + S_FRAME_SIZE
311 movs pc, lr @ return & move spsr_svc into cpsr
312#elif defined(CONFIG_CPU_V7M)
313 @ V7M restore.
314 @ Note that we don't need to do clrex here as clearing the local
315 @ monitor is part of the exception entry and exit sequence.
316 .if \offset
317 add sp, #\offset
318 .endif
319 v7m_exception_slow_exit ret_r0 = \fast
320#else
321 @ Thumb mode restore
322 mov r2, sp
323 load_user_sp_lr r2, r3, \offset + S_SP @ calling sp, lr
324 ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
325 ldr lr, [sp, #\offset + S_PC] @ get pc
326 add sp, sp, #\offset + S_SP
327 msr spsr_cxsf, r1 @ save in spsr_svc
328
329 @ We must avoid clrex due to Cortex-A15 erratum #830321
330 strex r1, r2, [sp] @ clear the exclusive monitor
331
332 .if \fast
333 ldmdb sp, {r1 - r12} @ get calling r1 - r12
334 .else
335 ldmdb sp, {r0 - r12} @ get calling r0 - r12
336 .endif
337 add sp, sp, #S_FRAME_SIZE - S_SP
338 movs pc, lr @ return & move spsr_svc into cpsr
339#endif /* !CONFIG_THUMB2_KERNEL */
340 .endm
341
342/*
343 * Context tracking subsystem. Used to instrument transitions
344 * between user and kernel mode.
345 */
346 .macro ct_user_exit, save = 1
347#ifdef CONFIG_CONTEXT_TRACKING
348 .if \save
349 stmdb sp!, {r0-r3, ip, lr}
350 bl context_tracking_user_exit
351 ldmia sp!, {r0-r3, ip, lr}
352 .else
353 bl context_tracking_user_exit
354 .endif
355#endif
356 .endm
357
358 .macro ct_user_enter, save = 1
359#ifdef CONFIG_CONTEXT_TRACKING
360 .if \save
361 stmdb sp!, {r0-r3, ip, lr}
362 bl context_tracking_user_enter
363 ldmia sp!, {r0-r3, ip, lr}
364 .else
365 bl context_tracking_user_enter
366 .endif
367#endif
368 .endm
369
370/*
371 * These are the registers used in the syscall handler, and allow us to
372 * have in theory up to 7 arguments to a function - r0 to r6.
373 *
374 * r7 is reserved for the system call number for thumb mode.
375 *
376 * Note that tbl == why is intentional.
377 *
378 * We must set at least "tsk" and "why" when calling ret_with_reschedule.
379 */
380scno .req r7 @ syscall number
381tbl .req r8 @ syscall table pointer
382why .req r8 @ Linux syscall (!= 0)
383tsk .req r9 @ current thread_info
1#include <linux/init.h>
2#include <linux/linkage.h>
3
4#include <asm/assembler.h>
5#include <asm/asm-offsets.h>
6#include <asm/errno.h>
7#include <asm/thread_info.h>
8
9@ Bad Abort numbers
10@ -----------------
11@
12#define BAD_PREFETCH 0
13#define BAD_DATA 1
14#define BAD_ADDREXCPTN 2
15#define BAD_IRQ 3
16#define BAD_UNDEFINSTR 4
17
18@
19@ Most of the stack format comes from struct pt_regs, but with
20@ the addition of 8 bytes for storing syscall args 5 and 6.
21@ This _must_ remain a multiple of 8 for EABI.
22@
23#define S_OFF 8
24
25/*
26 * The SWI code relies on the fact that R0 is at the bottom of the stack
27 * (due to slow/fast restore user regs).
28 */
29#if S_R0 != 0
30#error "Please fix"
31#endif
32
33 .macro zero_fp
34#ifdef CONFIG_FRAME_POINTER
35 mov fp, #0
36#endif
37 .endm
38
39 .macro alignment_trap, rtemp
40#ifdef CONFIG_ALIGNMENT_TRAP
41 ldr \rtemp, .LCcralign
42 ldr \rtemp, [\rtemp]
43 mcr p15, 0, \rtemp, c1, c0
44#endif
45 .endm
46
47 @
48 @ Store/load the USER SP and LR registers by switching to the SYS
49 @ mode. Useful in Thumb-2 mode where "stm/ldm rd, {sp, lr}^" is not
50 @ available. Should only be called from SVC mode
51 @
52 .macro store_user_sp_lr, rd, rtemp, offset = 0
53 mrs \rtemp, cpsr
54 eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
55 msr cpsr_c, \rtemp @ switch to the SYS mode
56
57 str sp, [\rd, #\offset] @ save sp_usr
58 str lr, [\rd, #\offset + 4] @ save lr_usr
59
60 eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
61 msr cpsr_c, \rtemp @ switch back to the SVC mode
62 .endm
63
64 .macro load_user_sp_lr, rd, rtemp, offset = 0
65 mrs \rtemp, cpsr
66 eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
67 msr cpsr_c, \rtemp @ switch to the SYS mode
68
69 ldr sp, [\rd, #\offset] @ load sp_usr
70 ldr lr, [\rd, #\offset + 4] @ load lr_usr
71
72 eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
73 msr cpsr_c, \rtemp @ switch back to the SVC mode
74 .endm
75
76#ifndef CONFIG_THUMB2_KERNEL
77 .macro svc_exit, rpsr
78 msr spsr_cxsf, \rpsr
79#if defined(CONFIG_CPU_V6)
80 ldr r0, [sp]
81 strex r1, r2, [sp] @ clear the exclusive monitor
82 ldmib sp, {r1 - pc}^ @ load r1 - pc, cpsr
83#elif defined(CONFIG_CPU_32v6K)
84 clrex @ clear the exclusive monitor
85 ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
86#else
87 ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
88#endif
89 .endm
90
91 .macro restore_user_regs, fast = 0, offset = 0
92 ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
93 ldr lr, [sp, #\offset + S_PC]! @ get pc
94 msr spsr_cxsf, r1 @ save in spsr_svc
95#if defined(CONFIG_CPU_V6)
96 strex r1, r2, [sp] @ clear the exclusive monitor
97#elif defined(CONFIG_CPU_32v6K)
98 clrex @ clear the exclusive monitor
99#endif
100 .if \fast
101 ldmdb sp, {r1 - lr}^ @ get calling r1 - lr
102 .else
103 ldmdb sp, {r0 - lr}^ @ get calling r0 - lr
104 .endif
105 mov r0, r0 @ ARMv5T and earlier require a nop
106 @ after ldm {}^
107 add sp, sp, #S_FRAME_SIZE - S_PC
108 movs pc, lr @ return & move spsr_svc into cpsr
109 .endm
110
111 .macro get_thread_info, rd
112 mov \rd, sp, lsr #13
113 mov \rd, \rd, lsl #13
114 .endm
115
116 @
117 @ 32-bit wide "mov pc, reg"
118 @
119 .macro movw_pc, reg
120 mov pc, \reg
121 .endm
122#else /* CONFIG_THUMB2_KERNEL */
123 .macro svc_exit, rpsr
124 ldr lr, [sp, #S_SP] @ top of the stack
125 ldrd r0, r1, [sp, #S_LR] @ calling lr and pc
126 clrex @ clear the exclusive monitor
127 stmdb lr!, {r0, r1, \rpsr} @ calling lr and rfe context
128 ldmia sp, {r0 - r12}
129 mov sp, lr
130 ldr lr, [sp], #4
131 rfeia sp!
132 .endm
133
134 .macro restore_user_regs, fast = 0, offset = 0
135 clrex @ clear the exclusive monitor
136 mov r2, sp
137 load_user_sp_lr r2, r3, \offset + S_SP @ calling sp, lr
138 ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
139 ldr lr, [sp, #\offset + S_PC] @ get pc
140 add sp, sp, #\offset + S_SP
141 msr spsr_cxsf, r1 @ save in spsr_svc
142 .if \fast
143 ldmdb sp, {r1 - r12} @ get calling r1 - r12
144 .else
145 ldmdb sp, {r0 - r12} @ get calling r0 - r12
146 .endif
147 add sp, sp, #S_FRAME_SIZE - S_SP
148 movs pc, lr @ return & move spsr_svc into cpsr
149 .endm
150
151 .macro get_thread_info, rd
152 mov \rd, sp
153 lsr \rd, \rd, #13
154 mov \rd, \rd, lsl #13
155 .endm
156
157 @
158 @ 32-bit wide "mov pc, reg"
159 @
160 .macro movw_pc, reg
161 mov pc, \reg
162 nop
163 .endm
164#endif /* !CONFIG_THUMB2_KERNEL */
165
166/*
167 * These are the registers used in the syscall handler, and allow us to
168 * have in theory up to 7 arguments to a function - r0 to r6.
169 *
170 * r7 is reserved for the system call number for thumb mode.
171 *
172 * Note that tbl == why is intentional.
173 *
174 * We must set at least "tsk" and "why" when calling ret_with_reschedule.
175 */
176scno .req r7 @ syscall number
177tbl .req r8 @ syscall table pointer
178why .req r8 @ Linux syscall (!= 0)
179tsk .req r9 @ current thread_info