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1/*
2 * linux/arch/arm/kernel/entry-common.S
3 *
4 * Copyright (C) 2000 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <asm/unistd.h>
12#include <asm/ftrace.h>
13#include <asm/unwind.h>
14
15#ifdef CONFIG_NEED_RET_TO_USER
16#include <mach/entry-macro.S>
17#else
18 .macro arch_ret_to_user, tmp1, tmp2
19 .endm
20#endif
21
22#include "entry-header.S"
23
24
25 .align 5
26/*
27 * This is the fast syscall return path. We do as little as
28 * possible here, and this includes saving r0 back into the SVC
29 * stack.
30 */
31ret_fast_syscall:
32 UNWIND(.fnstart )
33 UNWIND(.cantunwind )
34 disable_irq @ disable interrupts
35 ldr r1, [tsk, #TI_FLAGS]
36 tst r1, #_TIF_WORK_MASK
37 bne fast_work_pending
38#if defined(CONFIG_IRQSOFF_TRACER)
39 asm_trace_hardirqs_on
40#endif
41
42 /* perform architecture specific actions before user return */
43 arch_ret_to_user r1, lr
44
45 restore_user_regs fast = 1, offset = S_OFF
46 UNWIND(.fnend )
47
48/*
49 * Ok, we need to do extra processing, enter the slow path.
50 */
51fast_work_pending:
52 str r0, [sp, #S_R0+S_OFF]! @ returned r0
53work_pending:
54 tst r1, #_TIF_NEED_RESCHED
55 bne work_resched
56 /*
57 * TIF_SIGPENDING or TIF_NOTIFY_RESUME must've been set if we got here
58 */
59 ldr r2, [sp, #S_PSR]
60 mov r0, sp @ 'regs'
61 tst r2, #15 @ are we returning to user mode?
62 bne no_work_pending @ no? just leave, then...
63 mov r2, why @ 'syscall'
64 tst r1, #_TIF_SIGPENDING @ delivering a signal?
65 movne why, #0 @ prevent further restarts
66 bl do_notify_resume
67 b ret_slow_syscall @ Check work again
68
69work_resched:
70 bl schedule
71/*
72 * "slow" syscall return path. "why" tells us if this was a real syscall.
73 */
74ENTRY(ret_to_user)
75ret_slow_syscall:
76 disable_irq @ disable interrupts
77ENTRY(ret_to_user_from_irq)
78 ldr r1, [tsk, #TI_FLAGS]
79 tst r1, #_TIF_WORK_MASK
80 bne work_pending
81no_work_pending:
82#if defined(CONFIG_IRQSOFF_TRACER)
83 asm_trace_hardirqs_on
84#endif
85 /* perform architecture specific actions before user return */
86 arch_ret_to_user r1, lr
87
88 restore_user_regs fast = 0, offset = 0
89ENDPROC(ret_to_user_from_irq)
90ENDPROC(ret_to_user)
91
92/*
93 * This is how we return from a fork.
94 */
95ENTRY(ret_from_fork)
96 bl schedule_tail
97 get_thread_info tsk
98 ldr r1, [tsk, #TI_FLAGS] @ check for syscall tracing
99 mov why, #1
100 tst r1, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
101 beq ret_slow_syscall
102 mov r1, sp
103 mov r0, #1 @ trace exit [IP = 1]
104 bl syscall_trace
105 b ret_slow_syscall
106ENDPROC(ret_from_fork)
107
108 .equ NR_syscalls,0
109#define CALL(x) .equ NR_syscalls,NR_syscalls+1
110#include "calls.S"
111#undef CALL
112#define CALL(x) .long x
113
114#ifdef CONFIG_FUNCTION_TRACER
115/*
116 * When compiling with -pg, gcc inserts a call to the mcount routine at the
117 * start of every function. In mcount, apart from the function's address (in
118 * lr), we need to get hold of the function's caller's address.
119 *
120 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
121 *
122 * bl mcount
123 *
124 * These versions have the limitation that in order for the mcount routine to
125 * be able to determine the function's caller's address, an APCS-style frame
126 * pointer (which is set up with something like the code below) is required.
127 *
128 * mov ip, sp
129 * push {fp, ip, lr, pc}
130 * sub fp, ip, #4
131 *
132 * With EABI, these frame pointers are not available unless -mapcs-frame is
133 * specified, and if building as Thumb-2, not even then.
134 *
135 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
136 * with call sites like:
137 *
138 * push {lr}
139 * bl __gnu_mcount_nc
140 *
141 * With these compilers, frame pointers are not necessary.
142 *
143 * mcount can be thought of as a function called in the middle of a subroutine
144 * call. As such, it needs to be transparent for both the caller and the
145 * callee: the original lr needs to be restored when leaving mcount, and no
146 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we
147 * clobber the ip register. This is OK because the ARM calling convention
148 * allows it to be clobbered in subroutines and doesn't use it to hold
149 * parameters.)
150 *
151 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
152 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
153 * arch/arm/kernel/ftrace.c).
154 */
155
156#ifndef CONFIG_OLD_MCOUNT
157#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
158#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
159#endif
160#endif
161
162.macro mcount_adjust_addr rd, rn
163 bic \rd, \rn, #1 @ clear the Thumb bit if present
164 sub \rd, \rd, #MCOUNT_INSN_SIZE
165.endm
166
167.macro __mcount suffix
168 mcount_enter
169 ldr r0, =ftrace_trace_function
170 ldr r2, [r0]
171 adr r0, .Lftrace_stub
172 cmp r0, r2
173 bne 1f
174
175#ifdef CONFIG_FUNCTION_GRAPH_TRACER
176 ldr r1, =ftrace_graph_return
177 ldr r2, [r1]
178 cmp r0, r2
179 bne ftrace_graph_caller\suffix
180
181 ldr r1, =ftrace_graph_entry
182 ldr r2, [r1]
183 ldr r0, =ftrace_graph_entry_stub
184 cmp r0, r2
185 bne ftrace_graph_caller\suffix
186#endif
187
188 mcount_exit
189
1901: mcount_get_lr r1 @ lr of instrumented func
191 mcount_adjust_addr r0, lr @ instrumented function
192 adr lr, BSYM(2f)
193 mov pc, r2
1942: mcount_exit
195.endm
196
197.macro __ftrace_caller suffix
198 mcount_enter
199
200 mcount_get_lr r1 @ lr of instrumented func
201 mcount_adjust_addr r0, lr @ instrumented function
202
203 .globl ftrace_call\suffix
204ftrace_call\suffix:
205 bl ftrace_stub
206
207#ifdef CONFIG_FUNCTION_GRAPH_TRACER
208 .globl ftrace_graph_call\suffix
209ftrace_graph_call\suffix:
210 mov r0, r0
211#endif
212
213 mcount_exit
214.endm
215
216.macro __ftrace_graph_caller
217 sub r0, fp, #4 @ &lr of instrumented routine (&parent)
218#ifdef CONFIG_DYNAMIC_FTRACE
219 @ called from __ftrace_caller, saved in mcount_enter
220 ldr r1, [sp, #16] @ instrumented routine (func)
221 mcount_adjust_addr r1, r1
222#else
223 @ called from __mcount, untouched in lr
224 mcount_adjust_addr r1, lr @ instrumented routine (func)
225#endif
226 mov r2, fp @ frame pointer
227 bl prepare_ftrace_return
228 mcount_exit
229.endm
230
231#ifdef CONFIG_OLD_MCOUNT
232/*
233 * mcount
234 */
235
236.macro mcount_enter
237 stmdb sp!, {r0-r3, lr}
238.endm
239
240.macro mcount_get_lr reg
241 ldr \reg, [fp, #-4]
242.endm
243
244.macro mcount_exit
245 ldr lr, [fp, #-4]
246 ldmia sp!, {r0-r3, pc}
247.endm
248
249ENTRY(mcount)
250#ifdef CONFIG_DYNAMIC_FTRACE
251 stmdb sp!, {lr}
252 ldr lr, [fp, #-4]
253 ldmia sp!, {pc}
254#else
255 __mcount _old
256#endif
257ENDPROC(mcount)
258
259#ifdef CONFIG_DYNAMIC_FTRACE
260ENTRY(ftrace_caller_old)
261 __ftrace_caller _old
262ENDPROC(ftrace_caller_old)
263#endif
264
265#ifdef CONFIG_FUNCTION_GRAPH_TRACER
266ENTRY(ftrace_graph_caller_old)
267 __ftrace_graph_caller
268ENDPROC(ftrace_graph_caller_old)
269#endif
270
271.purgem mcount_enter
272.purgem mcount_get_lr
273.purgem mcount_exit
274#endif
275
276/*
277 * __gnu_mcount_nc
278 */
279
280.macro mcount_enter
281 stmdb sp!, {r0-r3, lr}
282.endm
283
284.macro mcount_get_lr reg
285 ldr \reg, [sp, #20]
286.endm
287
288.macro mcount_exit
289 ldmia sp!, {r0-r3, ip, lr}
290 mov pc, ip
291.endm
292
293ENTRY(__gnu_mcount_nc)
294#ifdef CONFIG_DYNAMIC_FTRACE
295 mov ip, lr
296 ldmia sp!, {lr}
297 mov pc, ip
298#else
299 __mcount
300#endif
301ENDPROC(__gnu_mcount_nc)
302
303#ifdef CONFIG_DYNAMIC_FTRACE
304ENTRY(ftrace_caller)
305 __ftrace_caller
306ENDPROC(ftrace_caller)
307#endif
308
309#ifdef CONFIG_FUNCTION_GRAPH_TRACER
310ENTRY(ftrace_graph_caller)
311 __ftrace_graph_caller
312ENDPROC(ftrace_graph_caller)
313#endif
314
315.purgem mcount_enter
316.purgem mcount_get_lr
317.purgem mcount_exit
318
319#ifdef CONFIG_FUNCTION_GRAPH_TRACER
320 .globl return_to_handler
321return_to_handler:
322 stmdb sp!, {r0-r3}
323 mov r0, fp @ frame pointer
324 bl ftrace_return_to_handler
325 mov lr, r0 @ r0 has real ret addr
326 ldmia sp!, {r0-r3}
327 mov pc, lr
328#endif
329
330ENTRY(ftrace_stub)
331.Lftrace_stub:
332 mov pc, lr
333ENDPROC(ftrace_stub)
334
335#endif /* CONFIG_FUNCTION_TRACER */
336
337/*=============================================================================
338 * SWI handler
339 *-----------------------------------------------------------------------------
340 */
341
342 .align 5
343ENTRY(vector_swi)
344 sub sp, sp, #S_FRAME_SIZE
345 stmia sp, {r0 - r12} @ Calling r0 - r12
346 ARM( add r8, sp, #S_PC )
347 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
348 THUMB( mov r8, sp )
349 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
350 mrs r8, spsr @ called from non-FIQ mode, so ok.
351 str lr, [sp, #S_PC] @ Save calling PC
352 str r8, [sp, #S_PSR] @ Save CPSR
353 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
354 zero_fp
355
356 /*
357 * Get the system call number.
358 */
359
360#if defined(CONFIG_OABI_COMPAT)
361
362 /*
363 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
364 * value to determine if it is an EABI or an old ABI call.
365 */
366#ifdef CONFIG_ARM_THUMB
367 tst r8, #PSR_T_BIT
368 movne r10, #0 @ no thumb OABI emulation
369 ldreq r10, [lr, #-4] @ get SWI instruction
370#else
371 ldr r10, [lr, #-4] @ get SWI instruction
372#endif
373#ifdef CONFIG_CPU_ENDIAN_BE8
374 rev r10, r10 @ little endian instruction
375#endif
376
377#elif defined(CONFIG_AEABI)
378
379 /*
380 * Pure EABI user space always put syscall number into scno (r7).
381 */
382#elif defined(CONFIG_ARM_THUMB)
383 /* Legacy ABI only, possibly thumb mode. */
384 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
385 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
386 ldreq scno, [lr, #-4]
387
388#else
389 /* Legacy ABI only. */
390 ldr scno, [lr, #-4] @ get SWI instruction
391#endif
392
393#ifdef CONFIG_ALIGNMENT_TRAP
394 ldr ip, __cr_alignment
395 ldr ip, [ip]
396 mcr p15, 0, ip, c1, c0 @ update control register
397#endif
398 enable_irq
399
400 get_thread_info tsk
401 adr tbl, sys_call_table @ load syscall table pointer
402
403#if defined(CONFIG_OABI_COMPAT)
404 /*
405 * If the swi argument is zero, this is an EABI call and we do nothing.
406 *
407 * If this is an old ABI call, get the syscall number into scno and
408 * get the old ABI syscall table address.
409 */
410 bics r10, r10, #0xff000000
411 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
412 ldrne tbl, =sys_oabi_call_table
413#elif !defined(CONFIG_AEABI)
414 bic scno, scno, #0xff000000 @ mask off SWI op-code
415 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
416#endif
417
418 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
419 stmdb sp!, {r4, r5} @ push fifth and sixth args
420
421#ifdef CONFIG_SECCOMP
422 tst r10, #_TIF_SECCOMP
423 beq 1f
424 mov r0, scno
425 bl __secure_computing
426 add r0, sp, #S_R0 + S_OFF @ pointer to regs
427 ldmia r0, {r0 - r3} @ have to reload r0 - r3
4281:
429#endif
430
431 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
432 bne __sys_trace
433
434 cmp scno, #NR_syscalls @ check upper syscall limit
435 adr lr, BSYM(ret_fast_syscall) @ return address
436 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
437
438 add r1, sp, #S_OFF
4392: mov why, #0 @ no longer a real syscall
440 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
441 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
442 bcs arm_syscall
443 b sys_ni_syscall @ not private func
444ENDPROC(vector_swi)
445
446 /*
447 * This is the really slow path. We're going to be doing
448 * context switches, and waiting for our parent to respond.
449 */
450__sys_trace:
451 mov r2, scno
452 add r1, sp, #S_OFF
453 mov r0, #0 @ trace entry [IP = 0]
454 bl syscall_trace
455
456 adr lr, BSYM(__sys_trace_return) @ return address
457 mov scno, r0 @ syscall number (possibly new)
458 add r1, sp, #S_R0 + S_OFF @ pointer to regs
459 cmp scno, #NR_syscalls @ check upper syscall limit
460 ldmccia r1, {r0 - r3} @ have to reload r0 - r3
461 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
462 b 2b
463
464__sys_trace_return:
465 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
466 mov r2, scno
467 mov r1, sp
468 mov r0, #1 @ trace exit [IP = 1]
469 bl syscall_trace
470 b ret_slow_syscall
471
472 .align 5
473#ifdef CONFIG_ALIGNMENT_TRAP
474 .type __cr_alignment, #object
475__cr_alignment:
476 .word cr_alignment
477#endif
478 .ltorg
479
480/*
481 * This is the syscall table declaration for native ABI syscalls.
482 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
483 */
484#define ABI(native, compat) native
485#ifdef CONFIG_AEABI
486#define OBSOLETE(syscall) sys_ni_syscall
487#else
488#define OBSOLETE(syscall) syscall
489#endif
490
491 .type sys_call_table, #object
492ENTRY(sys_call_table)
493#include "calls.S"
494#undef ABI
495#undef OBSOLETE
496
497/*============================================================================
498 * Special system call wrappers
499 */
500@ r0 = syscall number
501@ r8 = syscall table
502sys_syscall:
503 bic scno, r0, #__NR_OABI_SYSCALL_BASE
504 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
505 cmpne scno, #NR_syscalls @ check range
506 stmloia sp, {r5, r6} @ shuffle args
507 movlo r0, r1
508 movlo r1, r2
509 movlo r2, r3
510 movlo r3, r4
511 ldrlo pc, [tbl, scno, lsl #2]
512 b sys_ni_syscall
513ENDPROC(sys_syscall)
514
515sys_fork_wrapper:
516 add r0, sp, #S_OFF
517 b sys_fork
518ENDPROC(sys_fork_wrapper)
519
520sys_vfork_wrapper:
521 add r0, sp, #S_OFF
522 b sys_vfork
523ENDPROC(sys_vfork_wrapper)
524
525sys_execve_wrapper:
526 add r3, sp, #S_OFF
527 b sys_execve
528ENDPROC(sys_execve_wrapper)
529
530sys_clone_wrapper:
531 add ip, sp, #S_OFF
532 str ip, [sp, #4]
533 b sys_clone
534ENDPROC(sys_clone_wrapper)
535
536sys_sigreturn_wrapper:
537 add r0, sp, #S_OFF
538 mov why, #0 @ prevent syscall restart handling
539 b sys_sigreturn
540ENDPROC(sys_sigreturn_wrapper)
541
542sys_rt_sigreturn_wrapper:
543 add r0, sp, #S_OFF
544 mov why, #0 @ prevent syscall restart handling
545 b sys_rt_sigreturn
546ENDPROC(sys_rt_sigreturn_wrapper)
547
548sys_sigaltstack_wrapper:
549 ldr r2, [sp, #S_OFF + S_SP]
550 b do_sigaltstack
551ENDPROC(sys_sigaltstack_wrapper)
552
553sys_statfs64_wrapper:
554 teq r1, #88
555 moveq r1, #84
556 b sys_statfs64
557ENDPROC(sys_statfs64_wrapper)
558
559sys_fstatfs64_wrapper:
560 teq r1, #88
561 moveq r1, #84
562 b sys_fstatfs64
563ENDPROC(sys_fstatfs64_wrapper)
564
565/*
566 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
567 * offset, we return EINVAL.
568 */
569sys_mmap2:
570#if PAGE_SHIFT > 12
571 tst r5, #PGOFF_MASK
572 moveq r5, r5, lsr #PAGE_SHIFT - 12
573 streq r5, [sp, #4]
574 beq sys_mmap_pgoff
575 mov r0, #-EINVAL
576 mov pc, lr
577#else
578 str r5, [sp, #4]
579 b sys_mmap_pgoff
580#endif
581ENDPROC(sys_mmap2)
582
583#ifdef CONFIG_OABI_COMPAT
584
585/*
586 * These are syscalls with argument register differences
587 */
588
589sys_oabi_pread64:
590 stmia sp, {r3, r4}
591 b sys_pread64
592ENDPROC(sys_oabi_pread64)
593
594sys_oabi_pwrite64:
595 stmia sp, {r3, r4}
596 b sys_pwrite64
597ENDPROC(sys_oabi_pwrite64)
598
599sys_oabi_truncate64:
600 mov r3, r2
601 mov r2, r1
602 b sys_truncate64
603ENDPROC(sys_oabi_truncate64)
604
605sys_oabi_ftruncate64:
606 mov r3, r2
607 mov r2, r1
608 b sys_ftruncate64
609ENDPROC(sys_oabi_ftruncate64)
610
611sys_oabi_readahead:
612 str r3, [sp]
613 mov r3, r2
614 mov r2, r1
615 b sys_readahead
616ENDPROC(sys_oabi_readahead)
617
618/*
619 * Let's declare a second syscall table for old ABI binaries
620 * using the compatibility syscall entries.
621 */
622#define ABI(native, compat) compat
623#define OBSOLETE(syscall) syscall
624
625 .type sys_oabi_call_table, #object
626ENTRY(sys_oabi_call_table)
627#include "calls.S"
628#undef ABI
629#undef OBSOLETE
630
631#endif
632
1/*
2 * linux/arch/arm/kernel/entry-common.S
3 *
4 * Copyright (C) 2000 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <asm/unistd.h>
12#include <asm/ftrace.h>
13#include <asm/unwind.h>
14
15#ifdef CONFIG_NEED_RET_TO_USER
16#include <mach/entry-macro.S>
17#else
18 .macro arch_ret_to_user, tmp1, tmp2
19 .endm
20#endif
21
22#include "entry-header.S"
23
24
25 .align 5
26/*
27 * This is the fast syscall return path. We do as little as
28 * possible here, and this includes saving r0 back into the SVC
29 * stack.
30 */
31ret_fast_syscall:
32 UNWIND(.fnstart )
33 UNWIND(.cantunwind )
34 disable_irq @ disable interrupts
35 ldr r1, [tsk, #TI_FLAGS]
36 tst r1, #_TIF_WORK_MASK
37 bne fast_work_pending
38 asm_trace_hardirqs_on
39
40 /* perform architecture specific actions before user return */
41 arch_ret_to_user r1, lr
42 ct_user_enter
43
44 restore_user_regs fast = 1, offset = S_OFF
45 UNWIND(.fnend )
46
47/*
48 * Ok, we need to do extra processing, enter the slow path.
49 */
50fast_work_pending:
51 str r0, [sp, #S_R0+S_OFF]! @ returned r0
52work_pending:
53 mov r0, sp @ 'regs'
54 mov r2, why @ 'syscall'
55 bl do_work_pending
56 cmp r0, #0
57 beq no_work_pending
58 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
59 ldmia sp, {r0 - r6} @ have to reload r0 - r6
60 b local_restart @ ... and off we go
61
62/*
63 * "slow" syscall return path. "why" tells us if this was a real syscall.
64 */
65ENTRY(ret_to_user)
66ret_slow_syscall:
67 disable_irq @ disable interrupts
68ENTRY(ret_to_user_from_irq)
69 ldr r1, [tsk, #TI_FLAGS]
70 tst r1, #_TIF_WORK_MASK
71 bne work_pending
72no_work_pending:
73 asm_trace_hardirqs_on
74
75 /* perform architecture specific actions before user return */
76 arch_ret_to_user r1, lr
77 ct_user_enter save = 0
78
79 restore_user_regs fast = 0, offset = 0
80ENDPROC(ret_to_user_from_irq)
81ENDPROC(ret_to_user)
82
83/*
84 * This is how we return from a fork.
85 */
86ENTRY(ret_from_fork)
87 bl schedule_tail
88 cmp r5, #0
89 movne r0, r4
90 adrne lr, BSYM(1f)
91 movne pc, r5
921: get_thread_info tsk
93 b ret_slow_syscall
94ENDPROC(ret_from_fork)
95
96 .equ NR_syscalls,0
97#define CALL(x) .equ NR_syscalls,NR_syscalls+1
98#include "calls.S"
99
100/*
101 * Ensure that the system call table is equal to __NR_syscalls,
102 * which is the value the rest of the system sees
103 */
104.ifne NR_syscalls - __NR_syscalls
105.error "__NR_syscalls is not equal to the size of the syscall table"
106.endif
107
108#undef CALL
109#define CALL(x) .long x
110
111#ifdef CONFIG_FUNCTION_TRACER
112/*
113 * When compiling with -pg, gcc inserts a call to the mcount routine at the
114 * start of every function. In mcount, apart from the function's address (in
115 * lr), we need to get hold of the function's caller's address.
116 *
117 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
118 *
119 * bl mcount
120 *
121 * These versions have the limitation that in order for the mcount routine to
122 * be able to determine the function's caller's address, an APCS-style frame
123 * pointer (which is set up with something like the code below) is required.
124 *
125 * mov ip, sp
126 * push {fp, ip, lr, pc}
127 * sub fp, ip, #4
128 *
129 * With EABI, these frame pointers are not available unless -mapcs-frame is
130 * specified, and if building as Thumb-2, not even then.
131 *
132 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
133 * with call sites like:
134 *
135 * push {lr}
136 * bl __gnu_mcount_nc
137 *
138 * With these compilers, frame pointers are not necessary.
139 *
140 * mcount can be thought of as a function called in the middle of a subroutine
141 * call. As such, it needs to be transparent for both the caller and the
142 * callee: the original lr needs to be restored when leaving mcount, and no
143 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we
144 * clobber the ip register. This is OK because the ARM calling convention
145 * allows it to be clobbered in subroutines and doesn't use it to hold
146 * parameters.)
147 *
148 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
149 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
150 * arch/arm/kernel/ftrace.c).
151 */
152
153#ifndef CONFIG_OLD_MCOUNT
154#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
155#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
156#endif
157#endif
158
159.macro mcount_adjust_addr rd, rn
160 bic \rd, \rn, #1 @ clear the Thumb bit if present
161 sub \rd, \rd, #MCOUNT_INSN_SIZE
162.endm
163
164.macro __mcount suffix
165 mcount_enter
166 ldr r0, =ftrace_trace_function
167 ldr r2, [r0]
168 adr r0, .Lftrace_stub
169 cmp r0, r2
170 bne 1f
171
172#ifdef CONFIG_FUNCTION_GRAPH_TRACER
173 ldr r1, =ftrace_graph_return
174 ldr r2, [r1]
175 cmp r0, r2
176 bne ftrace_graph_caller\suffix
177
178 ldr r1, =ftrace_graph_entry
179 ldr r2, [r1]
180 ldr r0, =ftrace_graph_entry_stub
181 cmp r0, r2
182 bne ftrace_graph_caller\suffix
183#endif
184
185 mcount_exit
186
1871: mcount_get_lr r1 @ lr of instrumented func
188 mcount_adjust_addr r0, lr @ instrumented function
189 adr lr, BSYM(2f)
190 mov pc, r2
1912: mcount_exit
192.endm
193
194.macro __ftrace_caller suffix
195 mcount_enter
196
197 mcount_get_lr r1 @ lr of instrumented func
198 mcount_adjust_addr r0, lr @ instrumented function
199
200 .globl ftrace_call\suffix
201ftrace_call\suffix:
202 bl ftrace_stub
203
204#ifdef CONFIG_FUNCTION_GRAPH_TRACER
205 .globl ftrace_graph_call\suffix
206ftrace_graph_call\suffix:
207 mov r0, r0
208#endif
209
210 mcount_exit
211.endm
212
213.macro __ftrace_graph_caller
214 sub r0, fp, #4 @ &lr of instrumented routine (&parent)
215#ifdef CONFIG_DYNAMIC_FTRACE
216 @ called from __ftrace_caller, saved in mcount_enter
217 ldr r1, [sp, #16] @ instrumented routine (func)
218 mcount_adjust_addr r1, r1
219#else
220 @ called from __mcount, untouched in lr
221 mcount_adjust_addr r1, lr @ instrumented routine (func)
222#endif
223 mov r2, fp @ frame pointer
224 bl prepare_ftrace_return
225 mcount_exit
226.endm
227
228#ifdef CONFIG_OLD_MCOUNT
229/*
230 * mcount
231 */
232
233.macro mcount_enter
234 stmdb sp!, {r0-r3, lr}
235.endm
236
237.macro mcount_get_lr reg
238 ldr \reg, [fp, #-4]
239.endm
240
241.macro mcount_exit
242 ldr lr, [fp, #-4]
243 ldmia sp!, {r0-r3, pc}
244.endm
245
246ENTRY(mcount)
247#ifdef CONFIG_DYNAMIC_FTRACE
248 stmdb sp!, {lr}
249 ldr lr, [fp, #-4]
250 ldmia sp!, {pc}
251#else
252 __mcount _old
253#endif
254ENDPROC(mcount)
255
256#ifdef CONFIG_DYNAMIC_FTRACE
257ENTRY(ftrace_caller_old)
258 __ftrace_caller _old
259ENDPROC(ftrace_caller_old)
260#endif
261
262#ifdef CONFIG_FUNCTION_GRAPH_TRACER
263ENTRY(ftrace_graph_caller_old)
264 __ftrace_graph_caller
265ENDPROC(ftrace_graph_caller_old)
266#endif
267
268.purgem mcount_enter
269.purgem mcount_get_lr
270.purgem mcount_exit
271#endif
272
273/*
274 * __gnu_mcount_nc
275 */
276
277.macro mcount_enter
278/*
279 * This pad compensates for the push {lr} at the call site. Note that we are
280 * unable to unwind through a function which does not otherwise save its lr.
281 */
282 UNWIND(.pad #4)
283 stmdb sp!, {r0-r3, lr}
284 UNWIND(.save {r0-r3, lr})
285.endm
286
287.macro mcount_get_lr reg
288 ldr \reg, [sp, #20]
289.endm
290
291.macro mcount_exit
292 ldmia sp!, {r0-r3, ip, lr}
293 mov pc, ip
294.endm
295
296ENTRY(__gnu_mcount_nc)
297UNWIND(.fnstart)
298#ifdef CONFIG_DYNAMIC_FTRACE
299 mov ip, lr
300 ldmia sp!, {lr}
301 mov pc, ip
302#else
303 __mcount
304#endif
305UNWIND(.fnend)
306ENDPROC(__gnu_mcount_nc)
307
308#ifdef CONFIG_DYNAMIC_FTRACE
309ENTRY(ftrace_caller)
310UNWIND(.fnstart)
311 __ftrace_caller
312UNWIND(.fnend)
313ENDPROC(ftrace_caller)
314#endif
315
316#ifdef CONFIG_FUNCTION_GRAPH_TRACER
317ENTRY(ftrace_graph_caller)
318UNWIND(.fnstart)
319 __ftrace_graph_caller
320UNWIND(.fnend)
321ENDPROC(ftrace_graph_caller)
322#endif
323
324.purgem mcount_enter
325.purgem mcount_get_lr
326.purgem mcount_exit
327
328#ifdef CONFIG_FUNCTION_GRAPH_TRACER
329 .globl return_to_handler
330return_to_handler:
331 stmdb sp!, {r0-r3}
332 mov r0, fp @ frame pointer
333 bl ftrace_return_to_handler
334 mov lr, r0 @ r0 has real ret addr
335 ldmia sp!, {r0-r3}
336 mov pc, lr
337#endif
338
339ENTRY(ftrace_stub)
340.Lftrace_stub:
341 mov pc, lr
342ENDPROC(ftrace_stub)
343
344#endif /* CONFIG_FUNCTION_TRACER */
345
346/*=============================================================================
347 * SWI handler
348 *-----------------------------------------------------------------------------
349 */
350
351 .align 5
352ENTRY(vector_swi)
353#ifdef CONFIG_CPU_V7M
354 v7m_exception_entry
355#else
356 sub sp, sp, #S_FRAME_SIZE
357 stmia sp, {r0 - r12} @ Calling r0 - r12
358 ARM( add r8, sp, #S_PC )
359 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
360 THUMB( mov r8, sp )
361 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
362 mrs r8, spsr @ called from non-FIQ mode, so ok.
363 str lr, [sp, #S_PC] @ Save calling PC
364 str r8, [sp, #S_PSR] @ Save CPSR
365 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
366#endif
367 zero_fp
368
369#ifdef CONFIG_ALIGNMENT_TRAP
370 ldr ip, __cr_alignment
371 ldr ip, [ip]
372 mcr p15, 0, ip, c1, c0 @ update control register
373#endif
374
375 enable_irq
376 ct_user_exit
377 get_thread_info tsk
378
379 /*
380 * Get the system call number.
381 */
382
383#if defined(CONFIG_OABI_COMPAT)
384
385 /*
386 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
387 * value to determine if it is an EABI or an old ABI call.
388 */
389#ifdef CONFIG_ARM_THUMB
390 tst r8, #PSR_T_BIT
391 movne r10, #0 @ no thumb OABI emulation
392 USER( ldreq r10, [lr, #-4] ) @ get SWI instruction
393#else
394 USER( ldr r10, [lr, #-4] ) @ get SWI instruction
395#endif
396 ARM_BE8(rev r10, r10) @ little endian instruction
397
398#elif defined(CONFIG_AEABI)
399
400 /*
401 * Pure EABI user space always put syscall number into scno (r7).
402 */
403#elif defined(CONFIG_ARM_THUMB)
404 /* Legacy ABI only, possibly thumb mode. */
405 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
406 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
407 USER( ldreq scno, [lr, #-4] )
408
409#else
410 /* Legacy ABI only. */
411 USER( ldr scno, [lr, #-4] ) @ get SWI instruction
412#endif
413
414 adr tbl, sys_call_table @ load syscall table pointer
415
416#if defined(CONFIG_OABI_COMPAT)
417 /*
418 * If the swi argument is zero, this is an EABI call and we do nothing.
419 *
420 * If this is an old ABI call, get the syscall number into scno and
421 * get the old ABI syscall table address.
422 */
423 bics r10, r10, #0xff000000
424 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
425 ldrne tbl, =sys_oabi_call_table
426#elif !defined(CONFIG_AEABI)
427 bic scno, scno, #0xff000000 @ mask off SWI op-code
428 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
429#endif
430
431local_restart:
432 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
433 stmdb sp!, {r4, r5} @ push fifth and sixth args
434
435 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
436 bne __sys_trace
437
438 cmp scno, #NR_syscalls @ check upper syscall limit
439 adr lr, BSYM(ret_fast_syscall) @ return address
440 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
441
442 add r1, sp, #S_OFF
4432: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
444 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
445 bcs arm_syscall
446 mov why, #0 @ no longer a real syscall
447 b sys_ni_syscall @ not private func
448
449#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
450 /*
451 * We failed to handle a fault trying to access the page
452 * containing the swi instruction, but we're not really in a
453 * position to return -EFAULT. Instead, return back to the
454 * instruction and re-enter the user fault handling path trying
455 * to page it in. This will likely result in sending SEGV to the
456 * current task.
457 */
4589001:
459 sub lr, lr, #4
460 str lr, [sp, #S_PC]
461 b ret_fast_syscall
462#endif
463ENDPROC(vector_swi)
464
465 /*
466 * This is the really slow path. We're going to be doing
467 * context switches, and waiting for our parent to respond.
468 */
469__sys_trace:
470 mov r1, scno
471 add r0, sp, #S_OFF
472 bl syscall_trace_enter
473
474 adr lr, BSYM(__sys_trace_return) @ return address
475 mov scno, r0 @ syscall number (possibly new)
476 add r1, sp, #S_R0 + S_OFF @ pointer to regs
477 cmp scno, #NR_syscalls @ check upper syscall limit
478 ldmccia r1, {r0 - r6} @ have to reload r0 - r6
479 stmccia sp, {r4, r5} @ and update the stack args
480 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
481 cmp scno, #-1 @ skip the syscall?
482 bne 2b
483 add sp, sp, #S_OFF @ restore stack
484 b ret_slow_syscall
485
486__sys_trace_return:
487 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
488 mov r0, sp
489 bl syscall_trace_exit
490 b ret_slow_syscall
491
492 .align 5
493#ifdef CONFIG_ALIGNMENT_TRAP
494 .type __cr_alignment, #object
495__cr_alignment:
496 .word cr_alignment
497#endif
498 .ltorg
499
500/*
501 * This is the syscall table declaration for native ABI syscalls.
502 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
503 */
504#define ABI(native, compat) native
505#ifdef CONFIG_AEABI
506#define OBSOLETE(syscall) sys_ni_syscall
507#else
508#define OBSOLETE(syscall) syscall
509#endif
510
511 .type sys_call_table, #object
512ENTRY(sys_call_table)
513#include "calls.S"
514#undef ABI
515#undef OBSOLETE
516
517/*============================================================================
518 * Special system call wrappers
519 */
520@ r0 = syscall number
521@ r8 = syscall table
522sys_syscall:
523 bic scno, r0, #__NR_OABI_SYSCALL_BASE
524 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
525 cmpne scno, #NR_syscalls @ check range
526 stmloia sp, {r5, r6} @ shuffle args
527 movlo r0, r1
528 movlo r1, r2
529 movlo r2, r3
530 movlo r3, r4
531 ldrlo pc, [tbl, scno, lsl #2]
532 b sys_ni_syscall
533ENDPROC(sys_syscall)
534
535sys_sigreturn_wrapper:
536 add r0, sp, #S_OFF
537 mov why, #0 @ prevent syscall restart handling
538 b sys_sigreturn
539ENDPROC(sys_sigreturn_wrapper)
540
541sys_rt_sigreturn_wrapper:
542 add r0, sp, #S_OFF
543 mov why, #0 @ prevent syscall restart handling
544 b sys_rt_sigreturn
545ENDPROC(sys_rt_sigreturn_wrapper)
546
547sys_statfs64_wrapper:
548 teq r1, #88
549 moveq r1, #84
550 b sys_statfs64
551ENDPROC(sys_statfs64_wrapper)
552
553sys_fstatfs64_wrapper:
554 teq r1, #88
555 moveq r1, #84
556 b sys_fstatfs64
557ENDPROC(sys_fstatfs64_wrapper)
558
559/*
560 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
561 * offset, we return EINVAL.
562 */
563sys_mmap2:
564#if PAGE_SHIFT > 12
565 tst r5, #PGOFF_MASK
566 moveq r5, r5, lsr #PAGE_SHIFT - 12
567 streq r5, [sp, #4]
568 beq sys_mmap_pgoff
569 mov r0, #-EINVAL
570 mov pc, lr
571#else
572 str r5, [sp, #4]
573 b sys_mmap_pgoff
574#endif
575ENDPROC(sys_mmap2)
576
577#ifdef CONFIG_OABI_COMPAT
578
579/*
580 * These are syscalls with argument register differences
581 */
582
583sys_oabi_pread64:
584 stmia sp, {r3, r4}
585 b sys_pread64
586ENDPROC(sys_oabi_pread64)
587
588sys_oabi_pwrite64:
589 stmia sp, {r3, r4}
590 b sys_pwrite64
591ENDPROC(sys_oabi_pwrite64)
592
593sys_oabi_truncate64:
594 mov r3, r2
595 mov r2, r1
596 b sys_truncate64
597ENDPROC(sys_oabi_truncate64)
598
599sys_oabi_ftruncate64:
600 mov r3, r2
601 mov r2, r1
602 b sys_ftruncate64
603ENDPROC(sys_oabi_ftruncate64)
604
605sys_oabi_readahead:
606 str r3, [sp]
607 mov r3, r2
608 mov r2, r1
609 b sys_readahead
610ENDPROC(sys_oabi_readahead)
611
612/*
613 * Let's declare a second syscall table for old ABI binaries
614 * using the compatibility syscall entries.
615 */
616#define ABI(native, compat) compat
617#define OBSOLETE(syscall) syscall
618
619 .type sys_oabi_call_table, #object
620ENTRY(sys_oabi_call_table)
621#include "calls.S"
622#undef ABI
623#undef OBSOLETE
624
625#endif
626