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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/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * linux/arch/arm/kernel/entry-common.S
4 *
5 * Copyright (C) 2000 Russell King
6 */
7
8#include <asm/assembler.h>
9#include <asm/unistd.h>
10#include <asm/ftrace.h>
11#include <asm/unwind.h>
12#include <asm/memory.h>
13#ifdef CONFIG_AEABI
14#include <asm/unistd-oabi.h>
15#endif
16
17 .equ NR_syscalls, __NR_syscalls
18
19#ifdef CONFIG_NEED_RET_TO_USER
20#include <mach/entry-macro.S>
21#else
22 .macro arch_ret_to_user, tmp1, tmp2
23 .endm
24#endif
25
26#include "entry-header.S"
27
28saved_psr .req r8
29#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING)
30saved_pc .req r9
31#define TRACE(x...) x
32#else
33saved_pc .req lr
34#define TRACE(x...)
35#endif
36
37 .section .entry.text,"ax",%progbits
38 .align 5
39#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \
40 IS_ENABLED(CONFIG_DEBUG_RSEQ))
41/*
42 * This is the fast syscall return path. We do as little as possible here,
43 * such as avoiding writing r0 to the stack. We only use this path if we
44 * have tracing, context tracking and rseq debug disabled - the overheads
45 * from those features make this path too inefficient.
46 */
47ret_fast_syscall:
48__ret_fast_syscall:
49 UNWIND(.fnstart )
50 UNWIND(.cantunwind )
51 disable_irq_notrace @ disable interrupts
52 ldr r2, [tsk, #TI_ADDR_LIMIT]
53 cmp r2, #TASK_SIZE
54 blne addr_limit_check_failed
55 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
56 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
57 bne fast_work_pending
58
59
60 /* perform architecture specific actions before user return */
61 arch_ret_to_user r1, lr
62
63 restore_user_regs fast = 1, offset = S_OFF
64 UNWIND(.fnend )
65ENDPROC(ret_fast_syscall)
66
67 /* Ok, we need to do extra processing, enter the slow path. */
68fast_work_pending:
69 str r0, [sp, #S_R0+S_OFF]! @ returned r0
70 /* fall through to work_pending */
71#else
72/*
73 * The "replacement" ret_fast_syscall for when tracing, context tracking,
74 * or rseq debug is enabled. As we will need to call out to some C functions,
75 * we save r0 first to avoid needing to save registers around each C function
76 * call.
77 */
78ret_fast_syscall:
79__ret_fast_syscall:
80 UNWIND(.fnstart )
81 UNWIND(.cantunwind )
82 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
83#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
84 /* do_rseq_syscall needs interrupts enabled. */
85 mov r0, sp @ 'regs'
86 bl do_rseq_syscall
87#endif
88 disable_irq_notrace @ disable interrupts
89 ldr r2, [tsk, #TI_ADDR_LIMIT]
90 cmp r2, #TASK_SIZE
91 blne addr_limit_check_failed
92 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
93 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
94 beq no_work_pending
95 UNWIND(.fnend )
96ENDPROC(ret_fast_syscall)
97
98 /* Slower path - fall through to work_pending */
99#endif
100
101 tst r1, #_TIF_SYSCALL_WORK
102 bne __sys_trace_return_nosave
103slow_work_pending:
104 mov r0, sp @ 'regs'
105 mov r2, why @ 'syscall'
106 bl do_work_pending
107 cmp r0, #0
108 beq no_work_pending
109 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
110 ldmia sp, {r0 - r6} @ have to reload r0 - r6
111 b local_restart @ ... and off we go
112ENDPROC(ret_fast_syscall)
113
114/*
115 * "slow" syscall return path. "why" tells us if this was a real syscall.
116 * IRQs may be enabled here, so always disable them. Note that we use the
117 * "notrace" version to avoid calling into the tracing code unnecessarily.
118 * do_work_pending() will update this state if necessary.
119 */
120ENTRY(ret_to_user)
121ret_slow_syscall:
122#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
123 /* do_rseq_syscall needs interrupts enabled. */
124 enable_irq_notrace @ enable interrupts
125 mov r0, sp @ 'regs'
126 bl do_rseq_syscall
127#endif
128 disable_irq_notrace @ disable interrupts
129ENTRY(ret_to_user_from_irq)
130 ldr r2, [tsk, #TI_ADDR_LIMIT]
131 cmp r2, #TASK_SIZE
132 blne addr_limit_check_failed
133 ldr r1, [tsk, #TI_FLAGS]
134 tst r1, #_TIF_WORK_MASK
135 bne slow_work_pending
136no_work_pending:
137 asm_trace_hardirqs_on save = 0
138
139 /* perform architecture specific actions before user return */
140 arch_ret_to_user r1, lr
141 ct_user_enter save = 0
142
143 restore_user_regs fast = 0, offset = 0
144ENDPROC(ret_to_user_from_irq)
145ENDPROC(ret_to_user)
146
147/*
148 * This is how we return from a fork.
149 */
150ENTRY(ret_from_fork)
151 bl schedule_tail
152 cmp r5, #0
153 movne r0, r4
154 badrne lr, 1f
155 retne r5
1561: get_thread_info tsk
157 b ret_slow_syscall
158ENDPROC(ret_from_fork)
159
160/*=============================================================================
161 * SWI handler
162 *-----------------------------------------------------------------------------
163 */
164
165 .align 5
166ENTRY(vector_swi)
167#ifdef CONFIG_CPU_V7M
168 v7m_exception_entry
169#else
170 sub sp, sp, #PT_REGS_SIZE
171 stmia sp, {r0 - r12} @ Calling r0 - r12
172 ARM( add r8, sp, #S_PC )
173 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
174 THUMB( mov r8, sp )
175 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
176 mrs saved_psr, spsr @ called from non-FIQ mode, so ok.
177 TRACE( mov saved_pc, lr )
178 str saved_pc, [sp, #S_PC] @ Save calling PC
179 str saved_psr, [sp, #S_PSR] @ Save CPSR
180 str r0, [sp, #S_OLD_R0] @ Save OLD_R0
181#endif
182 zero_fp
183 alignment_trap r10, ip, __cr_alignment
184 asm_trace_hardirqs_on save=0
185 enable_irq_notrace
186 ct_user_exit save=0
187
188 /*
189 * Get the system call number.
190 */
191
192#if defined(CONFIG_OABI_COMPAT)
193
194 /*
195 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
196 * value to determine if it is an EABI or an old ABI call.
197 */
198#ifdef CONFIG_ARM_THUMB
199 tst saved_psr, #PSR_T_BIT
200 movne r10, #0 @ no thumb OABI emulation
201 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction
202#else
203 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction
204#endif
205 ARM_BE8(rev r10, r10) @ little endian instruction
206
207#elif defined(CONFIG_AEABI)
208
209 /*
210 * Pure EABI user space always put syscall number into scno (r7).
211 */
212#elif defined(CONFIG_ARM_THUMB)
213 /* Legacy ABI only, possibly thumb mode. */
214 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs
215 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
216 USER( ldreq scno, [saved_pc, #-4] )
217
218#else
219 /* Legacy ABI only. */
220 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction
221#endif
222
223 /* saved_psr and saved_pc are now dead */
224
225 uaccess_disable tbl
226
227 adr tbl, sys_call_table @ load syscall table pointer
228
229#if defined(CONFIG_OABI_COMPAT)
230 /*
231 * If the swi argument is zero, this is an EABI call and we do nothing.
232 *
233 * If this is an old ABI call, get the syscall number into scno and
234 * get the old ABI syscall table address.
235 */
236 bics r10, r10, #0xff000000
237 eorne scno, r10, #__NR_OABI_SYSCALL_BASE
238 ldrne tbl, =sys_oabi_call_table
239#elif !defined(CONFIG_AEABI)
240 bic scno, scno, #0xff000000 @ mask off SWI op-code
241 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
242#endif
243 get_thread_info tsk
244 /*
245 * Reload the registers that may have been corrupted on entry to
246 * the syscall assembly (by tracing or context tracking.)
247 */
248 TRACE( ldmia sp, {r0 - r3} )
249
250local_restart:
251 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
252 stmdb sp!, {r4, r5} @ push fifth and sixth args
253
254 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
255 bne __sys_trace
256
257 invoke_syscall tbl, scno, r10, __ret_fast_syscall
258
259 add r1, sp, #S_OFF
2602: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
261 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
262 bcs arm_syscall
263 mov why, #0 @ no longer a real syscall
264 b sys_ni_syscall @ not private func
265
266#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
267 /*
268 * We failed to handle a fault trying to access the page
269 * containing the swi instruction, but we're not really in a
270 * position to return -EFAULT. Instead, return back to the
271 * instruction and re-enter the user fault handling path trying
272 * to page it in. This will likely result in sending SEGV to the
273 * current task.
274 */
2759001:
276 sub lr, saved_pc, #4
277 str lr, [sp, #S_PC]
278 get_thread_info tsk
279 b ret_fast_syscall
280#endif
281ENDPROC(vector_swi)
282
283 /*
284 * This is the really slow path. We're going to be doing
285 * context switches, and waiting for our parent to respond.
286 */
287__sys_trace:
288 mov r1, scno
289 add r0, sp, #S_OFF
290 bl syscall_trace_enter
291 mov scno, r0
292 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
293 cmp scno, #-1 @ skip the syscall?
294 bne 2b
295 add sp, sp, #S_OFF @ restore stack
296
297__sys_trace_return_nosave:
298 enable_irq_notrace
299 mov r0, sp
300 bl syscall_trace_exit
301 b ret_slow_syscall
302
303__sys_trace_return:
304 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
305 mov r0, sp
306 bl syscall_trace_exit
307 b ret_slow_syscall
308
309 .align 5
310#ifdef CONFIG_ALIGNMENT_TRAP
311 .type __cr_alignment, #object
312__cr_alignment:
313 .word cr_alignment
314#endif
315 .ltorg
316
317 .macro syscall_table_start, sym
318 .equ __sys_nr, 0
319 .type \sym, #object
320ENTRY(\sym)
321 .endm
322
323 .macro syscall, nr, func
324 .ifgt __sys_nr - \nr
325 .error "Duplicated/unorded system call entry"
326 .endif
327 .rept \nr - __sys_nr
328 .long sys_ni_syscall
329 .endr
330 .long \func
331 .equ __sys_nr, \nr + 1
332 .endm
333
334 .macro syscall_table_end, sym
335 .ifgt __sys_nr - __NR_syscalls
336 .error "System call table too big"
337 .endif
338 .rept __NR_syscalls - __sys_nr
339 .long sys_ni_syscall
340 .endr
341 .size \sym, . - \sym
342 .endm
343
344#define NATIVE(nr, func) syscall nr, func
345
346/*
347 * This is the syscall table declaration for native ABI syscalls.
348 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
349 */
350 syscall_table_start sys_call_table
351#define COMPAT(nr, native, compat) syscall nr, native
352#ifdef CONFIG_AEABI
353#include <calls-eabi.S>
354#else
355#include <calls-oabi.S>
356#endif
357#undef COMPAT
358 syscall_table_end sys_call_table
359
360/*============================================================================
361 * Special system call wrappers
362 */
363@ r0 = syscall number
364@ r8 = syscall table
365sys_syscall:
366 bic scno, r0, #__NR_OABI_SYSCALL_BASE
367 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
368 cmpne scno, #NR_syscalls @ check range
369#ifdef CONFIG_CPU_SPECTRE
370 movhs scno, #0
371 csdb
372#endif
373 stmialo sp, {r5, r6} @ shuffle args
374 movlo r0, r1
375 movlo r1, r2
376 movlo r2, r3
377 movlo r3, r4
378 ldrlo pc, [tbl, scno, lsl #2]
379 b sys_ni_syscall
380ENDPROC(sys_syscall)
381
382sys_sigreturn_wrapper:
383 add r0, sp, #S_OFF
384 mov why, #0 @ prevent syscall restart handling
385 b sys_sigreturn
386ENDPROC(sys_sigreturn_wrapper)
387
388sys_rt_sigreturn_wrapper:
389 add r0, sp, #S_OFF
390 mov why, #0 @ prevent syscall restart handling
391 b sys_rt_sigreturn
392ENDPROC(sys_rt_sigreturn_wrapper)
393
394sys_statfs64_wrapper:
395 teq r1, #88
396 moveq r1, #84
397 b sys_statfs64
398ENDPROC(sys_statfs64_wrapper)
399
400sys_fstatfs64_wrapper:
401 teq r1, #88
402 moveq r1, #84
403 b sys_fstatfs64
404ENDPROC(sys_fstatfs64_wrapper)
405
406/*
407 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
408 * offset, we return EINVAL.
409 */
410sys_mmap2:
411 str r5, [sp, #4]
412 b sys_mmap_pgoff
413ENDPROC(sys_mmap2)
414
415#ifdef CONFIG_OABI_COMPAT
416
417/*
418 * These are syscalls with argument register differences
419 */
420
421sys_oabi_pread64:
422 stmia sp, {r3, r4}
423 b sys_pread64
424ENDPROC(sys_oabi_pread64)
425
426sys_oabi_pwrite64:
427 stmia sp, {r3, r4}
428 b sys_pwrite64
429ENDPROC(sys_oabi_pwrite64)
430
431sys_oabi_truncate64:
432 mov r3, r2
433 mov r2, r1
434 b sys_truncate64
435ENDPROC(sys_oabi_truncate64)
436
437sys_oabi_ftruncate64:
438 mov r3, r2
439 mov r2, r1
440 b sys_ftruncate64
441ENDPROC(sys_oabi_ftruncate64)
442
443sys_oabi_readahead:
444 str r3, [sp]
445 mov r3, r2
446 mov r2, r1
447 b sys_readahead
448ENDPROC(sys_oabi_readahead)
449
450/*
451 * Let's declare a second syscall table for old ABI binaries
452 * using the compatibility syscall entries.
453 */
454 syscall_table_start sys_oabi_call_table
455#define COMPAT(nr, native, compat) syscall nr, compat
456#include <calls-oabi.S>
457 syscall_table_end sys_oabi_call_table
458
459#endif
460