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	ldr	r1, =TASK_SIZE
54	cmp	r2, r1
55	blne	addr_limit_check_failed
56	ldr	r1, [tsk, #TI_FLAGS]		@ re-check for syscall tracing
57	movs	r1, r1, lsl #16
58	bne	fast_work_pending
59
60
61	/* perform architecture specific actions before user return */
62	arch_ret_to_user r1, lr
63
64	restore_user_regs fast = 1, offset = S_OFF
65 UNWIND(.fnend		)
66ENDPROC(ret_fast_syscall)
67
68	/* Ok, we need to do extra processing, enter the slow path. */
69fast_work_pending:
70	str	r0, [sp, #S_R0+S_OFF]!		@ returned r0
71	/* fall through to work_pending */
72#else
73/*
74 * The "replacement" ret_fast_syscall for when tracing, context tracking,
75 * or rseq debug is enabled.  As we will need to call out to some C functions,
76 * we save r0 first to avoid needing to save registers around each C function
77 * call.
78 */
79ret_fast_syscall:
80__ret_fast_syscall:
81 UNWIND(.fnstart	)
82 UNWIND(.cantunwind	)
83	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
84#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
85	/* do_rseq_syscall needs interrupts enabled. */
86	mov	r0, sp				@ 'regs'
87	bl	do_rseq_syscall
88#endif
89	disable_irq_notrace			@ disable interrupts
90	ldr	r2, [tsk, #TI_ADDR_LIMIT]
91	ldr     r1, =TASK_SIZE
92	cmp     r2, r1
93	blne	addr_limit_check_failed
94	ldr	r1, [tsk, #TI_FLAGS]		@ re-check for syscall tracing
95	movs	r1, r1, lsl #16
96	beq	no_work_pending
97 UNWIND(.fnend		)
98ENDPROC(ret_fast_syscall)
99
100	/* Slower path - fall through to work_pending */
101#endif
102
103	tst	r1, #_TIF_SYSCALL_WORK
104	bne	__sys_trace_return_nosave
105slow_work_pending:
106	mov	r0, sp				@ 'regs'
107	mov	r2, why				@ 'syscall'
108	bl	do_work_pending
109	cmp	r0, #0
110	beq	no_work_pending
111	movlt	scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
112	ldmia	sp, {r0 - r6}			@ have to reload r0 - r6
113	b	local_restart			@ ... and off we go
114ENDPROC(ret_fast_syscall)
115
116/*
117 * "slow" syscall return path.  "why" tells us if this was a real syscall.
118 * IRQs may be enabled here, so always disable them.  Note that we use the
119 * "notrace" version to avoid calling into the tracing code unnecessarily.
120 * do_work_pending() will update this state if necessary.
121 */
122ENTRY(ret_to_user)
123ret_slow_syscall:
124#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
125	/* do_rseq_syscall needs interrupts enabled. */
126	enable_irq_notrace			@ enable interrupts
127	mov	r0, sp				@ 'regs'
128	bl	do_rseq_syscall
129#endif
130	disable_irq_notrace			@ disable interrupts
131ENTRY(ret_to_user_from_irq)
132	ldr	r2, [tsk, #TI_ADDR_LIMIT]
133	ldr     r1, =TASK_SIZE
134	cmp	r2, r1
135	blne	addr_limit_check_failed
136	ldr	r1, [tsk, #TI_FLAGS]
137	movs	r1, r1, lsl #16
138	bne	slow_work_pending
139no_work_pending:
140	asm_trace_hardirqs_on save = 0
141
142	/* perform architecture specific actions before user return */
143	arch_ret_to_user r1, lr
144	ct_user_enter save = 0
145
146	restore_user_regs fast = 0, offset = 0
147ENDPROC(ret_to_user_from_irq)
148ENDPROC(ret_to_user)
149
150/*
151 * This is how we return from a fork.
152 */
153ENTRY(ret_from_fork)
154	bl	schedule_tail
155	cmp	r5, #0
156	movne	r0, r4
157	badrne	lr, 1f
158	retne	r5
1591:	get_thread_info tsk
160	b	ret_slow_syscall
161ENDPROC(ret_from_fork)
162
163/*=============================================================================
164 * SWI handler
165 *-----------------------------------------------------------------------------
166 */
167
168	.align	5
169ENTRY(vector_swi)
170#ifdef CONFIG_CPU_V7M
171	v7m_exception_entry
172#else
173	sub	sp, sp, #PT_REGS_SIZE
174	stmia	sp, {r0 - r12}			@ Calling r0 - r12
175 ARM(	add	r8, sp, #S_PC		)
176 ARM(	stmdb	r8, {sp, lr}^		)	@ Calling sp, lr
177 THUMB(	mov	r8, sp			)
178 THUMB(	store_user_sp_lr r8, r10, S_SP	)	@ calling sp, lr
179	mrs	saved_psr, spsr			@ called from non-FIQ mode, so ok.
180 TRACE(	mov	saved_pc, lr		)
181	str	saved_pc, [sp, #S_PC]		@ Save calling PC
182	str	saved_psr, [sp, #S_PSR]		@ Save CPSR
183	str	r0, [sp, #S_OLD_R0]		@ Save OLD_R0
184#endif
185	zero_fp
186	alignment_trap r10, ip, __cr_alignment
187	asm_trace_hardirqs_on save=0
188	enable_irq_notrace
189	ct_user_exit save=0
190
191	/*
192	 * Get the system call number.
193	 */
194
195#if defined(CONFIG_OABI_COMPAT)
196
197	/*
198	 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
199	 * value to determine if it is an EABI or an old ABI call.
200	 */
201#ifdef CONFIG_ARM_THUMB
202	tst	saved_psr, #PSR_T_BIT
203	movne	r10, #0				@ no thumb OABI emulation
204 USER(	ldreq	r10, [saved_pc, #-4]	)	@ get SWI instruction
205#else
206 USER(	ldr	r10, [saved_pc, #-4]	)	@ get SWI instruction
207#endif
208 ARM_BE8(rev	r10, r10)			@ little endian instruction
209
210#elif defined(CONFIG_AEABI)
211
212	/*
213	 * Pure EABI user space always put syscall number into scno (r7).
214	 */
215#elif defined(CONFIG_ARM_THUMB)
216	/* Legacy ABI only, possibly thumb mode. */
217	tst	saved_psr, #PSR_T_BIT		@ this is SPSR from save_user_regs
218	addne	scno, r7, #__NR_SYSCALL_BASE	@ put OS number in
219 USER(	ldreq	scno, [saved_pc, #-4]	)
220
221#else
222	/* Legacy ABI only. */
223 USER(	ldr	scno, [saved_pc, #-4]	)	@ get SWI instruction
224#endif
225
226	/* saved_psr and saved_pc are now dead */
227
228	uaccess_disable tbl
229
230	adr	tbl, sys_call_table		@ load syscall table pointer
231
232#if defined(CONFIG_OABI_COMPAT)
233	/*
234	 * If the swi argument is zero, this is an EABI call and we do nothing.
235	 *
236	 * If this is an old ABI call, get the syscall number into scno and
237	 * get the old ABI syscall table address.
238	 */
239	bics	r10, r10, #0xff000000
240	eorne	scno, r10, #__NR_OABI_SYSCALL_BASE
241	ldrne	tbl, =sys_oabi_call_table
242#elif !defined(CONFIG_AEABI)
243	bic	scno, scno, #0xff000000		@ mask off SWI op-code
244	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number
245#endif
246	get_thread_info tsk
247	/*
248	 * Reload the registers that may have been corrupted on entry to
249	 * the syscall assembly (by tracing or context tracking.)
250	 */
251 TRACE(	ldmia	sp, {r0 - r3}		)
252
253local_restart:
254	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing
255	stmdb	sp!, {r4, r5}			@ push fifth and sixth args
256
257	tst	r10, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
258	bne	__sys_trace
259
260	invoke_syscall tbl, scno, r10, __ret_fast_syscall
261
262	add	r1, sp, #S_OFF
2632:	cmp	scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
264	eor	r0, scno, #__NR_SYSCALL_BASE	@ put OS number back
265	bcs	arm_syscall
266	mov	why, #0				@ no longer a real syscall
267	b	sys_ni_syscall			@ not private func
268
269#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
270	/*
271	 * We failed to handle a fault trying to access the page
272	 * containing the swi instruction, but we're not really in a
273	 * position to return -EFAULT. Instead, return back to the
274	 * instruction and re-enter the user fault handling path trying
275	 * to page it in. This will likely result in sending SEGV to the
276	 * current task.
277	 */
2789001:
279	sub	lr, saved_pc, #4
280	str	lr, [sp, #S_PC]
281	get_thread_info tsk
282	b	ret_fast_syscall
283#endif
284ENDPROC(vector_swi)
285
286	/*
287	 * This is the really slow path.  We're going to be doing
288	 * context switches, and waiting for our parent to respond.
289	 */
290__sys_trace:
291	mov	r1, scno
292	add	r0, sp, #S_OFF
293	bl	syscall_trace_enter
294	mov	scno, r0
295	invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
296	cmp	scno, #-1			@ skip the syscall?
297	bne	2b
298	add	sp, sp, #S_OFF			@ restore stack
299
300__sys_trace_return_nosave:
301	enable_irq_notrace
302	mov	r0, sp
303	bl	syscall_trace_exit
304	b	ret_slow_syscall
305
306__sys_trace_return:
307	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
308	mov	r0, sp
309	bl	syscall_trace_exit
310	b	ret_slow_syscall
311
312	.align	5
313#ifdef CONFIG_ALIGNMENT_TRAP
314	.type	__cr_alignment, #object
315__cr_alignment:
316	.word	cr_alignment
317#endif
318	.ltorg
319
320	.macro	syscall_table_start, sym
321	.equ	__sys_nr, 0
322	.type	\sym, #object
323ENTRY(\sym)
324	.endm
325
326	.macro	syscall, nr, func
327	.ifgt	__sys_nr - \nr
328	.error	"Duplicated/unorded system call entry"
329	.endif
330	.rept	\nr - __sys_nr
331	.long	sys_ni_syscall
332	.endr
333	.long	\func
334	.equ	__sys_nr, \nr + 1
335	.endm
336
337	.macro	syscall_table_end, sym
338	.ifgt	__sys_nr - __NR_syscalls
339	.error	"System call table too big"
340	.endif
341	.rept	__NR_syscalls - __sys_nr
342	.long	sys_ni_syscall
343	.endr
344	.size	\sym, . - \sym
345	.endm
346
347#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, native)
348#define __SYSCALL(nr, func) syscall nr, func
349
350/*
351 * This is the syscall table declaration for native ABI syscalls.
352 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
353 */
354	syscall_table_start sys_call_table
355#ifdef CONFIG_AEABI
356#include <calls-eabi.S>
357#else
358#include <calls-oabi.S>
359#endif
360	syscall_table_end sys_call_table
361
362/*============================================================================
363 * Special system call wrappers
364 */
365@ r0 = syscall number
366@ r8 = syscall table
367sys_syscall:
368		bic	scno, r0, #__NR_OABI_SYSCALL_BASE
369		cmp	scno, #__NR_syscall - __NR_SYSCALL_BASE
370		cmpne	scno, #NR_syscalls	@ check range
371#ifdef CONFIG_CPU_SPECTRE
372		movhs	scno, #0
373		csdb
374#endif
375		stmialo	sp, {r5, r6}		@ shuffle args
376		movlo	r0, r1
377		movlo	r1, r2
378		movlo	r2, r3
379		movlo	r3, r4
380		ldrlo	pc, [tbl, scno, lsl #2]
381		b	sys_ni_syscall
382ENDPROC(sys_syscall)
383
384sys_sigreturn_wrapper:
385		add	r0, sp, #S_OFF
386		mov	why, #0		@ prevent syscall restart handling
387		b	sys_sigreturn
388ENDPROC(sys_sigreturn_wrapper)
389
390sys_rt_sigreturn_wrapper:
391		add	r0, sp, #S_OFF
392		mov	why, #0		@ prevent syscall restart handling
393		b	sys_rt_sigreturn
394ENDPROC(sys_rt_sigreturn_wrapper)
395
396sys_statfs64_wrapper:
397		teq	r1, #88
398		moveq	r1, #84
399		b	sys_statfs64
400ENDPROC(sys_statfs64_wrapper)
401
402sys_fstatfs64_wrapper:
403		teq	r1, #88
404		moveq	r1, #84
405		b	sys_fstatfs64
406ENDPROC(sys_fstatfs64_wrapper)
407
408/*
409 * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
410 * offset, we return EINVAL.
411 */
412sys_mmap2:
413		str	r5, [sp, #4]
414		b	sys_mmap_pgoff
415ENDPROC(sys_mmap2)
416
417#ifdef CONFIG_OABI_COMPAT
418
419/*
420 * These are syscalls with argument register differences
421 */
422
423sys_oabi_pread64:
424		stmia	sp, {r3, r4}
425		b	sys_pread64
426ENDPROC(sys_oabi_pread64)
427
428sys_oabi_pwrite64:
429		stmia	sp, {r3, r4}
430		b	sys_pwrite64
431ENDPROC(sys_oabi_pwrite64)
432
433sys_oabi_truncate64:
434		mov	r3, r2
435		mov	r2, r1
436		b	sys_truncate64
437ENDPROC(sys_oabi_truncate64)
438
439sys_oabi_ftruncate64:
440		mov	r3, r2
441		mov	r2, r1
442		b	sys_ftruncate64
443ENDPROC(sys_oabi_ftruncate64)
444
445sys_oabi_readahead:
446		str	r3, [sp]
447		mov	r3, r2
448		mov	r2, r1
449		b	sys_readahead
450ENDPROC(sys_oabi_readahead)
451
452/*
453 * Let's declare a second syscall table for old ABI binaries
454 * using the compatibility syscall entries.
455 */
456	syscall_table_start sys_oabi_call_table
457#undef __SYSCALL_WITH_COMPAT
458#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, compat)
459#include <calls-oabi.S>
460	syscall_table_end sys_oabi_call_table
461
462#endif
463
464