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
461