[linux-2.6-block.git] / arch / arm / kernel / entry-common.S

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 *  linux/arch/arm/kernel/entry-common.S
 *
 *  Copyright (C) 2000 Russell King
 */

#include <asm/assembler.h>
#include <asm/unistd.h>
#include <asm/ftrace.h>
#include <asm/unwind.h>
#include <asm/page.h>
#ifdef CONFIG_AEABI
#include <asm/unistd-oabi.h>
#endif

	.equ	NR_syscalls, __NR_syscalls

#include "entry-header.S"

saved_psr	.req	r8
#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING_USER)
saved_pc	.req	r9
#define TRACE(x...) x
#else
saved_pc	.req	lr
#define TRACE(x...)
#endif

	.section .entry.text,"ax",%progbits
	.align	5
#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING_USER) || \
	IS_ENABLED(CONFIG_DEBUG_RSEQ))
/*
 * This is the fast syscall return path.  We do as little as possible here,
 * such as avoiding writing r0 to the stack.  We only use this path if we
 * have tracing, context tracking and rseq debug disabled - the overheads
 * from those features make this path too inefficient.
 */
ret_fast_syscall:
__ret_fast_syscall:
 UNWIND(.fnstart	)
 UNWIND(.cantunwind	)
	disable_irq_notrace			@ disable interrupts
	ldr	r1, [tsk, #TI_FLAGS]		@ re-check for syscall tracing
	movs	r1, r1, lsl #16
	bne	fast_work_pending

	restore_user_regs fast = 1, offset = S_OFF
 UNWIND(.fnend		)
ENDPROC(ret_fast_syscall)

	/* Ok, we need to do extra processing, enter the slow path. */
fast_work_pending:
	str	r0, [sp, #S_R0+S_OFF]!		@ returned r0
	/* fall through to work_pending */
#else
/*
 * The "replacement" ret_fast_syscall for when tracing, context tracking,
 * or rseq debug is enabled.  As we will need to call out to some C functions,
 * we save r0 first to avoid needing to save registers around each C function
 * call.
 */
ret_fast_syscall:
__ret_fast_syscall:
 UNWIND(.fnstart	)
 UNWIND(.cantunwind	)
	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
	/* do_rseq_syscall needs interrupts enabled. */
	mov	r0, sp				@ 'regs'
	bl	do_rseq_syscall
#endif
	disable_irq_notrace			@ disable interrupts
	ldr	r1, [tsk, #TI_FLAGS]		@ re-check for syscall tracing
	movs	r1, r1, lsl #16
	beq	no_work_pending
 UNWIND(.fnend		)
ENDPROC(ret_fast_syscall)

	/* Slower path - fall through to work_pending */
#endif

	tst	r1, #_TIF_SYSCALL_WORK
	bne	__sys_trace_return_nosave
slow_work_pending:
	mov	r0, sp				@ 'regs'
	mov	r2, why				@ 'syscall'
	bl	do_work_pending
	cmp	r0, #0
	beq	no_work_pending
	movlt	scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
	str	scno, [tsk, #TI_ABI_SYSCALL]	@ make sure tracers see update
	ldmia	sp, {r0 - r6}			@ have to reload r0 - r6
	b	local_restart			@ ... and off we go
ENDPROC(ret_fast_syscall)

/*
 * "slow" syscall return path.  "why" tells us if this was a real syscall.
 * IRQs may be enabled here, so always disable them.  Note that we use the
 * "notrace" version to avoid calling into the tracing code unnecessarily.
 * do_work_pending() will update this state if necessary.
 */
ENTRY(ret_to_user)
ret_slow_syscall:
#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
	/* do_rseq_syscall needs interrupts enabled. */
	enable_irq_notrace			@ enable interrupts
	mov	r0, sp				@ 'regs'
	bl	do_rseq_syscall
#endif
	disable_irq_notrace			@ disable interrupts
ENTRY(ret_to_user_from_irq)
	ldr	r1, [tsk, #TI_FLAGS]
	movs	r1, r1, lsl #16
	bne	slow_work_pending
no_work_pending:
	asm_trace_hardirqs_on save = 0

	ct_user_enter save = 0

#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
	bl	stackleak_erase_on_task_stack
#endif
	restore_user_regs fast = 0, offset = 0
ENDPROC(ret_to_user_from_irq)
ENDPROC(ret_to_user)

/*
 * This is how we return from a fork.
 */
ENTRY(ret_from_fork)
	bl	schedule_tail
	cmp	r5, #0
	movne	r0, r4
	badrne	lr, 1f
	retne	r5
1:	get_thread_info tsk
	b	ret_slow_syscall
ENDPROC(ret_from_fork)

/*=============================================================================
 * SWI handler
 *-----------------------------------------------------------------------------
 */

	.align	5
#ifdef CONFIG_HARDEN_BRANCH_HISTORY
ENTRY(vector_bhb_loop8_swi)
	sub	sp, sp, #PT_REGS_SIZE
	stmia	sp, {r0 - r12}
	mov	r8, #8
1:	b	2f
2:	subs	r8, r8, #1
	bne	1b
	dsb	nsh
	isb
	b	3f
ENDPROC(vector_bhb_loop8_swi)

	.align	5
ENTRY(vector_bhb_bpiall_swi)
	sub	sp, sp, #PT_REGS_SIZE
	stmia	sp, {r0 - r12}
	mcr	p15, 0, r8, c7, c5, 6	@ BPIALL
	isb
	b	3f
ENDPROC(vector_bhb_bpiall_swi)
#endif
	.align	5
ENTRY(vector_swi)
#ifdef CONFIG_CPU_V7M
	v7m_exception_entry
#else
	sub	sp, sp, #PT_REGS_SIZE
	stmia	sp, {r0 - r12}			@ Calling r0 - r12
3:
 ARM(	add	r8, sp, #S_PC		)
 ARM(	stmdb	r8, {sp, lr}^		)	@ Calling sp, lr
 THUMB(	mov	r8, sp			)
 THUMB(	store_user_sp_lr r8, r10, S_SP	)	@ calling sp, lr
	mrs	saved_psr, spsr			@ called from non-FIQ mode, so ok.
 TRACE(	mov	saved_pc, lr		)
	str	saved_pc, [sp, #S_PC]		@ Save calling PC
	str	saved_psr, [sp, #S_PSR]		@ Save CPSR
	str	r0, [sp, #S_OLD_R0]		@ Save OLD_R0
#endif
	reload_current r10, ip
	zero_fp
	alignment_trap r10, ip, cr_alignment
	asm_trace_hardirqs_on save=0
	enable_irq_notrace
	ct_user_exit save=0

	/*
	 * Get the system call number.
	 */

#if defined(CONFIG_OABI_COMPAT)

	/*
	 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
	 * value to determine if it is an EABI or an old ABI call.
	 */
#ifdef CONFIG_ARM_THUMB
	tst	saved_psr, #PSR_T_BIT
	movne	r10, #0				@ no thumb OABI emulation
 USER(	ldreq	r10, [saved_pc, #-4]	)	@ get SWI instruction
#else
 USER(	ldr	r10, [saved_pc, #-4]	)	@ get SWI instruction
#endif
 ARM_BE8(rev	r10, r10)			@ little endian instruction

#elif defined(CONFIG_AEABI)

	/*
	 * Pure EABI user space always put syscall number into scno (r7).
	 */
#elif defined(CONFIG_ARM_THUMB)
	/* Legacy ABI only, possibly thumb mode. */
	tst	saved_psr, #PSR_T_BIT		@ this is SPSR from save_user_regs
	addne	scno, r7, #__NR_SYSCALL_BASE	@ put OS number in
 USER(	ldreq	scno, [saved_pc, #-4]	)

#else
	/* Legacy ABI only. */
 USER(	ldr	scno, [saved_pc, #-4]	)	@ get SWI instruction
#endif

	/* saved_psr and saved_pc are now dead */

	uaccess_disable tbl
	get_thread_info tsk

	adr	tbl, sys_call_table		@ load syscall table pointer

#if defined(CONFIG_OABI_COMPAT)
	/*
	 * If the swi argument is zero, this is an EABI call and we do nothing.
	 *
	 * If this is an old ABI call, get the syscall number into scno and
	 * get the old ABI syscall table address.
	 */
	bics	r10, r10, #0xff000000
	strne	r10, [tsk, #TI_ABI_SYSCALL]
	streq	scno, [tsk, #TI_ABI_SYSCALL]
	eorne	scno, r10, #__NR_OABI_SYSCALL_BASE
	ldrne	tbl, =sys_oabi_call_table
#elif !defined(CONFIG_AEABI)
	bic	scno, scno, #0xff000000		@ mask off SWI op-code
	str	scno, [tsk, #TI_ABI_SYSCALL]
	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number
#else
	str	scno, [tsk, #TI_ABI_SYSCALL]
#endif
	/*
	 * Reload the registers that may have been corrupted on entry to
	 * the syscall assembly (by tracing or context tracking.)
	 */
 TRACE(	ldmia	sp, {r0 - r3}		)

local_restart:
	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing
	stmdb	sp!, {r4, r5}			@ push fifth and sixth args

	tst	r10, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
	bne	__sys_trace

	invoke_syscall tbl, scno, r10, __ret_fast_syscall

	add	r1, sp, #S_OFF
2:	cmp	scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
	eor	r0, scno, #__NR_SYSCALL_BASE	@ put OS number back
	bcs	arm_syscall
	mov	why, #0				@ no longer a real syscall
	b	sys_ni_syscall			@ not private func

#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
	/*
	 * We failed to handle a fault trying to access the page
	 * containing the swi instruction, but we're not really in a
	 * position to return -EFAULT. Instead, return back to the
	 * instruction and re-enter the user fault handling path trying
	 * to page it in. This will likely result in sending SEGV to the
	 * current task.
	 */
9001:
	sub	lr, saved_pc, #4
	str	lr, [sp, #S_PC]
	get_thread_info tsk
	b	ret_fast_syscall
#endif
ENDPROC(vector_swi)
	.ltorg

	/*
	 * This is the really slow path.  We're going to be doing
	 * context switches, and waiting for our parent to respond.
	 */
__sys_trace:
	add	r0, sp, #S_OFF
	bl	syscall_trace_enter
	mov	scno, r0
	invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
	cmp	scno, #-1			@ skip the syscall?
	bne	2b
	add	sp, sp, #S_OFF			@ restore stack

__sys_trace_return_nosave:
	enable_irq_notrace
	mov	r0, sp
	bl	syscall_trace_exit
	b	ret_slow_syscall

__sys_trace_return:
	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
	mov	r0, sp
	bl	syscall_trace_exit
	b	ret_slow_syscall

	.macro	syscall_table_start, sym
	.equ	__sys_nr, 0
	.type	\sym, #object
ENTRY(\sym)
	.endm

	.macro	syscall, nr, func
	.ifgt	__sys_nr - \nr
	.error	"Duplicated/unorded system call entry"
	.endif
	.rept	\nr - __sys_nr
	.long	sys_ni_syscall
	.endr
	.long	\func
	.equ	__sys_nr, \nr + 1
	.endm

	.macro	syscall_table_end, sym
	.ifgt	__sys_nr - __NR_syscalls
	.error	"System call table too big"
	.endif
	.rept	__NR_syscalls - __sys_nr
	.long	sys_ni_syscall
	.endr
	.size	\sym, . - \sym
	.endm

#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, native)
#define __SYSCALL(nr, func) syscall nr, func

/*
 * This is the syscall table declaration for native ABI syscalls.
 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
 */
	syscall_table_start sys_call_table
#ifdef CONFIG_AEABI
#include <calls-eabi.S>
#else
#include <calls-oabi.S>
#endif
	syscall_table_end sys_call_table

/*============================================================================
 * Special system call wrappers
 */
@ r0 = syscall number
@ r8 = syscall table
sys_syscall:
		bic	scno, r0, #__NR_OABI_SYSCALL_BASE
		cmp	scno, #__NR_syscall - __NR_SYSCALL_BASE
		cmpne	scno, #NR_syscalls	@ check range
#ifdef CONFIG_CPU_SPECTRE
		movhs	scno, #0
		csdb
#endif
		stmialo	sp, {r5, r6}		@ shuffle args
		movlo	r0, r1
		movlo	r1, r2
		movlo	r2, r3
		movlo	r3, r4
		ldrlo	pc, [tbl, scno, lsl #2]
		b	sys_ni_syscall
ENDPROC(sys_syscall)

sys_sigreturn_wrapper:
		add	r0, sp, #S_OFF
		mov	why, #0		@ prevent syscall restart handling
		b	sys_sigreturn
ENDPROC(sys_sigreturn_wrapper)

sys_rt_sigreturn_wrapper:
		add	r0, sp, #S_OFF
		mov	why, #0		@ prevent syscall restart handling
		b	sys_rt_sigreturn
ENDPROC(sys_rt_sigreturn_wrapper)

sys_statfs64_wrapper:
		teq	r1, #88
		moveq	r1, #84
		b	sys_statfs64
ENDPROC(sys_statfs64_wrapper)

sys_fstatfs64_wrapper:
		teq	r1, #88
		moveq	r1, #84
		b	sys_fstatfs64
ENDPROC(sys_fstatfs64_wrapper)

/*
 * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
 * offset, we return EINVAL.
 */
sys_mmap2:
		str	r5, [sp, #4]
		b	sys_mmap_pgoff
ENDPROC(sys_mmap2)

#ifdef CONFIG_OABI_COMPAT

/*
 * These are syscalls with argument register differences
 */

sys_oabi_pread64:
		stmia	sp, {r3, r4}
		b	sys_pread64
ENDPROC(sys_oabi_pread64)

sys_oabi_pwrite64:
		stmia	sp, {r3, r4}
		b	sys_pwrite64
ENDPROC(sys_oabi_pwrite64)

sys_oabi_truncate64:
		mov	r3, r2
		mov	r2, r1
		b	sys_truncate64
ENDPROC(sys_oabi_truncate64)

sys_oabi_ftruncate64:
		mov	r3, r2
		mov	r2, r1
		b	sys_ftruncate64
ENDPROC(sys_oabi_ftruncate64)

sys_oabi_readahead:
		str	r3, [sp]
		mov	r3, r2
		mov	r2, r1
		b	sys_readahead
ENDPROC(sys_oabi_readahead)

/*
 * Let's declare a second syscall table for old ABI binaries
 * using the compatibility syscall entries.
 */
	syscall_table_start sys_oabi_call_table
#undef __SYSCALL_WITH_COMPAT
#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, compat)
#include <calls-oabi.S>
	syscall_table_end sys_oabi_call_table

#endif
Commit	Line	Data
	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/page.h>
	13	#ifdef CONFIG_AEABI
	14	#include <asm/unistd-oabi.h>
	15	#endif
	16
	17	.equ NR_syscalls, __NR_syscalls
	18
	19	#include "entry-header.S"
	20
	21	saved_psr .req r8
	22	#if defined(CONFIG_TRACE_IRQFLAGS) \|\| defined(CONFIG_CONTEXT_TRACKING_USER)
	23	saved_pc .req r9
	24	#define TRACE(x...) x
	25	#else
	26	saved_pc .req lr
	27	#define TRACE(x...)
	28	#endif
	29
	30	.section .entry.text,"ax",%progbits
	31	.align 5
	32	#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) \|\| IS_ENABLED(CONFIG_CONTEXT_TRACKING_USER) \|\| \
	33	IS_ENABLED(CONFIG_DEBUG_RSEQ))
	34	/*
	35	* This is the fast syscall return path. We do as little as possible here,
	36	* such as avoiding writing r0 to the stack. We only use this path if we
	37	* have tracing, context tracking and rseq debug disabled - the overheads
	38	* from those features make this path too inefficient.
	39	*/
	40	ret_fast_syscall:
	41	__ret_fast_syscall:
	42	UNWIND(.fnstart )
	43	UNWIND(.cantunwind )
	44	disable_irq_notrace @ disable interrupts
	45	ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
	46	movs r1, r1, lsl #16
	47	bne fast_work_pending
	48
	49	restore_user_regs fast = 1, offset = S_OFF
	50	UNWIND(.fnend )
	51	ENDPROC(ret_fast_syscall)
	52
	53	/* Ok, we need to do extra processing, enter the slow path. */
	54	fast_work_pending:
	55	str r0, [sp, #S_R0+S_OFF]! @ returned r0
	56	/* fall through to work_pending */
	57	#else
	58	/*
	59	* The "replacement" ret_fast_syscall for when tracing, context tracking,
	60	* or rseq debug is enabled. As we will need to call out to some C functions,
	61	* we save r0 first to avoid needing to save registers around each C function
	62	* call.
	63	*/
	64	ret_fast_syscall:
	65	__ret_fast_syscall:
	66	UNWIND(.fnstart )
	67	UNWIND(.cantunwind )
	68	str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
	69	#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
	70	/* do_rseq_syscall needs interrupts enabled. */
	71	mov r0, sp @ 'regs'
	72	bl do_rseq_syscall
	73	#endif
	74	disable_irq_notrace @ disable interrupts
	75	ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
	76	movs r1, r1, lsl #16
	77	beq no_work_pending
	78	UNWIND(.fnend )
	79	ENDPROC(ret_fast_syscall)
	80
	81	/* Slower path - fall through to work_pending */
	82	#endif
	83
	84	tst r1, #_TIF_SYSCALL_WORK
	85	bne __sys_trace_return_nosave
	86	slow_work_pending:
	87	mov r0, sp @ 'regs'
	88	mov r2, why @ 'syscall'
	89	bl do_work_pending
	90	cmp r0, #0
	91	beq no_work_pending
	92	movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
	93	str scno, [tsk, #TI_ABI_SYSCALL] @ make sure tracers see update
	94	ldmia sp, {r0 - r6} @ have to reload r0 - r6
	95	b local_restart @ ... and off we go
	96	ENDPROC(ret_fast_syscall)
	97
	98	/*
	99	* "slow" syscall return path. "why" tells us if this was a real syscall.
	100	* IRQs may be enabled here, so always disable them. Note that we use the
	101	* "notrace" version to avoid calling into the tracing code unnecessarily.
	102	* do_work_pending() will update this state if necessary.
	103	*/
	104	ENTRY(ret_to_user)
	105	ret_slow_syscall:
	106	#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
	107	/* do_rseq_syscall needs interrupts enabled. */
	108	enable_irq_notrace @ enable interrupts
	109	mov r0, sp @ 'regs'
	110	bl do_rseq_syscall
	111	#endif
	112	disable_irq_notrace @ disable interrupts
	113	ENTRY(ret_to_user_from_irq)
	114	ldr r1, [tsk, #TI_FLAGS]
	115	movs r1, r1, lsl #16
	116	bne slow_work_pending
	117	no_work_pending:
	118	asm_trace_hardirqs_on save = 0
	119
	120	ct_user_enter save = 0
	121
	122	#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
	123	bl stackleak_erase_on_task_stack
	124	#endif
	125	restore_user_regs fast = 0, offset = 0
	126	ENDPROC(ret_to_user_from_irq)
	127	ENDPROC(ret_to_user)
	128
	129	/*
	130	* This is how we return from a fork.
	131	*/
	132	ENTRY(ret_from_fork)
	133	bl schedule_tail
	134	cmp r5, #0
	135	movne r0, r4
	136	badrne lr, 1f
	137	retne r5
	138	1: get_thread_info tsk
	139	b ret_slow_syscall
	140	ENDPROC(ret_from_fork)
	141
	142	/*=============================================================================
	143	* SWI handler
	144	*-----------------------------------------------------------------------------
	145	*/
	146
	147	.align 5
	148	#ifdef CONFIG_HARDEN_BRANCH_HISTORY
	149	ENTRY(vector_bhb_loop8_swi)
	150	sub sp, sp, #PT_REGS_SIZE
	151	stmia sp, {r0 - r12}
	152	mov r8, #8
	153	1: b 2f
	154	2: subs r8, r8, #1
	155	bne 1b
	156	dsb nsh
	157	isb
	158	b 3f
	159	ENDPROC(vector_bhb_loop8_swi)
	160
	161	.align 5
	162	ENTRY(vector_bhb_bpiall_swi)
	163	sub sp, sp, #PT_REGS_SIZE
	164	stmia sp, {r0 - r12}
	165	mcr p15, 0, r8, c7, c5, 6 @ BPIALL
	166	isb
	167	b 3f
	168	ENDPROC(vector_bhb_bpiall_swi)
	169	#endif
	170	.align 5
	171	ENTRY(vector_swi)
	172	#ifdef CONFIG_CPU_V7M
	173	v7m_exception_entry
	174	#else
	175	sub sp, sp, #PT_REGS_SIZE
	176	stmia sp, {r0 - r12} @ Calling r0 - r12
	177	3:
	178	ARM( add r8, sp, #S_PC )
	179	ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
	180	THUMB( mov r8, sp )
	181	THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
	182	mrs saved_psr, spsr @ called from non-FIQ mode, so ok.
	183	TRACE( mov saved_pc, lr )
	184	str saved_pc, [sp, #S_PC] @ Save calling PC
	185	str saved_psr, [sp, #S_PSR] @ Save CPSR
	186	str r0, [sp, #S_OLD_R0] @ Save OLD_R0
	187	#endif
	188	reload_current r10, ip
	189	zero_fp
	190	alignment_trap r10, ip, cr_alignment
	191	asm_trace_hardirqs_on save=0
	192	enable_irq_notrace
	193	ct_user_exit save=0
	194
	195	/*
	196	* Get the system call number.
	197	*/
	198
	199	#if defined(CONFIG_OABI_COMPAT)
	200
	201	/*
	202	* If we have CONFIG_OABI_COMPAT then we need to look at the swi
	203	* value to determine if it is an EABI or an old ABI call.
	204	*/
	205	#ifdef CONFIG_ARM_THUMB
	206	tst saved_psr, #PSR_T_BIT
	207	movne r10, #0 @ no thumb OABI emulation
	208	USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction
	209	#else
	210	USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction
	211	#endif
	212	ARM_BE8(rev r10, r10) @ little endian instruction
	213
	214	#elif defined(CONFIG_AEABI)
	215
	216	/*
	217	* Pure EABI user space always put syscall number into scno (r7).
	218	*/
	219	#elif defined(CONFIG_ARM_THUMB)
	220	/* Legacy ABI only, possibly thumb mode. */
	221	tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs
	222	addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
	223	USER( ldreq scno, [saved_pc, #-4] )
	224
	225	#else
	226	/* Legacy ABI only. */
	227	USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction
	228	#endif
	229
	230	/* saved_psr and saved_pc are now dead */
	231
	232	uaccess_disable tbl
	233	get_thread_info tsk
	234
	235	adr tbl, sys_call_table @ load syscall table pointer
	236
	237	#if defined(CONFIG_OABI_COMPAT)
	238	/*
	239	* If the swi argument is zero, this is an EABI call and we do nothing.
	240	*
	241	* If this is an old ABI call, get the syscall number into scno and
	242	* get the old ABI syscall table address.
	243	*/
	244	bics r10, r10, #0xff000000
	245	strne r10, [tsk, #TI_ABI_SYSCALL]
	246	streq scno, [tsk, #TI_ABI_SYSCALL]
	247	eorne scno, r10, #__NR_OABI_SYSCALL_BASE
	248	ldrne tbl, =sys_oabi_call_table
	249	#elif !defined(CONFIG_AEABI)
	250	bic scno, scno, #0xff000000 @ mask off SWI op-code
	251	str scno, [tsk, #TI_ABI_SYSCALL]
	252	eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
	253	#else
	254	str scno, [tsk, #TI_ABI_SYSCALL]
	255	#endif
	256	/*
	257	* Reload the registers that may have been corrupted on entry to
	258	* the syscall assembly (by tracing or context tracking.)
	259	*/
	260	TRACE( ldmia sp, {r0 - r3} )
	261
	262	local_restart:
	263	ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
	264	stmdb sp!, {r4, r5} @ push fifth and sixth args
	265
	266	tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
	267	bne __sys_trace
	268
	269	invoke_syscall tbl, scno, r10, __ret_fast_syscall
	270
	271	add r1, sp, #S_OFF
	272	2: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
	273	eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
	274	bcs arm_syscall
	275	mov why, #0 @ no longer a real syscall
	276	b sys_ni_syscall @ not private func
	277
	278	#if defined(CONFIG_OABI_COMPAT) \|\| !defined(CONFIG_AEABI)
	279	/*
	280	* We failed to handle a fault trying to access the page
	281	* containing the swi instruction, but we're not really in a
	282	* position to return -EFAULT. Instead, return back to the
	283	* instruction and re-enter the user fault handling path trying
	284	* to page it in. This will likely result in sending SEGV to the
	285	* current task.
	286	*/
	287	9001:
	288	sub lr, saved_pc, #4
	289	str lr, [sp, #S_PC]
	290	get_thread_info tsk
	291	b ret_fast_syscall
	292	#endif
	293	ENDPROC(vector_swi)
	294	.ltorg
	295
	296	/*
	297	* This is the really slow path. We're going to be doing
	298	* context switches, and waiting for our parent to respond.
	299	*/
	300	__sys_trace:
	301	add r0, sp, #S_OFF
	302	bl syscall_trace_enter
	303	mov scno, r0
	304	invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
	305	cmp scno, #-1 @ skip the syscall?
	306	bne 2b
	307	add sp, sp, #S_OFF @ restore stack
	308
	309	__sys_trace_return_nosave:
	310	enable_irq_notrace
	311	mov r0, sp
	312	bl syscall_trace_exit
	313	b ret_slow_syscall
	314
	315	__sys_trace_return:
	316	str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
	317	mov r0, sp
	318	bl syscall_trace_exit
	319	b ret_slow_syscall
	320
	321	.macro syscall_table_start, sym
	322	.equ __sys_nr, 0
	323	.type \sym, #object
	324	ENTRY(\sym)
	325	.endm
	326
	327	.macro syscall, nr, func
	328	.ifgt __sys_nr - \nr
	329	.error "Duplicated/unorded system call entry"
	330	.endif
	331	.rept \nr - __sys_nr
	332	.long sys_ni_syscall
	333	.endr
	334	.long \func
	335	.equ __sys_nr, \nr + 1
	336	.endm
	337
	338	.macro syscall_table_end, sym
	339	.ifgt __sys_nr - __NR_syscalls
	340	.error "System call table too big"
	341	.endif
	342	.rept __NR_syscalls - __sys_nr
	343	.long sys_ni_syscall
	344	.endr
	345	.size \sym, . - \sym
	346	.endm
	347
	348	#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native)
	349	#define __SYSCALL(nr, func) syscall nr, func
	350
	351	/*
	352	* This is the syscall table declaration for native ABI syscalls.
	353	* With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
	354	*/
	355	syscall_table_start sys_call_table
	356	#ifdef CONFIG_AEABI
	357	#include <calls-eabi.S>
	358	#else
	359	#include <calls-oabi.S>
	360	#endif
	361	syscall_table_end sys_call_table
	362
	363	/*============================================================================
	364	* Special system call wrappers
	365	*/
	366	@ r0 = syscall number
	367	@ r8 = syscall table
	368	sys_syscall:
	369	bic scno, r0, #__NR_OABI_SYSCALL_BASE
	370	cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
	371	cmpne scno, #NR_syscalls @ check range
	372	#ifdef CONFIG_CPU_SPECTRE
	373	movhs scno, #0
	374	csdb
	375	#endif
	376	stmialo sp, {r5, r6} @ shuffle args
	377	movlo r0, r1
	378	movlo r1, r2
	379	movlo r2, r3
	380	movlo r3, r4
	381	ldrlo pc, [tbl, scno, lsl #2]
	382	b sys_ni_syscall
	383	ENDPROC(sys_syscall)
	384
	385	sys_sigreturn_wrapper:
	386	add r0, sp, #S_OFF
	387	mov why, #0 @ prevent syscall restart handling
	388	b sys_sigreturn
	389	ENDPROC(sys_sigreturn_wrapper)
	390
	391	sys_rt_sigreturn_wrapper:
	392	add r0, sp, #S_OFF
	393	mov why, #0 @ prevent syscall restart handling
	394	b sys_rt_sigreturn
	395	ENDPROC(sys_rt_sigreturn_wrapper)
	396
	397	sys_statfs64_wrapper:
	398	teq r1, #88
	399	moveq r1, #84
	400	b sys_statfs64
	401	ENDPROC(sys_statfs64_wrapper)
	402
	403	sys_fstatfs64_wrapper:
	404	teq r1, #88
	405	moveq r1, #84
	406	b sys_fstatfs64
	407	ENDPROC(sys_fstatfs64_wrapper)
	408
	409	/*
	410	* Note: off_4k (r5) is always units of 4K. If we can't do the requested
	411	* offset, we return EINVAL.
	412	*/
	413	sys_mmap2:
	414	str r5, [sp, #4]
	415	b sys_mmap_pgoff
	416	ENDPROC(sys_mmap2)
	417
	418	#ifdef CONFIG_OABI_COMPAT
	419
	420	/*
	421	* These are syscalls with argument register differences
	422	*/
	423
	424	sys_oabi_pread64:
	425	stmia sp, {r3, r4}
	426	b sys_pread64
	427	ENDPROC(sys_oabi_pread64)
	428
	429	sys_oabi_pwrite64:
	430	stmia sp, {r3, r4}
	431	b sys_pwrite64
	432	ENDPROC(sys_oabi_pwrite64)
	433
	434	sys_oabi_truncate64:
	435	mov r3, r2
	436	mov r2, r1
	437	b sys_truncate64
	438	ENDPROC(sys_oabi_truncate64)
	439
	440	sys_oabi_ftruncate64:
	441	mov r3, r2
	442	mov r2, r1
	443	b sys_ftruncate64
	444	ENDPROC(sys_oabi_ftruncate64)
	445
	446	sys_oabi_readahead:
	447	str r3, [sp]
	448	mov r3, r2
	449	mov r2, r1
	450	b sys_readahead
	451	ENDPROC(sys_oabi_readahead)
	452
	453	/*
	454	* Let's declare a second syscall table for old ABI binaries
	455	* using the compatibility syscall entries.
	456	*/
	457	syscall_table_start sys_oabi_call_table
	458	#undef __SYSCALL_WITH_COMPAT
	459	#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat)
	460	#include <calls-oabi.S>
	461	syscall_table_end sys_oabi_call_table
	462
	463	#endif
	464