/* 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#elsesaved_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_nosaveslow_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 goENDPROC(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 interruptsENTRY(ret_to_user_from_irq)	ldr	r1, [tsk, #TI_FLAGS]	movs	r1, r1, lsl #16	bne	slow_work_pendingno_work_pending:	asm_trace_hardirqs_on save = 0 	ct_user_enter save = 0 #ifdef CONFIG_KSTACK_ERASE	bl	stackleak_erase_on_task_stack#endif	restore_user_regs fast = 0, offset = 0ENDPROC(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	r51:	get_thread_info tsk	b	ret_slow_syscallENDPROC(ret_from_fork) /*============================================================================= * SWI handler *----------------------------------------------------------------------------- */ 	.align	5#ifdef CONFIG_HARDEN_BRANCH_HISTORYENTRY(vector_bhb_loop8_swi)	sub	sp, sp, #PT_REGS_SIZE	stmia	sp, {r0 - r12}	mov	r8, #81:	b	2f2:	subs	r8, r8, #1	bne	1b	dsb	nsh	isb	b	3fENDPROC(vector_bhb_loop8_swi) 	.align	5ENTRY(vector_bhb_bpiall_swi)	sub	sp, sp, #PT_REGS_SIZE	stmia	sp, {r0 - r12}	mcr	p15, 0, r8, c7, c5, 6	@ BPIALL	isb	b	3fENDPROC(vector_bhb_bpiall_swi)#endif	.align	5ENTRY(vector_swi)#ifdef CONFIG_CPU_V7M	v7m_exception_entry#else	sub	sp, sp, #PT_REGS_SIZE	stmia	sp, {r0 - r12}			@ Calling r0 - r123: 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_OFF2:	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#endifENDPROC(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, #objectENTRY(\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 tablesys_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_syscallENDPROC(sys_syscall) sys_sigreturn_wrapper:		add	r0, sp, #S_OFF		mov	why, #0		@ prevent syscall restart handling		b	sys_sigreturnENDPROC(sys_sigreturn_wrapper) sys_rt_sigreturn_wrapper:		add	r0, sp, #S_OFF		mov	why, #0		@ prevent syscall restart handling		b	sys_rt_sigreturnENDPROC(sys_rt_sigreturn_wrapper) sys_statfs64_wrapper:		teq	r1, #88		moveq	r1, #84		b	sys_statfs64ENDPROC(sys_statfs64_wrapper) sys_fstatfs64_wrapper:		teq	r1, #88		moveq	r1, #84		b	sys_fstatfs64ENDPROC(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_pgoffENDPROC(sys_mmap2) #ifdef CONFIG_OABI_COMPAT /* * These are syscalls with argument register differences */ sys_oabi_pread64:		stmia	sp, {r3, r4}		b	sys_pread64ENDPROC(sys_oabi_pread64) sys_oabi_pwrite64:		stmia	sp, {r3, r4}		b	sys_pwrite64ENDPROC(sys_oabi_pwrite64) sys_oabi_truncate64:		mov	r3, r2		mov	r2, r1		b	sys_truncate64ENDPROC(sys_oabi_truncate64) sys_oabi_ftruncate64:		mov	r3, r2		mov	r2, r1		b	sys_ftruncate64ENDPROC(sys_oabi_ftruncate64) sys_oabi_readahead:		str	r3, [sp]		mov	r3, r2		mov	r2, r1		b	sys_readaheadENDPROC(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