/* *  linux/arch/arm/kernel/entry-common.S * *  Copyright (C) 2000 Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <asm/unistd.h>#include <asm/ftrace.h>#include <asm/unwind.h> #ifdef CONFIG_NEED_RET_TO_USER#include <mach/entry-macro.S>#else	.macro  arch_ret_to_user, tmp1, tmp2	.endm#endif #include "entry-header.S"  	.align	5/* * This is the fast syscall return path.  We do as little as * possible here, and this includes saving r0 back into the SVC * stack. */ret_fast_syscall: UNWIND(.fnstart	) UNWIND(.cantunwind	)	disable_irq				@ disable interrupts	ldr	r1, [tsk, #TI_FLAGS]	tst	r1, #_TIF_WORK_MASK	bne	fast_work_pending	asm_trace_hardirqs_on 	/* perform architecture specific actions before user return */	arch_ret_to_user r1, lr	ct_user_enter 	restore_user_regs fast = 1, offset = S_OFF UNWIND(.fnend		) /* * Ok, we need to do extra processing, enter the slow path. */fast_work_pending:	str	r0, [sp, #S_R0+S_OFF]!		@ returned r0work_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)	ldmia	sp, {r0 - r6}			@ have to reload r0 - r6	b	local_restart			@ ... and off we go /* * "slow" syscall return path.  "why" tells us if this was a real syscall. */ENTRY(ret_to_user)ret_slow_syscall:	disable_irq				@ disable interruptsENTRY(ret_to_user_from_irq)	ldr	r1, [tsk, #TI_FLAGS]	tst	r1, #_TIF_WORK_MASK	bne	work_pendingno_work_pending:	asm_trace_hardirqs_on 	/* perform architecture specific actions before user return */	arch_ret_to_user r1, lr	ct_user_enter save = 0 	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	adrne	lr, BSYM(1f)	movne	pc, r51:	get_thread_info tsk	b	ret_slow_syscallENDPROC(ret_from_fork) 	.equ NR_syscalls,0#define CALL(x) .equ NR_syscalls,NR_syscalls+1#include "calls.S" /* * Ensure that the system call table is equal to __NR_syscalls, * which is the value the rest of the system sees */.ifne NR_syscalls - __NR_syscalls.error "__NR_syscalls is not equal to the size of the syscall table".endif #undef CALL#define CALL(x) .long x #ifdef CONFIG_FUNCTION_TRACER/* * When compiling with -pg, gcc inserts a call to the mcount routine at the * start of every function.  In mcount, apart from the function's address (in * lr), we need to get hold of the function's caller's address. * * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this: * *	bl	mcount * * These versions have the limitation that in order for the mcount routine to * be able to determine the function's caller's address, an APCS-style frame * pointer (which is set up with something like the code below) is required. * *	mov     ip, sp *	push    {fp, ip, lr, pc} *	sub     fp, ip, #4 * * With EABI, these frame pointers are not available unless -mapcs-frame is * specified, and if building as Thumb-2, not even then. * * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount, * with call sites like: * *	push	{lr} *	bl	__gnu_mcount_nc * * With these compilers, frame pointers are not necessary. * * mcount can be thought of as a function called in the middle of a subroutine * call.  As such, it needs to be transparent for both the caller and the * callee: the original lr needs to be restored when leaving mcount, and no * registers should be clobbered.  (In the __gnu_mcount_nc implementation, we * clobber the ip register.  This is OK because the ARM calling convention * allows it to be clobbered in subroutines and doesn't use it to hold * parameters.) * * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0" * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see * arch/arm/kernel/ftrace.c). */ #ifndef CONFIG_OLD_MCOUNT#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.#endif#endif .macro mcount_adjust_addr rd, rn	bic	\rd, \rn, #1		@ clear the Thumb bit if present	sub	\rd, \rd, #MCOUNT_INSN_SIZE.endm .macro __mcount suffix	mcount_enter	ldr	r0, =ftrace_trace_function	ldr	r2, [r0]	adr	r0, .Lftrace_stub	cmp	r0, r2	bne	1f #ifdef CONFIG_FUNCTION_GRAPH_TRACER	ldr     r1, =ftrace_graph_return	ldr     r2, [r1]	cmp     r0, r2	bne     ftrace_graph_caller\suffix 	ldr     r1, =ftrace_graph_entry	ldr     r2, [r1]	ldr     r0, =ftrace_graph_entry_stub	cmp     r0, r2	bne     ftrace_graph_caller\suffix#endif 	mcount_exit 1: 	mcount_get_lr	r1			@ lr of instrumented func	mcount_adjust_addr	r0, lr		@ instrumented function	adr	lr, BSYM(2f)	mov	pc, r22:	mcount_exit.endm .macro __ftrace_caller suffix	mcount_enter 	mcount_get_lr	r1			@ lr of instrumented func	mcount_adjust_addr	r0, lr		@ instrumented function 	.globl ftrace_call\suffixftrace_call\suffix:	bl	ftrace_stub #ifdef CONFIG_FUNCTION_GRAPH_TRACER	.globl ftrace_graph_call\suffixftrace_graph_call\suffix:	mov	r0, r0#endif 	mcount_exit.endm .macro __ftrace_graph_caller	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)#ifdef CONFIG_DYNAMIC_FTRACE	@ called from __ftrace_caller, saved in mcount_enter	ldr	r1, [sp, #16]		@ instrumented routine (func)	mcount_adjust_addr	r1, r1#else	@ called from __mcount, untouched in lr	mcount_adjust_addr	r1, lr	@ instrumented routine (func)#endif	mov	r2, fp			@ frame pointer	bl	prepare_ftrace_return	mcount_exit.endm #ifdef CONFIG_OLD_MCOUNT/* * mcount */ .macro mcount_enter	stmdb	sp!, {r0-r3, lr}.endm .macro mcount_get_lr reg	ldr	\reg, [fp, #-4].endm .macro mcount_exit	ldr	lr, [fp, #-4]	ldmia	sp!, {r0-r3, pc}.endm ENTRY(mcount)#ifdef CONFIG_DYNAMIC_FTRACE	stmdb	sp!, {lr}	ldr	lr, [fp, #-4]	ldmia	sp!, {pc}#else	__mcount _old#endifENDPROC(mcount) #ifdef CONFIG_DYNAMIC_FTRACEENTRY(ftrace_caller_old)	__ftrace_caller _oldENDPROC(ftrace_caller_old)#endif #ifdef CONFIG_FUNCTION_GRAPH_TRACERENTRY(ftrace_graph_caller_old)	__ftrace_graph_callerENDPROC(ftrace_graph_caller_old)#endif .purgem mcount_enter.purgem mcount_get_lr.purgem mcount_exit#endif /* * __gnu_mcount_nc */ .macro mcount_enter/* * This pad compensates for the push {lr} at the call site.  Note that we are * unable to unwind through a function which does not otherwise save its lr. */ UNWIND(.pad	#4)	stmdb	sp!, {r0-r3, lr} UNWIND(.save	{r0-r3, lr}).endm .macro mcount_get_lr reg	ldr	\reg, [sp, #20].endm .macro mcount_exit	ldmia	sp!, {r0-r3, ip, lr}	mov	pc, ip.endm ENTRY(__gnu_mcount_nc)UNWIND(.fnstart)#ifdef CONFIG_DYNAMIC_FTRACE	mov	ip, lr	ldmia	sp!, {lr}	mov	pc, ip#else	__mcount#endifUNWIND(.fnend)ENDPROC(__gnu_mcount_nc) #ifdef CONFIG_DYNAMIC_FTRACEENTRY(ftrace_caller)UNWIND(.fnstart)	__ftrace_callerUNWIND(.fnend)ENDPROC(ftrace_caller)#endif #ifdef CONFIG_FUNCTION_GRAPH_TRACERENTRY(ftrace_graph_caller)UNWIND(.fnstart)	__ftrace_graph_callerUNWIND(.fnend)ENDPROC(ftrace_graph_caller)#endif .purgem mcount_enter.purgem mcount_get_lr.purgem mcount_exit #ifdef CONFIG_FUNCTION_GRAPH_TRACER	.globl return_to_handlerreturn_to_handler:	stmdb	sp!, {r0-r3}	mov	r0, fp			@ frame pointer	bl	ftrace_return_to_handler	mov	lr, r0			@ r0 has real ret addr	ldmia	sp!, {r0-r3}	mov	pc, lr#endif ENTRY(ftrace_stub).Lftrace_stub:	mov	pc, lrENDPROC(ftrace_stub) #endif /* CONFIG_FUNCTION_TRACER */ /*============================================================================= * SWI handler *----------------------------------------------------------------------------- */ 	.align	5ENTRY(vector_swi)#ifdef CONFIG_CPU_V7M	v7m_exception_entry#else	sub	sp, sp, #S_FRAME_SIZE	stmia	sp, {r0 - r12}			@ Calling r0 - r12 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	r8, spsr			@ called from non-FIQ mode, so ok.	str	lr, [sp, #S_PC]			@ Save calling PC	str	r8, [sp, #S_PSR]		@ Save CPSR	str	r0, [sp, #S_OLD_R0]		@ Save OLD_R0#endif	zero_fp #ifdef CONFIG_ALIGNMENT_TRAP	ldr	ip, __cr_alignment	ldr	ip, [ip]	mcr	p15, 0, ip, c1, c0		@ update control register#endif 	enable_irq	ct_user_exit	get_thread_info tsk 	/*	 * 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	r8, #PSR_T_BIT	movne	r10, #0				@ no thumb OABI emulation USER(	ldreq	r10, [lr, #-4]		)	@ get SWI instruction#else USER(	ldr	r10, [lr, #-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	r8, #PSR_T_BIT			@ this is SPSR from save_user_regs	addne	scno, r7, #__NR_SYSCALL_BASE	@ put OS number in USER(	ldreq	scno, [lr, #-4]		) #else	/* Legacy ABI only. */ USER(	ldr	scno, [lr, #-4]		)	@ get SWI instruction#endif 	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	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	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number#endif 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 	cmp	scno, #NR_syscalls		@ check upper syscall limit	adr	lr, BSYM(ret_fast_syscall)	@ return address	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine 	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, lr, #4	str	lr, [sp, #S_PC]	b	ret_fast_syscall#endifENDPROC(vector_swi) 	/*	 * This is the really slow path.  We're going to be doing	 * context switches, and waiting for our parent to respond.	 */__sys_trace:	mov	r1, scno	add	r0, sp, #S_OFF	bl	syscall_trace_enter 	adr	lr, BSYM(__sys_trace_return)	@ return address	mov	scno, r0			@ syscall number (possibly new)	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs	cmp	scno, #NR_syscalls		@ check upper syscall limit	ldmccia	r1, {r0 - r6}			@ have to reload r0 - r6	stmccia	sp, {r4, r5}			@ and update the stack args	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine	cmp	scno, #-1			@ skip the syscall?	bne	2b	add	sp, sp, #S_OFF			@ restore stack	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 	.align	5#ifdef CONFIG_ALIGNMENT_TRAP	.type	__cr_alignment, #object__cr_alignment:	.word	cr_alignment#endif	.ltorg /*

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