1 files changed, 461 insertions, 0 deletions
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
new file mode 100644
index 0000000000..5c31e9de7a
--- /dev/null
+++ b/arch/arm/kernel/entry-common.S
@@ -0,0 +1,461 @@
+/* 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
+
+	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
+