/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* linux/arch/arm/kernel/entry-common.S
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*
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* Copyright (C) 2000 Russell King
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* Copyright (C) 2005 Stelian Pop.
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*/
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#include <asm/assembler.h>
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#include <asm/unistd.h>
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#include <asm/ftrace.h>
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#include <asm/unwind.h>
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#include <asm/memory.h>
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#ifdef CONFIG_AEABI
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#include <asm/unistd-oabi.h>
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#include <uapi/asm-generic/dovetail.h>
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#endif
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.equ NR_syscalls, __NR_syscalls
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#ifdef CONFIG_NEED_RET_TO_USER
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#include <mach/entry-macro.S>
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#else
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.macro arch_ret_to_user, tmp1, tmp2
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.endm
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#endif
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#include "entry-header.S"
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saved_psr .req r8
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#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING)
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saved_pc .req r9
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#define TRACE(x...) x
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#else
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saved_pc .req lr
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#define TRACE(x...)
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#endif
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.section .entry.text,"ax",%progbits
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.align 5
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#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \
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IS_ENABLED(CONFIG_DEBUG_RSEQ))
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/*
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* This is the fast syscall return path. We do as little as possible here,
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* such as avoiding writing r0 to the stack. We only use this path if we
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* have tracing, context tracking and rseq debug disabled - the overheads
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* from those features make this path too inefficient.
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*/
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ret_fast_syscall:
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__ret_fast_syscall:
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UNWIND(.fnstart )
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UNWIND(.cantunwind )
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disable_irq_notrace @ disable interrupts
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ldr r2, [tsk, #TI_ADDR_LIMIT]
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cmp r2, #TASK_SIZE
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blne addr_limit_check_failed
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ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
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movs r1, r1, lsl #16
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ldr r2, =#_TIF_SYSCALL_WORK | _TIF_WORK_MASK
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ands r2, r1, r2
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bne fast_work_pending
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/* perform architecture specific actions before user return */
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arch_ret_to_user r1, lr
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restore_user_regs fast = 1, offset = S_OFF
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UNWIND(.fnend )
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ENDPROC(ret_fast_syscall)
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/* Ok, we need to do extra processing, enter the slow path. */
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fast_work_pending:
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str r0, [sp, #S_R0+S_OFF]! @ returned r0
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/* fall through to work_pending */
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#else
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/*
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* The "replacement" ret_fast_syscall for when tracing, context tracking,
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* or rseq debug is enabled. As we will need to call out to some C functions,
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* we save r0 first to avoid needing to save registers around each C function
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* call.
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*/
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ret_fast_syscall:
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__ret_fast_syscall:
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UNWIND(.fnstart )
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UNWIND(.cantunwind )
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str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
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#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
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/* do_rseq_syscall needs interrupts enabled. */
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mov r0, sp @ 'regs'
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bl do_rseq_syscall
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#endif
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disable_irq_notrace @ disable interrupts
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ldr r2, [tsk, #TI_ADDR_LIMIT]
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cmp r2, #TASK_SIZE
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blne addr_limit_check_failed
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ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
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movs r1, r1, lsl #16
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ldr r2, =#_TIF_SYSCALL_WORK | _TIF_WORK_MASK
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ands r2, r1, r2
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beq no_work_pending
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UNWIND(.fnend )
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ENDPROC(ret_fast_syscall)
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/* Slower path - fall through to work_pending */
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#endif
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tst r1, #_TIF_SYSCALL_WORK
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bne __sys_trace_return_nosave
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slow_work_pending:
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mov r0, sp @ 'regs'
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mov r2, why @ 'syscall'
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bl do_work_pending
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cmp r0, #0
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beq no_work_pending
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movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
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ldmia sp, {r0 - r6} @ have to reload r0 - r6
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b local_restart @ ... and off we go
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ENDPROC(ret_fast_syscall)
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/*
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* "slow" syscall return path. "why" tells us if this was a real syscall.
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* IRQs may be enabled here, so always disable them. Note that we use the
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* "notrace" version to avoid calling into the tracing code unnecessarily.
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* do_work_pending() will update this state if necessary.
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*/
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ENTRY(ret_to_user)
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ret_slow_syscall:
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#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
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/* do_rseq_syscall needs interrupts enabled. */
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enable_irq_notrace @ enable interrupts
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mov r0, sp @ 'regs'
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bl do_rseq_syscall
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#endif
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disable_irq_notrace @ disable interrupts
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ENTRY(ret_to_user_from_irq)
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ldr r2, [tsk, #TI_ADDR_LIMIT]
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cmp r2, #TASK_SIZE
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blne addr_limit_check_failed
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ldr r1, [tsk, #TI_FLAGS]
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movs r1, r1, lsl #16
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ldr r2, =#_TIF_WORK_MASK
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ands r2, r1, r2
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bne slow_work_pending
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no_work_pending:
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asm_trace_hardirqs_on save = 0
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/* perform architecture specific actions before user return */
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arch_ret_to_user r1, lr
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ct_user_enter save = 0
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restore_user_regs fast = 0, offset = 0
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ENDPROC(ret_to_user_from_irq)
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ENDPROC(ret_to_user)
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ENTRY(fast_ret_to_user)
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disable_irq_notrace @ disable interrupts
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b no_work_pending
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ENDPROC(fast_ret_to_user)
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/*
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* This is how we return from a fork.
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*/
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ENTRY(ret_from_fork)
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bl schedule_tail
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cmp r5, #0
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movne r0, r4
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badrne lr, 1f
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retne r5
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1: get_thread_info tsk
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b ret_slow_syscall
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ENDPROC(ret_from_fork)
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/*=============================================================================
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* SWI handler
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*-----------------------------------------------------------------------------
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*/
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.align 5
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#ifdef CONFIG_HARDEN_BRANCH_HISTORY
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ENTRY(vector_bhb_loop8_swi)
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sub sp, sp, #PT_REGS_SIZE
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stmia sp, {r0 - r12}
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mov r8, #8
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1: b 2f
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2: subs r8, r8, #1
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bne 1b
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dsb
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isb
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b 3f
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ENDPROC(vector_bhb_loop8_swi)
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.align 5
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ENTRY(vector_bhb_bpiall_swi)
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sub sp, sp, #PT_REGS_SIZE
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stmia sp, {r0 - r12}
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mcr p15, 0, r8, c7, c5, 6 @ BPIALL
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isb
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b 3f
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ENDPROC(vector_bhb_bpiall_swi)
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#endif
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.align 5
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ENTRY(vector_swi)
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#ifdef CONFIG_CPU_V7M
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v7m_exception_entry
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#else
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sub sp, sp, #PT_REGS_SIZE
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stmia sp, {r0 - r12} @ Calling r0 - r12
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3:
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ARM( add r8, sp, #S_PC )
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ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
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THUMB( mov r8, sp )
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THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
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mrs saved_psr, spsr @ called from non-FIQ mode, so ok.
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TRACE( mov saved_pc, lr )
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str saved_pc, [sp, #S_PC] @ Save calling PC
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str saved_psr, [sp, #S_PSR] @ Save CPSR
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str r0, [sp, #S_OLD_R0] @ Save OLD_R0
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#endif
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zero_fp
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alignment_trap r10, ip, __cr_alignment
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asm_trace_hardirqs_on save=0
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enable_irq_notrace
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ct_user_exit save=0
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/*
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* Get the system call number.
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*/
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#if defined(CONFIG_OABI_COMPAT)
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/*
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* If we have CONFIG_OABI_COMPAT then we need to look at the swi
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* value to determine if it is an EABI or an old ABI call.
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*/
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#ifdef CONFIG_ARM_THUMB
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tst saved_psr, #PSR_T_BIT
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movne r10, #0 @ no thumb OABI emulation
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USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction
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#else
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USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction
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#endif
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ARM_BE8(rev r10, r10) @ little endian instruction
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#elif defined(CONFIG_AEABI)
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/*
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* Pure EABI user space always put syscall number into scno (r7).
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*/
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#elif defined(CONFIG_ARM_THUMB)
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/* Legacy ABI only, possibly thumb mode. */
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tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs
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addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
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USER( ldreq scno, [saved_pc, #-4] )
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#else
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/* Legacy ABI only. */
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USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction
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#endif
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/* saved_psr and saved_pc are now dead */
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uaccess_disable tbl
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adr tbl, sys_call_table @ load syscall table pointer
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#if defined(CONFIG_OABI_COMPAT)
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/*
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* If the swi argument is zero, this is an EABI call and we do nothing.
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*
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* If this is an old ABI call, get the syscall number into scno and
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* get the old ABI syscall table address.
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*/
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bics r10, r10, #0xff000000
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eorne scno, r10, #__NR_OABI_SYSCALL_BASE
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ldrne tbl, =sys_oabi_call_table
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#elif !defined(CONFIG_AEABI)
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bic scno, scno, #0xff000000 @ mask off SWI op-code
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eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
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#endif
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get_thread_info tsk
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#ifdef CONFIG_DOVETAIL
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str scno, [tsk, #TI_SYSCALL]
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#endif
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/*
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* Reload the registers that may have been corrupted on entry to
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* the syscall assembly (by tracing or context tracking.)
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*/
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TRACE( ldmia sp, {r0 - r3} )
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local_restart:
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#ifdef CONFIG_DOVETAIL
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ldr r10, [tsk, #TI_LOCAL_FLAGS] @ tsk(r10) is callee-saved
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#ifdef CONFIG_IPIPE_COMPAT
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ldr r0, =#0xf0042 @ old syscall signature
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cmp scno, r0
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bne 1f
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add scno, scno, #__OOB_SYSCALL_BIT @ force in oob marker
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b fastcall_try
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1:
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#endif
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#ifdef CONFIG_DOVETAIL_LEGACY_SYSCALL_RANGE
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ldr r0, =#__OOB_SYSCALL_BIT
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ands r0, scno, r0
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bne fastcall_try
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#endif
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cmp scno, #__NR_prctl
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bne slow_path
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ldr r0, [sp, #S_OLD_R0]
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tst r0, #__OOB_SYSCALL_BIT
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beq slow_path
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fastcall_try:
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tst r10, #_TLF_OOB
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beq slow_path
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mov r0, sp @ regs
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bl handle_oob_syscall
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ldr r10, [tsk, #TI_LOCAL_FLAGS]
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tst r0, r0
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beq slow_path
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tst r10, #_TLF_OOB
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bne fastcall_exit_check @ check for MAYDAY
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bl sync_inband_irqs
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b ret_slow_syscall
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fastcall_exit_check:
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ldr r10, [tsk, #TI_FLAGS]
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tst r10, #_TIF_MAYDAY
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beq fast_ret_to_user
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mov r0, sp
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bl dovetail_call_mayday
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b fast_ret_to_user
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slow_path:
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tst r10, #_TLF_DOVETAIL
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bne pipeline_syscall
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#ifdef CONFIG_DOVETAIL_LEGACY_SYSCALL_RANGE
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ldr r0, =#__OOB_SYSCALL_BIT
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ands r0, scno, r0
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bne pipeline_syscall
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#endif
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cmp scno, #__NR_prctl
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bne root_syscall
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ldr r0, [sp, #S_OLD_R0]
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tst r0, #__OOB_SYSCALL_BIT
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beq root_syscall
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pipeline_syscall:
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mov r0, sp @ regs
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bl __pipeline_syscall
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ldr r10, [tsk, #TI_LOCAL_FLAGS]
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tst r10, #_TLF_OOB
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bne fast_ret_to_user
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cmp r0, #0
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bgt ret_slow_syscall
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root_syscall:
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ldmia sp, { r0 - r3 }
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#endif /* CONFIG_DOVETAIL */
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ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
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stmdb sp!, {r4, r5} @ push fifth and sixth args
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tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
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bne __sys_trace
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invoke_syscall tbl, scno, r10, __ret_fast_syscall
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add r1, sp, #S_OFF
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2: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
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eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
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bcs arm_syscall
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mov why, #0 @ no longer a real syscall
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b sys_ni_syscall @ not private func
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#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
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/*
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* We failed to handle a fault trying to access the page
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* containing the swi instruction, but we're not really in a
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* position to return -EFAULT. Instead, return back to the
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* instruction and re-enter the user fault handling path trying
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* to page it in. This will likely result in sending SEGV to the
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* current task.
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*/
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9001:
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sub lr, saved_pc, #4
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str lr, [sp, #S_PC]
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get_thread_info tsk
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b ret_fast_syscall
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#endif
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ENDPROC(vector_swi)
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/*
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* This is the really slow path. We're going to be doing
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* context switches, and waiting for our parent to respond.
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*/
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__sys_trace:
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mov r1, scno
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add r0, sp, #S_OFF
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bl syscall_trace_enter
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mov scno, r0
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invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
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cmp scno, #-1 @ skip the syscall?
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bne 2b
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add sp, sp, #S_OFF @ restore stack
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__sys_trace_return_nosave:
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enable_irq_notrace
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mov r0, sp
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bl syscall_trace_exit
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b ret_slow_syscall
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__sys_trace_return:
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str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
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mov r0, sp
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bl syscall_trace_exit
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b ret_slow_syscall
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.align 5
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#ifdef CONFIG_ALIGNMENT_TRAP
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.type __cr_alignment, #object
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__cr_alignment:
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.word cr_alignment
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#endif
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.ltorg
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.macro syscall_table_start, sym
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.equ __sys_nr, 0
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.type \sym, #object
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ENTRY(\sym)
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.endm
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.macro syscall, nr, func
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.ifgt __sys_nr - \nr
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.error "Duplicated/unorded system call entry"
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.endif
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.rept \nr - __sys_nr
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.long sys_ni_syscall
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.endr
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.long \func
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.equ __sys_nr, \nr + 1
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.endm
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.macro syscall_table_end, sym
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.ifgt __sys_nr - __NR_syscalls
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.error "System call table too big"
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.endif
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.rept __NR_syscalls - __sys_nr
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.long sys_ni_syscall
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.endr
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.size \sym, . - \sym
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.endm
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#define NATIVE(nr, func) syscall nr, func
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/*
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* This is the syscall table declaration for native ABI syscalls.
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* With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
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*/
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syscall_table_start sys_call_table
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#define COMPAT(nr, native, compat) syscall nr, native
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#ifdef CONFIG_AEABI
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#include <calls-eabi.S>
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#else
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#include <calls-oabi.S>
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#endif
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#undef COMPAT
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syscall_table_end sys_call_table
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/*============================================================================
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* Special system call wrappers
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*/
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@ r0 = syscall number
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@ r8 = syscall table
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sys_syscall:
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bic scno, r0, #__NR_OABI_SYSCALL_BASE
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cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
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cmpne scno, #NR_syscalls @ check range
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#ifdef CONFIG_CPU_SPECTRE
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movhs scno, #0
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csdb
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#endif
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stmialo sp, {r5, r6} @ shuffle args
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movlo r0, r1
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movlo r1, r2
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movlo r2, r3
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movlo r3, r4
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ldrlo pc, [tbl, scno, lsl #2]
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b sys_ni_syscall
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ENDPROC(sys_syscall)
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sys_sigreturn_wrapper:
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add r0, sp, #S_OFF
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mov why, #0 @ prevent syscall restart handling
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b sys_sigreturn
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ENDPROC(sys_sigreturn_wrapper)
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sys_rt_sigreturn_wrapper:
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add r0, sp, #S_OFF
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mov why, #0 @ prevent syscall restart handling
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b sys_rt_sigreturn
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ENDPROC(sys_rt_sigreturn_wrapper)
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sys_statfs64_wrapper:
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teq r1, #88
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moveq r1, #84
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b sys_statfs64
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ENDPROC(sys_statfs64_wrapper)
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sys_fstatfs64_wrapper:
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teq r1, #88
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moveq r1, #84
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b sys_fstatfs64
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ENDPROC(sys_fstatfs64_wrapper)
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/*
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* Note: off_4k (r5) is always units of 4K. If we can't do the requested
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* offset, we return EINVAL.
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*/
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sys_mmap2:
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str r5, [sp, #4]
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b sys_mmap_pgoff
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ENDPROC(sys_mmap2)
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#ifdef CONFIG_OABI_COMPAT
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/*
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* These are syscalls with argument register differences
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*/
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sys_oabi_pread64:
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stmia sp, {r3, r4}
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b sys_pread64
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ENDPROC(sys_oabi_pread64)
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sys_oabi_pwrite64:
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stmia sp, {r3, r4}
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b sys_pwrite64
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ENDPROC(sys_oabi_pwrite64)
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sys_oabi_truncate64:
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mov r3, r2
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mov r2, r1
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b sys_truncate64
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ENDPROC(sys_oabi_truncate64)
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sys_oabi_ftruncate64:
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mov r3, r2
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mov r2, r1
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b sys_ftruncate64
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ENDPROC(sys_oabi_ftruncate64)
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sys_oabi_readahead:
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str r3, [sp]
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mov r3, r2
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mov r2, r1
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b sys_readahead
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ENDPROC(sys_oabi_readahead)
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/*
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* Let's declare a second syscall table for old ABI binaries
|
* using the compatibility syscall entries.
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*/
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syscall_table_start sys_oabi_call_table
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#define COMPAT(nr, native, compat) syscall nr, compat
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#include <calls-oabi.S>
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syscall_table_end sys_oabi_call_table
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#endif
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