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ex-scall.S
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// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2005-2017 Andes Technology Corporation
#include <linux/linkage.h>
#include <asm/unistd.h>
#include <asm/assembler.h>
#include <asm/nds32.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/current.h>
/*
* $r0 = previous task_struct,
* $r1 = next task_struct,
* previous and next are guaranteed not to be the same.
*/
ENTRY(__switch_to)
la $p0, __entry_task
sw $r1, [$p0]
move $p1, $r0
addi $p1, $p1, #THREAD_CPU_CONTEXT
smw.bi $r6, [$p1], $r14, #0xb ! push r6~r14, fp, lp, sp
move $r25, $r1
addi $r1, $r1, #THREAD_CPU_CONTEXT
lmw.bi $r6, [$r1], $r14, #0xb ! pop r6~r14, fp, lp, sp
ret
#define tbl $r8
/*
* $r7 will be writen as syscall nr
*/
.macro get_scno
lwi $r7, [$sp + R15_OFFSET]
swi $r7, [$sp + SYSCALLNO_OFFSET]
.endm
.macro updateipc
addi $r17, $r13, #4 ! $r13 is $IPC
swi $r17, [$sp + IPC_OFFSET]
.endm
ENTRY(eh_syscall)
updateipc
get_scno
gie_enable
lwi $p0, [tsk+#TSK_TI_FLAGS] ! check for syscall tracing
andi $p1, $p0, #_TIF_WORK_SYSCALL_ENTRY ! are we tracing syscalls?
bnez $p1, __sys_trace
la $lp, ret_fast_syscall ! return address
jmp_systbl:
addi $p1, $r7, #-__NR_syscalls ! syscall number of syscall instruction is guarded by addembler
bgez $p1, _SCNO_EXCEED ! call sys_* routine
la tbl, sys_call_table ! load syscall table pointer
slli $p1, $r7, #2
add $p1, tbl, $p1
lwi $p1, [$p1]
jr $p1 ! no return
_SCNO_EXCEED:
ori $r0, $r7, #0
ori $r1, $sp, #0
b bad_syscall
/*
* This is the really slow path. We're going to be doing
* context switches, and waiting for our parent to respond.
*/
__sys_trace:
move $r0, $sp
bal syscall_trace_enter
move $r7, $r0
la $lp, __sys_trace_return ! return address
addi $p1, $r7, #1
beqz $p1, ret_slow_syscall ! fatal signal is pending
addi $p1, $sp, #R0_OFFSET ! pointer to regs
lmw.bi $r0, [$p1], $r5 ! have to reload $r0 - $r5
b jmp_systbl
__sys_trace_return:
swi $r0, [$sp+#R0_OFFSET] ! T: save returned $r0
move $r0, $sp ! set pt_regs for syscall_trace_leave
bal syscall_trace_leave
b ret_slow_syscall
ENTRY(sys_rt_sigreturn_wrapper)
addi $r0, $sp, #0
b sys_rt_sigreturn
ENDPROC(sys_rt_sigreturn_wrapper)