348 lines
7.3 KiB
ArmAsm
348 lines
7.3 KiB
ArmAsm
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/*
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* Copyright (c) 2006-2020, RT-Thread Development Team
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Change Logs:
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* Date Author Notes
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* 2018-12-10 Jesven first version
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* 2021-02-03 lizhirui port to riscv64
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* 2021-02-19 lizhirui port to new version of rt-smart
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* 2022-11-08 Wangxiaoyao Cleanup codes;
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* Support new context switch
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*/
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#include "rtconfig.h"
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#ifndef __ASSEMBLY__
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#define __ASSEMBLY__
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#endif /* __ASSEMBLY__ */
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#include "cpuport.h"
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#include "encoding.h"
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#include "stackframe.h"
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.section .text.lwp
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/*
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* void arch_start_umode(args, text, ustack, kstack);
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*/
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.global arch_start_umode
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.type arch_start_umode, % function
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arch_start_umode:
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// load kstack for user process
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csrw sscratch, a3
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li t0, SSTATUS_SPP | SSTATUS_SIE // set as user mode, close interrupt
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csrc sstatus, t0
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li t0, SSTATUS_SPIE // enable interrupt when return to user mode
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csrs sstatus, t0
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csrw sepc, a1
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mv a3, a2
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sret//enter user mode
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/*
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* void arch_crt_start_umode(args, text, ustack, kstack);
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*/
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.global arch_crt_start_umode
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.type arch_crt_start_umode, % function
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arch_crt_start_umode:
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li t0, SSTATUS_SPP | SSTATUS_SIE // set as user mode, close interrupt
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csrc sstatus, t0
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li t0, SSTATUS_SPIE // enable interrupt when return to user mode
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csrs sstatus, t0
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csrw sepc, a1
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mv s0, a0
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mv s1, a1
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mv s2, a2
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mv s3, a3
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mv a0, s2
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call lwp_copy_return_code_to_user_stack
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mv a0, s2
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call lwp_fix_sp
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mv sp, a0//user_sp
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mv ra, a0//return address
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mv a0, s0//args
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csrw sscratch, s3
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sret//enter user mode
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/**
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* Unify exit point from kernel mode to enter user space
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* we handle following things here:
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* 1. restoring user mode debug state (not support yet)
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* 2. handling thread's exit request
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* 3. handling POSIX signal
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* 4. restoring user context
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* 5. jump to user mode
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*/
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.global arch_ret_to_user
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arch_ret_to_user:
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// TODO: we don't support kernel gdb server in risc-v yet
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// so we don't check debug state here and handle debugging bussiness
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call lwp_check_exit_request
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beqz a0, 1f
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mv a0, x0
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call sys_exit
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1:
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call lwp_signal_check
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beqz a0, ret_to_user_exit
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J user_do_signal
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ret_to_user_exit:
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RESTORE_ALL
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// `RESTORE_ALL` also reset sp to user sp, and setup sscratch
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sret
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/**
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* Restore user context from exception frame stroraged in ustack
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* And handle pending signals;
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*/
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arch_signal_quit:
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call lwp_signal_restore
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call arch_get_usp_from_uctx
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// return value is user sp
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mv sp, a0
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// restore user sp before enter trap
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addi a0, sp, CTX_REG_NR * REGBYTES
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csrw sscratch, a0
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RESTORE_ALL
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SAVE_ALL
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j arch_ret_to_user
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/**
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* Prepare and enter user signal handler
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* Move user exception frame and setup signal return
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* routine in user stack
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*/
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user_do_signal:
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/* prefetch ustack to avoid corrupted status in RESTORE/STORE pair below */
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LOAD t0, FRAME_OFF_SP(sp)
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addi t1, t0, -CTX_REG_NR * REGBYTES
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LOAD t2, (t0)
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li t3, -0x1000
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1:
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add t0, t0, t3
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LOAD t2, (t0)
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bgt t0, t1, 1b
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/** restore and backup kernel sp carefully to avoid leaking */
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addi t0, sp, CTX_REG_NR * REGBYTES
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csrw sscratch, t0
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RESTORE_ALL
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SAVE_ALL
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/**
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* save lwp_sigreturn in user memory
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*/
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mv s0, sp
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la t0, lwp_sigreturn
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la t1, lwp_sigreturn_end
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// t1 <- size
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sub t1, t1, t0
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// s0 <- dst
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sub s0, s0, t1
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mv s2, t1
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lwp_sigreturn_copy_loop:
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addi t2, t1, -1
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add t3, t0, t2
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add t4, s0, t2
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lb t5, 0(t3)
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sb t5, 0(t4)
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mv t1, t2
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bnez t1, lwp_sigreturn_copy_loop
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/**
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* 1. clear sscratch & restore kernel sp to
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* enter kernel mode routine
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* 2. storage exp frame address to restore context,
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* by calling to lwp_signal_backup
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* 3. storage lwp_sigreturn entry address
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* 4. get signal id as param for signal handler
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*/
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mv s1, sp
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csrrw sp, sscratch, x0
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/**
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* synchronize dcache & icache if target is
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* a Harvard Architecture machine, otherwise
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* do nothing
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*/
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mv a0, s0
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mv a1, s2
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call rt_hw_sync_cache_local
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/**
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* backup user sp (point to saved exception frame, skip sigreturn routine)
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* And get signal id
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* a0: user sp
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* a1: user_pc (not used, marked as 0 to avoid abuse)
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* a2: user_flag (not used, marked as 0 to avoid abuse)
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*/
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mv a0, s1
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mv a1, zero
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mv a2, zero
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call lwp_signal_backup
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/**
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* backup signal id in s2,
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* and get sighandler by signal id
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*/
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mv s2, a0
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call lwp_sighandler_get
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/**
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* set regiter RA to user signal handler
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* set sp to user sp & save kernel sp in sscratch
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*/
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mv ra, s0
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csrw sscratch, sp
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mv sp, s0
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/**
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* a0 is signal_handler,
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* s1 = s0 == NULL ? lwp_sigreturn : s0;
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*/
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mv s1, s0
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beqz a0, skip_user_signal_handler
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mv s1, a0
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skip_user_signal_handler:
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// enter user mode and enable interrupt when return to user mode
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li t0, SSTATUS_SPP
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csrc sstatus, t0
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li t0, SSTATUS_SPIE
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csrs sstatus, t0
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// sepc <- signal_handler
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csrw sepc, s1
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// a0 <- signal id
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mv a0, s2
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sret
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.align 3
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lwp_debugreturn:
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li a7, 0xff
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ecall
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.align 3
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lwp_sigreturn:
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li a7, 0xfe
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ecall
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.align 3
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lwp_sigreturn_end:
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.align 3
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.global lwp_thread_return
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lwp_thread_return:
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li a0, 0
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li a7, 1
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ecall
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.align 3
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.global lwp_thread_return_end
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lwp_thread_return_end:
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.globl arch_get_tidr
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arch_get_tidr:
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mv a0, tp
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ret
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.global arch_set_thread_area
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arch_set_thread_area:
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.globl arch_set_tidr
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arch_set_tidr:
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mv tp, a0
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ret
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.global arch_clone_exit
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.global arch_fork_exit
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arch_fork_exit:
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arch_clone_exit:
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j arch_syscall_exit
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.global syscall_entry
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syscall_entry:
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#ifndef ARCH_USING_NEW_CTX_SWITCH
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//swap to thread kernel stack
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csrr t0, sstatus
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andi t0, t0, 0x100
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beqz t0, __restore_sp_from_tcb
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__restore_sp_from_sscratch: // from kernel
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csrr t0, sscratch
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j __move_stack_context
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__restore_sp_from_tcb: // from user
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la a0, rt_current_thread
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LOAD a0, 0(a0)
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jal get_thread_kernel_stack_top
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mv t0, a0
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__move_stack_context:
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mv t1, sp//src
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mv sp, t0//switch stack
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addi sp, sp, -CTX_REG_NR * REGBYTES
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//copy context
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li s0, CTX_REG_NR//cnt
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mv t2, sp//dst
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copy_context_loop:
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LOAD t0, 0(t1)
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STORE t0, 0(t2)
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addi s0, s0, -1
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addi t1, t1, 8
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addi t2, t2, 8
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bnez s0, copy_context_loop
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#endif /* ARCH_USING_NEW_CTX_SWITCH */
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/* fetch SYSCALL ID */
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LOAD a7, 17 * REGBYTES(sp)
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addi a7, a7, -0xfe
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beqz a7, arch_signal_quit
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#ifdef ARCH_MM_MMU
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/* save setting when syscall enter */
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call rt_thread_self
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call lwp_user_setting_save
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#endif
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mv a0, sp
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OPEN_INTERRUPT
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call syscall_handler
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j arch_syscall_exit
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.global arch_syscall_exit
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arch_syscall_exit:
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CLOSE_INTERRUPT
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#if defined(ARCH_MM_MMU)
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LOAD s0, 2 * REGBYTES(sp)
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andi s0, s0, 0x100
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bnez s0, dont_ret_to_user
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j arch_ret_to_user
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#endif
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dont_ret_to_user:
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#ifdef ARCH_MM_MMU
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/* restore setting when syscall exit */
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call rt_thread_self
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call lwp_user_setting_restore
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/* after restore the reg `tp`, need modify context */
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STORE tp, 4 * REGBYTES(sp)
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#endif
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//restore context
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RESTORE_ALL
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csrw sscratch, zero
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sret
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