/*
* Copyright (c) 2006-2020, RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2018-12-10 Jesven first version
* 2021-02-03 lizhirui port to riscv64
* 2021-02-19 lizhirui port to new version of rt-smart
* 2022-11-08 Wangxiaoyao Cleanup codes;
* Support new context switch
* 2023-07-16 Shell Move part of the codes to C from asm in signal handling
*/
#include "rtconfig.h"
#ifndef __ASSEMBLY__
#define __ASSEMBLY__
#endif /* __ASSEMBLY__ */
#include "cpuport.h"
#include "encoding.h"
#include "stackframe.h"
#include "asm-generic.h"
.section .text.lwp
/*
* void arch_start_umode(args, text, ustack, kstack);
*/
.global arch_start_umode
.type arch_start_umode, % function
arch_start_umode:
// load kstack for user process
csrw sscratch, a3
li t0, SSTATUS_SPP | SSTATUS_SIE // set as user mode, close interrupt
csrc sstatus, t0
li t0, SSTATUS_SPIE // enable interrupt when return to user mode
csrs sstatus, t0
csrw sepc, a1
mv sp, a2
sret//enter user mode
/*
* void arch_crt_start_umode(args, text, ustack, kstack);
*/
.global arch_crt_start_umode
.type arch_crt_start_umode, % function
arch_crt_start_umode:
li t0, SSTATUS_SPP | SSTATUS_SIE // set as user mode, close interrupt
csrc sstatus, t0
li t0, SSTATUS_SPIE // enable interrupt when return to user mode
csrs sstatus, t0
csrw sepc, a1
mv s0, a0
mv s1, a1
mv s2, a2
mv s3, a3
mv a0, s2
call lwp_copy_return_code_to_user_stack
mv a0, s2
call lwp_fix_sp
mv sp, a0//user_sp
mv ra, a0//return address
mv a0, s0//args
csrw sscratch, s3
sret//enter user mode
/**
* Unify exit point from kernel mode to enter user space
* we handle following things here:
* 1. restoring user mode debug state (not support yet)
* 2. handling thread's exit request
* 3. handling POSIX signal
* 4. restoring user context
* 5. jump to user mode
*/
.global arch_ret_to_user
arch_ret_to_user:
// TODO: we don't support kernel gdb server in risc-v yet
// so we don't check debug state here and handle debugging bussiness
call lwp_check_exit_request
beqz a0, 1f
mv a0, x0
call sys_exit
1:
mv a0, sp
call lwp_thread_signal_catch
ret_to_user_exit:
RESTORE_ALL
// `RESTORE_ALL` also reset sp to user sp, and setup sscratch
sret
/**
* Restore user context from exception frame stroraged in ustack
* And handle pending signals;
*/
arch_signal_quit:
LOAD a0, FRAME_OFF_SP(sp)
call arch_signal_ucontext_restore
/* reset kernel sp to the stack */
addi sp, sp, CTX_REG_NR * REGBYTES
STORE sp, FRAME_OFF_SP(a0)
/* return value is user sp */
mv sp, a0
/* restore user sp before enter trap */
addi a0, sp, CTX_REG_NR * REGBYTES
csrw sscratch, a0
RESTORE_ALL
SAVE_ALL
j arch_ret_to_user
/**
* rt_noreturn
* void arch_thread_signal_enter(
* int signo, -> a0
* siginfo_t *psiginfo, -> a1
* void *exp_frame, -> a2
* void *entry_uaddr, -> a3
* lwp_sigset_t *save_sig_mask, -> a4
* )
*/
.global arch_thread_signal_enter
arch_thread_signal_enter:
mv s3, a2
mv s2, a0
mv s1, a3
LOAD t0, FRAME_OFF_SP(a2)
mv a3, t0
call arch_signal_ucontext_save
/** restore kernel sp */
addi sp, s3, CTX_REG_NR * REGBYTES
/**
* set regiter RA to user signal handler
* set sp to user sp & save kernel sp in sscratch
*/
mv ra, a0
csrw sscratch, sp
mv sp, a0
/**
* s1 is signal_handler,
* s1 = !s1 ? lwp_sigreturn : s1;
*/
bnez s1, 1f
mv s1, ra
1:
/* enter user mode and enable interrupt when return to user mode */
li t0, SSTATUS_SPP
csrc sstatus, t0
li t0, SSTATUS_SPIE
csrs sstatus, t0
/* sepc <- signal_handler */
csrw sepc, s1
/* a0 <- signal id */
mv a0, s2
/* a1 <- siginfo */
add a1, sp, 16
/* dummy a2 */
mv a2, a1
/* restore user GP */
LOAD gp, FRAME_OFF_GP(s3)
/**
* handler(signo, psi, ucontext);
*/
sret
.align 3
lwp_debugreturn:
li a7, 0xff
ecall
.align 3
.global lwp_sigreturn
lwp_sigreturn:
li a7, 0xfe
ecall
.align 3
lwp_sigreturn_end:
.align 3
.global lwp_thread_return
lwp_thread_return:
li a0, 0
li a7, 1
ecall
.align 3
.global lwp_thread_return_end
lwp_thread_return_end:
.globl arch_get_tidr
arch_get_tidr:
mv a0, tp
ret
.global arch_set_thread_area
arch_set_thread_area:
.globl arch_set_tidr
arch_set_tidr:
mv tp, a0
ret
.global arch_clone_exit
.global arch_fork_exit
arch_fork_exit:
arch_clone_exit:
j arch_syscall_exit
START_POINT(syscall_entry)
#ifndef ARCH_USING_NEW_CTX_SWITCH
//swap to thread kernel stack
csrr t0, sstatus
andi t0, t0, 0x100
beqz t0, __restore_sp_from_tcb
__restore_sp_from_sscratch: // from kernel
csrr t0, sscratch
j __move_stack_context
__restore_sp_from_tcb: // from user
jal rt_thread_self
jal get_thread_kernel_stack_top
mv t0, a0
__move_stack_context:
mv t1, sp//src
mv sp, t0//switch stack
addi sp, sp, -CTX_REG_NR * REGBYTES
//copy context
li s0, CTX_REG_NR//cnt
mv t2, sp//dst
copy_context_loop:
LOAD t0, 0(t1)
STORE t0, 0(t2)
addi s0, s0, -1
addi t1, t1, 8
addi t2, t2, 8
bnez s0, copy_context_loop
#endif /* ARCH_USING_NEW_CTX_SWITCH */
/* fetch SYSCALL ID */
LOAD a7, 17 * REGBYTES(sp)
addi a7, a7, -0xfe
beqz a7, arch_signal_quit
#ifdef ARCH_MM_MMU
/* save setting when syscall enter */
call rt_thread_self
call lwp_user_setting_save
#endif
mv a0, sp
OPEN_INTERRUPT
call syscall_handler
j arch_syscall_exit
START_POINT_END(syscall_entry)
.global arch_syscall_exit
arch_syscall_exit:
CLOSE_INTERRUPT
#if defined(ARCH_MM_MMU)
LOAD s0, FRAME_OFF_SSTATUS(sp)
andi s0, s0, 0x100
bnez s0, dont_ret_to_user
j arch_ret_to_user
#endif
dont_ret_to_user:
#ifdef ARCH_MM_MMU
/* restore setting when syscall exit */
call rt_thread_self
call lwp_user_setting_restore
/* after restore the reg `tp`, need modify context */
STORE tp, 4 * REGBYTES(sp)
#endif
//restore context
RESTORE_ALL
csrw sscratch, zero
sret