| /* |
| * Copyright (c) 2016 Jean-Paul Etienne <fractalclone@gmail.com> |
| * Copyright (c) 2020 BayLibre, SAS |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| */ |
| |
| #include <kernel.h> |
| #include <ksched.h> |
| #include <arch/riscv/csr.h> |
| #include <stdio.h> |
| #include <core_pmp.h> |
| |
| #ifdef CONFIG_USERSPACE |
| |
| /* |
| * Glogal variable used to know the current mode running. |
| * Is not boolean because it must match the PMP granularity of the arch. |
| */ |
| ulong_t is_user_mode; |
| bool irq_flag; |
| #endif |
| |
| void z_thread_entry_wrapper(k_thread_entry_t thread, |
| void *arg1, |
| void *arg2, |
| void *arg3); |
| |
| void arch_new_thread(struct k_thread *thread, k_thread_stack_t *stack, |
| char *stack_ptr, k_thread_entry_t entry, |
| void *p1, void *p2, void *p3) |
| { |
| struct __esf *stack_init; |
| |
| #ifdef CONFIG_RISCV_SOC_CONTEXT_SAVE |
| const struct soc_esf soc_esf_init = {SOC_ESF_INIT}; |
| #endif |
| |
| /* Initial stack frame for thread */ |
| stack_init = (struct __esf *)Z_STACK_PTR_ALIGN( |
| Z_STACK_PTR_TO_FRAME(struct __esf, stack_ptr) |
| ); |
| |
| /* Setup the initial stack frame */ |
| stack_init->a0 = (ulong_t)entry; |
| stack_init->a1 = (ulong_t)p1; |
| stack_init->a2 = (ulong_t)p2; |
| stack_init->a3 = (ulong_t)p3; |
| |
| #ifdef CONFIG_THREAD_LOCAL_STORAGE |
| stack_init->tp = (ulong_t)thread->tls; |
| #endif |
| |
| /* |
| * Following the RISC-V architecture, |
| * the MSTATUS register (used to globally enable/disable interrupt), |
| * as well as the MEPC register (used to by the core to save the |
| * value of the program counter at which an interrupt/exception occcurs) |
| * need to be saved on the stack, upon an interrupt/exception |
| * and restored prior to returning from the interrupt/exception. |
| * This shall allow to handle nested interrupts. |
| * |
| * Given that context switching is performed via a system call exception |
| * within the RISCV architecture implementation, initially set: |
| * 1) MSTATUS to MSTATUS_DEF_RESTORE in the thread stack to enable |
| * interrupts when the newly created thread will be scheduled; |
| * 2) MEPC to the address of the z_thread_entry_wrapper in the thread |
| * stack. |
| * Hence, when going out of an interrupt/exception/context-switch, |
| * after scheduling the newly created thread: |
| * 1) interrupts will be enabled, as the MSTATUS register will be |
| * restored following the MSTATUS value set within the thread stack; |
| * 2) the core will jump to z_thread_entry_wrapper, as the program |
| * counter will be restored following the MEPC value set within the |
| * thread stack. |
| */ |
| stack_init->mstatus = MSTATUS_DEF_RESTORE; |
| |
| #if defined(CONFIG_PMP_STACK_GUARD) || defined(CONFIG_USERSPACE) |
| z_riscv_pmp_init_thread(thread); |
| #endif /* CONFIG_PMP_STACK_GUARD || CONFIG_USERSPACE */ |
| |
| #if defined(CONFIG_PMP_STACK_GUARD) |
| if ((thread->base.user_options & K_USER) == 0) { |
| /* Enable pmp for machine mode if thread isn't a user*/ |
| stack_init->mstatus |= MSTATUS_MPRV; |
| } |
| #endif /* CONFIG_PMP_STACK_GUARD */ |
| |
| #if defined(CONFIG_FPU) && defined(CONFIG_FPU_SHARING) |
| /* Shared FP mode: enable FPU of threads with K_FP_REGS. */ |
| if ((thread->base.user_options & K_FP_REGS) != 0) { |
| stack_init->mstatus |= MSTATUS_FS_INIT; |
| } |
| stack_init->fp_state = 0; |
| #elif defined(CONFIG_FPU) |
| /* Unshared FP mode: enable FPU of each thread. */ |
| stack_init->mstatus |= MSTATUS_FS_INIT; |
| #endif |
| |
| stack_init->mepc = (ulong_t)z_thread_entry_wrapper; |
| |
| #if defined(CONFIG_USERSPACE) |
| thread->arch.priv_stack_start = 0; |
| thread->arch.user_sp = 0; |
| if ((thread->base.user_options & K_USER) != 0) { |
| stack_init->mepc = (ulong_t)k_thread_user_mode_enter; |
| } else { |
| stack_init->mepc = (ulong_t)z_thread_entry_wrapper; |
| #if defined(CONFIG_PMP_STACK_GUARD) |
| z_riscv_init_stack_guard(thread); |
| #endif /* CONFIG_PMP_STACK_GUARD */ |
| } |
| #else |
| stack_init->mepc = (ulong_t)z_thread_entry_wrapper; |
| #if defined(CONFIG_PMP_STACK_GUARD) |
| z_riscv_init_stack_guard(thread); |
| #endif /* CONFIG_PMP_STACK_GUARD */ |
| #endif /* CONFIG_USERSPACE */ |
| |
| #ifdef CONFIG_RISCV_SOC_CONTEXT_SAVE |
| stack_init->soc_context = soc_esf_init; |
| #endif |
| |
| thread->callee_saved.sp = (ulong_t)stack_init; |
| } |
| |
| #if defined(CONFIG_FPU) && defined(CONFIG_FPU_SHARING) |
| int arch_float_disable(struct k_thread *thread) |
| { |
| unsigned int key; |
| |
| if (thread != _current) { |
| return -EINVAL; |
| } |
| |
| if (arch_is_in_isr()) { |
| return -EINVAL; |
| } |
| |
| /* Ensure a preemptive context switch does not occur */ |
| key = irq_lock(); |
| |
| /* Disable all floating point capabilities for the thread */ |
| thread->base.user_options &= ~K_FP_REGS; |
| |
| /* Clear the FS bits to disable the FPU. */ |
| __asm__ volatile ( |
| "mv t0, %0\n" |
| "csrrc x0, mstatus, t0\n" |
| : |
| : "r" (MSTATUS_FS_MASK) |
| ); |
| |
| irq_unlock(key); |
| |
| return 0; |
| } |
| |
| |
| int arch_float_enable(struct k_thread *thread, unsigned int options) |
| { |
| unsigned int key; |
| |
| if (thread != _current) { |
| return -EINVAL; |
| } |
| |
| if (arch_is_in_isr()) { |
| return -EINVAL; |
| } |
| |
| /* Ensure a preemptive context switch does not occur */ |
| key = irq_lock(); |
| |
| /* Enable all floating point capabilities for the thread. */ |
| thread->base.user_options |= K_FP_REGS; |
| |
| /* Set the FS bits to Initial to enable the FPU. */ |
| __asm__ volatile ( |
| "mv t0, %0\n" |
| "csrrs x0, mstatus, t0\n" |
| : |
| : "r" (MSTATUS_FS_INIT) |
| ); |
| |
| irq_unlock(key); |
| |
| return 0; |
| } |
| #endif /* CONFIG_FPU && CONFIG_FPU_SHARING */ |
| |
| #ifdef CONFIG_USERSPACE |
| |
| /* Function used by Zephyr to switch a supervisor thread to a user thread */ |
| FUNC_NORETURN void arch_user_mode_enter(k_thread_entry_t user_entry, |
| void *p1, void *p2, void *p3) |
| { |
| arch_syscall_invoke5((uintptr_t) arch_user_mode_enter, |
| (uintptr_t) user_entry, |
| (uintptr_t) p1, |
| (uintptr_t) p2, |
| (uintptr_t) p3, |
| FORCE_SYSCALL_ID); |
| |
| CODE_UNREACHABLE; |
| } |
| |
| /* |
| * User space entry function |
| * |
| * This function is the entry point to user mode from privileged execution. |
| * The conversion is one way, and threads which transition to user mode do |
| * not transition back later, unless they are doing system calls. |
| */ |
| FUNC_NORETURN void z_riscv_user_mode_enter_syscall(k_thread_entry_t user_entry, |
| void *p1, void *p2, void *p3) |
| { |
| ulong_t top_of_user_stack = 0U; |
| uintptr_t status; |
| |
| /* Set up privileged stack */ |
| #ifdef CONFIG_GEN_PRIV_STACKS |
| _current->arch.priv_stack_start = |
| (uint32_t)z_priv_stack_find(_current->stack_obj); |
| #else |
| _current->arch.priv_stack_start = |
| (uint32_t)(_current->stack_obj) + |
| Z_RISCV_STACK_GUARD_SIZE; |
| #endif /* CONFIG_GEN_PRIV_STACKS */ |
| |
| top_of_user_stack = Z_STACK_PTR_ALIGN( |
| _current->stack_info.start + |
| _current->stack_info.size - |
| _current->stack_info.delta); |
| |
| /* Set next CPU status to user mode */ |
| status = csr_read(mstatus); |
| status = INSERT_FIELD(status, MSTATUS_MPP, PRV_U); |
| status = INSERT_FIELD(status, MSTATUS_MPRV, 0); |
| |
| csr_write(mstatus, status); |
| csr_write(mepc, z_thread_entry_wrapper); |
| |
| /* Set up Physical Memory Protection */ |
| #if defined(CONFIG_PMP_STACK_GUARD) |
| z_riscv_init_stack_guard(_current); |
| #endif |
| |
| z_riscv_init_user_accesses(_current); |
| z_riscv_configure_user_allowed_stack(_current); |
| |
| is_user_mode = true; |
| |
| __asm__ volatile ("mv a0, %1" |
| : "=r" (user_entry) |
| : "r" (user_entry) |
| : "memory"); |
| |
| __asm__ volatile ("mv a1, %1" |
| : "=r" (p1) |
| : "r" (p1) |
| : "memory"); |
| |
| __asm__ volatile ("mv a2, %1" |
| : "=r" (p2) |
| : "r" (p2) |
| : "memory"); |
| |
| __asm__ volatile ("mv a3, %1" |
| : "=r" (p3) |
| : "r" (p3) |
| : "memory"); |
| |
| __asm__ volatile ("mv sp, %1" |
| : "=r" (top_of_user_stack) |
| : "r" (top_of_user_stack) |
| : "memory"); |
| |
| __asm__ volatile ("mret"); |
| |
| CODE_UNREACHABLE; |
| } |
| |
| #endif /* CONFIG_USERSPACE */ |