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128 lines
3.5 KiB
128 lines
3.5 KiB
/*
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* contains the implementation of all syscalls.
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*/
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#include <stdint.h>
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#include <errno.h>
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#include "util/types.h"
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#include "syscall.h"
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#include "string.h"
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#include "process.h"
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#include "util/functions.h"
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#include "pmm.h"
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#include "vmm.h"
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#include "sched.h"
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#include "spike_interface/spike_utils.h"
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//
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// implement the SYS_user_print syscall
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//
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ssize_t sys_user_print(const char* buf, size_t n) {
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// buf is now an address in user space of the given app's user stack,
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// so we have to transfer it into phisical address (kernel is running in direct mapping).
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assert( current );
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char* pa = (char*)user_va_to_pa((pagetable_t)(current->pagetable), (void*)buf);
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sprint(pa);
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return 0;
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}
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//
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// implement the SYS_user_exit syscall
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//
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ssize_t sys_user_exit(uint64 code) {
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sprint("User exit with code:%d.\n", code);
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// reclaim the current process, and reschedule. added @lab3_1
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free_process( current );
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schedule();
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return 0;
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}
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//
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// maybe, the simplest implementation of malloc in the world ... added @lab2_2
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//
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uint64 sys_user_allocate_page() {
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void* pa = alloc_page();
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uint64 va;
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// if there are previously reclaimed pages, use them first (this does not change the
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// size of the heap)
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if (current->user_heap.free_pages_count > 0) {
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va = current->user_heap.free_pages_address[--current->user_heap.free_pages_count];
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assert(va < current->user_heap.heap_top);
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} else {
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// otherwise, allocate a new page (this increases the size of the heap by one page)
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va = current->user_heap.heap_top;
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current->user_heap.heap_top += PGSIZE;
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current->mapped_info[HEAP_SEGMENT].npages++;
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}
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user_vm_map((pagetable_t)current->pagetable, va, PGSIZE, (uint64)pa,
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prot_to_type(PROT_WRITE | PROT_READ, 1));
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return va;
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}
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//
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// reclaim a page, indicated by "va". added @lab2_2
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//
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uint64 sys_user_free_page(uint64 va) {
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user_vm_unmap((pagetable_t)current->pagetable, va, PGSIZE, 1);
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// add the reclaimed page to the free page list
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current->user_heap.free_pages_address[current->user_heap.free_pages_count++] = va;
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return 0;
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}
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//
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// kerenl entry point of naive_fork
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//
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ssize_t sys_user_fork() {
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sprint("User call fork.\n");
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return do_fork( current );
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}
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//
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// kerenl entry point of yield. added @lab3_2
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//
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ssize_t sys_user_yield() {
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// TODO (lab3_2): implment the syscall of yield.
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// hint: the functionality of yield is to give up the processor. therefore,
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// we should set the status of currently running process to READY, insert it in
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// the rear of ready queue, and finally, schedule a READY process to run.
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panic( "You need to implement the yield syscall in lab3_2.\n" );
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return 0;
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}
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ssize_t sys_user_printpa(uint64 va)
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{
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uint64 pa = (uint64)user_va_to_pa((pagetable_t)(current->pagetable), (void*)va);
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sprint("%lx\n", pa);
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return 0;
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}
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//
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// [a0]: the syscall number; [a1] ... [a7]: arguments to the syscalls.
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// returns the code of success, (e.g., 0 means success, fail for otherwise)
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//
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long do_syscall(long a0, long a1, long a2, long a3, long a4, long a5, long a6, long a7) {
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switch (a0) {
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case SYS_user_print:
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return sys_user_print((const char*)a1, a2);
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case SYS_user_exit:
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return sys_user_exit(a1);
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// added @lab2_2
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case SYS_user_allocate_page:
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return sys_user_allocate_page();
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case SYS_user_free_page:
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return sys_user_free_page(a1);
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case SYS_user_fork:
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return sys_user_fork();
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case SYS_user_yield:
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return sys_user_yield();
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case SYS_user_printpa:
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return sys_user_printpa(a1);
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default:
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panic("Unknown syscall %ld \n", a0);
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}
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}
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