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1 #include <string.h>
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2 #include "proc.h"
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3 #include "tss.h"
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4 #include "vm.h"
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5 #include "segm.h"
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6 #include "intr.h"
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7 #include "panic.h"
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8
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9
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10 /* defined in test_proc.S */
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11 void test_proc(void);
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12 void test_proc_end(void);
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13
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14 static struct process proc[MAX_PROC];
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15 static int cur_pid;
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16
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17 void init_proc(void)
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18 {
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19 int proc_size_pg, img_start_pg, stack_pg;
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20 void *img_start;
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21 cur_pid = -1;
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22
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23 /* prepare the first process */
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24
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25 /* allocate a chunk of memory for the process image
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26 * and copy the code of test_proc there.
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27 * (should be mapped at a fixed address)
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28 */
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29 proc_size_pg = (test_proc_end - test_proc) / PGSIZE + 1;
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30 if((img_start_pg = pgalloc(proc_size_pg, MEM_USER)) == -1) {
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31 panic("failed to allocate space for the init process image\n");
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32 }
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33 img_start = (void*)PAGE_TO_ADDR(img_start_pg);
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34 memcpy(img_start, test_proc, proc_size_pg * PGSIZE);
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35
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36 /* instruction pointer at the beginning of the process image */
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37 proc[0].ctx.instr_ptr = (uint32_t)img_start;
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38
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39 /* allocate the first page of the process stack */
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40 stack_pg = ADDR_TO_PAGE(KMEM_START) - 1;
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41 if(pgalloc_vrange(stack_pg, 1) == -1) {
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42 panic("failed to allocate user stack page\n");
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43 }
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44 proc[0].ctx.stack_ptr = PAGE_TO_ADDR(stack_pg) + PGSIZE;
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45
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46 /* create the virtual address space for this process */
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47 proc[0].ctx.pgtbl_paddr = clone_vm();
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48
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49 /* we don't need the image and the stack in this address space */
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50 unmap_page_range(img_start_pg, proc_size_pg);
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51 pgfree(img_start_pg, proc_size_pg);
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52
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53 unmap_page(stack_pg);
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54 pgfree(stack_pg, 1);
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55
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56
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57 /* switch to it by calling a function that takes the context
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58 * of the current process, plugs the values into the interrupt
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59 * stack, and calls iret.
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60 * (should also set ss0/sp0 in TSS before returning)
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61 */
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62 context_switch(0);
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63 /* XXX this will never return */
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64 }
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65
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66
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67 void context_switch(int pid)
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68 {
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69 struct intr_frame ifrm;
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70 struct context *ctx = &proc[pid].ctx;
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71
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72 cur_pid = pid;
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73
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74 ifrm.inum = ifrm.err = 0;
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75
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76 ifrm.regs = ctx->regs;
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77 ifrm.eflags = ctx->flags;
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78
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79 ifrm.eip = ctx->instr_ptr;
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80 ifrm.cs = SEGM_KCODE; /* XXX change this when we setup the TSS */
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81 ifrm.esp = ctx->stack_ptr;
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82 ifrm.ss = SEGM_KDATA; /* XXX */
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83
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84 /* switch to the vm of the process */
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85 set_pgdir_addr(ctx->pgtbl_paddr);
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86
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87 intr_ret(ifrm);
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88 }
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