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79 lines
1.9 KiB
79 lines
1.9 KiB
/*
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* Supervisor-mode startup codes
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*/
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#include "riscv.h"
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#include "string.h"
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#include "elf.h"
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#include "process.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 "memlayout.h"
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#include "spike_interface/spike_utils.h"
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//
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// trap_sec_start points to the beginning of S-mode trap segment (i.e., the entry point of
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// S-mode trap vector). added @lab2_1
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//
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extern char trap_sec_start[];
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//
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// turn on paging. added @lab2_1
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//
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void enable_paging() {
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// write the pointer to kernel page (table) directory into the CSR of "satp".
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write_csr(satp, MAKE_SATP(g_kernel_pagetable));
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// refresh tlb to invalidate its content.
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flush_tlb();
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}
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//
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// load the elf, and construct a "process" (with only a trapframe).
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// load_bincode_from_host_elf is defined in elf.c
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//
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process* load_user_program() {
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process* proc;
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proc = alloc_process();
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sprint("User application is loading.\n");
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load_bincode_from_host_elf(proc);
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return proc;
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}
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//
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// s_start: S-mode entry point of riscv-pke OS kernel.
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//
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int s_start(void) {
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sprint("Enter supervisor mode...\n");
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// in the beginning, we use Bare mode (direct) memory mapping as in lab1.
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// but now, we are going to switch to the paging mode @lab2_1.
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// note, the code still works in Bare mode when calling pmm_init() and kern_vm_init().
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write_csr(satp, 0);
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// init phisical memory manager
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pmm_init();
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// build the kernel page table
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kern_vm_init();
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// now, switch to paging mode by turning on paging (SV39)
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enable_paging();
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// the code now formally works in paging mode, meaning the page table is now in use.
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sprint("kernel page table is on \n");
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// added @lab3_1
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init_proc_pool();
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sprint("Switch to user mode...\n");
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// the application code (elf) is first loaded into memory, and then put into execution
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// added @lab3_1
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insert_to_ready_queue( load_user_program() );
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schedule();
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// we should never reach here.
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return 0;
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}
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