274 lines
6.1 KiB
C
274 lines
6.1 KiB
C
/*
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* Copyright (c) 2006-2023 Ali Mashtizadeh
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* All rights reserved.
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*/
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#include <stdbool.h>
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#include <stdint.h>
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#include <string.h>
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#include <sys/kassert.h>
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#include <sys/sysctl.h>
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#include <sys/kmem.h>
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#include <sys/queue.h>
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#include <sys/disk.h>
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#include <sys/elf64.h>
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#include <machine/amd64.h>
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#include <machine/trap.h>
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#include <machine/pmap.h>
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#include <sys/thread.h>
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#include <sys/spinlock.h>
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#include <sys/loader.h>
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#include <sys/vfs.h>
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extern Handle *Console_OpenHandle();
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/**
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* Loader_CheckHeader --
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*
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* Check that the program has a valid ELF header.
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*/
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bool
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Loader_CheckHeader(const Elf64_Ehdr *ehdr)
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{
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if (ehdr->e_ident[EI_MAG0] != ELFMAG0 ||
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ehdr->e_ident[EI_MAG1] != ELFMAG1 ||
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ehdr->e_ident[EI_MAG2] != ELFMAG2 ||
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ehdr->e_ident[EI_MAG3] != ELFMAG3)
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return false;
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if (ehdr->e_ident[EI_CLASS] != ELFCLASS64) {
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return false;
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}
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if (ehdr->e_machine != EM_AMD64) {
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return false;
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}
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return true;
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}
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/**
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* LoaderLoadSegment --
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*
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* Loads a single segment into the target address space. This function loads a
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* single page at a time because it has to lookup the address mappings through
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* the page tables.
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*/
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static void
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LoaderLoadSegment(AS *as, VNode *vn, uintptr_t vaddr,
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uintptr_t offset, uintptr_t len)
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{
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void *raddr;
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if ((vaddr % PGSIZE) != 0) {
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uintptr_t maxlen = PGSIZE - (vaddr % PGSIZE);
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uintptr_t rlen = maxlen < len ? maxlen : len;
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raddr = (void *)DMPA2VA(PMap_Translate(as, vaddr));
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VFS_Read(vn, raddr, offset, rlen);
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vaddr += rlen;
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offset += rlen;
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len -= rlen;
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}
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while (len > PGSIZE) {
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raddr = (void *)DMPA2VA(PMap_Translate(as, vaddr));
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VFS_Read(vn, raddr, offset, PGSIZE);
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vaddr += PGSIZE;
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offset += PGSIZE;
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len -= PGSIZE;
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}
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if (len > 0) {
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raddr = (void *)DMPA2VA(PMap_Translate(as, vaddr));
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VFS_Read(vn, raddr, offset, len);
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}
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}
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/**
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* LoaderZeroSegment --
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*
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* Zeroes a segment of memory in the target address space. This is done one
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* page a time while translating the virtual address to physical.
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*/
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static void
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LoaderZeroSegment(AS *as, uintptr_t vaddr, uintptr_t len)
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{
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void *raddr;
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if ((vaddr % PGSIZE) != 0) {
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uintptr_t maxlen = PGSIZE - (vaddr % PGSIZE);
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uintptr_t rlen = maxlen < len ? maxlen : len;
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raddr = (void *)DMPA2VA(PMap_Translate(as, vaddr));
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memset(raddr, 0, rlen);
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vaddr += rlen;
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len -= rlen;
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}
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while (len > PGSIZE) {
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raddr = (void *)DMPA2VA(PMap_Translate(as, vaddr));
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memset(raddr, 0, PGSIZE);
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vaddr += PGSIZE;
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len -= PGSIZE;
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}
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if (len > 0) {
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raddr = (void *)DMPA2VA(PMap_Translate(as, vaddr));
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memset(raddr, 0, len);
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}
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}
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/**
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* Loader_Load --
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*
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* Load the ELF binary into the process belonging to the thread.
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*/
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bool
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Loader_Load(Thread *thr, VNode *vn, void *buf, uint64_t len)
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{
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int i;
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const Elf64_Ehdr *ehdr;
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const Elf64_Phdr *phdr;
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AS *as = thr->space;
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ehdr = (const Elf64_Ehdr *)(buf);
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phdr = (const Elf64_Phdr *)(buf + ehdr->e_phoff);
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if (!Loader_CheckHeader(ehdr)) {
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Log(loader, "Not a valid executable!\n");
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return false;
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}
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Log(loader, "%8s %16s %8s %8s\n", "Offset", "VAddr", "FileSize", "MemSize");
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for (i = 0; i < ehdr->e_phnum; i++)
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{
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ASSERT(phdr[i].p_type != PT_DYNAMIC);
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if (phdr[i].p_type == PT_LOAD) {
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uint64_t va = phdr[i].p_vaddr;
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uint64_t memsz = phdr[i].p_memsz;
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Log(loader, "%08llx %016llx %08llx %08llx\n", phdr[i].p_offset,
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phdr[i].p_vaddr, phdr[i].p_filesz, phdr[i].p_memsz);
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// Make sure it is page aligned
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va = va & ~(uint64_t)PGMASK;
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memsz += phdr[i].p_vaddr - va;
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Log(loader, "AllocMap %016llx %08llx\n", va, memsz);
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if (!PMap_AllocMap(as, va, memsz, PTE_W)) {
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// XXX: Cleanup!
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ASSERT(false);
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return false;
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}
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}
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}
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PMap_AllocMap(as, MEM_USERSPACE_STKBASE, MEM_USERSPACE_STKLEN, PTE_W);
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for (i = 0; i < ehdr->e_phnum; i++)
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{
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ASSERT(phdr[i].p_type != PT_DYNAMIC);
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if (phdr[i].p_type == PT_LOAD) {
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if (phdr[i].p_filesz != 0) {
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LoaderLoadSegment(as, vn, phdr[i].p_vaddr,
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phdr[i].p_offset, phdr[i].p_filesz);
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}
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LoaderZeroSegment(as,
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phdr[i].p_vaddr + phdr[i].p_filesz,
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phdr[i].p_memsz - phdr[i].p_filesz);
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}
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}
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/* Save the process entry point (i.e., _start) */
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thr->proc->entrypoint = ehdr->e_entry;
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return true;
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}
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/**
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* Loader_LoadInit --
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*
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* The init process is created from the execution kernel thread that
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* initializes the system. This function initializes the thread and process
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* state then loads the init binary.
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*/
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void
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Loader_LoadInit()
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{
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int status;
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void *pg;
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VNode *initvn;
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pg = PAlloc_AllocPage();
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if (!pg)
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Panic("Not enough memory!");
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initvn = VFS_Lookup("/sbin/init");
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status = VFS_Open(initvn);
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if (status < 0)
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Panic("Loading init process failed!");
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status = VFS_Read(initvn, pg, 0, 1024);
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if (status < 0)
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Panic("Reading init process failed!");
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Thread *thr = Sched_Current();
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// Open stdin/out/err
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Handle *handle = Console_OpenHandle();
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Handle_Add(thr->proc, handle);
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handle = Console_OpenHandle();
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Handle_Add(thr->proc, handle);
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handle = Console_OpenHandle();
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Handle_Add(thr->proc, handle);
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/*
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* Load init binary
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*/
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Loader_Load(thr, initvn, pg, 1024);
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VFS_Close(initvn);
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Log(loader, "Jumping to userspace\n");
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/*
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* Reload the page tables for the current process
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*/
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PMap_LoadAS(thr->space); // Reload CR3
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/*
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* Pass in zero arguments with null pointers to init
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*/
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uintptr_t ap[3];
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ap[0] = 0;
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ap[1] = 0;
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ap[2] = 0xDEADBEEF;
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uintptr_t rsp = MEM_USERSPACE_STKTOP - PGSIZE;
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Copy_Out(&ap[0], rsp, sizeof(uintptr_t)*3);
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/*
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* The last step is to return into userspace handing control to init. We
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* create a valid trap frame and return into userspace using Trap_Pop().
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*/
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TrapFrame tf;
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memset(&tf, 0, sizeof(tf));
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tf.ds = SEL_UDS | 3;
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tf.rip = thr->proc->entrypoint;
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tf.cs = SEL_UCS | 3;
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tf.rsp = rsp;
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tf.ss = SEL_UDS | 3;
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tf.rflags = RFLAGS_IF;
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tf.rdi = rsp;
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Trap_Pop(&tf);
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/*
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* We should never reach this point!
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*/
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Panic("Unreachable: Trap_Pop() returned!\n");
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}
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