111 lines
2.4 KiB
C
111 lines
2.4 KiB
C
#include "types.h"
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#include "param.h"
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#include "mmu.h"
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#include "proc.h"
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#include "defs.h"
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#include "x86.h"
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#include "elf.h"
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int
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exec(char *path, char **argv)
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{
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char *mem, *s, *last;
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int i, argc, arglen, len, off;
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uint sz, sp, spoffset, argp;
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struct elfhdr elf;
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struct inode *ip;
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struct proghdr ph;
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pde_t *pgdir, *oldpgdir;
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pgdir = 0;
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sz = 0;
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if((ip = namei(path)) == 0)
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return -1;
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ilock(ip);
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// Check ELF header
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if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))
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goto bad;
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if(elf.magic != ELF_MAGIC)
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goto bad;
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if (!(pgdir = setupkvm()))
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goto bad;
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// Load program into memory.
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for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){
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if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph))
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goto bad;
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if(ph.type != ELF_PROG_LOAD)
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continue;
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if(ph.memsz < ph.filesz)
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goto bad;
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if (!allocuvm(pgdir, (char *)ph.va, ph.memsz))
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goto bad;
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if(ph.va + ph.memsz > sz)
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sz = ph.va + ph.memsz;
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if (!loaduvm(pgdir, (char *)ph.va, ip, ph.offset, ph.filesz))
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goto bad;
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}
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iunlockput(ip);
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// Allocate and initialize stack at sz
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sz = PGROUNDUP(sz);
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sz += PGSIZE; // leave an invalid page
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if (!allocuvm(pgdir, (char *)sz, PGSIZE))
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goto bad;
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mem = uva2ka(pgdir, (char *)sz);
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spoffset = sz;
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sz += PGSIZE;
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arglen = 0;
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for(argc=0; argv[argc]; argc++)
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arglen += strlen(argv[argc]) + 1;
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arglen = (arglen+3) & ~3;
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sp = sz;
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argp = sz - arglen - 4*(argc+1);
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// Copy argv strings and pointers to stack.
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*(uint*)(mem+argp-spoffset + 4*argc) = 0; // argv[argc]
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for(i=argc-1; i>=0; i--){
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len = strlen(argv[i]) + 1;
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sp -= len;
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memmove(mem+sp-spoffset, argv[i], len);
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*(uint*)(mem+argp-spoffset + 4*i) = sp; // argv[i]
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}
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// Stack frame for main(argc, argv), below arguments.
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sp = argp;
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sp -= 4;
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*(uint*)(mem+sp-spoffset) = argp;
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sp -= 4;
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*(uint*)(mem+sp-spoffset) = argc;
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sp -= 4;
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*(uint*)(mem+sp-spoffset) = 0xffffffff; // fake return pc
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// Save program name for debugging.
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for(last=s=path; *s; s++)
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if(*s == '/')
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last = s+1;
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safestrcpy(proc->name, last, sizeof(proc->name));
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// Commit to the user image.
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oldpgdir = proc->pgdir;
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proc->pgdir = pgdir;
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proc->sz = sz;
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proc->tf->eip = elf.entry; // main
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proc->tf->esp = sp;
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switchuvm(proc);
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freevm(oldpgdir);
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return 0;
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bad:
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if (pgdir) freevm(pgdir);
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iunlockput(ip);
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return -1;
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}
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