diff options
| -rw-r--r-- | console.c | 2 | ||||
| -rw-r--r-- | defs.h | 4 | ||||
| -rw-r--r-- | main.c | 4 | ||||
| -rw-r--r-- | proc.c | 118 | ||||
| -rw-r--r-- | string.c | 30 | ||||
| -rw-r--r-- | syscall.c | 13 | ||||
| -rw-r--r-- | trapasm.S | 6 |
7 files changed, 98 insertions, 79 deletions
@@ -58,7 +58,7 @@ real_cons_putc(int c) if((ind / 80) >= 24){ // scroll up - memcpy(crt, crt + 80, sizeof(crt[0]) * (23 * 80)); + memmove(crt, crt + 80, sizeof(crt[0]) * (23 * 80)); ind -= 80; memset(crt + ind, 0, sizeof(crt[0]) * ((24 * 80) - ind)); } @@ -12,7 +12,7 @@ void cons_putc(int); struct proc; struct jmpbuf; void setupsegs(struct proc *); -struct proc * newproc(void); +struct proc * copyproc(struct proc*); struct spinlock; void sleep(void *, struct spinlock *); void wakeup(void *); @@ -32,7 +32,6 @@ void tvinit(void); void idtinit(void); // string.c -void * memcpy(void *dst, void *src, unsigned n); void * memset(void *dst, int c, unsigned n); int memcmp(const void *v1, const void *v2, unsigned n); void *memmove(void *dst, const void *src, unsigned n); @@ -92,3 +91,4 @@ void ide_init(void); void ide_intr(void); void* ide_start_read(uint32_t secno, void *dst, unsigned nsecs); int ide_finish_read(void *); + @@ -81,7 +81,7 @@ main() // become interruptable sti(); - p = newproc(); + p = copyproc(&proc[0]); load_icode(p, _binary_usertests_start, (unsigned) _binary_usertests_size); //load_icode(p, _binary_userfs_start, (unsigned) _binary_userfs_size); @@ -122,7 +122,7 @@ load_icode(struct proc *p, uint8_t *binary, unsigned size) panic("load_icode: icode wants to be above UTOP"); // Load/clear the segment - memcpy(p->mem + ph->p_va, binary + ph->p_offset, ph->p_filesz); + memmove(p->mem + ph->p_va, binary + ph->p_offset, ph->p_filesz); memset(p->mem + ph->p_va + ph->p_filesz, 0, ph->p_memsz - ph->p_filesz); } } @@ -13,6 +13,7 @@ struct proc proc[NPROC]; struct proc *curproc[NCPU]; int next_pid = 1; extern void forkret(void); +extern void forkret1(struct Trapframe*); /* * set up a process's task state and segment descriptors @@ -42,84 +43,87 @@ setupsegs(struct proc *p) p->gdt_pd.pd_base = (unsigned) p->gdt; } -extern void trapret(); +// Look in the process table for an UNUSED proc. +// If found, change state to EMBRYO and return it. +// Otherwise return 0. +struct proc* +allocproc(void) +{ + int i; + struct proc *p; + + for(i = 0; i < NPROC; i++){ + p = &proc[i]; + if(p->state == UNUSED){ + p->state = EMBRYO; + return p; + } + } + return 0; +} -/* - * internal fork(). does not copy kernel stack; instead, - * sets up the stack to return as if from system call. - * caller must set state to RUNNABLE. - */ +// Create a new process copying p as the parent. +// Does not copy the kernel stack. +// Instead, sets up stack to return as if from system call. +// Caller must arrange for process to run (set state to RUNNABLE). struct proc * -newproc() +copyproc(struct proc* p) { + int i; struct proc *np; - struct proc *op; - int fd; + // Allocate process. acquire(&proc_table_lock); - - for(np = &proc[1]; np < &proc[NPROC]; np++){ - if(np->state == UNUSED){ - np->state = EMBRYO; - break; - } - } - if(np >= &proc[NPROC]){ + if((np = allocproc()) == 0){ release(&proc_table_lock); return 0; } - - // copy from proc[0] if we're bootstrapping - op = curproc[cpu()]; - if(op == 0) - op = &proc[0]; - np->pid = next_pid++; - np->ppid = op->pid; - + np->ppid = p->pid; release(&proc_table_lock); - np->sz = op->sz; - np->mem = kalloc(op->sz); - if(np->mem == 0) + // Copy process image memory. + np->sz = p->sz; + np->mem = kalloc(np->sz); + if(np->mem == 0){ + np->state = UNUSED; return 0; - memcpy(np->mem, op->mem, np->sz); + } + memmove(np->mem, p->mem, np->sz); + + // Allocate kernel stack. np->kstack = kalloc(KSTACKSIZE); if(np->kstack == 0){ - kfree(np->mem, op->sz); + kfree(np->mem, np->sz); np->state = UNUSED; return 0; } + + // Initialize segment table. setupsegs(np); + + // Copy trapframe registers from parent. + np->tf = (struct Trapframe*)(np->kstack + KSTACKSIZE) - 1; + *np->tf = *p->tf; - // set up kernel stack to return to user space - np->tf = (struct Trapframe *) (np->kstack + KSTACKSIZE - sizeof(struct Trapframe)); - *(np->tf) = *(op->tf); - np->tf->tf_regs.reg_eax = 0; // so fork() returns 0 in child - - // Set up new jmpbuf to start executing forkret (see trapasm.S) - // with esp pointing at tf. Forkret will call forkret1 (below) to release - // the proc_table_lock and then jump into the usual trap return code. + // Clear %eax so that fork system call returns 0 in child. + np->tf->tf_regs.reg_eax = 0; + + // Set up new jmpbuf to start executing at forkret (see below). memset(&np->jmpbuf, 0, sizeof np->jmpbuf); - np->jmpbuf.jb_eip = (unsigned) forkret; - np->jmpbuf.jb_esp = (unsigned) np->tf - 4; // -4 for the %eip that isn't actually there + np->jmpbuf.jb_eip = (unsigned)forkret; + np->jmpbuf.jb_esp = (unsigned)np->tf; // Copy file descriptors - for(fd = 0; fd < NOFILE; fd++){ - np->fds[fd] = op->fds[fd]; - if(np->fds[fd]) - fd_reference(np->fds[fd]); + for(i = 0; i < NOFILE; i++){ + np->fds[i] = p->fds[i]; + if(np->fds[i]) + fd_reference(np->fds[i]); } return np; } -void -forkret1(void) -{ - release(&proc_table_lock); -} - // Per-CPU process scheduler. // Each CPU calls scheduler() after setting itself up. // Scheduler never returns. It loops, doing: @@ -199,7 +203,7 @@ sched(void) // Give up the CPU for one scheduling round. void -yield() +yield(void) { struct proc *p; @@ -211,6 +215,18 @@ yield() release(&proc_table_lock); } +// A process's very first scheduling by scheduler() +// will longjmp here to do the first jump into user space. +void +forkret(void) +{ + // Still holding proc_table_lock from scheduler. + release(&proc_table_lock); + + // Jump into assembly, never to return. + forkret1(curproc[cpu()]->tf); +} + // Atomically release lock and sleep on chan. // Reacquires lock when reawakened. void @@ -2,18 +2,6 @@ #include "defs.h" void * -memcpy(void *dst, void *src, unsigned n) -{ - char *d = (char *) dst; - char *s = (char *) src; - - while(n-- > 0) - *d++ = *s++; - - return dst; -} - -void * memset(void *dst, int c, unsigned n) { char *d = (char *) dst; @@ -69,3 +57,21 @@ strncmp(const char *p, const char *q, unsigned n) else return (int) ((unsigned char) *p - (unsigned char) *q); } + +// Memcpy is deprecated and should NOT be called. +// Use memmove instead, which has defined semantics +// when the two memory ranges overlap. +// Memcpy is here only because gcc compiles some +// structure assignments into calls to memcpy. +void * +memcpy(void *dst, void *src, unsigned n) +{ + char *d = (char *) dst; + char *s = (char *) src; + + while(n-- > 0) + *d++ = *s++; + + return dst; +} + @@ -30,7 +30,7 @@ fetchint(struct proc *p, unsigned addr, int *ip) if(addr > p->sz - 4) return -1; - memcpy(ip, p->mem + addr, 4); + memmove(ip, p->mem + addr, 4); return 0; } @@ -49,7 +49,7 @@ putint(struct proc *p, unsigned addr, int ip) { if(addr > p->sz - 4) return -1; - memcpy(p->mem + addr, &ip, 4); + memmove(p->mem + addr, &ip, 4); return 0; } @@ -150,13 +150,10 @@ sys_fork(void) { struct proc *np; - np = newproc(); - if(np){ - np->state = RUNNABLE; - return np->pid; - } else { + if((np = copyproc(curproc[cpu()])) == 0) return -1; - } + np->state = RUNNABLE; + return np->pid; } int @@ -30,9 +30,9 @@ trapret: addl $0x8, %esp /* trapno and errcode */ iret -.globl forkret -forkret: - call forkret1 +.globl forkret1 +forkret1: + movl 4(%esp), %esp jmp trapret .globl acpu |