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提交 856e1fc1 创建 作者: rsc's avatar rsc
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Attempt to clean up newproc somewhat.

Also remove all calls to memcpy in favor of memmove, which has defined semantics when the ranges overlap. The fact that memcpy was working in console.c to scroll the screen is not guaranteed by all implementations.
上级 65bd8e13
隐藏空白字符变更
内嵌 并排
正在显示 包含 98 行增加 和 79 行删除
console.c
浏览文件 @ 856e1fc1
...@@ -58,7 +58,7 @@ real_cons_putc(int c) ...@@ -58,7 +58,7 @@ real_cons_putc(int c)
if((ind / 80) >= 24){ if((ind / 80) >= 24){
// scroll up // scroll up
memcpy(crt, crt + 80, sizeof(crt[0]) * (23 * 80)); memmove(crt, crt + 80, sizeof(crt[0]) * (23 * 80));
ind -= 80; ind -= 80;
memset(crt + ind, 0, sizeof(crt[0]) * ((24 * 80) - ind)); memset(crt + ind, 0, sizeof(crt[0]) * ((24 * 80) - ind));
} }
......
defs.h
浏览文件 @ 856e1fc1
...@@ -12,7 +12,7 @@ void cons_putc(int); ...@@ -12,7 +12,7 @@ void cons_putc(int);
struct proc; struct proc;
struct jmpbuf; struct jmpbuf;
void setupsegs(struct proc *); void setupsegs(struct proc *);
struct proc * newproc(void); struct proc * copyproc(struct proc*);
struct spinlock; struct spinlock;
void sleep(void *, struct spinlock *); void sleep(void *, struct spinlock *);
void wakeup(void *); void wakeup(void *);
...@@ -32,7 +32,6 @@ void tvinit(void); ...@@ -32,7 +32,6 @@ void tvinit(void);
void idtinit(void); void idtinit(void);
// string.c // string.c
void * memcpy(void *dst, void *src, unsigned n);
void * memset(void *dst, int c, unsigned n); void * memset(void *dst, int c, unsigned n);
int memcmp(const void *v1, const void *v2, unsigned n); int memcmp(const void *v1, const void *v2, unsigned n);
void *memmove(void *dst, const void *src, unsigned n); void *memmove(void *dst, const void *src, unsigned n);
...@@ -92,3 +91,4 @@ void ide_init(void); ...@@ -92,3 +91,4 @@ void ide_init(void);
void ide_intr(void); void ide_intr(void);
void* ide_start_read(uint32_t secno, void *dst, unsigned nsecs); void* ide_start_read(uint32_t secno, void *dst, unsigned nsecs);
int ide_finish_read(void *); int ide_finish_read(void *);
main.c
浏览文件 @ 856e1fc1
...@@ -81,7 +81,7 @@ main() ...@@ -81,7 +81,7 @@ main()
// become interruptable // become interruptable
sti(); sti();
p = newproc(); p = copyproc(&proc[0]);
load_icode(p, _binary_usertests_start, (unsigned) _binary_usertests_size); load_icode(p, _binary_usertests_start, (unsigned) _binary_usertests_size);
//load_icode(p, _binary_userfs_start, (unsigned) _binary_userfs_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) ...@@ -122,7 +122,7 @@ load_icode(struct proc *p, uint8_t *binary, unsigned size)
panic("load_icode: icode wants to be above UTOP"); panic("load_icode: icode wants to be above UTOP");
// Load/clear the segment // 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); memset(p->mem + ph->p_va + ph->p_filesz, 0, ph->p_memsz - ph->p_filesz);
} }
} }
proc.c
浏览文件 @ 856e1fc1
...@@ -13,6 +13,7 @@ struct proc proc[NPROC]; ...@@ -13,6 +13,7 @@ struct proc proc[NPROC];
struct proc *curproc[NCPU]; struct proc *curproc[NCPU];
int next_pid = 1; int next_pid = 1;
extern void forkret(void); extern void forkret(void);
extern void forkret1(struct Trapframe*);
/* /*
* set up a process's task state and segment descriptors * set up a process's task state and segment descriptors
...@@ -42,84 +43,87 @@ setupsegs(struct proc *p) ...@@ -42,84 +43,87 @@ setupsegs(struct proc *p)
p->gdt_pd.pd_base = (unsigned) p->gdt; 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;
}
/* // Create a new process copying p as the parent.
* internal fork(). does not copy kernel stack; instead, // Does not copy the kernel stack.
* sets up the stack to return as if from system call. // Instead, sets up stack to return as if from system call.
* caller must set state to RUNNABLE. // Caller must arrange for process to run (set state to RUNNABLE).
*/
struct proc * struct proc *
newproc() copyproc(struct proc* p)
{ {
int i;
struct proc *np; struct proc *np;
struct proc *op;
int fd;
// Allocate process.
acquire(&proc_table_lock); acquire(&proc_table_lock);
if((np = allocproc()) == 0){
for(np = &proc[1]; np < &proc[NPROC]; np++){
if(np->state == UNUSED){
np->state = EMBRYO;
break;
}
}
if(np >= &proc[NPROC]){
release(&proc_table_lock); release(&proc_table_lock);
return 0; return 0;
} }
// copy from proc[0] if we're bootstrapping
op = curproc[cpu()];
if(op == 0)
op = &proc[0];
np->pid = next_pid++; np->pid = next_pid++;
np->ppid = op->pid; np->ppid = p->pid;
release(&proc_table_lock); release(&proc_table_lock);
np->sz = op->sz; // Copy process image memory.
np->mem = kalloc(op->sz); np->sz = p->sz;
if(np->mem == 0) np->mem = kalloc(np->sz);
if(np->mem == 0){
np->state = UNUSED;
return 0; return 0;
memcpy(np->mem, op->mem, np->sz); }
memmove(np->mem, p->mem, np->sz);
// Allocate kernel stack.
np->kstack = kalloc(KSTACKSIZE); np->kstack = kalloc(KSTACKSIZE);
if(np->kstack == 0){ if(np->kstack == 0){
kfree(np->mem, op->sz); kfree(np->mem, np->sz);
np->state = UNUSED; np->state = UNUSED;
return 0; return 0;
} }
// Initialize segment table.
setupsegs(np); 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 // Clear %eax so that fork system call returns 0 in child.
np->tf = (struct Trapframe *) (np->kstack + KSTACKSIZE - sizeof(struct Trapframe)); np->tf->tf_regs.reg_eax = 0;
*(np->tf) = *(op->tf);
np->tf->tf_regs.reg_eax = 0; // so fork() returns 0 in child // Set up new jmpbuf to start executing at forkret (see below).
// 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.
memset(&np->jmpbuf, 0, sizeof np->jmpbuf); memset(&np->jmpbuf, 0, sizeof np->jmpbuf);
np->jmpbuf.jb_eip = (unsigned) forkret; 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_esp = (unsigned)np->tf;
// Copy file descriptors // Copy file descriptors
for(fd = 0; fd < NOFILE; fd++){ for(i = 0; i < NOFILE; i++){
np->fds[fd] = op->fds[fd]; np->fds[i] = p->fds[i];
if(np->fds[fd]) if(np->fds[i])
fd_reference(np->fds[fd]); fd_reference(np->fds[i]);
} }
return np; return np;
} }
void
forkret1(void)
{
release(&proc_table_lock);
}
// Per-CPU process scheduler. // Per-CPU process scheduler.
// Each CPU calls scheduler() after setting itself up. // Each CPU calls scheduler() after setting itself up.
// Scheduler never returns. It loops, doing: // Scheduler never returns. It loops, doing:
...@@ -199,7 +203,7 @@ sched(void) ...@@ -199,7 +203,7 @@ sched(void)
// Give up the CPU for one scheduling round. // Give up the CPU for one scheduling round.
void void
yield() yield(void)
{ {
struct proc *p; struct proc *p;
...@@ -211,6 +215,18 @@ yield() ...@@ -211,6 +215,18 @@ yield()
release(&proc_table_lock); 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. // Atomically release lock and sleep on chan.
// Reacquires lock when reawakened. // Reacquires lock when reawakened.
void void
......
string.c
浏览文件 @ 856e1fc1
...@@ -2,18 +2,6 @@ ...@@ -2,18 +2,6 @@
#include "defs.h" #include "defs.h"
void * 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) memset(void *dst, int c, unsigned n)
{ {
char *d = (char *) dst; char *d = (char *) dst;
...@@ -69,3 +57,21 @@ strncmp(const char *p, const char *q, unsigned n) ...@@ -69,3 +57,21 @@ strncmp(const char *p, const char *q, unsigned n)
else else
return (int) ((unsigned char) *p - (unsigned char) *q); 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;
}
syscall.c
浏览文件 @ 856e1fc1
...@@ -30,7 +30,7 @@ fetchint(struct proc *p, unsigned addr, int *ip) ...@@ -30,7 +30,7 @@ fetchint(struct proc *p, unsigned addr, int *ip)
if(addr > p->sz - 4) if(addr > p->sz - 4)
return -1; return -1;
memcpy(ip, p->mem + addr, 4); memmove(ip, p->mem + addr, 4);
return 0; return 0;
} }
...@@ -49,7 +49,7 @@ putint(struct proc *p, unsigned addr, int ip) ...@@ -49,7 +49,7 @@ putint(struct proc *p, unsigned addr, int ip)
{ {
if(addr > p->sz - 4) if(addr > p->sz - 4)
return -1; return -1;
memcpy(p->mem + addr, &ip, 4); memmove(p->mem + addr, &ip, 4);
return 0; return 0;
} }
...@@ -150,13 +150,10 @@ sys_fork(void) ...@@ -150,13 +150,10 @@ sys_fork(void)
{ {
struct proc *np; struct proc *np;
np = newproc(); if((np = copyproc(curproc[cpu()])) == 0)
if(np){
np->state = RUNNABLE;
return np->pid;
} else {
return -1; return -1;
} np->state = RUNNABLE;
return np->pid;
} }
int int
......
trapasm.S
浏览文件 @ 856e1fc1
...@@ -30,9 +30,9 @@ trapret: ...@@ -30,9 +30,9 @@ trapret:
addl $0x8, %esp /* trapno and errcode */ addl $0x8, %esp /* trapno and errcode */
iret iret
.globl forkret .globl forkret1
forkret: forkret1:
call forkret1 movl 4(%esp), %esp
jmp trapret jmp trapret
.globl acpu .globl acpu
......
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