xv6-65oo2/kernel/syscall.c
Robert Morris 5eb1685700 have kill() lock before looking at p->pid
document wait()'s use of np->parent w/o holding lock.
2019-07-10 09:24:50 -04:00

183 lines
4 KiB
C

#include "types.h"
#include "param.h"
#include "memlayout.h"
#include "riscv.h"
#include "spinlock.h"
#include "proc.h"
#include "syscall.h"
#include "defs.h"
// User code makes a system call with INT T_SYSCALL.
// System call number in %eax.
// Arguments on the stack, from the user call to the C
// library system call function. The saved user %esp points
// to a saved program counter, and then the first argument.
// Fetch the int at addr from the current process.
int
fetchint(uint64 addr, int *ip)
{
struct proc *p = myproc();
if(addr >= p->sz || addr+4 > p->sz)
return -1;
if(copyin(p->pagetable, (char *)ip, addr, sizeof(*ip)) != 0)
return -1;
return 0;
}
// Fetch the uint64 at addr from the current process.
int
fetchaddr(uint64 addr, uint64 *ip)
{
struct proc *p = myproc();
if(addr >= p->sz || addr+sizeof(uint64) > p->sz)
return -1;
if(copyin(p->pagetable, (char *)ip, addr, sizeof(*ip)) != 0)
return -1;
return 0;
}
// Fetch the nul-terminated string at addr from the current process.
// Doesn't actually copy the string - just sets *pp to point at it.
// Returns length of string, not including nul, or -1 for error.
int
fetchstr(uint64 addr, char *buf, int max)
{
struct proc *p = myproc();
int err = copyinstr(p->pagetable, buf, addr, max);
if(err < 0)
return err;
return strlen(buf);
}
static uint64
fetcharg(int n)
{
struct proc *p = myproc();
switch (n) {
case 0:
return p->tf->a0;
case 1:
return p->tf->a1;
case 2:
return p->tf->a2;
case 3:
return p->tf->a3;
case 4:
return p->tf->a4;
case 5:
return p->tf->a5;
}
panic("fetcharg");
return -1;
}
// Fetch the nth 32-bit system call argument.
int
argint(int n, int *ip)
{
*ip = fetcharg(n);
return 0;
}
int
argaddr(int n, uint64 *ip)
{
*ip = fetcharg(n);
return 0;
}
// Fetch the nth word-sized system call argument as a pointer
// to a block of memory of size bytes. Check that the pointer
// lies within the process address space.
int
argptr(int n, uint64 *pp, int size)
{
uint64 i;
struct proc *p = myproc();
if(argaddr(n, &i) < 0)
return -1;
if(size < 0 || (uint)i >= p->sz || (uint)i+size > p->sz)
return -1;
*pp = i;
return 0;
}
// Fetch the nth word-sized system call argument as a null-terminated string.
// Copies into buf, at most max.
// Returns string length if OK (including nul), -1 if error.
int
argstr(int n, char *buf, int max)
{
uint64 addr;
if(argaddr(n, &addr) < 0)
return -1;
return fetchstr(addr, buf, max);
}
extern uint64 sys_chdir(void);
extern uint64 sys_close(void);
extern uint64 sys_dup(void);
extern uint64 sys_exec(void);
extern uint64 sys_exit(void);
extern uint64 sys_fork(void);
extern uint64 sys_fstat(void);
extern uint64 sys_getpid(void);
extern uint64 sys_kill(void);
extern uint64 sys_link(void);
extern uint64 sys_mkdir(void);
extern uint64 sys_mknod(void);
extern uint64 sys_open(void);
extern uint64 sys_pipe(void);
extern uint64 sys_read(void);
extern uint64 sys_sbrk(void);
extern uint64 sys_sleep(void);
extern uint64 sys_unlink(void);
extern uint64 sys_wait(void);
extern uint64 sys_write(void);
extern uint64 sys_uptime(void);
static uint64 (*syscalls[])(void) = {
[SYS_fork] sys_fork,
[SYS_exit] sys_exit,
[SYS_wait] sys_wait,
[SYS_pipe] sys_pipe,
[SYS_read] sys_read,
[SYS_kill] sys_kill,
[SYS_exec] sys_exec,
[SYS_fstat] sys_fstat,
[SYS_chdir] sys_chdir,
[SYS_dup] sys_dup,
[SYS_getpid] sys_getpid,
[SYS_sbrk] sys_sbrk,
[SYS_sleep] sys_sleep,
[SYS_uptime] sys_uptime,
[SYS_open] sys_open,
[SYS_write] sys_write,
[SYS_mknod] sys_mknod,
[SYS_unlink] sys_unlink,
[SYS_link] sys_link,
[SYS_mkdir] sys_mkdir,
[SYS_close] sys_close,
};
void
syscall(void)
{
int num;
struct proc *p = myproc();
num = p->tf->a7;
if(num > 0 && num < NELEM(syscalls) && syscalls[num]) {
//printf("%d: syscall %d\n", p->pid, num);
p->tf->a0 = syscalls[num]();
//printf("%d: syscall %d -> %d\n", p->pid, num, p->tf->a0);
} else {
printf("%d %s: unknown sys call %d\n",
p->pid, p->name, num);
p->tf->a0 = -1;
}
}