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