crt.c

Simple Operating Systems （简称SOS）是一个可以运行在X86平台上（包括QEMU

/* Copyright (C) 2005 David Decotigny
   Copyright (C) 2003 Thomas Petazzoni

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; either version 2
   of the License, or (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
   USA. 
*/


/**
 * @file crt.c
 *
 * The C RunTime environment for the basic support of SOS C user
 * programs
 */

#include <hwcore/swintr.h>
#include <string.h>
#include "crt.h"

/**
 * Starter function !
 */
void _start() __attribute__((noreturn));
void _start()
{
  /* This starter function expects a main() function somewhere */
  extern int main();

  /* Reset the bss section */
  extern char _bbss, _ebss;
  memset(& _bbss, 0x0, (& _ebss) - (& _bbss));

  _sos_exit(main());
}


/*
 * By convention, the USER SOS programs always pass 4 arguments to the
 * kernel syscall handler: in eax/../edx. For less arguments, the
 * unused registers are filled with 0s. For more arguments, the 4th
 * syscall parameter gives the address of the array containing the
 * remaining arguments. In any case, eax corresponds to the syscall
 * IDentifier.
 */


inline
int _sos_syscall3(int id,
		  unsigned int arg1,
		  unsigned int arg2,
		  unsigned int arg3)
{
  int ret;

  asm volatile("movl %1,%%eax \n"
	       "movl %2,%%ebx \n"
	       "movl %3,%%ecx \n"
	       "movl %4,%%edx \n"
	       "int  %5\n"
	       "movl %%eax, %0"
	       :"=g"(ret)
	       :"g"(id),"g"(arg1),"g"(arg2),"g"(arg3)
	        ,"i"(SOS_SWINTR_SOS_SYSCALL)
	       :"eax","ebx","ecx","edx");

  return ret;
}


int _sos_syscall0(int id)
{
  return _sos_syscall3(id, 0, 0, 0);
}


int _sos_syscall1(int id,
	     unsigned int arg1)
{
  return _sos_syscall3(id, arg1, 0, 0);
}


int _sos_syscall2(int id,
		  unsigned int arg1,
		  unsigned int arg2)
{
  return _sos_syscall3(id, arg1, arg2, 0);
}


int _sos_syscall4(int id,
		  unsigned int arg1,
		  unsigned int arg2,
		  unsigned int arg3,
		  unsigned int arg4)
{
  unsigned int args[] = { arg3, arg4 };
  return _sos_syscall3(id, arg1, arg2, (unsigned)args);
}


int _sos_syscall5(int id,
		  unsigned int arg1,
		  unsigned int arg2,
		  unsigned int arg3,
		  unsigned int arg4,
		  unsigned int arg5)
{
  unsigned int args[] = { arg3, arg4, arg5 };
  return _sos_syscall3(id, arg1, arg2, (unsigned)args);
}


int _sos_syscall6(int id,
		  unsigned int arg1,
		  unsigned int arg2,
		  unsigned int arg3,
		  unsigned int arg4,
		  unsigned int arg5,
		  unsigned int arg6)
{
  unsigned int args[] = { arg3, arg4, arg5, arg6 };
  return _sos_syscall3(id, arg1, arg2, (unsigned)args);
}


int _sos_syscall7(int id,
		  unsigned int arg1,
		  unsigned int arg2,
		  unsigned int arg3,
		  unsigned int arg4,
		  unsigned int arg5,
		  unsigned int arg6,
		  unsigned int arg7)
{
  unsigned int args[] = { arg3, arg4, arg5, arg6, arg7 };
  return _sos_syscall3(id, arg1, arg2, (unsigned)args);
}


int _sos_syscall8(int id,
		  unsigned int arg1,
		  unsigned int arg2,
		  unsigned int arg3,
		  unsigned int arg4,
		  unsigned int arg5,
		  unsigned int arg6,
		  unsigned int arg7,
		  unsigned int arg8)
{
  unsigned int args[] = { arg3, arg4, arg5, arg6, arg7, arg8 };
  return _sos_syscall3(id, arg1, arg2, (unsigned)args);
}


void _sos_exit(int status)
{
  _sos_syscall1(SOS_SYSCALL_ID_EXIT, (unsigned)status);
  
  /* Never reached ! */
  for ( ; ; )
    ;
}


int _sos_bochs_write(const char * str, unsigned length)
{
  return _sos_syscall2(SOS_SYSCALL_ID_BOCHS_WRITE,
		       (unsigned)str,
		       length);
}


int _sos_fork()
{
  return _sos_syscall0(SOS_SYSCALL_ID_FORK);
}


int _sos_exec(const char * prog)
{
  return _sos_syscall2(SOS_SYSCALL_ID_EXEC, (unsigned int)prog,
		       (unsigned int)strlen(prog));
}


int _sos_fakemmap(void ** ptr_hint_addr, size_t len, int prot, int flags,
		  const char *resource_path, loff_t offset)
{
  return _sos_syscall7(SOS_SYSCALL_ID_FAKEMMAP,
		       (unsigned int)ptr_hint_addr, len, prot, flags,
		       (unsigned int)resource_path,
		       /* offs64_hi */(offset >> 32),
		       /* offs64_lo */(offset & 0xffffffff));
}


int _sos_munmap(void * start, size_t length)
{
  return _sos_syscall2(SOS_SYSCALL_ID_MUNMAP,
		       (unsigned int)start,
		       length);
}


int _sos_mprotect(const void *addr, size_t len, int prot)
{
  return _sos_syscall3(SOS_SYSCALL_ID_MPROTECT,
		       (unsigned int)addr,
		       len,
		       (unsigned int)prot);
}


int _sos_mresize(void * old_addr, size_t old_len,
		 void * *new_addr, size_t new_len,
		 unsigned long flags)
{
  return _sos_syscall5(SOS_SYSCALL_ID_MRESIZE,
		       (unsigned int)old_addr,
		       old_len,
		       (unsigned int)new_addr,
		       new_len,
		       flags);
}


/**
 * Helper function that represents the start routine of a new user
 * thread created from user space (syscall new_thread). It takes 2
 * arguments that are passsed in the eax/ebx registers (@see
 * cpu_ustate_init() in hwcore/cpu_context.c): the start function of
 * the new thread (eax), the argument passed to it (ebx).
 */
static void thread_routine()
{
  /* NOTE: variables as named registers is a gcc extension */
  register unsigned long int reg_arg1 asm("%eax");
  register unsigned long int reg_arg2 asm("%ebx");

  sos_thread_func_t * func = (sos_thread_func_t*)reg_arg1;
  unsigned long int arg = reg_arg2;

  func(arg);
  _sos_exit(0);
}


int _sos_new_thread(sos_thread_func_t *func,
		    void* arg,
		    size_t stack_size)
{
  return _sos_syscall4(SOS_SYSCALL_ID_NEW_THREAD,
		       (unsigned)thread_routine,
		       (unsigned)func, (unsigned)arg,
		       stack_size);
}


int _sos_nanosleep(unsigned long int sec,
		   unsigned long int nanosec)
{
  return _sos_syscall2(SOS_SYSCALL_ID_NANOSLEEP,
		       sec, nanosec);
}


void * _sos_brk(void * new_top_address)
{
  return (void*)_sos_syscall1(SOS_SYSCALL_ID_BRK,
			      (unsigned)new_top_address);
}


int _sos_mount(const char *source, const char *target,
	       const char *filesystemtype, unsigned long mountflags,
	       const char *args)
{
  if (!target || !filesystemtype)
    return -1;

  return _sos_syscall7(SOS_SYSCALL_ID_MOUNT,
		       (unsigned int)source, source?strlen(source):0,
		       (unsigned int)target, strlen(target),
		       (unsigned int)filesystemtype,
		       mountflags,
		       (unsigned int)args);
}


int _sos_umount(const char *target)
{
  if (!target)
    return -1;

  return _sos_syscall2(SOS_SYSCALL_ID_UMOUNT,
		       (unsigned int)target,
		       strlen(target));
}


void _sos_sync(void)
{
  _sos_syscall0(SOS_SYSCALL_ID_SYNC);
}


int _sos_statvfs(const char *path, struct statvfs *buf)
{
  if (! path)
    return -1;
    
  return _sos_syscall3(SOS_SYSCALL_ID_VFSTAT64,
		       (unsigned)path,
		       strlen(path),
		       (unsigned)buf);
}


int _sos_open(const char * pathname, int flags, int mode)
{
  if (! pathname)
    return -1;
    
  return _sos_syscall4(SOS_SYSCALL_ID_OPEN,
		       (unsigned)pathname,
		       strlen(pathname),
		       flags,
		       mode);
}


int _sos_close(int fd)
{
  return _sos_syscall1(SOS_SYSCALL_ID_CLOSE, fd);
}


int _sos_read(int fd, char * buf, size_t * len)
{
  return _sos_syscall3(SOS_SYSCALL_ID_READ, fd,
		       (unsigned int) buf,
		       (unsigned int) len);
}


int _sos_write(int fd, const char * buf, size_t * len)
{
  return _sos_syscall3(SOS_SYSCALL_ID_WRITE, fd,
		       (unsigned int) buf,
		       (unsigned int) len);
}


int _sos_seek64(int fd, loff_t * offset, int whence)
{
  return _sos_syscall3(SOS_SYSCALL_ID_SEEK64, fd,
		       (unsigned int)offset,
		       (unsigned int)whence);
}


int _sos_fmmap(void ** ptr_hint_addr, size_t len, int prot, int flags,
	       int fd, loff_t offset)
{
  return _sos_syscall7(SOS_SYSCALL_ID_FSMMAP,
		       (unsigned int)ptr_hint_addr, len, prot, flags,
		       (unsigned int)fd,
		       /* offs64_hi */(offset >> 32),
		       /* offs64_lo */(offset & 0xffffffff));
}


int _sos_ftruncate64(int fd, loff_t length)
{
  return _sos_syscall2(SOS_SYSCALL_ID_FTRUNCATE64, fd,
		       (unsigned int)length);  
}


int _sos_fcntl(int fd, int cmd, int arg)
{
  return _sos_syscall3(SOS_SYSCALL_ID_FCNTL, fd,
		       (unsigned int)cmd,
		       (unsigned int)arg);
}


int _sos_creat(const char *pathname, int mode)
{
  if (! pathname)
    return -1;

  return _sos_syscall3(SOS_SYSCALL_ID_CREAT,
		       (unsigned int)pathname,
		       strlen(pathname),
		       mode);
}


int _sos_link (const char *oldpath, const char *newpath)
{
  if (!oldpath || !newpath)
    return -1;

  return _sos_syscall4(SOS_SYSCALL_ID_LINK,
		       (unsigned int)oldpath,
		       strlen(oldpath),
		       (unsigned int)newpath,
		       strlen(newpath));
}


int _sos_unlink(const char *pathname)
{
  if (! pathname)
    return -1;

  return _sos_syscall2(SOS_SYSCALL_ID_UNLINK,
		       (unsigned int)pathname,
		       strlen(pathname));
}


int _sos_rename (const char *oldpath, const char *newpath)
{
  if (!oldpath || !newpath)
    return -1;

  return _sos_syscall4(SOS_SYSCALL_ID_RENAME,
		       (unsigned int)oldpath,
		       strlen(oldpath),
		       (unsigned int)newpath,
		       strlen(newpath));
}


int _sos_symlink(const char *target, const char *path)
{
  if (!path || !target)
    return -1;

  return _sos_syscall4(SOS_SYSCALL_ID_SYMLINK,
		       (unsigned int)path,
		       strlen(path),
		       (unsigned int)target,
		       strlen(target));
}


struct dirent; /* Forward declaration */
int _sos_readdir(int fd, struct dirent * dirent)
{
  return _sos_syscall2(SOS_SYSCALL_ID_READDIR,
		       fd,
		       (unsigned int)dirent);
}


int _sos_mkdir(const char *pathname, mode_t mode)
{
  if (!pathname)
    return -1;

  return _sos_syscall3(SOS_SYSCALL_ID_MKDIR,
		       (unsigned int)pathname,
		       strlen(pathname),
		       mode);
}


int _sos_rmdir(const char *pathname)
{
  if (!pathname)
    return -1;

  return _sos_syscall2(SOS_SYSCALL_ID_RMDIR,
		       (unsigned int)pathname,
		       strlen(pathname));
}


int _sos_chmod(const char *pathname, mode_t mode)
{
  if (!pathname)
    return -1;

  return _sos_syscall3(SOS_SYSCALL_ID_CHMOD,
		       (unsigned int)pathname,
		       strlen(pathname),
		       mode);
}


int _sos_stat(const char *pathname, int nofollow, struct stat * st)
{
  if (!pathname || !st)
    return -1;

  return _sos_syscall4(SOS_SYSCALL_ID_STAT64,
		       (unsigned int)pathname,
		       strlen(pathname),
		       nofollow,
		       (unsigned int)st);
}


int _sos_chroot(const char *dirname)
{
  if (!dirname)
    return -1;

  return _sos_syscall2(SOS_SYSCALL_ID_CHROOT,
		       (unsigned int)dirname,
		       strlen(dirname));
}


int _sos_chdir(const char *dirname)
{
  if (!dirname)
    return -1;

  return _sos_syscall2(SOS_SYSCALL_ID_CHDIR,
		       (unsigned int)dirname,
		       strlen(dirname));
}


int _sos_fchdir(int fd)
{
  return _sos_syscall1(SOS_SYSCALL_ID_FCHDIR,
		       (unsigned int)fd);
}