420 lines
10 KiB
C
420 lines
10 KiB
C
/* Copyright (c) 2017 SiFive Inc. All rights reserved.
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This copyrighted material is made available to anyone wishing to use,
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modify, copy, or redistribute it subject to the terms and conditions
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of the FreeBSD License. This program is distributed in the hope that
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it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
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including the implied warranties of MERCHANTABILITY or FITNESS FOR
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A PARTICULAR PURPOSE. A copy of this license is available at
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http://www.opensource.org/licenses.
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========================================================================
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syscalls.c : Newlib operating system interface
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========================================================================
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This is the maven implementation of the narrow newlib operating
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system interface. It is based on the minimum stubs in the newlib
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documentation, the error stubs in libnosys, and the previous scale
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implementation. Please do not include any additional system calls or
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other functions in this file. Additional header and source files
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should be in the machine subdirectory.
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Here is a list of the functions which make up the operating system
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interface. The file management instructions execute syscall assembly
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instructions so that a proxy kernel (or the simulator) can marshal up
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the request to the host machine. The process management functions are
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mainly just stubs since for now maven only supports a single process.
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- File management functions
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+ open : (v) open file
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+ lseek : (v) set position in file
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+ read : (v) read from file
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+ write : (v) write to file
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+ fstat : (z) status of an open file
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+ stat : (z) status of a file by name
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+ close : (z) close a file
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+ link : (z) rename a file
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+ unlink : (z) remote file's directory entry
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- Process management functions
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+ execve : (z) transfer control to new proc
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+ fork : (z) create a new process
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+ getpid : (v) get process id
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+ kill : (z) send signal to child process
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+ wait : (z) wait for a child process
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- Misc functions
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+ isatty : (v) query whether output stream is a terminal
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+ times : (z) timing information for current process
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+ sbrk : (v) increase program data space
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+ _exit : (-) exit program without cleaning up files
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There are two types of system calls. Those which return a value when
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everything is okay (marked with (v) in above list) and those which
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return a zero when everything is okay (marked with (z) in above
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list). On an error (ie. when the error flag is 1) the return value is
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always an errno which should correspond to the numbers in
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newlib/libc/include/sys/errno.h
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See the newlib documentation for more information
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http://sourceware.org/newlib/libc.html#Syscalls
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*/
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#include <machine/syscall.h>
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#include <sys/stat.h>
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#include <sys/times.h>
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#include <sys/time.h>
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#include <sys/timeb.h>
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#include <errno.h>
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#include <string.h>
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#include <unistd.h>
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#include <utime.h>
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#define syscall_errno(n, a, b, c, d) \
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__internal_syscall(n, (long)(a), (long)(b), (long)(c), (long)(d))
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long
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__syscall_error(long a0)
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{
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errno = -a0;
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return -1;
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}
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/* Open a file. */
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int
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_open(const char *name, int flags, int mode)
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{
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return syscall_errno (SYS_open, name, flags, mode, 0);
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}
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/* Open file relative to given directory. */
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int
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_openat(int dirfd, const char *name, int flags, int mode)
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{
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return syscall_errno (SYS_openat, dirfd, name, flags, mode);
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}
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/* Set position in a file. */
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off_t
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_lseek(int file, off_t ptr, int dir)
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{
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return syscall_errno (SYS_lseek, file, ptr, dir, 0);
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}
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/* Read from a file. */
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ssize_t
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_read(int file, void *ptr, size_t len)
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{
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return syscall_errno (SYS_read, file, ptr, len, 0);
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}
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/* Write to a file. */
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ssize_t
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_write(int file, const void *ptr, size_t len)
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{
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return syscall_errno (SYS_write, file, ptr, len, 0);
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}
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struct kernel_stat
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{
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unsigned long long st_dev;
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unsigned long long st_ino;
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unsigned int st_mode;
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unsigned int st_nlink;
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unsigned int st_uid;
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unsigned int st_gid;
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unsigned long long st_rdev;
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unsigned long long __pad1;
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long long st_size;
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int st_blksize;
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int __pad2;
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long long st_blocks;
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struct timespec st_atim;
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struct timespec st_mtim;
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struct timespec st_ctim;
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int __glibc_reserved[2];
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};
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/* Convert linux's stat64 sturct to newlib's stat. */
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static void
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conv_stat (struct stat *st, struct kernel_stat *kst)
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{
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st->st_dev = kst->st_dev;
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st->st_ino = kst->st_ino;
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st->st_mode = kst->st_mode;
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st->st_nlink = kst->st_nlink;
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st->st_uid = kst->st_uid;
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st->st_gid = kst->st_gid;
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st->st_rdev = kst->st_rdev;
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st->st_size = kst->st_size;
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st->st_blocks = kst->st_blocks;
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st->st_blksize = kst->st_blksize;
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st->st_atime = kst->st_atim.tv_sec;
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st->st_mtime = kst->st_mtim.tv_sec;
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st->st_ctime = kst->st_ctim.tv_sec;
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}
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/* Status of an open file. The sys/stat.h header file required is
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distributed in the include subdirectory for this C library. */
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int
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_fstat(int file, struct stat *st)
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{
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struct kernel_stat kst;
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int rv = syscall_errno (SYS_fstat, file, &kst, 0, 0);
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conv_stat (st, &kst);
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return rv;
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}
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/* Status of a file (by name). */
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int
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_stat(const char *file, struct stat *st)
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{
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struct kernel_stat kst;
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int rv = syscall_errno (SYS_stat, file, &kst, 0, 0);
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conv_stat (st, &kst);
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return rv;
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}
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/* Status of a link (by name). */
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int
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_lstat(const char *file, struct stat *st)
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{
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struct kernel_stat kst;
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int rv = syscall_errno (SYS_lstat, file, &kst, 0, 0);
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conv_stat (st, &kst);
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return rv;
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}
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/* Status of a file (by name) in a given directory. */
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int
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_fstatat(int dirfd, const char *file, struct stat *st, int flags)
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{
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struct kernel_stat kst;
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int rv = syscall_errno (SYS_fstatat, dirfd, file, &kst, flags);
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conv_stat (st, &kst);
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return rv;
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}
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/* Permissions of a file (by name). */
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int
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_access(const char *file, int mode)
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{
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return syscall_errno (SYS_access, file, mode, 0, 0);
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}
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/* Permissions of a file (by name) in a given directory. */
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int
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_faccessat(int dirfd, const char *file, int mode, int flags)
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{
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return syscall_errno (SYS_faccessat, dirfd, file, mode, flags);
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}
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/* Close a file. */
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int
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_close(int file)
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{
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return syscall_errno (SYS_close, file, 0, 0, 0);
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}
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/* Establish a new name for an existing file. */
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int
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_link(const char *old_name, const char *new_name)
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{
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return syscall_errno (SYS_link, old_name, new_name, 0, 0);
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}
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/* Remove a file's directory entry. */
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int
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_unlink(const char *name)
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{
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return syscall_errno (SYS_unlink, name, 0, 0, 0);
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}
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/* Transfer control to a new process. Minimal implementation for a
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system without processes from newlib documentation. */
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int
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_execve(const char *name, char *const argv[], char *const env[])
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{
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errno = ENOMEM;
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return -1;
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}
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/* Create a new process. Minimal implementation for a system without
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processes from newlib documentation. */
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int
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_fork()
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{
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errno = EAGAIN;
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return -1;
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}
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/* Get process id. This is sometimes used to generate strings unlikely
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to conflict with other processes. Minimal implementation for a
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system without processes just returns 1. */
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int
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_getpid()
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{
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return 1;
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}
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/* Send a signal. Minimal implementation for a system without processes
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just causes an error. */
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int
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_kill(int pid, int sig)
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{
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errno = EINVAL;
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return -1;
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}
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/* Wait for a child process. Minimal implementation for a system without
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processes just causes an error. */
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int
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_wait(int *status)
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{
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errno = ECHILD;
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return -1;
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}
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/* Query whether output stream is a terminal. For consistency with the
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other minimal implementations, which only support output to stdout,
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this minimal implementation is suggested by the newlib docs. */
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int
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_isatty(int file)
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{
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struct stat s;
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int ret = _fstat (file, &s);
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return ret == -1 ? -1 : !!(s.st_mode & S_IFCHR);
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}
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/* Get the current time. Only relatively correct. */
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int
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_gettimeofday(struct timeval *tp, void *tz)
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{
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return syscall_errno (SYS_gettimeofday, tp, 0, 0, 0);
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}
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/* Timing information for current process. From
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newlib/libc/include/sys/times.h the tms struct fields are as follows:
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- clock_t tms_utime : user clock ticks
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- clock_t tms_stime : system clock ticks
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- clock_t tms_cutime : children's user clock ticks
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- clock_t tms_cstime : children's system clock ticks
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Since maven does not currently support processes we set both of the
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children's times to zero. Eventually we might want to separately
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account for user vs system time, but for now we just return the total
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number of cycles since starting the program. */
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clock_t
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_times(struct tms *buf)
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{
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// when called for the first time, initialize t0
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static struct timeval t0;
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if(t0.tv_sec == 0)
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_gettimeofday (&t0,0);
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struct timeval t;
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_gettimeofday (&t, 0);
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long long utime = (t.tv_sec - t0.tv_sec) * 1000000 + (t.tv_usec - t0.tv_usec);
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buf->tms_utime = utime * CLOCKS_PER_SEC / 1000000;
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buf->tms_stime = buf->tms_cstime = buf->tms_cutime = 0;
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return -1;
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}
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/* Get the current time. Only relatively correct. */
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int
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_ftime(struct timeb *tp)
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{
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tp->time = tp->millitm = 0;
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return 0;
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}
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/* Stub. */
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int
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_utime(const char *path, const struct utimbuf *times)
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{
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return -1;
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}
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/* Stub. */
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int
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_chown(const char *path, uid_t owner, gid_t group)
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{
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return -1;
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}
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/* Stub. */
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int
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_chmod(const char *path, mode_t mode)
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{
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return -1;
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}
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/* Stub. */
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int
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_chdir(const char *path)
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{
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return -1;
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}
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/* Stub. */
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char *
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_getcwd(char *buf, size_t size)
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{
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return NULL;
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}
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/* Get configurable system variables. */
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long
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_sysconf(int name)
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{
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switch (name)
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{
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case _SC_CLK_TCK:
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return CLOCKS_PER_SEC;
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}
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return -1;
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}
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/* Increase program data space. As malloc and related functions depend
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on this, it is useful to have a working implementation. The following
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is suggested by the newlib docs and suffices for a standalone
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system. */
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void *
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_sbrk(ptrdiff_t incr)
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{
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static unsigned long heap_end;
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if (heap_end == 0)
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{
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long brk = syscall_errno (SYS_brk, 0, 0, 0, 0);
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if (brk == -1)
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return (void *)-1;
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heap_end = brk;
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}
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if (syscall_errno (SYS_brk, heap_end + incr, 0, 0, 0) != heap_end + incr)
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return (void *)-1;
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heap_end += incr;
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return (void *)(heap_end - incr);
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}
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/* Exit a program without cleaning up files. */
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void
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_exit(int exit_status)
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{
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syscall_errno (SYS_exit, exit_status, 0, 0, 0);
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while (1);
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}
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