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Now using a truly minimalist syscalls.c

This commit is contained in:
Clifford Wolf 2016-05-05 15:13:48 +02:00
parent a0d63ea588
commit b2bcf143cb
2 changed files with 98 additions and 846 deletions
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472
scripts/csmith/syscalls.c
View File

@ -1,447 +1,80 @@
// An extremely minimalist syscalls.c for newlib
// Based on riscv newlib libgloss/riscv/machine/syscall.h
// Changes by Clifford Wolf
//========================================================================
// syscalls.c : Newlib operating system interface
//========================================================================
// This is the maven implementation of the narrow newlib operating
// system interface. It is based on the minimum stubs in the newlib
// documentation, the error stubs in libnosys, and the previous scale
// implementation. Please do not include any additional system calls or
// other functions in this file. Additional header and source files
// should be in the machine subdirectory.
//
// Here is a list of the functions which make up the operating system
// interface. The file management instructions execute syscall assembly
// instructions so that a proxy kernel (or the simulator) can marshal up
// the request to the host machine. The process management functions are
// mainly just stubs since for now maven only supports a single process.
//
// - File management functions
// + open : (v) open file
// + lseek : (v) set position in file
// + read : (v) read from file
// + write : (v) write to file
// + fstat : (z) status of an open file
// + stat : (z) status of a file by name
// + close : (z) close a file
// + link : (z) rename a file
// + unlink : (z) remote file's directory entry
//
// - Process management functions
// + execve : (z) transfer control to new proc
// + fork : (z) create a new process
// + getpid : (v) get process id
// + kill : (z) send signal to child process
// + wait : (z) wait for a child process
//
// - Misc functions
// + isatty : (v) query whether output stream is a terminal
// + times : (z) timing information for current process
// + sbrk : (v) increase program data space
// + _exit : (-) exit program without cleaning up files
//
// There are two types of system calls. Those which return a value when
// everything is okay (marked with (v) in above list) and those which
// return a zero when everything is okay (marked with (z) in above
// list). On an error (ie. when the error flag is 1) the return value is
// always an errno which should correspond to the numbers in
// newlib/libc/include/sys/errno.h
//
// Note that really I think we are supposed to define versions of these
// functions with an underscore prefix (eg. _open). This is what some of
// the newlib documentation says, and all the newlib code calls the
// underscore version. This is because technically I don't think we are
// supposed to pollute the namespace with these function names. If you
// define MISSING_SYSCALL_NAMES in xcc/src/newlib/configure.host
// then xcc/src/newlib/libc/include/_syslist.h will essentially define
// all of the underscore versions to be equal to the non-underscore
// versions. I tried not defining MISSING_SYSCALL_NAMES, and newlib
// compiled fine but libstdc++ complained about not being able to fine
// write, read, etc. So for now we do not use underscores (and we do
// define MISSING_SYSCALL_NAMES).
//
// See the newlib documentation for more information
// http://sourceware.org/newlib/libc.html#Syscalls
// Written by Clifford Wolf.
#include <sys/stat.h>
#include <sys/times.h>
#include <sys/time.h>
#include <sys/timeb.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <utime.h>
#include <errno.h>
//------------------------------------------------------------------------
// environment
//------------------------------------------------------------------------
// A pointer to a list of environment variables and their values. For a
// minimal environment, this empty list is adequate. We used to define
// environ here but it is already defined in
// xcc/src/newlib/libc/stdlib/environ.c so to avoid multiple definition
// errors we have commented this out for now.
//
// char* __env[1] = { 0 };
// char** environ = __env;
//------------------------------------------------------------------------
// open
//------------------------------------------------------------------------
// Open a file.
#define UNIMPL_FUNC(_f) ".globl " #_f "\n.type " #_f ", @function\n" #_f ":\n"
int open(const char* name, int flags, int mode)
asm (
".text\n"
".align 2\n"
UNIMPL_FUNC(open)
UNIMPL_FUNC(openat)
UNIMPL_FUNC(lseek)
UNIMPL_FUNC(stat)
UNIMPL_FUNC(lstat)
UNIMPL_FUNC(fstatat)
UNIMPL_FUNC(isatty)
UNIMPL_FUNC(access)
UNIMPL_FUNC(faccessat)
UNIMPL_FUNC(link)
UNIMPL_FUNC(unlink)
UNIMPL_FUNC(execve)
UNIMPL_FUNC(getpid)
UNIMPL_FUNC(fork)
UNIMPL_FUNC(kill)
UNIMPL_FUNC(wait)
UNIMPL_FUNC(times)
UNIMPL_FUNC(gettimeofday)
UNIMPL_FUNC(ftime)
UNIMPL_FUNC(utime)
UNIMPL_FUNC(chown)
UNIMPL_FUNC(chmod)
UNIMPL_FUNC(chdir)
UNIMPL_FUNC(getcwd)
UNIMPL_FUNC(sysconf)
"j unimplemented_syscall\n"
);
void unimplemented_syscall()
{
errno = ENOENT;
return -1;
const char *p = "Unimplemented system call called!\n";
while (*p)
*(volatile int*)0x10000000 = *(p++);
asm volatile ("sbreak");
__builtin_unreachable();
}
//------------------------------------------------------------------------
// openat
//------------------------------------------------------------------------
// Open file relative to given directory
int openat(int dirfd, const char* name, int flags, int mode)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// lseek
//------------------------------------------------------------------------
// Set position in a file.
off_t lseek(int file, off_t ptr, int dir)
{
errno = ESPIPE;
return -1;
}
//----------------------------------------------------------------------
// read
//----------------------------------------------------------------------
// Read from a file.
ssize_t read(int file, void *ptr, size_t len)
{
// always EOF
return 0;
}
//------------------------------------------------------------------------
// write
//------------------------------------------------------------------------
// Write to a file.
ssize_t write(int file, const void *ptr, size_t len)
{
unsigned int *p = (unsigned int*)0x10000000;
const void *eptr = ptr + len;
while (ptr != eptr)
*p = *(char*)(ptr++);
*(volatile int*)0x10000000 = *(char*)(ptr++);
return len;
}
//------------------------------------------------------------------------
// fstat
//------------------------------------------------------------------------
// Status of an open file. The sys/stat.h header file required is
// distributed in the include subdirectory for this C library.
int close(int file)
{
// close is called before _exit()
return 0;
}
int fstat(int file, struct stat *st)
{
// fstat is called during libc startup
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// stat
//------------------------------------------------------------------------
// Status of a file (by name).
int stat(const char *file, struct stat *st)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// lstat
//------------------------------------------------------------------------
// Status of a link (by name).
int lstat(const char *file, struct stat *st)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// fstatat
//------------------------------------------------------------------------
// Status of a file (by name) in a given directory.
int fstatat(int dirfd, const char *file, struct stat *st, int flags)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// access
//------------------------------------------------------------------------
// Permissions of a file (by name).
int access(const char *file, int mode)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// faccessat
//------------------------------------------------------------------------
// Permissions of a file (by name) in a given directory.
int faccessat(int dirfd, const char *file, int mode, int flags)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// close
//------------------------------------------------------------------------
// Close a file.
int close(int file)
{
// close is always ok
return 0;
}
//------------------------------------------------------------------------
// link
//------------------------------------------------------------------------
// Establish a new name for an existing file.
int link(const char *old_name, const char *new_name)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// unlink
//------------------------------------------------------------------------
// Remove a file's directory entry.
int unlink(const char *name)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// execve
//------------------------------------------------------------------------
// Transfer control to a new process. Minimal implementation for a
// system without processes from newlib documentation.
int execve(const char *name, char *const argv[], char *const env[])
{
errno = ENOMEM;
return -1;
}
//------------------------------------------------------------------------
// fork
//------------------------------------------------------------------------
// Create a new process. Minimal implementation for a system without
// processes from newlib documentation.
int fork()
{
errno = EAGAIN;
return -1;
}
//------------------------------------------------------------------------
// getpid
//------------------------------------------------------------------------
// Get process id. This is sometimes used to generate strings unlikely
// to conflict with other processes. Minimal implementation for a
// system without processes just returns 1.
int getpid()
{
return 1;
}
//------------------------------------------------------------------------
// kill
//------------------------------------------------------------------------
// Send a signal. Minimal implementation for a system without processes
// just causes an error.
int kill(int pid, int sig)
{
errno = EINVAL;
return -1;
}
//------------------------------------------------------------------------
// wait
//------------------------------------------------------------------------
// Wait for a child process. Minimal implementation for a system without
// processes just causes an error.
int wait(int *status)
{
errno = ECHILD;
return -1;
}
//------------------------------------------------------------------------
// isatty
//------------------------------------------------------------------------
// Query whether output stream is a terminal. For consistency with the
// other minimal implementations, which only support output to stdout,
// this minimal implementation is suggested by the newlib docs.
int isatty(int file)
{
return 1;
}
//------------------------------------------------------------------------
// times
//------------------------------------------------------------------------
// Timing information for current process. From
// newlib/libc/include/sys/times.h the tms struct fields are as follows:
//
// - clock_t tms_utime : user clock ticks
// - clock_t tms_stime : system clock ticks
// - clock_t tms_cutime : children's user clock ticks
// - clock_t tms_cstime : children's system clock ticks
//
// Since maven does not currently support processes we set both of the
// children's times to zero. Eventually we might want to separately
// account for user vs system time, but for now we just return the total
// number of cycles since starting the program.
clock_t times(struct tms *buf)
{
// when called for the first time, initialize t0
static struct timeval t0;
if (t0.tv_sec == 0)
gettimeofday(&t0, 0);
struct timeval t;
gettimeofday(&t, 0);
long long utime = (t.tv_sec - t0.tv_sec) * 1000000 + (t.tv_usec - t0.tv_usec);
buf->tms_utime = utime * CLOCKS_PER_SEC / 1000000;
buf->tms_stime = buf->tms_cstime = buf->tms_cutime = 0;
return -1;
}
//----------------------------------------------------------------------
// gettimeofday
//----------------------------------------------------------------------
// Get the current time. Only relatively correct.
int gettimeofday(struct timeval *tp, void *tzp)
{
asm volatile ("sbreak");
__builtin_unreachable();
}
//----------------------------------------------------------------------
// ftime
//----------------------------------------------------------------------
// Get the current time. Only relatively correct.
int ftime(struct timeb *tp)
{
tp->time = tp->millitm = 0;
return 0;
}
//----------------------------------------------------------------------
// utime
//----------------------------------------------------------------------
// Stub.
int utime(const char *path, const struct utimbuf *times)
{
return -1;
}
//----------------------------------------------------------------------
// chown
//----------------------------------------------------------------------
// Stub.
int chown(const char *path, uid_t owner, gid_t group)
{
return -1;
}
//----------------------------------------------------------------------
// chmod
//----------------------------------------------------------------------
// Stub.
int chmod(const char *path, mode_t mode)
{
return -1;
}
//----------------------------------------------------------------------
// chdir
//----------------------------------------------------------------------
// Stub.
int chdir(const char *path)
{
return -1;
}
//----------------------------------------------------------------------
// getcwd
//----------------------------------------------------------------------
// Stub.
char *getcwd(char *buf, size_t size)
{
return NULL;
}
//----------------------------------------------------------------------
// sysconf
//----------------------------------------------------------------------
// Get configurable system variables
long sysconf(int name)
{
switch (name) {
case _SC_CLK_TCK:
return CLOCKS_PER_SEC;
}
return -1;
}
//----------------------------------------------------------------------
// sbrk
//----------------------------------------------------------------------
// Increase program data space. As malloc and related functions depend
// on this, it is useful to have a working implementation. The following
// is suggested by the newlib docs and suffices for a standalone
// system.
void *sbrk(ptrdiff_t incr)
{
extern unsigned char _end[]; // Defined by linker
@ -450,20 +83,13 @@ void *sbrk(ptrdiff_t incr)
if (heap_end == 0)
heap_end = (long)_end;
// if (syscall_errno(SYS_brk, heap_end + incr, 0, 0, 0) != heap_end + incr)
// return (void *)-1;
heap_end += incr;
return (void *)(heap_end - incr);
}
//------------------------------------------------------------------------
// _exit
//------------------------------------------------------------------------
// Exit a program without cleaning up files.
void _exit(int exit_status)
{
asm volatile ("sbreak");
__builtin_unreachable();
}

472
scripts/cxxdemo/syscalls.c
View File

@ -1,447 +1,80 @@
// An extremely minimalist syscalls.c for newlib
// Based on riscv newlib libgloss/riscv/machine/syscall.h
// Changes by Clifford Wolf
//========================================================================
// syscalls.c : Newlib operating system interface
//========================================================================
// This is the maven implementation of the narrow newlib operating
// system interface. It is based on the minimum stubs in the newlib
// documentation, the error stubs in libnosys, and the previous scale
// implementation. Please do not include any additional system calls or
// other functions in this file. Additional header and source files
// should be in the machine subdirectory.
//
// Here is a list of the functions which make up the operating system
// interface. The file management instructions execute syscall assembly
// instructions so that a proxy kernel (or the simulator) can marshal up
// the request to the host machine. The process management functions are
// mainly just stubs since for now maven only supports a single process.
//
// - File management functions
// + open : (v) open file
// + lseek : (v) set position in file
// + read : (v) read from file
// + write : (v) write to file
// + fstat : (z) status of an open file
// + stat : (z) status of a file by name
// + close : (z) close a file
// + link : (z) rename a file
// + unlink : (z) remote file's directory entry
//
// - Process management functions
// + execve : (z) transfer control to new proc
// + fork : (z) create a new process
// + getpid : (v) get process id
// + kill : (z) send signal to child process
// + wait : (z) wait for a child process
//
// - Misc functions
// + isatty : (v) query whether output stream is a terminal
// + times : (z) timing information for current process
// + sbrk : (v) increase program data space
// + _exit : (-) exit program without cleaning up files
//
// There are two types of system calls. Those which return a value when
// everything is okay (marked with (v) in above list) and those which
// return a zero when everything is okay (marked with (z) in above
// list). On an error (ie. when the error flag is 1) the return value is
// always an errno which should correspond to the numbers in
// newlib/libc/include/sys/errno.h
//
// Note that really I think we are supposed to define versions of these
// functions with an underscore prefix (eg. _open). This is what some of
// the newlib documentation says, and all the newlib code calls the
// underscore version. This is because technically I don't think we are
// supposed to pollute the namespace with these function names. If you
// define MISSING_SYSCALL_NAMES in xcc/src/newlib/configure.host
// then xcc/src/newlib/libc/include/_syslist.h will essentially define
// all of the underscore versions to be equal to the non-underscore
// versions. I tried not defining MISSING_SYSCALL_NAMES, and newlib
// compiled fine but libstdc++ complained about not being able to fine
// write, read, etc. So for now we do not use underscores (and we do
// define MISSING_SYSCALL_NAMES).
//
// See the newlib documentation for more information
// http://sourceware.org/newlib/libc.html#Syscalls
// Written by Clifford Wolf.
#include <sys/stat.h>
#include <sys/times.h>
#include <sys/time.h>
#include <sys/timeb.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <utime.h>
#include <errno.h>
//------------------------------------------------------------------------
// environment
//------------------------------------------------------------------------
// A pointer to a list of environment variables and their values. For a
// minimal environment, this empty list is adequate. We used to define
// environ here but it is already defined in
// xcc/src/newlib/libc/stdlib/environ.c so to avoid multiple definition
// errors we have commented this out for now.
//
// char* __env[1] = { 0 };
// char** environ = __env;
//------------------------------------------------------------------------
// open
//------------------------------------------------------------------------
// Open a file.
#define UNIMPL_FUNC(_f) ".globl " #_f "\n.type " #_f ", @function\n" #_f ":\n"
int open(const char* name, int flags, int mode)
asm (
".text\n"
".align 2\n"
UNIMPL_FUNC(open)
UNIMPL_FUNC(openat)
UNIMPL_FUNC(lseek)
UNIMPL_FUNC(stat)
UNIMPL_FUNC(lstat)
UNIMPL_FUNC(fstatat)
UNIMPL_FUNC(isatty)
UNIMPL_FUNC(access)
UNIMPL_FUNC(faccessat)
UNIMPL_FUNC(link)
UNIMPL_FUNC(unlink)
UNIMPL_FUNC(execve)
UNIMPL_FUNC(getpid)
UNIMPL_FUNC(fork)
UNIMPL_FUNC(kill)
UNIMPL_FUNC(wait)
UNIMPL_FUNC(times)
UNIMPL_FUNC(gettimeofday)
UNIMPL_FUNC(ftime)
UNIMPL_FUNC(utime)
UNIMPL_FUNC(chown)
UNIMPL_FUNC(chmod)
UNIMPL_FUNC(chdir)
UNIMPL_FUNC(getcwd)
UNIMPL_FUNC(sysconf)
"j unimplemented_syscall\n"
);
void unimplemented_syscall()
{
errno = ENOENT;
return -1;
const char *p = "Unimplemented system call called!\n";
while (*p)
*(volatile int*)0x10000000 = *(p++);
asm volatile ("sbreak");
__builtin_unreachable();
}
//------------------------------------------------------------------------
// openat
//------------------------------------------------------------------------
// Open file relative to given directory
int openat(int dirfd, const char* name, int flags, int mode)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// lseek
//------------------------------------------------------------------------
// Set position in a file.
off_t lseek(int file, off_t ptr, int dir)
{
errno = ESPIPE;
return -1;
}
//----------------------------------------------------------------------
// read
//----------------------------------------------------------------------
// Read from a file.
ssize_t read(int file, void *ptr, size_t len)
{
// always EOF
return 0;
}
//------------------------------------------------------------------------
// write
//------------------------------------------------------------------------
// Write to a file.
ssize_t write(int file, const void *ptr, size_t len)
{
unsigned int *p = (unsigned int*)0x10000000;
const void *eptr = ptr + len;
while (ptr != eptr)
*p = *(char*)(ptr++);
*(volatile int*)0x10000000 = *(char*)(ptr++);
return len;
}
//------------------------------------------------------------------------
// fstat
//------------------------------------------------------------------------
// Status of an open file. The sys/stat.h header file required is
// distributed in the include subdirectory for this C library.
int close(int file)
{
// close is called before _exit()
return 0;
}
int fstat(int file, struct stat *st)
{
// fstat is called during libc startup
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// stat
//------------------------------------------------------------------------
// Status of a file (by name).
int stat(const char *file, struct stat *st)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// lstat
//------------------------------------------------------------------------
// Status of a link (by name).
int lstat(const char *file, struct stat *st)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// fstatat
//------------------------------------------------------------------------
// Status of a file (by name) in a given directory.
int fstatat(int dirfd, const char *file, struct stat *st, int flags)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// access
//------------------------------------------------------------------------
// Permissions of a file (by name).
int access(const char *file, int mode)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// faccessat
//------------------------------------------------------------------------
// Permissions of a file (by name) in a given directory.
int faccessat(int dirfd, const char *file, int mode, int flags)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// close
//------------------------------------------------------------------------
// Close a file.
int close(int file)
{
// close is always ok
return 0;
}
//------------------------------------------------------------------------
// link
//------------------------------------------------------------------------
// Establish a new name for an existing file.
int link(const char *old_name, const char *new_name)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// unlink
//------------------------------------------------------------------------
// Remove a file's directory entry.
int unlink(const char *name)
{
errno = ENOENT;
return -1;
}
//------------------------------------------------------------------------
// execve
//------------------------------------------------------------------------
// Transfer control to a new process. Minimal implementation for a
// system without processes from newlib documentation.
int execve(const char *name, char *const argv[], char *const env[])
{
errno = ENOMEM;
return -1;
}
//------------------------------------------------------------------------
// fork
//------------------------------------------------------------------------
// Create a new process. Minimal implementation for a system without
// processes from newlib documentation.
int fork()
{
errno = EAGAIN;
return -1;
}
//------------------------------------------------------------------------
// getpid
//------------------------------------------------------------------------
// Get process id. This is sometimes used to generate strings unlikely
// to conflict with other processes. Minimal implementation for a
// system without processes just returns 1.
int getpid()
{
return 1;
}
//------------------------------------------------------------------------
// kill
//------------------------------------------------------------------------
// Send a signal. Minimal implementation for a system without processes
// just causes an error.
int kill(int pid, int sig)
{
errno = EINVAL;
return -1;
}
//------------------------------------------------------------------------
// wait
//------------------------------------------------------------------------
// Wait for a child process. Minimal implementation for a system without
// processes just causes an error.
int wait(int *status)
{
errno = ECHILD;
return -1;
}
//------------------------------------------------------------------------
// isatty
//------------------------------------------------------------------------
// Query whether output stream is a terminal. For consistency with the
// other minimal implementations, which only support output to stdout,
// this minimal implementation is suggested by the newlib docs.
int isatty(int file)
{
return 1;
}
//------------------------------------------------------------------------
// times
//------------------------------------------------------------------------
// Timing information for current process. From
// newlib/libc/include/sys/times.h the tms struct fields are as follows:
//
// - clock_t tms_utime : user clock ticks
// - clock_t tms_stime : system clock ticks
// - clock_t tms_cutime : children's user clock ticks
// - clock_t tms_cstime : children's system clock ticks
//
// Since maven does not currently support processes we set both of the
// children's times to zero. Eventually we might want to separately
// account for user vs system time, but for now we just return the total
// number of cycles since starting the program.
clock_t times(struct tms *buf)
{
// when called for the first time, initialize t0
static struct timeval t0;
if (t0.tv_sec == 0)
gettimeofday(&t0, 0);
struct timeval t;
gettimeofday(&t, 0);
long long utime = (t.tv_sec - t0.tv_sec) * 1000000 + (t.tv_usec - t0.tv_usec);
buf->tms_utime = utime * CLOCKS_PER_SEC / 1000000;
buf->tms_stime = buf->tms_cstime = buf->tms_cutime = 0;
return -1;
}
//----------------------------------------------------------------------
// gettimeofday
//----------------------------------------------------------------------
// Get the current time. Only relatively correct.
int gettimeofday(struct timeval *tp, void *tzp)
{
asm volatile ("sbreak");
__builtin_unreachable();
}
//----------------------------------------------------------------------
// ftime
//----------------------------------------------------------------------
// Get the current time. Only relatively correct.
int ftime(struct timeb *tp)
{
tp->time = tp->millitm = 0;
return 0;
}
//----------------------------------------------------------------------
// utime
//----------------------------------------------------------------------
// Stub.
int utime(const char *path, const struct utimbuf *times)
{
return -1;
}
//----------------------------------------------------------------------
// chown
//----------------------------------------------------------------------
// Stub.
int chown(const char *path, uid_t owner, gid_t group)
{
return -1;
}
//----------------------------------------------------------------------
// chmod
//----------------------------------------------------------------------
// Stub.
int chmod(const char *path, mode_t mode)
{
return -1;
}
//----------------------------------------------------------------------
// chdir
//----------------------------------------------------------------------
// Stub.
int chdir(const char *path)
{
return -1;
}
//----------------------------------------------------------------------
// getcwd
//----------------------------------------------------------------------
// Stub.
char *getcwd(char *buf, size_t size)
{
return NULL;
}
//----------------------------------------------------------------------
// sysconf
//----------------------------------------------------------------------
// Get configurable system variables
long sysconf(int name)
{
switch (name) {
case _SC_CLK_TCK:
return CLOCKS_PER_SEC;
}
return -1;
}
//----------------------------------------------------------------------
// sbrk
//----------------------------------------------------------------------
// Increase program data space. As malloc and related functions depend
// on this, it is useful to have a working implementation. The following
// is suggested by the newlib docs and suffices for a standalone
// system.
void *sbrk(ptrdiff_t incr)
{
extern unsigned char _end[]; // Defined by linker
@ -450,20 +83,13 @@ void *sbrk(ptrdiff_t incr)
if (heap_end == 0)
heap_end = (long)_end;
// if (syscall_errno(SYS_brk, heap_end + incr, 0, 0, 0) != heap_end + incr)
// return (void *)-1;
heap_end += incr;
return (void *)(heap_end - incr);
}
//------------------------------------------------------------------------
// _exit
//------------------------------------------------------------------------
// Exit a program without cleaning up files.
void _exit(int exit_status)
{
asm volatile ("sbreak");
__builtin_unreachable();
}