linux/arch/um/kernel/time.c
Bodo Stroesser 9786a8f3cb [PATCH] uml: Proper clone support for skas0
This patch implements the clone-stub mechanism, which allows skas0 to run
with proc_mm==0, even if the clib in UML uses modify_ldt.

Note: There is a bug in skas3.v7 host patch, that avoids UML-skas from
running properly on a SMP-box.  In full skas3, I never really saw problems,
but in skas0 they showed up.

More commentary by jdike - What this patch does is makes sure that the host
parent of each new host process matches the UML parent of the corresponding
UML process.  This ensures that any changed LDTs are inherited.  This is
done by having clone actually called by the UML process from its stub,
rather than by the kernel.  We have special syscall stubs that are loaded
onto the stub code page because that code must be completely
self-contained.  These stubs are given C interfaces, and used like normal C
functions, but there are subtleties.  Principally, we have to be careful
about stack variables in stub_clone_handler after the clone.  The code is
written so that there aren't any - everything boils down to a fixed
address.  If there were any locals, references to them after the clone
would be wrong because the stack just changed.

Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-07 18:23:44 -07:00

172 lines
3.8 KiB
C

/*
* Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
* Licensed under the GPL
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <sys/time.h>
#include <signal.h>
#include <errno.h>
#include "user_util.h"
#include "kern_util.h"
#include "user.h"
#include "process.h"
#include "signal_user.h"
#include "time_user.h"
#include "kern_constants.h"
/* XXX This really needs to be declared and initialized in a kernel file since
* it's in <linux/time.h>
*/
extern struct timespec wall_to_monotonic;
extern struct timeval xtime;
struct timeval local_offset = { 0, 0 };
void timer(void)
{
gettimeofday(&xtime, NULL);
timeradd(&xtime, &local_offset, &xtime);
}
static void set_interval(int timer_type)
{
int usec = 1000000/hz();
struct itimerval interval = ((struct itimerval) { { 0, usec },
{ 0, usec } });
if(setitimer(timer_type, &interval, NULL) == -1)
panic("setitimer failed - errno = %d\n", errno);
}
void enable_timer(void)
{
set_interval(ITIMER_VIRTUAL);
}
void prepare_timer(void * ptr)
{
int usec = 1000000/hz();
*(struct itimerval *)ptr = ((struct itimerval) { { 0, usec },
{ 0, usec }});
}
void disable_timer(void)
{
struct itimerval disable = ((struct itimerval) { { 0, 0 }, { 0, 0 }});
if((setitimer(ITIMER_VIRTUAL, &disable, NULL) < 0) ||
(setitimer(ITIMER_REAL, &disable, NULL) < 0))
printk("disnable_timer - setitimer failed, errno = %d\n",
errno);
/* If there are signals already queued, after unblocking ignore them */
set_handler(SIGALRM, SIG_IGN, 0, -1);
set_handler(SIGVTALRM, SIG_IGN, 0, -1);
}
void switch_timers(int to_real)
{
struct itimerval disable = ((struct itimerval) { { 0, 0 }, { 0, 0 }});
struct itimerval enable = ((struct itimerval) { { 0, 1000000/hz() },
{ 0, 1000000/hz() }});
int old, new;
if(to_real){
old = ITIMER_VIRTUAL;
new = ITIMER_REAL;
}
else {
old = ITIMER_REAL;
new = ITIMER_VIRTUAL;
}
if((setitimer(old, &disable, NULL) < 0) ||
(setitimer(new, &enable, NULL)))
printk("switch_timers - setitimer failed, errno = %d\n",
errno);
}
void uml_idle_timer(void)
{
if(signal(SIGVTALRM, SIG_IGN) == SIG_ERR)
panic("Couldn't unset SIGVTALRM handler");
set_handler(SIGALRM, (__sighandler_t) alarm_handler,
SA_RESTART, SIGUSR1, SIGIO, SIGWINCH, SIGVTALRM, -1);
set_interval(ITIMER_REAL);
}
extern int do_posix_clock_monotonic_gettime(struct timespec *tp);
void time_init(void)
{
struct timespec now;
if(signal(SIGVTALRM, boot_timer_handler) == SIG_ERR)
panic("Couldn't set SIGVTALRM handler");
set_interval(ITIMER_VIRTUAL);
do_posix_clock_monotonic_gettime(&now);
wall_to_monotonic.tv_sec = -now.tv_sec;
wall_to_monotonic.tv_nsec = -now.tv_nsec;
}
/* Declared in linux/time.h, which can't be included here */
extern void clock_was_set(void);
void do_gettimeofday(struct timeval *tv)
{
unsigned long flags;
flags = time_lock();
gettimeofday(tv, NULL);
timeradd(tv, &local_offset, tv);
time_unlock(flags);
clock_was_set();
}
int do_settimeofday(struct timespec *tv)
{
struct timeval now;
unsigned long flags;
struct timeval tv_in;
if ((unsigned long) tv->tv_nsec >= UM_NSEC_PER_SEC)
return -EINVAL;
tv_in.tv_sec = tv->tv_sec;
tv_in.tv_usec = tv->tv_nsec / 1000;
flags = time_lock();
gettimeofday(&now, NULL);
timersub(&tv_in, &now, &local_offset);
time_unlock(flags);
return(0);
}
void idle_sleep(int secs)
{
struct timespec ts;
ts.tv_sec = secs;
ts.tv_nsec = 0;
nanosleep(&ts, NULL);
}
/* XXX This partly duplicates init_irq_signals */
void user_time_init(void)
{
set_handler(SIGVTALRM, (__sighandler_t) alarm_handler,
SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGWINCH,
SIGALRM, SIGUSR2, -1);
set_handler(SIGALRM, (__sighandler_t) alarm_handler,
SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGWINCH,
SIGVTALRM, SIGUSR2, -1);
set_interval(ITIMER_VIRTUAL);
}