unsigned long flags;
int err, vtalrm, alrm, prof, cpu;
char c;
- /* jailing and SMP are incompatible, so this doesn't need to be
- * made per-cpu
- */
- static int reading;
from = prev;
to = next;
c = 0;
set_current(to);
- reading = 0;
err = os_write_file(to->thread.mode.tt.switch_pipe[1], &c, sizeof(c));
if(err != sizeof(c))
panic("write of switch_pipe failed, err = %d", -err);
- reading = 1;
- if((from->exit_state == EXIT_ZOMBIE) ||
- (from->exit_state == EXIT_DEAD))
+ if(from->thread.mode.tt.switch_pipe[0] == -1)
os_kill_process(os_getpid(), 0);
err = os_read_file(from->thread.mode.tt.switch_pipe[0], &c, sizeof(c));
* in case it has not already killed itself.
*/
prev_sched = current->thread.prev_sched;
- if((prev_sched->exit_state == EXIT_ZOMBIE) ||
- (prev_sched->exit_state == EXIT_DEAD))
+ if(prev_sched->thread.mode.tt.switch_pipe[0] == -1)
os_kill_process(prev_sched->thread.mode.tt.extern_pid, 1);
- /* This works around a nasty race with 'jail'. If we are switching
- * between two threads of a threaded app and the incoming process
- * runs before the outgoing process reaches the read, and it makes
- * it all the way out to userspace, then it will have write-protected
- * the outgoing process stack. Then, when the outgoing process
- * returns from the write, it will segfault because it can no longer
- * write its own stack. So, in order to avoid that, the incoming
- * thread sits in a loop yielding until 'reading' is set. This
- * isn't entirely safe, since there may be a reschedule from a timer
- * happening between setting 'reading' and sleeping in read. But,
- * it should get a whole quantum in which to reach the read and sleep,
- * which should be enough.
- */
-
- if(jail){
- while(!reading) sched_yield();
- }
-
change_sig(SIGVTALRM, vtalrm);
change_sig(SIGALRM, alrm);
change_sig(SIGPROF, prof);
{
int pid = task->thread.mode.tt.extern_pid;
+ /*
+ * We first have to kill the other process, before
+ * closing its switch_pipe. Else it might wake up
+ * and receive "EOF" before we could kill it.
+ */
if(os_getpid() != pid)
os_kill_process(pid, 0);
-}
-void exit_thread_tt(void)
-{
- os_close_file(current->thread.mode.tt.switch_pipe[0]);
- os_close_file(current->thread.mode.tt.switch_pipe[1]);
+ os_close_file(task->thread.mode.tt.switch_pipe[0]);
+ os_close_file(task->thread.mode.tt.switch_pipe[1]);
+ /* use switch_pipe as flag: thread is released */
+ task->thread.mode.tt.switch_pipe[0] = -1;
}
void suspend_new_thread(int fd)
default_idle();
}
-/* Changed by jail_setup, which is a setup */
-int jail = 0;
-
-int __init jail_setup(char *line, int *add)
-{
- int ok = 1;
-
- if(jail) return(0);
-#ifdef CONFIG_SMP
- printf("'jail' may not used used in a kernel with CONFIG_SMP "
- "enabled\n");
- ok = 0;
-#endif
-#ifdef CONFIG_HOSTFS
- printf("'jail' may not used used in a kernel with CONFIG_HOSTFS "
- "enabled\n");
- ok = 0;
-#endif
-#ifdef CONFIG_MODULES
- printf("'jail' may not used used in a kernel with CONFIG_MODULES "
- "enabled\n");
- ok = 0;
-#endif
- if(!ok) exit(1);
-
- /* CAP_SYS_RAWIO controls the ability to open /dev/mem and /dev/kmem.
- * Removing it from the bounding set eliminates the ability of anything
- * to acquire it, and thus read or write kernel memory.
- */
- cap_lower(cap_bset, CAP_SYS_RAWIO);
- jail = 1;
- return(0);
-}
-
-__uml_setup("jail", jail_setup,
-"jail\n"
-" Enables the protection of kernel memory from processes.\n\n"
-);
-
-static void mprotect_kernel_mem(int w)
-{
- unsigned long start, end;
- int pages;
-
- if(!jail || (current == &init_task)) return;
-
- pages = (1 << CONFIG_KERNEL_STACK_ORDER);
-
- start = (unsigned long) current_thread + PAGE_SIZE;
- end = (unsigned long) current_thread + PAGE_SIZE * pages;
- protect_memory(uml_reserved, start - uml_reserved, 1, w, 1, 1);
- protect_memory(end, high_physmem - end, 1, w, 1, 1);
-
- start = (unsigned long) UML_ROUND_DOWN(&_stext);
- end = (unsigned long) UML_ROUND_UP(&_etext);
- protect_memory(start, end - start, 1, w, 1, 1);
-
- start = (unsigned long) UML_ROUND_DOWN(&_unprotected_end);
- end = (unsigned long) UML_ROUND_UP(&_edata);
- protect_memory(start, end - start, 1, w, 1, 1);
-
- start = (unsigned long) UML_ROUND_DOWN(&__bss_start);
- end = (unsigned long) UML_ROUND_UP(brk_start);
- protect_memory(start, end - start, 1, w, 1, 1);
-
- mprotect_kernel_vm(w);
-}
-
-void unprotect_kernel_mem(void)
-{
- mprotect_kernel_mem(1);
-}
-
-void protect_kernel_mem(void)
-{
- mprotect_kernel_mem(0);
-}
-
extern void start_kernel(void);
static int start_kernel_proc(void *unused)
git://git.onelab.eu / linux-2.6.git / blobdiff