fix for user-level i/o-base corruption
I found that the I/O base in ar.k0 was wrong on my systems. This turns out to be due to a bug in the ia32 subsystem: it fails to reset the original i/o-base address when execve'ing an IA-64 program. The patch below fixes this.
I wonder whether this bug may be the root of the crashes that occasionally occur when switching from XFree86 to a virtual consoles.
--david
arch/ia64/ia32/sys_ia32.c +4 -3
@@ -124,14 +124,16 @@ old_map_base = current->thread.map_base; old_task_size = current->thread.task_size; -/* we may be exec'ing a 64-bit process: reset map base & task-size: */ +/* we may be exec'ing a 64-bit process: reset map base, task-size, and io-base: */ current->thread.map_base =DEFAULT_MAP_BASE ; current->thread.task_size =DEFAULT_TASK_SIZE ; +ia64_set_kr (IA64_KR_IO_BASE , current->thread.old_iob);set_fs (KERNEL_DS ); r =sys_execve (filename, av, ae, regs);if (r <0 ) { -/* oops, execve failed, switch back to old map base & task-size: */ +/* oops, execve failed, switch back to old values... */ +ia64_set_kr (IA64_KR_IO_BASE ,IA32_IOBASE ); current->thread.map_base = old_map_base; current->thread.task_size = old_task_size;set_fs (USER_DS );/* establish new task-size as the address-limit */
@@ -2612,7 +2614,6 @@up_write (¤t->mm->mmap_sem);if (addr >=0 ) { -ia64_set_kr (IA64_KR_IO_BASE , addr); old = (old & ~0x3000 ) | (level <<12 ); __asm__ __volatile__("mov ar.eflag=%0 ;;" ::"r" (old)); }