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[PATCH] uml: arch_prctl should set thread fs 

In my previous x86_64 thread fix, I forgot to initialize thread.arch.fs in
arch_prctl.  A process calling arch_prctl to set %fs would lose it on the
next context switch.

It also turns out that you can switch to a process which is in the process
of exiting and which has lost its mm.  In this case, it's worse than
useless to try to call arch_prctl on the host process.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Jeff Dike 2007-03-07 20:41:26 -08:00 committed by Linus Torvalds
parent 9bebff6ca5
commit 44f5c4ced6
1 changed files with 4 additions and 2 deletions
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6
arch/um/sys-x86_64/syscalls.c
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@ -103,6 +103,9 @@ long arch_prctl_skas(struct task_struct *task, int code,
switch(code){
case ARCH_SET_FS:
current->thread.arch.fs = (unsigned long) ptr;
save_registers(pid, &current->thread.regs.regs);
break;
case ARCH_SET_GS:
save_registers(pid, &current->thread.regs.regs);
break;
@ -140,9 +143,8 @@ long sys_clone(unsigned long clone_flags, unsigned long newsp,
void arch_switch_to_skas(struct task_struct *from, struct task_struct *to)
{
if(to->thread.arch.fs == 0)
if((to->thread.arch.fs == 0) || (to->mm == NULL))
return;
arch_prctl_skas(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
}