From 44f5c4ced6ddee2f5f2e45fa45b93370245d85bd Mon Sep 17 00:00:00 2001
From: Jeff Dike <jdike@addtoit.com>
Date: Wed, 7 Mar 2007 20:41:26 -0800
Subject: [PATCH] [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>
---
arch/um/sys-x86_64/syscalls.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/um/sys-x86_64/syscalls.c b/arch/um/sys-x86_64/syscalls.c
index 01b91f9fa789..b3f6350cac44 100644
--- a/arch/um/sys-x86_64/syscalls.c
+++ b/arch/um/sys-x86_64/syscalls.c
@@ -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, ¤t->thread.regs.regs);
+ break;
case ARCH_SET_GS:
save_registers(pid, ¤t->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);
}
-