[PATCH] uml: arch_prctl should set thread fs

44f5c4ce · Jeff Dike <[email protected]> · 2007-03-07 20:41:26 -08:00

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 <[email protected]>
Cc: Paolo 'Blaisorblade' Giarrusso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: 44f5c4ced6ddee2f5f2e45fa45b93370245d85bd
Parents: 9bebff6c

Changes

1 files changed · +4 −2

File	Status	Add	Del	Content
arch/um/sys-x86_64/syscalls.c	modified	+4	−2	View file

arch/um/sys-x86_64/syscalls.c

View file

diff --git a/arch/um/sys-x86_64/syscalls.c b/arch/um/sys-x86_64/syscalls.c
index 01b91f9..b3f6350 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, &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);
 }
-