x86: mark associated mm when running a task in 32 bit compatibility mode

This patch simply follows the same practice as for setting the TIF_IA32 flag.
In particular, an mm is marked as holding 32-bit tasks when a 32-bit binary is
exec'ed.  Both ELF and a.out formats are updated.

Signed-off-by: Stephen Wilson <wilsons@start.ca>
Reviewed-by: Michel Lespinasse <walken@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index bd387e8f73b4..6c9dd922ac0d 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -501,6 +501,10 @@ void set_personality_64bit(void)
         /* Make sure to be in 64bit mode */
         clear_thread_flag(TIF_IA32);
 
+        /* Ensure the corresponding mm is not marked. */
+        if (current->mm)
+                current->mm->context.ia32_compat = 0;
+
         /* TBD: overwrites user setup. Should have two bits.
            But 64bit processes have always behaved this way,
            so it's not too bad. The main problem is just that
@@ -516,6 +520,10 @@ void set_personality_ia32(void)
         set_thread_flag(TIF_IA32);
         current->personality |= force_personality32;
 
+        /* Mark the associated mm as containing 32-bit tasks. */
+        if (current->mm)
+                current->mm->context.ia32_compat = 1;
+
         /* Prepare the first "return" to user space */
         current_thread_info()->status |= TS_COMPAT;
 }