uprobes/x86: Fix is_64bit_mm() with CONFIG_X86_X32

is_64bit_mm() assumes that mm->context.ia32_compat means the 32-bit
instruction set, this is not true if the task is TIF_X32.

Change set_personality_ia32() to initialize mm->context.ia32_compat
by TIF_X32 or TIF_IA32 instead of 1. This allows to fix is_64bit_mm()
without affecting other users, they all treat ia32_compat as "bool".

TIF_ in ->ia32_compat looks a bit strange, but this is grep-friendly
and avoids the new define's.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

2 files changed, 5 insertions, 4 deletions

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 9c0280f93d05..9b53940981b7 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -413,12 +413,11 @@ void set_personality_ia32(bool x32)
         set_thread_flag(TIF_ADDR32);
 
         /* Mark the associated mm as containing 32-bit tasks. */
-        if (current->mm)
-                current->mm->context.ia32_compat = 1;
-
         if (x32) {
                 clear_thread_flag(TIF_IA32);
                 set_thread_flag(TIF_X32);
+                if (current->mm)
+                        current->mm->context.ia32_compat = TIF_X32;
                 current->personality &= ~READ_IMPLIES_EXEC;
                 /* is_compat_task() uses the presence of the x32
                    syscall bit flag to determine compat status */
@@ -426,6 +425,8 @@ void set_personality_ia32(bool x32)
         } else {
                 set_thread_flag(TIF_IA32);
                 clear_thread_flag(TIF_X32);
+                if (current->mm)
+                        current->mm->context.ia32_compat = TIF_IA32;
                 current->personality |= force_personality32;
                 /* Prepare the first "return" to user space */
                 current_thread_info()->status |= TS_COMPAT;
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 892975b3c99c..ecbffd16d090 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -245,7 +245,7 @@ static int uprobe_init_insn(struct arch_uprobe *auprobe, struct insn *insn, bool
 static inline bool is_64bit_mm(struct mm_struct *mm)
 {
         return  !config_enabled(CONFIG_IA32_EMULATION) ||
-                !mm->context.ia32_compat;
+                !(mm->context.ia32_compat == TIF_IA32);
 }
 /*
  * If arch_uprobe->insn doesn't use rip-relative addressing, return