From: Dave Hansen <dave.han...@linux.intel.com>

The uprobes code has a nice helper, is_64bit_mm(), that consults both
the runtime and compile-time flags for 32-bit support.  Instead of
reinventing the wheel, pull it in to an x86 header so we can use it
for MPX.

I prefer passing the mm around to test_thread_flag(TIF_IA32) because
it makes it explicit where the context is coming from.

Signed-off-by: Dave Hansen <dave.han...@linux.intel.com>
Cc: Oleg Nesterov <o...@redhat.com>
Reviewed-by: Thomas Gleixner <t...@linutronix.de>
---

 b/arch/x86/include/asm/mmu_context.h |   13 +++++++++++++
 b/arch/x86/kernel/uprobes.c          |   10 +---------
 2 files changed, 14 insertions(+), 9 deletions(-)

diff -puN arch/x86/include/asm/mmu_context.h~x86-make-is_64bit_mm-available 
arch/x86/include/asm/mmu_context.h
--- a/arch/x86/include/asm/mmu_context.h~x86-make-is_64bit_mm-available 
2015-05-27 09:32:19.172654492 -0700
+++ b/arch/x86/include/asm/mmu_context.h        2015-05-27 09:32:19.177654718 
-0700
@@ -142,6 +142,19 @@ static inline void arch_exit_mmap(struct
        paravirt_arch_exit_mmap(mm);
 }
 
+#ifdef CONFIG_X86_64
+static inline bool is_64bit_mm(struct mm_struct *mm)
+{
+       return  !config_enabled(CONFIG_IA32_EMULATION) ||
+               !(mm->context.ia32_compat == TIF_IA32);
+}
+#else
+static inline bool is_64bit_mm(struct mm_struct *mm)
+{
+       return false;
+}
+#endif
+
 static inline void arch_bprm_mm_init(struct mm_struct *mm,
                struct vm_area_struct *vma)
 {
diff -puN arch/x86/kernel/uprobes.c~x86-make-is_64bit_mm-available 
arch/x86/kernel/uprobes.c
--- a/arch/x86/kernel/uprobes.c~x86-make-is_64bit_mm-available  2015-05-27 
09:32:19.173654537 -0700
+++ b/arch/x86/kernel/uprobes.c 2015-05-27 09:32:19.177654718 -0700
@@ -29,6 +29,7 @@
 #include <linux/kdebug.h>
 #include <asm/processor.h>
 #include <asm/insn.h>
+#include <asm/mmu_context.h>
 
 /* Post-execution fixups. */
 
@@ -312,11 +313,6 @@ static int uprobe_init_insn(struct arch_
 }
 
 #ifdef CONFIG_X86_64
-static inline bool is_64bit_mm(struct mm_struct *mm)
-{
-       return  !config_enabled(CONFIG_IA32_EMULATION) ||
-               !(mm->context.ia32_compat == TIF_IA32);
-}
 /*
  * If arch_uprobe->insn doesn't use rip-relative addressing, return
  * immediately.  Otherwise, rewrite the instruction so that it accesses
@@ -497,10 +493,6 @@ static void riprel_post_xol(struct arch_
        }
 }
 #else /* 32-bit: */
-static inline bool is_64bit_mm(struct mm_struct *mm)
-{
-       return false;
-}
 /*
  * No RIP-relative addressing on 32-bit
  */
_
--
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