From: Dave Hansen <dave.hansen@linux.intel.com>
Date: Sun, 7 Jun 2015 18:37:06 +0000 (-0700)
Subject: x86/mpx: Allow 32-bit binaries on 64-bit kernels again
X-Git-Tag: firefly_0821_release~176^2~1627^2~1
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=97ac46a5087eaf87fd76ff7bb31ec9c896010442;p=firefly-linux-kernel-4.4.55.git

x86/mpx: Allow 32-bit binaries on 64-bit kernels again

Now that the bugs in mixed mode MPX handling are fixed, re-allow
32-bit binaries on 64-bit kernels again.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183706.70277DAD@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 6233d5195f01..7a657f58bbea 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -366,12 +366,6 @@ static __user void *mpx_get_bounds_dir(void)
 	if (!cpu_feature_enabled(X86_FEATURE_MPX))
 		return MPX_INVALID_BOUNDS_DIR;
 
-	/*
-	 * 32-bit binaries on 64-bit kernels are currently
-	 * unsupported.
-	 */
-	if (IS_ENABLED(CONFIG_X86_64) && test_thread_flag(TIF_IA32))
-		return MPX_INVALID_BOUNDS_DIR;
 	/*
 	 * The bounds directory pointer is stored in a register
 	 * only accessible if we first do an xsave.