x86/mpx: remove MPX APIs
From: Dave Hansen <dave.hansen@linux.intel.com>
MPX is being removed from the kernel due to a lack of support
in the toolchain going forward (gcc).
The first thing we need to do is remove the userspace-visible
ABIs so that applications will stop using it. The most visible
one are the enable/disable prctl()s. Remove them first.
This is the most minimal and least invasive patch needed to
ensure that apps stop using MPX with new kernels.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: Andy Lutomirski <luto@kernel.org>
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index 094bb03..961e0a4 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -181,7 +181,7 @@ struct prctl_mm_map {
#define PR_GET_THP_DISABLE 42
/*
- * Tell the kernel to start/stop helping userspace manage bounds tables.
+ * No longer implemented, but left here to ensure the numbers stay reserved:
*/
#define PR_MPX_ENABLE_MANAGEMENT 43
#define PR_MPX_DISABLE_MANAGEMENT 44
diff --git a/kernel/sys.c b/kernel/sys.c
index 2969304..384b000b 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -103,12 +103,6 @@
#ifndef SET_TSC_CTL
# define SET_TSC_CTL(a) (-EINVAL)
#endif
-#ifndef MPX_ENABLE_MANAGEMENT
-# define MPX_ENABLE_MANAGEMENT() (-EINVAL)
-#endif
-#ifndef MPX_DISABLE_MANAGEMENT
-# define MPX_DISABLE_MANAGEMENT() (-EINVAL)
-#endif
#ifndef GET_FP_MODE
# define GET_FP_MODE(a) (-EINVAL)
#endif
@@ -2456,15 +2450,9 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
up_write(&me->mm->mmap_sem);
break;
case PR_MPX_ENABLE_MANAGEMENT:
- if (arg2 || arg3 || arg4 || arg5)
- return -EINVAL;
- error = MPX_ENABLE_MANAGEMENT();
- break;
case PR_MPX_DISABLE_MANAGEMENT:
- if (arg2 || arg3 || arg4 || arg5)
- return -EINVAL;
- error = MPX_DISABLE_MANAGEMENT();
- break;
+ /* No longer implemented: */
+ return -EINVAL;
case PR_SET_FP_MODE:
error = SET_FP_MODE(me, arg2);
break;
