From: Dave Hansen <[email protected]>
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 <[email protected]> Cc: [email protected] Cc: Andy Lutomirski <[email protected]> --- b/include/uapi/linux/prctl.h | 2 +- b/kernel/sys.c | 16 ++-------------- 2 files changed, 3 insertions(+), 15 deletions(-) diff -puN include/uapi/linux/prctl.h~mpx-remove-apis include/uapi/linux/prctl.h --- a/include/uapi/linux/prctl.h~mpx-remove-apis 2019-07-05 10:40:49.441907046 -0700 +++ b/include/uapi/linux/prctl.h 2019-07-05 10:40:49.447907046 -0700 @@ -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 -puN kernel/sys.c~mpx-remove-apis kernel/sys.c --- a/kernel/sys.c~mpx-remove-apis 2019-07-05 10:40:49.444907046 -0700 +++ b/kernel/sys.c 2019-07-05 10:40:49.448907046 -0700 @@ -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, unsi 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; _
